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Tektronix 7904A User's Manual

1. NO OUTPUT PULSE LO OUTPUT Positive going pulse Where both A and B Hoidoff are required to be a at either input produces an alternate pulse Negative going pulse 3 or Chop Mode When the HORIZONTAL MODE switch is set to ALT or CHOP the A time base unit must be in independent nondelayed mode an Alternate Pulse is produced at the end of each sweep For example an Alternate Pulse is produced at the end of the A sweep then at the end of the B sweep again at the end of the A sweep etc Although Alternate Pulses are also produced in the CHOP horizontal mode they are not used in this instrument 4 Delayed Sweep A Delays When the A time base unit is set for delayed operation the Alternate Pulse Generator produces an Alternate Pulse only at the end of the A Sweep even when the HORIZONTAL MODE switch is set to B This is necessary since the A time base sets the delay time for the time base unit whenever B is displayed 5 Amplifier Unit In Horizontal Compartment When an amplifier unit is installed in either of the horizontal plug in compartments the Alternate Pulse can be produced from the remaining time base unit If amplifier units are installed in both horizontal compartments an Alternate Puise is not produced since there are no time base units to produce a holdoff pulse 3 10 Z AXIS LOGIC The Z Axis Logic stage produces an output curren
2. LAT uitis 3 ew 4593 400 Figure 4 1 Color code for resistors and capacitors Maintenance 7904A LEAD CONFIGURATIONS AND CASE STYLES ARE TYPICAL BUT MAY VARY DUE TO VENDOR CHANGES OR INSTRUMENT MODIFICATIONS B CATHODE 8 PLASTIC CASED TRANSISTORS SIGNAL DIODE SINGLE DUAL PLASTIC POWER TRANSISTOR PIN NUMBER SEQUENCE PATH HIGHEST PIN 7 NUMBER INTEGRATED CIRCUITS Figure 4 2 Semiconductor lead configurations REV MAR 1985 ANODE ANODE CATHODE LIGHT EMITTING DIODE L E D P DARLINGTON TRANSISTOR 4593 401A Maintenance 7904A TABLE 4 1 Relative Susceptibility To Static Discharge Damage ES Relative Susceptibility Levels MOS or CMOS microcircuits or discretes or linear microcircuits with MOS inputs Most Sensitive ECL Schottky signal diodes Schottky TTL l JFETs A eee rina aaa a e TT Ya TTL Least Sensitive Voltage equivalent for levels 1 100 to 500 V 6 600 to 800 V 2 200 to 500 V 7 400 to 1000 V est 3 250V 8 900 V 4 500 V 9 1200 V 5 400 to 600 V discharged from a 100 pF capacitor through a resistance of 100 ohms components Servicing static sensitive assemblies or components should be performed only at a static free work station by qualif
3. Humidity Electrostatic Discharge Operating 0 to 15 kV with no performance degradation Nonoperating 0 to 20 kV with no instrument damage TABLE 1 5 Physical Characteristics Characteristics iatomislioo BEEN _ Ventilation Safe operating temperature maintained by electronically driven dc fan Finish j Anodized trontipansls BiuscVingt paint on aluminum cabinet Overall Dimensions Measured at Maximum Points See Figure 1 1 Height 13 6 inches 345 mm 12 0 inches 305 mm Length 22 7 inches 577 mm Net Weight Instrument without Plug ins 37 2 Ib 16 9 kg 1 10 General iInformation 7904A 0 69 SIHONI NI ONY SUALJINFTTHA NI 38n9id 301 3H V SNOISN3IWIG 3L0N Figure 1 1 7904 Dimensional Drawing 1 11 General information 7904A SYSTEM ELECTRICAL SPECIFICATION Your Tektronix 7904A Oscilloscope system provides exceptional flexibility in operation with a wide choice of and special purpose plug in units The type number of a particular plug in unit identifies its usage as follows The first digit 7 denotes the oscilloscope system for which the plug in is designed 7000 series The second letter describes the purpose of the plug in unit A Amplifier unit B Real time time base unit tracer D Digital unit L Spectrum analyzer M Misc
4. CER DI 150PF 54 200V 59660 855 535 U2J0151J 15 1 2284 283 0251 00 CAP FXD CER 01 87 5 100V 04222 3418 100A 8704 15 1 2297 281 0762 00 041952 CAP CER DI 27PF 20 100V 04222 MA101A270MAA A15A1C3440 281 0816 00 031801 CAP FXD CER 01 82 5 100 04222 106 820 AL5AICR2124 152 0141 02 SEMICOND DVC D1 SV S1 30V 150MA 30V D0 35 03508 2527 184152 15 1 82125 152 0141 02 SEMICOND DVC D1 SW S1 30V 150MA 30V 00 35 03508 DA2527 1N4152 ALSALCR2127 152 0141 02 010100 8029999 SEMICOND DVC D1 SW SI 30V 150MA 30V D0 35 03508 042527 1N4152 AL5A1CR2137 152 0141 02 030000 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 03508 DA2527 1N4152 AL5AICR2139 152 0141 02 030000 SEMICOND DVC DI SW ST 30V 150MA 30V 00 35 03508 DA2527 1N4152 1 1 2140 152 0141 02 010100 029999 SEMICOND DVC Di SW SI 30V 150MA 30V 00 35 03508 0 2527 1N4152 15 1 2141 152 0141 02 010100 8029999 SEMICOND DVC Di SW S1 30V 150MA 30V D0 35 03508 0 2527 1N4152 AL5AICR2142 152 0141 02 010100 8029999 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 042527 1N4152 ALSAICR2145 152 0141 02 SEMICOND DVC D1 SW S1 30V 150MA 30V D0 35 03508 2527 104152 AL5AICR2146 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 DA2527 104152 1 1 2153 152 0141 02 030000 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 042527 184152 AL5A1CR2158 152 0141 02 010100 8029999 SEMICOND DVC DI S
5. Check bandwidth and vertical channel isolation a TEKTRONIX SG 504 Leveled Sine Wave Generator with 8 High Frequency Sine Wave Generator Frequency 250 kHz to 1 GHz reference frequency 20 MHz or lower output amplitude variable from 0 5 to 4 volts into 50 amplitude accuracy within 196 of reference as output frequency changes SG 504 Output Head b Wiltron Model 610C Swept Frequency Generator with Model 61083C 10 to 1220 MHz piug in unit Provides access to supply Rigid Calibration Fixture voltages without removing Tektronix Part 067 0589 00 the 7904A power supply 9 Plug In Extender For 7000 series plug in 10 Signal Standardizer Produces gain check and Used throughout procedure a Tektronix Calibration pulse response waveforms to standardize 7904A so Fixture 067 0587 02 two needed that plug in units can be i b Tektronix Calibration interchanged without Fixture 067 0587 01 complete readjustment c Tektronix 7000 series plug in units with suitable signal sources may be sub stituted if lower performance is acceptable Used for Adjustment only not used for Performance Check 5 12 Checks and Adjustment 7904A TABLE 5 3 CONT Test Equipment Minimum Specifications Examples of Applicable Description Test Tam 11 Time Mark Generator Marker frequency 0 1 s to Check Adj
6. G READOUT SYSTEM 1 2 4 9 5 34 Readout System Preliminary Setup Adjust Readout Vertical Separation Centering and Character Height A15R2291 A18R737 A15R2273 A28R101 28 114 Adjust Character Scan A15R2128 Adjust Column and Row Match A15R2214 1582183 Check Readout Modes 1 ADJUSTMENT AND PERFORMANCE CHECK POWER UP SEQUENCE NOTE The performance of this instrument can be checked at any ambient temperature from 09 to 50 C unless otherwise stated Adjustments must be performed at an ambient temperature from 20 to 30 for the specified accuracies Check that the 7904A has been set for the proper power source and also that a suitable power cord and piug has been attached Refer to Power Source Information in Section 1 General Information for specific details 2 Remove cabinet paneis to gain access to internal adjust ments and test points For instruments with serial numbers below 040000 remove fan blade from motor by gently pulling blade off motor shaft 3 Connect the 7904A to a suitable power source 4 Press the POWER button and allow at least 20 minutes warmup before proceeding To prevent instrument damage turn off 7904A POWER before installing or removing plug in units REV JAN 1987 Checks Adjustment 7904A Part IIl Adjustment and
7. DI 10PF 105 100V CAP FXD CER DI 0 20 50V CAP FXD PLASTIC 0 027UF 5 100V CAP PLASTIC 0 0047UF 5 100V MICA 01 890 2 100V CAP MICA DI 105PF 1 300 CAP FXD PLASTIC 0 OLUF 5 1007 CAP VAR PLASTIC 2 22PF 100V FXD CER 01 0 1UF 20 50V CAP ELCTLT 22UF 50 10 25V ELCTLT 22UF 450 1025 25V CAP ELCTLT 22UF 450 10 25V DI LOPF 10 100V CAP CER 01 0 10 20 50 PLASTIC 0 027UF 5 100V FXD PLASTIC 0 0047UF 5 1007 CAP FXD MICA DI 890PF 2 100V CAP FXD MICA 105 1 300 CAP PLASTIC 0 O1UF 5 100V CAP VAR PLASTIC 2 22PF 100V CER 01 0 10 20 50V CAP FXD 01 0 20 50V FXD CER DI 470PF 10 100V CAP ELCTLT 47UF 50 10 16V SEMICOND DVC D1 SW ST 30V 150MA 30V D0 35 SEMICOND DVC DT SW 51 30 150MA 30V 00 35 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 COIL RF FIXED 2 7UH COIL RF FIXED 2 7UH COIL RF FIXED 2 7UH TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 7 TRANSISTOR NPN SI 10 18 TRANSISTOR NPN SI TO 18 TRANSISTOR NPN SI TO 18 TRANSISTOR NPN SI TO 18 TRANSISTOR NPN SI 70 18 TRANSISTOR NPN SI 70 18 TRANSISTOR NPN ST T0 18 TRANSISTOR NPN 51 0 18 TRANSISTOR PNP S1 T0 18 TRANSISTOR PNP SI
8. Midrange BEAMFINDER Pushbutton out CALIBRATOR 4 V pushbutton in Tos Equipment Controls Precision DC Voitmeter DVM Appropriate range for voltage to be measured 4593 411 a Setthe 4 V and 0 4 V CALIBRATOR pushbuttons to the pressed in position b Connect the precision dc voltmeter DVM to the CALIBRATOR output connector a DVM reading of 0 4008 volt within the limits of 0 4004 to 0 4012 volt B3 CHECK CALIBRATOR 1 kHz REPETITION RATE NOTE if the preceding step was not performed first perform step B1 then proceed B3 SETUP CONDITIONS 7904A Controls CALIBRATOR 4 V pushbutton in Test Oscilloscope CALIBRATOR Coaxial Cable 4 Externai Trigger Input BNC T Connector Coaxial Test Equipment Controls Time Mark Generator Test Osciloscope Triggering Input Coupiing Sweep Rate Vertical Mode 4593 412 Checks and Adiustment 7904A Part i Performance Check NOTE A frequency counter with an accuracy of at least 0 1 be used to check the CALIBRATOR repetition rate Connect 1 millisecond time markers to the test oscilloscope external trigger input and to the noninverting vertical channel of the test oscilloscope use a bnc T connector Connect the 7904A CALIBRATOR output to the inverting input of the test oscilloscope Set the test oscilloscope Triggering Level control for a stable time mark d
9. VERT MODE e 1 Midrange 8 HORIZONTAL MODE A ag amp Midrange ee TRIGGER SOURCE VERT MODE Test Equipment Controls POGUS PEOR Midrange READOUT OFF in detent Triggering GRAT ILLUM As desired BEAMFINDER Pushbutton out Signal Standardizer Vert or Horiz Gain 4593 422 a Position the signal standardizer display to align the bright center trace with the graticule center line b CHECK for one trace per graticule division within 0 05 division over the center six graticule divisions Note the exact error for comparison in part f c Remove the signal standardizer from the RIGHT VEHT compartment and install it in the LEFT VERT compartment d Set the VERTICAL MODE switch to LEFT e CHECK for one trace per graticule division within 0 05 division of the error noted in part b over the center 6 graticule divisions 5 26 CHECK VERTICAL LOW FREQUENCY LINEARITY NOTE If the preceding step was not performed first perform step E1 then proceed E3 SETUP CONDITIONS 7904A Controis VERTICAL MODE d E UG 5 S Time Test Equipment Controis Time Base Sweep Rate Q1 Triggering Auto AC internal Signal Standardizer 1 kHz
10. I Adjustment and Performance Check Then Adjustment and Performance Check proceed sequentially through subsections A B C etc to end Partial Part i Performance Check or Part H Adjustment and Performance Check by Subsection A B etc Partial Part Performance Check or Partial Part il Adiustment and Performance Check by Step A1 A2 B1 B2 etc within Subsection A B C etc Perform Power Up Sequence for Part I Performance Check or Part Adjustment and Performance Check Perform the Preliminary Control Settings instructions for the desired subsection Then proceed sequentially through the procedures in desired subsection Perform Power Up Sequence for Part 1 Performance Check or Part H Adjustment and Performance Check Perform the Preliminary Control Settings instructions for subsection A B C etc containing the desired step A1 A2 B1 B2 etc Then proceed through the instructions a b c etc in the desired step Although a partial adjustment procedure may be done we recommended that ihe entire subsection procedure be performed if any adjustments are made PERS MS USING THESE PROCEDURES These procedures are divided into subsections by major functional circuits e g A Power Supply B Z Axis And NOTE Display etc The order in which the subsections and In these procedures capital letters within the procedures appear is the recommended sequence fo
11. 6012 22526 48283 029 22526 48283 029 REV JUL 1987 Tektronix ent No Part No A28 670 1632 05 28 670 1632 06 28 100 290 0778 00 28 122 281 0792 00 A28C260 290 0745 00 28 300 281 0812 00 28 310 281 0123 00 A28C340 281 0123 00 28 350 281 0812 00 28 350 290 0745 00 28 420 281 0788 00 A28C430 283 0260 00 28 440 281 0788 00 A28C542 281 0773 00 A28C550 281 0773 00 A28C660 283 0003 00 A28CB10 281 0166 00 A28C811 283 0647 00 280811 283 0533 00 28 840 283 0547 00 280840 283 0633 00 28 850 281 0166 00 8 860 283 0005 00 A28C910 281 0773 00 A28C911 281 0659 00 28 920 281 0773 00 A28C922 281 0123 00 A28C930 283 0003 00 A28C931 283 0003 00 A28C943 281 0773 00 2 8 950 283 0003 00 28 950 281 0659 00 A28CR720 152 0141 02 A28CR740 152 0141 02 2825 131 1003 00 A28J6 131 1003 00 A28J12 131 1003 00 A28L150 108 0245 00 A28L161 108 0245 00 281 220 108 0578 00 281 230 108 0578 00 281942 108 0707 00 A28P59 131 0608 00 28 95 131 0608 00 A280140 151 0190 00 A280320 151 0221 00 A280321 151 0221 00 280330 151 0221 00 280340 151 0221 00 A289410 151 0220 00 A280420 151 0220 00 A280430 151 0220 00 280620 151 0220 00 280621 151 0434 00 280621 151 0434 01 REV JUL 1987 Serial Assembly No Effective Dscont 8010100 B010769 B021160 B021160 B010100 B010141 8010768 8010140 Replaceable Electrical Parts 7904A Mfr amp Des
12. are shown on the Character Selection Matrix see Fig 3 9 Each character requires two currents to define it these currents are identified as the column current and the row current corresponding to the column and row of the matrix The column and row data is encoded by programming the plug in units Figure 3 15 shows a typical encoding scheme using resistors for a voltage sensing amplifier plug in unit Notice that the 10 TS time siot pulses produced by the Time Slot Counter stage are connected to the plug in unit However time siots 5 6 and 10 are not used by the plug in unit to encode data when using the Standard Readout Format See Table 3 11 for Standard Readout Format The amplitude of the time siot pulse is exactly 15 volts as REV NOV 1985 determined by the Timer stage Therefore the resultant output current from the plug in units can be accurately controlled by the programming resistors in the plug in units For example in Figure 3 15 resistors R10 through R90 control the row analog data which is connected back to the Readout System Figure 3 16 shows an idealized Theory of Operation 7904A output current waveform of row analog data which results from the time slot pulses Each of the row current levels shown in these waveforms correspond to 100 microamperes of current The row numbers on the left hand side of the waveform correspond to the rows in the Character Selection Matrix see Fig 3 9 The row a
13. 10 SETUP CONDITIONS 7904A Controls F11 SETUP CONDITIONS VERTICAL MODE 7904A Controls 2 MODE VERTICAL MODE Time Base 5 a Signal Standardizer Test Equipment Controls Time Base Sweep Rate Triggering 2 j omi lt EH E E Test Equipment Controis Time Base Sweep Rate Amplifier H Defiection Factor 0 1 V div Triggering Input Coupling B Time Base Sweep Rate 1 ms div Trigger ng Auto AC Internal 4593 5447 Signal Standardizer Vert or Hor z Aux In 4593 543 a CHECK rotate the VERT TRACE SEPARATION a Position the trace to the upper half of the graticule area with the signal standardizer Position control Set the VERTICAL MODE switch to LEFT and position the trace to the lower half of the graticule area with the amplifier Position control CHECK for two traces in the ALT and CHOP positions of the VERTICAL MODE switch Set the VERTICAL MODE switch to ADD CHECK for a single trace that can be positioned vertically with either left or right vertical Position controls 5 68 B control throughout its range and check that the trace produced by the B time base unit can be positioned above and below the trace produced by the A time base unit by at least 3 5 divisions Repeat with the HORIZONTAL MODE switch set to ALT Checks and Adjustment 7904A Part H Adjustment and Performance Che
14. ADJUST B Gain adjustment R474 the 14 Trigger Selector Board for a test oscilloscope display of six divisions of deflection between the center seven traces within 0 6 division Remove the signal standardizer from the LEFT VERT compartment Set the test oscilloscope to alternate between channel 1 and channel 2 Re establish a ground reference for both channels of the test oscilloscope Then set both channels for dc coupling EXAMINE the test oscilloscope display for a dc level within 1 division 50 millivoits of the established ground references both traces ADJUST ihe B DC Common Mode adjustment R479 on the A14 Trigger Selector Board for dc levels within 1 division of ground both traces INTERACTION the adjustment of R479 R474 and R455 may interact Repeat step D3 if necessary 04 CHECK ADJUST VERTICAL SIGNAL OUT DC CENTERING A14R485 148480 A14R490 NOTE If the preceding step was not performed first perform step D1 then proceed D4 SETUP CONDITIONS 7904A Controls No change in settings Test Oscilloscope Coaxial Cable Test Equipment Controis Test Oscilloscope input Coupling Gnd or Off Vertical Deflection 0 5 V div Vertical Mode Channel 1 Sweep Rate 1 ms div Ew 4593 520 a Establish a ground reference for the test oscilioscope by positionin
15. CRBIAFXE 75 OHM A14R240 315 0100 00 RES FILM 10 OHM 535 0 25W 19701 5043CX10RR00J 148241 322 0114 00 RES FXD FILM 150 OHM 1 0 25W TC T0 75042 0 1500 148242 321 0202 00 RES FILM 1 24K OHM 172 0 125W TC TO 24546 5501241 A14R243 322 0111 00 RES FILM 140 OHM 125 0 25M TC TO 91637 MFF1421G140ROF A14R244 322 0170 00 RES FXD F1LM 576 OHM 124 0 254 TC TO 75042 CEBTO 5760F 148245 321 0202 00 RES FILM 1 24K OHM 125 0 125 TC TO 24546 5501241 A14R246 321 0147 00 RES FXD FILM 332 OHM 1 0 125W TC TO 07716 2 148247 315 0103 00 RES FXD FILM LOK 5 0 250 19701 5043 10 000 A14R248 321 0155 00 RES FXD FTLM 402 OHM 1 0 125W TC 10 07716 CEAD402ROF A14R250 317 0200 00 RES CMPSN 20 OHM 50 0 125W 01121 882005 14825 321 0218 00 RES FILM 1 82K OHM 176 0 125W TC TO 19701 5033EDIK82F 148252 321 0242 00 RES FXO FILM 3 24K 19 0 125W TC T0 19701 5043ED3K240F Ai4R254 315 0102 00 RES FILM 1K OHM 55 0 25W 57668 NTR25JEO1KO A14R255 311 1236 00 RES VAR NONW TRMR 250 OHM 0 SW 32997 3386 07 251 148256 321 0062 00 5 43 2 OHM 0 5 0 125W TC TO 57668 CRBi4 FXE 43 2 14826 321 0178 00 RES FXD FILM 698 1 0 125 TC TO 07716 CEADSS8ROF 148262 315 0510 00 RES FXD FILM 51 OHM 5 0 25W 19701 5043CX51R003 148263 322 0151 00 RES FXD FILM 365 OHM 1 0 25W
16. Plug On Boards Remove and replace the plug on boards as follows 1 Remove the power supply unit see Power Supply Unit Removal as necessary to gain access to the boards mounted on the rear of the A6 Main Interface board 2 Disconnect any end lead coaxial connectors located on the front of the board or those which pass across a portion of the board 3 Loosen all of the board s securing screws 4 Keeping the board parallel to the A6 Main interface board gently pull out on the edges of the board until the feed thru terminals are cleared 5 To replace a plug on circuit board position the board parallel to the A6 Main interface board so that all feed thru pins are properly aligned with their sockets 6 Gently press the circuit board against the mounting surface Be sure that all feed thru pins and sockets mate properly 7 Uniformly tighten the securing screws recommended torque four to six inch pounds 5 Switch Circuit Board Remove or replace the A5 Mode Switch circuit board as follows CAUTION KANAN urs gms rms as s gm Do not allow solder or solder flux to flow under printed circuit board switches The printed circuit board is part of the switch contacts and intermittent switch operation can occur if contaminated 1 Separate the Display Unit from the Acquisition Unit as previously described under Display Unit Kickstand 2 Remove the VERT TRACE SEPARATION B knob and extension shaf
17. 13 4449 315 0302 00 1384456 315 0821 00 1384461 321 0290 00 A13R4462 321 0246 00 AL3R4467 321 0290 00 AL3R4468 321 0246 00 1 470 315 0100 00 138447 321 0243 00 A13R4472 315 0242 00 A13R4473 315 0512 00 A13R4474 315 0512 00 13 4475 315 0151 00 13 4476 321 0243 00 A13R4477 315 0103 00 1384478 321 0205 00 1384480 315 0511 00 A13RA4481 315 0332 00 13 4482 321 0222 00 1384483 321 0222 00 1364484 315 0913 00 1 485 315 0201 00 13 4486 315 0152 00 1384487 315 0203 00 1354488 315 0752 00 A13R4489 315 0101 00 A13RA490 315 0102 00 1384491 315 0203 00 A13R4492 315 0102 00 A13R4493 315 0431 00 Ai3R4494 315 0911 00 A13RA496 315 0431 00 13 4498 315 0202 00 1354488 260 1811 00 13 4301 214 0579 00 13 4303 214 0579 00 13 7 4392 214 0579 00 13 4411 214 0579 00 Ai3TP4412 214 0579 00 137 4413 214 0579 00 137 4482 214 0579 00 REV JUL 1987 Serial Assembly No Effective _ Dscont Replaceable Electrical Parts 7904A Name amp Description RES FXD FILM 30K OHM 5 0 25W RES FXD FILM 1 2K OHM 5 0 25W RES FXD FILM 300 OHM 5 0 25W RES FILM 1K OHM 5 0 25M RES FXD FILM 2 OHM 55 0 25M RES FXD FILM 10 OHM 5 6 0 25W RES FXD FILM 3 3K OHM 52 0 25W RES FXD FILM 15K 54 0 25W RES FXD FILM 200 OHM 5 0 25W RES FXD FILM 5 1K OHM 5 0 25W RES FXD FILM 200 OHM 5 0 25W RES FXD 1 5 OHM 535 0 2
18. 2154 15 1 2159 15 17 2180 15 17 2199 15 1 2208 15 17 2211 15 1 2226 ALSALTP2232 15 17 2250 15 17 2251 15 1 2296 15 1 2299 15 102120 15 102126 15 102127 15 102127 15 102155 A15A1U2157 15 102159 15 102162 A15A1U2180 15 102185 15 102186 15 102190 A15A1U2202 A15A1U2202 15 102203 A15A1U2204 A15A1U2210 15 102232 15 102244 REV JUL 1987 Tektronix Part No 321 0335 00 321 0321 00 311 1225 00 321 0310 00 315 0132 00 321 0301 00 321 0245 00 321 0302 00 321 0255 00 321 0241 00 321 0251 00 315 0152 00 321 0254 00 315 0102 00 315 0203 00 315 0431 00 315 0241 00 260 0723 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 156 0043 03 155 0021 01 156 1172 01 156 1172 02 156 0043 03 156 0730 02 155 0017 00 156 0388 03 155 0015 01 155 0014 01 156 1177 01 155 0015 01 156 1172 01 156 1172 02 160 2997 00 156 0865 02 156 1191 00 155 0018 00 155 0014 01 Serial Assembly No Effective Dscont 8030000 8030000 B010100 B030000 8010100 8030000 8010100 8030000 8010100 8010100 8030000 8010100 030000 8010100 8030000 8010100 8031801 8010100 B010100 801010
19. 24546 24546 75042 19701 07716 57668 19701 19701 32997 32997 57668 19701 57668 57668 57668 01295 881005 CEAD 6100F NA65D 2870F 5033 0909 5033 01 5033EDIKA3F 5033 0806 CEAD26100F 9033ED604ROF 5033ED150ROF 6003320 8003320 NTR25J EO1K2 SO33ED1 KSOF CEAD280ROF CEBTO 1741F 5043RD1K210F 5033 016 20 CEADAGAROF CEAD107ROF 5043 62 002 NTR25J E470E NTR25J EO4K3 CMF55116G28RO00F CMF55116G28RO0F 5033ED12K70F 5033 015000 5033 015 00 5033ED15J00F CEAD61901F 5033 0453 SO33EDIKOOF CMF55116640201F 5033 020 00 252 03 0 NTR2SJEOLKO 5043CX1 5K00J CMF551 16G49R90F NTR25J E07K5 NTR25J EO1K2 CEAD12101F 5033ED21KO00F NAGSDGORBF NAGSDGORBF CECTO 1690F 5033ED10KOF CEAD23201F NTR25J EO4K7 S0430X3K600J 5043 3 6002 3386F T04 503 3386F T04 503 NTR25J E 20K 5043CX200K0J NTR253 E 100K NTR25J E220K 252 01 0 T8 1 8 500 7 47 Replaceable Electrical Parts 7904A Tektronix ent Part No A18TP300 214 0579 00 A18TP500 214 0579 00 A18TP502 214 0579 00 18 630 214 0579 00 A18TP700 214 0579 00 18 720 214 0579 00 A18TP721 214 0579 00 A18U100 156 1149 00 180335 156 1149 00 A18U415 155 0175 05 A18U515 155 0178 05 4180630 156 1149 00 4180700 156 0158 00 A18W402 131 0566 00 A18W410 131 0566 00 A18W420 131 0566 00 A18W421 131 0566 00 A18W510 131 0566 00 184530 131 0566 00 7 48 Serial Assembl
20. 252 01 0 NTR25J E750E NTR25J E750E NTR25JEO1KO NTR25J E750E NTR25J E750E NTR2SJEO1KO 252 750 NTR25J E750E NTR25JEO1KO NTR25J E750E NTR25J E750E 5043CX51 0ROJ 50430X510R0J 50430X510R0J 010202 5033ED5K230F CEAD56201F 3386 04 501 GFO6LT 500 5033ED5K230F 4310R 101 472 25 01 0 NTR253 E51K0 5033 049 90 5043CX13K00J 5033ED 37K40F 5043CX13K00J 5033ED15J00F NTR25J E75K0 5033ED7 5K00F CEAD 15801F 16901 NTR25J ES1KQ 5033 49 90 5033ED20K50F CEAD21501F 4 NTR25J E150K NTR25J E470E 14 1 NTR25J E1K8 REV JUL 1987 Tektronix Serial Assembly No Mfr Component No Part No Effective _ Dscont amp Description Code Mfr Part No AL5A1R2203 321 0344 00 8 010100 8029999 RES FXD FILM 37 4K OHM 175 0 125W TC TO 19701 5033 37K40F AL5A1R2203 315 0511 00 8030000 RES FILM 510 OHM 5 0 25W 19701 5043 510800 15 162204 321 0335 00 010100 8029999 RES FILM 30 1K 10 0 1250 TC TO 57668 RBIAFXESOKi 15 152204 307 0446 00 8 030000 RES NTWK 10 OHM 20 9 RES 11236 750 101 15 1 2206 315 0513 00 8 010100 8029999 RES FILM 51K 5 0 250 57668 252 15 162206 321 0376 00 8030000 RES FXD FILM 80 6K 12 0 1258 TC TO 19701 5043 080 60 A15A1R2207 315 0154 00 8010100 8029999 RES FILM 150K OHM 525 0 25M
21. 5 Set both amplifier units to the same deflection factor Set the deflection for approximately six divisions of vertical and hori zontal deflection Time Base Unit Triggering 22 2 2 22 SOUICO l SVOL a cauia UY Trig d light on 4593 20 Figure 2 5 Typical Setup for X Y Displays with Z Axis Control from time base unit to the horizontal specifications in this manual and to the individual instruction manuals for the amplifier units Some of the 7B series time base units can be operated as amplifiers in addition to their normal uses as time base generators This feature allows an external signal to provide the horizonta deflection to the crt For most of the time base units with the amplifier function the X horizontal deflection signal can be connected either to an external input connector on the time base unit or it can be routed to the time base unit through the internal triggering system see time base manuals for details the latter method is used the and B TRIGGER SOURCE switches must be set so that the X horizontal deflection signal is obtained from one of the vertical amplifier units and Y vertical deflection signal is obtained from the other vertical unit The attenuator switch on the amplifier unit can provide the horizontal with a preconditioned signal
22. 7 40 REV JUL 1987 Tektronix ent No Part No 16 670 4769 20 A16C505 281 0811 00 A16C508 281 0775 00 A16C512 285 0650 00 A18C515 285 0643 00 Ai6C520 283 0666 00 16 525 283 0649 00 16 531 285 0598 00 A18C538 281 0204 00 A16C539 281 0775 00 A16C582 290 0745 00 A16C583 290 0745 00 16 584 290 0745 00 A16C605 281 0811 00 A16C608 281 0775 00 A16C612 285 0650 00 16 615 285 0643 00 16 620 283 0666 00 Al6C625 283 0649 00 A16C631 285 0598 00 A16C638 281 0204 00 A16C639 281 0775 00 A16C675 281 0775 00 18 581 281 0788 00 18 695 290 0746 00 ALBCR552 152 0141 02 16 8651 152 0141 02 16 8654 152 0141 02 161 582 108 0538 00 161 583 108 0538 00 A15L584 108 0538 00 16 680 131 0608 00 Al60542 151 0302 00 A160548 151 0302 00 160556 151 0302 00 160558 151 0302 00 A16Q642 151 0302 00 150648 151 0302 00 A180656 151 0302 00 180658 151 0302 00 180672 151 0301 00 A180678 151 0134 00 A160682 151 0301 00 168501 321 0289 00 168502 321 0289 00 168504 321 0335 00 168505 321 0335 00 168511 321 0414 00 168512 311 1214 00 168513 321 0318 00 Al6R5i4 321 0385 00 188515 311 1235 00 4168516 321 0309 00 15 519 321 0385 00 168520 311 1232 00 168521 321 0281 00 A16R524 321 0357 00 REV JUL 1987 Serial Assembly No Effective _ Dscont Name amp Description Replaceable Electrical Parts 7904 Mfr Code Mfr Part No CIRCUIT BD ASSY VERTICAL CHANNEL SWITCH CAP
23. 7904 instruction OPERATORS SAFETY SUMMARY The general safety information in this part of the summary is for both operating and servicing personnel Specific warnings and cautions will be found throughout the manual where they apply but may not appear in this summary TERMS IN THIS MANUAL CAUTION statements identify conditions or practices that could result in damage to the equipment or other property WARNING statements identify conditions or practices that could result in personal injury or loss of life AS MARKED ON EQUIPMENT CAUTION indicates a personal injury hazard not immediately accessible as one reads the marking or a hazard to property including the equipment itself DANGER indicates a personal injury hazard immediately accessible as one reads the marking SYMBOLS IN THIS MANUAL 9 Static Sensitive Devices This symbol indicates where applicable cautionary or other information is to be found AS MARKED ON EQUIPMENT DANGER High voltage D Protective ground earth terminal VN ATTENTION Refer to manual WARNINGS POWER SOURCE This product is intended to operate from a power source that will not apply more than 250 volts rms between the supply conductors or between either supply conductor and ground protective ground connection by way of the grounding conductor in the power cord is essential for safe operation GROUNDING THE PRODUCT This product is grounded through the groundi
24. FILM 240 OHM 5 0 25W 19701 SWITCH SLIDE DPDT 0 5A 125VAC 79727 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80008 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80008 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 TERM TEST POINT BRS CD PL 80009 MICROCKT DGTL QUAD 2 INP NOR 5 18324 MICROCKT DGTL SCAN OSCILLATOR amp LOGIC 80009 MICROCKT DGTL DUAL 4 BIT BIN CNTR SCRN 01295 MICROCKT DGTL DUAL 4 STAGE BIN CNTR SCRN 04713 MICROCKT DGTL QUAD 2 INP NOR GATE SCRN 18324 MICROCKT DGTL QUAD 2 INP NOR BFR SCRN 01295 MICROCKT DGTL BCD DECIMAL 80009 MICROCKT DGTL DUAL D FLIP FLOP SCRN 01295 MICROCKT DGTL ANALOG DATA SWITCH 80009 MICROCKT DGTL A D CONVERTER 80009 MICROCKT DGTL STET LINE PRIORITY ENCODER 01295 MICROCKT DGTL ANALOG DATA SWITCH 80009 MICROCKT DGTL DUAL 4 BIT BIN CNTR SCRN 01295 MICROCKT DGTL DUAL 4 STAGE BIN CNTR SCRN 04713 MICROCKT DGTL 4096 X 8 EPROM PRGM 80009 MICROCKT DGTL OCTAL D FF W CLEAR SCRN 01
25. Figure 3 17 Typical output waveforms for Zeros Logic and Memory stage operation at pin 7 of U2232 3 35 Theory of Operation 7904A an output to result in a being displayed The activated Character Generator provides current output for the Format Generator to produce the selected character on the crt In a similar manner any of the characters shown in the Character Selection Matrix can be displayed by correct addressing of the row and column DECIMAL POINT LOGIC AND CHARACTER POSITION COUNTER Decimal Point Logic and Character Position Counter U2260 performs two functions The first function is to add a staircase current to the X horizontal signal to space the characters horizontally on the crt After each character is generated the negative going edge of the Ready signal at pin 5 advances the Character Position Counter This produces a current step output at pin 3 which when added to the X signal causes the next character to be displayed one character space to the right This stage can also be advanced when a Space instruction is encoded so a space is left between the displayed characters on the crt Row 10 information from the Row Decoder is connected to pin 4 of U2260 When row 10 and column 0 are encoded the output of this stage advances one step to move the next character another space to the right However under this condition no display is produced on the crt during this time slot since the Character Gener
26. SWEEP 1 READY SINGLE SWEEP RESET INPUT CONVERTER RECTIFIERS T LOW gt VOLTAGE REGULATORS FAN Figure 3 1 Basic block diagram of the 7904A Oscilloscope OPERATING VOLTAGES TO CIRCUITS PROBE POWER The Focus Amplifier provides control voltages to maintain optimum focus of the crt display The Crt Circuit contains the control circuits necessary for operation of the crt The Display Control circuitry provides front panel INTENSITY and other crt controls The Calibrator circuit produces a one kilohertz square wave signal which can be used to check the calibration of this instrument and the compensation of probes The calibrator signal is available as a voltage at the CALIBRATOR connector or as a current through a 40 miliampere optional current loop accessory The internal trigger signals from the vertical plug in units are connected to the Trigger Selector circuit The Trigger Selector circuit determines whether the trigger Theory of Operation 7904A signal from the left or right vertical unit is connected to the A or B horizontal unit The B Trigger Channel Switch also produces the drive signal for the SIG OUT circuit to provide an output that is a sample of the vertical signal The Signals Out circuit processes signals from the plug in units for the front panel GATE and SAWTOOTH outputs The intensity Limiter circuit converts Intensity Limit current from the crt
27. The Calibrator circuit provides voltage outputs of 40 millivoits 0 4 volt and 4 volts at the CALIBRATOR output connector A current output of 40 milliamperes is available from the Calibrator circuit with an optional current loop adapter When using the current loop adapter the Calibrator must be operated only in the 4 V switch position for stated output Transistors Q376 and Q382 form a 1 kilohertz square wave oscillator Oscillation occurs as follows Initially assume that Q376 is conducting and Q382 is not conducting The voltage at the emitter of Q382 becomes more negative as C376 discharges through R381 Capacitor C376 discharges until the emitter base junction of Q382 becomes forward biased As Q382 begins conducting the oscillator changes states Regeneration starts when 0382 conducts and C376 stops discharging this reduces the coliector current of Q376 Thus the collector voltage of Q376 rises positive which causes the base and emitter of Q382 to rise positive The positive going voltage is coupled by C376 to the emitter of Q376 turning it off At this time Q382 is conducting and Q376 is not conducting The voltage at the emitter of Q376 goes negative as C376 charges through R376 When the emitter base junction of Q376 becomes forward biased the oscillator will again change states to complete the cycle The square wave signal produced at the collector of Q382 switches Q384 on and off When Q384 is on the current from R383
28. 20 127 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 20 156 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A20U21 152 0716 00 SEMICOND DVC DI HV MULTR SI 3KV PP IN 21KV 60211 VMi64 DC OUT A20U123 156 0087 12 010100 010784 MICROCKT LINEAR OPERATIONAL AMPLIFIER 01295 UA741CJG A20U123 156 0067 01 8010785 8041970 MICROCKT LINEAR OPNL AMPL CHECKED 04713 1741 105 8200123 156 0067 00 8041971 MICROCKT LINEAR OPNL AMPL SEL 04713 MC1741CP1 20 851 152 0247 00 SEMICOND DVC DI ZEN S1 150V 52 0 4v DO 7 04713 SZG275KIRL 7 62 REV JUL 1987 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr Component No Part No Effective Dscont Name amp Description Code Mfr Part No A21 70 5834 20 8010100 B021636 CIRCUIT BD ASSY Z AXIS 80009 670 5834 20 A21 670 5834 21 8001537 CIRCUIT BD ASSY Z AXIS 80009 670 5834 21 A2iC2 283 0003 00 CAP 01 0 80 20 150V 59821 D103740Z5UJDCEX A21C3 281 0773 00 CAP FXD CER DI 0 Q1UF 10 100V 04222 201 103 21 4 290 0539 00 CAP ELCTLT 47UF 20 20V 05397 T110C476MO20A5 21 6 281 0773 00 CAP DI 0 01UF 10 1007 04222 201 103 A21C7 281 0773 00 CER DI 0 01UF 102 100V 04222 201 103 42108 283 0177 00 DI 80 20 25V 04222 58302 1057 21 9 283 0059 00 DI 80 20 50
29. 5 20 Checks and Adjustment 7904A Part Check C TRIGGER SYSTEM un mg an J Aeae eer Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 1 Test Oscilloscope 2 or 3 Amplifier 4 Time Base two required C1 TRIGGER SYSTEM PRELIMINARY SETUP a Perform the Performance Check Power Up Sequence b Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure C Set the 7904A controls as follows POWER SWIC ciet TUS On VERTICAL RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE A INTENSITY Fully counterclockwise HORIZONTAL MODE A B Fully counterciockwise B TRIGGER SOURCE VERT MODE FOGUS Th cud vbt Midrange READOUT INTENSITY OFF in detent GRAT Midrange BEAMFINDER Pushbutton out 10 Signal Standardizer 13 Coaxial Cable C2 CHECK VERTICAL SIGNAL OUT DC CENTERING NOTE First perform step C1 then proceed C2 SETUP CONDITIONS D e TTT LII jill Coaxial Cable 7904A Controls No change in settings Test Equipment Controis Test Oscilloscope input Coupling Gnd or Off Vertical Deflection 0 5
30. 5K OHM O 5W 32997 3329 158 502 2171 321 0334 00 010100 B021636 RES FXD FILM 29 4K OHM 156 0 125W TC TO 07716 CEAD2940iF AZ1R71 321 0336 00 8021637 RES FXD F1LM 30 9K 0 1 0 125 1 0 19701 5043 030 90 A21R72 321 0231 00 RES F1LM 2 49K 0HM 19 0 125W TC TO 19701 5033 02 821873 321 0410 00 RES FXD FILM 182K OHM 14 0 1254 TC TO 19701 5033 0182 A21R75 315 0753 00 RES FILM 75K 5 0 25 57668 NTR25J E75KO0 A21R76 321 0260 00 RES FXD FILM 4 99K 1 0 12584 70 19701 5033ED4K990F A21R77 315 0132 00 RES FXD FILM 1 3K 5 0 25 57668 NTR25J EO1K3 21 79 315 0473 00 RES FILM 47K 5 0 25 57668 NTR25J E47KO A21RB8l 315 0103 00 RES FILM 10K OHM 5x 0 25W 19701 5043 10 002 21882 315 0391 00 RES FILM 390 5 0 259 57668 252 390 A21R83 315 0101 00 RES FXD FILM 100 0HM 55 0 25W 57668 NTR25J E 100E 7 54 REV JUL 1987 ent No A21R101 A21R109 21 10 21 111 A21R113 A21R121 21 122 A2iR123 A 21R124 218105 A21R126 A21R127 21 128 21 123 218132 A21R133 21 134 21 135 21 135 A21R143 216150 21 155 A21R156 21 161 A21R162 A21R166 A21R167 A21R168 21 169 218171 218172 218173 A21R176 A21R177 A21R179 21 180 A21R183 AZiTP32 21 83 21 122 21 143 211 183 A21TP186 21 186 21 186 REV JUL 1987 Tekt
31. 72982 0301000 Y5EO101J 21 156 281 0798 00 021637 FXD CER 01 51 1 100 04222 MALGIA510GAA 21 169 283 0211 00 CAP 01 0 1UF 105 200V 04222 SRAQG6CIO4KAA 21 171 290 0149 00 FXD ELCTLT 50 75 10 150V 00853 5560005001508 21 172 283 0770 00 MICA 01 300 PF 1 500V 00853 Di55F301F0 21 179 281 0619 00 CAP FXD CER 01 1 2 0 1 500V 52753 2RDPLZ007 1 208 A21C180 281 0092 00 CAP VAR D1 9 35PF 200V 33095 53 717 001 09 35 A21C183 281 0773 00 CER DI 0 01UF 105 100V 04222 201 103 A21C186 281 0609 00 CAP CER DI 1PF 0 1PF 500V 52763 2RDPLZOO7 1POOBC 21 832 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 184152 A21CR35 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 0 2527 1 4152 A21CR36 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 0DA2527 1N4152 21 837 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 DA2527 1N4152 A21CR39 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 DA2527 1 4152 AZICR43 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 03508 DA2527 1 4152 A21CR64 152 0141 02 SEMICOND DVC D1 9W SI 30V 150MA 30V D0 35 03508 DA2527 1N4152 21 865 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 03508 DA2527 184152 A21CR76 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 DA2527 184152 21 882
32. A8P13 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 REV JUL 1987 7 17 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr t No Part No Effective Dscont Name amp Description Code Mfr Part No A9 670 8054 00 CIRCUIT BD ASSY FRONT PANEL DISPLAY 80009 670 8054 00 A9P11 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A9P12 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 131 1149 00 BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 ASR81 317 0510 00 RES FXD CMPSN 51 OHM 5 0 125W 01121 885105 ASR82 317 0510 00 RES FXD CMPSN 51 OHM 5 0 125W 01121 5105 7 18 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr nt No Part No Effective _ Dscont Name amp Description Code Mfr Part No 10 670 8055 00 CIRCUIT BD ASSY FRONT PANEL DISPLAY 80008 670 8055 00 10 11 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 10 12 131 1149 00 CONTACT ELEC CKT BD BRZ SIL PL 80009 131 1149 00 F QUANTITY OF 2 A10P13 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A10R6l 317 0510 00 RES FXD CMPSN 51 OHM 5 0 125W 01121 885105 10862 317 0510 00 RES FXD CMPSN 51 5 0 1254 01121 885105 REV JUL
33. CIRCUIT BD ASSY READOUT CIRCUIT BD ASSY READOUT PART OF 672 0572 XX CAP FXD CER 21 0 02 80 20 150V CAP FXD CER 01 0 022MFD 20 100V CAP FXD CER DI Q O1UF 80 2025 150V FXD DI 0 01UF 10 100V CAP FXD CER DI 330PF 5 500V CAP FXD CER D1 330PF 2075 100V CAP FXD ELCTLT 4 7UF 75 10 35VDC CAP FXD ELCTLT LOUF 50 1075 25V CAP FXD ELCTLT 4 7UF 75 10 35V0C CAP FXD ELCTLT 33UF 50 1006 35V CAP FXD ELCTLT 10UF 450 1075 25V CAP FXD ELCTLT 4 7UF 75 10 35VDC DI 0 001UF 80 20 100V FXD MICA 01 0 001 1 100 FXD CER DI 0 01UF 10 100V FXD CER D1 0 01UF 10 100V CAP FXD PLASTIC 0 O082UF 5 100V CAP FXD CER 1 180 5 500 CAP FXD CER 01 330 20 100V FXD CER 01 5 6 0 5 100 FXD ELCTLT 4 70 75 10 35VDC CAP FXD MICA DI 110PF 1 100V CAP FXD MICA DI 120PF 1 500V CAP FXD MICA DI 100PF 5 500V C2154 IS SELECTABLE CAP 180 5 500 CAP VAR CER DI 7 45PF 25V FXD CER DI 0 01UF 1075 100V FXD CER 01 100 5 100 FXD CER 01 0 010 10 100 CAP CER 01 470 5 500V CAP DI 470PF 10 100V FXD CER 01 0 02UF 480 204 150V CAP FXD CER 01 0 022 0 20 100 CAP FXD CER 01 0 010 10 100V FXD CER 01 0 001UF 80 2
34. M i T i 4 i i i i i i M i i i A HORIZ CHANNEL 2 LEFT VERT RIGHT VERT CHANNEL 2 CHANNEL 2 B HORIZ CHANNEL 2 1675 8 2314 8 Figure 3 8 Location of readout display on the crt identifying ihe originating plug in and channel 3 23 Theory of Operation 7904A 85 660 NI NOILLdIHOSIG H3lOVHVHO 1VINIO3O 33S H310VHYVHO LNIOd TWIAID3G LNIOd SS3HGGV TVNOILVta3dO W3iSAS LNOGVSY JO NOISNVdX3 318VTlIVAV SNOTEVOO1 O3Sn ND iNIOd ANIOd YAA IVWIO3Q Xidatd Av1dsta m MOY S2uadNV AiN3uuno inr d NANTO Figure 3 9 Character selection matrix for 79044 Readout System SN B031766 amp Below REV NOV 1985 3 24 1676 20 Figure 3 10 Typical readout display where only channel 2 of the Right Vertical and B Horizontal units is displayed provided for special instructions to the Readout System The unused locations in the Matrix shaded area are available for future expansion of the Readout System The method of addressing the locations in the Character Selection Matrix is described in the following discussion DEVELOPING THE DISPLAY This description is intended to relate the basic function of each stage to the operation of the overall Rea
35. REV JUL 1987 Tektronix Part No 317 0103 00 321 0246 00 321 0309 00 315 0272 00 321 0277 03 321 0277 03 315 0471 00 315 0102 00 307 0053 00 321 0279 00 321 0322 00 315 0562 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 156 1149 00 156 1149 00 156 1149 00 156 1149 00 155 0173 05 156 0067 00 156 0067 00 Serial Assembly No Effective Dscont Replaceable Electrical Parts 7904A Name amp Description RES FXD CMPSN 10K OHM 5 5 0125W RES FXD FILM 3 57 OHM 15 0 125W TC TO RES FXD FILM 15 2 OHM 12 0 1254 0 RES FILM 2 7K OHM 5 0 25W RES FXD FILM 7 50K OHM 0 25 0 1254 T T2 RES FXD FILM 7 50K OHM 0 25 0 125W T T2 RES FILM 470 OHM 5 0 25W RES FXD FILM IK OHM 5 0 25W RES FXD CMPSN 3 3 OHM 5 0 SW RES FILM 7 87K OHM 12 0 1254 TC TO RES FXD FILM 22 1K OHM 0 1 0 125W TC TO RES FXD FILM 5 6K OHM 5 75 0 25W TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD
36. Replaceable Electrical Parts 7904 8151900 4151905 151910 8151915 A151920 A191924 8151930 151940 17 1908 ALTP1925 ALTP1952 ALTP1958 AlU1952 AiU1958 A1VR1910 7 8 Tektronix Serial Assembly No Mfr Part No Effective Dscont Name amp Description 5 Code Mfr Part No PART OF 1900 260 1380 00 SWITCH PUSH 2 BUTTON 2 POLE STORAGE LOGIC 59821 2 020000619 PART OF 151905 260 1380 00 SWITCH PUSH 2 BUTTON 2 POLE STORAGE LOGIC 59801 2 8 020000619 eee PART OF A151915 181924 260 1208 00 SWITCH PUSH DPDT 28VDC PUSH PUSH 31918 ORDER BY DESCR 260 1208 00 SWITCH PUSH DPDT 28VDC PUSH PUSH 31918 ORDER BY DESCR 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 156 0686 00 MICROCKT LINEAR MOS OPNL AMPL 02735 1305 156 0067 00 MICROCKT LINEAR OPNL AMPL SEL 04713 MCI741CP1 152 0280 00 SEMICOND DVC DT ZEN S1 6 2V 55 0 4v DO 7 04713 1 753 REV JUL 1987 Tektronix nt No Part No A2 570 5227 01 A2CR2009 152 0141 02 A2CR2019 152 0141 02 2 2003 131 0608 00 2 2005 131 0608 00 2 2006 131 0608 00 A2R2005 311 1973 00 2 2007 315 0622 00 A2R2008 315 0303 00 A2R2009 321 0193 00 A2R 010 311 1375 00 A2R2015 311 1372 00 A2R2016 315 015
37. Replaceable Electrical Parts 7904 7 50 Tektronix ent No Part No A20 670 5841 20 8010100 A20 670 5841 21 021130 A20C9 283 0068 00 A20C10 283 0068 00 A20C11 283 0068 00 A20C22 283 0111 00 20 33 283 0078 00 20 34 283 0068 00 A20C36 283 0271 00 A20C39 283 0271 00 A20C42 283 0271 00 20 53 283 0279 00 A20C64 283 0092 00 A20C66 283 0271 00 20 69 283 0271 00 20 72 283 0271 00 A20C82 283 0105 00 20 84 283 0272 00 20 86 283 0272 00 20 87 283 0105 00 A20C89 283 0272 00 20 91 283 0272 00 A20C103 290 0767 00 20 104 290 0767 00 20 112 281 0593 00 A20C119 283 0271 00 A20C122 283 0000 00 A20C127 283 0000 00 A20C143 283 0068 00 A20C144 283 0068 00 A20C156 283 0068 00 20 159 283 0068 00 A 0CR17 152 0242 00 A20CR18 152 0242 00 2 19 152 0242 00 A20CR33 152 0242 00 20 834 152 0242 00 A20CR37 152 0242 00 20 838 152 0242 00 2 51 152 0242 00 20 863 152 0242 00 A20CR64 152 0242 00 A20CR67 152 0242 00 20 868 152 0242 00 20 882 152 0639 00 20 883 152 0539 00 20 8101 152 0586 00 20 8102 152 0586 00 20 8113 152 0242 00 20 8114 152 0242 00 20 124 152 0242 00 20 8126 152 0242 00 20 8129 152 0066 03 200545 150 0035 00 200546 150 0035 00 200547 150 0035 00 A20DS75 150 0035 00 200576 150 0035 00 Serial Assembly No Effective Dscont 8021129 Name amp Description CIRCUIT BD ASSY HV CIRCUIT BD ASSY HV CAP FXD CER D
38. SEMICOND DVC DI DUAL RECT SI 30A 20V TO 3 SEMICOND DVC DI SIG GE 60V GOMA A38A 14433 SEMICOND DVC DI SI SCHOTTKY 20V 1 2PF DO 35 21847 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 SEMICOND DVC D1 5W 1 30V 150MA 30V D0 35 61409 2 1582 03508 93508 042527 104152 042527 1M4152 COIL RF FIXED 1740 COIL RF FIXED 174UH COIL RF FIXED 27UH COIL RF FIXED 27UH COIL RF FIXED 174UH COIL RF FIXED 12UH TERMINAL 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 4 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 4 TERMINAL 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 5 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 7 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 6 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANITY OF 4 TRANSISTOR NPN SI 70 18 TRANSISTOR SELECTED TRANSISTOR SELECTED 2N3904 TRANSISTOR NPN SI TO 92 TRANSISTOR SELECTED 2N3904 TRANSISTOR NPN SI TO 92 TRANSISTOR SELECTED TRANSISTOR PNP ST T0 92 TRANSISTOR SELECTED TRANSISTOR PNP ST TO 92 RES FILM 5 1K OHM 5 0 25W RES FXD FILM 75K OHM 525 0 25V RES FXD FILM 200 OHM 555 0 25W RES FXD FILM 5 6K OHM 5 0 25W RES FXD FILM 220 OHM 5 0 25W RES FXD FILM 12K 545 0 25W RES FXD FILM 300 OHM 5 5 0 25W RES FXD FILM 47 OHM 51 0 258 RES FXO FILM 1K 5 0 25 RES FXO FILM 2K OHM 5 0 25W TK2042 TK2042 TK13
39. ULBIVAR7TAAANA D155F111F0 D155F121F0 0105F101J0 200H73L181J 518 006 G 7 45 MA201C103KAA 101 101 201 103 831 000 25E0471J MA101C471KAA 855 55825 02032 201 223 MA201C103KAA 101 107 MA201C103KAA 805 534 Y5D0152J 201 103 201 103 201 103 MA101A270MAA D151F89160 0155 161 0 831 000 25E0471J 101 471 101 471 831 610 Y5UO102P MA201C103KAA 855 55825 02032 201 223 201 10 7 93 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr Component No Part No Effective Dscont Name amp Description Code Mfr Part No 15 1 2246 281 0773 00 B030000 CAP 01 0 010 10 100 04222 201 A15A1C2251 281 0773 00 030000 CAP D1 0 01UF 10 100V 04222 201 103 A15A1C2255 283 0000 00 8010106 8029999 CAP CER DI 0 001UF 100 075 500V 59660 831 610 Y5UO102P A15A1C2259 281 0762 00 8041952 CAP DI 27PF 20 100V 04222 101 270 A15A1C2263 281 0773 00 8030000 CAP CER DI 0 01UF 10 100V 04222 201 103 A15A1C2276 281 0762 00 8030000 CAP FXD CER D1 27PF 205 100V 04222 MA101A270MAA A15A1C2277 283 0666 00 B030000 CAP MICA D1 890PF 2 100V 00853 0151 89160 A15A1C2279 283 0640 00 B030000 CAP MICA DI 180PF 1 100V 00853 0155 161 0 A15A1C2281 283 0054 00
40. allows the prefix to be shifted from m 100 microamperes of column current column 1 to no prefix 0 column current column 0 so only the unit of measurement encoded during time siot 9 is displayed Notice that reducing the prefix program from column 1 to column 0 programs the Readout System to not display a character at this readout location A further feature of the Zeros Logic and Memory is the Identify function If 10 units of column current are encoded by the plug in unit along with row 3 during time slot 1 the Zeros Logic and Memory produces negative going output pulse at pin 1 to switch the Column Data Switch and Row Data Switch to the ninth channel Then time siot pulses 2 through 9 encode output current through resistors R2191 and R2199 for column data and R2201 and R2209 for row data This provides the current necessary to display the word IDENTIFY in the word position allotted to the channel that originated the Identify command After completion of this word the Column Data Switch and Row Data Switch continue with the next word in the sequence The Word Trigger signal from the Word Trigger stage is connected to pin 9 of U2232 through C2242 At the end of each word of readout information this pulse goes LO This erases the four memories in the Zeros Logic and Memory in preparation for the data to be received from the next channel CHARACTER GENERATOR The Character Generator stage consists of five similar in
41. coded for identify column 10 row 3 this stage produces an output level connected with the Row Decimal to BCD Converter and the Row and Column Data Switches This output level connects the Column Data Switch with a coding network within the Readout system to produce an analog current during time slots 2 through 9 The current is then converted to Binary Coded Decimal and combined with the Row Decimal to BCD Converter output to address locations within the Character Generator necessary to display IDEN TIFY on the CRT The Zeros Logic and Memory stage is reset after each word by the End of Word pulse Each character displayed on the CRT consists of a series of connected points within an 8 point by 8 point grid The Character Generator contains grid locations of the points required to create any of the 50 possibile characters shown in the Character Selection Matrix of Figure 3 20 The row and column data encoded during a time siot are converted to BCD and used to address a location within the Character Generator containing the first grid point of the character to be displayed The 4 bit binary output from the Lower Order Address Generator is combined with the address created by the row and column data to provide the other grid points necessary to complete the character Only one character is addressable in any one time siot or a space can be added into the displayed word by the Horizon tal Character Position Counter stage when encoded by t
42. eee Sanat Sand LAAMA mene i TIME SLOT PULSE 4 PIN 11 TIME SLOT PULSE 5 PIN 10 TIMESLOT PULSE 6 TIME SLOT PIN 9 PULSE 7 PIN 7 TIMESLOT PULSE 8 PIN 6 TIME SLOT PULSE 9 PIN 5 TIME SLOT 0 PULSE 10 d ie PIN 4 NOTE TEST OSCILLOSCOPE EXTERNALLY TRIGGERED FROM TIME SLOT 1 SWEEP RATE UNCALIBATED Figure 3 14 Timer relationship of the time stot TS pulses produced by U2159 3 29 Theory of 7904 Slot Counter LO This resets the Time Slot Counter to time siot 1 and holds it there unti the Word Trigger is reset At the same time a level is applied to pin 4 of the Timer through CR2157 and CR2125 This level causes the Timer to operate in the Display Skip mode SO a character is not generated The next Trigger pulse is not recognized by the Time Slot Counter since U2159 is locked in time slot 1 by U2155 However this Trigger pulse resets the Word Trigger stage through C2155 Pin 18 of U2155D goes LO to enable the Time Slot Counter and Timer stages for the next time siot puise Simultaneously when U2155D switches output states the resulting negative going edge is connected to pin 3 of U2155A This results in a negative going Word Trigger output at pin 4 of U2155B to advance the Channel Counter to the next word When the next Trigger pulse is received at
43. 00853 D155E700F0 00853 D155E770F0 74970 187 0109 055 04222 SR3O03E1037AA 04222 MA201C103KAA CAP FXD CER 01 4 0 25 500V 52763 RDPLZOO7 4P30CC CAP FXD DI 0 01UF 1075 100V CAP VAR CER 81 5 25 100V CAP FXD CER DI 0 01UF 480 204 1500 CAP FXD CER 01 0 01UF 480 2025 150V CAP FXD CER DI 0 01UF 10 1007 CAP FXD CER DI 0 OLUF 80 20 1507 04222 MA201C103KAA 59660 518 00045 25 59821 D10374075UJDCEX 59821 D10324075UJDCEX 04222 201 103 59821 0103740750 0 CAP D1 4 3PF 4 0 25PF 500V 52763 2RDPLZOO7 4 30 SEMICOND DVC DI SW S1 30V 150MA 30V DO 35 03508 DA2527 1N4152 SEMICOND DVC DI 5W S1 30V 150MA 30V D0 35 03508 DA2527 1N4152 CONN RCPT ELEC CKT BD MT 3 PRONG CONN RCPT ELEC CKT BD MT 3 PRONG CONN RCPT ELEC CKT BD MT 3 PRONG CHOKE RF FIXED 3 9UH CHOKE RF FIXED 3 9UH COIL RF FIXED 19NH COIL RF FIXED 19NH COIL RF FIXED 128NH 80009 131 1003 00 80009 131 1003 00 80009 131 1003 00 76493 86310 1 76493 86310 1 TK1345 108 0578 00 1345 108 0578 00 TK1345 108 0707 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22506 48283 036 QUANTITY OF 2 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 8 TRANSISTOR ST TO 92 TRANSISTOR PNP SI TO 92 TRANSISTOR PNP S1 TO 92 TRANSISTOR PNP SI TO 92 TRANSISTOR PNP ST TO 92 TRANSISTOR PNP SI TO 92 TRANSISTOR
44. 19701 19701 19701 19701 19701 07716 19701 57668 57668 57668 57668 57668 57668 57668 57668 19701 57668 57668 57668 57568 57668 57668 57668 57668 57668 57668 57668 57668 57668 57568 19701 57668 Mfr Part No B6310 1 86310 1 86310 1 B6310 1 108 0543 00 108 0543 00 108 0543 00 108 0543 00 SPS8802 1 SPS8802 1 gt 151 0188 00 5 58801 5 58801 SPS8801 SPS8026 SPS8801 SPS8801 5 58803 151 1022 00 5 58801 5 58801 151 0188 00 5 58801 151 0188 00 51899 57899 5043CX10RRO0J 50430X22K00J92U SO33EDI1KO0F 5043CX22K00J92U 5033 01 00 CEAD332ROF 5043EDSKOLOF NTR25J EO9K1 NTR25J EOSK1 NTR25J E200E NTR25J E 100 252 05 1 NTR253 EO3K3 NTR25J E 2K 252 06 8 5043CX30K00J NTR2SJ EOSK1 NTR25J EO7KS NTR25J E270E NTR25J E02K2 NTR25J E270E NTR25J EO3K3 NTR25J FO03K3 NTR25J EO1K5 NTR2SJEO1KO NTR25J E 100 NTR25JEO1KO0 NTR25J EO3K3 NTR25J E 100E NTR25J E 2K 5043CX 10K00J NTR25J EO3KO REV JUL 1987 Tektronix ent No Part No 1384381 315 0303 00 A13R4382 315 0122 00 1384390 315 0301 00 A13R4391 315 0102 00 A13R4392 315 0202 00 Ai3R4394 315 0100 00 1384413 315 0332 00 13 4422 315 0153 00 1384423 315 0201 00 13 4424 315 0512 00 1384425 315 0201 00 1 31 315 0152 00 13 4432 315 0222 00 1384437 315 0103 00 1 438 315 0821 00 Al3R4441 315 0822 00 13 4442 315 0132 00 1384448 315 0271 00
45. 25W RES FILM 12K OHM 5 0 250 RES FILM 3K OHM 52 0 25W RES FILM 200 OHM 5 0 25W Mfr Code 04713 80009 04713 19701 07716 19701 19701 19701 57668 75042 57668 19701 19701 32997 19701 57668 57568 19791 57668 57568 57868 57668 00213 57668 01121 19701 57668 19701 57568 19701 19701 19701 57668 57668 19701 19701 57668 57668 57668 75042 19701 19701 57658 57668 57668 19701 57668 57668 80009 57668 57668 19701 19701 57668 57668 57668 57668 57668 Mfr Part 51899 151 0190 05 525925 5043EDGBK10F CEAD10202F 5043ED30K30F 5043 010 20 5O33ED20K50F NTR25J EO3K3 0 5621 259 05 1 5043CX10K00J 5033 5 703 3386F T04 102 5033RE27KAF NTR25J E150E NTR25J E100K 5043CX820R0J NTR25J E330E NTR25J E470E NTR25 E180E NTR25J E05K1 12405 1 5 5 NTR25J EO4K3 GB1021 5043CX120R0J NTR25J E12K0 50530X1K800J NTR25J E 20K 5043CX10K00J S033RE40K00B 5033 40 008 NTR25J E150E NTR25J E100K 5043CX820R0J 5043CX510R0J NTR25J E470E NTR25J E180E NTR25J EOSK BWH 2R200 5033 28 008 5033 12 008 NTR25J EO1K5 NTR25J E12K0 NTR25J EO3KO 5043CX8K200J NTR25J E200E NTR25J E39K0 308 0804 00 NTR25J E150E NTR25J E04K3 5033RE40K00B 5033RE12K008 NTR25J E09K4 25 01 NTR25J ET 2KO NTR25J EO3KO NTR25J E200E 7 97 Replaceable Electrical Parts 7904 Tektronix Serial Asse
46. 49 9K OHM 125 0 1254 TC TO RES FXD FILM 13K OHM 5 5 0 25W RES FXD FILM 37 4K OHM 125 0 125M TC TO RES FXO FILM 13K 5 0 25 RES FXD FILM 15 0K OHM 125 0 1254 TC TO RES FILM 75K OHM 5 5 0 25M RES FILM 75 0K OHM 125 0 125 TC TO RES FXD FILM 15 8K OHM 12 0 125W TC TO RES FXD FILM 15 9 OHM 125 0 1254 TC TO RES FXD FILM 51K OHM 5X 0 25M RES FXD FILM 49 9K OHM 175 0 1259 TC TO RES FILM 20 5K OHM 125 0 125W TC TO RES FXD FILM 21 5K 0 1 0 125 70 RES FILM 30 1K OHM 125 0 1259 TC TO RES FXD FILM 150K OHM 5 0 25W RES FXD FILM 470 OHM 5 0 25W RES FILM 30 1K OHM 1 0 125W TC TO RES FILM 1 8K OHM 5 0 25W Mfr Code Mfr Part No 57668 57668 19701 07716 19701 07716 19701 19701 19701 57668 19701 57668 19701 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 57668 19701 19701 19701 07716 19701 07716 32997 TK1450 19701 32997 5 668 5 668 19701 19701 19701 19701 19701 57668 19701 07716 07716 57668 19701 19701 07716 57668 57668 57668 57668 57668 NTR2SJ E100K NTR25J EO1K5 5043 10 002 CEAD15400F 5043CX18K00J CEAD73201F 5043CX3K600J 5043 6 2000 5043CX10K00J NTR25J E300E 5043 43 20 NTR25J EOSK1 SO043EDASK2O0F NTR253 E02K2 NTR25J EG20E NTR25J EO1K5
47. 5 0 25W MICROCKT DGTL CHANNEL SWITCH LINEAR DUAL AMPL MICROCKT LINEAR AMPLIFIER M178 MICROCKT DGTL QUAD 2 INP NOR BFR SCRN MICROCKT DGTL CHANNEL SWITCH MICROCKT LINEAR DUAL OPNL AMPL MICROCKT LINEAR AMPLIFIER M178 MICROCKT LINEAR AMPLIFIER M178 SEMICOND DVC SE ZENER PAIR SEMICOND DVC SE ZENER PAIR SEMICOND DVC SE ZENER PAIR SEMICOND DVC SE ZENER PAIR Mfr Code Mfr Part 91637 75042 24546 07716 19701 07716 19701 19701 57668 32997 57668 24546 19701 07716 75042 32997 01121 01121 75042 32997 32997 07716 07716 01121 19701 32997 91637 32997 07716 07716 01121 19701 75042 91637 75042 07716 19701 80009 04713 80009 01295 80009 04713 80009 80009 80009 80009 80009 80009 MFF1421G140ROF 0 5760 5501241 CEAD332ROF 50430 10 002 CEAD402ROF 5033 01 82 5043ED3K240F NTR25JEO1K0 3386X T07 251 CRB14 FXE 43 2 6003650 SO43EDIK210F CEAD90900F CEBTO 3011F 3386 107 501 885105 885105 0 75 00 3386X T07 500 3386X DY6 102 CEAD715ROF CEAD768ROF 882005 5043 518000 3386X T07 500 CMFS0 C180ROF 3386X DY6 102 CEAD715ROF CEAD768R0F BB2005 5043 51800 CEBTO 3160F CMF50 C180ROF CEBTO 6490F CEAD301ROF 5043CX51 R00 155 0173 05 MC1458P1 MC1458U 155 0175 05 SN74LS33NP3 155 0173 05 MC1458P1 MC1458U 155 0175 05 155 0175 05 153 0067 00 153 0067 00 153 0057 00 153 0067 0
48. 5W 73138 82PR250 37C A18R406 317 0100 00 RES CMPSN 10 OHM 5x 0 125M 01121 BB1005 A18R407 317 0100 00 RES CMPSN 10 OHM 5 0 125W 01121 81005 7 46 REV JUL 1987 Tektronix ent No Part No A18RA408 317 0100 00 A18R430 321 0233 00 A18R431 323 0141 00 8 432 321 0189 00 A18R433 321 0208 00 A18R434 321 0208 00 18 435 321 0184 00 A18R437 321 0233 00 188438 321 0172 00 188439 321 0114 00 A18R500 322 0147 00 A18R501 322 0147 00 188502 315 0122 00 4188530 321 0210 00 188531 321 0140 00 A18R532 322 0216 00 188533 322 0201 00 A18R534 321 0309 00 A18R535 321 0161 00 A18R537 321 0100 00 188541 315 0623 00 A18R543 315 0471 00 A18R544 315 0432 00 A18R600 321 0044 00 A18R801 321 0044 00 18 602 321 0299 00 A18R603 321 0306 00 A18R604 321 0306 00 Al8R605 321 0305 00 A18R630 321 0365 00 A18R631 321 0160 00 A18R632 321 0193 00 A18R633 321 0347 00 18 634 321 0318 00 188640 315 0302 00 1 41 315 0102 00 A18R642 315 0153 00 A18R643 321 0068 00 188700 315 0752 00 188701 315 0122 00 A18R702 321 0297 00 A18R703 321 0320 00 188710 323 0082 00 18 711 323 0082 00 188712 323 0119 00 A18R731 321 0289 00 18 732 321 0324 00 A18R733 315 0472 00 A18R734 315 0352 00 188735 315 0362 00 188736 311 1232 00 A18R737 311 1232 00 18 740 315 0203 00 188741 315 0204 00 188742 315 0104 00 Ai8R744 315 0224 00 A18R745 315 0102 00 A18RT303 307 0364 00 REV JUL 1987 Ser
49. 805NH COIL RF FIXED 1 75UH COIL RF FIXED 805NH COIL RF FIXED 805NH COIL RF FIXED 1 75UH RES FXD FILM 49 9 OHM 0 5 0 125W TC TO RES FXD FILM 49 9 OHM 0 5 0 125W TC TO RES FXD FILM 49 9 0 54 0 1254 TC TO RES FXD FILM 49 9 OHM 0 5 0 125W TC TO SWITCH SLIDE DPOT 0 5 125VAC SWITCH SLIDE DPOT 0 5A 125VAC Mfr Code Mfr Part No 80009 00853 52769 00853 00853 00853 00853 00853 52769 00853 00853 00853 00853 03508 03508 80009 80009 80009 80009 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 TK1345 91637 91637 91637 91637 79727 79727 670 1633 00 0155 113000 65 231 0155 820 0 0155 1840 0 0155 1840 0 0155 820 0 0155 113060 65 231 0155 820 0 0155 1840 0 0155 1840 0 D155E820F0 DA2527 1NA152 DA2527 1N4152 148 0034 00 148 0034 00 148 0034 00 148 0034 00 108 0719 00 108 0719 00 108 0718 00 108 0719 00 108 0713 00 108 0718 00 108 0719 00 108 0719 00 108 0718 00 108 0719 00 108 0719 00 108 0718 00 CMF55116649R90F CMF55116649R90F CMF55116G649R90F CMF55116649R90F GF126 0028 GF126 0028 REV JUL 1987 Tektronix nt No Part No A18 670 7922 00 A18C100 281 0775 00 A18C120 285 0683 00 A18C130 285 0686 00 18 145 283 0178 00 18 200 281 0158 00 18 201 281 0775 00 A18C202 283 0315 00 A18C203 283 0314 00 Ai8C204 283 0407 00 A18C215 281 0151 00
50. A18C220 283 0315 00 A18C221 283 0314 00 18 223 283 0407 00 180240 290 0776 00 18 241 285 0643 00 A18C245 290 0745 00 A18C246 290 0745 00 A18C333 283 0649 00 180334 281 0810 00 A18C340 283 0666 00 180341 281 0775 00 A18C400 283 0256 00 18 401 281 0158 00 A18C530 281 0775 00 18 605 290 0782 00 A18C630 281 0771 00 A18C640 281 0814 00 18 700 281 0775 00 A18C712 281 0773 00 A18C742 281 0812 00 A18CR333 152 0322 00 18 8334 152 0322 00 A18CR544 152 0141 02 18 641 152 0141 02 18 9 131 2020 00 1810 131 2022 00 1821 131 1003 00 1826 131 1003 00 A18J43 131 1003 00 181100 114 0220 00 181 135 108 0538 00 181140 108 0538 00 18141 108 0538 00 A18L200 108 0733 00 A18L201 108 0311 00 A18L220 108 0733 00 A18L221 108 0311 00 A18LR530 108 0543 00 18 80 131 0808 00 18 190 131 0608 00 A18P207 131 0608 00 180303 151 0302 00 180400 151 0302 00 REV JUL 1987 Serial Assembly No Effective Dscont Replaceable Electrical Parts 7904A Name amp Description CIRCUIT BD ASSY VERT AMP PART OF 672 1176 00 FXD CER DI 0 1UF 20 5 SOV CAP FXD PLASTIC 0 02202 5 100V CAP FXD PLASTIC O O68UF 10 100V CER 01 0 1UF 2075 100V CAP VAR DI1 7 45PF 25V FXD CER 01 0 1UF 207 50V 01 470 10 100 01 100 10 100 DI 27PF 54 50V CAP
51. CONT Performance Check Summary Part 11 Perf iei Adjustment and Characteristics ES Performance Check i Procedure Title Chec Procedure Title A and B TRIGGER SOURCE cont RIGHT Trigger source RIGHT vertical unit RIGHT trigger source button iliuminated HORIZONTAL SYSTEM Deflection Factor Compatible with all 7000 Series plug in units See Plug In Incompatibilities in Tabie 1 6 C3 Check Trigger Selector Operation 05 Check Trigger Selector Operation Does not normally require customer verification Satisfactory operation is substantiated when checked with the Signal Standardizer Calibration Fixture Gain Differences 1 or less D2 Check Horizontal Gain E4 Check Adiust Horizontal Between Horizontal And Low Frequency Linearity Gain and Low Frequency Compartments Linearity DC Linearity 0 05 division or less error at each graticule line after adjusting for no error at the second and tenth graticule lines M ABRIR e adim iue Fastest Calibrated 500 ps division D3 Check High Frequency i E6 Check Adjsut High Sweep Rate Timing Frequency Timing Horizontal Display Modes A A horizontal unit only Checked in the Operators Checkout Procedure in Section 2 ALT Duai sweep alternates between horizontal units Dual
52. Code Number to Manufacturer Also some electrical parts are selected for a value that provides optimum circuit operation These parts are identified by SEL next to the value on the schematic diagram Criteria for these SELectable parts are provided in tables adjacent to the schematic diagram on which the part is located ORDERING PARTS When ordering replacement parts from Tektronix inc inciude the following information 1 Instrument type 2 Instrument serial number 3 A description of the part if electrical include circuit number 4 Tektronix part number 4 14 SOLDERING TECHNIQUES WARNING i To avoid electric shock hazard and instrument damage disconnect the 7904A from the power source before soldering The reliability and accuracy of this instrument can be maintained only if proper soldering techniques are used when repairing or replacing parts The desoldering and removal of parts is especially critical and should be done only with an antistatic vacuum solder extractor further one approved by a Tektronix Inc Service Center Use wire solder with rosin core 6396 tin 3796 lead Contact your local Tektronix Inc representative or field office for approved solders Several circuit boards used in this instrument are multilayer Conductive paths between the top and bottom board layers may connect with one or any number of inner layers Once this inner conductive path is broken due mainly to po
53. HI at pin 6 of U2120B because of the momentary LO at pin 9 The HI at pin 6 produces a LO at pin 4 which causes pin 3 0f U2120A to go LO Because 2 is already LO pin 1 2 goes This disables the Timer stage so it operates in the Display Skip mode REV NOV 1985 Theory of Operation 7904A The Single Shot Lockout stage remains in this condition un a positive going trigger pulse is applied to pin 2 of U2120A This trigger pulse produces a LO at pin 1 of U2120A to enable U2126 and disable U2120B Now the Timer stage can operate in the normal manner for another complete frame When word 8 is completed the Channel Counter produces another end of frame pulse to again lock out the Timer stage ENCODING THE DATA Data is conveyed from the plug in units to the Readout Sys tem in the form of an analog current level code The char acters that can be selected by the encoded data are shown on the Character Selection Matrix see Fig 3 20 Each character or special function requires two currents to define it except Jump which requires only one These currents are identified as the column current and the row current corresponding to the column and row of the matrix The column and row data is encoded by programming the plug in units Figure 3 15 shows a typical encoding scheme using resistors for a voltage sensing amplifier plug in unit Notice that the 10 TS time siot pulses produced by the Time Slot Counter stage a
54. However just prior to the fourth clock pulse time both outputs are again at their level The fourth clock pulse at switches the output at pin 1 pin 8 and pin 4 after delay to the LO level to start the next cycle Notice that a Horizontal Chopped Blanking pulse is produced at pin 4 with every fifth clock pulse Also notice that with the HORIZONTAL MODE switch set to CHOP two complete cycles of the Vertical Chopping Signal are produced with each five clock pulses repetition rate two fifths clock rate and one complete cycle of the Plug In Chop Command for every five clock pulses one fifth clock rate Notice that the large shaded area produced by the Horizontal Chopped Blanking pulse see Fig 3 5 is not part of the display time crt display blanked However about the same time segment is displayed from the vertical signal source with or without Horizontal Chopped Blanking due to the change in repetition rate when in the CHOP horizontal mode The Vertical Chopping Signal at pin 1 of U4340 is connected to the Vertical Mode Logic stage see following description through LR4342 This signal is HI when the RIGHT VERT unit is to be displayed and it is LO when the LEFT VERT unit is to be displayed The Plug In Chop Command at pin 8 is connected to the plug in units in the vertical compartments through LR4344 via the Main Interface board When this signal is Hi Channel 2 of the plug in units can be displayed when this l
55. SWITCH SLIDE DPDT 0 5A 125VAC 0C TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL Mfr Code Mfr Part 19701 57668 57668 57668 57668 19701 57668 19701 57568 57668 57668 57668 57668 19701 19701 19701 57668 57668 57668 19701 19701 19791 19701 19791 19701 19701 57668 57668 57668 57668 19701 19701 19701 19701 57568 19701 19701 19701 57568 57668 57668 57668 57668 57668 57668 57668 19701 57668 19701 57668 82389 80009 80009 80009 80009 80009 80009 80009 5043CX30K00J NTR25J EO1K2 NTR25J E300E NTR2SJEOTKO NTR25 E 2K 5043CX10RR00J NTR25J EO3K3 50430X15K00J NTR25J E200E NTR25J EOSKI NTR25J E200E NTR25J EO1K5 NTR25J EO2K2 S0430X10K00J 5043CX820R0J 5043CX8K200J NTR25J EO1K3 252 270 NTR25J E03K0 5043CX820R0J 5043ED10K20F 5043ED3K570F 5043ED10K20F 5043ED3K570F 5043CX10RR00J BO33ED3K32F NTR25J E02K4 NTR25J EO5K1 NTR25J EOSK1 NTR25J E150E 5033ED3K32F 50430 10 009 S033ED1K330F 5043CX510R0J NTR25J E03K3 5033 2 00 5033 02 00 9043CX91KD0J NTR25J E200E NTR25J EO1K5 NTR2SJ E 20K NTR25J EQ7K5 NTReSJ E 100E 25 01 0 NTR25 E 20K NTR25JEO1KO 5043CX430R0J NTR25J E910E 5043CX430R0J NTR25J E 2K 11P 1137 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214
56. The LO is inverted to by U2251A and adds current to the Y vertical readout signal The X Output Amplifier consists of U2257A and 02296 It operates similarly to the Y Output Amplifier to provide the X horizontal signal to the instrument Input to the amplifier is a combination of outputs from the X Vector Generator Hori zontal Character Position Counter Decimal Position Logic and horizontal word position information from the Channel Counter The gain of this stage is fixed by the resistor val ues in the circuit SIGNALS OUT amp INTENSITY LIMITER A schematic diagram of the Signals Out amp Intensity Limiter is given on diagram 7 in Section 8 of this manual Diagrams and Circuit Board Illustrations The REV NOV 1985 Theory of 7904 schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use the stage names to further identify portions of the circuitry on diagram 7 The Signals Out circuit provides the SAWTOOTH and GATE signais to the front panel These output signals are samples of signals from the associated time base units SAWTOOTH AMPLIFIER The sawtooth signais from the and B time base units are connected to the Sawtooth Ampiifier stage through series resistors R93 and R95 respectively see Diagram 3 The front panel selector switch S1940 determi
57. The VERT TRACE SEP B control is inoperative in slaved alternate mode VERTICAL TRACE SEPARATION B Positions B trace at least 4 div above and below A trace when 7904A operates in ALT or CHOP horizontal modes See note above concerning slaved alternate VERT MODE TRIGGERING A and B TRIGGER SOURCE Selected by front panel switches Lights behind the pushbuttons are illuminated to indicate the trigger source VERT MODE The trigger source is controlled by the Vert Display Mode selection The source is shown by the illumination of the LEFT and RIGHT trigger source buttons The source follows is same as the Vert Display with the following two exceptions VERT MODE TRIGGER SOURCE CHOP LEFT 4 RIGHT for A TRIG SLAVED ALTERNATE TN LEFT for B TRIG See Vertical Display Modes under VERTICAL SYSTEM in this table for slaved alternate operation LEFT Trigger source LEFT vertical unit LEFT trigger source button illuminated RIGHT Trigger source RIGHT vertical unit RIGHT trigger source button illuminated HORIZONTAL SYSTEM Deflection Factor Compatible with all 7000 Ser es plug in units See Plug in Incompatibilities in Table 1 6 Gain Differences Between Horizontal 196 or less Compartments DC Linearity 0 05 division or less error at each graticule line after adjusting for no error at the second and tenth graticule lines Fastest Calibrated Sweep Rate 500 ps division Horizontal Display M
58. Type Used bnc to bnc connector Tektronix Part 103 0030 00 PRELIMINARY SETUP 1 Set the front panel controls as follows A INTENSITY counterclockwise FOCUS du tases midrange B INTENSITY counterclockwise READOUT 2 OFF GRAT ILLUM counterclockwise POWER 2505 TU v OFF GALIBRATORB esci pu rw 4 VERTICAL MODE LEFT A TRIGGER SOURCE VERT MODE HORIZONTAL VERT TRACE SEPARATION B midrange B TRIGGER SOURCE VERT MODE Operating instructions 7904A Connect the 7904A to a power source that meets the voltage and frequency requirements of this instrument Refer to Power Source Information and Table 1 3 Electrical Characteristics in Section 1 General Information install Tektronix 7A series amplifier units in the LEFT VERT and RIGHT VERT compartments Install Tektronix 7B series time base units in the A HORIZ and HORIZ compartments Press the POWER switch to the on locked in position Set both time base units to 1 millisecond division and triggering to auto mode with ac coupling from the internal source Rotate the A INTENSITY control until the trace is at a desirable viewing level near midrange Position the trace as necessary for an on screen display Connect the CALIBRATOR output to the input of the left amplifier unit wi
59. WH 32997 3329 048 201 4288341 321 0120 00 RES FILM 174 OHM 155 0 125W 0 07716 CEADI74R0F 288350 315 0103 00 RES FXD FILM 10K 5 0 257 19701 5043CX10K00J A28R351 321 0228 00 RES FXD FILM 2 32K OHM 19 0 1254 TC TO 19 01 5043ED2K32F A28R352 315 0300 00 RES FILM 30 OHM 53 0 25W 19701 5043 30 002 A28R352 321 0228 00 RES FXD FILM 2 32K OHM 12 0 1254 TC TO 19701 5043 02 32 A28R420 315 0181 00 RES FXD FILM 180 5 0 25 5 668 251 1 8 28 440 315 0181 00 RES FXD FILM 180 5 0 25 575668 NTR25J E180E 7 66 REV JUL 1987 Tektronix t No Part No A28R522 315 0102 00 A28R523 315 0300 00 A28R530 315 0432 00 A28R531 315 0220 00 A28R532 315 0300 00 A28R540 315 0102 00 A28R542 315 0220 00 A28R560 307 0106 00 A28R610 323 0706 01 A28R630 311 0635 00 A28R640 323 0706 01 A28R650 308 0304 00 A28R700 308 0304 00 288720 321 0066 00 A28R721 315 0102 00 A28R722 321 0205 00 A28R723 321 0264 00 A28R723 321 0262 00 A28R730 315 0911 00 A28R731 315 0822 00 A28R732 315 0751 00 A28R733 315 0332 00 A28R734 321 0275 00 A28R734 321 0276 00 A28R740 321 0205 00 A28R741 315 0102 00 288742 315 0270 00 A28R742 321 0066 00 A28R760 307 0106 00 A28R900 303 0332 00 A28R910 315 0271 00 428 911 315 0100 00 A28R920 323 0327 00 A28R921 301 0563 00 28 922 315 0201 00 A28R923 315 0150 00 A 8R924 321 0218 00 A28R930 321 0205 00 A28R940 323 0327 00 A28R941 303 0273
60. amp R inputs are both D Type Flip Flop Input Output When gated the state of the Q output changes to the state of the D input prior to the gate The outputs are complementary Gated J K Flip Flop Input Output When gated the outputs change state in response to the states at KI the inputs prior to the gate outputs are complementary When the C input is LO the amp K inputs are irrelevant m wo Gated J K Fiip Fiop with Direct Set amp Reset Inputs Input Output For devices with direct Set amp Rest inputs the indicated state at either of these inputs over rides aH other inputs J amp K inputs have no effect when S or R active signals present fhis condition will not persist when one or both S amp inputs return to their inactive level 3 5 Theory of Operation 7904A INTERCONNECTING DIAGRAM Diagram 1 shows the cable interconnections between circuit boards within the 7904A MODE SWITCH DISPLAY CONTROL AND CALIBRATOR A schematic diagram of the Mode Switch Dispiay Control and Calibrator circuits is given on diagram 2 in section 8 of this manual Diagrams and Circuit Board Illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings use the stage names to further identify portions of the circuitry on diagram 2 CALIBRATOR
61. and vice versa When the VERTICAL MODE switch is set to ALT pin 6 of the Vertical Binary stage switches the vertical display between the two vertical units However if either of the vertical plug in units are dual trace units they can be operated in the alternate mode also To provide a switching command to these units the Plug In Binary stage produces an output signal with a repetition rate that is one half the repetition rate of the signal at pin 6 of U4368 The sequence of operation when two dual trace vertical units are installed in the vertical plug in compartments and are both set for alternate operation is as follows VERTICAL MODE and HORIZONTAL MODE switches set to ALT 1 Channel 1 of LEFT VERT unit at sweep rate of B time base unit Theory of 7904 TABLE 3 9 Input Output Combinations for the Plug In Binary Stage INPUT COMMENTS ALT VERTICAL MODE VIDE SWEEP SLAVING FOR NON DELAYED CHANNEL 1 DISPLAYED ALL VERTICAL MODES EXCEPT ALT PRO CHANNEL 2 DISPLAYED DUAL SWEEP CPERATION Oo Has no effect in this case 1 output is LO prior to LO it goes and vice versa Actuated by negative going edge 2 Repetition rate one half Vertical Alternate Command rate 2 Channel 1 of RIGHT VERT unit at sweep rate of A time base unit 3 Channel 2 of LEFT VERT unit at sweep rate of B time base unit 4 Channel 2 of RIGHT VERT unit at sweep rate o
62. compatible with the horizontal deflection factor Also plug in units need not be moved from one compartment to another to change from X Y operation to other modes of operation 2 18 A X Y DISPLAY WITHOUT Z AXIS CONTROL B X Y DISPLAY WITH THE TIME BASE UNIT CONTROLLING THE Z AXIS USE THE TIME BASE LEVEL SLOPE AND TIME DIV CONTROLS TO SELECT THE PORTION OF THE DISPLAY TO BE VIEWED 4593 21 Figure 2 6 Typical X Y Displays with and without Z Axis Control RASTER DISPLAYS A raster type display can be used effectively to increase the apparent sweep length For this type of display the trace is deflected both vertically and horizontally by sawtooth signals This is accomplished in the 7904A by installing a 7B series time base unit in one of the vertical plug in compartments Normally the time base unit in the vertical compartment should be set at a slower sweep rate than the time base unit in the horizontal compartment the number of horizontal traces in the raster depends upon the ratio between the two rates Information can be displayed on the raster using several different methods In the ADD position of the VERTICAL MODE switch the signal from an amplifier unit can be algebraically added to the vertical waveform With this method the vertical signal amplitude on the crt should not exceed the distance between the horizontal lines of the raster Another method of displaying information on the raster is to use t
63. feedback capacitor C911 when a fast transition occurs The amount of differentiated signal current added to the dc signal may be adjusted by C810 to obtain best signal response OUTPUT AMPLIFIER The Output Amplifier stage consists of two current driven feedback amplifiers the right and left Output Amplifiers Because operation of the two amplifiers is identical a discussion of only the right Output Amplifier follows The input to the right Output Amplifier is at the junction of the bases of the transistor pair 0810 0820 The output of this stage is the junction of the collectors of Q910 Q920 Components R920 C911 comprise the feedback loop Signals at the bases of Q810 Q820 are amplified and inverted Low frequency signals pass 3 56 through 0910 while high frequency signals pass through Q920 Both Q910 and Q920 are common base amplifiers connected in a complimentary configuration to provide less resistive loading for driving the right horizontal crt deflection plate Zener diode VR950 located between input and output transistors of the left Output Amplifier maintains proper operating voltages within the input and output circuits Limit Center adjustment R630 provides a variable current to both left and right Output Amplifiers to more closely balance their operation Thermal sensing amplifier Q830 ensures proper current flow in R734 when ambient temperatures change It also balances out quiescent voltage level differen
64. generator to the amplifier input b Set the output of the high frequency sine wave generator and the amplifier deflection factor for eight divisions of deflection at 500 MHz Set the VERTICAL MODE switch to LEFT d CHECK crt display amplitude for 0 1 division or tess of the 500 MHz signal verifies isolation of at least 80 1 at 500 MHz e Move the amplifier to the LEFT VERT compartment without changing any settings f Set the VERTICAL MODE switch to RIGHT CHECK crt display amplitude for 0 1 division or less of the 500 MHz signal verifies isolation of at least 80 1 at 500 MHz Disconnect the high frequency sine wave generator h Set the VERTICAL MODE switch to LEFT 5 28 Connect the medium frequency sine wave generator to the amplifier input Set the medium frequency sine wave generator for eight divisions of deflection at 100 megaheriz Set the VERTICAL MODE switch to RIGHT CHECK crt display amplitude for 0 05 division or less of 100 megahertz signal verifies 100 megahertz isolation of at least 160 1 Move the amplifier to the RIGHT VERT compartment without changing any settings Set the VERTICAL MODE switch to LEFT CHECK crt display amplitude for 0 05 division or less of 100 megahertz signal verifies isolation of at least 160 1 from dc to 100 megahertz Checks and Adjustmeni 7904A Part i Performance Check 6 CHECK VERTICAL DISPLAY MODES NOTE If the preceding step was n
65. on the 7904A refer to Section 2 Operating Instructions 2 CHECK ASSOCIATED EQUIPMENT Before proceeding with troubleshooting check that the equipment used with this instrument is operating correctly Also check that the input signals are properly connected and that the interconnecting cables are not defective Check the line voltage source 3 VISUAL CHECK Visually check that portion of the instrument in which the trouble is located Many troubles can be found by visible indications such as unsoldered connections loose cable connections broken wires damaged circuit boards and damaged components 4 CHECK INSTRUMENT ADJUSTMENT Check the electrical adjustment of this instrument or of the affected circuit if the trouble appears in one circuit The apparent trouble may only be a result of maladjustment Complete adjustment instructions are given in Section 5 Checks and Adjustments 5 ISOLATE TROUBLE TO A CIRCUIT To isolate trouble to a particular circuit note the trouble symptom The symptom often identifies the circuit in which the trouble is located When trouble symptoms appear in more than one circuit check the affected circuits by taking voltage and waveform measurements Also check for the correct output signals at the front and rear panel output connectors with a test osciHoscope If the signal is correct the circuit is working correctly up to that point For example correct sawtooth output indicates that the
66. readout display f Set the time base unit for a free running not triggered sweep at a rate of 0 2 second division 0 CHECK that the readout characters are blanked out while the sweep is running and are displayed immediately after the end of the sweep each character encoded by the plug in units is displayed oniy once for each sweep h Set the READOUT GATE EXT button to EXT released i the READOUT MAN pushbutton and notice that one frame of readout is displayed j Turn POWER switch OFF Replace the fan blade re moved at start of procedure for instruments with serial number below B040000 and the side covers 5 71 Checks and Adjustment 7904A Part ll Adjustment and Performance Check G READOUT SYSTEM SN B031767 amp Above Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 1 Test Oscilloscope with 10X probes 2 Amplifier Dual Channel 17 Screwdriver slotted 4 Time Base 19 Tool Alignment G1 READOUT SYSTEM PRELIMINARY SETUP G2 ADJUST READOUT VERTICAL SEPARATION a Perform the Performance Check Power Up Sequence CENTERING AND SIZE A15R2260 A18R737 A15R2210 A28R101 A28R114 b Refer to Section 6 Instrument Options and the NOTE Change Information at the rear of this manual for any L modifications which may affect this procedure First perform step G1 then proceed G2 SETUP CONDITIONS 7904A Controis Set the 7904A c
67. signals are terminated within 0668 When the VERTICAL MODE switch is set to either ALT or CHOP the Display Right signal line switches between the LO and leveis at a rate determined by either the Chop Counter or Vertical Binary stages see Logic description diagram 4 This action displays the signal from the left vertical unit when the Display Right signal line is LO and displays the signal from the right vertical unit when the signal line is When ADD vertical mode operation is selected the Add signal line is and the Display Right Signal is LO This allows both the right and left vertical signals to pass to the output of U668 The signals from both vertical units are algebraically added and the resultant signal determines the vertical deflection The X Y Inhibit command has absolute control over the output of the Channel Switch stage Quiescently this signal is LO however when the Headout System is ready to display information on the crt this level goes blocking the signals from both vertical units When X Y inhibit is HI 1 V 0652 is turned off Current in R653 now flows through CR552 and CR654 lowering the base voltage of Q556 by one diode drop and that of Q658 by two diode drops This insures that Q558 and Q656 are turned on regardless of the state of Display Right or Add RIGHT AND LEFT CHANNEL FEEDBESIDE The operation of the Left and Right Channel Feedbeside stages are identical Therefore only a d
68. switches to inhibit the readout for any plug in unit s not selected for display When a unit is not selected the line corresponding to the opposite channel is HI to forward bias the associated diodes CR2162 and CR2163 CR2166 and CR2167 CR2170 and CR2171 or CR2174 and CR2175 The forward biased diodes cause the channel switches to bypass the encoded data from the inhibited channel However since it may be desired to display information from special purpose plug in units even though they do not produce a normal waveform display on the crt a feature is provided to over ride the channel inhibit This is done by applying a LO to the associated Force Readout input The LO level diverts the channel inhibit current and allows the data from this Theory of Operation 7904A plug in unit to reach the Column Data Switch even though it has not been selected for display by the mode switch Row Match adjustment R2183 sets the gain of the Row Data Switch to match the gain of the Row Decoder for correct output Column Match adjustment R2214 performs the same function for the Column Data Switch stage DISPLAY SKIP GENERATOR The Display Skip Generator is made up of Q2215 02223 02229 02225 This stage monitors the time multiplexed coiumn data at the output of the Column Data Switch during each time slot to determine if the information is valid data that should result in a crt display Quiescently about 100 microamperes of
69. trace separation at J43 is coupled through Q631 to the input of paraphase amplifier Q530 and Q435 Transistors Q431 and Q430 form a shunt feedback amplifier with sufficient gain to drive the inputs of U415 pins 7 and 9 When the Readout system initiates a character display it sets the X Y Inhibit logic level 1 V Emitter follower Q540 turns Q541 on The voltage on the collector of Q541 drops to zero which turns Q631 off and turns Q630 on The Aux Y Axis signal is then blocked by Q631 Y Readout signals are inverted by 0630 Readout centering is added to the composite readout signal and then applied to the input of the paraphase amplifier via Q630 At the end of the character display period X Y Inhibit returns to 0 6 V HORIZONTAL INTERFACE A schematic diagram of the Horizontal Channel Switch is given on diagram 10 in Section 8 of this manual Diagrams and Circuit Board Illustrations The schematic is divided by a gray shaded line separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use the stage names to further identify portions of the circuitry on diagram 10 The Horizontal Channel Switch circuit determines whether the signal from the output of the A horizontal or B horizontal plug in unit provides the horizontal deflection signal This circuit also accepts an input from the Readout System diagram 6 which blocks the horizontal si
70. very thin shim stock as wide as the Follower board is required to compress the contacts while the board 15 inserted into the interface connector Proceed as follows 1 Hold the Foliower board between the ends of the shim stock with the fold directly in front of the contacts With the shim stock held against the sides of the board the contacts on the sides of the board should be pressed together 2 Insert the folded end of the shim stock with the Foliower board into the rear of the interface connector through the hole in the A6 Main Interface board When the Follower board contacts are almost fully inserted into the connector hold the board in place and remove the shim stock through the front of the interface connector while fully inserting the Follower board 3 Secure the Follower board with the spring 4 Reconnect the Follower board coaxial leads to the A16 Vertical Channel Switch or A29 Horizontal interface board and the A14 Trigger Selector board 5 Replace the power supply unit 6 Replace the metal shields 4 19 7904 11 Motor Circuit Board SN 8039999 4 Below The exhaust fan and 11 Motor circuit board are removed as a unit Remove and replace the Fan assembly as follows 1 Remove one screw which holds the 11 Motor board to the standoff mount 2 Remove two screws which fasten the fan motor assembly to the mounting bracket 3 Disconnect the pin
71. 0 25W 19701 5043CX10RROOJ A28R101 311 0605 00 RES VAR NONW 200 OHM 0 54 32997 3329H G48 201 288110 321 0251 00 RES FXD FILM 4 02K 0HM 1 0 125W TC TO 19701 5033 04 020 288111 321 0193 00 RES FILM 1K OHM 12 0 125W TC TO 19701 5033ED1KO0F A28R112 321 0078 00 RES FXD F1LM 63 4 12 0 1250 TC TO 91537 CMF55116G63RA0F A28R113 315 0822 00 RES FILM 8 2K 5 0 25 19701 5043CX8K200J 288114 311 0607 00 RES VAR TRMR LOK OHM 0 SW 73138 82 25 2 A28R120 323 0167 00 RES FXD F1LM 536 13 0 50 TC TO 07716 536 A28Ri21 311 0609 00 RES VAR 2K OHM 0 SW 32997 3329 158 202 A28R1 2 321 0135 00 RES FXD FILM 249 OHM 1 0 125wW TC TO 07716 CEAD 249ROF A28R123 315 0822 00 RES FXO FILM 8 2K OHM 52 0 25W 19701 5043 8 2002 A28R130 315 0563 00 RES FXO FILM 58K OHM 5 0 25W 19701 50430X56K00J A28R131 321 0135 00 RES FILM 249 OHM 13 0 125W TC TO 07716 0249 0 A28R132 323 0167 00 RES FILM 536 OHM 125 0 5W TC T0 07716 CECDS36ROF A28R133 321 0078 00 RES FILM 63 4 OHM 12 0 1254 0 91637 CMF55118G63R40F A28R140 315 0822 00 RES FXD FILM 8 2K 5 0 25 19701 5043CX8K200J 28 141 321 0193 00 RES FILM 1K OHM 135 0 125W TC TO 19701 5033 01 00 288142 315 0222 00 RES FXD FILM 2 2K OHM 5 0 258 57668 NTR25J FO2K2 A28R150 307 0106 00 RES FXD CM
72. 0 39 TRANSISTOR PNP SI TO 18 RES FILM 10 0K OHM 1 0 125W TC TO RES FXD FILM 10 0K OHM 1 0 125w TC TO RES FXD FILM 30 1K OHM 1 0 125W TC TO RES FXD FIUM 30 1K OHM 1 0 125W TC TO RES FXD FILM 200K OHM 1 0 125W TC TO RES VAR 200K OHM 0 SW RES FXD FILM 20 0K OHM 1 0 125W TC TO RES FXD FILM 100K 1 0 1254 0 RES VAR NONWW LOOK OHM 0 5W RES FXO FILM 16 2K OHM 1 0 125W TC T0 RES FXD FILM 100K OHM 1 0 1259 TC TO RES VAR 50K OHM 0 Sw RES FILM 8 25K OHM 1 0 125W TC TO RES FXD FILM 51 1K OHM 1 0 125W TC TO 80009 04222 04222 56289 56289 00853 00853 19396 80031 04222 54473 54473 54473 04222 04222 56289 56289 00853 00853 19396 80031 04222 04222 04222 54473 03508 03508 03508 76493 76493 76493 22526 04713 04713 04713 04713 04713 04713 04713 04713 04713 04713 04713 19701 19701 57668 57668 07716 32997 19701 19701 32997 19701 19701 32997 19701 07716 670 4768 20 MA101A100KAA MA2OSE104MAA 192P27352M447 192P47252R468 0151 89160 0155 1050 0 004908103 2807000222MJ02 MA205E104MAA ECE A25V22L ECE A25V22L ECE A25V22L MALOLALOOKAA 205 104 192P27352M447 192P47252R468 D151F891G0 D155F1050F0 004908103 2807 00222 202 MA205E104MAA 205 104 MA101C471KAA ECE A6V47L DA2527 1N4152 DA2527 1N4152
73. 0 5 ns 500 ps is the fastest calibrated sweep rate for the 7904A If the given limits are met omit the remainder of this step Set the time base Time Div to 2 ns Set the time mark generator for a 2 ns sine wave timing signal EXAMINE sine wave display alignment of the second and tenth sine wave peaks at the second and tenth graticule line 5 58 peaks with the second and tenth graticule lines NOTE It is important that the adjustment of C810 and C850 be balanced Therefore each capacitor should be adjusted equally Set the time base Time Div to 5 ns and the Mag control to X10 time base sweep rate of 0 5 nanoseconds division Set the time mark generator for 1 ns sine wave timing signals Set the amplifier deflection factor for approximately four divisions of amplitude EXAMINE the sine wave display for four cycles over the center eight divisions sine wave peaks at the second and tenth graticule lines ADJUST HF Timing adjustments C310 and C340 on the A28 Horizontal Board for four cycles of sine wave signal over the center eight graticule divisions NOTE it is important that the adjustment of C310 and C340 be balanced Therefore each capacitor should be adjusted equally EXAMINE crt display for one sine wave cycle for each two graticule divisions over the center eight divisions of display ADJUST HF Linearity adjustments 8312 and R340 the A28 Horizontal Amplifier Board for one sine wav
74. 00 RES VAR NONWW 200K 0HM O 5W 32997 3386F T04 204 A18R300 322 0133 00 RES FILM 237 1 0 258 TC TO 75042 CEBTO 2370F A18R304 317 0100 00 RES CMPSN 10 OHM 5x 0 125W 01121 B81005 188310 321 0164 00 RES FXD FILM 499 OHM 1 0 125W TC T0 19701 5033ED499ROF 188311 321 0239 00 RES FILM 3 01K OHM 175 0 125W TC TO 19701 5043 3 010 188312 323 0115 00 RES FXD FILM 154 OHM 12 0 5W TC TO 91637 MFF1226G154ROF A18R320 321 0164 00 RES FILM 499 19 0 1258 0 19701 5033ED499ROF 188321 321 0193 00 RES FXD FILM 3K OHM 126 0 125W TC TO 19701 5033EDIKOOF A18R330 321 0354 00 RES FXO FILM 47 5 OHM 125 0 1259 TC TO 19701 5043ED47K50F A18R331 321 0342 00 RES FXD FILM 35 7K OHM 125 0 1254 TC T0 07716 CEAD35701F A18R332 321 0357 00 RES FXD FILM 51 1K OHM 12 0 125W TC TO 07716 51101 A18R333 321 0339 00 RES FXD FILM 33 2K OHM 15 0 125W TC TO 07716 CEAD33201F A18R334 321 0239 00 RES FILM 3 01K OHM 15 0 1250 TC T0 19701 5043 03 010 A18R335 311 1214 00 RES VAR 200K OHM 0 5W 32997 3386F T04 204 A18R336 321 0193 00 RES FXD FILM IK OHM 12 0 125W TC TO 19701 5033 01 00 Ai8R400 321 0123 00 RES FXD FILM 187 OHM 1 0 125W 0 07716 CEADI87ROF AL8R404 311 1266 00 RES VAR NONW 2 5K OMM 0 5W 32997 3329P L58 252 188405 311 0978 00 RES VAR NONW 250 0
75. 0188 00 A1304488 151 0192 00 A1304492 151 0188 00 1304494 151 0302 00 1304498 151 0302 00 A13R4302 815 0100 00 A13R4304 315 0223 00 1384305 321 0193 00 81384306 315 0223 00 1384307 321 0193 00 1384312 321 0147 00 1384313 321 0239 00 A13R4314 315 0912 00 1384315 315 0512 00 13 4316 315 0201 00 13 4318 315 0101 00 1384319 315 0512 00 A13R4321 315 0332 00 1384322 315 0202 00 1384333 315 0682 00 1384334 315 0303 00 A13R4335 315 0512 00 A13R4336 315 0752 00 A13R4342 315 0271 00 A13R4343 315 0222 00 A13RA344 315 0271 00 A13RA345 315 0332 00 A13R4354 315 0332 00 1384356 315 0152 00 1384357 315 0102 00 1384358 315 0101 00 A13R4363 315 0102 00 A13R4386 315 0332 00 1384367 315 0101 00 1384359 315 0202 00 A13R4374 315 0103 00 A13R4380 315 0302 00 7 26 Serial Assembly No Effective _ Dscont Name amp Description CHOKE RF FIXED 3 9UH CHOKE RF FIXED 3 9UH CHOKE RF FIXED 3 9UH CHOKE RF FIXED 3 9UH COIL RF FIXED 1 109 COIL RF FIXED 1 109 COIL RF FIXED 1 1UH COIL RF FIXED 1 1UH TRANSISTOR SELECTED TRANSISTOR SELECTED TRANSISTOR PNP SI 70 92 TRANSISTOR SELECTED TRANSISTOR SELECTED TRANSISTOR SELECTED TRANSISTOR NPN S1 TO 92 TRANSISTOR SELECTED TRANSISTOR SELECTED TRANSISTOR PNP SI TO 92 TRANSISTOR N CHAN 51 T0 18 TRANSISTOR SELECTED TRANSISTOR SELECTED TRANSISTOR PNP ST TO 92 TRANSISTOR SELECTED TRANSISTOR PNP SI T
76. 0573 00 214 0579 00 214 0579 00 7 27 Replaceable Electrical Parts 7904 Tektronix Serial Assenbly No Mfr Component No Part No Effective Dscont Name amp Description Code Mfr Part No A13TP4468 214 0579 00 TERM TEST POINT BRS CD PL 80008 214 0579 00 A13TP4470 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A13TP4471 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 1304320 155 0011 00 MICROCKT DGTL CLOCK amp CHOP BLANKING 80009 155 0011 00 A13U4340 155 0010 00 MICROCKT DGTL CHOP COUNTER 80009 155 0010 00 A13U4358 155 0013 00 MICROCKT DGTL DC BINARY 80009 155 0013 00 A13U4368 155 0013 00 MICROCKT DGTL DC BINARY 80009 155 0013 00 A13U4412 155 0013 00 MICROCKT DGTL DC BINARY 80009 155 0013 00 A13U4428 155 0009 00 MICROCKT DGTL HORIZ LOCKOUT LGC 80009 155 0009 00 A13U4485 155 0012 00 M CROCKT DGTL Z AXIS AMPLIFIER 80008 155 0012 00 13 84334 152 0166 00 SEMICOND DVC DI ZEN SI 86 2V 52 0 4W DO 7 04713 SZ11738RL 7 28 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr Component No Part No Effective _ Dscont Name amp Description Code X Mfr Part No Al4 670 4776 20 CIRCUIT BD ASSY TRIGGER SELECT 80009 870 4776 20 A14C237 283 0221 00 CAP FXD CER D1 0 47UF 20 50V 04222 3430 050C 474M A14C240 290 0183 00 CAP ELCTLT 1UF 10 35V 05397 T3228105K035AS 14 250 290 0525 00 CAP ELCTLT 4 7UF 2025 50V 05397 7368 475 050 5 A14C270 283 0
77. 1000 10 1009 04222 101 102 A1C1919 281 0773 00 CAP D1 0 01UF 10 100V 04222 201 10 1 1920 281 0773 00 D1 0 01UF 10 100V 04222 201 103 1 1921 281 0813 00 DI 0 047UF 2075 50V 05397 412 473 5 2 1 1935 281 0797 00 010100 042057 CER 01 15 10 100 04222 106 150 1 1935 081 0759 00 8042058 CAP FXD CER 01 22 105 100V 04222 MA101A220KAA A1C1938 281 0812 00 CER 01 1000PF 10 100V 0422 101 102 1 1950 281 0775 00 01 0 20 50 04222 205 104 A1C1952 281 0786 00 CAP 01 150 10 100 04202 101 151 A1C1953 281 0775 00 CAP CER 01 0 iUF 2025 50V 04222 205 104 A1C1955 290 0804 00 CAP ELCTLT 10UF 50 10 25V 55680 ULBIEIOOTAAANA A1C1956 290 0745 00 CAP ELCTLT 22UF 50 10 25V 54473 ECE A25V221 1 1994 281 0775 00 CAP 01 0 10 20 50 04222 MA205EI04MAA A1C1995 290 0804 00 CAP FXD ELCTLT 10UF 450 104 25V 55680 ULBIELOOTAAANA A1C1997 290 0804 00 CAP FXD ELCTLT 10UF 450 10 25V 55680 ULBIELOOTAAANA ATCR1900 152 0141 02 SEMICOND DVC 01 SW SI 30V 150MA 30V DO 35 03508 DA2527 1N4152 ATCR1902 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 1 4152 1 81916 152 0322 00 SEMICOND DVC DI SCHOTTK
78. 11 3K 1 0 125 1 170 19701 5043ED11K30F A15A1R2268 321 0295 00 8021190 B029999 RES FILM 11 5K OHM 1 0 125W TC TO 07716 11501 15 182268 321 0296 00 021190 8029999 RES FILM 11 8K OHM 126 0 1258 TC TO 07718 11801 5 18 2268 321 0298 00 8021190 029999 RES FILM 12 4K OHM 175 0 125W TCSTO 07718 CEAD12401F A15A1R2268 321 0299 00 8021190 029999 RES FILM 12 7 OHM 15 0 1250 TC TO 19701 5033 012 7 0 15 182268 321 0631 00 8021190 8029999 RES FILM 12 5K OHM 1 0 1258 0 91637 MFF1816612501F A15A1R2268 321 0367 00 8030000 RES FILM 64 9K 0 1 0 125 10 07718 CEAD64901F R2268 15 SELECTABLE 15 1 2269 321 0331 00 8030000 RES FXD FILM 27 4K 1 0 125 10 19701 5043 27 40 15 162271 315 0183 00 8030000 RES FILM 18K 5 0 25 19701 5043CX18K00J AL5A1R2273 311 1226 00 8010100 8029999 RES VAR 2 5K OHM 0 5W 32997 3386 04 252 A15A1R2274 321 0153 00 8010100 029999 RES FILM 383 OHM 1 0 1259 TC TO 07718 15 162275 321 0170 00 8010100 8029999 RES FILM 576 OHM 126 0 125W TC TO 07716 CEADS76ROF Al5AIR2276 315 0223 00 8010100 8029999 RES FILM 22K OHM 5 0 25W 19701 5043CX22K00J92U A15A1R2276 321 0251 00 8030000 RES FXD FILM 4 02K OHM 1 0 125W TC T0 19701 5033ED4KO020F A15A1R2277 321 0250
79. 18181 315 0334 00 12 18182 315 0754 00 12 1 214 0579 00 12 17 126 214 0579 00 A12A1U75 155 0067 02 A12A1U179 156 0481 02 Ai2A1VR52 152 0590 00 ALZALVR72 152 0243 00 ALZALVR88 152 0212 00 7 24 Serial Assembly Effective Dscont 8010100 8031833 8010100 8010100 8031832 8031832 8031832 Name amp Description RES FXD FILM 150K OHM 5 5 0 25W RES FXD FILM 56 OHM 5 0 25M RES FXD FILM 56 OHM 55 0 25M RES FXD FTLM 39 2K OHM 15 0 125W TC TO RES FXD FILM 470 OHM 5 5 0 25M RES FXD FILM 29 4K OHM 12 0 125W TC TO RES FXD FILM 34 0K OHM 17 0 125 TC TO RES FILM 1K OHM 125 0 1254 TC TO RES FILM 11 0 OHM 12 0 1254 TC TO RES FILM 8 87K OHM 125 0 1259 TC T0 RES FILM 8 66K OHM 12 0 125W TC TO RES FXD FILM 1 2K OHM 5 6 0 25W RES FXD FILM 2 7K 5 0 254 RES FXD FILM IM OHM 525 0 25W RES VAR TRMR 2 5K OHM 0 50 RES VAR NONW 2K OHM 20 0 SW RES FXD FILM 20K OHM 52 0 25M RES FXD FILM 226K OHM 125 0 125W TC TO RES FXD FILM 15 OHM 55 0 25W RES FILM 100 OHM 5 5 0 25W RES FXO FILM 390 0HM 54 0 5W RES FXD FILM 47K OHM 5 0 25W RES FILM 4 7K OHM 5 0 25W RES FXD FILM 10 OHM 54 0 25M RES FXD FILM 270K OHM 5 6 0 25W RES FXD FILM 470K OHM 5 5 0 25W RES FXD FILM 2 7K OHM 5 5 0 25W RES FXO FILM
80. 1987 7 19 Replaceable Electrical Parts 7904A Tektronix nt No Part No Ali 670 4641 00 11820 147 0035 00 290 0778 00 AliCi3 290 0768 00 ALICRIO 152 0141 02 11 13 152 0141 02 ALICR21 152 0141 02 ALICR22 152 0141 02 ALICR23 152 0141 02 ALICR24 152 0141 02 11 80 131 0608 00 11010 151 0301 00 11020 156 0281 00 ALIRIO 301 0271 00 315 0470 00 ALIRI3 301 0271 00 11 20 307 0059 00 AllR24 321 0201 00 ALIR25 321 0239 00 11627 321 0022 00 20 Serial Assembly No Effective Dscont Name amp Description CIRCUIT BD ASSY FAN MOTOR DC BRUSHLESS 3000 RPM 10 15V CAP ELCTLT 1UF 50 10 50V NPLZD CAP ELCTLT 10UF 450 1076 100V0C SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 SEMICOND DVC DI SW 51 30V 150MA 30V 00 35 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 2 TRANSISTOR PNP ST TO 18 MICROCKT LINEAR 4 XSTR HIGH CUR ARRAY RES FXD F1LM 270 OHM 55 0 5M RES FXD FILM 47 OHM 55 0 25M RES FILM 270 OHM 5 0 5W RES FXD CMPSN 6 2 5 0 5 RES FXD FILM 1 21K OHM 12 0 1258 TC TO RES FXD FILM 3 01K 12 0 125W TC TO RES FXO FILM 16 5 OHM 176 0 1254 TC TO Mfr Code 80009 25088 54473 54473 03508 93508 03508 0
81. 27 OHM 54 0 25W 19701 5043CX27R00J A23R45 315 0182 00 RES FILM 1 8K OHM 55 0 25W 57668 252 8 A23R46 315 0123 00 RES FILM 12K OHM 5 0 25W 57668 NTR25J E12K0 A23R47 301 0184 00 RES FILM 180K OHM 5 0 5W 57668 TR50J E180K A23RT9 307 0353 00 RES THERMAL 5 OHM 10 15454 5DASROK270SS SIL A23RT13 307 0353 00 RES THERMAL 5 OHM 10 15454 5DA5ROK270SS SIL A23T8 120 0636 00 XFMR PWR STPDN LINE TRIGGER TK2038 120 0636 00 A23125 120 0743 00 XFMR TOROID 80009 120 0743 00 A23130 120 0744 00 XFMR TOROID 5 WINDINGS TK1345 120 0744 00 A23135 120 0747 00 XFMR TOROID TK1345 120 0747 00 23 31 214 0579 00 8010100 8042116 TERM TEST POINT BRS CD PL 80009 214 0579 00 A23TP34 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A23TP38 214 0579 00 8 010100 8042116 TERM TEST POINT BRS CD PL 80009 214 0579 00 A23TP46 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A23VR38 152 0241 00 SEMICOND DVC DI ZEN SI 33V 54 0 4M DO 7 14552 1N9738 A23VR45 152 0428 00 SEMICOND DVC DI ZEN S1 120V 5 0 4W 00 7 04713 5713202 189878 A23W5 131 0566 00 8020000 BUS CONDUCTOR DUMMY RES 0 094 00 X 0 2251 24546 OMA 07 7 60 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr t No Part No Effective _ Dscont Name amp Description Code Mfr Part No A24 119 1048 00 DELAY LINE ELEC 65NS 50 OHMS 80009 119 1048 00 NO ELECTRICAL PARTS 4059 7 NOT
82. 365 L X 0 025 BRZ GLD PL QUANTITY OF 2 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 7 TRANSISTOR NPN SI TO 18 TRANSISTOR NPN SI TO 18 Mfr Code Mfr Part No 80009 04222 19396 19396 05397 59660 04222 04222 04222 04222 59660 04222 04222 04222 55680 56289 54473 54473 00853 04222 00853 04222 51642 59660 04222 55680 04222 04222 04222 04222 04222 50434 50434 03508 03508 80009 80009 80009 80009 80009 80009 76493 76493 76493 80009 TK1345 80008 TK1345 TK1345 22526 22526 22526 04713 04713 670 7922 00 MA205E104MAA 223J01PT485 583 01 605 C330C10471U1CA 518 006 G 7 45 205 104 10051A47 1KA2065 08051A101KA2075 ULA105A270J8 518 000 A 1 0 3 10051A471KA2065 08051A101KA2075 ULA105A270J8 ULATA220TAA 192P47252R468 ECE A25V22L 25 221 0155 1050 0 101 5 D151F89160 205 104 200100N1500131J 518 006 G 7 45 MA205E104MAA ULBIV4R7TAAANA MALOGE222MAA MA101A101KAA MA205E104MAA MA201C103KAA 101 102 5082 2672 5082 2672 042527 144152 042527 144152 131 2020 00 131 2022 00 131 1003 00 131 1003 00 131 1003 00 114 0220 00 JWM B7059 JWMEFB7 059 JWM B7059 108 0733 00 108 0311 00 108 0733 00 108 0311 00 108 0543 00 48283 036 48283 036 48283 036 51899 51899 7 45 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr t No Part Ef
83. 48283 036 QUANTITY OF 2 A5P309 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 10 5 310 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 4 A5P318 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 5 50342 151 0302 00 TRANSISTOR NPN 51 T0 18 04713 51899 50346 151 0302 00 TRANSISTOR NPN SI TO 18 04713 57899 50362 151 0302 00 TRANSISTOR NPN SI 10 18 04713 ST899 A50366 151 0302 00 TRANSISTOR NPN 51 TO 18 04713 51899 50376 151 0192 00 TRANSISTOR SELECTED 04713 5 58801 A5Q382 151 0192 00 TRANSISTOR SELECTED 04713 5 58801 50384 151 0342 00 TRANSISTOR 51 10 92 07263 5035928 A5R324 315 0152 00 RES FILM 1 5K OHM 5 0 25W 5 668 NTR25J EQ1K5 A5R325 311 1373 00 RES VAR PNL 5K OHM 1W 32997 81 1 20 0344 A5R325 315 0152 00 RES FILM 1 5K OHM 54 0 25W 57668 NTR25J EO1KS A5R341 307 0109 00 RES CMPSN 8 2 5 0 25 80008 307 0109 00 A5R342 315 0202 00 RES FXD FILM 2K OHM 55 0 25W 57668 NTR25J E 2K A5R343 315 0162 00 RES FXO FILM 1 6 OHM 5 0 25W 19701 5043 1 600 A5R345 307 0109 00 RES CMPSN 8 2 OHM 5 0 25W 80009 307 0109 00 A5R346 315 0202 00 RES FILM 2K OHM 55 0 25W 57668 NTR25J E 2K A5R347 307 0109 00 RES CMPSN 8 2 OHM 5 0 25W 80000 307 0109 00 A5R361 307 0109 00 RES FXD CMPSN 8 2 OHM 54 0 25W 80009 307 0109
84. 50 OHM 125 0 05 TC TO 91837 CMF50 F50ROOF Al4R414 325 0053 00 RES FILM 50 OHM 12 0 05W TC TO 91637 CMF50 F50R00F 148416 325 0053 00 RES FXD FILM 50 OHM 125 0 050 TC TO 916537 CMF50 F50R00F 148417 325 0053 00 RES FXD FILM 50 OHM 125 0 05V TC TO 91537 CMF50 F50RO0F 148418 325 0053 00 RES FXD F1LM 50 OHM 125 0 05M TC T0 91637 50 5 148419 321 0143 00 RES FXD FILM 301 1 0 1258 0 07716 148420 321 0126 00 RES FXD FILM 200 OHM 1 0 1250 TC TO 19701 5033 020080 148425 321 0143 00 RES FXD FILM 301 0HM 12 0 125W TC TO 07716 CEAD3OIROF 148426 321 0126 00 RES FXD F1LM 200 OHM 12 0 125W 0 19701 5033 020080 A14R432 321 0202 00 RES FILM 1 24 OHM 126 0 125W TC TO 24546 5501241 148433 322 0111 00 RES FILM 140 OHM 1X 0 25W TC TO 91637 MFF14216140ROF Al4R434 322 0170 00 RES FXD FILM 575 OHM 13 0 25W TC TO 75042 5780 148435 321 0202 00 RES FXD FILM 1 24K OMM 155 0 125 TC TO 24546 NA5501241F A14R436 321 0147 00 RES FILM 332 OHM 1 0 125W TC 70 07716 2 148437 315 0103 00 RES FXD FILM 10K OHM 5 0 25W 19701 5043CX10K00d 14R438 321 0155 00 RES FILM 402 OHM 12 0 125W TC TO 07716 CEADAO2ROF A14R439 322 0114 00 RES FXD FILM 150 OHM 13 0 254 TCaTO 75042 1500 148440 317 0200 00 RES FXD CMPSN 20 5 0 125 01121 82005 1
85. 52 0 5M 00 7 04713 575064681 A22VR17 152 0283 00 SEMICOND DVC D1 ZEN SI 43V 55 0 4W 0 07 04713 Z14257KRL AZ2VR32 152 0281 00 SEMICOND DVC DI ZEN S1 22V 5 0 4W DO 7 12954 1N9698 D0 35 A 2NR36 152 0281 00 SEMICOND DVC DI ZEN S1 22V 55 0 4M DO 7 12954 1N969B D0 35 A22VR47 152 0283 00 SEMICOND DVC DT ZEN SI 43V 55 0 4W D 07 04713 Z14257KRL A22VR152 152 0175 01 SEMICOND DVC DI ZEN SI 5 6V 52 0 4W D0 7 04713 579502181 A22VR156 152 0175 01 SEMICOND DVC Di ZEN SI 5 6V 5x 0 4M DO 7 04713 570500151 7 58 REV JUL 1987 Tektronix t No Part No 23 670 6259 01 A23 870 6259 02 A23C5 283 0022 00 A23C5 119 1168 00 A23C6 283 0022 00 A23C19 283 0057 00 A23C27 283 0280 00 A23C27 283 0351 00 A23C28 283 0280 00 23 28 283 0351 00 A23C29 285 0939 00 23 31 290 0891 00 23 35 283 0060 00 23 36 283 0280 00 A23C38 283 0279 00 A23C39 290 0891 00 A23C42 283 0079 00 A23C43 290 0767 00 A23CRi5 152 0396 01 A23CR15 152 0750 00 A23CR32 152 0107 00 A23CR33 152 0400 00 A23CR34 152 0400 00 23 836 152 0061 00 A23CR37 152 0061 00 A23CR38 152 0107 00 23 839 152 0400 00 A23CR40 152 0107 00 2 152 0400 00 A23CR S 152 0061 00 A23CR46 152 0581 00 A23CR49 152 0107 00 230519 150 0035 00 23 8 119 0181 00 A23E13 119 0181 00 A23L24 108 0681 00 23030 151 0508 00 23034 151 0632 00 23040 151 0632 00 A23Q43 151 0347 00 A23045 151 0350 00 23046 151 0260 00 A23R5 304 0270 00 A23R8 308 0503 00 A23R9 304 0473 0
86. 57668 NTR253 E150K 15 182207 321 0405 00 030000 RES FILM 162K OHM 1 0 1258 TC TO 07716 16202 A15A1R2208 321 0335 00 8010100 8029999 RES FILM 30 1K OHM 125 0 1254 TC T0 57668 AL5A1R2208 321 0434 00 8030000 RES FILM 324K OHM 126 0 1254 TC TO 07716 CEAD32402F AL5A1R2209 321 0335 00 8010100 B029999 RES F1LM 30 1K 0HM 12 0 1254 TC TO 57668 RBIAFXESOKI 15 162210 311 2232 00 8030000 RES VAR TRMR 2K 205 0 50 LINEAR 50 GFO6UT 2K A15AIR2211 315 0752 00 8010100 B029999 RES FILM 7 5K OHM 555 0 25W 57668 1 254 07 5 ALSAIR2211 315 0332 00 8030000 RES FILM 3 3K OHM 5 0 25W 57668 25 03 3 15 182212 321 0218 00 8030000 RES FILM 1 82K OMM 175 0 1254 TC T0 19701 5033 8 15 182213 321 0259 00 010100 8029999 RES FILM 4 87K OHM 15 0 1250 TC T0 07716 048700 A15A1R2213 321 0221 00 8030000 RES FXD FILM 1 96K OHM 125 0 125W TC TO 19701 5043EDIK960F AL5A1R2214 311 1224 00 8 010100 8029999 RES VAR NONW 500 OHM 0 5W 32997 3386 04 501 15 1 2215 315 0133 00 8010100 80299299 RES FILM 13K 5 0 25 19701 5043 13 002 15 152216 321 0452 00 8030000 RES FILM 499K OHM 1 0 125W TC 70 19701 5043 0499 0 ALSAIR2217 315 0124 00 8010100 8029998 RES FILM 120K OHM 525 0 25W 19701 5043 120 02 1
87. 6 Unsoider the 3 power transformer leads from the A23 Power Supply inverter board Remove the excess solder from the board pads with a vacuum type antistatic desoldering tool 7 Remove the 2 screws connecting the transformer mounting chassis to the power supply rear heatsink 8 Remove the 5 securing screws from the A12 Control Rectifier board 9 Lift the circuit board and attached power transformer from the power supply unit 10 To repiace the A12 Control Rectifier board reverse the order of removal Match the index arrow on the pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown on the circuit board illustrations in Section 8 Diagrams and Circuit Board Hiustrations A23 Power Supply Inverter Circult Board An exploded view drawing of the power supply unit is given in Section 9 Replaceable Mechanical Parts at the 4 22 rear of this manual Remove and replace the A23 Power Supply Inverter board as follows WARNING The power supply unit has been tested at the factory to ensure safe operation Improper repair of this unit can result in hazardous potentials on the instrument chassis Do not remove the plate insulator block insulator or transistor shield from the heatsink See the exploded view drawing of the power supply unit for the location of the components 1 Slide the power supply unit out of the instrument see Power Supply Unit Removal 2 Remov
88. 76 CONTACT CONN RCPT ELEC CKT 0 38 76 CONTACT CONN RCPT ELEC CKT BD MT 3 PRONG CONN ELEC CKT BD MT 3 PRONG CONN RCPT ELEC CKT BD MT 3 PRONG CONN RCPT ELEC CKT CONN RCPT ELEC CKT CONN REPT ELEC CKT CONN RCPT ELEC CONN RCPT ELEC CKT B CONN RCPT ELEC CKT 3 PRONG 3 PRONG 3 PRONG 3 3 3 C UJ 333334 8 PRONG PRONG PRONG 0 0 0 D 0 D t CONN RCPT ELEC CKT BD MT 3 PRONG TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 5 TERMINAL PIN 0 365 L X 0 025 BRZ GLB PL QUANTITY OF 7 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 10 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 8 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 5 Mfr Code _ Mfr Part No 80009 670 4775 00 80009 670 4775 01 80009 670 4775 02 94473 25 1001 55680 TLBIE2 1TCAANA 84411 270 10391 54473 84411 00853 55680 00853 55680 ECE B25V100L 270 10391 5560 10071008 2 220 566001 00T100B 2 200 54473 52763 05397 0
89. 7904A Controls GATE A or B Switch Test Oscilloscope o e o E Coaxial Test Equipment Controls Test Oscilloscope Vertical Deflection Factor 2 V div Sweep Rate 0 2 ms div Time Base Triggering Auto AC Internat Sweep Rate 0 1 ms div 4593 516 CHECK the test oscilloscope display for a gate waveform 5 divisions in amplitude within 10 and a baseline at zero volts within one volt Move the time base unit to the HORIZ compartment Set the GATE selector switch to the B position CHECK the test oscilloscope display for a gate waveform 5 divisions in amplitude within 10 and a baseline at zero volts within one volt C7 CHECK GRATICULE ILLUMINATION OPERATION NOTE If the preceding step was not performed first perform step C1 then proceed C7 SETUP CONDITIONS 7904A Controls GRAT ILLUM GATE or EXT Switch GATE A or B Switch HORIZONTAL MODE kod a Test Equipment Controls Time Base Swoop Hale iliac RR og 0 2 s div Triggering Auto AC Internal 4593 517 Checks and Adjustment 7904A Part ii Adjustment and Performance Check CHECK that rotating the GRAT ILLUM control throughout its range varies the illumination of the graticule Set the GRAT ILLUM control fully clockwise to the PULSED detent position Set the A INTENSITY control for a visibl
90. 8620 04 570 4769 20 670 1633 00 670 7922 00 670 1634 00 670 5841 20 670 5841 21 670 5834 20 670 5834 21 670 5960 03 670 5960 04 670 6259 01 670 6259 02 119 1048 00 670 8052 00 670 8053 00 670 4346 00 670 1632 05 670 1632 06 REV JUL 1987 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr Component No Part No Effective _ Dscont Name amp Description Code Mfr Part No A29 670 8059 00 CIRCUIT BD ASSY HORIZONTAL INTERCONNECT 80009 670 8059 00 A30 570 0702 06 CIRCUIT BD ASSY GRATICULE LAMPS 80009 670 0702 06 1 670 8046 00 CIRCUIT BD ASSY FLEX CON 80000 670 8046 00 PART 672 1176 00 NO ELEC PARTS REV JUL 1987 7 5 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr nt No Part No Effective Dscont Name amp Description Code Mfr Part No 570 8080 00 8 010100 8042057 CIRCUIT BD ASSY FRONT PANEL 80009 670 8060 00 570 8060 01 042058 CIRCUIT BD ASSY FRONT PANEL 80009 670 8060 01 A1Ci901 281 0773 00 CAP DI 0 01UF 10 100V 04222 201 103 A1Ci904 281 0812 00 CER DI 1000 10 1007 04222 101 102 1 1905 281 0812 00 CAP FXD CER 01 1000 10 1009 04222 101 102 A1C1908 290 0187 00 CAP ELCTLT 4 782 205 35V 05397 108475 035 5 A1C1914 281 0763 00 DI 47PF 1025 100V 04222 101 470 1 1918 281 0812 00 CAP CER 01
91. A Diagram of clock generator stage B idealized waveforms for clock generator stage R4313 R4314 and its duty cycle is determined by the ratio of 4312 and R4313 to R4314 The pulse train at pin 14 is connected to pin 16 through C4315 Capacitor C4315 along with the internal resistance of U4320 differentiates the pulse train at pin 14 to produce a narrow negative going pulse coincident with the falling edge of the pulse train positive going pulse coincident with rising edge has no effect on circuit operation This negative going pulse is connected to 15 through an inverter shaper circuit that is also part of U4320 The output at pin 15 is a positive going clock pulse with a repetition rate of about two megahertz The Vertical Chopped Blanking stage is made up of the remainder of U4320 This stage determines if Vertical Chopped Blanking pulses are required based upon the operating mode of the vertical system or the plug in units dual trace units only Vertical Chopped Blanking pulses are produced if 1 VERTICAL MODE switch is set to CHOP 2 Dual trace vertical unit is operating in the chopped mode and that unit is being displayed The repetition rate of the negative going Vertical Chopped Blanking pulse output at pin 4 is a two megahertz for of the above conditions as determined by the clock 3 16 generator stage Table 3 10 shows the input output combinations for the Vertical Chopped Blanking stage The delay ra
92. A14J270 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A143271 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A143402 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A14403 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 142472 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 5142473 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 14 496 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 141236 108 0734 00 COIL RF FIXED 163NH TK1345 108 0734 00 141 238 108 0734 00 COIL RF FIXED 163 TK1345 108 0734 00 141246 108 0734 00 COIL RF FIXED 163NH TK1345 108 0734 00 141248 108 0734 00 COIL RF FIXED L63NH TK1345 108 0734 00 A14L436 108 0734 00 COIL RF FIXED 163NH TK1345 108 0734 00 A14L438 108 0734 00 COIL RF FIXED 163NH TK1345 108 0734 00 141 445 108 0734 00 COIL RF FIXED 163NH TK1345 108 0734 00 A14L448 108 0734 00 COIL RF FIXED 163NH 1345 108 0734 00 141480 108 0324 00 COIL RF FIXED 10MH 76493 70F102A1 A14Q254 151 0302 00 TRANSISTOR 51 0 18 04713 51899 140454 151 0302 00 TRANSISTOR NPN SI TO 18 04713 51899 A14R201 321 0164 00 RES FXD FILM 499 0HM 125 0 125W TC TO 19701 5033ED499ROF A14R202 321 0164 00 RES FXD FILM 499 OHM 1 0 125W TC TO 19701 5033ED4S99ROF A14R205 315 0103 00 RES FXD FILM 10K GHM 5 0 25W 19701 5043CX10K00J 148208 321 0164 00 RES 499 OHM 1 0 125W TC T
93. A22 Low Voitage Regulator Board Checks and Adjustment 7904A Part ll Adjustment and Performance Check TABLE 5 4 Power Supply Tolerances Output Voltage Limits Power Supply 49 8 to 50 2 volts 14 85 to 15 15 volts 4 9 to 5 1 volts 14 85 to 415 15 volts 49 5 to 50 5 volts TP 50 V Sense 50S TP 15 V Sense 15S TP 6 Sense 58 TP 15 V Sense 155 TP 50 V Sense 505 b INTERACTION if the power supplies are not within the tolerances given in Table 5 4 repeat steps 1 and 2 Disconnect the precision dc voltmeter NOTE Regulation of the individual power supplies can be checked using the procedure given under Troubleshooting Techniques in the Maintenance section d Turn the 7904A off e Disconnect the line cord from the power source f Reinstall the power unit and reconnect the line cord 5 37 Checks and Adjusiment 7904A Part and Performance Check B Z AXIS AND DISPLAY Test Oscilloscope with 10X probe Amplifier 1 3 4 Time Base two required 5 Precision DC Voltmeter DVM 6 Low Frequency Sine Wave Generator 10 Signal Standardizer two needed B1 Z AXIS AND DISPLAY PRELIMINARY SETUP a Perform the Adjustment and Performance Check Power Up Sequence b Refer to Section 6 Instrument Options and to the Change Information at the rear of this manual for any modifications whi
94. ALT OUT 04428 4593 51 Figure 3 2 Breakdown of separate stages within Horizontal Logic 04428 Only two combinations of input conditions to U4428 will produce A Sweep Inhibit level as shown by Table 3 3 During nondelayed operation the first combination disables the A Sweep while the B sweep is being displayed in the ALT horizontal mode both units must be in time base mode The second combination disables the sweep during delayed sweep operation enabling the B sweep to complete its holdoff before the next sweep begins B Sweep Lockout The B Sweep Lockout stage produces an output level at the coliector of Q4468 determining whether the B HORIZ time base unit can produce a sweep HI output level locks out inhibits the B HORIZ unit and a LO level enables the HORIZ unit to produce a sweep The output of this stage is only under one set of input conditions to U4428 as shown by Table 3 4 This set of conditions disables the B sweep while the sweep is being displayed in the ALT HORIZONTAL MODE switch position if both time base units are in a sweep mode and nondelayed sweep is used For any other combination of input conditions the B Sweep Lockout Theory of Operation 7904A TABLE 3 3 Input Output Combinations for Lockout U4428 Pin 14 INPUT OUTPUT HAS NO EFFECT IN THIS CASE TABLE 3 4 Input Output Combinations for B Lockout U4428 Pin 15 level is
95. AVAILABLE USE A24 REV JUL 1987 7 61 Replaceable Electrical Parts 7904A Tektronix No Part No A25 670 8052 00 A25P20 131 1149 00 25 21 131 1149 00 A25P22 131 1149 00 7 62 Serial Assembly No Effective Dscont Mfr Name amp Description Code CIRCUIT BD ASSY FRONT PANEL DISPLAY 80009 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 QUANTITY OF 2 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 QUANTITY OF 2 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 QUANTITY OF 2 Mfr Part No 670 8052 00 131 1149 00 131 1149 00 131 1149 00 REV JUL 1987 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr t No Part No Effective Dscont Name amp Description Code Part Mo 26 670 8053 00 CIRCUIT BD ASSY FRONT PANEL DISPLAY 80009 670 8053 00 26 20 131 1149 00 CONTACT ELEC CKT 8D EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A26P21 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 26 22 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80000 131 1149 00 QUANTITY OF 2 REV JUL 1987 7 63 Replaceable Electrical Parts 7904 Tektronix No Part No A27 670 4346 00 A27CR2235 152 0333 00 A27CR2236 152 0333 00 A27CR2237 152 0333 00 A27CR2238 152 0333 00 A27CR2239 152 0333 00 A27CR2240 152 0333 00 A27CR2241 152 0333 00 A27CR2242 152 0333 00 A27CR2243 152 0333 00 A27CR2244 152 0333 00 A27CR2245 152 0333 00 A27C
96. Anode Multiplier to an Intensity Reference Voltage for use in the Z Axis Logic and Auto Focus circuits The Control Rectifier and Low Voltage Regulator circuits provide the power necessary to operate the instrument These voltages are connected to all circuits within the instrument DETAILED CIRCUIT OPERATION A detailed description of the electrical operation and relationship of the circuits in the 7904A Oscilloscope mainframe is provided in this section The theory of operation for circuits unique to this instrument is described in detail in the discussion Circuits commonly used in the electronics industry are not described in detail For more information on LOGIC FUNDAMENTALS Digital logic techniques are used to perform many functions within the instrument The function and operation of the logic circuits are described using logic symbology and terminology which aid in the understanding of these symbols and logic concepts but is not a comprehensive discussion of the subject For further information on binary number systems and the associated Boolean algebra concepts the derivation of logic functions or a more detailed analysis of digital logic refer to available textbooks SYMBOLS The operation of circuits in this instrument which use digital techniques is described using the graphic symbols set forth in ANSI standard Y32 14 Table 3 1 provides a basic logic reference for the logic devices used within this instrument Any devi
97. C2 SETUP CONDITIONS 7904A Controls No change in settings gsm DC Voltmeter DVM mi Test Equipment Controls Precision DC Voltmeter OVM Appropriate range for voltage to be measured 4593 512 Set the 4 V and 0 4 V CALIBRATOR pushbuttons to the pressed in position b Connect the precision dc voltmeter DVM to the CALIBRATOR output connector c CHECK for a DVM reading of 0 4008 volt within the limits of 0 4004 to 0 4012 volt d ADJUST the 0 4 V ADJ R385 on the AS Mode Switch Board for a meter reading of exactly 0 4008 volt Access to adjustment is through the chassis inside the right vertical compartment near the front of the instrument and under the VERTICAL MODE switch 5 45 Checks and Adjustment 7904A Part li Adiustment and Performance Check C3 CHECK ADJUST CALIBRATOR 1 kHz REPETITION RATE A5R375 NOTE If the preceding step was not performed first perform step C1 then proceed a SETUP CONDITIONS 7904A Controls CALIBRATOR 4 V pushbutton in Test Oscilloscope b C Coaxial Cable d CALIBRATOR Cable q External e Trigger Input BNC Connector Coaxial Cable f Time Mark Generator g Test Equipment Controls Time Mark Generator Test Oscilloscope Triggering input Coupling Sweep Rate Vertical Mode 5 46 NOTE A frequency counter with an accuracy of at least 01 may be used to adjust the CALIBRATOR repetition rate Connect i1
98. C330C104MSUTCA 0801 547 5 0102 871 533E103P DHR15Y5S102M 4KV DHR15Y5S102M 4KV DHR15Y5S102M 4KV DHRi2Y5S102M3KV 845 534Z5U0303Z DHR15Y5S102M 4KY DHR15Y5S102M 4KY 15 55102 4 564 2021 2037 DHR28Y5S682M 4 DHR28Y5S682M 4 554 2021 2037 DHR28Y5S682M 4 DHR28Y5S682M 4 ECEA2CS4R7 ECEAZCS4R7 2RDPLZ007 3P90CC DHR15Y5S102M 4KV 831 610 Y5U0102P 831 610 Y5U0102P 871 533 103 871 533E103P 871 533 103 871 533 103 FDH5004 FDH5004 FDH5004 FDH5004 FDH5004 FDH5004 5004 FOHS004 FDH5004 FDH5004 FDH5004 5004 CX345 CX345 960 OR 95 960 OR BYV95C FDH5004 FDH5004 FDH5004 FDH5004 154017 JH005 3011JA JH005 3011JA H005 3011JA JH005 3011JA JH005 3011JA REV JUL 1987 Tektronix ent No Part 200590 150 0035 00 2006113 150 0035 00 20 20 131 0608 00 20 35 131 0589 00 20 40 131 0589 00 20 83 131 0608 00 20 146 131 0608 00 200129 151 0279 00 20814 308 0123 00 A20R16 301 0272 02 20617 315 0100 02 20818 315 0472 03 A20R19 315 0472 03 20831 301 0155 00 A20R32 301 0155 00 A20R33 315 0104 03 A20R37 315 0183 03 A20R38 315 0226 01 AZOR42 315 0202 02 A20R43 315 0104 03 A2ORAA 315 0105 03 A20R52 307 1135 00 A20R55 311 1968 00 20861 301 0305 01 A20R62 301 0225 02 A20R63 315 0103 03 A OR65 311 1284 00 A20R66 315 0123 00 A20R67 315 0183 03 AZORES 315 0226 01 A20R72 315 0101 03 A2OR73 315 0104 03 A20R84 31
99. Check is to be performed the items required for Adjustment are not required and are so indicated by footnote 1 The remaining test equipment is common to both procedures The specifications for test equipment given in Table 5 3 are the minimum required to meet the performance requirements Detailed operating instructions for test equipment are omitted in these procedures Refer to the test equipment instruction manual if more information is needed POWER SOURCE CONT Part Part il Performance Adjustment and Pertormance Check Procedure Title Performance Check Procedure Title Does not normally require customer verification Satisfactory operation is substantiated at the factory SPECIAL FIXTURES Special fixtures are used only where they facilitate instrument adjustment These fixtures are available from Tektronix Inc Order by part number from Tektronix Field Offices or representatives TEST EQUIPMENT ALTERNATIVES of the listed test equipment is required to completely check and adjust this instrument However complete checking or adjusting may not always be necessary or desirable You may be satisfied with checking only selected characteristics thereby reducing the amount of test equipment actually required The checks and adjustment procedures in Part are based on the first item of equipment given as an example When other equipment is substituted control settings or setups may need to be
100. DA2527 1N4152 JWM B7059 JWM B7 059 JWM B7059 48283 036 51899 51899 51899 57899 57899 51899 51899 51899 57898 5 3195 57898 5033 010 0 5033 010 0 RB14FXE30K1 14 1 20002 3386F T04 204 5033 020 00 5033ED100KO0F 3386F T04 104 5033 16 20 5033ED100KO0F 3386 04 503 SO43ED8K250F CEADSLIOLF 7 41 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr ent No Part No Effective _ Dscont Name amp Description Code Mfr Part No 168525 311 1230 00 5 20K OHM 0 SW 32997 3386F 104 203 ALBR526 321 0314 00 RES FXD FTLM 18 2K OHM 125 0 125W TC TO 19701 5043ED18K20F 168529 321 0326 00 RES FILM 24 3K OMM 125 0 125W TC TO 19701 5043ED24K30F 15 530 311 1230 00 RES VAR NONW 20K OHM 0 58 32997 3386 704 203 168531 321 0450 00 RES FILM 475 1 0 125 1 70 19701 5043E0475K0F 168532 321 0450 00 RES FXD FILM 475K OHM 135 0 1254 TC TO 19701 5043 0475 0 A16R535 311 1235 00 RES VAR 100 OHM 0 5W 32997 3386 04 104 A16R536 315 0104 00 RES FILM LOOK OHM 525 0 25W 57668 NTR25J E100K A16R537 315 0244 00 RES FXD FILM 240K OHM 55 0 25W 19701 50430 240 0 A16R538 321 0326 00 RES FXD 24 3K 125 0 125W TC TO 19701 5043ED 4K30F 158542 323 0168 00 RES FILM 549 OHM 12 0 54 TC TO 19701 5053RD54
101. DI 1 3PF 100V CAP 01 470 10 100 CAP 01 100PF 10 100V 01 07 54 50 FXD ELCTLT 220 50 10 10 PLASTIC 0 0047UF 5 100V CAP FXD ELCTLT 22UF 450 105 25V CAP ELCTLT 2202 50 10 25V CAP FXD MICA DI 105PF 1 300V CAP FXD CER DI 5 6PF 0 5PF 100V CAP FXD MICA DI 890PF 2 100V FXD CER DI 0 1UF 207 50V CAP FXD CER 01 130 5 100 CAP 01 7 45 25 D1 0 1UF 20 50V CAP FXD ELCTLT 4 7UF 975 1025 35VDC CAP FXD CER DI 2200PF 2025 200V CAP FXD CER 01 100 10 1000 CAP D1 0 20 50 CAP FXD CER D1 0 01UF 1025 100V 01 1000 10 100 DVC DI SCHOTTKY BARR SI 15V D0 35 SEMICOND DVC DI SCHOTTKY BARR SI 15V D0 35 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 SEMICOND DVC D1 5W 51 30V 150MA 30V 00 35 CONTACT ELEC DUAL TOP BERYLLIUM COPPER CONTACT ELEC DUAL BOTTOM CU BE CONN RCPT ELEC CKT BD MT 3 PRONG RCPT ELEC CKT BD MT 3 PRONG CONN RCPT ELEC CKT BD MT 3 PRONG COIL RF VARIABLE 1 3UH COIL RF FIXED 2 7UH COIL RF FIXED 2 7UH COIL RF FIXED 2 7UH COIL RF FIXED 117NH COTL RF FIXED 150NH FIXED 117NH COIL RF FIXED 150NH COIL RF FIXED 1 1UH TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 4 TERMINAL PIN 0
102. FILM 10K 5 0 25 19701 5043 10 00 15 182104 315 0333 00 RES FXD 33K OHM 5 0 25W 57668 25 A15AiR2105 315 0153 00 RES FXD FILM 15K OHM 52 0 25W 19701 5043CX15K00J AL5A1R2107 315 0510 00 RES FXD FILM 51 OHM 5 0 25W 19701 5043CX51R00J A15A1R2108 315 0512 00 RES FXD FILM 5 1K OHM 5 0 25M 57668 NTR25J EOSKI 15 182109 315 0221 00 RES FILM 220 OHM 535 0 254 57668 NTR25 E220E A15A1R 2112 315 0102 00 RES FILM 1K OHM 55 0 25W 57668 NTR25JEO1KO0 15 1 2113 315 0301 00 5 1 300 08 5 0 250 57668 252 00 A15A1R2122 315 0432 00 RES FXD FILM 4 3K OHM 52 0 258 57668 NTR253J EO4K3 1 182123 315 0683 00 RES 68K OHM 5 0 250 57668 NTR253 EG8KO 15 182127 315 0302 00 8 010100 8029999 RES FILM 3K OHM 5 0 250 57668 NTR25J E03K0 A15A1R2127 315 0102 00 8030000 RES FXD FILM 1K OHM 52 0 25W 5 668 25 3 01 0 ALSAIR2128 311 1263 00 8010100 8029999 RES VAR NONW 1K 0HM 102 0 508 32997 3329 158 102 AL5SAIR2129 315 0183 00 8010100 8029999 RES FILM 18K OHM 5 0 25W 19701 5043 18 004 15 182131 315 0472 00 8030000 RES FXD FILM 4 7K OHM 525 0 25M 5 668 NTR25J EOAK7 15 182132 315 0222 00 030000 RES FiLM 2 2K OHM 5 0 25W 57668 252 02 2 15 182134 315 0302 00 8030000 RES FXD FILM 3K OHM 5 0 25W 57668 NTR25J EOS3KQ A15A1R2135
103. FILM 1M OHM 55 0 25W RES FXD FILM 100 OHM 52 0 25W RES FXD FILM 1M OHM 55 0 259 RES FXD FILM OHM 54 0 25M RES VAR NONWW TRMR SK OHM 0 754 RES VAR NONW PNE 5K OHM IM W SW RES FXD FILM 2K OHM 5 0 25W RES FILM 100 55 0 25W RES FXD FILM 2 21K OHM 15 0 1254 TC TO RES FXD FILM 732 1 0 125W TC TO RES FXD FILM 931 17 0 125W 2 RES FXD FILM 430 OHM 52 0 25W RES FILM 51 OHM 54 0 25W RES FXD FILM 909 OHM 175 0 5W TC T0 RES FXD FILM 100 OHM 5 5 0 25M RES FILM 300 OHM 5X5 0 25M RES FXD FILM 47K 535 0 25W RES FXD FILM 100 OHM 545 0 25W RES FXD FILM 12K OHM 5 0 25W RES FXD FILM 330 5 0 25 4 RES FXD FILM 51 OHM 55 0 25 RES FXD FILM 51 OHM 54 0 254 RES FXD FILM 200K OHM 57 0 25W RES FXD FILM 100 OHM 15 0 1254 TC TO RES FXD FILM 5 23K 0HM 1 0 125W TC TO RES FXD FILM 1K OHM 55 0 50W RES FTLM 100 OHM 15 0 1259 TC TO RES FXD FILM 931 OHM 1 0 125W TC 12 RES FXD FILM 22K 5 0 25 RES FXD FILM 1M OHM 1 0 125W TC TO RES FXD FTLM 10 OK OHM 1 0 125 TC TO RES FILM LOOK OHM 55 0 25W RES FXD FILM 100K OHM 5 0 25W RES FXD FILM 10K OHM 5 0 25W RES FXD FILM 24K OHM 55 0 25 RES FXD FILM 820 OHM 5 5 0 25 RES FXD FILM 4 99K OHM 125 0 1254 TC TO RES FXD FILM 8 66K OH
104. Front panel controis connectors and indicators Operating instructions 7904A CAUTION e ELECTRIC SHOCK HAZARD THIS INSTRUMENT MUST GROUNDED i POWER OO NOT REMOVE COVERS REFER SERVICING i QUALIFIED SERVICE PERSONNEL B DISCONNZOT POWER INPUT BEFORE REPLACING 056 FOR CONTINUED HRE HAZARD PROTECTION REPLACE WITH SAME TYPE 45 FAST 250 VOUT FUSE HLUMINATION x UNE YOLTAGE SELECTOR 2 LISTE ELECTRICAL EXECTROWIC M3tASUSING uv amp TCSYING P EQUIPMENT SINGLE mue RESEY i i EL GARATICULL READOUT SINGLE SHO POSTIVE DECREASES lH e mmea ww eeniv gaw fasa By 1900 2308 38 9 ey FUSE FAST FREA 484404 PROBE POWER 2 provide power to active probe system SINGLE SWEEP READY Connector for output of single sweep ready signal from time base unit in A HORIZ compartment SINGLE SWEEP READY Connector for output of single sweep ready signal from time base unit in B HORIZ compartment SINGLE SWEEP RESET Connector for input to externally reset single sweep circuits in A HORIZ and B HORIZ compartments GRATICULE READOUT SINGLE SHOT Connector for input of single shot graticule illumination and single frame readout Z AXIS INPUT Connec
105. OHM 1 0 25W TC TO RES FXD FILM 1 24K OHM 1 0 125W TC TO RES FXD FILM 332 OHM 12 0 125W TC TO RES FILM 10K OHM 5 5 0 25M RES FXD FILM 402 12 0 125W TC TO RES FXD FILM 1 82K OHM 125 0 125W TC TO RES FXD FILM 3 24K OHM 125 0 125W TC TO RES FXD FILM 1K OHM 54 0 25M RES VAR TRMR 250 0 5W RES FILM 43 2 OHM 0 5 0 125W TC T0 RES FXD FILM 365 OHM 1 0 25W TC TO RES FXD FILM 1 01K OHM 120 125 TC TO RES FXD F1LM 9 09K OHM 15 0 125 TC TO RES FXD FILM 3 01K OHM 1 0 25 TC TO RES VAR 500 OHM 0 SW RES FXD CMPSN 51 OHM 5 0 125W RES FXD CMPSN 51 5 0 125 RES FXD FILM 75 0 OHM 125 0 25M TC TO RES VAR NONW 50 20 0 SW RES VAR 1K OHM 1075 0 50W RES FXD FTLM 715 OHM 1 0 125W TC TO RES FXD FILM 768 OHM 1 0 125W TC TO RES FXD CMPSN 20 OHM 5 0 125W RES FXD FILM 51 OHM 5 0 25M RES VAR NONW TRMR 50 20 0 5 RES FXO FILM 180 OHM 12 0 05 TC T9 MET RES VAR 1K OHM 10 0 50W RES FXD FILM 715 OHM 1 0 125W TC TO RES FXD FILM 768 OHM 1 0 125W TC T0 RES FXD CMPSN 20 OHM 5 0 125W RES FXD FILM 51 OHM 5 0 25W RES FXD FILM 316 OHM 1 0 25W TC TO RES FXD FILM 180 OHM 1 0 05W TC T9 MET RES FXD FILM 649 OHM 1 0 25W TC T0 RES FXD FILM 301 OHM 1 0 125W TC TO RES FXO FILM 51 OHM
106. OL HSLNNOO NOILISOd Si 93594 _f O3AIE3O3H AOHS 319NIS ASIINAC GHOM AYTSA ONY WvHDOHd OL HOLIMS T3A31 ALISNALNI inOQVviu O1 193 NV TENA iq3002N3 A3IAN3QI SVM inoavid oi SNION Id AV IdSIG HOLIMS ANVYE XIHLYW 5 H3l0VHYVHO U312VHVHO 123135 LOIS 3WI 1 SNALUMOHS ifidino 8 40 9 SS1 NI NOILYOO1 OL dOd VLVG 149 NOLLISOd GAGOONA 38015 gt 4 lt 7 SVM SVM 61015 JWEL SIHL LN3S3Hd OL VSL viva AOFHS 8 20 9 amp SL SIHL Si viva CHVA 3S ind NOLLVINHOZINI LOIS 3414 d pe adout System by the Re ton Flow chart for character generat 18 Figure 3 REV 1985 3 38 shows the area of the graticule where the from each plug in unit is displayed Notice that Channel 1 of each plug in unit is displayed within the top division of the CRT and Channel 2 is displayed directly below within the bottom divi sion Figure 3 10 shows a typical display where only Chan nei 2 of the Right Vertical and B Horizontal units is selected for display Each word in the readout display can conta
107. PNP SI T0 92 TRANSISTOR PNP SI TO 92 TRANSISTOR PNP 51 TO 92 TRANSISTOR PNP SI TO 72 TRANSISTOR SELECTED 80008 151 0190 00 80009 151 0221 00 80000 151 0221 00 80008 151 0221 00 80009 151 0221 00 80009 151 0220 00 80009 151 0220 00 80009 151 0220 00 80009 151 0220 00 04713 557144 04713 557144 7 65 Replaceable Electrical Parts 79044 Tektronix Serial Assembly No Mfr ent No Part No Effective Dscont Name amp Description Code _ Mfr Part No A280630 151 0198 00 TRANSISTOR SELECTED 04713 5 58802 1 A28Q640 151 0220 00 TRANSISTOR PNP SI 10 92 80009 151 0220 00 A280810 151 0220 00 TRANSISTOR PNP SI TO 92 80008 151 0220 00 A28Q820 151 0220 00 TRANSISTOR PNP ST TO 92 80009 151 0220 00 280830 151 0190 00 TRANSISTOR NPN SI TO 92 80009 151 0190 00 A28Q850 151 0302 00 TRANSISTOR NPN SI TO 18 04713 51899 280910 151 0274 00 010100 8010140 TRANSISTOR NPN Si TO 5 04713 557394 A28Q910 151 0274 01 010141 TRANSISTOR SCREENED 04713 557304 280920 151 0270 00 010100 8010140 TRANSISTOR PNP S1 0 5 04713 57919 280920 151 0070 03 010141 TRANSISTOR SCREENED 04713 51919 280930 151 0270 00 8010100 8010140 515 08 51 10 5 04713 51919 A28Q930 151 0270 03 8010141 TRANS 15705 SCREENED 04713 51919 280940 151 0274 00 8010100 8010140 TRANSISTOR NPN SI TO 5 04713 557394 280940 151 0274 01 8010141 TRANSISTOR SCREENED 04713 557394 A28R100 315 0100 00 RES FXD F1LM 10 OHM 5
108. Parts 7904 Name amp Description TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 9 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 7 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TRANSISTOR SELECTED RES FILM 47 5 0 25W RES FXD FTLM 4 99K OHM 1 0 125W TC TO RES FXD FILM 4 99K OHM 1 0 125W TC TO RES FXD FILM 47 OHM 5 0 25W RES FXD FILM 4 99K OHM 15 0 1254 TC T0 RES FILM 4 99K OHM 1 0 125W TC TO RES FXD FILM 4 7K OHM 5 0 25W RES FXD FILM 47 OHM 52 0 25W RES FXD FILM 3K OHM 5 0 25W RES FILM 2K OHM 5 0 25W RES FXD FILM 2K OHM 5 0 25W RES FXD FILM 2K OHM 5 0 25W RES FXD FILM 1K OHM 54 0 25V RES FXD FILM 47 OHM 55 0 25W RES FXD FILM 24K OHM 5 0 25W RES FILM iM OHM 5 0 25W RES FXD FILM 1 5K OHM 52 0 25W RES FILM 10K OHM 525 0 25W RES FXD FILM 1 5K OHM 5 0 25W RES PXD FILM 2K OHM 54 0 258 RES FILM 1 3K OHM 54 0 25W RES FXD FILM 47 OHM 5 0 25w RES FILM 2 49K OHM 1 0 125W TC TO RES FXD FILM 453 OHM 12 0 5W TC TO RES FXD FILM 2 49K OHM 1 0 125W TC TO RES FXD FILM 1 3K OHM 5 0 25W RES FXO FILM 1 3K OHM 5 0 25W Mfr Code Part No 22526 22526 22526 04713 57668 19701 19701 57568 19701 19701 57668 57668 57668 57668 57668 57668 57668 57868 57668 19701 57668 1
109. Preventive maintenance when performed on a regular basis can prevent instrument breakdown and may improve the reliability of the instrument The severity of the environment to which the instrument is subjected wil determine the frequency of maintenance A convenient time to perform preventive maintenance is before electrical adjustment of the instrument CABINET PANEL REMOVAL WARNING avoid personal injury not touch sharp edges on instrument covers instruments equipped with Option 3 meeting specifications have thin metal seals that could cause cuts and scratches Dangerous potentials exist at several points throughout this instrument When the instrument is operated with the covers removed do not touch exposed connections or components Some transistors have voltages present on their cases Disconnect power before cieaning the instrument or replacing parts The side top and bottom cabinet paneis provide protection to personnel from operating potentials present within the instrument addition they reduce radiation of electromagnetic interference from the instrument The cabinet panels are held in place by slotted fasteners To remove the panels turn each fastener counterclockwise a quarter turn with a large screwdriver Lift the panels away Operate the instrument with the panels in place to protect the interior from dust CLEANING The 7904A should be cleaned as often as operating conditions req
110. Q4448 saturates and its collector goes positive to forward bias Q4456 During the time the A sweep is being displayed the Display B Command is LO This reverse biases Q4442 and Q4448 Q4456 is reverse biased so the VERT TRACE SEPARATION B control is disconnected while the A sweep is being displayed When the HORIZONTAL MODE switch is set to B only HI level is connected to the emitter of Q4442 through R4431 This reverse biases Q4442 even though the Display B Command at its base is HI for this mode Therefore the VERT TRACE SEPARATION B control has no effect When the VERTICAL MODE switch is set to ALT and the Delay Mode Control level from the A time base unit is LO indicating nondelayed sweep operation a HI level is applied to the emitter of Q4442 through R4438 and CR4434 This HI level reverse biases Q4442 even though the Display B Command is This action disconnects the VERT TRACE SEPARATION B contro for independent pairs operation so that the vertical position of the B sweep display is determined by the slaved LEFT VERT plug in unit only delayed sweep operation is selected the Delay Mode Control Out level is forward biasing 04438 04443 This allows the VERT TRACE SEPARATION B control to position the B sweep display since independent pairs operation is not possible when operating in a delayed sweep mode A logic diagram of the Trace Separation stage is shown in Figure 3 7A The discrete comp
111. R82 and R83 The Inverter Current Limiter takes control of regulation when pin 13 reaches near zero volts Peak Inverter current is limited to about 5 amperes If the voltage at pin 13 remains near zero for more than about 10 milliseconds pin 8 will go positive to turn off the Inverter Fault Sense The fault sense portion of U75 provides overload protection for supplies on the Low Voltage Regulators and Fan Board schematic diagram 15 and other supplies generated throughout the instrument Resistive networks from supplies are connected to the Fault Sense input at pin 2 of U75 During normal operation ADD NOV 1985 the voltage at the Fault Sense input remains near zero one of the inputs changes sufficiently to cause this voltage level to vary 200 millivolts positive or negative for more than 10 milliseconds a positive output at pin 8 of U75 stops the Inverter Line Stop The line stop portion of U75 stops the Inverter when the POWER switch on the front panel is turned OFF The Line Stop stage will also stop the Inverter if the ac line voitage falls beiow a minimum value The line frequency signal from transformer is connected to 4 the Line Stop Sense input of 1 75 During normal operation the line frequency signal causes the Line Stop Timer terminal pin 3 to periodically discharge to ground When the line frequency signal is interrupted or falls below a minimum value C67 will charge to approximately 0 7
112. Rectifier schematic diagram number 14 in Section 8 Diagrams and Circuit Board illustrations Note the polarity amplitude and shape of the waveform present at each test point Adjust the vertical deflection factor of the test oscilloscope as necessary to maintain an on screen display Look for a power supply where the burst voltage is very low in relation to the specified supply voltage 6 When a low supply voltage is found disconnect the 7904A from the power source and discharge the line storage capacitors Fig 4 5 following the procedure given under Access to Components in the Power Supply Unit Check for shorted components in the suspected power supply also check the filter capacitors for leakage TABLE 4 4 Burst Voltage Test Points Pre Regulated Power Test Point Located On A12 Control Rectifier Board 108 V TP126 _ 54 Pin4ofP52 _ V Pin6ofP52 Pi2otP5322 Pin 7 of P50 Pin 3 of 52 45 V Lights Pin 100f P82 mm VARIES WITH LOAD B C1988 115 Figure 4 4 Current sensing waveform at 12884 Maintenance 7904A Step D Check Line input Circuit To check the input circuit perform the following procedure 1 Disconnect the 7904A ihe variable autotransformer and discharge the line storage capacitors Fig 4 5 foll
113. SI6 SI 225V 0 2A D0 7 SCHOTTKY BARR SI 15V D0 35 SW SI 30V 150MA 30V 00 35 5 S1 30V 150MA 30V 00 35 SW 1 30V 150MA 30V DO 35 SW S1 30V 150MA 30V 00 35 SM S1 30V 150MA 30V 00 35 SW SI 30V 150MA 30V 00 35 SW S1 30V 150MA 30V D0 35 SEMICOND DVC DI SW ST 30V 150 30V 00 35 Su ST 30V 150MA 30V 00 35 SM ST 30V 150 30V D0 35 SW SI 30 150 30V D0 35 SW SI 30V 150MA 30V 00 35 SW ST 10V 50MA DO 7 SW SI 30V 150 30V D0 35 SW 1 30V 150MA 30V DO 35 SEMICOND 0 01 SW ST 30V 150MA 30V 00 35 SW GE 22V B0Md DO 7 SCHOTTKY SW 51 70V D0 35 SW GE 22V 80MW DO 7 SW 1 30V 150 30V 00 35 194 51 30V 150MA 30V D0 35 RECT SI 20V A59 S4 1 30V 150MA 30V D0 35 SW 51 30V 150MA 30V 00 35 SW S1 30V 150MA 30V 00 35 RECT SI 20V 1A A59 CONN RCPT ELEC CKT BD MT 3 PRONG CHOKE RF FIXED 3 9UH CHOKE FIXED 3 9UH CHOKE RF FIXED 3 9UH Mfr Code Mfr Part No 80008 04222 04222 04222 04222 54473 00853 52763 04222 52763 52763 59660 52763 52763 59660 00853 52763 52763 59821 52763 52763 05397 04222 59660 04222 59660 07263 50434 03508 03508 03508 03508 03508 03508 03508 03508 03508 03508 03508 03508 07263 03508 03508 03508 14433 80009 14433 93508 03508 04713 03508 03508 03508 04713 80009 76493 26493 76
114. ST 55V 200MA 00 35 SEMICOND DVC DI SW S1 55V 200MA 00 35 SEMICOND DVC DI SW SI 55V 200MA D0 35 SEMICOND DVC D1 SW ST 55V 200MA 20 35 SEMICOND DVC DI 5W SI 55 200 D0 35 SEMICOND DVC DI 5W SI 55V 200 00 35 SEMICOND DVC DI 5W SI 55V 200MA 00 35 SEMICOND DVC DI SW SI 55V 200MA 00 35 Mfr 80009 80009 59821 55112 05397 59660 05397 59821 55112 05397 05397 05397 55112 05397 55112 00853 59660 59660 59660 59660 59821 05397 54473 14731 56289 14752 56289 56289 54473 54473 54473 54473 54473 54473 54473 54473 55680 55680 54473 55680 54473 04222 55112 05397 55112 07263 07263 03508 03508 07263 07263 07263 07263 07263 07263 07263 07263 Code Mfr Part No 670 5959 03 670 5959 04 010324075 185 0 01 K 63AAA T368B275M050AS 0805585 550222 1320A275K015AS D103740Z 5UJDCEX 185 0 01 K 63AAA T368A225MO20AS T368B275M050AS T368A105M035AZ 185 1 0 K 50 AGA T368A105M035AZ 185 1 0 K 50 AGA 0151 102 0 855 535U2J101J 838533X5F02715 855 535U2J101J 838533X5F02715 20006082237 T368A274M050AZ ECE ASON1 230B1C105M 192 10392 65081 224 5020227 5020227 ECE A100V10L ECE AT00V10L ECE A 00V10L ECE AL00V10L ECE BIEV30S ECE A25V100L ECE BIEV30S ECE A25V100L ULALA221TPA2 ULALAZ2 1 TPA2 1025 1 221 2 ECE A6V47L SR302E1 0SZAATR 185 1 0 K 50 AGA C330C104M5U1CA 185 0 1 K 63 ABA 60
115. SW SI 30V 150MA 30V DO 35 03508 DA2527 10152 A22CR20 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V DO 35 03508 D4A2527 184152 A22CR21 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V DO 35 03508 2527 184152 A22CR22 152 0333 00 SEMICOND DVC D1 5M 1 55V 200MA 00 35 07263 FDH 6012 A22CR28 152 0066 03 SEMICOND DVC DI RECT SI 400V 1A DO 41 14433 164017 A22CR45 152 0333 00 SEMICOND DVC D1 5W SI 55V 200MA DO 35 07263 6012 A22CR49 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 2527 1N4152 A22CR50 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 2527 14152 A22CR51 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 2527 1N4152 A22CR52 152 0333 00 SEMICOND DVC DI SW S1 55V 200MA 00 35 07263 FDH 8012 A22CR58 152 0066 03 SEMICOND DVC DT RECT ST 400V 1A DO 41 14433 164017 A22CR64 152 0333 00 SEMICOND DVC D1 SV S1 55V 200MA D0 35 07263 6012 A22CR76 152 0066 03 SEMICOND DVC DI RECT SI 400V 1A 00 41 14433 164017 A22CR84 152 0333 00 SEMICOND DVC D1 SW S1 55V 200MA DO 35 07263 FDH 6012 A22CR96 152 0066 03 SEMICOND DVC DI RECT SI 400V 1A D0 41 14433 164017 20 8114 152 0333 00 SEMICOND DVC DI SW SI 55V 200MA D0 35 07263 FDH 6012 A22CR132 152 0066 03 SEMICOND DVC DI RECT SI 400V 1A D0 4i 14433 164017 A22CR142 152 0423 00 SEMICOND DVC DI RECT SI 400V 3A M176A 04713 105000 A22CR143 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 2527 1N4152 A22CR144 1
116. Signal Standardizer Vert or Horiz Gain Vert or Horiz Com Mode 4593 530 4 4593 529 a Align the bright vertical trace with the center vertical a EXAMINE the vertical trace it should be within 0 5 graticule line use the signal standardizer Position division of the center vertical graticule line control b ADJUST CTR adjustment R121 on the A28 b CHECK that the second and tenth vertical traces Horizontal Amplifier Control Board to align the align with the second and tenth graticule lines displayed trace with the center vertical graticule within 0 08 division line c ADJUST Gain adjustment R230 on the A28 c Move the signal standardizer to the B HORIZ Horizontal Amplifier Board for eight divisions of compartment and change the HORIZONTAL MODE deflection between the second and tenth graticule switch to B lines d EXAMINE the vertical trace it should be within 0 5 d CHECK along the horizontal graticule line for 0 05 division of the center vertical graticule line division or less error at each vertical graticule line intersection e ADJUST if necessary compromise the setting of R121 for optimum centering for both horizontal e Move the signal standardizer to the HORIZ compartments If readjustment is necessary repeat compartment and change the HORIZONTAL MODE parts a b c and d of this step switch to A f CHECK that the deflection between the second and tenth gratiucle lines is the same as in part
117. T0 19701 5033 01 50 AL5AIR2229 315 0512 00 8030000 RES FILM 5 1K OHM 525 0 25M 57668 25 5 15 182230 315 0103 00 8030000 RES FILM LOK OHM 5 0 25W 18701 5043 10 004 A15AIR2231 315 0303 00 8010100 8029999 RES F1LM 30K OHM 525 0 25W 19701 5043 30 000 A15A1R2235 315 0203 00 RES FXD FILM 20K OHM 54 0 25W 57668 NTR25J E 20K A15A1R2236 315 0203 00 RES FXD FILM 20K OHM 525 0 25W 57668 2 1 20K 15 182237 315 0203 00 RES FILM 20K 5 0 25 57668 NTR25J E 20K A15A1R2238 315 0203 00 RES FILM 20K OHM 52 0 25W 57668 NTR25J E 20K 15 1 2239 315 0303 00 8030000 8031859 RES FILM 30K OHM 525 0 25W 19701 5043CX30K00J A15A1R2239 315 0104 00 8031860 RES FILM 00K OHM 5 0 258 5 668 NTR25J ET00K A15A1R2241 321 0326 00 10100 8029999 RES FILM 24 3K 125 0 125W TC TO 19701 5043 024 30 2242 321 0259 00 8030000 RES FILM 4 87K 1 0 1254 70 07716 CEAD48700F 15 182243 311 2230 00 8030000 RES VAR 500 20 0 50 LINEAR 450 GFO6UT 500 15 182244 321 0326 00 8030000 RES FILM 24 3K 1 0 1254 10 19701 5043ED24K30F AL5AIR2245 315 0472 00 8030000 RES FILM 4 7K OHM 5 0 253 57668 NTR25J EO4K7 A15A1R2246 307 0445 00 8030000 RES NTWK F1 4 7K OHM 20 S RES 32997 4310 101 472 A15A1R2247 3
118. TC T0 24546 86003650 Al4R264 321 0201 00 5 1 21 08 1 0 1254 1 70 19701 5043 01 210 A14R265 321 0285 00 RES FILM 9 09K OHM 1 0 125W TC TO 07716 JCEADS0900F 148270 311 1239 00 RES VAR NONW 2 5K 0 5 32997 3386 07 252 14827 321 0178 00 RES FILM 698 OHM 1 0 125W 0 07716 CEADGOSROF A14R272 315 0510 00 RES FXD FILM 51 5 0 25 4 19701 5043 51 002 148273 322 0239 00 RES XD FILM 3 01K 15 0 254 0 75042 0 3011 Al4R274 311 1248 00 RES VAR NONW TRMR 500 OHM 0 5W 32997 3386X T07 501 145277 317 0510 00 RES XD CMPSN 51 5 0 125 01121 885105 A14R278 322 0085 00 RES FXD FILM 75 0 OHM 125 0 25M TC TO 75042 CEBTO 75RO0F A14R279 311 1936 00 RES VAR 50 0 20 0 5 32997 3386X T107 500 148280 317 0510 00 RES FXD CMPSN 5i 5 0 125 01121 885105 148401 321 0154 00 RES FXD FILM 499 OHM 12 0 125W TC TO 19701 5033ED499ROF 148402 321 0164 00 RES FILM 499 OHM 12 0 125W TC TO 19701 5033ED499ROF Al4R405 315 0103 00 RES FILM 10K OHM 53 0 250 19701 5043 10 00 148408 321 0164 00 RES FXD FILM 499 OHM 122 0 125W TCATO 19701 5033ED499ROF A14R409 321 0164 00 RES FILM 499 OHM 12 0 1254 TC TO 19701 5033ED499ROF 14 412 325 0053 00 RES FXD FILM 50 OHM 1 0 05W TC TO 91637 CMF50 F5OROOF 148413 325 0053 00 RES FXD FILM
119. VERTICAL SYSTEM E2 Check Vertical Amplifier 4 F3 Check Adjust Vertical Amplifier Gain i Gain F4 Check Vertical Low Frequency Linearity Check Vertical Low Frequency Linearity 24 Check Vertical Amplifier 500 MHz Gain 28 Check Vertical Amplifier 500 MHz Gain REV MAR 1984 TABLE 5 2 CONT Performance Check Summary Checks and Adjustment 7904A Part H Part Characteristics Performance Perlormance Check Adjustment Requirements Procedure Title petibus edi VERTICAL SYSTEM CONT Step Response Rise time 10 to 90 with 7A29 Amplifier Unit Isolation Between Vertical Compartments 700 ps or jess check F8 Check Vertical 1 8 Div Signal LEFT RIGHT At least 160 1 from dc to E5 Check Vertical Channel ALT Modes 100 MHz and at least 80 1 Isolation from 100 to 500 Delay Line Permits viewing the leading edge of triggering signal displayed on crt Checked throughout procedure when single pulse is Satisfactory performance substantiated by Frequency Response Amplifier 500 MHz Gain F9 Check Vertical Channel Isolation Difference in Signal Delay Between Vertical Compartments 100 ps or less Does not normally require Vertical Display Modes E6 Check Vertical Display Modes Selected by front panel VERTICAL MODE Swi
120. X Y displays A slide switch located on the Logic board selects how the Z Axis is controlled during X Y displays Normally the switch is in the IN position so that the Z Axis is controlled by a time base unit In the OUT position the HORIZONTAL MODE switch controls the Z Axis Without a vertical plug in unit in a horizontal compartment diodes CR4487 and CR4495 do not conduct Q4488 acts as an emitter follower Resistors 4486 and 4487 perform a dc level shift approximately equal to the emitter base drop of Q4488 Q4492 is 8 DISPLAY B COMMAND B MODE HORIZ ALT MODE VERT DELAY MODE CONTROL Ean MN 84431 4 Theory of Operation 7904A 04456 TRACE SEPARATION AUX Y AXIS OUTPUT SEPARATION B ALL OTHER COMBINATIONS NO OUTPUT HAS NO EFFECT IN THIS CASE Figure 3 7 A Logic diagram of Trace Separation stage B Table of input output combinations turned off so the voltage at the coliector of Q4492 is a duplicate of the Display B Command If diode CR4487 is connected to ground by an amplifier unit in the B Horizontal compartment the Display B Command is not applied to the base of Q4488 and the signal at the collector of Q4492 is LO In this condition the Z Axis logic selects the INTENSITY input only independent of other control inputs If diode CR4495 is connected to ground by a amplifier unit installed in the A
121. Z Axis Board with the probe ground connected to chassis ground EXAMINE test oscilloscope display for a waveform baseline between 8 and 12 volts above ground reference ADJUST the Output Level R135 located on the A21 Z Axis Board for a waveform base line at 10 volts above ground reference Set the 7904A A INTENSITY control fully clockwise and set the test oscilloscope vertical deflection to 1 volt division 10 volts division at the probe tip EXAMINE the test oscilloscope display for a 61 to 65 volt peak to peak waveform Do not move the test oscilloscope vertical Position control 5 39 Checks and Adjusiment 7904A Part ii Adjustment and Performance Check ADJUST the Z Axis Amp Gain adjustment R125 B4 ADJUST Z AXIS TRANSIENT RESPONSE located on the A21 Z Axis Board for a 63 volt 21 180 21 150 A21C155 218150 peak to peak waveform displayed the test A21R155 oscilloscope NOTE h INTERACTION repeat parts d through g until If the preceding step was not performed first the waveform is within the limits specified in parts perform step B1 then proceed d and f B4 SETUP CONDITIONS i Disconnect the probe 7904A Controis HORIZONTAL MODE A INTENSITY Fully clockwise B INTENSITY Fully clockwise w Test Oscilloscope 10X probe Y a E Test Equipment Controls Test Oscilloscope Sweep Rate 0 1 us div Vertical Deflection 50 mV div Variab
122. a partis known this list will identify the assembly in which the part is located CROSS INDEX MFR CODE NUMBER TO MANUFACTURER The Mfr Code Number to Manufacturer index for the Electrical Parts List is located immediately after this page The Cross index provides codes names and addresses of manufac turers of components listed in the Electrical Parts List ABBREVIATIONS Abbreviations conform to American National Standard Y 1 1 COMPONENT NUMBER column one of the Electrical Parts List numbering method has been used to identify assemblies subassemblies and parts Examples of this numbering method and typical expansions are illustrated by the following Example a A23R1234 A23 R1234 Circuit number Read Resistor 1234 of Assembly 23 component number Assembly number Example b component number A23A2R1234 A23 A2 R1234 Assembly Subassembly Circuit number number number Read Resistor 1234 of Subassembly 2 of Assembly 23 Only the circuit number will appear on the diagrams and circuit board illustrations Each diagram and circuit board illustration is clearly marked with the assembly number Assembly numbers are also marked on the mechanical exploded views located in the Mechanical Parts List The component number is obtained by adding the assembly number prefix to the circuit number The Electrical Parts List is divided and arranged by assemblies in numerical sequence e g assembly A1
123. about 80 volts Spark gap electrodes E8 and E13 are surge voltage protectors When the LINE VOLTAGE SELECTOR Switch is in the 115 voit position only 8 is connected across the line input If a peak voltage greater than 230 volts is present on the line will conduct and quickly open line fuse F10 to interrupt the input power before the instrument can be damaged In the 230 volt position E8 and E13 are connected in series across the line input to provide protection for peak voltages greater than 460 volts Transformer T8 provides a sample of the line voltage to the plug in connectors for triggering at line frequencies This line frequency signal is also connected to the Inverter Control stage to sense when line voltage is present INVERTER START Components R10 and C42 provide a turn on path between the input line and the negative side of line input filter capacitor C17 Capacitor C42 charges on each cycle of the input line voltage When the charge on C42 reaches about 33 volts Zener diode VR38 turns on which causes Q30 the programmable unijunction transistor to fire This provides base drive to turn on Q40 through C39 When Q40 turns on it shock excites series resonant network L37 and C37 to generate a damped oscillation This damped oscillation provides the drive necessary to start the Inverter switching action After the Inverter is operating the recurrent waveform at the collector of Q40 keeps C42 discharged through 4
124. an end lead pin connector is used which mates with the interconnecting pin The following information provides the removal and replacement procedure for the various types of interconnecting methods Coaxial Type End Lead Connectors Replacement of the coaxial type end lead connectors requires special tools and techniques only experienced maintenance personnel should attempt to remove or replace these connectors We recommend that the damaged cable or wiring harness be replaced as a unit For cable or wiring harness part numbers see Section 9 Replaceable Mechanical Parts An alternative solution is to refer the replacement of the defective connector to your local Tektronix Field Office or representative Figure 4 15 gives an exploded view of a coaxial end lead connector assembly Circuit Board Pins circuit board pin replacement kit including necessary tools instructions and replacement pins with attached ferrules is available from Tektronix inc Order Tektronix Part 040 0542 00 Replacing circuit board pins on multi layer boards is not recommended The multi layer boards in this instrument are listed under Soldering Techniques in this section fo repiace a damaged pin first disconnect any pin connectors Then remove the solder from the connection using an anti static vacuum type desoldering tool see Soldering Techniques Remove the damaged pin from the board with a pair of pliers leaving the ferrule see Fig 4 16 in th
125. and B Sawtooth Output Signals Does not normally require customer verification Satisfactory operation substantiated at factory B5 Check and B Sawtooth C5 Check and B Sawtooth Output Signals C6 Check A and B Gate Output Signals Checks and Adjustment 7904A TABLE 5 2 CONT Performance Check Summary Part Part Characteristics 2 Performance Check 5 sa nal Procedure Title ub SIGNAL OUTPUTS CONT Cont Output Voltage into 50 0 5 V within 1096 Does not normally require customer verification Satisfactory operation substantiated at factory ree n 10 V within 1096 up to 1 us div sweep rate C6 Check and B Gate Output Signals B6 Check and B Gate Output Signals Into 1 MO Does not normally require customer verification Satisfactory operation substantiated at factory Rise Time into 500 5 ns or less Fail Time into 500 15 ns or less ata TT TUTTI E A SIG OUT Selected by TRIGGER Check Trigger Selector D5 Check Trigger Selector SOURCE switch Operation Operation a dpa E RECS MM ENG CM Source i Sameas B TRIGGER SOURCE Output Voltage Into 500 25 mV div of vertical Does not
126. and R384 flows to ground When Q384 is off this current flows through CR386 and R386 3 6 into the voltage divider network of R387 R392 R393 R394 R395 R396 and R397 to produce the 4 volt 0 4 voit and 40 millivolt Calibrator output voltages accuracy of the Calibrator output voltage is set by the 0 4 Volts DC adjustment R385 Both the 4V and 0 4V calibrator switches must be engaged when adjusting R385 The Calibrator frequency is set by the 1 kHz adjustment R375 MODE SWITCHING The Mode Switching circuit includes front panel switching and selection of the vertical and horizontal compartments to provide crt deflection The Mode Switch circuit operates in conjunction with the Logic circuit Diagram 4 to develop control signals for use in other circuits within this instrument and plug in units installed in the plug in compartments Table 3 2 shows the outputs produced with all combinations of the front panel switch positions DISPLAY CONTROL The Display control circuit includes front panel controls for the crt BEAMFINDER switch and amp B INTENSITY It also interfaces the Intensity Reference signal through diodes CR2009 and CR2019 For further discussion about the operation of these diodes see Intensity Limiter description on diagram 7 MAIN INTERFACE Diagram 3 shows the plug in interface and the interconnections between the plug in compartments circuit boards etc of this instrument The signal and voltag
127. and produce a time multiplexed analog volt age output containing all of the column and row information from the plug ins The Column Data Switch and Row Data Switch are sequenced by the binary Channel Address Code from the Channel Counter The time multiplexed output of the Column Data Switch is monitored by the Display Skip Generator to determine if it represents valid information that should be displayed Whenever information is not encoded in a time siot the Dis play Skip Generator produces an output level to prevent the Timer stage from producing the control signals that normally interrupt the CRT display and present a character The analog outputs of the Column Data Switch and Row Data Switch are connected to the Column Decoder and Row Decoder stages respectively These stages sense the magnitude of the analog voltage input and produce an out put current on one of ten lines The outputs of the Column Decoder stage are identified as C 1 through C 10 column 1 through 10 corresponding to the encoded column informa tion Likewise the outputs of the Row Decoder stage are identified as R 1 through R 10 row 1 through 10 cor responding to the encoded row information The row and column outputs are then converted to Binary Coded Deci and used to address memory locations within the Char acter Generator These outputs are also used at other points within the system to indicate when certain informa tion has been encoded One such st
128. and that the negative portion of the trapezoidal waveform at pin 10 is shorter Complete de tails on operation of the Display Skip Generator are given later The Timer operation is also controlled by the Single Shot Lockout level at pin 2 if this level is LO the Timer operates 3 44 as just described However if the Single Shot Lockout Stage sets a Hi level at this pin the Timer stage is locked out and can not produce any output signals see Single Shot Lockout description for further information A negative voltage on the readout intensity line sets the intensity of the readout display independently of the A or B INTENSITY controls The Readout Intensity line also pro vides a means of turning the Readout System off when a readout display is not desired When the Readout Intensity line is left open the current from pin 11 of 02126 is inter rupted and at the same time a positive voltage is applied to pin 4 through CR2124 The positive voltage switches the stage to the same conditions as were present under the Display Skip condition Therefore the CRT display is not interrupted to present characters However time slot pulses continue to be generated TIME SLOT COUNTER Time Siot Counter U2159 is a sequential switch which di rects the trapezoidal waveform input at pin 8 to one of its 10 output lines These time siot pulses are used to interrogate the plug in units to obtain data for the Readout System The trigger pulse at pi
129. any defective parts are located follow the replacement procedures given under Component Replacement in this section Check the performance of any circuit that has been repaired or that has had any electrical components replaced Adjustment of the circuit may be necessary TROUBLESHOOTING THE HIGH EFFICIENCY POWER SUPPLY UNIT GENERAL The following information is provided to facilitate troubleshooting the high efficiency power supply unit information contained in other sections of this manual should be used in conjunction with this procedure to aid in locating a defective component An understanding of the circuit operation is valuable in locating troubles See Section 3 Theory of Operation for this information Specifications for the troubleshooting equipment referred to in this procedure are given earlier in this section under Troubleshooting Equipment WARNING Extreme caution must be used when troubleshooting in the power supply unit due to the line voltage and the high voltage high current potentials present in the unit When a fault condition occurs which is not of sufficient magnitude to open the line fuse power supply protection circuitry will cause the inverter to operate in a pulse mode in this mode the inverter will turn on for a short period of time and then turn off for a longer period of time This cycle repeats until the malfunction is corrected This pulse mode causes either a ticking or a chirping soun
130. as given in Table 5 6B for optimum flat top on the displayed waveform F7 ADJUST HIGH FREQUENCY COMPENSATION 7 A18R404 A18R405 A18C401 R83 A18R215 A18C215 A18L100 NOTE If the preceding step was not performed first perform step F1 then proceed F7 SETUP CONDITIONS 7904A Controls VERTICAL MODE A TRIGGER SOURCE LEFT VERT VERT MODE 5 0 4 w ae 8 1 Time Base Test Equipment Controls Time Base Sweep Rate Pm 2 ns div Triggering Auto AC Internal Positive Siope Signal Standardizer Vert or Horiz Step Resp 4593 540 a Set the signal standardizer Amplitude and Position controls for a six division display centered on the crt Set the time base unit Position control to align the 5096 point of the step with the second vertical graticule line b EXAMINE the transient response for optimum square corner and flat top on the displayed pulse within the following limits Aberrations in the first 5 nanoseconds after the 5096 point of the step should not exceed 0 3 division peak to peak Aberrations from 5 to 10 nanoseconds after the 5096 point of the step should not exceed 0 18 division peak to peak Aberrations after 10 nanoseconds of the 5096 point of the step should not exceed 0 06 division peak to peak except to allow 0 12 division of aberrations for delay line termination at about 130 nanoseconds from the step change time division setting as necessary to vi
131. at its collector The Jump Command is connected to the Word Trigger stage to advance the Channel Counter to the next word and to reset the Time Slot Counter to time siot 1 ZEROS LOGIC AND MEMORY The Zeros Logic and Memory stage 1 2232 stores data encoded by the plug in units to provide zeros adding and prefix shifting logic for the Readout System The Strobe pulse at pin 15 goes positive when the data has stabilized and can be inspected This activates the Zeros Logic and Memory stage so that it can store the encoded data Typical output waveforms of the five possible input conditions that can occur are shown in Figure 3 17 When time siot 1 occurs a store command is given to all of the memories f the piug in units encoded data for column 1 2 3 4 or 10 during time slot 1 the appropriate memory or memories is set Notice that row 3 information from the Row Decoder must also be present at pin 16 for data to be stored in the memory of U2232 If data was encoded during time slot 1 a negative going output is produced at pin 7 while the memories are being set This negative going pulse is connected to the base of Q2229 in the Display Skip Generator to produce a Display Skip output Since the information encoded during time siot 1 was only provided to set the memories and not intended to be displayed on the crt at this time the Display Skip output prevents a readout display during this time slot During time slot 5 a memory with
132. be displayed at one sweep rate while the other signal is displayed at the other sweep rate Four Trace Two dual channel amplifiers can display four separate signals If one time base unit is used all four signals will be displayed at the same sweep rate TIME BASE PLUG IN UNITS The 7904A is compatible with time base units of the 7B10 7 70 7B80 and 7B90 series Sweep rates and triggering ranges should be taken into consideration when selecting time base plug in units To obtain a delayed sweep display a delaying time base unit must be installed in the A HORIZ compartment and a delayed time base unit installed in the HORIZ compartment A delayed sweep display can also be obtained with one horizontal compartment if a dual time base unit is used This leaves the other horizontal compartment available for other plug in units as suggested later in this section NOTE The 7 50 time base units are not recommended for use with this instrument because they require a longer delay line than is used in the 7904A Therefore the leading edge of the triggering event may not appear on the display SAMPLING DISPLAYS Sampling system plug in units for the 7000 series oscilloscopes provide displays of fast changing signals that cannot be examined using any other method For example sampling systems available for the 7904A can resolve repetitive signals having less than 10 millivolts of peak amplitude and occurring in less
133. be tilted up about 109 for more convenient crt viewing PACKAGING FOR SHIPMENT If this instrument is to be shipped for long distances by commercial transportation it is recommended that the instrument be packaged in the original manner The carton and packaging material in which your instrument was shipped should be saved and used for this purpose Also if this instrument is to be shipped to a Tektronix Service Center for service or repair attach a tag to the instrument showing the following Owner of the instrument with address the name of a person at your firm who can be contacted complete instrument type and serial number and a description of the service required If the original packaging is unfit for use or not available package the instrument as follows 1 Obtain a corrugated cardboard shipping carton with a 375 pound test strength and having inside dimensions at least six inches greater than the instrument dimensions 2 Surround the instrument with antistatic polyethylene sheeting or equivalent to protect the finish of the instrument 3 Cushion the instrument on all sides by tightly packing dunnage or urethane foam between the carton and the instrument allowing three inches on each side 4 Seal the carton with shipping tape or with an industrial stapler 5 Mark the address of the Tektronix Service Center and your return address on the carton in one or more prominent locations 1 3 General Informa
134. before the individual circuits are discussed in detail A basic block diagram of the 7904A is shown in Figure 3 1 Only the basic interconnections between the individual blocks are shown on this diagram Each major circuit within the instrument is given a block The number of each block refers to the complete circuit diagram located at the rear of this manual DESCRIPTION Vertical signals to be displayed on the crt are applied to the Vertical Channel Switch circuit from both vertical plug in compartments The VERTICAL MODE switch is connected to the logic circuit and determines whether the signai from ihe LEFT VEHT or RIGHT VERT compartment is displayed on the crt The Vertical Channel Switch receives an X Y inhibit signal from the Readout system to provide the time sharing between the vertical and readout signals The selected vertical signal passes through the Delay Line and is amplified by the Vertical Amplifier circuit to drive the vertical deflection plates of the crt cathode ray tube The Vertical Amplifier circuit includes an input from the Readout System to produce the verticali portion of the alpha numeric readout display Horizontal signals for display on the crt are connected to the Horizontal Channel Switch from both horizontal plug in compartments The HORIZONTAL MODE switch determines whether the signal from the A HORIZ or B HORIZ compartment is displayed by the crt The signal from A amp B HORIZ plug in compartments may p
135. board illustrations in Section 8 Diagrams and Circuit Board lllustrations A7T A8 A9 A10 A25 A26 Follower Circuit Boards Foliower circuit boards with four or six interface contacts are used in the plug in interface connectors to provide optimum signal connections between the plug in units and the 7904A Each Follower board is held in place by a spring so that the board can move back and forth within the interface connector to compensate for Maintenance 7904A length differences between plug in units a contact on a Follower board is damaged the entire board with contacts and interconnecting cables is replaced as a unit Remove a Follower circuit board as follows 1 Disconnect the instrument from the power source and remove any plug in units 2 Remove the power supply unit see Power Supply Unit Removal 3 Remove the metal shields in front of the A6 Main interface board 4 Disconnect the coaxial leads of the Follower board from the A16 Vertical Channel Switch board A29 Horizontal Interface or A14 Trigger Selector board Note the location of the connectors so they may be correctly replaced 5 Using long nose pliers disengage the spring from the Follower board spring is in front of A6 Main Interface board 6 Remove the Follower board with interconnecting cables from the rear of the interface connector through the hole in the A6 Main Interface board To replace a Follower circuit board a folded length of
136. check the electrical characteristics of the instrument Procedures are also provided for adjustment of the instrument to meet specifications Section 6 Instrument Options contains a description of available options and locations of incorporated information for those options Section 7 Replaceable Electrical Parts contains information necessary to order replaceable parts and assemblies related to the electrical functions of the instrument Section 8 Diagrams and Circuit Board Illustrations includes detailed circuit schematics locations of assembled boards within the instrument voltage and waveform information circuit board component locators and locations of adjustments to aid in performing the Checks and Adjustment section of this manual Section 9 Replaceable Mechanical Parts includes information necessary to order replaceable mechanical parts and shows exploded drawings which identify assemblies INSTALLATION INITIAL INSPECTION This instrument was inspected both mechanically and electrically before shipment it should be free of mars or scratches and meet or exceed ail electrical specifications To confirm this inspect the instrument for physical damage incurred in transit and test the electrical performance by following the Operating Checkout Procedure in Section 2 Operating instructions Verify Performance Requirements by referring a qualified service person to the servicing sections of the instruction Man
137. circuit board and in the schematic diagrams ADJUSTMENT AND TEST POINT LOCATIONS To aid in locating test points and adjustable components called out in the various sections of the Checks and Adjustments procedures the Adjustment and Test Point Locations pullout pages are provided in the rear of Section 8 Diagrams and Circuit Board Hiustrations COMPONENT COLOR CODING The instrument contains carbon composition resistors metal film resistors and wire wound resistors The resistance values of wire wound resistors are usually printed on the component body The resistance values of composition resistors and metal film resistors are color coded on the components using the EIA color code some metai film resistors may have the value printed on the body The color code is read starting with the stripe nearest the end of the resistor Composition resistors have four stripes which consist of two significant figures a multiplier and a tolerance value see Fig 4 1 Metal film resistors have five stripes consisting of three significant figures a multiplier and a tolerance value The values of common disc capacitors and small electrolytics are marked on the side of the component body The white ceramic capacitors used in the instrument are color coded using a modified EIA code see Fig 4 1 The cathode end of glass encased diodes is indicated by a stripe a series of stripes or a dot see Fig 4 2 The cathode and anode ends of m
138. compensation READOUT SYSTEM SN B031766 amp Below schematic diagram of the Readout System is given on Diagram 6 in Section 8 of this manual Diagrams and Circuit Board lilustrations This schematic is divided by gray shaded lines separating the circuitry into major Stages These stages aid in locating components mentioned here Stage name headings in the following discussion are used to further identify portions of the circuitry on Diagram 6 The Readout System provides an alphanumeric display of information encoded by the plug in units This display is presented on the crt and is written by the crt beam on a time shared basis with the analog waveform display The following terms are used to describe the Readout System Character A single number letter symbol displayed on the crt either alone or in combination with other characters Word A group of related characters the Readout System a word can consist of up to 10 characters Frame A dispiay of all words for a given operating mode and plug in combination Up to 8 words can be displayed in one frame Figure 3 8 shows the position of each word in a complete frame Column One of the vertical lines in the Character Selection Matrix see Fig 3 9 Columns C O column zero through C 10 column 10 can be addressed by the system REV NOV 1985 Theory of Operation 7904A Row One of the horizontal lines in the Character Selection matrix Ro
139. composite current wave form of Figure 3 24B the relative phase and amplitude of each component of is shown for periods T T and T corresponding to the three switch positions Figure 3 24C and Figure 3 24D show the relationship of the Inverter voit age and primary winding voltages with respect to the cur rent waveform The normal sequence of operation is as follows assume that the voltage at point X is some voltage more positive than the negative supply voltage and that 040 has just turned on The current labeled in Figures 3 24A and 3 24B flows as the voltage at point W goes negative Point X goes toward the supply voltage as C37 charges through L37 The voltage across the primaries of T110 and T35 at point Y produces a voltage at the secondary of T35 that is sensed by the Inverter Control U75 see Fig 3 24D When this voltage changes phase from negative to positive Q40 is held off turned off by U75 Due to the inductive action of L37 current continues to flow through the Inverter circuit pulling the voltage at point W below the negative supply voltage This forward biases 41 which now conducts Figures 3 24A and 3 24B After a predetermined time the Inverter Control iC U75 allows Q34 to turn on and conduct the current labeled 12 in Figures 3 24A and 3 24B Since Q34 is now conducting the voltage at point X charges toward the positive supply voltage through L37 Once again voltage phase cha
140. crt along with the analog waveform display The information displayed by the Readout System is obtained from the plug in units installed in the plug in compartments The readout information from each channel of the plug in units is called a word Up to eight words of readout information can be displayed on the crt two channels from each of the four plug in compartments The location of each readout word is fixed and is directly related to the plug in unit and channel from which it originated Figure 2 4 shows the area of the graticule where the readout from each plug in unit and or channel is displayed Notice that the readout from channel 1 of each plug in unit is displayed in the top division of the graticule and the readout from channel 2 is displayed directly below in the bottom division of the graticule Usually the readout information for plug in units and or channels which are selected by the mode switches appears in the readout display Some special purpose plug in units may over ride the mode switches to display readout even though the compartment is not selected for display Readout identify An Identify feature is provided by the Readout System to correlate the readout word with the originating plug in unit and channel amplifier units only When the Identify button of an amplifier unit is pressed the word IDENTIFY appears in the readout location alocated to that plug in and channel Other readout words in the displa
141. d of this step within 0 08 division 0 ADJUST if necessary compromise the setting of R230 on the A28 Horizontal Amplifier Board for optimum gain in both horizontal compartments If readjustment is necessary repeat parts a b c and d of this step 5 56 5 ADJUST READOUT CENTERING AND GAIN A28R114 A28R101 NOTE If the preceding step was not performed first perform step E1 then proceed ES SETUP CONDITIONS 7904A Controls No change in settings Test Equipment Controis No equipment necessary 4593 531 Set the 7904A POWER switch to OFF Remove Q2225 from its socket on the A15 Readout Systems Board see Test Point and Adjustment Locations G Set the 7904A POWER switch to ON and adjust the READOUT INTENSITY control for visible characters all zeros EXAMINE the crt display for two rows of zeros centered horizontally within the graticule area See Figure 5 2 Checks and Adjustment 7904A Part and Performance Check 0000 00000005000 0000000000000 000 0000000 E FUSE DEAS RUN QOOOOOOGOGDODDOOOOOGU Sly a 1676 5 Figure 5 2 Readout display with 02225 removed ADJUST RO CENTER adjustment R114 on the A28 Horizontal Amplifier Board to horizontally center the readout display within the limits of the graticule area ADJUST RO Gain adjustmen
142. discharged by shorting the anode lead from the crt to the chassis Wait approximately ten minutes and again firmly short this lead to the chassis Then remove the crt Use care when handling a crt Breakage of the crt causes a high velocity scattering of glass fragments Protective clothing and safety glasses should be worn Avoid striking the crt on any object which might cause it to crack or implode When storing a crt place it in a protective carton or set it face down in a protected location on a smooth surface with a soft mat under the faceplate Remove the crt base pin socket from the rear of the crt Loosen the two screws located above and below the crt base pins until the tension of the springs on these screws is released access to the 2 screws is through holes in the A20 High Voltage board Then press in upon the screws to be certain that the crt clamp inside the crt shield is loose Disconnect the two vertical deflection plate connectors The vertical deflection plate connections are from the A18 Vertical Amplifier board by way of the A31 Vertical Flexcon connector Disconnect the two horizontal deflection plate connectors from the top of the crt Disconnect the two vertical termination connectors from the crt located directly in front of the vertical deflection plate connectors Remove the plastic and metal masks which cover the crt bezel Remove the four sc
143. display for a gate waveform 5 divisions in amplitude within 10 and a baseline at zero voits within one volt b Move the time base unit to the HORIZ compartment c Set the GATE selector switch to the B position d test oscilloscope display for a gate waveform 5 divisions in amplitude within 10 and a baseline at zero volts within one volt 5 19 Checks and Adjustment 7904A Part Check B7 CHECK GRATICULE ILLUMINATION a CHECK that rotating the GRAT ILLUM control OPERATION throughout its range varies the illumination of the NOTE graticule If the preceding step was not performed first b Set the GRAT ILLUM contro fully clockwise to the perform step B1 then proceed PULSED detent position B7 SETUP SONDNIONS D Set the A INTENSITY control for a visible display E TEREE d CHECK that graticule illumination occurs only GATE A or B Switch after the time base has completed a sweep adjust HORIZONTAL MODE ILLUM PRESET if necessary Setthe GRAT ILLUM GATE or EXT switch to EXT t CHECK that pressing the GRAT ILLUM pushbutton causes one momentary illumination of the graticule g Set the GRAT ILLUM control to midrange out of the PULSED detent position v s Test Equipment Controls Time Base Sweep Hate isco cre 0 2 s div Triggering Auto AC Internal 4593 416
144. div Vertical Deflection Vertical Mode Channel 1 Time Base Sweep 0 1 ms div Triggering 4593 414 a Connect the SAWTOOTH output connector to the test oscilloscope channel 1 vertical input one megohm input b CHECK that the slope of the test oscilloscope display rises 2 volts horizontal division within 1096 10 volt sawtooth for 5 division sweep on test oscilloscope screen and that the sawtooth baseline is within one voit of ground c Move the time base to the 7904A B HORIZ compartment d Set the SAWTOOTH selector switch to the B position e CHECK the test oscilloscope display for 2 volts division of sweep within 10 10 volt sawtooth for 5 division sweep on the 7904A crt screen and that the sawtooth baseline is within one volt of ground Checks and Adjusiment 7904A Part i Performance Check B6 CHECK A AND B GATE OUTPUT SIGNALS NOTE If the preceding step was not performed first perform step B1 then proceed B6 SETUP CONDITIONS 7904A Controls GATE A or B Switch Test Oscilloscope o a m Coaxial Cable Test Equipment Controls Test Oscilloscope Vertical Deflection Factor Sweep Rate 0 2 ms div Time Base Auto AC Internal Sweep Rate 0 1 ms div 4593 415 S a test oscilloscope
145. during the positive and negative half cycles of the input square wave respectively to limit the square wave amplitude at their junction Grid Bias adjustment R65 sets the voltage on the cathode of CR64 to establish the forward bias level and peak positive level at the anode of CR64 The dc level of the Z Axis Amplifier output determines the voltage on the anode of CR63 which establishes the forward bias level and peak negative level at the cathode of CR63 The limited amplitude square wave at the junction of CR64 and CR63 is coupled to the junction of CR67 and CR68 through C66 During the positive half cycle CR67 is forward biased to clamp its anode at the crt cathode voHage level During the negative haif cycle C69 is charged through CR68 to a voltage level more negative than the crt cathode The amount of charge is equal to the difference between the Grid Bias adjustment setting and the Z Axis Amplifier output level High frequency 2 Axis Amplifier signals are coupled to the control grid through C72 R72 R63 and C69 FOCUS GRID DC RESTORER The operation of the Focus Grid DC Restorer is similar to the operation of the Control Grid DC Restorer The limited amplitude square wave at the junction of CR34 and CR33 is coupled to the junction of CR38 and CR37 through C36 The amplitude of the positive half cycie of the input square wave is clamped at approximately 130 volts by CR34 The peak negative amplitude is established by the dc leve
146. in Unit Performance Feature 7112 7114 7118 7 11 7 13 7511 7512 Applications 7514 Dual Trace Delay Sweep Sampler MODEM MNT QM MM DUE QC TM O S 100 kHz to 1 7 GHz Spectrum Analyzer 10 kHz to 1 8 GHz Spectrum Analyzer 1 5 GHz to 60 GHz Spectrum Analyzer Dual 500 Delay Line Readout Access Unit Accepts Plug In Sampling Heads Time Domain Reflectometer and Sampling Random or Sequential equivalent or Heal Time Sampling General Information 7904A STANDARD ACCESSORIES The following accessories are furnished with your 7904A Oscilloscope For more detailed information refer to the tabbed Accessories page at the rear of this manual dis osse eta c PM Instruction Manual HE Pc T Blue Faceplate Filter installed lt oP OPTIONAL ACCESSORIES not included The following accessory is available for use with your 7904A Oscilloscope For more detailed information refer to the tabbed Accessories page at the rear of this manual Order Optional Accessories through your local Tektronix Field Office or representative Current Loop Probe Adapter 1 15 Section 2 7904A OPERATING INSTRUCTIONS To operate the 7904A effectively the user must become familiar with the ope
147. level of graticule activates PULSED GRAF ILLUM SIG OUT Connector to output signal derived from vertical signal as selected by B TRIGGER SOURCE switch GRAT ILLUM PRESET Screwdriver adjustment to vary level of graticule illumination in GRAT ILLUM PULSED mode ASTIG Screwdriver adjustment used in conjunction with FOCUS control to obtain a well defined display GRAT ILLUM GATE OR EXT Switch to select between GATE or EXT actuation of graticule illumination B TRIGGER SOURCE Switches select internal trigger source for B HORIZ plug in unit Ground not labeled Binding post to establish common ground between associated equipment GRAT ILLUM MAN Switch when pressed actuates one graticule illumination VERT TRACE SEPERATION 8 Control vertically positions the B HORIZ trace with respect to the A HORIZ trace dual sweep only TRACE ROTATION Screwdriver adjustment to align trace s with graticule lines HORIZONTAL MODE Switches select input source for horizontal deflection VERTICAL MODE Switches select source of input for vertical deflection POWER Swiich and indicator Switch controis power to instrument indicator illuminates when power is on CALIBRATOR Switches select 4 V 0 4 V and 40 mV calibrated square wave voltages at 1 kHz repetition rate at connector output A TRIGGER SOURCE Switches select internal trigger source for A HORIZ pilug in unit 4593 228 Figure 2 1 cont
148. negative shift of the DC current level The DC current level is coupled to the inverting input of operational amplifier 01952 and converted to a positive voltage at the noninverting input of Operational amplifier U1958 This causes the output of U1958 to go positive which turns on emitter follower Q1956 and produces a positive Intensity Reference output at TP1958 When the Intensity Reference goes positive diodes 2009 and CR2019 in the INTENSITY control circuit diagram 2 will conduct to cause intensity limiting through the Z AXIS Logic circuit diagram 4 and the Auto Focus circuit diagram 12 VERTICAL CHANNEL SWITCH The Vertical Channel Switch circuit selects the vertical deflection signal from the output of the LEFT and or RIGHT VERT plug in compartment s for display on the crt A schematic diagram of the Vertical Channel Switch is given on diagram 8 in Section 8 of this manual Diagrams and Circuit Board Hlustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use the stage names to further identify portions of the circuitry on diagram 8 3 52 CHANNEL SWITCH The vertical deflection signal from the left and right vertical plug in units is either terminated within the stage or coupled through the stage as determined by the Vertical Channel Selector stage The Channel Swit
149. negative than about zero volts Negative going pulse at two megahertz rate 5 can be and not affect operation if pin 8 is LO and vice versa with the switching between the displayed traces The duty cycle of the wide pulse train produced in the clock generator stage determines the pulse width of the Vertical Chopped Blanking pulses CHOP COUNTER The Chop Counter stage U4340 produces the Vertical Chopped signal the Plug in Chop Command and the To CLOCK PIN 15 Horizontal Chopped Blanking signal The clock pulse produced by the clock generator stage provides the timing signal for the Chop Counter The functions of the input and output pins for the Chop Counter IC U4340 are identified in Figure 3 5 Idealized waveforms showing the timing relationship between the input and output signals for this stage are shown in Figure 3 5B DELAY PIN 10 N N N VERTICAL CHOPPED BLANKING PIN 4 MS DELAY 1195 18 2314 3 Figure 3 4 idealized waveforms for the Vertical Chopped Blanking U4320 3 17 Theory of 7904 CHOP MODE HORIZ CLOCK CLOCK PIN 10 i VERTICAL CHOPPING SIGNAL PIN 1 PLUG IN CHOP COMMAND PIN 8 CHOP MODE 2 PIN 5 l l HORIZONTAL CHOPPED BLANKING PIN 4 VERTICAL CHOPPED BLANKING PIN 4 943208 8 VERTICAL CHOPPING SIGNAL HORIZONTAL CHOPPED BLANKING PLUG IN
150. on the screws are fully compressed 6 Place the crt base pin socket on the crt base pins 7 Carefully reconnect the ert neck pin connectors 8 Reconnect the crt anode plug 9 Replace the plastic crt bezel mask NOTE The replacement of the crt will require that the instrument be re adjusted Refer to Section 5 Checks and Adjustment CIRCUIT BOARDS If a circuit board is damaged beyond repair repiace the entire board assembly Part numbers are given in Section 7 Replaceable Electrical Parts for completely wired boards Most of the circuit boards in this instrument are mounted on the chassis pin connectors are used for electrical interconnection with chassis mounted components and other circuit boards Several boards plug onto the rear of the A6 Main Interface board feed thru connectors connect the plug on boards to the 6 Main Interface board Chassis Mounted Boards Remove and replace ali chassis mounted circuit boards as follows 4 18 i Disconnect pin connectors attached to the board or which connect the board to other parts of the instrument 2 Hemove the securing screws 3 Remove the chassis mounted board 4 Replace chassis mounted boards in the reverse order of removal Match the index arrow on the multi pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown on the circuit board illustration in Section 8 Diagrams and Circuit Board Illustrations
151. physical specification of the 7904A list compatibility information for plug in units and provide a list of standard and recommended accessories TECHNICAL MANUALS An instruction manual is shipped as a standard accessory to the 7904A Oscilloscope INSTRUCTION MANUAL The 7904A Instruction Manual contains the information necessary to operate and service your instrument The content of the instruction manual is described as follows Section 1 General Information contains instrument description electrical specifications environmental characteristics standard and optional accessories installation and packaging for shipment instructions Section 2 Operating Instructions contains information relative to operating and checking the instrument operation THE FOLLOWING SERVICING INSTRUC TIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY TO AVOID PERSONAL INJURY DO NOT PERFORM ANY SERVICING OTHER THAN THAT CONTAINED IN OPERATING INSTRUC TIONS UNLESS YOU ARE QUALIFIED TO DO SO REFER TO OPERATORS AND SERVICING SAFETY SUMMARIES PRIOR TO PERFORMING ANY SERVICE Section 3 Theory of Operation contains basic and general circuit analysis that may be useful for servicing or operating the instrument Section 4 Maintenance describes routine and corrective maintenance procedures with detailed instructions for replacing assemblies subassemblies and individual components Section 5 Checks and Adjustment contains procedures to
152. pin 11 by the oscillator output from Q2153 Q2204 will be considered to be part of the Character Gen erator in the discussion that follows VERTICAL OCTAL ADDRESS HEXIDECIMAL BINARY 87654321 00000000 00001000 01111000 01001000 01111000 00001100 01100000 01111100 01100000 01001100 10000000 CHARACTER GENERATOR OUTPUT BIT 7 Theory of Operation 7904A The Character Generator U2203 is a 4k X 8 bit EPROM which contains the binary words used by the output stages in creating the signals necessary to form readout charac ters There are twelve address inputs with the lower four coming from the Lower Order Address Generator the cen ter four from the Column Decimal to BCD Converter and the upper four from the Row Decimal to BCD Converter As previously mentioned each character is developed on an 8 point by 8 point grid see Fig 3 22 for a typical character The Character Generator s 8 bit output provides the in formation necessary to move the instrument beam around within the grid to turn the beam on and off and to indicate when a character is complete BIT 8 END OF CHARACTER MOVE DRAW Figure 3 22 Developing a typical character on the CRT SN B031767 amp Above REV NOV 1985 3 49 Theory of Operation 7904A The row and column data cause a 4 bit binary code to be generated at
153. pins 9 12 and 15 of the Character Generator latch U2204 The digital highs and lows across R2206 R2207 and R2208 are mixed as stepped current levels at pin 2 of U2210A These sudden analog steps are converted into a smooth transition from one level to the next by RCL network R2212 C2212 and L2212 U2210B current buffers the resulting signal to be mixed with the Channel Counter vertical information at the input of the Y Output Amplifier The X Vector Generator operates similarly to the Y Vector Generator Gain for the stage is fixed by the circuit compo nents and its output is current buffered to be mixed at the input of the X Output Amplifier OUTPUT AMPLIFIERS The Y Output Amplifier provides the Y vertical signal to the instrument by combining the signal from the Y Vector Gen erator with the channel 1 or 2 information from the Channel Counter The amplifier consists of U2257B with Q2255 in its input circuit Amplifier gain is adjustable with R2260 to con troi the vertical separation between readout words dis played at the top and bottom of the graticule area 02255 switches the amplifier input on and off with the Timer Ready signal using Q2250 to provide impedance matching The channel 1 or 2 information from pin 3 of the Channel Counter U2127A is inverted by U2251A and converted to current by R2252 and R2253 The Channel Counter pro duces a LO at pin 3 when the readout word is to be dis played at the top of the graticule
154. plug two pole three terminal grounding type This instrument is safety class 1 equipment IEC designation All accessible conductive parts are directly connected through the grounding conductor of the power cord to the grounding contact of the power plug Therefore the power plug must only be inserted in a mating receptacle with a grounding contact Do not defeat the grounding connection Any interruption of the grounding connection can create an electric shock hazard For electr c shock protection the grounding connection must be made before making connection to the instrument input or output terminals tnternational Electrotechnical Commission OPERATING TEMPERATURE The 7904A can be operated where the ambient air temperature is between 0 and 50 C and can be stored in ambient temperatures from 559 to 75 After storage at temperatures outside the operating limits allow the chassis temperature to reach a safe operating limit before applying power The 7904A is cooled by air drawn in through holes in the top side and bottom panels and blown out through the fan exhaust To ensure proper cooling of the instrument maintain the clearance provided by the feet on the bottom and allow at least 2 inches clearance more if possible at the top sides and rear of the instrument General Information 7904A OPERATING POSITION A bail type stand mounted on the bottom of the instrument permits the instrument to
155. resultant crt readout will be o 100 uV the above example the row analog data was programmed to define which row of the Character Selection Matrix was addressed to obtain information in each time slot The column data changes to encode the applicable readout data as the operating conditions change For example if the variable control of the plug in unit was activated R130 would be connected between time siot 3 and the column analog data output line This encodes 10 units of column current see shaded area in time siot 3 of the waveform shown in Fig 3 16 Since one unit of row current is also encoded during this time siot by R30 a greater than symbol is added to the display The crt readout will now show gt 100 In a similar manner the other switches can change the encoded data for the column output and thereby change the readout display See the descriptions which follow for decoding this information 3 32 The column analog data encoded by most plug in units can be modified by attenuator probes connected to the input connectors of amplifier plug in units A special coding ring around the input connector of the plug in unit senses the attenuation ratio of the probe with readout encoded probes only The probe contains a circuit that provides additional column current For example if a 10X attenuator probe is connected to a plug in unit encoded for 100 microvolts as shown Figure 3 15 an additional unit of cur
156. single j sweep operation 7885 set for singie sweep operation with A time function operational Time base unit set for alternate and single sweep modes 715 7 5 set for single scan operation i Only one time base unit eee a a a e e e ETT SE E Pulsed readout and pulsed graticule from gate source do not operate normaily Pulsed readout and pulsed graticule from gate source do not operate normally Pulsed readout and puised graticule from gate source do not operate normally 71 13 set for single sweep 71 13 will not start by remote operation or camera connection 7904A alternate sweep switching logic locks out one time base unit these time base units do not reset when locked out 7885 sweeps once but needs to sweep twice for generation of hoidoff pulse Time base unit sweeps only once when reset whereas both main and delay sweep are required to generate a holdoff pulse 715 Sweep Gate remains 7L13 does not provide single sweep reset General Information 7904A TABLE 1 6 CONT Plug In incompatibilities Plug in Operating Symptoms Cause Unit i Conditions 7512 7512 set for single scan 7812 will not start by remote 7512 does not provide single operation or camera reset connector sweep reset All 7812 will not alternate with 7512 does not generate holdoff other sweep plug ins pulses Intensified zone The inte
157. standardizer Amplitude control for a six division display centered on the graticule The CW Leveled indicator should be lit Without changing the output amplitude increase the generator frequency until the displayed amplitude is reduced to 4 6 divisions If the CW Leveled indicator extinguishes increase the amplitude of the sine wave generator signal unti the light just turns on 5 27 Checks and Adjustment 7904A Part i Performance Check NOTE E5 CHECK VERTICAL CHANNEL ISOLATION The signal standardizer CW Leveled light NOTE must be on and the sine wave generator must be properly connected for a valid check Refer to the signal standardizer and high frequency sine wave generator manuals If the preceding step was not performed first perform step E1 then proceed E5 SETUP CONDITIONS 7904A Controls e CHECK sine wave generator frequency is 500 MHz VERTICAL MODE or higher verifies 500 megahertz gain f Move the signal standardizer to the LEFT VERT compartment leave signal connected and set the VERTICAL MODE switch to LEFT High Frequenc Sine W 0 CHECK repeat parts d through f for the LEFT VERT compartment amp hl sls a 41 Coaxial Cable Test Equipment Controls Time Base Sweep Rate 1 ms div Triggering Auto AC Internal Amplifier input Coupling High Frequency Sine Wave Generator 4593 425 a Connect the output of the high frequency sine wave
158. sweep chops between horizontal units B B horizontal unit only M M Phase Shift Between 2 or less from dc to 04 Check X Y Delay Check Adjust X Y Delay Vertical and Horizontal at least 35 kHz Compensation Comnpensation Systems With Option 2 2 or less from dc to 1 MHz E PETENDUM RON CALIBRATOR Wave Shape Square wave B4 Check Calibrator Rise C4 Check Calibrator Ris Time Fall Time and Duty Time Fall Time and Duty Cycle Cycle Polarity Positive going with base B2 Check Calibrator Output C2 Check Adjust Calibrator line at Volt Voltage Output Voltage Output Voltage Selected by front panel CALIBRATOR switch into 2100 40 mV 0 4 V 4 V Into 50 2 4 mV 40 mV 0 4 V 5 5 Checks Adjusiment 7904A Characteristics TABLE 5 2 CONT Performance Check Summary Pari i Performance Check equiremen Procedure Title Part H Adjustment and Performance Check Output Current Amplitude Accuracy P P Voltage Repetition Rate Duty Cycle CALIBRATOR CONT _ Procedure Title rrr a 40 mA available through i Does not normally require customer verification CALIBRATOR output with optional bnc to current ioop adapter CALIBRATOR switch must be set to 4 V for calibrated output Within 1 B2 Check Calibrator Output i Voltage s l 83 Check Calib
159. than 1 nanosecond The technique used for sampling is very similar in principle to the use of stroboscopic light to study fast motion Samples of successive waveforms are taken amplified by a relatively low bandwidth amplifier and then displayed on the crt as a replica of the sampled waveforms Three sampling systems are available at this time for the 7904A 1 the 7812 which provides time domain reflectometry displays and general purpose sampling measurements 2 the 7511 7 711 system and 3 the 7814 a dual channel vertical sampling system 2 16 including main and delayed sweep functions See the Tektronix Products catalog to determine the characteristics of individual units mentioned and of additional units made available after this manual is published Single Trace Sampling A single trace sampling display requires either a double width 7512 which includes a time base or the 7511 sampling unit and the 7T11 sampling sweep unit Direct interconnections between the 7511 and the 7T11 require these units to be adjacent with the 7511 in the RIGHT VEHT compartment and the 7T11 in the A HORIZ compartment If either the 7512 or the 7814 is used it must be located in the middie two compartments to make proper connections with the 7904A Dual Trace Sampiing Two 7811 s can be used with a single sampling time base unit for time related displays of two signals Direct interconnections from the the LEFT VERT 7511 pas
160. the 7 5 volts at pin 6 The 2 volt nominal supply connected to pin 7 is unregulated Zener diode VR72 provides protection against open circuit conduction 075 removed and is normally not conducting Pin 15 is the voltage sensing E Sense point of the pre regulator circuit Zero volts at pin 15 indicates proper regulation Zener diode 88 provides a stable reference voltage for sensing divider resistors R93 R95 R86 and 87 Variable resistor R93 in this divider adjusts the ratio of the divider to adjust the output of the 108 voit supply Outputs of the other supplies are then set by the turns ratio of T110 3 62 Integrated circuit U75 regulates the Inverter by varying the hoid off time of the switching transistors Q34 and Q40 A variable pulse width monostable multivibrator in 075 is triggered at pins 10 and 11 whenever the Inverter current changes direction The pulse width holds off the Inverter by turning on transistor Q52 through pin 9 of 175 thus shorting the base drive to Q34 and 040 The pulse width and therefore holdoff is controlled by a ramp at pin 12 If the voltage at the E Sense input pin 15 is too low the ramp is not allowed to rise very high and the pulse width and holdoff are short As the E Sense voltage rises the ramp is allowed to rise to a higher voltage level increasing the hoidoff time Fault Protection The fauit protection portions of U75 provide protection for the power supply componen
161. the 10 to 9096 points of the waveform rise time 0 5 microsecond less Set the test oscilloscope for a stable display triggered on the negative transition of the waveform CHECK the displayed waveform for not more than 5 divisions between the 90 and 10 amplitude points fall time 0 5 microsecond or less Set the test oscilloscope triggering for positive slope and auto mode with ac coupling from the internal source at a sweep rate of 0 1 millisecond division Set the triggering controls so that the display starts at the 5096 point on the rising edge of the waveform Set the test oscilloscope sweep magnifier to X10 Then position the display horizontally so the falling edge of the waveform aligns with the center vertical graticule line Set the test oscilloscope vertical to invert the display NOTE The display is triggered on the opposite Slope even through the display appears the same CHECK that the 50 point on the falling edge of the waveform now displayed is within 0 2 divisions horizontally of the center line Indicates duty cycle of 5096 within 0 296 85 CHECK AND SAWTOOTH OUTPUT SIGNALS NOTE If the preceding step was not performed first perform step B1 then proceed B5 SETUP CONDITIONS 7904A Controls SAWTOOTH A or B Switch SAWTOOTH Connector Test Oscilloscope o o Coaxial Cable Test Equipment Controls Test Oscilloscope Sweep Rate 2 ms
162. the RIGHT VERT unit is to be displayed For the CHOP position of the VERTICAL MODE switch a HI level is applied to the anodes of CR4323 CR4322 through R4322 Both diodes are forward biased so that the Vertical Chopping Signai from pin 1 of U4340 can pass to the base of 04382 This signal switches between the HI and LO levels at a one megahertz rate and produces a corresponding Display Right Command output at the collector of Q4392 When the Display Right Command is HI the RIGHT VERT unit is displayed When it switches to LO the LEFT VERT unH is displayed In the ALT position of the VERTICAL MODE switch a HI level is applied to the anodes of CR4369 CR4368 through R4369 These diodes are forward biased so the Vertical Alternate Command from pin 6 of the Vertical Binary stage can pass to the base of Q4382 to determine the Vertical Mode Command level The Vertical Alternate Command switches between its Hi and LO levels at a rate determined by the Vertical Binary stage The control levels in the LEFT and ADD positions of the VERTICAL MODE switch are not connected to this stage However since only the line corresponding to the selected vertical mode can be HI the RIGHT CHOP and ALT lines must remain at their LO level when either LEFT or ADD are selected Therefore the base of Q4382 remains LO to produce a LO Display Right Command signal output level at the collector of Q4392 A logic diagram of the Vertical Mode Logic stage is shown in
163. the operating power for this instrument from an ac line voltage source This circuit inciudes a LINE VOLTAGE SELECTOR switch located on the rear panel Figure 3 20 shows a detailed block of the Converter Rectifiers circuit A schematic diagram of the Converter Rectifiers is given on diagram 14 in Section 8 Diagrams and Circuit Board Hlustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stage names aid in locating and identifying the components and portions of circuitry mentioned here LINE INPUT Power is applied through line filter FL10 line fuse F10 and POWER switch S10 The line filter is designed to INVERTER START VR38 030 LINE SELECTOR i LINE INPUT 3 CR15 E8 E13 LINE FILTER FLIO LINE LINE TRIGGER TO PLUG IN COMPARTMENTS INVERTER Theory of Operation 7904A keep powerline interference from entering the instrument and to keep the approximate 25 kilohertz Inverter signal from entering the power line Components R5 C5 and C6 suppress reverse recovery transients of CR15 The LINE VOLTAGE SELECTOR switch 12 allows the instrument to operate from either a 115 volt nominal ora 230 volt nominal line voltage source In the 115 volt position rectifier CR15 operates as a full wave doubler with energy storage capacitors C16 and C17 so the voltage across the two capacitors in series will be the approximate peak to peak value of t
164. the time base units in the A HORIZ and B HORIZ compartments Correct triggering of both time base units is essential in obtaining the correct display in the ALT horizontal mode If either of the time base units does not receive a correct trigger and therefore does not produce a sweep the other unit cannot produce a sweep either This means that one time base unit cannot begin its sweep until the previous unit has completed its entire display This can be avoided if the time base units are set for auto mode triggering sweep free runs if not correctly triggered See Trigger Source for operation of the A and B TRIGGER SOURCE switches Also see Vertical Trace Separation for information on positioning the B HORIZ display when in the ALT dual sweep mode Chopped Mode When the CHOP button of the HORIZONTAL MODE switch is pressed the display is electronically switched between the two time base units at about a 200 kilohertz rate In general the CHOP horizontal mode provides the best display when either of the time base units is set to a sweep rate lower than about 20 milliseconds division It also provides the best display when the two time base units are set to widely differing sweep rates In the CHOP horizontal mode equal time segments are displayed from each of the time base units This provides a display which does not change greatly in intensity as the sweep rate of either time base unit is reduced in contrast to ALT HORIZONTAL
165. time base unit and sawtooth output portion of the Output Signals circuit is operating correctly If a malfunction in the Readout System is suspected of causing trouble to appear in the Z Axis Amplifier Vertical Amplifier or Horizontal Amplifier circuits the trouble can be localized by removing the Readout System circuit board This board can be removed without significantly affecting the operation of other circuits in the instrument 4 7 Maintenance 7S804A incorrect operation of all circuits often indicates trouble in the power supply Check first for correct voltage of the individual supplies However a defective component elsewhere in the instrument can appear as a power supply trouble and may also affect the operation of other circuits If incorrect operation of the power supplies is suspected refer to Troubleshooting the High Efficiency Power Supply Unit given later in this section 6 CHECK VOLTAGES AND WAVEFORMS Often the defective component can be located by checking for the correct voltages or waveforms in the circuit Typical voltages and waveforms are given in Section 8 Diagrams and Circuit Board Hlustrations NOTE Voltages and waveforms given in Section 8 Diagrams and Circuit Board Illustrations are not absolute and may vary slightly between 7904A Oscilloscope mainframes To obtain operating conditions similar to those used to take these readings see the appropriate schematic 7 CHECK INDIVIDUAL COMPON
166. to CHOP Four traces should be displayed on the crt If not adjust the position controls of the amplifier units and the VERT TRACE SEPARATION B control to position 28 29 the four traces into view Set the position controls of the plug in units to identify which trace is produced from each plug in unit if amplifier units have the identify feature it can be used to identify the traces Set the A time base unit for a sweep rate of 1 millisecond division Notice that there are two displays from the left vertical unit one at the sweep rate of the A time base unit and the other at the sweep rate of the B time base unit Notice also that there are two displays from the right vertical unit again one at the sweep rate of the A time base unit and the other at the sweep rate of the B time base unit Set the HORIZONTAL MODE switch to ALT Observe that the display is very similar to that obtained in the previous sweep The main difference in this display is that the traces are now displayed alternately noticeable only at slow sweep rates Set the VERTICAL MODE switch to ALT The trace produced by the left amplifier unit should be displayed at the sweep rate of the B time base unit and the trace produced by the right amplifier unit should be displayed at the A time base unit sweep rate This feature is called slaved alternate operation and is obtained only when the VERTICAL MODE switch is in the ALT position the HORIZONTAL MODE switc
167. two screws securing A12C154 and remove the metal cased capacitor from the circuit board 4 Remove 4 screws securing the transformer to the mounting bracket and remove the transformer 5 Place the new transformer in position and solder the leads to the 12 Rectifier circuit board pads 6 Attach the transformer to the bracket with 4 screws 7 Secure the metal cased capacitor to the 12 Control Rectifier board with 2 screws Maintenance 7904A 6 INCH STEEL RULE OR EQUIVALENT RIGHT BOTH ENDS OF CONTACT ARE FREE OF THE CARRIER o Make sure that all switch shafts are in the OUT position to clear the rear clip Piace the long edge of a six inch rule or similar thin straight edge between the top edge of the rear clip and the switch body Carefully pry the rear clip back just far enough to push the steel rule down between the clip and switch body CAUTION When the switch is removed the contacts may drop free and be damaged or lost Body salts or acids can contaminate the switch contacts Wear cotton gloves to prevent touching the contacts the switch or on the board with bare hands Pull the rear of the switch up remove the steel rule and pull the switch out of the front clip 5 To replace the switch first check that the slide contacts are properly installed in the carrier Then place the front of the switch into the front clip and push the rear of the switch down until the rear c
168. volts causing the Line Stop stage to produce a positive output at pin 8 of U75 which stops the inverter LOW VOLTAGE RECTIFIERS The Low Voltage Rectifiers stage rectifies the square wave ac voltages at the output windings of T110 to the dc levels used for all regulated supplies in this instrument AD NY LOW VOLTAGE REGULATORS AND FAN BOARD schematic diagram of the Low Voltage Regulators Fan Board circuit is given on diagram 15 in Section 8 Diagrams and Circuit Board Illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These aid in locating and identifying the components and portions of circuitry described here Sub headings in the following discussion use these stage names to further identify the components and portions of the circuitry shown on diagram 15 The Low Voitage Regulators convert semi regulated voltages from the Converter Rectifiers circuit diagram 14 to stabilized low ripple output voltages The regulators are series type using the 50 volt supply as a reference OPERATIONAL AMPLIFIER POWER SUPPLIES The operational amplifiers used to regulate the 50 15 5 50 and 15 volt supplies require that four special voltages be generated for their operation 1 The 22 volt supply is generated from the semi regulated 54 volt supply by reference zener diode VR32 and emitter follower Q34 i 2 The 22 volt supply is generated from the semi
169. when not ready 5 V at 47 source impedance when ready Output wili light a No 49 bulb GRATICULE READOUT Bnc connector on rear panel SINGLE SHOT Switching to the low level 1 V to 5 V sink less than 2 mA from the high level 10 V to 15 V sink less than 0 3 mA in less J Checks and Adjusiment 7904A TABLE 5 2 CONT Performance Check Summary ye 5 Part Part I Characteristics Performance Check equirements Procedure Title Performance Chec UNSER Procedure Tile __ REMOTE CONNECTORS AND SWITCHES CONT GRATICULE READOUT than 1 us triggers the Does not normaily require customer verification SINGLE SHOT cont Readout to display one Satisfactory operation is substantiated at the factory complete readout frame and iliuminates the graticule for approximately 0 5 s Compatibie to 15 V open collector TTL source Two probe power connectors on rear panel Probe Power Pin 3 Pin 4 Z AXIS INPUT External Polarity and Sensitivity Positive 2 V provides complete blanking from maximum intensity condition Negative 2 V provides compiete unblanking from i minimum intensity condition e Low Frequency Limit input Resistance Input Capacitance Approximately 470 0 d ener ni Less than 50 pF Open Circuit Voltage Approximately OV Max
170. 0 17 805 148 0034 00 17 812 148 0034 00 17 815 148 0034 00 A171802 108 0719 00 171805 108 0719 00 A171806 108 0718 00 171 807 108 0719 00 A171808 108 0719 00 171809 108 0718 00 171812 108 0719 00 171815 108 0719 00 AL7L816 108 0718 00 171817 108 0719 00 171818 108 0719 00 171819 108 0718 00 A17R802 321 0068 00 178805 321 0068 00 178812 321 0068 00 17 815 321 0068 00 175801 260 0723 00 175811 260 0723 00 7 44 Serial Assembly No Effective Dscont Name amp Description CIRCUIT BD 55 DELAY COMPENSATION OPTION 02 ONLY CAP FXD MICA 01 113 2 300 CAP VAR MICA DI 8 90PF 175V CAP FXD MICA 01 82 1 500 CAP FXD MICA DI 184PF 126 100V CAP FXD MICA DI 184PF 1 100V CAP FXD MICA 01 82 1 500 CAP FXD MICA DI 113PF 2 300V CAP VAR MICA D1 8 90PF 175V CAP FXD MICA DI 82PF 1 500V FXD MICA DI 184PF 1 100V FXD MICA DI 184PF 1 100V CAP FXD MICA 01 82 1 500V SEMICOND DVC DI SW 51 30V 150MA 30V D0 35 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 RELAY ARMATURE 15VDC 600 OHM RELAY ARMATURE 15VDC 600 OHM RELAY ARMATURE 15VDC 600 OHM RELAY ARMATURE 15VDC 600 OHM FIXED 805NH COIL RF FIXED 805NH COIL RF FIXED 1 75UH COIL RF FIXED 805NH COIL RF FIXED 805NH COIL RF FIXED 1 75UH COIL RF FIXED 805NH COTL RF FIXED
171. 0 315 0622 00 315 0103 00 315 0301 00 321 0350 00 315 0512 00 321 0350 00 315 0222 00 315 0621 00 315 0152 00 315 0102 00 315 0751 00 315 0751 00 315 0102 00 315 0751 00 315 0751 00 315 0102 00 315 0751 00 315 0751 00 315 0102 00 315 0751 00 315 0751 00 315 0511 00 315 0511 00 315 0511 00 321 0386 00 321 0262 00 321 0361 00 311 1224 00 311 2230 00 321 0262 00 307 0445 00 315 0102 00 315 0513 00 321 0356 00 315 0133 00 321 0344 00 315 0133 00 321 0306 00 315 0753 00 321 0373 00 321 0308 00 321 0311 00 315 0513 00 321 0356 00 321 0319 00 321 0321 00 321 0335 00 315 0154 00 315 0471 00 321 0335 00 315 0182 00 Serial Assembly No Effective Dscont 8010100 8010100 5030000 010100 030000 030000 8010100 8030000 8030000 8010100 8030000 8030000 8041952 8010100 8010100 5010100 8010100 8030000 8010100 8030000 8010100 8030000 8030000 8030000 8030000 8010100 8030000 B010100 030000 B010100 B030000 010100 030000 010100 8030000 8010100 B030000 010100 8030000 8010100 8030000 8010100 030000 8023999 8029999 8029999 8029999 8029999 041951 8029999 8029999 8029999 8029999 8029999 8029999 8029999 8029999 8029999 B029999 029999 8029999 8029999 8029999 8029999 Name amp Description RES FXD FILM 100K OHM 54 0 25W RES FXD FILM 1 5K OHM 5 0 25W RES FXD FILM 10K OHM 5 0 25W
172. 0 7 91 Replaceable Electrical Parts 7904 Tektronix Serial Assembly Mfr Component No Part No Effective _ Dscont Name amp Description Code Mfr Part No A15 672 0572 00 8010100 8029999 CIRCUIT BD ASSY READOUT PROTECTION 1 80009 672 0572 00 INCLUDES A15A1 A27 ASSEMBLIES A15 672 0572 01 8 030000 8031800 CIRCUIT BD ASSY READOUT PROTECTION 1 80009 672 0572 01 INCLUDES A15A1 A27 ASSEMBLIES A15 672 0572 02 8031801 8041951 CIRCUIT BD ASSY READOUT PROTECTION 1 80009 672 0572 02 INCLUDES A15A1 A27 ASSEMBLIES 15 672 0572 05 8041952 CIRCUIT BD ASSY READOUT PROTECTION 1 80009 672 0572 05 INCLUDES A15A1 A27 ASSEMBLIES 7 32 REV JUL 1987 Tektronix t Mo Part No ALBAL 670 1900 06 15 1 670 8620 00 15 1 670 8620 01 A15Al 670 8620 04 15 1 2101 283 0004 00 A15A1C2101 281 0774 00 A15A1C2109 283 0003 00 A15A1C2109 281 0773 00 15 1 2112 283 0077 00 15 1 2112 281 0767 00 1 162115 290 0782 00 15 1 2115 290 0804 00 15 1 2117 290 0782 00 A15A1C2117 290 0920 00 A15A1C2118 290 0804 00 A15A1C2119 290 0782 00 A15A1C2120 281 0862 00 A15A1C2121 283 0594 00 15 1 2121 281 0773 00 A15A1C2127 281 0773 00 A15A1C2135 285 0698 00 A15A1C2140 283 0103 00 A15A1C2141 281 0767 00 A15A1C2144 281 0810 00 A15A1C2145 290 0782 00 A15A1C2154 283 0630 00 A15A1C2154 283 0728 00 A15ATIC2154 283 0796 00 15 1 2155 283 0103 00 ALSAIC2155 281 0158 00 A15A1C2157 281 0773 00 A15A1C2161 281 0765 00 A1
173. 0 125W TC TO RES FXD FILM 100 OHM 54 0 25W RES FXD FILM 560 OHM 54 0 25W RES VAR 250 OHM 0 59 RES FILM 270 5 0 25 RES FXD FILM 1 5K OHM 55 0 25V RES VAR NONW 100 OHM 0 SW RES VAR 100 OHM 0 5W RES FXD FILM 1M OHM 5 0 25W RES FXD FILM 100 5 0 05 RES FXO FILM 680 OHM 5 0 25W RES FXD FILM 390 OHM 5 0 25W RES FILM 360 OHM 5 0 25W RES FILM 3K OHM 5 0 25W RES CMPSN 4 3K OHM 5 1W RES FXD FILM 40 2K OHM 125 0 125W TC TO RES FILM 68 1K 125 0 125W TC TO RES FXD FILM 51 5 0 254 RES FXD FILM 4 7K OHM 5 0 5W RES FXD FILM 4 7K OHM 5 0 SW RES FXD FTLM 49 9K OMM 15 0 5 0 RES FXD FILM 4 99K OHM 125 0 125W TC TO RES FILM 100 OHM 1 0 125W TC T0 TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL RCPT COAX CA CKT BD MT 3 PRONG BRS GLD PL SOCKET PIN TERM U W 0 03 DIA PINS Mfr Mfr Part 01121 19701 91637 19701 5 668 19701 07716 5 668 75042 32997 19701 57668 19701 19701 07716 5 668 19701 32997 57668 57668 32997 32397 19701 57668 57668 57668 19701 57668 01121 91637 19701 19701 19701 19701 75042 19701 91637 80009 80009 80009 8000
174. 0 8010100 8010100 010100 8010100 8010100 B010100 B010100 B010100 8010100 8010100 8010100 8010100 B010100 8010100 8010100 8010100 8010100 8010100 8030000 042100 8030000 8030000 8030000 8030000 8042100 8030000 8030000 8030000 8029999 8029999 8029999 8029999 8029999 8029999 8029999 8029999 8029999 B029999 8029999 029999 8029999 029999 029999 8029999 8029999 029999 8029999 8029999 8029999 8029999 B029999 8029999 8029999 8029999 8029999 8029999 029999 8042099 8042099 Replaceable Electrical Parts 7904A Code Mfr Part No Mfr Name amp Description RES FXD FILM 30 1K OHM 1 0 125W TC T0 57668 RES FILM 21 5K OHM 1 0 125W TC TO 07716 RES VAR NONWH 1K OHM 0 50 32997 RES FXD FILM 16 5K OWM 1 0 125W TC TO 19701 RES FILM 1 3K OHM 5 0 25W 57668 RES FXD FILM 13 3K OHM 125 0 125W TC TO 07716 RES FXD FILM 3 48K OHM 125 0 125W TC T0 19701 RES FXD FILM 13 7K OHM 12 0 125W TC TO 07716 RES FILM 4 42K OHM 12 0 125W 19701 RES FXD FILM 3 16K OM 15 0 1250 TC 10 07716 RES FILM 4 02K 125 0 1254 TC 10 19701 RES FILM 1 5K OHM 54 0 25W 57668 RES FILM 4 32K OHM 125 0 125W TC TO 07716 RES FILM 1K OHM 5 0 25W 57668 RES FXD FILM 20K OHM 55 0 25W 57668 RES FILM 430 5 0 25 4 19701 RES
175. 0 8031871 8010100 8031833 B010100 B030000 8031801 8041952 8010100 8030000 8031801 8041952 8010100 8021130 010100 8021637 8010100 8031871 8010100 8020000 8010100 010769 8042057 8010939 8031870 8031832 8029999 8031800 8041951 8029999 8031800 8041951 8021129 8021636 8031870 8019999 8010768 Name amp Description CIRCUIT BD ASSY FRONT PANEL CIRCUIT BD ASSY FRONT PANEL CIRCUIT BD ASSY DISPLAY CONTROLLER CIRCUIT BD ASSY TRIGGER LIGHT CIRCUIT BD ASSY TRIGGER LIGHT CIRCUIT BD ASSY MODE SWITCH CIRCUIT BD ASSY MAIN INTERFACE CIRCUIT BD ASSY MAIN INTERFACE CIRCUIT BD ASSY MAIN INTFC CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT BD ASSY FAN POWER SUPPLY LOW VOLTAGE INCLUDES A12 A22 A23 ASSEMBLIES CIRCUIT BD ASSY CONTROLLED RECTIFIER CIRCUIT BD ASSY CONTROLLED RECTIFIER PART OF 620 0283 XX CIRCUIT BD ASSY LOGIC CIRCUIT BD ASSY TRIGGER SELECT CIRCUIT BD ASSY READOUT PROTECTION 1 INCLUDES A15A1 A27 ASSEMBLIES CIRCUIT BD ASSY READOUT PROTECTION 1 INCLUDES A15A1 A27 ASSEMBLIES CIRCUIT BD ASSY READOUT PROTECTION 1 INCLUDES A15A1 A27 ASSEMBLIES CIRCUIT BD ASSY READOUT PROTECTION 1 INCLUDES A15A1 A27 ASSEMBLIES CIRCUIT BD ASSY READQUT PART OF 672 0572 XX CIRCUIT BD ASSY READOUT PART OF 572 0572 CIRCUIT BD ASSY READOUT CIRCUIT BD ASSY READOU
176. 0 A23R10 303 0184 00 23 12 308 0503 00 A23R13 304 0473 00 A23R19 302 0565 00 23821 304 0154 00 23825 315 0471 00 A23R31 303 0100 00 A23R32 315 0220 00 A23R36 315 0103 00 A23R37 301 0200 00 A23R38 315 0332 00 A23R39 301 0200 00 REV JUL 1987 Serial Assembly No Effective _ Dscont 8010100 B020000 B010100 8020000 8010100 010100 8020000 8010100 8020000 8010100 8020000 8010100 010100 8010100 8019999 8019999 8019999 019999 8019999 8019399 8019999 8019999 019999 Replaceable Electrical Parts 79044 Name amp Description CIRCUIT BD ASSY INVERTER CIRCUIT 8D ASSY INVERTER PART OF 620 0283 02 CAP FXD 01 0 02 100 07 1400V CAPACITOR RES 0 1UF 204 amp 22 OHM 10 250VAC CAP FXD CER 01 0 02UF 100 0 1400V CAP 01 0 1UF 80 20 200V DI 2200PF 10 2000V CAP FXD 01 5000 204 3000V CAP FXD 01 2200 1025 2000V CAP CER 01 5000 20 3000 CAP FXD PLASTIC 3UF 5 400V CAP FXD ELCTLT 1UF 75 10 50 CAP FXD CER DI 100PF 5 200V 01 2200 1 2000 01 0 0010 20 3000V CAP ELCTLT 75 10 50V 01 0 010 20 250 CAP FXD ELCTLT 4 70 75 10 160VDC SEMICOND DVC DI RECT SI 400V 3A SEMICOND DVC DI RECT BRDG 600V 3A FAST RCVY SEMICOND DVC DI RECT
177. 0 and column 0 during any time siot a blank space can be added to the display Decimal points can be added to the display at any time by addressing the appropriate row and column See Character Selection Matrix for location of decimal points The Decimal Point Logic and Character Position Counter stage is reset after each word by the Word Trigger pulse The Format Generator stage provides the output signals to the vertical and horizontal deflection systems of the instrument to produce the character display The binary Channel Address Code from the Channel Counter stage is connected to this stage so that the display from each channel is positioned to the area of the crt associated with the plug in and channel originating the word see Fig 3 8 The positioning current or decimal point location current generated by the Decimal Point Logic and Character Position Counter stage is added to the Horizonta X signal at the input to the Format Generator stage to provide horizontal positioning of the characters within each word The X and Y Readout signals are connected to the Horizontal Amplifier and Vertical Amplifier through the X and Y Buffer stages The Word Trigger stage produces a trigger from the End of Word pulse generated by the Time Slot Counter stage after the tenth time slot This Word Trigger pulse advances the Channel Counter to display the information from the next channel or plug in It also provides a reset pulse to the Zeros L
178. 00 A28R942 315 0201 00 A28R943 315 0100 00 A28R950 315 0270 00 A28R951 303 0272 00 A28R952 301 0333 00 A28R960 303 0222 00 A28RT233 307 0122 00 28 150 214 0579 00 28 151 214 0579 00 28 152 214 0579 00 A28TP153 214 0579 00 28 160 214 0579 00 2 161 214 0579 00 28 550 214 0579 00 28 610 214 0579 00 28 750 214 0579 00 A28VR930 152 0149 00 A2BVR950 152 0282 00 REV JUL 1987 Serial Assembly No Effective Dscont B010100 8010769 8010100 8010769 8010768 8010768 Replaceable Electrical Parts 79044 Name amp Description RES FILM 1K OHM 5 0 25W RES FXD FILM 30 OHM 5 0 25W RES FILM 4 3K 5 0 25W RES FXD FILM 22 OHM 54 0 25 RES FXD FILM 30 OHM 5 0 25W RES FILM IK OHM 55 0 25W RES FXD FILM 22 5 0 25 RES FXD CMPSN 4 7 OHM 55 0 25W RES FXD FILM 800 OHM 0 5 0 5W TC T0 RES VAR NONWW 1K 0 50 RES FXD FILM 800 0 525 0 54 TC TO RES FXD Wf 1 5K OHM 1 3M RES FXD Wf 1 5K OHM 1 3M RES FXD FILM 47 5 OHM 0 5 0 125W TC TO RES FXD FILM 1K OHM 5 0 25W RES FXD FILM 1 33K OHM 1 0 125W TC T0 RES FXO FILM 5 49K OHM 1 0 125W TC TO RES FILM 5 23K 0HM 1 0 1254 TC TO RES FILM 910 OHM 575 0 25W RES FXD FILM 8 2K OHM 52 0 25M RES FXD FILM 750 OHM 5 0 25W RES FILM 3 3K 5 0 25 RES FXD F
179. 00 A5R362 315 0202 00 RES FXD FILM 2K OHM 5 0 25W 57668 NTR25J E 2K A5R363 315 0162 00 RES FILM 1 6K OHM 5 0 25W 19701 5043CX1K6003 A5R365 307 0108 00 RES CMPSN 8 2 OHM 5 0 25W 80009 307 0109 00 A5R366 315 0202 00 RES FXD FILM 2K OHM 5 0 25W 57668 NTR2SJ E 2K ABR367 307 0109 00 RES FXD CMPSN 8 2 OHM 5X 0 25M 80009 307 0109 00 5 368 315 0512 00 RES FXD FILM 5 1K OHM 52 0 25W 57668 NTR25J EOBK A5R372 315 0823 00 RES FILM 82K OHM 55 0 25W 57668 NTR25J E82K A5R373 321 0258 00 RES FXD FILM 4 75K OHM 125 0 1250 TC TO 119701 5033ED4K750F A5R374 321 0822 06 RES FXD FILM 1 76K OH4 0 25 0 125W TC T9 19701 5033RELK760C A5R375 311 1566 00 RES VAR NONWW 200 0 5 4 32997 3352T i 201 A5R376 321 0321 07 RES FXD FILM 21 5K OHM 0 1 0 125W TC T9 19701 5033 21 50 ASR380 315 0362 00 RES FXD FILM 3 6K OHM 5 0 25W 19701 5043 3 600 7 12 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr nt No Part No Effective Dscont Name amp Description Code Mfr Part No 5838 321 0321 07 RES FILM 21 5K 0 1 0 1259 TC T9 19701 5033RE21K50B ASR382 315 0123 00 RES FILM 12K OHM 5 0 25W 57668 NTR25J E12K0 A5R383 321 0164 00 RES FILM 499 OHM 1 0 125W TC TO 19701 5033ED499ROF 58384 308 0307 00 RES WW 5 126 3W 00213 12405 5000 1 A5R385 311
180. 00 8010100 B029999 RES FXD FILM 3 92K OHM 14 0 125W TC TO 07716 CEAD39200F A15A1R2277 321 0218 00 8030000 RES FILM 1 82K OMM 14 0 1259 TC TO 19701 5033EDIK82F AL5A1R2278 315 0823 00 8010100 B029999 RES FILM 82K OHM 5X 0 25wW 57668 NTR25J E82K A15A1R2279 321 0222 00 8010100 8029999 RES FXD FILM 2 00K OHM 125 0 125W TC TO 19701 5033ED2KOO0F 15 182279 321 0221 00 8030000 RES FILM 1 96K OHM 12 0 125W TC TO 19701 5043 01 950 15 182280 315 0823 00 8010100 8029999 RES FILM 82K 5 0 25 57668 NTR25J E82K 15 182280 321 0254 00 8030000 RES FILM 4 32K 12 0 125W TC TO 07716 CEAD43200F 15 182281 315 0101 00 8010100 8029999 RES FILM 100 OHM 5 0 258 57668 251 100E 15 182282 315 0332 00 8010100 029999 RES FXD FILM 3 3K 5 0 254 57668 NTR25J EO3K3 15 182283 315 0753 00 8010100 8029999 RES FILM 75K 5 0 25 57668 NTR25J E75KQ A15A1R2284 321 0216 00 8010100 B029998 RES FILM 1 74K OHM 195 0 125W TC TO 07716 CEAD17400F 15 182285 321 0245 00 8010100 8029999 RES FXO FILM 3 48K 1 0 125W TC TO 19701 5033 03 8 15 182285 321 0242 00 021190 8029999 RES FILM 3 24K OMM 125 0 125W TC TO 19701 5043ED3K240F 15 182285 321 0243 00 8021190 5029999 RES FILM 3 32K OHM 1 0 125W TC T0 19701 5033ED3K32F 15 182285 321 0244 00 8021190 029999 RES FIL
181. 00 8029999 MICROCKT DGTL DECIMAL POINT amp SPACE 80009 155 0019 00 A15A1U2263 156 0140 02 8030000 MICROCKT DGTL HEX BUFFERS W OC HV QUT 18324 N7417 NB OR FB A15A1U2264 156 0480 02 8030000 MICROCKT DGTL QUAD 2 INP amp GATE SCRN 01295 SN74LSOBNP3 A15A1U2270 155 0023 00 8010100 8029999 MICROCKT DGTL CHARACTER GENERATOR NUM 80009 155 0023 00 A15A1U2272 155 0024 00 8010100 8023999 MICROCKT DGTL CHAR GEN SPCL SYMBOLS 80009 155 0024 00 A15A1U2274 155 0025 00 8010100 8029999 MICROCKT DGTL CHAR GEN PREFIXES 80009 155 0025 00 A15A1U2276 155 0026 00 010100 B029999 MICROCKT DGTL CHARACTER GENERATOR LETTERS 80009 155 0026 00 A15A1U2276 156 1191 00 8030000 MICROCKT LINEAR DUAL BI FET OPNL AMPL 01295 TLO72CP A15A1U2278 155 0027 00 010100 B029999 MICROCKT DGTL CHAR GEN SPECIAL ALPHA 80009 155 0027 00 2284 155 0020 00 010100 029999 MICROCKT DGTL CHANNEL SW OUTPUT ASSY 80009 155 0020 00 A15A1VR2185 152 0405 00 8 030000 SEMICOND DVC DI ZEN SI 15V 5X 1W TO 41 12954 7841205 AL5ALVR2186 152 0405 00 6030000 SEMICOND DVC DI ZEN SI 15V 5 1W 10 41 12954 07841205 ALSALVR2187 152 0405 00 030000 SEMICOND DVC DI ZEN SI 15V 5 1W 10 41 12954 DZ841205A ALSALVR2262 152 0405 00 010100 029999 SEMICOND DVC DI ZEN SI 15V 54 1W 70 41 12954 07841205 15 1 62263 152 0405 00 010100 029999 SEMICOND DVC DI ZEN SI 15V 54 1W TO 41 12954 04841205 1 1 2 152 0405 00 010100 8029999 SEMICOND DVC DI ZEN S1 15V 5 1W 10 41 12954 02841205
182. 0177 00 A13C4302 283 0177 00 13 4303 283 0177 00 A13C4304 283 0177 00 A13C4305 290 0755 00 A13C4314 283 0672 00 13 4315 281 0603 00 13 4316 283 0177 00 A13C4335 281 0603 00 13 4336 281 0549 00 13 4342 283 0032 00 13 4343 281 0782 00 13 4345 281 0782 00 A13C4346 283 0032 00 13 4347 283 0638 00 A13C4423 281 0603 00 13 4441 281 0603 00 13 4449 283 0003 00 13 4461 281 0589 00 13 4467 281 0589 00 13 4470 283 0111 00 13 4475 283 0177 00 A13C4483 283 0000 00 13 4484 283 0177 00 13 4485 283 0060 00 13 84322 152 0242 00 AL3CR4323 152 0322 00 13 84354 152 0141 02 AL3CR4355 152 0141 02 13 84356 152 0141 02 A13CR4357 152 0141 02 A13CR4368 152 0141 02 13 84369 152 0141 02 A13CR4433 152 0141 02 AL3CR4434 152 0141 02 13 84448 152 0141 02 13 84449 152 0141 02 1 4461 152 0141 02 AL3CR4467 152 0141 02 AL3CR4471 152 0153 00 A13CR4472 152 0141 02 A13CRA473 152 0141 02 A13CR447A 152 0141 02 A13CR4487 152 0075 00 A13CRA487 152 0664 00 13 84491 152 0075 00 AL3CR4492 152 0141 02 13 84493 152 0141 02 A13CR4494 152 0581 00 13 84495 152 0141 02 A13CRA496 152 0141 02 A13CR4498 152 0141 02 A13CR4499 152 0581 00 41344406 131 1003 00 A13L4301 108 0245 00 1314302 108 0245 00 1314303 108 0245 00 REV JUL 1987 Serial ssembly No Effective Dscont 8010100 8021705 8021704 Replaceable Electrical Parts 7904 Name amp Description CIRCUIT BD ASS
183. 0190 00 181930 315 0431 00 AiR1931 315 0510 00 1 1932 323 0189 00 181933 315 0101 00 181934 315 0301 00 181935 315 0473 00 181936 315 0101 00 AIR1937 315 0123 00 181938 315 0331 00 181940 315 0510 00 1 1941 315 0510 00 181942 315 0204 00 181943 321 0097 00 4181944 32i 0262 00 181945 301 0102 00 AiR1948 321 0097 00 1 1948 321 0190 00 1 1950 315 0223 00 1 1951 321 0481 00 4181952 321 0289 00 181953 315 0104 00 181954 315 0104 00 181955 315 0103 00 181956 315 0243 00 AiR1957 315 0821 00 AiR1960 321 0260 00 A RI983 321 0283 00 AiR1964 321 0205 00 181965 321 0260 00 1 1966 315 0103 00 REV JUL 1987 Serial Assembly No Effective Dscont B010100 8042058 042057 Replaceable Electrical Parts 7904A Name amp Description RES FXD CMPSN 300 OHM 5 1W RES VAR NONWW PNL 10K OHM 1W W SW RES FILM 10M OHM 55 0 25W RES VAR NONWH LOK OHM 0 SW RES FXD FILM 100 OHM 5 0 25W RES FXO FILM 10K OHM 5 0 25W RES FXO FILM 10K OHM 52 0 25W RES FXD FILM 5 1K OHM 5 0 25W RES FXD FILM 240 OHM 5 0 25W RES FILM 100K 525 0 25W RES FXD FILM 301 1 0 1258 TC TO RES FXD FILM 470 OHM 5 0 25W RES FXD FILM 200 OHM 5 6 0 25M RES FILM 100K OHM 5 0 25W RES FILM 5 1K OHM 55 0 25M RES FXD FILM 15K OHM 575 0 25W RES FXD FILM 10M OHM 57 0 25W RES FXD
184. 05 188210 317 0150 00 RES FXD CMPSN 15 5 0 125 01121 881505 A18R211 311 1757 00 RES VAR NONWH 2 5K ORM 10 5W LIN CERMET 73138 82PR2 5K 124C A18R212 321 0172 00 RES FXD FILM 604 OHM 1 0 125W TC TO 19701 5033ED604ROF 188 213 321 0179 00 RES FXD FILM 715 OHM 1 0 125W TC TO 07716 CEAD715ROF 188214 315 0181 00 RES 180 5 0 25 57668 NTR25J E180E 188215 311 0978 00 RES VAR NONWW TRMR 250 OHM 0 SW 73138 82PR250 37C 188220 321 0171 00 RES FILM 590 OHM 1 0 125W TC TO 19701 5033ED590ROF Al8R221 317 0047 00 RES FXD CMPSN 4 7 5 0 125 01121 84765 Al8R222 317 0100 00 RES FXD CMPSN 10 GHM 5 0 125W 01121 881005 A18R223 317 0150 00 RES FXD CMPSN 15 OHM 5 0 125W 01121 881505 A18R230 321 0365 00 RES FXD FILM 61 9K OHM 125 0 1254 TC TO 07716 CEAD61901F A18R231 321 0361 00 RES FILM 56 2K OHM 195 0 1254 TC T0 07716 CEADS6201F A18R232 321 0402 00 RES FILM 150K OHM 125 0 1254 TC TO 19701 5033ED150K0F 188233 321 0435 00 RES FXD FILM 332K OHM 1 0 125W 07716 CEAD33202F 186234 321 0357 00 RES FXD FILM 51 1K OHM 12 0 1250 0 07716 CEADSIi0iF A18R235 321 0357 00 RES FXD FILM 51 1K OHM 125 0 125W TC TO 07716 CEADS1101F A18R236 321 0357 00 RES FXD FILM 51 1K OHM 12 0 125W TC TO 07716 51101 188237 311 1214 00 RES VAR NONWW 200K OHM O0 5W 32997 3386 04 204 Ai8R238 311 1214
185. 075 100V CAP DI 0 01UF 10 100V CAP DI 1500PF 5 200V CAP FXD CER DI 0 01UF 107 1000 CAP FXD CER DI 0 01UF 107 100V CAP FXD CER DI 0 01UF 10 100V CAP FXD CER 01 27 20 100 FXD MICA 01 890 2 100 FXD MICA 01 160 1 1007 DI 470PF 54 500V CAP CER 01 470 10 100 DI 470PF 107 100V CAP 01 0 0010 100 0 500 01 0 010 10 100V 01 0 020 80 20 150 CAP FXD CER 01 0 022 0 20 100 CAP 01 0 010 1075 1000 Mfr Code Mfr Part No 80009 80008 80009 80009 59660 04222 59821 04222 59660 04222 55680 55680 55680 55680 55680 55680 04222 00853 04222 04222 19396 59821 04222 04222 55680 00853 00853 00853 59821 59660 04222 04222 04222 59660 04222 59660 04222 04222 04222 04222 59660 04222 04222 04222 04222 00853 00853 59660 04222 04222 59680 04222 59660 04222 04222 670 1900 06 670 8620 00 670 8620 01 670 8620 04 855 55825 02032 201 223 D10324025UJDCEX MA201C103KAA 831 5008331J 106 331 ULBIVAR7TAAANA ULBLELOOTAAANA ULBIVAR7TAAANA ULB1V33OTAAANA ULBLELOOTAAANA ULBiV4R7TAAANA MALOLCLOZMAA 0151 102 0 201 103 MA201C103KAA DU490 74 28217 2DDH 3L181J 106 331 101 5 6
186. 1 80009 32997 57568 01121 01121 01121 01121 01121 01121 01121 01121 01121 75042 01121 01121 01121 01121 01121 32997 07716 01121 19701 01121 57668 57668 01121 19701 32997 07716 Mfr Part No JH005 3011JA JH005 3011JA 48283 036 48283 029 48283 029 48283 036 48283 036 552821 15505 20 0 5 2725 81005 84725 84725 1555 1555 1045 1835 82265 82025 81045 315 0105 03 307 1135 00 72MANO485505M EB3055 EB2255 315 0103 03 33295 158 203 NTR25J E12K0 CB1835 CB2265 81015 1045 4725 84725 CB4725 CB3315 CB1015 BW 20 1R500K CB1045 CB1005 EB1015 1365 A BRADLEY CB2035 33295 58 253 029402 1025 5043CX470K092U 83315 NTR25J E680E NTR25J EOGK3 EB6235 S043CX15R00J 33295 58 104 64900 7 51 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr Component Part No Effective _ Dscont Name amp Description i Code Mfr Part 208155 311 1282 00 RES VAR NONW 5K OHM O 5W 32997 33295 158 502 208156 321 0310 00 RES F1LM 16 5K 0HM 125 0 125V TC T0 19701 5033 016 50 A20114 120 1281 00 XFMR PWR SDN amp SU HIGH VOLTAGE B0009 120 1281 00 A20TP78 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 20 79 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 20 113 214 0579 00 TERM TEST POINT 8RS CD PL 80009 214 0579 00
187. 1 8K OHM 5 0 25 RES FILM 20K 5 0 259 RES FXD FILM 20K OHM 5 0 25M RES FILM 4 7K 5 5 0 25W RES FXD FILM 330K OHM 5 5 0 25W RES FILM 750K 5 5 0 25W MI TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL MICROCKT DGTL POWER SPLY RGLTR MICROCKT OGTL TRIPLE 3 INP amp GATE SCRN SEMICOND 01 7 51 18 5 0 44 00 7 SEMICOND DVC DI ZEN S1 15V 5 0 4W D0 7 SEMICOND DVC DI ZEN SI 9V 5 0 5W DO 7 Mfr Code Mfr Part No 57668 57668 57668 19701 57668 07716 19701 19701 91637 19701 19701 57868 57668 19701 32997 TK1450 57668 07716 19701 57668 01121 57668 57668 19701 57668 19701 57668 57668 57668 57668 57658 57658 19701 80009 80009 80009 01295 04713 04713 04713 NTR25J E150K NTR25J E56E0 NTR25J E56E0 5043ED39K20F NTR25J E470E CEAD29401F 5043 034 00 S033ED1 KOOF CMF55116G11R00F 5043ED8K87 0F 5043ED8K660F NTR25J E01K2 NTR25J EO2K7 5043CX1M000J 3386 07 252 GFOGVT 2 OHM NTR25J E 20K CEAD22602F 5043CX15R00J NTR25J E 100 3915 NTR25J E47K0 NTR25J EO4K7 5043CX1 0RROOJ NTR25J E270K 5043CX470K082U NTR25J EO2K7 NTR25J E1KB NTR25J E 20K NTR25J E 20K NTR2SJ EOAK7 NTR25J E 330K 5043 750 214 0579 00 214 0579 00 155 0067 02 SN74LSLINP3 52635014 2 713203 119658 SZ50646RL REV JUL 1987 Tektronix t No Part No 13 670 4777 20 13 4301 283
188. 1 through TS 10 time slots 1 through 10 and are connected to the vertical and horizontal plug in compartments as weil as to various stages within the Readout System The output lines are energized se quentially so there is a pulse on only one of the 10 lines during any 250 microsecond timing period After the Time Slot Counter stage has counted time slot 10 it produces an End of Word pulse which advances the system to the next channel REV NOV 1985 Theory of Operation 7904A Two output lines row and column are connected from each channel of the plug in unit back to the Readout System Data is typically encoded on these output lines by connect ing resistors between them and the time slot input lines The resultant output is a sequence of 10 analog current levels that range from 0 to 1 millampere 100 microamperes step on the row and column output lines This row and column corresponds to the row and column of the Character Selec tion Matrix in Figure 3 20 The standard format for encoding information onto the output lines is given in Table 3 11 Spe Cial purpose plug in units may have their own format for readout and these special formats will be defined in the manuals for these units The encoded column and row data from the plug in units is selected by the Column Data Switch and Row Data Switch stages respectively These stages take the analog current from the 8 data lines 2 channels from each of the 4 plug in compartments
189. 12 6012 0 2527 1N4152 DA2527 1N4152 FDH 6012 FDH 6012 FDH 6012 FDH 6012 FDH 6012 FDH 6012 6012 FDH 6012 REV JUL 1987 t No 12 1 890 12 1 120 12 1 121 12 1 8122 12 1 8123 12 1 124 12 1 125 12 1 8127 12 1 8130 12 1 8131 12 1 8132 12 1 8133 AL2A1CR140 12 1 8141 Ai2AlCR14 12 1 143 12 1 lt 151 12 1 161 12 1 161 12 1 171 12 1 8183 12 11132 Ai2A1L134 A12A1L142 Al2Al1L144 12 152 12 411154 12 1 5 12 1 40 12 1 48 12 1 50 Al2A1P52 12 1 54 12 1052 A12A1054 A12A10162 A12A10162 12 10171 12 10171 12 10173 A12A10173 A12A10177 A12A1Q177 Al2AIRS2 12 1854 12 1855 12 1 59 AL2A1R60 12 1861 AL2A1R62 12 1863 12 1864 12 1886 REV JUL 1987 Tektronix Part No 152 0141 02 152 0242 00 152 0242 00 152 0242 00 152 0242 00 152 0242 00 152 0242 00 152 0242 00 152 0586 00 152 0586 00 152 0586 00 152 0586 00 152 0397 00 152 0397 00 152 0397 00 152 0397 00 152 0692 00 152 0008 00 152 0725 00 152 0141 02 152 0141 02 108 0473 00 108 0473 00 108 0680 00 108 0580 00 108 0473 00 108 0556 00 131 0608 00 131 0589 00 131 0608 00 131 0608 00 131 0608 00 131 0608 00 151 0302 00 151 0273 00 151 0190 05 151 0190 00 151 0190 05 151 0190 00 151 0188 03 151 0188 00 151 0188 03 151 0188 00
190. 1225 00 RES VAR NONW 1K 0 5 32997 3386 04 102 A5R387 321 1611 07 RES 550 OHM 0 1 0 125W TC T9 19701 5033RE550R0B ASR389 321 1008 04 RES FXD F1LM 12 0 OHM 0 1 0 125W TC T2 57668 CRBi4 BYE 12 OHM A5R392 321 1612 07 RES FXD FILM 4 455K OHM 0 1 0 125W TC T9 19701 5033RE4K455B A5R393 321 1611 07 RES FILM 550 OHM 0 1 0 125W TC T9 19701 5033 550 ABR394 321 1612 07 RES FXD FILM 4 455K OHM 0 1 0 125W TC T9 19701 5033RE4K4558 ASR395 321 1611 07 RES FILM 550 OHM 0 1 0 125W TC T9 19701 50338 550808 A5R396 321 1612 07 RES FXD FILM 4 455K OHM 0 1 0 125W TC T9 19701 5033 4 55 A5R397 321 0813 07 RES FILM 495 OHM 0 1 0 125W TC T9 19701 50338 4950 55315 263 0021 02 SWITCH PB ASSY 4 LATCH 7 5 8 CONTACTS 80009 263 0021 02 55325 263 0022 02 SWITCH PB ASSY 5 LATCH 7 5 MM 10 CONTACTS 80009 263 0022 02 55345 263 0013 10 SWITCH PB ASSY 3 LATCH 10 MM W 3 CONTACTS 80000 263 0013 10 A5S365 263 0013 10 SWITCH PB ASSY 3 LATCH 10 MM W 3 CONTACTS 80009 263 0013 10 55395 263 0013 11 SWITCH PB ASSY 3 1 10 MM 5 CONTACTS 80009 263 0013 11 5 301 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A5TP362 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 5 363 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 5 365 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 36 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0
191. 15 0472 00 8030000 RES FILM 4 7K OHM 5 0 25W 57668 NTR25J E04K7 A15A1R2250 315 0222 00 8030000 8041951 RES FILM 2 2K OHM 5 0 25W 57668 NTR25J EO K2 15 1 2250 315 0621 00 8041952 RES FILM 620 OHM 525 0 254 57668 NTR25J EG20E AL5SAIR2251 315 0102 00 010100 8029999 RES FILM 1K OHM 52 0 25W 57668 NTR25JEO1KO 15 1 2251 315 0203 00 8030000 041951 RES FILM 20K 5 0 25 57668 NTR25J E 20K 15 182251 315 0472 00 8041952 RES FXD FILM 4 7K OHM 52 0 25W 57668 NTR253 E04K7 15 182252 315 0102 00 010100 8029999 RES FILM 1K 5 0 25 57668 25 01 0 REV JUL 1987 Replaceable Electrical Parts 7904 7 97 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr nt No Part No Effective _ Dscont Name amp Description Code Mfr Part 1 1 2252 321 0202 00 8030000 RES FILM 1 24K 1 0 125 70 24546 5501241 15 182253 315 0102 00 010100 8029999 RES FILM 1K OHM 5 0 25M 5 668 X NTR25JEO1KO A15A1R2253 321 0202 00 8030000 RES FILM 1 24K OHM 12 0 1254 TC TO 24546 5501241 15 1 2254 315 0303 00 010100 8029999 RES FILM 30K 5 0 25 19701 5043 30 000 15 182254 321 0254 00 8030000 RES FILM 4 32 OHM 15 0 125W TC TO 07716 043200 15 1 2255 321 0302 00 8030000 RES FILM 13 7K OM 126 0 125W
192. 152 0141 02 SEMICOND DVC DI 5W SI 30V 150MA 30V D0 35 03508 2527 184152 21 886 152 0066 03 SEMICOND DVC DI RECT S1 400V 1A DO 41 14433 L64017 21 8127 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 184152 A21CR143 152 0071 00 8010100 8021636 SEMICOND DVC D1 SW GE 15V 40MA 00 7 15238 0865 A21CR143 152 0725 00 B021637 SEMICOND DVC DI SI SCHOTTKY 20V 1 2PF D0 35 21847 2 1582 A21CR152 152 0141 02 SEMICOND 0VC DI SW S1 30V 150MA 30V D0 35 03508 DA2527 184152 A21CR153 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 DA2527 184152 A21CR173 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 042527 1 4152 A21CR177 152 0233 00 SEMICOND DVC DI SW S1 80V 75MA DO 7 03508 DA2737 A21CR184 152 0141 02 SEMICOND DVC DI SW SI 30V L50MA 30V 00 35 03508 DA2527 1N4152 A21J37 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 42178 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A213110 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A21P20 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22525 48283 036 QUANTITY OF 10 REV JUL 1987 7 53 Replaceable Electrical Parts 7904A Tektronix Serial Assembly Mfr t No Part No Effective Dscont Name amp Description Code Mfr Part No A21P57 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 7 A21P65 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLO PL 22506 4828
193. 177 00 CAP 01 80 20 25V 04222 SR302ETODZAATR A140449 290 0527 00 ELCTLT LSUF 20 20V 05397 3688156 020 5 14 447 283 0221 00 D1 0 47UF 20 50V 04222 3430 050 474M 14 450 290 0488 00 CAP ELCTLT 2 2UF 10 20V 05397 13228225 020 5 14 483 283 0260 00 DI 5 6PF 0 25PF 200V 51642 150 200NPO569C 14 483 283 0168 00 CAP DI 12PF 5X 100V 05397 C315C120316G5CA 14 483 283 0159 00 CAP FXD CER DI 18PF 54 50V 04222 5 155 180 A14C483 283 0201 00 CAP FXD CER DI 27PF 10 200V 05397 C312C270K2G5CA C483 IS SELECTABLE 14 486 281 0775 00 01 0 20 50 04222 205 104 14 487 283 0111 00 01 0 0 20 50 05397 330 104 5 1 A14C488 281 0775 00 CAP CER D1 0 20 50 04222 MA205E104MAA A14C490 283 0339 00 CAP FXD CER D1 0 22UF 102 50V 05397 C330C224K5R5CA A14C493 283 0260 00 01 5 6PF 0 25PF 200V 51642 150 200NPO569C A14C493 283 0168 00 CAP FXD CER DI 12PF 5X 100V 05397 315 1200165 A14C493 283 0159 00 CAP FXD CER DI 18PF 5X 50V 04222 58155 180 A14C493 283 0201 00 CAP DI 27PF 10 200V 05397 C312C270K2G5CA C493 IS SELECTABLE A14J202 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A14J203 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00
194. 200MA 00 35 SW S1 55V 200MA 00 35 SW SI 55V 200MA 00 35 SW S1 55V 200MA 00 35 SW SI 55V 200MA 00 35 SW SI 55V 200MA D0 35 SW ST 55V 200MA D0 35 SW SI 55V 200MA 00 35 SW ST 55V 200MA 00 35 SW ST 55V 200 D0 35 SW SI 55 200 00 35 SW SI 55 200 00 35 SW SI 55V 200MA 00 35 SM SI 55V 200MA D0 35 SW S1 55V 200MA 00 35 SW ST 55V 200MA DO 35 SW S1 55V 200MA 00 35 SW ST 55V 200MA 00 35 54 51 55 200 00 35 54 51 55 200 00 35 SW ST 55 200 00 35 SW SI 55V 200M 00 35 SW 1 55V 200MA 00 35 SW S1 55V 200MA 00 35 SW S1 55V 200MA D0 35 SW S1 55V 200MA 00 35 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 10 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 10 Mfr Code Mfr Part No 80009 670 4346 00 07263 6012 07263 FDH 6012 07263 6012 07263 FDH 5012 07263 FDH 6012 07263 6012 07263 FDH 6012 07263 FDH 6012 07263 6012 07263 FDH 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 FDH 6012 07263 6012 07263 FDH 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263 6012 07263
195. 25 TC TO RES FILM 1K OHM 14 0 125W TC TO RES FXD FILM 40 2K OHM 125 0 125W TC TO RES FILM 20 0K OHM 125 0 125 TC T0 RES FILM 3K OHM 54 0 25W RES FXD FILM 1K OHM 55 0 250 RES FXO FILM 15K OHM 525 0 25M RES FILM 49 9 OHM 0 54 0 125W TC TO RES FXD FILM 7 5K 5 0 25 RES FXD FILM 1 2K OHM 5 0 25W RES FXD FILM 12 1K OHM 126 0 125W TC TO RES FXD FILM 21 0K OHM 1 0 125W TC T0 RES FXD FILM 69 8 OHM 125 0 5W TC TO RES FILM 69 8 OHM 1 0 5W TC T0 RES FXO FILM 169 OHM 1 0 5W TC TO RES FXD FILM 10 0K OHM 1 0 125W TC TO RES FXD FILM 23 2K OHM 1 0 125W TC TO RES FILM 4 7K OHM 545 0 25W RES FILM 3 6K OHM 55 0 25W RES FXD FILM 3 6K OHM 5 0 25V RES VAR 50K 0 SW RES VAR 50K OHM 0 SW RES FXD FILM 20K OHM 515 0 25W RES FXD FILM 200K OHM 5 0 25W RES FXD FILM 100K OHM 55 0 25W RES FXD FILM 220K OHM 55 0 25W RES FILM 1K OHM 54 0 25W RES THERMAL 50 OHM 5 0 125W Mfr Code Part 01121 07716 24546 19701 19701 19701 19701 07716 19701 19701 24546 24546 57668 19701 07716 75042 19701 19701 07716 07716 19701 57668 57668 91637 91637 19701 19701 19701 19701 07716 19701 19701 91637 19701 57668 57668 19701 91637 57668 57668 07716 19701
196. 265 00 315 0512 00 315 0103 00 321 0730 06 311 1225 00 321 0331 09 315 0151 00 315 0104 00 315 0821 00 315 0331 00 315 0471 00 315 0181 00 315 0512 00 308 0365 00 315 0432 00 304 0102 00 315 0121 00 315 0123 00 301 0182 00 315 0203 00 315 0103 00 321 0924 07 321 0924 07 315 0151 00 315 0104 00 315 0821 00 315 0511 00 315 0471 00 315 0181 00 315 0512 00 308 0686 00 321 0332 07 321 1296 07 315 0152 00 315 0123 00 315 0302 00 315 0822 00 315 0201 00 315 0393 00 308 0804 00 315 0151 00 315 0432 00 321 0924 07 321 1296 07 315 0912 00 315 0102 00 315 0123 00 315 0302 00 315 0201 00 Serial Assembly No Effective _ Dscont Replaceable Electrical Parts 7904 amp Description TRANSISTOR NPN SI TO 18 TRANSISTOR SELECTED 2N3904 TRANSISTOR PNP 51 TD 127 RES FILM 68 1K OHM 125 0 125W TC TO RES FXO FILM 102K OHM 125 0 1259 TC TO RES FXD 30 9K OM 175 0 125W TC TO RES FXO FILM 10 2K OHM 12 0 125W TC TO RES FXD FILM 20 5K OHM 175 0 125W TC TO RES FILM 3 3K OHM 5 0 25W RES FXD FILM 5 62K OHM 175 0 SW TC 10 RES FILM 5 1K OHM 5 6 0 258 RES FILM 10K 0HM 54 0 25W RES FXD FILM 5 703K OHM 0 275 0 125W TC T9 RES VAR NONWW TRMR IK OHM 0 W RES FXD FILM 27 4K OHM 1 0 125W TC T9 RES FXD FILM 150 OHM 57 0 25W RES FXD FILM LOOK OHM 5 0 25W RES FXD FILM 820 O
197. 27 1N4152 ALSAICR2198 152 0141 02 8010100 8029999 SEMICOND DVC DI SW 51 30 150 30V D0 35 03508 DA2527 1N4152 1 1 2226 152 0141 02 8010100 029999 SEMICOND DVC DI SW ST 30V 150MA 30V D0 35 03508 DA2527 1N4152 AL5AICR2229 152 0141 02 8030000 SEMICOND DVC DI SW SI 30V 150MA 30 00 35 03508 2527 1N4152 AL5A1CR2267 152 0141 02 8930000 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 03508 2527 184152 A15A1CR2270 152 0141 02 8030000 SEMICOND DVC D1 SW ST 30V 150MA 30V 00 35 03508 DA2527 1N4152 ALSAICR2271 152 0141 02 8030000 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 03508 0 2527 1N4152 15 1 2132 276 0532 00 031801 SHLD BEAD ELEK FERRITE 02114 55 590 65 4 A15A1J2132 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A15A132138 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A15A132139 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 15 1 2192 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A15A1J2296 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A15A1J2299 131 1003 00 CONN RCPT FLEC CKT BD MT 3 PRONG 80009 131 1003 00 A15A1L2212 108 0800 00 030000 COIL RF FIXED 820MH 04072 9230 90 A15A1L2277 108 0800 00 B030000 COIL RF FIXED 820MH 04072 9230 90 15 112283 108 0331 00 010100 8029999 COIL RF FIXED 758NH TK1345 108 0331 00 15 1 2165 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QU
198. 28 6 Check Vertical Display 5 29 A Z AXIS AND DISPLAY 7 Check Vertical Trace Separation B 1 Z Axis and Display Preliminary Setup 5 15 Operation D 5 30 2 Check 5 15 F READOUT SYSTEM B CALIBRATOR AND OUTPUT SIGNALS 1 Readout System Preliminary Setup 5 31 1 Calibrator and Output Signals 2 Check Readout Modes 5 31 Preliminary Setup 5 16 2 Check Calibrator Output Voltage 5 16 3 Check Calibrator 1 kHz Repetition oben br ACCU 5 17 2 ee PERFORMANCE CHECK 5 Check and B Sawtooth Output POWER UP SEQUENCE ccce URN ae ees ees 5 19 6 Check A and B Gate Output Signals 5 19 The performance of this instrument can be checked at 7 Check Graticule Hiumination Operation 5 20 any ambient temperature from 0 to 50 C unless otherwise stated C TRIGGER SYSTEM 1 Trigger System Preliminary Setup 5 21 1 Check that the 7904A has been set for the proper 2 Check Vertical Signal Out DC power source and also that a suitable power cord Centering 5 21 and plug has been attached Refer to Power Source 3 Check Trigger Selector Operation 5 22 Information in Section 1 General Information for specific details D HORIZONTAL SYSTEM 1 Horizontal System Preliminary Setup 5 25 2 Conne
199. 290 0768 00 A12A1C133 290 0768 00 A12A1C134 290 0768 00 12 1 135 290 0768 00 AL2AIC142 290 0772 00 A12A1C143 290 0770 00 12 1 144 290 0772 00 12 1 145 290 0770 00 12 1 152 290 0771 00 12 1 153 290 0771 00 12 1 155 290 0773 00 12 1 156 290 0771 00 12 1 172 290 0746 00 A12A1C179 283 0177 00 010100 12 1 179 285 1338 00 8031833 12 1 183 283 0111 00 010100 12 1 183 285 1300 01 031833 12 1 852 152 0333 00 12 1 59 152 0333 00 ALZAICR65 152 0141 02 12 1 866 152 0141 02 12 1 73 152 0333 00 12 1 74 152 0333 00 12 1 75 152 0333 00 12 1 876 152 0333 00 Ai2AiCRBl 152 0333 00 2 1 2 152 0333 00 12 1 83 152 0333 00 12 1 84 152 0333 00 7 22 Serial Assembly No Effective _ Dscont B031832 B031832 B031832 8031832 8031832 8031832 B031832 B031832 8031832 8031832 8031832 Name amp Description CIRCUIT BD ASSY CONTROLLED RECTIFIER CIRCUIT BD ASSY CONTROLLED RECTIFIER PART OF 620 0283 XX CAP FXD CER DI 0 01UF 480 207 150V CAP FXD MTLZD 0 O1UF 10 63V CAP FXD ELCTLT 2 7UF 20 50V CAP DI 0 0022UF 20 50V CAP FXD ELCTLT 2 7UF 10 15V CAP FXD CER 01 0 0 80 20 150 CAP FXD MTLZD 0 01UF 1076 63V CAP ELCTLT 2 2UF 20 20V ELCTLT 2 7UF 20 50 CAP FXD ELCTLT 1UF 206 35V CAP FXD MTLZD 1 0UF 10 50V FXD E
200. 295 MICROCKT LINEAR DUAL BI FET OPNL AMPL 01295 MICROCKT DGTL ZERO LOGIC 80009 MICROCKT DGTL A D CONVERTER 80009 RBIAFXESOK1 021501 3386F T04 102 5033ED16K50F NTR25J EO1K3 CEAD13301F 5033ED3K48F CEAD 13701F 5033 04 420 CEAD31600F 5033 04 020 NTR2SJ EO1K5 CEAD43200F NTR25JE01KO NTR25J E 20K 5043CX430R0J 5043CX240R0J GF126 0028 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0573 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 N7402 NB OR 155 0021 01 SN74LS393NP3 SN74LS393NDS N7402 NB OR FB SN74LS33NP3 155 0017 00 SN74LS74ANP3 155 0015 01 155 0014 01 SN74LS147NP3 155 0015 01 SN74LS393NP3 SN74LS393NDS 160 2997 00 SN74LS273NP3 TLO72CP 155 0018 00 155 0014 01 7 99 Replaceable Electrical Parts 7904 Tektronix Serial Assembly No Mfr Component No Part No Effective Dscont Name amp Description Code Mfr Part No A15A1U2246 156 1177 01 B030000 MICROCKT DGTL STET LINE PRIORITY ENCODER 01295 SN74LS147NP3 A15A1U2250 156 0032 03 010100 B029999 MICROCKT OGTL 4 BIT BINARY COUNTER 01295 5 7493 3 AL5A1U2251 156 0730 02 8030000 MICROCKT DGTL QUAD 2 INP NOR BFR SCRN 01295 SN74LS33NP3 A15A1U2257 156 1191 00 8 030000 MICROCKT LINEAR DUAL BI FET OPNL AMPL 01295 TLO72CP A15A1U2260 155 0019 00 80101
201. 3 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 0608 00 131 0608 00 131 0608 00 131 0608 00 131 0608 00 131 0808 00 131 0608 00 131 0608 00 131 0589 00 131 0589 00 131 0608 00 Serial Assembly No Effective _ Dscont 8010100 8010939 8010940 031870 8031871 8010100 8031870 8031871 8010100 8010939 8010940 8010100 8010939 8010940 Name amp Description CIRCUIT BD ASSY MAIN INTERFACE CIRCUIT BD ASSY MAIN INTERFACE CIRCUIT ASSY MAIN INTFC CAP FXD ELCTLT LOQUF 50 10 25V FXD ELCTLT 220UF 50 20 25V CAP FXD PLASTIC 0 O1UF 10 100V CAP FXD ELCTLT LOOUF 50 10 25V CAP FXD PLASTIC 0 O1UF 10 100V CAP ELCTLT 2QUF 50 1075 100V CAP ELCTLT 22UF 50 10 100V FXD ELCTLT 10UF 50 10 100V CAP FXD ELCTLT 22UF 50 10 100V ELCTLT 100UF 50 10 25V CAP FXD CER DI 2 7PF 0 25PF 500V CAP FXD CER D1 0 1UF 20 50 CAP FXD CER DI 0 1UF 2075 50V SEMICOND DVC DI 5W S1 30V 150 30V 00 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 SEMICOND DVC D1 SW SI 30V 150MA 30V D0 35 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 CONN RCPT ELEC CKT BD 38 76 CONTACT CONN RCPT ELEC CKT 8D 38 76 CONTACT CONN RCPT ELEC CKT 80 38
202. 3 036 QUANTITY OF 5 21 83 131 0608 00 010100 8010229 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 2 21 83 131 0589 00 010220 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ 22520 48283 029 QUANTITY OF 2 A21P132 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 02365 QUANTITY OF 10 821032 151 0190 05 TRANSISTOR SELECTED 243904 80000 151 0190 05 21036 151 0223 03 TRANSISTOR NPN SI 80000 151 0223 03 21039 151 0190 05 TRANSISTOR SELECTED 283904 80000 151 0190 05 801046 151 0223 03 TRANSISTOR NPN SI 80009 151 0223 03 21050 151 0190 05 TRANSISTOR SELECTED 2N3904 80008 151 0190 05 21067 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 A21068 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 821077 151 0443 02 TRANSISTOR SELECTED 80009 151 0443 02 A21Q83 151 0444 01 8010100 B010140 TRANSISTOR NPN ST SEL 80009 151 0444 01 21083 151 0444 03 8010141 TRANSISTOR NPN 51 TO 92 SCREENED TK0271 151 0444 00 210113 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 A210122 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 A210127 151 0427 00 TRANSISTOR NPN SI TO 92 07263 S39287 210132 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 A210143 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 210162 151 0220 05 TRANSISTOR SCREENED 80009 151 0220 05 210166 151 0434 01 TRANSISTOR SELECTED 04713 SS7144H 210167 151 0434 01 TRANSISTOR SELECTED 04713 557144 210173 151 0270 03 TRA
203. 30 Set the test oscilloscope for a vertical deflection factor of about 1 volt division and a horizontal sweep rate of 2 milliseconds division Connect the 7904A power cord plug to the variable transformer which is set for 0 volt Turn the 7904A on and slowly increase the variable autotransformer output to about 60 volts Check for a burst waveform on the test oscilloscope similar to that shown in Fig 4 6 NOTE The burst waveform indicates that the inverter circuit is attempting to start If no burst waveform occurs proceed to part 6 if a burst waveform is obtained proceed to part 5 1988 103 Figure 4 6 Current waveform of A23T30 showing burst operation at line voltage of about 60 voits 5 If burst waveform was obtained in part 4 above check for stable inverter operation when the line input voltage is increased to about 85 volts Figure 4 7 shows the current waveform at A23T30 for normal inverter operation at a line source of 115 volts NOTE The test oscilloscope horizontal sweep rate has been changed to about 50 microseconds division for Fig 4 7 If no burst waveform occurred in part 4 repeat part 1 of this step Then remove the current probe from the 7904A and the test oscilloscope Connect a 10X voltage probe from the test oscilloscope to TP34 on the A23 Power Supply inverter board Assuming that access to the A23 Power Supply Inverter circuit board has previously been gained remove the line inverter
204. 31433 330 105 5 5 21 10 281 0773 00 FXD CER 01 0 010 10 100 04222 2 21 11 290 0539 00 ELCT PEAZUF 20 20V 05397 T110C476MO20AS A21C12 281 0773 00 CAP FXD CER 01 0 010 10 100V 04222 201 103 21 13 281 0773 00 DI 0 01UF 10 00V 04222 201 103 A21C76 283 0001 00 01 0 0050 100 0 500V 59821 2D0H61L502P A21C79 283 0001 00 01 0 OOSUF 100 0 500V 59821 200 611502 21683 281 0773 00 01 0 01UF 1025 100V 04222 201 103 A21C101 281 0611 00 CAP CER DI 2 7PF 0 25PF 200V 52763 2RDPLZOO7 2P70CC A21C113 281 0773 00 CER DI 0 01UF 1075 100V 04222 201 103 A21C123 281 0773 00 DI 0 01UF 1075 100V 04222 201 103 A21C150 281 0118 00 010100 5021636 CAP VAR MICA D1 8 90PF 175V 52769 65 231 A21C150 281 0253 00 B021637 CAP VAR PLASTIC 10 180PF 100V 52769 GZC 18100 A21C151 281 0550 00 010100 B021636 CAP FXD CER 01 120 10 500 52763 2RDPLZ007 120PMO 21 151 281 0765 00 8021637 01 100 5 100 04222 MALOIALOIJAA A21C155 281 0118 00 010100 8021636 CAP VAR MICA D1 8 90PF 175V 52769 65 231 A21C155 281 0253 00 021637 CAP VAR PLASTIC 10 180PF 100V 52769 GZC 18100 A21C156 281 0584 00 010100 B021636 01 100 5 500
205. 315 0393 00 RES FXD FiLM 39K 5 0 258 57668 252 39 0 Al5AIR2137 315 0752 00 RES FILM 7 5K OKM 5 0 25W 5 668 NTR25 EQ7K5 A15AIR2139 315 0242 00 RES FILM 2 4K 5 0 25 57668 NTR25J E02K4 A15A1R2140 315 0103 00 8030000 RES FILM 10K 0HM 575 0 25W 19701 5043CX10K00J AL5A1R2141 315 0102 00 8030000 RES F LM 1K 5 0 25 57668 25 01 0 REV JUL 1987 Tektronix _ Serial Assembly No Replaceable Electrical Parts 7904A 7 35 Replaceable Electrical Parts 7904 t No ALSAIR2144 15 182146 15 182148 15 182150 2150 AL5AIR2151 15 182151 2152 15 182153 A15A1R2153 15 162154 15 162155 ALSAIR2155 AL5AIR2157 A15AIR2157 15 182158 15 1 2161 15 182162 AlSAIR2163 AiSAiR2165 A1SA1R2166 15 1 2167 A15AIR2169 A15A1R2170 AlSA1R2171 1 1 2173 A15A1R2174 1 1 2175 15 1 2177 15 1 2178 15 1 2179 15 1 2181 A15ATR2182 15 182182 15 182183 15 182183 15 182184 15 1 2185 15 182187 ALSAIR2191 A15AIR2191 15 182192 15 1 2192 A15A1R2193 15 1 2193 15 1 2194 15 182194 Al5AIR2196 ALSAIR2Z196 A15A1R2197 ALSAIR2197 15 182198 A15A1R2198 154182199 15 182201 15 182201 15 182202 15 182202 7 36 Tektronix Part 315 0104 00 315 0152 00 315 0103 00 321 0403 00 315 0183 00 321 0372 00 315 0362 0
206. 315 0512 00 315 0753 00 315 0201 00 315 0562 00 315 0224 00 315 0123 00 315 0301 00 315 0470 00 315 0102 00 315 0202 00 Serial Assembly No Effective _ Dscont 8010100 021705 8010100 8010100 8010100 8010100 8010100 010100 8031833 8010100 8031833 8010100 8031833 8010100 8031833 8021704 8031832 8031832 8031832 8031832 031832 8031832 8031832 8031832 8031832 Replaceable Electrical Parts 7904 Name amp Description SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 SEMICOND DVC DI SIG SI 225V 0 2A 00 7 SEMICOND DVC DI SIG 51 225V 0 2A D0 7 SEMICOND DVC DI S1G SI 225V 0 2A DO 7 SEMICOND DVC Di SIG ST 225V 0 2A DO 7 SEMICOND DVC D1 516 S1 225V 0 2A 00 7 SEMICOND DVC DI SIG SI 225V 0 2A 00 7 SEMICOND 01 516 51 225 0 2 00 7 SEMICOND DVC DI RECT S 600V 0 5A SEMICOND DVC DI RECT SI 6007 0 5 SEMICOND DVC DI RECT SI 600V 0 5A SEMICOND DVC DI RECT S1 600V 0 5A SEMICOND DVC DI RECT SI 500V 12A SEMICOND DVC DI RECT SI 500V 12A SEMICOND DVC DI RECT ST 500V 12A SEMICOND DVC DI RECT S1 500V 12A Mfr Code Mfr Part No 03508 07263 07263 07263 07263 07263 07263 07263 25403 25403 25403 25403 80009 80009 80009 80009 04713 DA2527 144152 FDH5004 FDH5004 FDH5004 FDH5004 FDH5004 FOHS004 FDH5004 960 OR BYV95C BYV96D OR BYV95C BYV96D OR BYV9SC BYV96D OR BYV95C 152 0397 00 152 0397 00 152 0397 00 152 0397 00 SD241
207. 31767 amp Above REV NOV 1985 4 Time Base F2 CHECK READOUT MODES NOTE First perform step F1 then proceed F2 SETUP CONDITIONS 7904A Controls HORIZONTAL MODE Ampiifier 5 amp 5 Test Equipmeni Controis Time Base Sweep Rate Triggering 4593 428 Set the READOUT INTENSITY control for a visible display CHECK set the time base to several sweep rates throughout its range and check that the readout characters are displayed Set the READOUT GATE EXT button to GATE pressed in and set the READOUT INTENSITY contro to PULSED Set the OUTPUT GATE button to A Set the READOUT PRESET control for a visible readout display Set the time base for a free running not triggered sweep at a rate of 0 2 second division 5 31 Checks and Adjustment 7904A Part Performance Check 5 32 CHECK that the readout characters are blanked out while the sweep is running and are displayed immediately after the end of the sweep each character encoded by the plug in units is displayed only once for each sweep Set the READOUT GATE EXT button to EXT released i CHECK press the READOUT MAN pushbutton and notice that one frame of readout is displayed This completes the Part Procedure i Performance Check Checks 7904 PART II ADJUSTMENT AND PERFORMANCE CHECK The following procedure Part il Adjustment and Performance Check pro
208. 3508 03508 93508 22526 04713 02735 19701 57668 19701 01121 19701 19701 57668 Mfr Part No 670 4641 00 1403001 0 5 1 ECE A100V10L DA2527 1N4152 042527 1N4152 DA2527 184152 042527 184152 DA2527 1N4152 DA2527 1N4152 48283 036 51898 89164 5053CX27 0R0J NTR25J E47EQ 5053 270 02 5265 5043ED1K210F 5043ED3KO010F RB14FXE 16E5 REV JUL 1987 Tektronix t No Part No 12 520 0283 01 12 15 290 0628 00 12 17 290 0628 00 A12C37 285 0938 00 12 154 290 0898 00 Al2F10 159 0017 00 Al2FL10 119 0420 00 A12137 108 0761 00 12028 151 0656 00 12034 151 0632 00 12040 151 0632 00 12058 151 0657 00 12074 151 0656 00 12094 151 0657 00 120122 151 0349 00 A120126 151 0477 01 Al2R6 303 0105 00 12512 260 1300 00 12599 260 0450 00 Al2T110 120 1183 00 REV JUL 1987 Serial Assembly No Effective Dscont Replaceable Electrical Parts 7904A Code Mfr Part No Mfr Name amp Description POWER SUPPLY LOW VOLTAGE 80009 INCLUDES 12 422 23 ASSEMBLIES CAP ELCTLT 950UF 50 10 200V 56289 CAP ELCTLT 950UF 50 1075 200V 56289 CAP PLASTIC 0 O3UF 5 900V 50558 CAP ELCTLT 2600UF 75 10 35V 56289 FUSE CARTRIDGE 4A 3AG 250V FAST BLOW 71400 FILTER RFI 6A 250VAC 400HZ 02777 COIL RF FIXED 1 54937 TRANSISTOR NPN SI TO 220 02735 TRANSISTOR NPN SILICON TO 220 04713 TRANSISTOR
209. 4 00 A2R2017 315 0622 00 A2R2018 315 0303 00 A2R2019 321 0193 00 A2R2020 311 1375 00 A2R2025 311 1372 00 A2R2035 311 1972 00 252005 260 1208 00 REV JUL 1987 Serial Assembly No Effective Dscont Replaceable Electrical Parts 7904 Name amp Description CIRCUIT BD ASSY DISPLAY CONTROLLER SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 SEMICOND DVC D1 5W 1 30V 150MA 30V 00 35 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 4 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 7 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 9 RES VAR NONW PNL 2 5M OHM 20 0 75 W RES FXD FILM 6 2K OHM 5 0 25W RES FXD FILM 30K OHM 5X 0 25M RES FXD FILM 1K ORM 125 0 1254 TC TO RES VAR NONWW PNL LOK OHM 1W RES VAR NONW PNL 100K OHM 0 54 RES FXD FILM 150 OHM 515 0 25W RES FXD FILM 6 2K 5 0 25W RES FXD FILM 30K 5 0 25 RES FILM 1K OHM 15 0 125W TC TO RES VAR NONWH PNL LOK OHM IW RES VAR NONWW PNL 100K OHM 0 SW RES VAR NONW PNL 2K OHM 10 2 0 W SWITCH PUSH DPDT 28VDC PUSH PUSH Mfr Code 80009 03508 03508 22526 22526 22526 01121 19701 19701 19701 01121 01121 57668 19701 19701 19701 01121 01121 01121 31918 Mfr Part 670 5227 01 2527 1N4152 DA2527 184152 48283 036 48283 036 48283 036 73M1G040L255M 5043CX6K200J 5043CX30K00J 5033ED1 KOOF 73M1G040L103M 73
210. 45 TK1345 TK2042 TK1345 22526 22526 22526 22526 22526 22526 04713 03508 80009 80009 80009 80009 80009 80009 80009 80009 57668 57668 57668 57668 57668 57668 57668 57668 57658 57568 ORDER BY DESCR ORDER BY DESCR 108 0680 00 108 0680 00 ORDER BY DESCR 108 0556 00 48283 036 48283 029 48283 036 48283 036 48283 036 48283 036 ST898 X16E3616 151 0190 05 151 0190 00 151 0190 05 151 0190 00 151 0188 03 151 0188 00 151 0188 03 151 0188 00 NTR25J EO5K1 NTR25J E75K0 NTR25J E200E 252 05 6 NTR25J E220K NTR25J E12KO0 NTR25J E300E NTR25J E47EQ NTR2SJEO KO 25 2K 7 23 Replaceabie Electrical Parts 7904 Tektronix t No Part No AL2A1R67 315 0154 00 AL2A1R70 315 0560 00 12 1 71 315 0560 00 AL2A1R74 321 0346 00 AL2A1R80 315 0471 00 12 1881 321 0334 00 12 1 82 321 0340 00 12 1883 321 0193 00 12 1684 321 0005 00 12 1 86 321 0284 00 A12A1R87 321 0283 00 12 1 88 315 0122 00 12 1 90 315 0272 00 12 1 92 315 0105 00 12 1893 311 1239 00 12 1893 311 2273 00 12 1894 315 0203 00 12 1895 321 0419 00 12 18120 315 0150 00 12 18121 315 0101 00 12 18127 301 0391 00 12 18161 315 0473 00 12 16162 315 0472 00 12 16170 315 0100 00 12 18171 315 0274 00 12418172 315 0474 00 12 18173 315 0272 00 12 18174 315 0182 00 12 18175 315 0203 00 12 1 177 315 0203 00 12 18179 315 0472 00 12
211. 4593 423 Set the signal standardizer Amplitude and Position controls so the display is exactly two divisions in amplitude in the center of the graticule area CHECK position the two division display vertically and check for not more than 0 1 division of compression or expansion anywhere within the graticule area Checks and Adjustment 7904A Part i Performance Check E4 CHECK VERTICAL AMPLIFIER 500 MHz GAIN NOTE If the preceding step was not performed first perform step E1 then proceed E4 SETUP CONDITIONS 7904A Controls VERTICAL MODE High Frequency Sine Wave Generator ex d E 9 S 3 Time CW in 2X Attenuator and input 3 50504 Output Head Test Equipment Controls Time Base Sweep 0 1 ms div Triggering Auto AC External Signal Standardi Vert or Horiz Freg Resp High Frequency Sine Wave Generator Reference Frequency 4593 424 Set the signal standardizer Amplitude control fully clockwise Set the high frequency sine wave generator for a 10 division display at the reference frequency between 6 and 50 megahertz centered on the graticule To obtain a 10 division display first obtain an eight division display then vertically position the display one division down and increase the output amplitude of the sine wave generator so that the top of the display reaches the top of the graticule Set the signal
212. 4844 321 0085 00 RES FXD FILM 75 0HM 12 0 1254 TC TO 57668 CRBIAEXE 75 OM 14 442 321 0202 00 RES FXD 1 24 OHM 1 0 125W TC TO 24545 5501241 7 30 REV JUL 1987 ent No Part No Al4R443 322 0111 00 148444 322 0170 00 148445 321 0202 00 148446 321 0147 00 146447 315 0103 00 148448 321 0155 00 Al4R451 321 0218 00 148452 321 0242 00 Al4R454 315 0102 00 14 455 311 1236 00 148456 321 0062 00 148462 322 0151 00 Al4R464 321 0201 00 148465 321 0285 00 A14R473 322 0239 00 148474 311 1248 00 AL4R476 317 0510 00 Ai4R477 317 0510 00 148478 322 0085 00 148479 311 1936 00 148480 311 1237 00 Al4R481 321 0179 00 148482 321 0182 00 Al4R483 317 0200 00 Ai4R484 315 0510 00 Al4R485 311 1936 00 148486 325 0026 00 A14R490 311 1037 00 Al4R491 321 0179 00 14 492 321 0182 00 148493 317 0200 00 146494 315 0510 00 A14R495 322 0145 00 14 496 325 0026 00 148497 322 0175 00 8148498 321 0143 00 148499 315 0510 00 Ai4U232 155 0173 05 A14U252 156 0158 00 A14U274 155 0175 05 A14U402 156 0730 02 A14U432 155 0173 05 A14U452 156 0158 00 A14U474 155 0175 05 140492 155 0175 05 A14VR237 153 0087 00 AL4VR247 153 0067 00 AL4VR437 153 0067 00 14 8447 153 0067 00 REV JUL 1987 Serial Assembly No Effective Dscont Replaceable Electrical Parts 79044 amp Description RES FXD FILM 140 OHM 125 0 25W TC TO RES FILM 576
213. 493 670 4777 20 SR302E1057AATR SRSOZELOSZAATR SR302E105ZAATR 58302 1057 10 1001 0155 2010 0 2RDPLZOO7 39POJC SR302E1057AATR 2RDPLZOO7 39POJC eRDPLZOO7 68POKU 831 000 25E0471J 2RDPLZ007 33POKE 2RDPLZ007 33 831 000 25E0471J 0155 131 0 2 7007 39POJC 2RDPLZ007 39PQJC D103Z40Z5UJDCEX 2RDPLZOO7170PJK 2RDPLZOO7170PJK C330C104MSU1CA 58302 1057 831 610 Y5UO102P SR302E1057AATR 855 535U2J101J FDH5004 5082 2672 DA2527 1N4152 DA2527 10152 DA2527 184152 2527 1N4152 DA2527 1N4152 DA2527 1N4152 DA2527 184152 DA2527 1N4152 DA2527 1N4152 DA2527 144152 DA2527 1N4152 DA2527 1N4152 FD7003 DA2527 1N4152 DA2527 1N4152 DA2527 1N4152 6866 152 0664 00 5866 DA2527 184152 DA2527 144152 145817 042527 144152 2527 184152 DA2527 184152 145817 131 1003 00 B6310 1 6310 1 B6310 1 7 25 Replaceable Electrical Parts 7904 Tektronix t No Part No A13L4304 108 0245 00 A13L4317 108 0245 00 131 4342 108 0245 00 A13L4344 108 0245 00 A13LRA338 108 0543 00 AL3LR4359 108 0543 00 A13LRA368 108 0543 00 13184412 108 0543 00 1304336 151 0198 00 1304364 151 0198 00 1304374 151 0188 00 A1304382 151 0192 00 A1304392 151 0192 00 A1304424 151 0192 00 1304432 151 0223 00 81304438 151 0192 00 1304442 151 0192 00 A1304448 151 0216 00 1304456 151 1022 00 81304462 151 0192 00 41304468 151 0192 00 81304480 151
214. 5 182217 321 0425 00 8 030000 RES FILM 261K OHM 125 0 1254 0 07716 CEAD26102F A15A1R2218 321 0396 00 030000 RES FILM 130K OHM 15 0 1254 TC TO 07716 CEAD13002F 15 182219 315 0751 00 010100 029999 RES FILM 750 5 0 25 57668 NTR25J E750t A15A1R2220 321 0299 00 8010100 029999 RES FILM 12 7 OHM 1 0 125W TC TO 19701 5033 012 70 15 182221 321 0212 00 010100 8029999 RES FILM 1 58K 1 0 125 70 19701 5033 01 58 15 182221 315 0752 00 8030000 RES FXD FILM 7 5K OHM 5 0 25W 57668 252 07 5 15 182222 315 0133 00 030000 RES FILM 13K 52 0 250 19701 5043CX13K00J A15AIR2223 315 0124 00 8030000 RES FILM 120K OHM 5 0 250 19701 5043 120 0 A15AIR2224 315 0751 00 8030000 RES FILM 750 OHM 5 0 25W 57668 NTR25J E750E 15 182225 321 0299 00 8030000 RES FILM 12 7K OHM 175 0 1250 TC TO 19701 5033ED12K70F 15 182226 315 0222 00 010100 029999 RES FXD FILM 2 2K OHM 5 0 258 57668 NTR25J EO2K2 A15A1R2226 321 0212 00 8030000 RES FILM 1 58K 12 0 1254 TC 70 19701 5033 01 58 15 182227 321 0268 00 8010100 8029999 RES FXD FILM 6 04K OHM 12 0 125W TC TO 19701 5043ED6KO40F ALSAIR2227 315 0152 00 8030000 RES FXD FILM 1 5K OHM 526 0 25W 57668 NTR25J EO1K5 A15A1R2228 321 0210 00 8010100 8029999 RES FILM 1 50K OHM 125 0 125W TC
215. 5 0472 03 A20R86 315 0472 03 A20R87 315 0472 03 A20R89 315 0331 03 20891 315 0101 03 20892 308 0058 00 A20R93 315 0104 03 A20R103 315 0100 02 A20R104 301 0101 03 208112 315 0136 01 A20R113 315 0203 02 4208115 311 1285 00 2 116 321 0430 00 208119 301 0102 03 A20R122 315 0474 00 208124 315 0331 03 208126 315 0681 00 208127 315 0332 00 A20R128 301 0623 02 A20R129 315 0150 00 A20R143 311 1287 00 A20R154 321 0271 00 REV JUL 1987 Serial Assembly No Effective _ Dscont Replaceable Electrical Parts 7904A Name amp Description LAMP GLOW 90V 0 AID T WIRE LD LAMP GLOW 90V MAX 0 ATD T WIRE LD TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 10 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ QUANTITY OF 5 TERMINAL PIN 0 46 L X 0 025 SQ BRZ QUANTITY OF 4 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 2 TERMINAL PIN 0 365 L X 0 025 BRZ 610 PL QUANTITY OF 5 TRANSISTOR SELECTED RES W 20 5 5 RES FXO CMPSN 2 7K OHM 54 0 SW RES FXD CMPSN 10 OHM 5 0 25W RES CMPSN 4 7K OHM 5 0 25W RES FXD CMPSN 4 7K OHM 525 0 254 RES FXD FILM 1 5M OHM 54 0 SW RES FXD FILM 1 5M OHM 5 5 0 Sw RES FXD CMPSN 100K OHM 55 0 254 RES FXD CMPSN 18K OHM 5 0 25W RES FXD CMPSN 22 M OHM 57 0 254 RES FXD CMPSN 2K OHM 5 5 0 25M RES CMPSN 100K 5 0 25 RES FXD CMPSN 1M OHM 54 0 25W RES NTWK FXD F
216. 52 0423 00 SEMICOND DVC DI RECT SI 400V M176A 04713 1N5000 A22CR148 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V DO 35 03508 DA2527 184152 A22P82 131 0589 00 TERMINAL PIN 0 46 L X 0 025 SQ BRZ 22526 48283 029 QUANTITY OF 10 A22P83 131 0589 00 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ 22506 48283 029 QUANTITY OF 8 A22P90 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 2 22022 151 0350 00 TRANSISTOR PNP ST T0 92 04713 5 56700 22034 151 0103 00 TRANSISTOR NPN SI TO 5 04713 SMI307 22038 151 0134 00 TRANSISTOR PNP SI 70 39 04713 5 3195 22052 151 0347 00 TRANSISTOR NPN ST 70 92 04713 5 57951 A22Q68 151 0347 00 TRANSISTOR NPN SI 0 92 04713 5 57951 22088 151 0342 00 TRANSISTOR PNP ST TO S2 07263 5035928 7 56 REV JUL 1987 ent No 220118 220144 220148 2261 A22R2 A22R3 2264 2265 82288 22810 A2 R12 A22R13 422614 22815 A22R16 A22R17 A22Rel A22R22 A22R24 A22R25 A22R26 A22R27 A22R28 A22R32 A22R34 22 36 A22R37 A22R38 A22R42 2244 2245 A22R46 A22R47 A22R51 22 52 AZ2R54 A22R55 A22R56 A22R57 A22RS8 A22R61 A22R62 A22R63 22567 AZ2R68 A22R69 A22R73 A22R7A A22R75 A22R76 2277 A22R80 22881 2282 22 83 A22R87 A22R88 A22R93 REV JUL 1987 Tektronix Part No 151 0302 00 151 0190 05 151 0373 00 321 0369 00 321 0386 00 321 0336 00 321 0290 00 321 0319 00 315 0332 00 323 0
217. 5397 03508 03508 ECE B25V100L 2RDPLZ007 2P70CC C330C1 04MSUICA C330C1 04MSUICA DA2527 1N4152 DA2527 184152 DA2527 144152 DA2527 1N4152 DA2527 184152 DA2527 1N4152 DA2527 1N4152 131 0767 10 03508 03508 03508 03508 03508 80009 A a 80009 80009 80009 80009 80009 80009 131 0767 10 131 0787 10 131 0767 10 131 1003 00 131 1003 00 131 1003 00 80009 80009 80009 80009 80009 80009 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 131 1003 00 80009 20526 131 1003 00 48283 036 20526 48283 036 22525 48083 036 20526 48283 036 22526 48283 036 20506 48283 036 22526 48283 036 22526 48283 036 22506 48283 029 22526 48283 029 22526 48283 036 REV JUL 1987 Tektronix ent No Part No A6P85 131 0608 00 87 131 0608 00 131 0608 00 6075 151 0192 00 6 amp 20 315 0470 00 6822 321 0260 00 ABR23 321 0260 00 5840 315 0470 00 42 321 0250 00 ASR43 321 0260 00 6 52 315 0472 00 315 0470 00 AGREG 315 0302 00 A6R67 315 0202 00 ABR71 315 0202 00 A6R74 315 0202 00 46875 315 0102 00 6 80 315 0470 00 ABRB83 315 0243 00 A6R85 315 0105 00 AGREG 315 0152 00 6 87 315 0103 00 48 88 315 0152 00 ABROD 315 0202 00 AGRS1 315 0132 00 AGR92 315 0470 00 A6R93 321 0231 00 6 94 323 0150 00 ABRS5 321 0231 00 A6R97 315 0132 00 AGRS9 315 0132 00 REV JUL 1987 Serial Assembly No Effective Dscont Replaceable Electrical
218. 57668 19701 57668 57668 07716 19701 19701 57568 19701 91637 01121 01121 57568 19701 91637 19701 57668 19701 19701 19701 91637 01121 57668 19701 19701 01121 19701 01121 14193 80009 80009 80009 80009 80009 80009 80009 80009 80009 15238 04713 NTR25JEO1KO 50430X30R00J NTR25J EO4K3 5043 22800 5043CX30R00J NTR25JEQ1KO 5043CX22R00J CB 4765 CECD800ROD 3329H 648 102 0800 00 43F1K5 43F1K5 CMF551 16G47R50F NTR25JEO1KO 5033ED1K330F CEAD54900C 5033 5 230 NTR25J E910E 5043CX8K200J NTR25J E750E NTR25J EO3K3 CEAD71500F 5043ED7K320F 5033EDIK330F NTR25JEO1K0 5043 27 002 CMF55116647R50F CB 4765 583325 NTR25J E270E 5043 10 002 MFF1226G24901F 5053CX56K00J 252 200 5043CX15R00J 5033 01 82 5033ED1K330F MFF1226G24901F GB2735 NTR25J E200 5043CX10RROOJ 90430X27R00J 082725 5053 33 002 682225 1815 500 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 25406 52835009 13 7 67 Replaceable Electrical Parts 7904 Tektronix _ Serial Assembly No Mfr Component No Part No Effective Dscont Name amp Description Code Mfr Part No A29 670 8059 00 CIRCUIT BD ASSY HORIZONTAL INTERCONNECT 80009 670 8059 00 A29C606 281 0505 00 CAP CER 01 12 10 500 59660 301 000 060 120 A29C622 281 0505 00 01 12 10 500
219. 579 00 5 367 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A5TP368 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 A5TP369 214 0579 00 TERM TEST POINT BRS CD PL 80009 214 0579 00 50352 156 0384 02 MICROCKT DGTL QUAD 2 INP NAND GATE SCRN 07263 74LSOSPCQR A5U362 156 0386 02 MICROCKT DGTL TRIPLE 3 NAND GATE SCRN 07263 741510 A5U364 156 0382 02 MICROCKT DGTL QUAD 2 INP NAND GATE BURN 18324 N74LSOONB 51 366 156 0382 02 MICROCKT DGTL QUAD 2 INP NAND GATE BURN 18324 N74LSOONB A5U368 156 0722 02 MICROCKT DGTL TRIPLE 3 INP W OC OUT 01295 SN74LS12NP3 REV JUL 1987 7 13 Replaceable Electrical Parts 79044 AG A8C2 6 6 4 A6C5 6 6 ASCE A6C8 6 8 6 9 6 71 6 85 6 87 ABCRS2 AGCR71 ASCR81 AGCRB2 AGCR86 AGCR88 ABIL A6J2 624 A6J38 6239 46271 6 78 590 A6J91 6 92 293 6394 6499 2 A6P3 AGPS AGP65 AGP66 A6P67 A6P79 AGP80 6 82 AGP83 6 84 7 14 Tektronix t No Part No 670 4775 00 570 4775 01 670 4775 02 290 0747 00 290 0966 00 285 0674 00 290 0747 00 285 0674 00 290 0194 00 290 0969 00 290 0194 00 290 0969 00 290 0747 00 281 0547 00 283 0111 00 283 0111 00 152 0141 02 152 0141 02 152 0141 02 152 0141 02 152 0141 02 152 0141 02 152 0141 02 131 0767 10 131 0767 10 131 0767 10 131 0767 10 131 1003 00 131 1003 00 131 100
220. 59660 301 000 060 120 42905304 150 0097 00 LAMP INCAND 6 3V 0 2 87381 WIRE LEADS 92966 7381 2905305 150 0097 00 LAMP INCAND 6 3V 0 2A 7381 WIRE LEADS 92966 7381 2905306 150 0097 00 LAMP INCAND 6 3V 0 2A 27381 VIRE LEADS 92966 7381 A293126 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A293220 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 292226 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 29J320 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J602 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J612 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J614 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J616 131 1003 00 CONN RCPT ELEC CKT MT 3 PRONG 80009 131 1003 00 292620 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J624 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29J626 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A29P90 131 0589 00 TERMINAL PIN 0 46 L X 0 025 SQ BRZ 22526 48283 029 QUANTITY OF 6 A290400 151 0301 00 TRANSISTOR PNP ST TO 18 04713 51898 A290422 151 0302 00 TRANSISTOR NPN 51 TO 18 04713 51899 A290424 151 0302 00 TRANSISTOR NPN SI 70 18 04713 51899 A29R122 311 1227 00 RES VAR NONW SK OHM O SW 32997 3386 104 502 A29R506 321 1058 01 RES FXO F1LM 50 5 0 5 0 1259 TC TO 57668 RBl14 DX
221. 5A1C2180 281 0773 00 A15A1C2183 283 0032 00 A15A1C2183 281 0788 00 A15A1C2185 283 0004 00 A15A1C2185 281 0774 00 A15A1C2186 281 0773 00 A15A1C2187 281 0862 00 Ai5A1C2190 281 0773 00 AL5A1C2201 283 0114 00 15 1 2200 281 0773 00 A15A1C2203 281 0773 00 15 1 2204 281 0773 00 15 1 2211 281 0762 00 A15A1C2212 283 0656 00 A15A1C2213 283 0640 00 15 1 2214 283 0032 00 15 1 2221 281 0788 00 15 1 2239 281 0788 00 A15A1C2242 283 0000 00 A15A1C2243 281 0773 00 A15A1C2244 283 0004 00 15 1 2244 281 0774 00 A15A1C2245 281 0773 00 REV JUL 1987 Serial Assembly No Effective _ Dscont 8010100 8030000 B031801 B041952 8010100 8030000 B010100 B030000 8010100 8030000 8010100 030000 8010100 8030000 8030000 8010100 8030000 8010100 8030000 8030000 8010100 8041952 8010100 8030000 8030000 8030000 8010100 8030000 8030000 8030000 8030000 8010100 8030000 8010100 8030000 8030000 8030000 8030000 8030000 8030000 8030000 8030000 8030000 8030000 8030000 010100 030000 8030000 8010100 8030000 8010100 8030000 8030000 029999 8031800 8041951 8029999 8029999 8029999 8029999 8029999 8029999 8023999 8030000 029999 029999 8029999 8029999 8029999 8029999 029999 8029999 Replaceable Electrical Parts 7904A Name amp Description CIRCUIT BD ASSY READOUT PART OF 672 0572 XX CIRCUIT BD ASSY READOUT PART OF 672 0572 XX
222. 5V RES FXD FILM 2 2K OHM 525 0 25W RES FILM 10K OHM 54 0 25W RES FILM 820 0HM 54 0 25W RES FXD FILM 8 2K OHM 5 0 25W RES FXD FILM 1 3K OHM 5 0 25W RES FXD F1LM 270 OHM 5 0 25W RES FXD FILM OHM 5 0 254 RES FXD FILM 820 OHM 525 0 25M RES FXD FILM 10 2K OHM 12 0 1254 TC TO RES FXD FILM 3 57K OHM 1 0 125W TC TO RES FXD FILM 10 2K OHM 1 0 125W TC TO RES FXO FILM 3 57K OHM 1 0 125W TC TO RES FXD FILM 10 OHM 55 0 25W VES FXD F1LM 3 32K OHM 12 0 1254 TC T0 RES FILM 2 4K OHM 5 0 25 RES FXD FILM 5 1K OHM 5 0 25W RES FILM 5 IK 525 0 25M RES FXD FILM 150 QHM 54 0 25V RES FILM 3 32K OHM 125 0 1258 TC T0 RES FXO FILM 10K OHM 5 0 25W RES FXO FILM 1 33K 12 0 125W TC TO RES FXD FILM 510 OHM 5 0 25W RES FXD FILM 3 3K OHM 5 0 25W RES FILM 2 00K OHM 1 0 125W TC TO RES FILM 2 00K OHM 1 0 125W TC TO RES FILM 91K OHM 5 0 25W RES FXO FILM 200 OHM 5 0 25W RES FXO FILM 1 5 OHM 555 0 25W RES FXD FILM 20K OHM 5 0 25W RES FXD FILM 7 5K OHM 5 0 25W RES FXD FILM 100 OHM 5 0 25W RES FXD FILM 1K OHM 5 0 25W RES FXD FILM 20K OHM 5 0 25W RES FILM 1K OHM 5 0 258 RES FXD FILM 430 OHM 5 0 25W RES FILM 910 OHM 5 0 25W RES FILM 430 OHM 52 0 25W RES FXD FILM 2K OHM 5 0 25W
223. 6 volts more negative than the level at its base Then Q1 is forward biased and its emitter rapidly rises positive see Time T on wave forms Since C4314 cannot change its charge instantaneously the sudden change in voltage at the emitter of Q1 pulls the emitter of Q2 positive With Q2 reverse biased its collector rises positive to produce a positive output level at pin 14 Now conditions are reversed Since Q2 is reverse biased there is no current through it Therefore C4314 can begin to discharge through R4314 The emitter level of Q2 follows the discharge of C4314 until it reaches a level of about 0 6 volt more negative than its base Then Q2 is forward biased and its collector drops negative to reverse bias Q1 The level at pin 14 drops negative also to complete the cycle Once again C4314 begins to charge through R4312 R4313 to start the second cycle Two outputs are provided from this oscillator The Delay Ramp signal from the junction of R4312 R4313 is connected to the Vertical Chopped Blanking stage This signal has the same waveshape as the waveform at pin 13 its slope is determined by the divider ratio between R4312 R4313 A wide pulse train output is provided at pin 14 The frequency of this pulse train is determined by the overall RC relationship between C4314 R4312 3 15 Theory of Operation 7904A 2MHzFREE RUNNING _ OSCILLATOR 15 CLOCK A U4320 15V 8 1195 16 2314 2 Figure 3 3
224. 668 NTR25J E04K3 22 1 1 315 0822 00 RES FILM 8 2K OHM 52 0 25W 19701 5043CX8K200J A22R142 315 0103 00 RES FILM 10K 0HM 54 0 25W 19701 5043 10 002 A22R143 315 0243 00 RES FXD FILM 24K 0HM 525 0 25W 57668 NTR25 E24K0 A22R144 315 0562 00 RES FXD FILM 5 6K OHM 5 0 259 57668 NTR25J E05K6 A22R145 315 0221 00 RES 220 OHM 54 0 25W 57668 NTR25J E220E A22R148 308 0702 00 RES WW 0 33 OHM 5 2M 75042 BWH R3300J A22R152 301 0561 00 RES FILM 560 5 0 5 01121 5615 A22R156 301 0431 00 RES FXD FILM 430 5 0 5W 19701 50530X430R0J A22U15 156 0067 12 8010100 8010784 MICROCKT L INEAR OPERATIONAL AMPLIFIER 01295 UA741CJG A22U15 156 0067 01 8010785 8041970 MICROCKT LINEAR OPNL AMPL CHECKED 04713 1741 105 A22U15 156 0067 00 8041971 MICROCKT LINEAR OPNL AMPL SEL 04713 1741 A22U45 156 0067 12 010100 8010784 MICROCKT LINEAR OPERATIONAL AMPLIFIER 01295 74156 A22045 156 0067 01 8010785 B041970 MICROCKT LINEAR OPNL AMPL CHECKED 04713 1741 105 A22U45 156 0067 00 041971 MICROCKT LINEAR OPNL AMPL SEL 04713 1741 22064 156 0158 04 MICROCKT LINEAR DUAL OPNL AMPL 01295 MC1458JG A22U84 156 0158 04 MICROCKT LINEAR DUAL OPNL AMPL 01295 MCi458 G A22U114 156 0158 04 MICROCKT LINEAR DUAL AMPL 01295 145826 A22VR10 152 0217 00 SEMICOND DVC DI ZEN SI 8 2V 54 0 4W 00 7 04713 57620 221812 152 0212 00 SEMICOND DVC DT ZEN SI 9V
225. 70 4773 03 CIRCUIT BD ASSY MODE SWITCH 80008 670 4773 03 ASC324 283 0002 00 CAP CER DI 0 01UF 80 2055 500V 59821 D10374075ULADEG A5C325 283 0115 00 DI 47PF 5 200V 59821 2DDT60K470J A5C326 283 0002 00 DI 0 01UF 480 207 500V 59821 D10374025ULADEG A5C376 285 1006 00 CAP PLASTIC O 22UF 2 50V TK2038 285 1006 00 5 384 283 0115 00 CAP CER DI 47PF 5 200V 59821 200 60 470 5 386 283 0115 00 01 47 5 200 59821 2D0T60K470J ASCR342 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 DA2527 1N4152 ASCR362 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 1M4152 ABCR386 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 0 2527 1 4152 A5J301 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 451392 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 A5P302 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 10 A5P303 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 10 A5P304 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22506 48283 036 QUANTITY OF 5 ASP305 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 225206 48283 0236 QUANTITY OF 7 5 306 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 8 A5P308 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526
226. 713 07263 07263 12969 04713 12969 04713 07263 04713 12969 0213 25088 25088 TK1345 03508 04713 04713 04713 04713 04713 01121 14193 01121 01121 14193 01121 01121 01121 57668 01121 19701 19701 19701 57668 19701 670 6259 01 670 6259 02 388853125002032 61782 1 388853125002032 SR306E1047A 564 202 222 DHR17Z5U502M3KY 564 202 222 DHR17Z5U502M3KV TEK13 17 ULALHOLOTEA 855 535U22101J 564 202 222 DHR12Y55102M3KV ULALHOLOTEA SRS03C103MAA ECEA2CS4R7 604 1 RKBPC606 12 SR1977K 5 1977 FDH2161 FDH2161 6727 SR1977K 9727 SR1977K FDH2161 1N5817 6727 JH005 3011JA 81 230 1 230 108 0681 00 X13T520 SJE1946 SJE1946 5 57951 5 56700 5 1083 682701 SA31 6R80J 584731 681845 SA31 6R80J 084731 5651 GB 1541 NTR25J E470E 581005 S043CX22R00J 5043CX10K00J 5053CX20R00J NTR253 03K3 5053CX20R00J 7 59 Replaceable Electrical Parts 7904 Tektronix _ Serial Assembly Mfr Component No Part No Effective _ Dscont Name amp Description Code Mfr Part No A23R40 315 0220 00 RES FXO FILM 22 OHM 5 0 25W 19701 5043 22 002 A23R41 315 0753 00 RES FILM 75K 525 0 25W 57668 NTR25J E75K0 23842 315 0303 00 RES FILM 30K 5 0 258 19701 5043CX30K00J A23R43 315 0274 00 RES FILM 270K OHM 525 0 25W 57668 NTR25J E270K A23R44 315 0270 00 RES FILM
227. 9 80009 80009 80009 00779 881005 5033ED200RO0F CMF55116647R50F 5033 01 0 NTR25J E 100 5033 0200 CEAD13700F NTR25J E02K7 CECTO 7151F 3329P 1 58 102 5033ED200RO0F 252 01 0 5043 20 00 5033ED200ROF CEAD13700F NTR25J E 100 5043CX560R0J 3329P 158 251 NTR25J E270E NTR25J EO1K5 3329H L58 101 3329H L58 101 5043CX1M000J NTR25J E 100E NTR25J E680E NTR25J E390E 5043CX360R0J NTR25J EO3KO 684325 55116040201 5043ED68K10F 5043CX51R00J 5053CX4K700J 50530X4K700J CECTO 4992F 5033 04 990 CMF551166100ROF 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 131 1436 00 1 331677 4 7 55 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr t No Part No Effective Dscont Name amp Description Code Mfr Part No A22 670 5960 03 010100 B031870 CIRCUIT BD ASSY LOW VOLTAGE REGULATOR 80009 870 5960 03 A22 670 5960 04 031871 CIRCUIT 8D ASSY LV REGULATOR 80009 670 5960 04 A22C8 290 0778 00 CAP ELCTLT 50 10 50V NPLZD 54473 22 12 290 0778 00 CAP ELCTLT 1UF 50 10 50V NPLZD 54473 ECE ASON1 A22C13 283 0047 00 DI 270PF 55 500V 59660 083160475 02712 A22C15 281 0629 00 CAP FXD CER DI 33PF 54 600V 527863 2 0 17007 22 17 290 0778 00 ELCTLT 50 10 50V NPLZD 54473 5 A22C24 283 0110 00 C
228. 9 thus disabling the Inverter Start network while the instrument is on INVERTER The Inverter stage converts the dc voltage across C16 and Ci7 to a sine wave current to drive power transformer 7110 Once the Inverter has been started by the Inverter Start network transformer T30 provides feedback to the bases of Q34 and 040 to sustain oscillation These transistors operate at a forced beta of 4 due to the turns ratio of T30 Also T30 provides a 60 1 turn ratio center tapped winding for pre regulation and 3 60 fault protection shut down The Inverter Control stage short circuits one half of this winding to either delay the turn on of Q34 and 040 or to completely stop their switching action The switching action of Q34 and 040 generates a square wave voltage with an amplitude approximately equal to the dc voltage at the input to this stage The square wave voltage at the emitter of Q34 supplies the drive necessary to maintain a sine wave current in the series resonant network of L37 and C37 Diodes CR34 and CR41 provide paths for series resonant current when Q34 and 040 are held off for pre regulation To aid in understanding circuit operation Figure 3 24A shows a representation of the Inverter stage as a switch The three possible states of the Inverter are depicted by the three possible switch positions Q34 is on in position a Q40 is on in position c or both transistors are held off for pre regulation in position b In the
229. 928 GREENVILLE SC 29606 ELECTRONICS DIV 31918 SCHADOW INC 8081 WALLACE RD EDEN PRAIRIE MN 55343 7 2 REV JUL 1987 CROSS INDEX MFR CODE NUMBER TO MANUFACTURER Mfr Replaceable Electrical Parts 7904A CROSS INDEX CODE NUMBER TO MANUFACTURER Code Manufacturer Address City State Zip Code 32997 33095 44655 50434 50558 51406 51642 52306 52763 52769 54473 54937 55112 55292 55680 56289 57668 58854 59660 59821 60211 60705 71409 72982 73138 74970 75042 76493 77342 79727 80009 80031 82389 84411 91637 92966 0213 0271 TK1345 TK1450 TK2038 TK2042 BOURNS INC TRIMPOT DIV SPECTRUM CONTROL INC OHMITE MFG CO HEWLETT PACKARD CO OPTOELECTRONICS DIV ELECTRONIC CONCEPTS INC MURATA ERIE NORTH AMERICA INC GEORGIA OPERATIONS CENTRE ENGINEERING INC UNTTRODE CORP HIGH VOLTAGE DEVICES INC STETTNER ELECTRONICS INC SPRAGUE GOODMAN ELECTRONICS INC MATSUSHITA ELECTRIC CORP OF AMERICA DE YOUNG MANUFACTURING INC WESTLAKE CAPACITORS INC LEDCO DIV WILBRECHT ELECTRONICS INC NICHICON AMERICA CORP SPRAGUE ELECTRIC CO ROHM CORP GTE PRODUCTS CORP LIGHTING PRODUCTS GROUP TUSONIX INC CENTRALAB INC SUB NORTH AMERICAN PHILIPS CORP VOLTAGE MULTIPLIERS INC CERA MITE CORPORATION BUSSMANN MFG CO MCGRAW EDISION CO ERIE TECHNOLOGICAL PRODUCTS INC BECKMAN INSTRUMENTS INC HELIPOT DIV JOHNSON E F CO INTERNATIONAL RESISTIVE CO INC BELL INDUSTRIES INC M
230. 9701 57668 57568 57668 57668 19701 19701 19701 57668 57668 48283 036 48283 036 48283 036 5 58801 NTR25J E47E0 5033 04 990 5033 04 990 NTR25J E47E0 5033EDAKS80F 5033 04 990 NTR25J EO4K7 NTR25J E47E0 NTR25J EO3K0 NTR2SJ E 2K NTR25J E 2K NTR25J E 2K NTR25JEO1K0 NTR25J E47EO NTR25J E24K0 50430X1M000J NTR25J EO1K5 50430X10K00J NTR25J EO1K5 252 2K NTR25J EO1K3 NTR25 E47EQ 5033ED2K49F 5053RD453ROF 5033ED2K49F NTR2SJ EO1K3 NTR25J EO1K3 7 16 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr Component No Part No Effective _ Name amp Description Code Mfr Part No A7 670 8051 00 CIRCUIT BD ASSY FRONT PANEL DISPLAY 80009 670 8051 00 7 11 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A7P12 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A7P13 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL P 80009 131 1149 00 QUANTITY OF 2 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix _ Serial Assembly No Mfr Component No Part No Effective _ Dscont Name amp Description Code Mfr Part No A8 670 8051 00 CIRCUIT BD ASSY FRONT PANEL DISPLAY 80009 670 8051 00 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2 A8P12 131 1149 00 CONTACT ELEC CKT BD EDGE PH BRZ SIL PL 80009 131 1149 00 QUANTITY OF 2
231. 98 saturated with the HORIZONTAL MODE switch in ALT or CHOP Base current is provided from the 5 V supply on the mode switch board through either the ALT or CHOP switch contacts and through resistors R4486 and R4490 to the bases of Q4494 and R4498 Both A and B INTENSITY indicator lights are on When the HORIZONTAL MODE switch is set to A or B the voltage at the collector of Q4492 which is derived from the Display B Command signal controls the A and B INTENSITY lights as previously described TRIGGER SELECTOR The Trigger Selector circuit determines the source of the internal triggering signals connected to the A and B Horizontal compartments A schematic diagram of the Trigger Selector is given on Diagram 5 in Section 8 of this manual Diagram and Circuit Board Illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use these stage names to further identify portions of the circuitry on Diagram 5 A AND B TRIGGEH CHANNEL SWITCHES The operation of the A and B Trigger Channel Switch stages is similar Therefore only a discussion of the A Trigger Channel Switch is given Amplifier units installed in the vertical compartments provide a differential trigger signal to the mainframe These signals are terminated into 50 ohm power dividers The 50 ohm strip transmission line
232. 9RO0F A16R543 321 0085 00 RES FILM 46 4 OHM 1 0 125W TC TO 57668 RBIAFXE 4664 A16R547 321 0084 00 RES FXD FILM 73 2 OHM 1 0 125W TC TO 91637 CMF55116G 3R20F A16R548 323 0168 00 RES FILM 549 OHM 12 0 5W TC T0 19701 5053RD549R0F 168549 321 0010 00 RES FXD FILM 12 4 OHM 19 0 1254 TC TO 57668 RBi4FXE 1264 168550 323 0136 00 RES FXD FILM 255 OHM 1 0 5W TC TO 24546 NAG5D2550F A15R552 315 0512 00 RES FILM 5 1K OHM 52 0 25W 57668 NTR25J EOSKI 158555 315 0102 00 RES FILM 1K OHM 5 0 25W 57668 25 01 A16R556 321 0126 00 RES FILM 200 1 0 1254 1 0 19701 5033 020080 A16R557 321 0237 00 RES FXD FILM 2 87K OHM 1 0 125W TC TO 07716 CEAD 28700F A16R558 321 0126 00 RES FXD FILM 200 OHM 12 0 125W TC TO 19701 5033 0200 0 168559 317 0103 00 RES CHPSN 10K OHM 5 0125W 01121 881035 A16R801 321 0289 00 RES FILM 10 0K OHM 125 0 1258 TC TO 19701 5033ED10K0F A16R602 321 0289 00 RES FILM 10 0K OM 125 0 125W TC TO 19701 5033 0 168604 321 0335 00 RES FILM 30 1K 126 0 1250 TC TO 57668 RBL4FXE30Ki A16R605 321 0335 00 RES FILM 30 1K OHM 125 0 125W TC TO 5 668 RBi4FXEJOKi 168611 321 0414 00 RES FILM 200K OHM 125 0 1298 TC TO 07716 020002 168612 311 1214 00 RES VAR NONW TRMR 200K OHM 0 5W 32997 3386F T04 204 168613 315 0203 00 R
233. A horizontal unit is dispiayed The Display B Command is used in the following stages within the Logic circuit Horizontal Logic A and B Sweep Inhibit Z Axis Logic Vertical Binary and Trace Separation In addition it is connected to the following circuits elsewhere in the instrument to indicate which horizontal unit is to be displayed Main Interface A and B HORIZ plug in compartments Horizontal interface for horizontal channel selection The leveis on pins 3 4 7 and 10 of U4358 are determined by the HORIZONTAL MODE switch see diagram 2 A HI output level on one of four output lines indicates which horizontal mode has been selected The remaining lines are LO Horizontal Binary stage operates as follows for each 4 positions of the HORIZONTAL MODE switch refer to Table 3 7 for input output conditions 1 A MODE By setting the HORIZONTAL MODE switch to A the Display B Command is LO indicating to ail circuits that the A horizontal unit is to be displayed 3 11 Theory of Operation 7904A TABLE 3 6 Input Output Combinations for the Z Axis Logic Stage Hi MAX VOLTAGE OR CURRENT LO MIN VOLTAGE CURRENT VAR VARIABLE CURRENT 0 to 4 mA 9 va e e m j H VAR BINTENSITY OTHER COMBINATIONS HAS NO EFFECT A INTENSITY A INTENSITY VA INTENSIFIED VA NO OUTPUT TABLE 3 7 Input Output Combinations of the Horizontal Binary Stage ta
234. AMP INCAND 5V 0 06A 683 AGED amp SEL TERM FEEDTHRU 0 584 L X 0 625 OD BRS QUANTITY OF 3 CONN RCPT ELEC FEMALE CONN ELEC BNC FEMALE CONN RCPT ELEC FEMALE COIL TUBE DEFL TRACE ROTATOR COIL TUBE DEFL TRACE ROTATOR COIL TUBE DEFL TRACE ROTATOR COIL RF FIXED 25UH COIL TUBE DEFL TRACE ROTATOR COIL TUBE DEFL TRACE ROTATOR COIL RF FIXED 39NH COIL RF FIXED 39NH RES FXD FILM 2 175 OHM 2 33 7 OHM SWITCH PUSH DPST 15A 250VAC PUSH PUSH ELECTRON TUBE CRT P31 INT SC ELECTRON TUBE FINISHED T7900 31 2 ELECTRON TUBE CRT P31 INT SC OPTION 04 ONLY ELECTRON TUBE CRT P11 INT SC OPTION 13 ONLY ELECTRON TUBE CRT P11 INT SC OPTION 78 ONLY Mfr Code 59821 56289 56289 55292 58854 58854 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 TK1345 TK1345 80009 77342 80009 80009 80009 80009 80009 Mfr Part No D10324025UJDCEX 5020X2626035AA2B 5020 2620035 2 71320 03 6834515 683A515 131 0765 01 131 1315 01 131 1315 01 131 1315 01 108 0544 00 108 0544 01 108 0605 00 108 0337 00 108 0544 00 108 0605 00 108 0685 00 108 0685 00 307 0292 24 A9M1 762 5 3 154 0644 05 154 0893 05 154 0661 05 154 0661 09 154 0644 09 7 71
235. ANTITY OF 10 A15A1P2166 131 0608 00 TERMINAL P1N 0 365 L X 0 025 BRZ GLD PL 22526 48283 03565 7 34 REV JUL 1987 Mfr Canponent No Part No Fffective _ Dscont Name amp Description Code Mfr Part No QUANTITY OF 10 15 1 2171 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22506 48283 036 QUANTITY OF 10 15 1 2250 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 202506 48283 036 QUANTITY OF 10 1 102108 151 0223 00 TRANSISTOR NPN SI TO 92 04713 5 58026 15 102112 151 0221 00 TRANSISTOR PNP SI 70 92 80009 151 0221 00 A15A102131 151 0190 00 8030000 TRANSISTOR NPN ST 10 92 80009 151 0190 00 A15A102132 151 0190 00 8030000 8031800 TRANSISTOR S T0 92 80009 151 0190 00 A15A102132 151 0432 00 8031801 TRANSISTOR 51 0 106 04713 5 58512 15 102138 151 0188 00 TRANSISTOR PNP SI TO 92 80009 1 51 0188 00 15 102142 151 0190 00 8030000 TRANSISTOR NPN SI 10 92 80009 151 0190 00 15 102151 151 0190 00 030000 TRANSISTOR NPN SI TO 92 80009 151 0190 00 15 102152 151 0190 00 B030000 TRANSISTOR NPN SI T0 92 80009 151 0190 00 15 102153 151 0192 00 010100 8029909 TRANSISTOR SELECTED 04713 5 58801 15 102153 151 0190 00 030000 TRANSISTOR NPN ST TO 92 80009 151 0190 00 15 102159 151 0190 00 8010100 029999 TRANSISTOR NPN 51 TO 92 80009 151 0190 00 1 102181 151 0190 00 8030000 TRANSISTOR NPN ST 70 92 80009 151 0190 00 A15A102215 151 0232 00 8010100 B029999 TRAN
236. AP 21 0 005 80 20 150V 59660 855 547 5027 A22C36 281 0775 00 CAP 01 0 1UF 2025 50V 04222 MA205E104MAA A22C44 283 0067 00 D1 0 001UF 10 200V 59660 835 515 YSEO102K A22C45 281 0511 00 CAP 01 22 2 2 500V 52763 280 17007 22 22 47 290 0778 00 CAP FXD ELCTLT 50 10 50V NPLZD 54473 ECE ABONI A22C54 283 0100 00 D1 0 0047UF 10 200V 04222 SR306A472KAA A22C64 281 0540 00 CAP FXD CER DI 51PF 5 500V 59660 301 000U2J0510J A22C68 290 0420 00 CAP FXD ELCTLT 0 68UF 20 75V 05397 T110A684M075AS A22C69 283 0067 00 CAP FXD CER 01 0 001UF 10 200V 59660 835 515 YSEO102K A22C84 281 0629 00 CAP FXD CER DI 33PF 5 600V 52763 2RDPLZ007 A22C88 290 0420 00 FXD ELCTLT 0 68UF 20 75V 05397 T110A684M075AS A22C114 281 0605 00 CAP FXD CER DI 200PF 10 500V 59660 301000Y50201K A2 C156 290 0745 00 CAP ELCTLT 22UF 450 10 25V 54473 ECE A25V2 l A22CR7 152 0333 00 SEMICOND DVC DI SW SI 55V 200MA 0 35 07263 6012 A22CR8 152 0333 00 SEMICOND DVC DI SW ST 55V 200MA D0 35 07263 FDH 6012 A 2CR10 152 0333 00 SEMICOND DVC DI SW SI 55V 200MA 00 35 07263 6012 22 811 152 0333 00 SEMICOND DVC D1 SM SI 55V 200MA 00 35 07263 FDH 6012 A22CR15 152 0333 00 SEMICOND DVC DI SW SI 55V 200MA 0 35 07263 FDH 6012 A2 CR19 152 0141 02 SEMICOND DVC DI
237. AT As desired CONTROL ILLUM MEDIUM rear panel CALIBRATOR 0 4 V 12 Coaxial Cable 18 inch 13 Coaxial Cable 42 inch 15 Adapter BNC T D2 CHECK HORIZONTAL GAIN AND LOW FREQUENCY LINEARITY NOTE First perform step D1 then proceed D2 SETUP CONDITIONS 7904A Controls HORIZONTAL MODE 2 N a 3 a m 23 5 Test Equipment Controls Time Base Triggering Sweep Rate Auto AC External 5 us div Signal Standardizer Vert or Horiz Gain Rep Rate 100 kHz 4593 419 a Align the bright vertical trace on the center vertical graticule line using the signa standardizer Position control b CHECK that the second and tenth vertical traces align with the second and tenth graticule lines within 0 08 division CHECK along the horizontal graticule line for 0 05 division or less error at each vertical graticule line intersection d Move the signal standardizer to the HORIZ compartment and change the HORIZONTAL MODE switch to A e CHECK that the deflection between the second and tenth graticule lines is the same as in part c of this step within 0 08 division 5 23 Checks and Adjustment 7904A Part 1 Check D3 CHECK HIGH FREQUENCY TIMING D4 CHECK X Y DELAY COMPENSATION NOTE If the preceding step was not performed first perform step D1 then proceed SETUP C
238. C DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SIG SI 225V 0 24 00 7 516 51 225 0 2 00 7 516 51 225 0 2 00 7 516 51 225 0 2 00 7 SIG SI 225V 0 2A D0 7 SIG S1 225V 0 2A 00 7 SI6 51 225V 0 2A D0 7 SI6 51 225V 0 2A 00 7 16 51 225V 0 2A D0 7 516 1 025V 0 2A D0 7 SIG SI 225V 0 2A D0 7 RECT SI 10KV 10MA RECT SI 10KV LOMA A1XJ RECT S1 600V 0 5A RECT ST 600V 0 5A SEMICOND DVC DI SIG S1 225V 0 2A D0 7 SEMICOND 0 0 01 516 51 225 0 2 00 7 SEMICOND DVC DI S1G SI 225V 0 2A DO 7 SEMICOND DVC DI S1G SI 225V 0 2A DO 7 SEMICOND DVC DI RECT S1 400V 1A DO 41 LAMP GLOW 90V MAX 0 3MA AID T WIRE LD LAMP GLOW 90V MAX 0 3MA AID T WIRE LD LAMP GLOW 90V 0 3MA AID T WIRE LD LAMP GLOW 90V MAX 0 3MA AID T WIRE LD LAMP GLOW 90V MAX 0 3MA AID T WIRE LD Mfr Code 80009 80009 59660 59660 59660 05397 59660 59660 51406 51406 51406 51406 59660 51406 51406 51406 60705 51406 51406 50705 51406 51406 54473 54473 52763 51406 59860 59660 59660 59660 59660 59660 07263 07263 07263 07263 07263 07263 07263 07263 07263 07263 07263 07263 52306 52306 25403 25403 07263 07263 07263 07263 14433 0213 0213 0213 0213 TKoe13 Mfr Part No 670 5841 20 670 5841 21 871 533 103 871 533 103 871 533 103
239. CE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE INTENSITY Fully counterclockwise HORIZONTAL INTENSITY esses Fully counterclockwise oe B TRIGGER SOURCE VERT MODE rd dei FOGUS p MCI Midrange Vertical Deflection READOUT INTENSITY OFF in detent pir dee 4 GRAT Midrange EO BEAMFINDER Pushbutton out Input Coupling Gnd or Off 1 ms div 4593 518 Sweep Rate a Within the plug in extender disconnect the top connector on the left and right sides labeled A20 and B20 Connect each female connector to one of the test oscilloscope channels with the 42 inch 50 ohm coaxial cables and 50 ohm bnc terminations omit the 50 ohm bnc terminations if the test oscilloscope has a 50 ohm input impedance b Set the test oscilloscope for differential operation between the two channels added dispiay mode with one channel inverted Establish a ground reference level for the test oscilloscope by positioning the trace to the center horizontal line of the graticule Do not change the test oscilloscope Position controls after setting this ground reference 5 50 Set both channels of the test oscilloscope for dc input coupling EXAMINE the test oscilloscope display for a dc level within 1 division 50 millivolts of the ground reference level in the LEFT RIGHT and AD
240. CHOP DRIVE CRT DISPLAY BLANKED 13 i 4593 54 Figure 3 5 A Input and output pins for Chop Counter 04340 B idealized waveforms for Chop Counter stage The repetition rate of the output signals from this stage is determined by the setting of the HORIZONTAL MODE switch When the HORIZONTAL MODE switch is set to any position except CHOP the repetition rate of the Vertical Chopping Signal output at pin 1 is one megahertz one half clock rate This determines the switching between the LEFT and RIGHT VERT units when the VERTICAL MODE switch is set to CHOP At the same time the repetition rate of the Plug In Chop Command at pin 8 is 0 5 megahertz one fourth clock rate This provides a chopping signal that controis switching between channels in dual trace vertical units The relationship between these output signals and the clock input is shown by the waveforms in Figure 3 5B in the area between and During this time the Horizontal Chopped Blanking at pin 4 remains When the HORIZONTAL MODE switch is set to CHOP the basic repetition rate of the Vertical Chopping Signal and the Plug In Chop Command is altered For example if the HORIZONTAL MODE switch is changed to the CHOP position at time T see Fig 3 5B a HI level is 3 18 applied to pin 6 This stage continues to produce outputs at pins 1 and 8 in the normal manner until both outputs are at their HI level See time T this
241. CIMAL TO GENERATOR U2257B BCD CONVERTER 92203 02204 102244 02246 X OUTPUT ROW HORIZONTAL AMPLIFIER DECODER HARACTER CONVERTER POSITION U2257A 02185 42186 92202 92263 02264 1429 31 1767 117 Figure 3 21 Detailed block diagram of the Readout System SN 8031767 amp Above REV NOV 1985 3 43 Theory of Operation 7904A The signals at pin 12 13 and 14 are produced only when the triangle waveform is on its negative slope and the trape zoidal waveform has reached the lower level The timing sequence of these waveforms is important to the operation of the Readout System see expanded waveforms in Fig 3 12 The Z Axis inhibit command at pin 14 is produced first This negative going signal provides a blanking pulse to the Z Axis Logic stage to blank the CRT before the display is switched to the Readout System It also produces the strobe pulse through Q2138 and CR2139 which is con nected to pin 15 of U2232 The purpose of this configuration is to prevent the Zeros Logic and Memory stage U2232 from storing incorrect data during the quiescent period of the strobe pulse When the strobe pulse goes positive CR2139 is reverse biased to dis connect Q2138 and aliow U2232 to operate in the normal manner The next signal to be produced is the X Y inhibit Command at pin 13 This positive going signal disconnects the plug in signals from the vertical and h
242. D positions of the VERTICAL MODE switch ADJUST the A DC Center adiustment R255 on the A14 Trigger Selector Board for a dc level within 1 division 50 millivolts of the ground reference level in the LEFT RIGHT and ADD positions of the VERTICAL MODE switch Install the signal standardizer in the 7904A LEFT VERT compartment Set the VERTICAL MODE switch to LEFT Set the signal standardizer Test selector to Trigger Step Resp and the Rep Rate to 1kHz Use the signal standardizer Position and Amplitude controls to center a 6 division display on the test oscilloscope Set the test oscilloscope sweep rate to 0 5 millisecond division EXAMINE the test oscilloscope display for less than 3 and 396 aberrations ADJUST the A Thermal adjustment R270 on the A14 Trigger Selector Board for optimum square wave displayed on the test oscilloscope Checks and Adjustment 7904A Part and Performance Check Set the signal standardizer Test selector to Trigger Gain and the Rep Rate to 1 MHz Use the signal standardizer Position control to move the bright trace display on the test oscilloscope to the center graticule line EXAMINE the test oscilloscope display for nine traces with six divisions of vertical deflection between the center seven traces within 0 6 division 300 millivolts wHhin 30 millivolts ADJUST the A Gain adjustment R274 on the A14 Trigger Selector Board for a test oscillosco
243. E 50 5 A29R516 321 1068 01 RES FXD 50 5 OHM 0 5 0 1254 TC TO 57668 RBl14 50 5 A 9R522 315 0332 00 RES FXD FILM 3 3K OHM 525 0 25W 57668 NTR25J EO3K3 A29R523 315 0101 00 RES FXD FILM 100 5 0 25 57668 NTR25J E 100E A 9R524 315 0682 00 RES FXD FILM 6 8K OHM 5 0 25W 57668 NTR25J EO6KB A29R526 315 0511 00 RES FXD FILM 510 OHM 54 0 25W 19701 5043CX510R0J A29R528 321 1068 01 RES FILM 50 5 OHM 0 5 0 125W TC T0 57668 RB14 DXE 50 5 A29R602 321 1068 01 RES FILM 50 5 OHM 0 54 0 1254 TC TO 57668 RB14 DXE 50 5 A29R603 321 0074 00 RES FILM 57 6 OHM 125 0 1254 TC TO 91637 CMF55115G57R60F A 9R604 321 0074 00 RES FILM 57 6 OHM 125 0 1254 TC TO 91637 CMF55116G57R60F 298606 321 0187 00 RES FXD FILM 866 OHM 125 0 125W TC TO 07716 CEAD866ROF 298620 321 0074 00 RES FILM 57 6 OHM 125 0 1254 TC TO 91637 CMF55116G57R60F A29R622 321 0074 00 RES FXD FILM 57 6 OHM 12 0 1254 TC TO 91637 CMF55116G57R60F A29R624 321 0218 00 RES FILM 1 82K OHM 12 0 125W TC TO 19701 5033ED1K82F A 29R626 321 0187 00 RES FXD FILM 866 OHM 1 0 125W TC TO 07716 CEADB66ROF A290518 155 0022 00 MICROCKT DGTL CHANNEL SWITCH 80009 155 0022 00 7 68 REV JUL 1987 Replaceable Electrical Parts 7904 Tektronix _ Serial Assembly No Mfr ent No Part No Effective Dscont Name amp Description Code Mfr Part No A30 570 0702 06 CIRCUIT BD A
244. E IN 46711 12954 CORP 8700 E THOMAS RD SCOTTSDALE AZ 85252 P 0 BOX 1390 12969 UNITRODE CORP 580 PLEASANT ST WATERTOWN MA 02172 14193 CAL R INC 1601 OLYMPIC BLVD SANTA MONICA CA 90404 14433 ITT SEMICONDUCTORS DIV WEST PALM BEACH FL 14550 MICRO SEMICONDUCTOR CORP 2830 S FAIRVIEW ST SANTA ANA 92704 14731 HARRIS CORP WEB PRESS DIV P 0 BOX 515 WESTERLY RI 02891 14752 ELECTRO CUBE INC 1710 S DEL MAR AVE SAN GABRIEL 91776 14936 GENERAL INSTRUMENT CORP 600 W JOHN ST HICKSVILLE NY 11802 DISCRETE SEMI CONDUCTOR DIV 15238 SEMICONDUCTORS 500 BROADWAY LAWRENCE 01841 DIVISION OF INTERNATIONAL P 0 BOX 168 TELEPHONE AND TELEGRAPH CORP 15454 INC 2905 BLUE STAR ST ANAHETM CA 92806 RODAN DIV 18324 SIGNETICS CORP 811 ARQUES SUNNYVALE 94086 19396 ILLINOIS TOOL WORKS INC 900 FOLLIN LANE S E VIENNA VA 22180 PAKTRON DIVISION 19701 MEPCO ELECTRA INC P 0 BOX 760 MINERAL WELLS TX 76067 A NORTH AMERICAN PHILIPS CO 21847 MICROWAVE INC 825 STEWART DR SUNNYVALE CA 94086 SUB OF TRW INC 22526 DU PONT E I DE NEMOURS AND CO INC 30 HUNTER LANE CAMP HILL PA 17011 DU PONT CONNECTOR SYSTEMS 24546 CORNING GLASS WORKS 550 HiGH ST BRADFORD PA 16701 25088 SIEMENS CORP 186 WOOD AVE 5 ISELIN NJ 08830 25403 ELECTRONIC CORP PROVIDENCE PIKE SLATERSVILLE RI 02876 SEMICONDUCTOR AND MICROCIRCUITS DIV 27014 NATIONAL SEMICONDUCTOR CORP 2900 SEMICONDUCTOR DR SANTA CLARA CA 95051 31433 UNION CARBIDE CORP PO BOX 5
245. ED position Single shot operation Selected by front panel switches GATE Triggered by the trailing edge of the GATE selected by the front panel switch EXT Controlled through rear panel remote control connector DISPLAY internal Hluminated with variable edge lighting Eight divisions vertical by ten divisions horizontal Each division equals one cent meter Eight divisions vertical by ten divisions horizontal Each division equals 0 5 centimeter P31 P11 Limits display within graticule area when actuated Within 0 1 division checked over entire 8 x 10 division graticule area 1 7 General information 7904A TABLE 1 3 CONT Electrical Characteristics TEST CONDITIONS TEKTRONIX C 51 camera with lens set at f 1 2 1 0 5 Object to Image Ratio Polaroid 20 000 ASA fiim CRT Characteristics Minimum Photographic Writing Speed with out film fogging Standard crt _ Phosphor _ Writing Speed Option 4 Approx 2 cm ns Option 13 Option 78 4 cm ns 2 5 cm ns With intensity and Graticule Illumination controls fully counterclockwise open the camera shutter for 5 minutes Resulting print must be completely black Exposure Defects REMOTE CONNECTORS AND SWITCHES High medium and off Three position switch located on rear panel of power supply S BAUR RR LEE EE E ARR sin CONTROL ILLUMINATION CAMERA POWER
246. ENTS The following procedures describe methods of checking individual components in the 7904A Components which are soldered in place are best checked by first disconnecting one end This isolates the measurement from the effects of surrounding circuitry WARNING To avoid electric shock hazard always disconnect the 7904A from the power source before removing or replacing components Fuses Access to the 7904A line fuse is through the instrument rear panel To check for an open fuse measure continuity with an ohmmeter Transistors A good check of transistor operation is actual performance under operating conditions A transistor can most effectively be checked by substituting a new component for it or one which has been previously checked However be sure that circuit conditions are not such that a replacement transistor might also be damaged If substitute transistors are not available use a dynamic tester Static type testers are not recommended since they do not check operation under simulated operating conditions 4 8 integrated Circuits Integrated circuits can be checked with a voltmeter test oscilloscope or by direct substitution A good understanding of the circuit operation is essential to troubleshooting circuits using integrated circuits addition operating waveforms logic levels and other operating information for the integrated ciruits are given in Section 3 Theory of Operation and Section 8 Di
247. ES FILM 20K OHM 5 0 258 57668 252 20K Al6R614 321 0385 00 RES FILM 1G0K OHM 125 0 1258 TC T0 19701 5033ED100KOF 168615 311 1235 00 RES VAR 100K OHM 0 5W 32997 3386 04 104 A16R616 321 0309 00 RES FILM 18 2K OHM 125 0 1254 TC TO 19701 5033ED16K20F 168619 321 0385 00 RES FXD FILM 1G0K OHM 1 0 125W TC TO 19701 5033ED1L00KOF 168620 311 1232 00 RES VAR NONWW TRMR 50K OHM 0 SW 32997 3386 04 503 168621 321 0281 00 RES FXD F1LM 8 25K OHM 12 0 125W TC T0 19 01 5043ED8K250F 168624 321 0357 00 RES FILM 51 10 OHM 125 0 1254 TC TO 07716 CEAD51101F A16R625 311 1230 00 RES VAR 20K OHM 0 SW 32997 3386F T04 203 168626 321 0314 00 RES FILM 18 2K OMM 12 0 1250 TC T0 19701 5043 018 20 168629 321 0326 00 RES FILM 24 3K 0 1 0 125 0 19701 5043ED 4K30F A16R630 311 1230 00 RES VAR NONWW 20K OHM 0 OY 32997 33868F T04 203 168631 321 0450 00 RES FXD FILM 475K OHM 15 0 1254 TC 10 19701 5043ED475K0F 168632 321 0450 00 RES 475 OHM 14 0 1254 TC TO 19701 5043ED475KO0F Ai6R638 321 0326 00 RES F1LM 24 3K OMM 12 0 1254 TC TO 19701 5043ED24K30F A16R642 323 0168 00 RES FXD FILM 549 OHM 125 0 5M TC TO 19701 5053RD549RO0F 168543 321 0065 00 RES FXD FILM 46 4 OHM 125 0 1254 TC TO 57668 RBIAFXE 46 4 16 546 321 0080 00 RES F
248. Figure 3 6 The discrete components that make up each logic function are identified TRACE SEPARATION The Trace Separation stage is made up of discrete components Q4438 Q4442 Q4448 and Q4456 This stage produces the Trace Separation output to the AUX Y Axis Input of the Vertical Amplifier circuit and offsets the B sweep display when operated in a dual sweep mode horizontal The level of this output current is determined by the setting of the VERT TRACE SEPARATION B control The current from the VERT TRACE SEPARATION B control is switched so that the Trace Separation output is provided only when the B sweep is being displayed in the ALT or CHOP horizontal modes and not when the B sweep only is being displayed nor during independent pairs operation sweep siaving 3 19 Theory of Operation 7904A RIGHT MODE FROM VERTICAL MODE SWITCH CHOP MODE MODE VERTICAL CHOPPING SIGNAL FROM PIN 1 U4340 CR4369 VERTICAL ALTERNATE COMMAND FROM PIN 6 U4368 UISPLAY RIGHT COMMAND CR4368 7 Figure 3 6 Logic diagram of Vertical Mode Logic stage The VERT TRACE SEPARATION B control provides current to the Trace Separation output through R4456 and Q4456 when Q4456 is forward biased When the B sweep is being displayed for ALT or CHOP horizontal operation the Display B Command at the base of Q4442 is This forward biases Q4442 causing its collector to go negative to forward bias Q4448 Then
249. Figure 4 14 shows the cross sectional differences which must be observed when working with an instrument that contains both types of Hypcon connectors PONES Damage to the elastomer contact holder can result if the connectors are not mated properly with the board receptacle When replacing the hybrid insert it into the board opening and then position the Hypcon connector in the board registration holes for perfect alignment The outer portion of the hypcon frame should be flush with the circuit board before the four mounting screws are tightened Avoid touching the hybrid and elastomer contact holder with your fingers finger oils can degrade reliability A procedure for removal and replacement is included in Figure 4 14 Hybrid substrate contact numbers 1 and 20 are printed on the substrate at the index corner See Figure 4 2 Semiconductor lead configurations INTERCONNECTING PINS Two methods of interconnection used in this instrument to electrically connect the circuit boards with other boards and components When the interconnection is made with a coaxial cable a special end iead connector plugs into a socket on the board Other interconnections are made with a pin soldered into the board Two types of mating connectors are used for these interconnecting pins If the mating connector is mounted on a plug on circuit board a special socket is soldered into the board If the mating connector is on the end of a lead
250. Gate level at pin 14 LO Display Command at pin 15 Gate level at pin 4 and Delay Mode Control Out level at pin 5 The B INTENSITY control determines the output current when the B Gate level at pin 4 and the Display B Command at pin 15 are both The current from the B INTENSITY control is connected to the Z Axis Logic stage through R4483 The current level established by the intensity controls can be altered by the Auxiliary Z Axis current level at pin 9 The current at this pin can come from the Z AXIS INPUT connector on the rear panel see Diagram 3 or from any of the plug in compartments This current either increases or decreases depending on polarity the output current to modulate the intensity of the display Input from the Z AXIS INPUT connector allows the trace to be modulated by external signals The Auxiliary Z Axis inputs from the plug in compartments allow special purpose plug in units to modulate the display intensity Diodes CR4473 and CR4474 limit the maximum voltage change at pin 9 to about and 0 6 volt to protect the Z Axis Logic stage if an excessive voltage is applied to the Z AXIS INPUT connector Table 3 6 shows Input Output combinations of the Z Axis Logic stage HORIZONTAL BINARY The Horizontal Binary stage develops the Display B Command to indicate which horizontal plug in unit is providing the displayed sweep When the level is HI the B horizontal unit is displayed when it is LO the
251. HBUTTON SWITCHES The pushbutton switches used on the 7904A Oscilloscope mainframe are circuit board mounted First remove the associated circuit board following the procedure given under Circuit Boards in this section Figure 4 17 gives removal and replacement instructions for the pushbutton switch assemblies mounted on the A5 Mode Switch Board Pushbutton switches mounted on the A1 Front Panel and the A2 Display Control boards are soldered onto the circuit boards Use the soldering methods given under Soldering Techniques in this section to replace these switches GRATICULE LIGHT BULBS To remove or replace the graticule light bulbs first remove the plastic crt mask light filter and metal light shield Pull on the white tabs to remove the graticule lamp assembly Unsolder the base of the damaged bulb assembly from the A30 Graticule Lights board and pull the bulb out of the circuit board Reverse the order of removal for replacement POWER TRANSFORMER Replace the power transformer only with a direct replacement Tektronix transformer Remove and replace ihe power transformer as follows 1 Remove the Ai2 Controi Rectifier board as described under Circuit Boards in this section 2 Unsoider the remaining transformer leads from the A12 Control Rectifier board Remove the excess solder from the circuit board pads see Soldering Techniques Note the position of the transformer leads so they may be correctly replaced 3 Remove
252. HM 57 0 25W RES FXD FILM 330 OHM 5 0 25W RES F1LM 470 OHM 5 0 250 RES FXD FILM 180 OHM 5 0 25W RES FILM 5 1K OHM 5 0 25M RES FXD WW 1 5 OHM 5 3W RES FXD FILM 4 3K OHM 5 0 25W RES FXD CMPSN 1K OHM 10 1W RES FXD FILM 120 OHM 54 0 25W RES FXD FILM 12K OHM 5 0 25W RES FILM 1 8K OHM 52 0 SW RES FILM 20K 55 0 25W RES FILM LOK 5 0 25 4 RES FXD FILM 40K QHM 0 17 0 1254 TC T9 RES FILM 40K OHM 0 19 0 125W TC T9 RES FXD FILM 150 0HM 54 0 25W RES FXD FILM 100K OHM 525 0 25W RES FILM 820 54 0 25W RES FXD 510 5 0 25 RES FILM 470 5 0 25 RES 180 OHM 5 0 25W RES FILM 5 1K OHM 55 0 25W RES FXD WW 2 2 OHM 5 2W RES FILM 28 0K OHM 0 1 0 125W TC T9 RES 12 0K OHM 0 1 0 125W TC T9 RES FXD FILM 1 5K OHM 5 0 25W RES FXD FILM 12K OHM 5 0 25W RES FXD FILM OHM 54 0 254 RES FILM 8 2K OHM 5 0 25M RES FILM 200 5 0 25 RES FILM 39K 5 0 25 RES FXD WW 0 025 OHM 57 0 5M RES FXD FILM 150 OHM 55 0 25W RES FXD FILM 4 3K OHM 525 0 25W RES FXD FILM 40K OHM O 175 0 125W 9 RES FXD FILM 12 0K 0 125 0 125W TC T9 RES FXD FILM 9 1K OHM 5 5 0 25W RES FILM 1K OHM 555 0
253. HORIZONTAL 344 4 X COMPENSATION INHIBIT A HORIZONTAL gt i 5 DELAY MODE CONTROL gt 412 MAINFRAME CHANNEL SWITCH SIGNAL 16 DISPLAY B X COMPENSATION INHIBIT B HORIZONTAL X COMPENSATION INHIBIT A HORIZONTAL A HOLDOFF B MODE B HOLDOFF DELAY MODE CONTROL determine the correct instrument operation in relation to the plug in units instailed or selected plug in control settings and 7904A control settings HORIZONTAL LOGIC The Horizontal Logic stage performs three separate logic functions A Sweep Lockout B Sweep Lockout and Alternate Pulse Generation The majority of the logic for these functions is contained within the horizontal Logic U4428 Figure 3 2 identifies the three individual stages of U4428 and the input and output terminals associated with each Note that some of the input signals are connected internally to more than one of the individual stages Sweep Lockout The A Sweep Lockout portion of the Horizontal Logic IC 04228 produces an output ievel at the collector of Q4462 A Sweep Inhibit that determines when the A HORIZ time base unit can produce a sweep If this output is HI the A HORIZ unit is locked out disabled not producing a sweep If the level is LO the A HORIZ unit is enabled and produces a sweep when triggered 3 8 A SWEEP LOCKOUT P XX B SWEEP LOCKOUT STAGE A LOCKOUT STAGE 15 B LOCKOUT 04428 ALTERNATE PULSE STAGE
254. HT VERT CHECK sequentially select ail positions of the VERTICAL MODE switch and check for a stable display of only the 10 kHz waveform Set the VERTICAL MODE switch to ALT the HORIZONTAL MODE switch to ALT and the and B TRIGGER SOURCE switches to VERT MODE CHECK that the B HORIZ time base is triggered on the 1 kHz waveform and the HORIZ time base is triggered on the 10 kHz waveform set the time base Triggering Level controls for triggered sweeps Checks and Adjustment 7904A Part I Performance Check D HORIZONTAL SYSTEM Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 11 Time Mark Generator 2 3 Amplifier two required 4 6 Low Frequency Sine Wave Generator 10 Signal Standardizer D1 HORIZONTAL SYSTEM PRELIMINARY SETUP a Perform the Performance Check Power Up Sequence b Refer to Section 6 instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure c Set the 7904A controls as follows POWER 5 On VERTICAL MODE RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE A INTENSITY CE ER D Midrange HORIZONTAL MODE B INTENSIFY ord Midrange B TRIGGER SOURCE cca ts VERT MODE READOUT INTENSITY OFF in detent GR
255. Horizontal compartment 04492 is saturated The emitter of Q4488 is held at a HI level so even when the display B Command is 04488 does not conduct The Z Axis logic IC selects the B Intensity input when the signal at the collector of Q4492 is regardless of other control inputs Transistors Q4494 and Q4498 drive the A and B INTENSITY indicator lights With an amplifier unit installed in either A or B Horizontal compartments diode CR4496 CR4493 conducts This prevents Q4494 and Q4498 from turning on when the HORIZONTAL MODE switch is set to ALT or CHOP With an amplifier unit installed in the A Horizontal compartment the signal at the collector of Q4492 is HI This turns Q4494 and the B INTENSITY indicator lamp which indicates that the Z Axis is controlled by the time base unit installed in the B Horizontal compartment The signal at the collector of 04492 is LO when an amplifier is installed in the B Horizontal compartment Now Q4498 is saturated Base current flows from the 5 V lamp supply through the B indicator lamp and the resistor 84493 to the base of 04498 This base current is not sufficient to light the B INTENSITY indicator lamp so the INTENSITY indicator lamp is turned on This indicates that the Z Axis is controlled by the time base unit in the A Horizontal compartment 3 21 Theory of Operation 7904A When time base units are installed in both A and B Horizontal compartments Q4494 and 044
256. I CAP DI CAP DI FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER 01 Di DI FXD CER DI FXD CER DI CAP FXD CER DI CAP CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER 01 DI 0 010 100 0 500 70 Q1UF 100 0 500V 20 Q1UF 100 0 500V 0 1UF 2075 50V 0 001UF 20 500V 0 O1UF 100 0X 500V 0 001UF 20 4000V 0 001UF 20 4000V 0 0010 20 4000 0 001UF 20 30007 0 O3UF 80 20 200V 0 001UF 2076 4000V 0 001UF 2076 4000V 0 001UF 20 4000V 0 O1UF 480 207 2000V 0 0068UF 30 4000V 0 0068UF 30 4000V 0 01UF 480 207 2000V 0 0068UF 30 4000V 0 0068UF 307 4000V CAP FXD ELCTLT 4 7UF 75 10 160V0C CAP FXD ELCTLT CAP FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP FXD CER DI CAP CER DI CAP FXD CER DI CAP FXD CER DI DI 4 JUF 475 1025 160VDC 3 9PF 0 25PF 500V 0 001UF 20 4000V 0 001UF 100 07 500V 0 0010 100 0 500V 0 01UF 100 07 500V 0 100 0 500 0 01UF 4100 07 500V 0 01UF 100 0 500V SEMICOND DVC D1 S1G SI 225V 0 2A D0 7 SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DYC DI SEMICONO DVC DI SEMICOND DVC D1 SEMICOND DV
257. I HIGH VOLTAGE DIVIDER RES VAR NONWW PNL 5M OHM 20 0 5W RES CMPSN 3M OHM 5 0 5W RES FXD CMPSN 2 2M 5 0 5W RES FXD CMPSN 10K OHM 55 0 25W RES VAR 20K OHM 0 5M RES FILM 12K OHM 55 0 25W RES FXD CMPSN 18K OHM 5 0 25M RES FXD CMPSN 22 M OHM 54 0 258 RES FXD CMPSN 100 OHM 55 0 25W RES FXD CMPSN 100K OHM 5 0 25W RES FXD CMPSN 4 7K OHM 55 0 250 RES CMPSN 4 7K 525 0 25M RES CMPSN 4 7K OHM 54 0 254 RES CMPSN 330 OHM 5 0 25W RES FXD CMPSN 100 5 0 25 RES FXD WW 1 5 OHM 10A 1W RES CMPSN 100 OHM 54 0 25W RES FXD CMPSN 10 5 0 05 RES FXD CMPSN 100 OHM 5 0 SW RES FXD CMPSN 13M OHM 525 0 25W RES FXD CMPSN 20K OHM 5 6 0 25W RES VAR TRMR 25K OHM 0 SW RES FXD FILM 294K OHM 18 0 1254 TC TO RES FXD CMPSN 1K OHM 52 0 54 RES FXO FILM 470K OHM 525 0 258 RES FXD CMPSN 330 OHM 5 0 25W RES FXD 680 OHM 51 0 25W RES FXD FILM 3 3K OHM 5 5 0 25W RES FXD CMPSN 62K OHM 5 6 0 5W RES FILM 15 OHM 55 0 25W RES VAR NONWW 100K OHM 0 SW RES FXD FILM 6 49K OHM 125 0 1259 0 Mfr Code 0213 0213 22526 22526 22526 22526 22526 04713 00213 01121 01121 01121 01121 01121 01121 01121 01121 01121 01121 01121 80009 80009 01121 01121 0112
258. ILLER J W DIV AMF INC POTTER AND BRUMFIELD DIV C W INDUSTRIES TEKTRONIX INC MEPCO ELECTRA INC SWITCHCRAFT INC SUB OF RAYTHEON CO TRW INC TRW ELECTRONICS COMPONENTS DIV TRW CAPACITORS DALE ELECTRONICS INC GTE PRODUCTS CORP LIGHTING PRODUCTS GROUP HILLSBORO MINIATURE LAMP PLANT TOPTRON CORP COMPONENT CONCEPTS INC ZMAN AND ASSOCIATES TOKYO COSMOS ELECTRIC CO LTD MULTI COMP INC ZMAN amp ASSOCIATES REV JUL 1987 1200 COLUMBIA AVE 8061 AVONIA RD 3601 W HOWARD ST 640 PAGE MILL RD 526 INDUSTRIAL WAY WEST 1148 FRANKLIN RD SE 2820 COLLEGE AVE 580 PLEASANT ST 6135 AIRWAYS BLVD PO BOX 21947 134 FULTON AVE ONE PANASONIC WAY 12920 NE 125TH WAY 5334 STERLING CENTER DRIVE 240 PLATO BLVD 927 E STATE PKY 87 MARSHALL ST 16931 MILLIKEN AVE 60 BOSTON ST 2155 N FORBES BLVD 7158 MERCHANT AVE 8711 WEST ROOSEVELT 1327 6TH AVE 114 OLD STATE RD PO BOX 14460 645 W 11TH ST 2500 HARBOR BLVD 298 10TH AVE 5 W 401 N BROAD ST 19070 REYES AVE P 0 BOX 5825 200 RICHLAND CREEK DR 550 DAVISVILLE RD P 0 BOX 96 4900 5 W GRIFFITH DR P BOX 500 22 COLUMBIA RD 5555 N ELSTRON AVE 301 WEST 0 ST P 0 BOX 609 WEST MAIN ST TOKYO 3229 PINE ST 7633 5 180TH 2 268 SOBUDAI ZAWA 3005 SW 154TH TERRACE 3 7633 SO 180TH RIVERSIDE CA 92507 FAIRVIEW PA 16415 SKOKIE IL 60076 PALO ALTO CA 94304 EATONTOWN NJ 07724 MARTETTA GA 30067 STATE COLLEGE PA 16801 WATERTOWN MA 02172 CHATTANOOGA T
259. ILM 7 15K OHM 125 0 125W TC T0 RES FXD F1LM 7 32K 125 0 1250 TC T0 RES FXD FILM 1 33K OHM 125 0 125W TC TO RES FILM 1K OHM 55 0 254 RES FXD F1LM 27 5X 0 25W RES FXD F1LM 47 5 0 53 0 125W TC TO RES FXD CMPSN 4 7 5 0 25 RES FXD CMPSN 3 3K OHM 5 1W RES FXO FILM 270 OHM 5 0 25W RES FXD FILM 10 OHM 54 0 254 RES FILM 24 9K OHM 125 0 5W TC T0 RES FXD FILM 56K OHM 5 0 5W RES FXD FILM 200 OHM 5 5 0 25W RES FXD FILM 15 OHM 54 0 25W RES FXD FILM 1 82K OHM 125 0 1254 TC TO RES FILM 1 33K OHM 13 0 1254 TC TO RES FXO FILM 24 9K OHM 125 0 50 TC TO RES FXD CMPSN 27K OHM 5 1W RES FXD FILM 200 OHM 575 0 25W RES FXD FILM 10 OHM 54 0 25W RES FXD FILM 27 OHM 5 0 25W RES FXD CMPSN 2 7 OHM 5 1W RES FILM 33K OHM 5 0 5W RES FXD CMPSN 2 2K OHM 5 1W RES THERMAL 50 HM 10 NTC TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL SEMICOND DVC DI ZEN SI 10V 54 0 4W D0 7 SEMICOND DVC DI ZEN 51 300 5 0 48 00 7 Mfr Code Mir Part No 5 668 19701 57668 18701 19701 57658 19701 01121 07716 32997 07716 44655 44655 91637 57668 19701 07716 19701
260. ILM 66 5 1 0 1254 70 70 91637 55115086 50 A16R647 321 0084 00 RES FILM 73 2 OHM 13 0 1254 TC TO 91637 CMF55116G73R20F A16R648 323 0168 00 RES FILM 549 OHM 12 0 5W TC TO 19701 5053RD549RO0F A16R649 321 0010 00 RES FXD FILM 12 4 1 0 1254 0 57668 RBi4FXE 12 4 Ai6R650 323 0136 00 RES FXD 255 OHM 12 0 54 TC TO 24546 6500550 A16R651 315 0471 00 RES FXD F1LM 470 5 0 25 57668 NTR25J E470E A16R652 315 0153 00 RES FILM 15K OHM 5 0 25 19701 5043 15 00 A16R653 315 0472 00 RES FILM 4 7K OHM 525 0 250 57668 NTR25J EO4K7 A16R654 315 0512 00 RES FILM 5 1K OHM 555 0 25W 57668 NTR25J FO5K1 16 655 315 0102 00 RES FILM 1K OHM 545 0 258 57668 25 01 0 168656 321 0126 00 RES FXD FILM 200 OHM 175 0 125 TC TO 19701 5033 D 200R0F 168657 321 0237 00 RES FXD FILM 2 87K OHM 126 0 125W TC TO 07716 CEAD 28700F Ai6R658 321 0126 00 RES FXD FILM 200 OHM 1 0 125W TC TO 19701 5033 020080 7 42 REV JUL 1987 ent No A15R659 A16R671 AL6R672 Al6R6 5 A16R680 15868 16 682 A16R683 AlOR684 168690 16 691 A16R694 16 500 16 508 16 538 16 552 16 555 16 582 16 583 16 584 16 600 16 608 16 648 16 657 16 682 16 684 16 694 160508 160538 160608 160638 160668 A16U682 160694
261. INE ADJUST INTERACTION as the first word of the instruction These terms are defined as follows 1 CHECK indicates the instruction accomplishes an electrical specification check Each electrical specification checked is listed in Table 5 2 Performance Check Summary see Performance Check Summary discussion for more information EXAMINE usually precedes an ADJUST instruction indicates that the instruction determines whether adjustment is necessary If no ADJUST instruction appears in the same step the EXAMINE instruction concerns measurement limits that do not have a related adjustment Measurement limits following the word EXAMINE are not to be interpreted as electrical specifications They are provided as indicators of a properly functioning instrument and to aid in the adjustment process ADJUST describes which adjustment to make and the desired result We recommend that the adjustments not be made if a previous CHECK or EXAMINE instruction indicates that no adjustment is necessary INTERACTION indicates that the adjustment described in the preceding instruction interacts with other circuits The nature of the interaction is described and reference is made to the step s affected PERFORMANCE CHECK SUMMARY Table 5 2 Performance Check Summary lists the electri cal specifications that are checked in Part and Part of this section Table 5 2 is intended to provide a convenient means for l
262. L 22526 48283 036 QUANTITY OF 8 1 1910 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22506 48283 036 QUANTITY OF 4 1 1917 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 QUANTITY OF 5 101908 151 0508 00 TRANSISTOR UJT SI TO 98 03508 131520 101910 151 0341 00 TRANSISTOR NPN SI TO 106 04713 5 56919 A101916 151 0192 00 TRANSISTOR SELECTED 04713 5 58801 101928 151 0271 00 TRANSISTOR PNP 51 TO 92 04713 5 58236 8101934 151 0223 00 TRANSISTOR NPN SI TO0 92 04713 5 58026 101938 151 0223 00 TRANSISTOR NPN 51 10 982 04713 5 58026 101942 151 0301 00 TRANSISTOR PNP SI 0 18 04713 51898 A1Q1943 151 0198 00 TRANSISTOR SELECTED 04713 SPS8802 1 A101946 151 0198 00 TRANSISTOR SELECTED 04713 5 58802 1 101956 151 0302 00 TRANSISTOR 51 0 18 04713 51899 7 6 REV JUL 1987 Tektronix No Part No ALR301 303 0301 00 1 1900 311 1587 00 181901 315 0106 00 181902 311 1319 00 1 1903 315 0101 00 181905 315 0103 00 AiR1906 315 0103 00 AiRI908 315 0512 00 181909 315 0244 00 AiR1910 315 0104 00 1 1911 321 0143 00 181914 315 0471 00 161914 315 0201 00 1 1915 315 0104 00 A1R1916 315 0512 00 A1R1917 315 0153 00 A1R1918 315 0106 00 A1R1919 315 0105 00 1 1920 315 0101 00 1 1921 315 0105 00 1 1922 315 0202 00 181923 311 1339 00 ALRI924 311 1588 00 1 1925 315 0202 00 181926 315 0101 00 181927 321 0226 00 181928 321 0180 00 1 1929 321
263. L MODE switch to ALT Set the HORIZONTAL MODE switch to ALT or CHOP Notice that this is the same display obtained in step 29 slaved alternate operation READOUT 35 36 37 Turn the READOUT control clockwise until an alphanumeric display is visible within the top or bottom division of the crt graticule Change the deflection factor of the amplifier unit that is selected for display The readout display should change as the deflection factor 15 changed Likewise change the sweep rate of the time base unit which is selected for display the readout should change as the sweep rate is changed Set the time base unit for X10 magnification Notice that the readout display will change to indicate the correct magnified sweep rate If a readout coded 10X probe is available for use with the amplifier unit install it on the input connector of the right amplifier plug in unit Notice that the deflection factor indicated by the readout is increased by 10 times when probe is added Return the time base unit to normal sweep operation and disconnect the probe Sequentially select all of the VEHTICAL MODE and HORIZONTAL MODE switch positions Notice that the readout from a particular plug in occupies a specific location on the display area If either of the vertical plug in units is a dual trace unit the readout for channel 2 is displayed within the lower division of the crt graticule Return the VERTICAL MODE switch to LEFT and the HORIZ
264. LCTLT 1UF 20 35V CAP FXD MTLZD 1 QUF 10 50V FXD MICA DI 0 001UF 1 100V CAP FXD CER 01 100 5 200 CAP FXD CER D1 270PF 575 1000V D1 100PF 52 200V CAP FXD CER D1 270PF 55 1000V FXD CER 01 0 022 80 20 25V CAP FXD ELCTLT 0 27UF 20 50V ELCTLT 1UF 50 10 50V NPLZD CAP PLASTIC 1UF 20 200V CAP FXD PLASTIC 0 O1UF 10 200V CAP FXD PLASTIC O 22UF 10 200V ELCTLT 2 2UF 50 10 200V CAP FXD ELCTLT 2 2UF 50 10 200V CAP FXD ELCTLT LOUF 50 105 LOOVDC CAP FXD ELCTLT 10UF 50 1075 LOOVDC CAP ELCTLT 10UF 50 1075 100VDC CAP FXD ELCTLT 10UF 50 107 100VDC CAP FXO ELCTLT 330UF 50 10 25VDC CAP FXD ELCTLT 100UF 50 10 25VDC CAP FXD ELCTLT 330UF 50 10 25VDC CAP FXD ELCTLT LOOUF 50 10 25VDC ELCTLT 220UF 50 10 LOVDC CAP FXD ELCTLT 220UF 50 10 10 0 CAP ELCTLT LOQQUF 50 10 LOVDC CAP FXD ELCTLT 220UF 50 10 10VDC CAP FXD ELCTLT 47UF 50 10 16V CER DI 1UF 480 204 25V CAP FXD MTLZD 1 QUF 10 50V CAP FXD CER 01 0 1UF 20 50V CAP FXD MTLZD O 1UF 10 63V SEMICOND DVC D1 SW S1 55V 200MA D0 35 SEMICOND DVC DI SW ST 55V 200MA 0 35 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 SEMICOND DVC DI SW SI 30V 150MA 30V 00 35 SEMICOND DVC DI SW
265. LE READOUT SINGLE SHOT input connector The GATE switch selects whether A time base gate or B time base gate triggers the readout One frame of readout information is also displayed each time the READOUT MAN manual bution is pressed LEFT VERT RIGHT VERT HORIZ B HORIZ CHANNEL 1 CHANNEL 1 CHANNEL 1 CHANNEL 1 LEFT VERT RIGHT VERT A HORIZ B HORIZ CHANNEL2 CHANNEL 2 CHANNEL2 CHANNEL 2 C1675 8 Figure 2 4 Location of readout on the crt identifying the originating plug in and channel The brightness of the readout display when operating in the PULSED mode is set by the READOUT PRESET adjustment CARE OF CRT SCREEN The following precautions will proiong the useful of the crt screen used in this instrument 1 Use minimum beam intensity to produce a clear well defined display 2 Avoid repeated use of the same area of the screen If a particular waveform is to be displayed for a long period of time change the vertical position occasionally to use other portions of the display area 3 Use minimum READOUT INTENSITY VERTICAL AND HORIZONTAL MODE COMBINATIONS There are 20 possible combinations of VERTICAL MODE and HORIZONTAL MODE switch settings The possible number of display combinations is further multiplied as follows 1 The variety of plug in units avallable for use with this instrument 2 The interchangeability of plug in units ie either an amplifier or a
266. M 15 0 125W TC T0 RES FXO FILM 1 33K OHM 125 0 1254 TC TO RES FTLM 4 99K OHM 125 0 1250 TC T0 RES FILM 10K 54 0 25W Mfr Code 01121 01121 01121 32997 57668 19701 19701 57668 19701 57668 07716 57668 57668 57668 57668 19701 01121 19701 57668 19701 57668 02111 01121 57668 57668 01121 07716 19701 19701 19701 19701 57668 57568 57668 57668 57668 57668 19701 19701 19701 91637 19701 19701 91537 19701 19701 19701 19701 57668 57668 19701 57668 19701 19701 19701 19701 19701 19701 Mfr Part No 683015 10 435 81065 3006P W84 103 NTR25J E 100 5043CX10K003 5043CX10K00J 252 05 1 5043 240 02 NTR25J E100K CEAD301ROF NTR25J E470E NTR2SJ E200E NTR25J E100K NTR25J EOSK1 S043CX15K00J CB1065 5043CX1M000J NTR25J E 100E 5043 1 000 NTR25J E 2K 43P5021672 204718 NTR25J E 2K NTR25J E 100E RNK2211F CEAD732ROF 5043 0931 5043CX430R0J 5043 51 000 SO53RDSOSROF NTR25J E 100E NTR25J E300E NTR25J E47K0 NTR25J E 100 NTR25J E12K0 NTR25J E330E 9043CX51R00J 5043CX51R00J 5043 200 0 551180100 5033ED5K230F 5053 1 000 CMF551166100R0F 5043ED931ROF 5043CX22K00J92U 5043 1 0 5033 10 NTR25J E100K NTR25J E100K 5043CX10K00J NTR25J E24K0 5043CX820R0J SO33ED4K990F 5043 08 660 5033 01 330 5033 4 990 5043 10 002
267. M 3 40K 12 0 1254 TC TO 19701 5043ED3K400F 15 182285 321 0245 00 021190 8029999 RES FTLM 3 57K 1 0 125 70 19701 5043ED3K570F A15A1R2285 321 0247 00 021190 8029999 RES FILM 3 65K OHM 1 0 125W TC T0 19701 5043ED3K650F AL5AIR2285 321 0248 00 8021190 029999 RES FILM 3 74K OHM 12 0 125W TC 10 19701 5043 03 740 R2285 IS SELECTABLE 15 152286 321 0210 00 8010100 029999 RES FILM 1 OMM 1 0 125W TC T0 19701 5033 AL5A1R2286 307 0651 00 8030000 RES 5 3 3 GHM 5 0 150W 11238 750 51 R3 3K CHM 15 182287 321 0199 00 8010100 8029999 RES FXD FILM 1 15K OHM 12 0 125W TC TO 07716 11500 15 182288 321 0273 00 8010100 02999 RES FXD FILM 6 81K OHM 1 0 125W TC TO 07718 58100 15 182288 321 0353 00 8030000 RES FXO FILM 46 4K OHM 125 0 125W TC TO 07718 46401 15 182289 321 0193 00 8010100 8029999 RES FILM 1K OHM 1 0 125W TC TO 19701 5033 7 38 REV JUL 1987 t No AlSAIR2289 15 1 2290 1 1 2291 15 1 2291 A15AIR2292 1 1 2292 1 5 1 2293 A15A1R2293 15 182294 15 1 2295 15 152296 A15A1R2297 A15A1R2297 15 182298 A15A1R2298 A15AIR2299 15 183486 154152110 ALSALTP2112 15 17 2113 15 17 2115 15 1 2117 A15AITP2119 15 17 2129 ALSAITP2131 A15A1TP2133 15 17 2135 15 1
268. MODE operation where the slowest trace tends to be the brightest The A and B INTENSITY controls allow individual adjustment of the intensity of the traces produced by the time base units in the HORIZ and HORIZ compartments Triggering is not as critical in the CHOP horizontal mode as in ALT if one of the units is not triggered properly only the trace from the untriggered time base unit is missing from the display The other trace is presented in the normal manner See Trigger Source and Vertical Trace Separation for information on Operating Instructions 7904A positioning the trace produced by the B HORIZ unit in relation to the trace from the A HORIZ unit VERTICAL TRACE SEPARATION When one of the dual sweep horizontal modes is selected the VERT TRACE SEPARATION B control allows the trace produced by the B HORIZ sweep to be positioned above or below the trace produced by the A HORIZ sweep To use the control first position the trace produced by the HORIZ plug in unit Then adjust the VERT TRACE SEPARATION B control to move the trace produced by the B HORIZ plug in unit away from the A HORIZ display If both waveforms are larger than four divisions in amplitude the displays can only be positioned so they do not directly overlap since each waveform cannot be positioned to a unique area of the crt TRIGGER SOURCE The A and B TRIGGER SOURCE switches select the internal trigger signals for the A HORIZ and B HORI
269. N 37421 GARDEN CITY PARK NY 11040 SECAUCUS NJ 07094 KIRKLAND WA 98034 7716 WESTLAKE VILLAGE CA 91361 ST PAUL MN 55107 SCHAUMBURG IL 60195 NORTH ADAMS MA 01247 IRVINE CA 92713 SALEM MA 01970 TUCSON ARIZONA 85705 FL PASO TX 79915 VISALIA CA 93291 GRAFTON WI 53024 ST LOUIS 63178 ERIE 16512 FULLERTON 92634 WASECA MN 56093 PHILADELPHIA PA 19108 COMPTON CA 90224 PRINCETON IN 47670 WARMINSTER PA 18974 BEAVERTON OR 97077 MORRISTOWN NJ 07960 CHICAGO Ii 60630 OGALLALA NE 69153 COLUMBUS NE 68601 HILLSBORO NH 03244 JAPAN EVERETT 98201 KENT WA 98032 KANAGAMA 228 JAPAN OR 97006 KENT WA 98032 7 9 Replaceable Electrical Parts 79044 A24 A25 A26 A27 A28 A28 7 4 Tektronix nt No Part No 670 8060 00 670 8060 01 670 5227 01 670 4778 01 670 4778 01 670 4773 03 670 4775 00 670 4775 01 670 4775 02 670 8051 00 670 8051 00 670 8054 00 670 8055 00 670 4641 00 520 0283 01 670 5959 03 670 5959 04 670 4777 20 670 4776 20 672 0572 00 6 2 0572 01 672 0572 02 672 0572 05 670 1900 06 670 8620 00 670 8620 01 670 8620 04 670 4769 20 670 1633 00 570 7922 00 670 1634 00 670 5841 20 670 5841 21 670 5834 20 670 5834 21 670 5960 03 570 5960 04 670 6259 01 670 6259 02 119 1048 00 670 8052 00 670 8053 00 670 4346 00 670 1632 05 670 1632 06 Serial Assembly No Effective Dscont 8010100 8042058 B010100 B01094
270. ND ROW DECODERS The Column Decoder U2244 and How Decoder U2185 sense the magnitude of the analog voltages at their inputs pin 10 and produce a binary output on one of ten lines corresponding to the column or row data encoded by the plug in unit These outputs provide the Column Digital Data and Row Digital Data which is used by the Character Generator stages to select the desired character for display on the crt The column and row data is also used throughout the Readout System to perform other functions 3 33 Theory of Operation 7904A The input current at pin 9 of the Column Decoder stage is steered to only one of the ten Column Digital Data outputs When Display Skip signal is present collector of 02225 pin 9 is pulled HI through CR2226 This ensures that no current is connected to the Character Generator stage under this condition Notice the corresponding input on the Row Decoder This input is connected to ground and causes only one of the ten row outputs to saturate to ground The network at the input of the Row Decoder made up of Q2153 and its associated components is a Row 14 detector that produces the Jump Command This row current is encoded by special purpose plug ins to cause ali or part of a word to be jumped Whenever row 14 13 units of row current or 1 3 milliamperes is encoded the base of Q2153 is pulled negative enough so that this transistor is reverse biased to produce a Jump Command output
271. NDITIONS 7904A Controls HORIZONTAL MODE INTENSITY CALIBRATOR CALIBRATOR Coaxial Amplifier o gt s 3 e Time Base Thine Base Test Equipment Controis Amplifier Unit Deflection Factor Time Base Sweep Rate Triggering 20 us div Auto AC External Delaying Time Base Sweep 0 2 ms div Triggering Auto AC Internal B Delay Mode B Starts After Dly Delay Time Midrange 4593 507 a Center the square wave display on the crt graticule using the amplifier Position control and set the A INTENSITY contro for a normal viewing level b Set the delaying time base unit Triggering controls for a stable display Set the delaying time base unit Delay Time control to mid range d EXAMINE the crt display while rotating the B CONTRAST adjustment R2015 front panel screwdriver adjustment through its entire range Notice the change in the intensity of the intensified portion of the waveform e ADJUST the B CONTRAST adjustment R2015 for a well defined intensified zone on the displayed trace 5 42 B7 CHECK ADJUST GEOMETRY AND ADJUST TRACE ALIGNMENT FOCUS A20R155 20855 A2R2025 A20R143 A29R122 NOTE If the preceding step was not performed first perform step B1 then proceed B7 SETUP CONDITIONS 7904A Controls VERTICAL MODE HORIZONTAL MODE A and B INTENSITY Precision DC Voltmeter DVM Signal Standardi
272. NG STUDS PLACE LOCKWASHERS ON MOUNTING STUDS WITH TEETH AWAY FROM POWER TRANSISTOR GL XO SECURE NUT ON MOUNTING STUD C2314 33 Figure 4 13 Correct placement of power transistor and mounting hardware on rear heatsink 4 21 79044 12 Install the chassis on the power supply unit 13 Connect the multi pin connectors to the board Match the index arrow on the pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown in the circuit board illustration in Section 8 Diagrams and Circuit Board Illustrations 14 Replace the power supply unit in the instrument A12 Control Rectifier Circuit Board n exploded view drawing of the power supply unit is given in Section 9 Replaceable Mechanical Parts at the rear of this manual To remove the A12 Control Rectifier board use the following procedure 1 Slide the power supply unit out of the instrument see Power Supply Unit Removal 2 Remove the protective cover from the power supply unit see Access to Components in the Power Supply Unit 3 Remove the A22 Low Voltage Regulator board with attached chassis as previously described 4 Disconnect the multi pin connectors from the A12 Contro Rectifier board Note the location of the pin connectors so they can be correctly replaced 5 Remove the 2 plastic screws which hold the circuit board shieid to the A23 Power Supply inverter board
273. NGE ST DARLINGTON SC 29532 SUBSIDIARY OF NYTRONICS INC 00779 AMP INC P 0 BOX 3608 HARRISBURG PA 17105 00853 SANGAMO WESTON INC SANGAMO RD PICKENS SC 29671 SANGAMO CAPACITOR DIV P 0 BOX 128 01121 ALLEN BRADLEY CO 1201 SOUTH 2ND ST MILWAUKEE WI 53204 01295 INSTRUMENTS INC 13500 N CENTRAL EXPRESSWAY DALLAS TX 75265 SEMICONDUCTOR GROUP P 0 BOX 225012 M S 49 02111 SPECTROL ELECTRONICS CORP 17070 GALE AVE CITY OF INDUSTRY CA 91749 SUB OF CARRIER CORP P 0 BOX 1220 02114 ELECTRONIC CORP 5083 KINGS HWY SAUGERTIES NY 12477 FERROXCUBE DIV 02735 RCA CORP ROUTE 202 SOMERVILLE NJ 08876 SOLID STATE DIVISION 02777 ENGINEERING CO 12900 FOOTHILL BLVD SAN FERNANDO CA 91342 03508 GENERAL ELECTRIC CO W GENESEE ST AUBURN NY 13021 SEMI CONDUCTOR PRODUCTS DEPT 04099 INC FORESIGHT INDUSTRIAL PARK GRAND JUNCTION CO 81501 P 0 BOX 2164 04222 CERAMICS DIV OF AVX CORP 19TH AVE SOUTH MYRTLE BEACH SC 29577 P 0 BOX 867 04713 MOTOROLA INC 5005 E MCDOWELL RD PHOENIX AZ 85008 SEMICONDUCTOR GROUP 05387 UNION CARBIDE CORP MATERIALS SYSTEMS 11901 MADISON AVE CLEVELAND 44101 DIV 05828 GENERAL INSTRUMENT CORP 600 W JOHN ST HICKSVILLE NY 11802 GOVERNMENT SYSTEMS DIV 07263 FAIRCHILD CAMERA AND INSTRUMENT CORP 464 ELLIS ST MOUNTAIN VIEW CA 94042 SEMICONDUCTOR DIV 07716 RW INC 2850 MT PLEASANT AVE BURLINGTON 52601 TRW ELECTRONICS COMPONENTS TRW IRC FIXED RESISTORS BURLINGTON 11236 CTS OF BERNE INC 406 PARR ROAD BERN
274. NPN SILICON TO 220 04713 TRANSISTOR PNP SI 10 220 04713 TRANSISTOR NPN SI 70 220 02735 TRANSISTOR PNP ST 70 220 04713 TRANSISTOR NPN SI SELECTED TO 127 04713 TRANSISTOR SCREENED 80009 RES FXD CMPSN 1M OHM 5 1W 01121 SWITCH SLIDE DPDT 3A 125VAC 82389 SWITCH SLIDE DPTT 0 5A 125VAC 82389 XFMR PWR STPDN HIGH FREQUENCY 80009 620 0283 01 3607560 3607560 6 0738 602DX262G035AA2B MTH C4 4 F 11935 6 108 0761 00 286044 5451946 541946 541973 26044 SJE1973 5 924 151 0477 01 681055 462061 110 1007 120 1183 00 7 21 Replaceable Electrical Parts 7904A Tektronix t No Part No 12 1 570 5959 03 8 010100 12 1 670 5959 04 8031833 12 1 52 283 0003 00 89010100 12 1 52 285 1340 00 8 031833 12 1 54 290 0573 00 12 1 55 283 0028 00 12 1 64 290 0263 00 A12A1C66 283 0003 00 010100 12 1 66 285 1340 00 8031833 12 1 67 290 0523 00 010100 Ai2A1C67 290 0573 00 8031833 A12A1C70 290 0534 00 8010100 12 1 70 285 1338 00 8031833 12 1 71 290 0534 00 8010100 12 1 71 285 1338 00 8031833 A12A1C74 283 0594 00 12 1 77 283 0060 00 8010100 12 1 77 283 0084 00 8031833 12 1 78 283 0060 00 8010100 12 1 78 283 0084 00 8 031833 12 1 80 283 0080 00 010100 12 1 86 290 0580 00 12 1 90 290 0778 00 A12A1C92 285 1123 00 12 1 94 285 0695 00 12 1 121 285 0892 00 12 1 124 290 0758 00 12 1 125 290 0758 00 A12A1C132
275. NSISTOR SCREENED 04713 ST919H 210183 151 0274 01 TRANSISTOR SCREENED 04713 557394 A210184 151 0192 03 TRANSISTOR SELECTED 80009 151 0192 03 2184 307 0106 00 RES FXD CMPSN 4 7 5 0 25 01121 4765 2188 315 0100 00 RES FXD FILM 10 OHM 595 0 25W 19701 5043CX10RR00J 2189 307 0107 00 RES CMPSN 5 6 5 0 25 01121 CB5665 21811 307 0106 00 RES FXD CMPSN 4 7 OHM 52 0 25W 01121 4765 A21R12 315 0100 00 RES FXO FILM 10 OHM 525 0 25W 19701 5043 108 00 21831 321 0289 00 RES FXD FILM 10 0 OHM 126 0 125W TC TO 19701 5033 010 21835 315 0221 00 RES FXD FILM 220 0HM 52 0 25W 57668 NTR25J E220 21836 315 0102 00 RES FILM 1K OHM 5 0 250 57668 25 01 0 21837 321 0289 00 RES FXD FILM 10 0K OHM 1 0 125W TC T0 19701 5033 010 21843 321 0333 00 RES FXD FILM 28 7K 1 0 1259 70 19701 5043 D28K70F 21861 321 0341 00 RES FILM 34 8K 1 0 125 4 70 19701 5043 34 80 A2 R62 321 0193 00 RES FILM 1K OHM 12 0 1254 TC TO 19701 5033ED1K00F 21863 311 1757 00 RES VAR NONWW 2 5K OHM 10 5 LIN CERMET 73138 82PR2 5K 124C A2ZiR64 315 0471 00 RES FXD F1LM 470 5 0 25 57668 NTR25J E470E A21R65 321 0254 00 RES FXD FILM 4 32K OHM 1 0 125W TC TO 07716 43200 A2iR67 315 0102 00 RES FXO FILM 1K OHM 5 0 25W 57668 252 01 0 21870 311 1267 00 RES VAR
276. O 19701 5033ED499ROF 148209 321 0184 00 RES FILM 499 OHM 1 0 125W 0 19701 5033ED499ROF A14R212 325 0053 00 RES FXD FILM 50 OHM 126 0 05V TC T0 91637 148213 325 0053 00 RES 50 OHM 12 0 05M 0 91637 50 5 14 214 325 0053 00 RES FILM 50 OHM 125 0 054 TC TO 91637 CMF50 F5OROOF 148216 325 0053 00 RES FXD FILM 50 OHM 15 0 054 TC TO 91637 CMF50 FSOROOF 148217 325 0053 00 RES 50 OHM 125 0 054 TC TO 91637 CMF50 FSOROOF A14R218 325 0053 00 RES FXD FTLM 50 OHM 125 0 05W TC TO 91637 CMF50 F50RDOF 148032 321 0202 00 RES FXD FILM 1 24K 126 0 1254 TC TO 24546 NA55D1241F A14R233 322 0111 00 RES F1LM 140 GHM 1 0 25W TC TO 91637 MFF1421G140ROF A14R234 322 0170 00 RES FXD FILM 576 0HM 12 0 25W TC TO 75042 CEBTO 5760F A14R235 321 0202 00 RES FILM 1 24K OHM 1 0 125W TC TO 24546 55 1241 A14R236 321 0147 00 RES FXD FILM 332 OHM 1 0 125W TC TO 07718 CEAD332ROF REV JUL 1987 7 29 Replaceable Electrical Parts 7904A Tektronix _ Serial Assembly No Mfr t No Part No Effective _ Dscont Name amp Description Code Mfr Part No 148237 315 0103 00 RES FXD FILM LOK OHM 5X 0 250 19701 5043 10 00 A14R238 321 0155 00 RES FILM 402 0HM 12 0 125W TC TO 07716 CEADAO2ROF A14R239 321 0085 00 RES FXO FILM 75 OHM 12 0 125W TC TO 57668
277. O 92 TRANSISTOR NPN SI 10 18 TRANSISTOR NPN ST TO 18 RES FXD FILM 10 OHM 556 0 25W RES FXD FILM 20K OHM 5 0 25W RES FXD FILM 1K OHM 15 0 125W TC TO RES FXO FILM 22K 5 0 25 RES FXO FILM 1K 1 0 125W TC TO RES FXD FILM 332 OHM 15 0 125 0 RES FXD FILM 3 01K OHM 125 0 1254 TC TO RES FXD FILM 9 1K OHM 5 0 25M RES FXD FILM 5 IK OHM 55 0 25W RES FILM 200 5 0 25 RES FXD FILM 100 5 0 258 RES FXD FILM 5 1K OHM 54 0 25W RES FXD FILM 3 3K OHM 5 6 0 25M RES FXD FILM 2K OHM 5 0 250 RES FXD FILM 6 8K OHM 5 0 25W RES FXD F1LM 30K OHM 54 0 25 RES FXD FILM 5 1K OHM 525 0 25M RES 7 5K OHM 5 0 25W RES FXO FILM 270 OHM 54 0 25W RES FXD FILM 2 2K OHM 5 0 25W RES FXD FILM 270 OHM 5 0 258 RES FXD FILM 3 OHM 55 0 25 RES FXD FILM 3 3K OHM 5 5 0 25W RES FXD FILM 1 5K OHM 54 0 25W RES FXD FILM 1K OHM 54 0 25M RES FXD FILM 100 0HM 54 0 25W RES FILM IK OHM 55 0 254 RES FXD FILM 3 3K OHM 5 0 25M RES FXD FILM 100 OHM 54 0 25W RES FXD FILM 2K OHM 55 0 25W RES FXD FILM LOK OHM 54 0 254 RES FXD FILM 3K OHM 55 0 25W Mfr Code 76493 76493 76493 76493 TK1345 TK1345 TK1345 TK1345 04713 04713 80008 04713 04713 04713 04713 04713 04713 04713 80009 04713 04713 80009 04713 80009 04713 04713
278. ONDITIONS 7904A Controis Time Mark Generator Zi 5 i 2 9 lt Coaxial Cable Test Equipment Controls Time Base Triggering Auto AC Internal Sweep Rate 1 ms div Time Mark Generator 1 ms markers 4593 420 Set the amplifier deflection factor for approximately two divisions of display set the time base Triggering Level as necessary for a stable display Examine the crt display for one time marker per division over the center eight divisions Set the time base unit front panel Swp Cal adjustment for one time marker per division over the center eight divisions CHECK refer to the Performance Check procedures in the time base unit instruction service manual to check high frequency timing and accuracy to 0 5 ns 500 ps is the fastest calibrated sweep rate for the 7904A 5 24 NOTE If the preceding step was not performed first perform step D1 then proceed D4 SETUP CONDITIONS 7904A Controls Low Frequency Sine Wave Generator 8 amp E 4 Aux In Connector BNC T Connector Coaxial Cable Test Equipment Controls Amplifier Units Volts Div Coupling REPE E DC 4593 421 Set the low frequency sine wave generator for eight divisions of vertical and horizontal deflection at 35 kHz Set the Amplifier unit controls to match the vertical and horizontal deflection display for a Liss
279. ONTAL MODE switch to A Set the READOUT control to OFF BEAMFINDER 38 39 40 Set the deflection factor of the left amplifier unit to 10 millivolts division and the calibrator for a 4 V output Notice that the square wave display is not visible since the deflection exceeds the scan area of the crt Press the BEAMFINDER button notice that the display is returned to the viewing area in compressed form Release the BEAMFINDER button and notice that the display again disappears from the viewing area With the BEAMFINDER pushed in adjust the Position control of the displayed amplifier unit to position the compressed display near graticule center Then increase the amplifier unit deflection 2 7 Operating instructions 7904A factor unti the display is reduced to about 2 divisions vertically Release the BEAMFINDER button and observe that the display remains within the viewing area CALIBRATOR 41 Select different CALIBRATOR pushbuttons labeled 4 V 0 4 V and 40 mV and notice that the displayed signal changes accordingly CALIBRATOR output must be terminated into more than a 100 kilohm load for stated output When the CALIBRATOR output is terminated into 50 ohms the output is 0 1 times the stated output Disconnect the CALIBRATOR signal Z AXIS INPUT 42 lf an external signal is available e g sine wave signal from a function generator the operation of the Z AXIS INPUT can be demonstrated Connect
280. PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT DGTL CHANNEL SWITCH MICROCKT LINEAR OPNL AMPL SEL MICROCKT LINEAR OPNL AMPL SEL Mfr Code 01121 19701 19701 57668 01121 01121 57668 57668 01121 07716 19701 57668 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 27014 27014 27014 27014 80009 04713 04713 Mfr Part 81035 5043 D3K570F 5033 D16K20F NTR25J EO2K7 ORDER BY DESCR ORDER BY DESCR NTR25J E470E NTR2SJEO1KO EB33G5 CEAD78700F 5033ED22K10F NTR25J EQ5K6 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0578 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 LF351N GLEAL34 LF351N GLEA134 LF351N GLEA134 LF351N GLEA134 155 0173 05 1741 1 MC1741CPl 7 49 Replaceable Electrical Parts 7904A Tektronix No Part No A17 570 1633 00 A17CB03 283 0603 00 A17C804 281 0118 00 A17C806 283 0677 00 A17C807 283 0868 00 A17C808 283 0668 00 A17C809 283 0677 00 17 813 283 0603 00 Al7C814 281 0118 00 A17C816 283 0677 00 17 817 283 0668 00 A17C818 283 0668 00 17 819 283 0677 00 17 801 152 0141 02 AL7CR811 152 0141 02 A17K802 148 0034 0
281. PSN 4 7 5 0 25 01121 CB 4765 A28R220 315 0300 00 RES FILM 30 OHM 5 0 25W 19701 5043CX30R00J A28R221 321 0155 00 RES FILM 402 OHM 1 0 125W TC T0 07716 CEAD402ROF A28R230 311 0634 00 RES VAR 500 OM 0 SW 32997 3329 158 501 A28R231 315 0300 00 RES FXD FILM 30 OHM 5 0 25W 19701 5043 30800 A28R232 321 0119 00 RES FILM 169 0HM 12 0 125W TC TO 07718 CEADLESROF 288240 311 0613 00 RES VAR LOOK OHM 0 50 32997 3329H G48 104 A28R300 321 0167 00 RES FILM 536 OHM 1 0 125W TC T0 07716 CEADSSGROF A28R301 321 0228 00 RES FILM 2 32K OHM 1 0 125W TC TO 19701 5043ED2K32F A28R302 315 0473 00 RES FXD FILM 47K 5 0 250 57668 NTR25J E47KO A28R310 321 0228 00 RES FXD FILM 2 32K OHM 1 0 125W TC TO 19701 5043 2 32 288311 321 0120 00 RES FXD FILM 174 OHM 12 0 125W TC TO 07716 CEAD174ROF A28R312 311 0605 00 RES VAR TRMR 200 OHM 0 SW 32997 3329 048 201 A28R320 315 0300 00 RES FILM 30 OHM 54 0 25W 19701 5043CX30R00J A28R321 315 0101 00 RES FILM 100 OHM 53 0 259 5 668 NTR2SJ E 100E A28R322 321 0185 00 RES FXD F1LM 825 OHM 1 0 125W TC TO 07716 CEAD825RO0F A28R330 321 0119 00 RES FILM 169 OHM 13 0 0 07716 CEADI69ROF A28R331 315 0101 00 RES FILM 100 5 0 2 57668 NTR25J E 100 A28R340 311 0605 00 RES VAR NONWW 200 OHM
282. Performance Check A POWER SUPPLY Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 16 Screwdriver Phillips 9 Plug In Extender optional for this procedure 1 POWER SUPPLY PRELIMINARY SETUP a Perform the Adjustment and Performance Check 5 Precision DC Voltmeter DVM 19 Tool Alignment A2 ADJUST PREREGULATOR A12R93 NOTE Power Up Sequence Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for First perform step 1 then proceed A2 SETUP CONDITIONS 7904A Controls No change in settings any modifications which may affect this procedure foldout page in Section 8 Diagrams and Circuit Board l lustrations c See the TE d Set the 7904A controls as follows Precision DC Voltmeter DVM E TM Ter Wa 94 4 4 9 od For a 3 464 1 VERT TRACE SEPARATION B Midrange LoT dod o TRIGGER SOURCE VERT MODE A INTENSITY Fully counterclockwise deed HORIZONTAL MODE A B INTENSITY Fully counterclockwise n be OU B TRIGGER SOURCE VERT MODE Appropriate range for FOCUS crues tar Seer ates Midrange voltage to be measured READOUT intensity OFF in detent 4593 6500 GRAT ILLUM Fully counterclockwise CONTROL ILLUM MEDIUM rea
283. R2246 152 0333 00 A27CR2247 152 0333 00 A27CR2248 152 0333 00 27 82249 152 0333 00 A27CR2250 152 0333 00 A27CR2251 152 0333 00 A27CR2252 152 0333 00 A27CR2253 152 0333 00 A27CR2254 152 0333 00 A27CR2255 152 0333 00 A27CR2256 152 0333 00 A27CR2257 152 0333 00 A27CR2258 152 0333 00 A27CR2259 152 0333 00 A27CR2260 152 0333 00 A27CR2261 152 0333 00 A27CR2262 152 0333 00 A27CR2263 152 0333 00 A27CR2264 152 0333 00 A27CR2265 152 0333 00 A27CR2265 152 0333 00 A27CR2267 152 0333 00 A27P2265 131 0589 00 A27P2266 131 0589 00 7 64 Serial Assembly Effective Dscont Name amp Description CIRCUIT BD ASSY READOUT PROTECTION 1 PART OF 672 0572 00 SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DT SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND OVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DYC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC Di SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SW SI 55V 200MA D0 35 SW S1 55V 200MA D0 35 SW ST 55V 200MA 00 35 SW 1 55V 200MA 00 35 SW SI 55V 200MA 00 35 SW S1 55V 200MA 00 35 SW S1 55V 200MA 00 35 SW S1 55V
284. R230 5 Adjust Readout Centering and Gain A288114 28 101 6 Check Adjust High Frequency Timing A28C810 A28C850 A28C310 A28C340 A28R312 A28R340 A28C922 7 Adjust Horizontal Readout Jitter A2BB2d0 2 pe oles SERA 8 Check Adjust X Y Delay Compensation 17 804 17 814 4 o o 9 os om n m ot t t m mo o ertt n 8 F VERTICAL SYSTEM 1 Vertical System Preliminary Setup 2 Adjust Vertical Amplifier Centering A18R736 16 535 3 Check Adjust Vertical Amplifier Gain ATOR TT OU He E SENA 4 Check Vertical Low Frequency s ed re e oves ex tac SA OA E 5 Adjust Thermal Compensations A18R130 A18C200 A18R238 A18R335 A18R237 A18R132 A18R131 4 oh a oo t a n n Checks and Adjustment 7904A Part ll Adjustment and Performance Check Adjust Channel Switch Compensation A16C538 A16R530 A16R525 A16R520 A16R515 A16R512 A16C638 A16R630 A16R625 A16R620 A16R615 A16R612 Adjust High Frequency Compensation A18R404 A18R405 A18C401 R83 A18R215 A18C215 181100 Check Vertical Amplifier 500 MHz Gain Check Vertical Channel Isolation Check Vertical Display Modes Check Vertical Trace Separation B DAY Vd
285. RES FILM 154K OHM 1 0 1254 TC TO RES FXD FILM 18K OHM 5 0 25W RES FXD FILM 73 2K OHM 17 0 1250 TC TO RES FILM 3 6K OHM 5 0 258 RES FXD FILM 6 2K OHM 52 0 25W RES FXD FILM LOK OHM 52 0 25W RES FILM 300 OHM 5 5 0 25W RES FILM 43 2K OHM 17 0 125W TC TO RES FILM 5 1K OHM 545 0 25W RES FILM 43 2K OM 15 0 125W TC TO RES FXD FILM 2 2K OHM 5 0 25W RES FILM 620 OHM 54 0 25W RES FILM 1 5K OHM 55 0 25W RES FXD FILM 1K OHM 55 0 25W RES FXD FILM 750 5 0 25 4 RES FXD FILM 750 OHM 5 0 25W RES FXD FILM 1K OHM 55 0 259 RES FXD FILM 750 OHM 5 0 25W RES FXD FILM 750 OHM 5 0 25W RES FXD FILM 1K OHM 5 0 25M RES FXB FILM 750 OHM 5 0 25W RES FXD FILM 750 OHM 5 0 25W RES FXD FILM 1K OHM 5 0 25M RES FXO FILM 750 OHM 5 0 25W RES FXD FILM 750 OHM 5 5 0 25W RES FXD FILM 510 OHM 54 0 25W RES FILM 510 OHM 5 0 25W RES FXD FILM 510 0HM 545 0 25W RES FXO FILM 102K OHM 125 0 12 TC TO RES FXD FILM 5 23K 1 0 1254 0 RES FXD FILM 56 2K OHM 17 0 125W TC TO RES VAR NONW 500 OHM G SW RES VAR NONW 500 OHM 205 0 50 LINEAR RES FILM 5 23K 0HM 1 0 1254 TC TO RES NTWK FXD F1 4 7K OHM 20 9 RES RES FILM 1K OHM 55 0 25V RES FILM 51K OHM 54 0 25W RES FXD FILM
286. S 7904A Controis No change in settings amp bag 58 E 19 5 Test Equipment Controls Time Base Triggering Sweep Rate Auto AC Internal 5 us div Signal Standardizer Vert or Horiz Com Mode 4590 5284 a Short TP610 to TP750 on the A28 Horizontal Amplifier board with a 12 inch jumper wire b EXAMINE the vertical trace it should be within 0 5 division of the center vertical graticule line c ADJUST Limit CTR adjustment R630 on the A28 Horizontal Amplifier Board to align the displayed trace with the center vertical graticule line d Remove the jumper wire from TP610 and TP750 5 55 Checks and Adjustment 7904A Part and Performance Check E3 ADJUST HORIZONTAL AMPLIFIER CENTERING A28R121 NOTE If the preceding step was not performed first perform step E1 then proceed E4 CHECK ADJUST HORIZONTAL GAIN AND LOW FREQUENCY LINEARITY A28R230 NOTE If the preceding step was not performed first perform step E1 then proceed E3 SETUP CONDITIONS E4 SETUP CONDITIONS 7904A Controls 7904A Controls No change in settings No change in settings Signal Standardizer Time Base I Signal Standardizer Ld m Test Eguipment Controls Time Base Triggering Auto AC Internal Sweep Rate 5 us div Test Equipment Controls Time Base Triggering Auto AC internal Sweep Rate 5 us div Signal Standardizer
287. SISTOR NPN ST TO 78 07263 5 12141 A15A102223 151 0190 00 8010100 8029999 TRANSISTOR NPN SI TO 92 80009 151 0190 00 A15A102223 151 0190 00 8030000 TRANSISTOR NPN SI TO 92 80009 151 0190 00 A15A102225 151 0188 00 8010100 8029999 TRANSISTOR 51 70 92 80009 151 0188 00 15 102226 151 0190 00 8030000 TRANSISTOR NPN SI TO 92 80009 151 0190 00 A15A102227 151 0190 00 B030000 TRANSISTOR NPN SI TO 92 80009 151 0190 00 A15A102229 151 0190 00 010100 8029999 TRANSISTOR NPN SI TO 92 80009 151 0190 00 15 102229 151 0188 00 030000 TRANSISTOR PNP SI 70 92 80009 151 0188 00 A15A102240 151 0190 00 TRANSISTOR NPN SI TO 92 80009 151 0190 00 15 102243 151 0190 00 030000 TRANSISTOR 51 10 92 80009 151 0190 00 15 102250 151 0188 00 030000 TRANSISTOR SI TO 92 80009 151 0188 00 A15A102255 151 1021 00 8030000 TRANSISTOR ST T0 18 80009 151 1021 00 15 102286 151 0188 00 8010100 029999 TRANSISTOR SI TO 92 80009 151 0188 00 A15A102287 151 0188 00 8010100 8029999 TRANSISTOR SI TO 92 80009 151 0188 00 A15A102296 151 0188 00 8010100 B029999 TRANSISTOR PNP ST TO 92 80009 151 0188 00 A15A102296 151 1021 00 8030000 TRANSISTOR N CHAN ST 10 18 80009 151 1021 00 A15A102299 151 0188 00 8010100 B029999 TRANSISTOR PNP S1 TO 92 80009 151 0188 00 15 182101 315 0682 00 RES FXD FILM 6 8K OHM 53 0 25W 57668 NTR25J EOSK8 15 162102 315 0103 00 RES
288. SSY GRATICULE LAMPS 80009 670 0702 06 A30D5304 150 0097 00 LAMP INCAND 6 3V 0 2A 47381 WIRE LEADS 92966 7381 A3005305 150 0097 00 LAMP INCAND 5 3V 0 2A 7381 WIRE LEADS 92966 7381 3005306 150 0097 00 LAMP INCAND 5 3V 0 2A 47381 WIRE LEADS 92966 7381 REV JUL 1987 7 69 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr t No Part No Effective _ Dscont Name amp Description Code Mfr Part No A31 570 8046 00 CIRCUIT BD ASSY FLEX CON 80009 670 8046 00 PART OF 672 1176 00 NO ELEC PARTS 7 70 REV JUL 1987 t No Part C8i 283 0003 00 C154 290 0898 00 C154 290 0898 01 05308 150 0121 02 052002 150 0048 01 052003 150 0048 01 J130 131 0755 01 4497 131 1315 01 J1925 131 1315 01 J1944 131 1315 01 21 108 0544 00 121 108 0544 01 122 108 0605 00 L156 108 0337 00 11725 108 0544 00 L1730 108 0605 00 LR780 108 0685 00 8784 108 0685 00 R83 307 0292 24 S10 260 1709 00 V21 154 0644 05 Voi 154 0893 05 Vei 154 0661 05 21 154 0661 09 V21 154 0644 09 REV JUL 1987 Serial Assembly No Effective _ Dscont B010100 B031832 B031833 8010100 B010579 B010580 8010100 B031782 B031783 Replaceable Electrical Parts 7904A amp Description CAP FXD CER DI1 0 01UF 80 20 150V CAP FXD ELCTLT 2600UF 75 1055 35V CAP FXD ELCTLT 2600UF 75 10 35 LAMP CARTRIDGE 5V 0 06A GREEN LENS PART OF 198 3762 LAMP INCAND 5V 0 06A 683 AGED amp SEL L
289. ST 400 V 400MA Ai SEMICOND DVC DI RECT SI 400V 1A SEMICOND DVC DT RECT SI 400V 1A SEMICOND DVC DI SW SI 175V 0 1A 00 35 SEMICOND 0 01 584 51 175 0 1 00 35 SEMICOND DVC DI RECT SI 400 V 400MA Ai SEMICOND DVC DI RECT SI 400V 1A SEMICOND DVC DI RECT SI 400 V 400MA SEMICOND DVC DI RECT S1 400V 1A SEMICOND DVC DI 5SV S1 175V 0 1A D0 35 SEMICOND DVC DI RECT SI 20V 1A A59 SEMICOND OVC DI RECT SI 400 V 400MA 1 LAMP GLOW 90V MAX 0 AID T WIRE LD ARSR ELEC SURGE 230 GAS FILLED ARSR ELEC SURGE 230 GAS FILLED COIL RF FIXED 140UH TRANSISTOR UJT S1 T0 98 TRANSISTOR NPN SILICON 10 220 TRANSISTOR NPN SILICON T0 220 TRANSISTOR NPN SI T0 92 TRANSISTOR PNP ST TO 92 TRANSISTOR NPN SI T0 39 RES FXD CMPSN 27 OHM 10 1W RES FXD WW 6 8 5 2 5 RES FXO CMPSN 47K OHM 10 1W RES CMPSN 180K OHM 5 1W RES FXD WW 6 8 OHM 5 2 SW RES FXD CMPSN 47K OHM 10 1W RES FXD CMPSN 5 64 OHM 10 0 W RES FXD CMPSN 150K OHM 10 1W RES FXD FILM 470 OHM 5 0 25W RES FXD CMPSN 10 5 1W RES FXD FILM 22 OHM 5 0 250 RES FXD FILM LOK OHM 555 0 25W RES FXD FILM 20 OHM 55 0 5 RES FXD FILM 3 3K OHM 52 0 25W RES FXD FILM 20 OHM 5 0 SW Mfr Code Mfr Part No 80009 80009 59650 14752 59660 04222 60705 51406 60705 51406 04099 55680 59660 60705 51406 55680 04222 54473 14936 05828 12968 04713 04
290. Selector Board to optimize test oscilloscope square wave display 5 53 Checks and Adjustment 7904A Part Hl Adjustment and Performance Check NOTE If the preceding step was not performed first perform step D1 then proceed 05 SETUP CONDITIONS 7904A Controls VERTICAL MODE HORIZONTAL MODE A TRIGGER SOURCE B TRIGGER SOURCE VERT MODE VERT MODE Calibrator Coaxial Cable Signal Standardizer B Time Base 5 5 4 Test Equipment Controls Signal Standardizer Vert or Horiz Step Resp A Time Base Sweep 0 2 ms div Triggering Auto AC Internal Magnifier B Time Base Sweep 0 2 ms div Triggering Auto AC Internal Magnifier 4593 521 Set the A INTENSITY control for a visible display Set the amplifier for a 2 division display in the upper half of the graticule area Use the time base Triggering Level control to trigger the display Set the VERTICAL MODE switch to RIGHT Set the signal standardizer Amplitude and Position controls for a 2 division display in the lower half of the graticule area Set the VERTICAL MODE switch to ALT crt display for 1 kHz and 10 kHz triggered waveforms adjust the time base unit Triggering Level controis as necessary Set the VERTICAL MODE switch to ADD CHECK the crt display for a triggered waveform Set the VERTICAL MODE swi
291. T PART OF 672 0572 CIRCUIT BD ASSY VERTICAL CHANNEL SWITCH CIRCUIT BD ASSY X Y DELAY COMPENSATION OPTION 02 ONLY CIRCUIT BD ASSY VERT AMP PART OF 672 1176 00 CIRCUIT BD ASSY HORIZONTAL INTERCONNECT REMOVE FOR OPTION 02 CIRCUIT BD ASSY HV CIRCUIT BD ASSY HY CIRCUIT BD ASSY Z AXIS CIRCUIT BD ASSY Z AXIS CIRCUIT 8D ASSY LOW VOLTAGE REGULATOR CIRCUIT 8D ASSY LV REGULATOR CIRCUIT BD ASSY INVERTER CIRCUIT BD ASSY INVERTER PART OF 620 0283 02 DELAY LINE ELEC 65NS 50 OHMS NO ELECTRICAL PARTS CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT BD ASSY FRONT PANEL DISPLAY CIRCUIT ASSY READOUT PROTECTION 1 PART OF 672 0572 00 CIRCUIT BD ASSY MAIN HORIZONTAL AMP CIRCUIT BD ASSY HORIZONTAL AMPLIFIER Mfr Code Mfr Part No 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 80009 670 8060 00 670 8060 01 670 5227 01 670 4778 01 670 4778 01 670 4773 03 670 4775 00 670 4775 01 670 4775 02 670 8051 00 670 8051 00 570 8054 00 670 8055 00 670 4641 00 620 0283 01 670 5959 03 670 5959 04 670 4777 20 670 4776 20 672 0572 00 672 0572 01 572 0572 02 572 0572 05 670 1900 06 670 8620 00 670 8620 01 670
292. T or CHOP positions of the HORIZONTAL MODE switch the output level at pin 6 is the same as the Display B Command level at pin 7 The Display B Command level is produced by inverting the Display B Command from the Horizontal Binary stage Therefore the repetition rate of the output signal is the same as the Display B Command With the VERTICAL MODE switch set to ALT and the A time base unit set for nondelayed operation the resuit is that the RIGHT VERT unit is always displayed at the sweep rate of the A time base unit and the LEFT VERT unit is always displayed at the sweep rate of the B time base unit independent pairs operation or sweep slaving The input conditions which provide a Hi output level so that the RIGHT VERT unit can be displayed at the A sweep rate are Pin 4 Horizontal Slave Enable HI HORIZONTAL MODE switch set to ALT or CHOP with sweep Pin 7 Hi The sweep is to be displayed Display B Command LO Pin 10 LO HORIZONTAL MODE switch set to any position except or B The input conditions which provide a LO output level so that the LEFT VERT unit can be displayed at the B sweep rate are Pin 4 Horizontal Slave Enable HI HORIZONTAL MODE switch set to ALT or CHOP with nondelayed sweep Pin 7 LO The B sweep is to be displayed Display B Command Pin 10 LO HORIZONTAL MODE switch set to any position except or B 3 ALT OR CHOP MODE HORIZ DELAYED If the A time b
293. TC T0 07716 CEAD 13701F Al5AIR2257 321 0251 00 8030000 RES FILM 4 02K 1 0 1259 TC TO 19701 5033 04 020 1 1 2258 315 0203 00 8030000 RES FILM 20K 5 0 25 57668 NTR25J E 20K A15AIR2259 313 0303 00 8030000 RES FILM 30K OHM 54 0 166W 80009 313 0303 00 15 1 260 311 2232 00 8030000 RES VAR 2K OHM 20 0 5W LINEAR 1 1450 GFOSUT 2K 15 182261 315 0272 00 010100 8029999 RES FXD FILM 2 7K OHM 525 0 25W 57668 NTR25J EO2K7 15 182262 315 0102 00 010100 029999 RES FILM 1K OHM 5 0 25W 57668 2 2 01 0 1 5 182263 307 0696 00 8 030000 RES NTWK FXD FI 7 10K OHM 2 0 15W EACH 01121 1084103 15 1 2264 321 0318 00 8030000 RES FILM 20 0K OHM 1 0 125W TC TO 19701 5033 020 A15A1R2265 315 0512 00 010100 B029999 RES FILM 5 1K OHM 55 0 25W 57668 NTR2BJ EOSK1 15 182265 321 0259 00 8030000 RES FXD FILM 4 87K OFM 125 0 1254 TC TO 07716 48700 A15A1R2266 315 0912 00 8010100 8029999 RES FILM 9 1K 5 0 25 57668 NTR25J EO9K1 AL5A1R2266 321 0430 00 8 030000 RES FILM 294K OHM 125 0 1254 TC TO 07716 CEAD2S402F AL5A1R2267 321 0399 00 8030000 RES FXD FILM 140K OHM 125 0 1254 TC T0 07716 CEAD14002F 1 1 2268 321 0297 00 8010100 029999 RES FXD FILM 12 1K OHM 1 0 125W TC TO 07716 12101 1 1 2268 321 0294 00 8021190 8029999 RES FILM
294. Table 1 3 Electrical Characteristics DISPLAY 1 3 Electrical Characteristics DISPLAY Tabie 1 2 Power Cord and Plug identification Information Performance Check information Horizontal System performance requirements Horizontal delay description A and B HORIZ signal Delay compensation network circuit description Performance Check procedure Adjustment and Performance Check procedure EMI and light filter description Warning against personal injury Crt mesh filter cleaning instructions Graticule area display specifications phosphor type and writing speed Graticule area display specifications phosphor type and writing speed Graticule area display specifications phosphor type and writing speed Plug configurations usage and reference standards REV JUN 1984 instrument Option Manual Section TABLE 6 1 CONT Option Information Locator Location Heading Option A2 United Kingdom 240 voit power cord Option A3 Australian 240 power cord Option A4 North American 240 power cord Option A5 Switzerland 220 V 10 A power cord REV JUN 1984 1 General information 1 General information 1 General Information Generai Information Tabie 1 2 Power Cord and Plug identification information Table 1 2 Power Cord and Plug identification informa
295. Tektronix COMMITTED TO EXCELLENCE PLEASE CHECK FOR CHANGE INFORMATION AT THE REAR OF THIS MANUAL 7904A OSCILLOSCOPE WITH OPTIONS INSTRUCTION MANUAL Tektronix Inc P O Box 500 Beaverton Oregon 97077 070 4593 00 Pradiuct Groin 42 Serial Number First Printing MAY 1983 Ravised Y 1987 Copyright 1983 Tektronix Inc All rights reserved Contents of this publication may not be reproduced in any form without the written permission of Tektronix Inc Products of Tektronix Inc and its subsidiaries are covered by U S and foreign patents and or pending patents TEKTRONIX TEK SCOPE MOBILE and are registered trademarks of Tektronix Inc TELEQUIPMENT is a registered trademark of Tektronix U K Limited Printed in U S A Specification and price change privileges are reserved INSTRUMENT SERIAL NUMBERS Each instrument has a serial number on a panel insert tag or stamped on the chassis The first number or letter designates the country of manufacture The last five digits of the serial number are assigned sequentially and are unique to each instrument Those manufactured in the United States have six unique digits The country of manufacture is identified as follows B000000 Tektronix inc Beaverton Oregon USA 100000 Tektronix Guernsey Ltd Channel Islands 200000 Tektronix United Kingdom Ltd London 300000 Sony Tektronix Japan 700000 Tektronix Holland NV Heerenveen The Netherlands
296. Tektronix 7A series duai channel amplifier with 1 MQ input impedance 3 Amplifier Tektronix 7A series Used throughout procedure a TEKTRONIX 7A29 Amplifier amplifier to provide vertical input 9 TEKTRONIX 7A19 Amplifier to the 7904A under adjustment 4 Time Base Tektronix 7B series time Used throughout procedure a TEKTRONIX 7B15 Delaying two needed base to provide sweep for Time Base and 7810 Time Base the 7904A b TEKTRONIX 7B85 Delaying Time Base and 7B80 Time Base TEKTRONIX DM 501A Digital Multimeter with TM 500 series Power Module b Fluke Model 825A Differential DC Voltmeter c TEKTRONIX 7D13A Digital Multimeter and 7000 series test oscilloscope may be used if lower performance is acceptabile Range 0 to 200 V accuracy within 0 1 5 Precision DC Voltmeter DVM with test leads Check and adjust power supply voltages Check External Z Axis a TEKTRONIX FG 503 Function Operation Check Adjust Generator with TM 500 series X Y Delay Compensation Power Module 6 Low Frequency Sine Wave Generator Frequency 50 kHz amplitude 2 V b Generai Radio 1310 B Oscillator Check Vertical Channel Isolation TEKTRONIX SG 503 Leveled Sine Wave Generator and TM 500 series Power Module 7 Medium Frequency Sine Wave Generator Frequency 100 MHz output amplitude variable from 0 5 to 4 voits into 50 Q
297. Test Oscilloscope 5 73 Checks Adjustment 7904A Part Il Adjustment and Performance Check G4 ADJUST COLUMN AND ROW MATCH G5 CHECK READOUT MODES A15R2243 A15R2183 NOTE NOTE If the proceeding step was not performed first per If the proceeding step was not performed first per form step 01 then proceed form step G1 then proceed G5 SETUP CONDITIONS 7904A Controls HORIZONTAL MODE G4 SETUP CONDITIONS 7904A Controls No change in settings RE ve f 9 5 Amplitier 6 A o 3 2 Test Equipment Controls Time Base Sweep Rate Triggering Auto AC Internal 4593 548 Test Equipment Controls Amplifier Display Mode Dual trace 4593 547 J a Set the READOUT INTENSITY control for a visible display a Press and hold one of the amplifier trace identity b CHECK set the time base to several sweep rates buttons throughout its range and check that the readout char acters are displayed EXAMINE the readout dispiay for correct indication of Set the READOUT GATE EXT button to GATE IDENTIFY If the readout display is incorrect adjust ment is required ADJUST Column Match adjustment R2243 and Row Match adjustment R2183 on the A15 Readout System board for correct readout of IDENTIFY Set these adjustments to the center of the range which provides correct readout indication Release the amplifier tra
298. Three contact connector compatible with Tektronix C 50 series cameras MEM PP Aaa MM aA Bottom Pin Ground Center Pin Single sweep reset Top Pin 15 V SINGLE SWEEP RESET O R Bnc input connector on rear panel to reset single sweep function of time base units installed in and B HORIZ compartments Signal Required Closure to ground or switching from the high level 50 to 10 V sink less than 40 yA to the low level 0 5 V to 5 V sink less than 12 in less than 1 ms resets the sweep Compatibie to 15 V open collector TTL source erret n NR EE ena SINGLE SWEEP READY Bnc connector on rear panel Remote ready indicator for A HORIZ time base unit Output Signal Open when not ready 5 V at 47 source impedance when ready Output will light a No 49 bulb B SINGLE SWEEP READY Bnc connector on rear panel Remote ready indicator for B HORIZ time base unit Open when not ready 5 V at 47 source impedance when nom atout will tight a No 49 bulb Output Signal M D GRATICULE READOUT SINGLE SHOT Bnc connector on rear panel Switching to the low level 1 V to 5 V sink less than 2 mA from the high level 10 V to 15 V sink less than 0 3 mA
299. U1G040L 104M NTR25J E150K 5043 6 200 50430X30K00J 5033EDLKOOF 73M1G040L103M 73U16040L104M 70N16G100L202W ORDER BY DESCR 7 9 Replaceable Electrical Parts 7904 Component No Part No Effective Dscont Name amp Description Code Mfr Part No Tektronix A3 670 4778 01 4305342 150 0048 01 A3DS345 150 0048 01 A3DS346 150 0048 01 A3P346 131 0608 00 7 10 Serial Assembly CIRCUIT BD ASSY TRIGGER LIGHT LAMP INCAND 5V 0 7683 AGED amp SEL LAMP INCAND 5V 0 06A 2683 AGED amp SEL LAMP INCAND 5V 0 06A 683 AGED amp SEL TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL QUANTITY OF 4 Mfr 80009 58854 58854 58854 22526 570 4778 01 683AS15 6834515 683A515 48283 036 REV JUL 1987 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr nt No Part No Effective _ Dscont Name amp Descrintion Code Mfr Part M 870 4778 01 CIRCUIT BD ASSY TRIGGER LIGHT 80009 670 4778 01 405362 150 0048 01 LAMP INCAND 5V 0 064 683 AGED amp SEL 58854 683 615 A4DS365 150 0048 01 LAMP INCAND 5V 0 06A 683 AGED amp SEL 58854 683 515 A4DS366 150 0048 01 LAMP INCAND 5V 0 06A 683 AGED amp SEL 58854 683 515 A4P366 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD PL 22526 48283 036 REV JUL 1987 7 11 Replaceable Electrical Parts 7904A Tektronix Serial Assembly Mfr Component No Part No tffective _ Dscont Name amp Description Code Mfr Part No A5 6
300. U2127 U2127 Displayed LO LO LO Channel 1 Left vertical LO LO Hi Channel 2 Left Vertical LO HI LO Channel 1 Right Vertical LO HI Channel 2 Right Vertical HI LO LO Channel 1 Horizontai LO HI Channel 2 A Horizontal HI HI LO Channel 1 B Horizontal HI HI Channel 2 B Horizontal SINGLE SHOT LOCKOUT Single Shot Lockout stage allows a single readout frame 8 complete words to be displayed on the CRT after which the Readout System is locked out so further readout displays are not presented until the circuit is reset inte grated circuit U2120A and U2120B are connected to form a bistable flip flop For free run operation pin 8 of U2120C is held This activates U2120C and results in a LO output level at pin 10 enabling the Timer stage to operate in a free running manner The output of the Single Shot Lockout stage remains LO to allow U2126 to operate in the free running mode until a LO is received at pin 8 of U2120C When this occurs the output level at pin 10 of U2120C does not change immediately However the Single Shot Lockout circuit is now enabled If the Channel Counter has not completed word 8 the Read out System continues to operate in the normal manner When word 8 is completed the negative going end of frame pulse is produced at pin 5 of U2127A as the Channel Counter shifts to the code necessary to display word one This pulse is applied to pin 8 of U2120C which produces a
301. V div Vertical Mode Channel 1 Sweep Rate ms div 4593 417 a Establish a ground reference for the test oscilloscope by positioning the trace to the graticule center line Do not change the test oscilloscope Position control after setting this ground reference b Set the test oscilloscope input coupling switch to dc c CHECK that the dc level of the test oscilloscope display is within 1 division of the ground reference established in part a 5 21 Checks and Adjustment 7904A Part Performance Check C3 CHECK TRIGGER SELECTOR OPERATION i CHECK the crt for a stable display of the 1 kHz NOTE If the preceding step was not performed first perform step C1 then proceed C3 SETUP CONDITIONS 7904A Controls VERTICAL MODE HORIZONTAL MODE A TRIGGER SOURCE B TRIGGER SOURCE VERT MODE MODE Calibrator i B Time Base Coaxial Cable Signal Standardizer 2 B Test Equipment Controls Signal Standardizer Vert or Horiz Step Hesp Rep Rate A Time Base Sweep 0 2 ms div Triggering Auto AC internal Magnifier B Time Base Sweep Male E rk 0 2 ms div Triggering Auto AC Internal Magnifier Independent 4593 418 Set the A INTENSITY control for a visible display Set the amplifier for a 2 division display in the upper half of the graticule area Use the time base Triggering Level control
302. W SI 30V 150MA 30V D0 35 03508 042527 144152 AL5AICR2157 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 2507 184152 1 1 2160 152 0141 02 030000 SEMICOND DVC DI 5W S1 30V 150MA 30V DO 35 03508 DA2527 1N4152 A15AICR2161 152 0141 02 030000 SEMICOND DVC DI SW S1 30V 150MA 30V DO 35 03508 DA2527 1N4152 15 1 2162 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 0 2527 1N4152 15 1 82163 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 2527 184152 A15AICR2166 152 0141 02 SEMICOND DVC D1 9W SI 30V 150MA 30V DO 35 03508 DA2527 184152 A15A1CR2167 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 1N4152 AL5A1CR2170 152 0141 02 SEMICOND DVC DI SW ST 30V 150 30V 00 35 03508 2527 1N4152 AlSAICR2171 152 0141 02 SEMICOND DVC D1 9W 51 30V 150MA 30V DO 35 03508 2507 1N4152 A15A1CR2174 152 0141 02 SEMICOND DVC D1 5V 51 30V 150MA 30V 00 35 03508 DA2527 1N4152 A15A1CR2175 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 DA2527 184152 A15A1CR2187 152 0141 02 8030000 SEMICOND DVC DI SW S1 30V 150MA 30V D0 35 03508 042527 1N4152 15 1 82192 152 0141 02 010100 029999 SEMICOND DVC D1 54 S1 30V 150MA 30V 00 35 03508 2527 1N4152 Al15A1CR2193 152 0141 02 8010100 8029999 SEMICOND DVC D1 SW S1 30V 150MA 30V 00 35 03508 DA2527 1 4152 A15A1CR2196 152 0141 02 8010100 B029999 SEMICOND DVC DI SV S1 30V 150MA 30V 00 35 03508 25
303. Y LOGIC CER DI 1UF 80 20 25V CAP CER DI 1UF 80 20 25V CAP FXD CER 01 1 80 20 25 CER DI 1UF 80 20 25V ELCTLT 100UF 50 10 10V CAP FXD MICA DI 200PF 1 500V DI 39PF 5 500V CAP FXD CER 01 1UF 80 20 25V CAP FXD CER DI 39PF 5 500V CER DI 68PF 105 500V CAP CER DI 470PF 55 500V CER 01 33 10 500 CAP 01 33 10 500 DI 470PF 5 500V CAP FXD MICA DI 130PF 1 100V CER DI 39PF 5 500V CAP FXD CER DI 39PF 5 500V CER DI 0 01UF 80 20 150V CAP FXD CER DE 170PF 5 500V CAP FXD CER 01 170PF 5 500V CAP CER 01 0 2026 50V FXD CER DI 480 207 25V CAP FXD DI 0 001UF 100 075 500V CAP FXD DI 1UF 80 20 25V 1 100 5 200 SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND OVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND OVC DI SEMICOND DVC DI SEMICOND DVC DI SEMICOND DVC DI
304. Y BARR SI 15V D0 35 50434 5082 0672 1 81918 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 1N4152 1 81922 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 2527 184152 1 1923 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 2527 144152 AiCR1927 152 0141 02 SEMICOND DVC DI SW S1 30V 150MA 30V 00 35 03508 DA2527 184152 1 1928 152 0141 02 SEMICOND DVC DI SW SI 30V 150M4 30V D0 35 03508 2527 184152 1 81929 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V D0 35 03508 0 2527 184152 1 1946 152 0141 02 SEMICOND DVC D1 5W 51 30V 150MA 30V D0 35 03508 042527 104152 1 1947 152 0141 02 SEMICOND DVC DI 5W S1 30V 150MA 30V DO 35 03508 2527 184152 1 lt 81948 152 0141 02 SEMICOND DVC DI SW SI 30V 150MA 30V DO 35 03508 DA2527 1N4152 1 81963 152 0141 02 SEMICOND DVC D1 9W S1 30V 150MA 30V DO 35 03508 DA2527 1N4152 ALJ1917 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80008 131 1003 00 1 1924 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 191943 131 1003 00 CONN RCPT ELEC CKT BD MT 3 PRONG 80009 131 1003 00 121992 131 1003 00 CONN RCPT ELEC CKT 8D MT 3 PRONG 80009 131 1003 00 111995 108 0245 00 CHOKE RF FIXED 3 9UH 76493 86310 1 111997 108 0245 00 CHOKE FIXED 3 9UH 76493 85310 1 1 1900 131 0589 00 TERMINAL PIN 0 46 L X 0 025 SQ PH BRZ 22506 48283 029 QUANTITY OF 8 1 1904 131 0608 00 TERMINAL PIN 0 365 L X 0 025 BRZ GLD P
305. Z time base units For most applications these switches can be left in the VERT MODE position This position is the most convenient since the internal trigger signal is automatically switched as the VERTICAL MODE switch is changed or as the display is electronically switched between the LEFT VERT and RIGHT VERT plug ins in the ALT VERTICAL MODE switch position It also provides a usable trigger signal in the ADD position of the VERTICAL MODE switch since the internal trigger signal in these modes is the algebraic sum of the signals applied to the vertical plug in units In the CHOP position the left vertical plug in is the trigger source Therefore the VERT MODE position ensures that the time base units receive a trigger signal regardless of the VERTICAL MODE switch setting without the need to change the trigger source selection The A and B TRIGGER SOURCE switches are illuminated to indicate the source of the trigger signal If correct triggering for the desired display is not obtained in the VERT MODE position the trigger source for either the A HORIZ or B HOHIZ time base unit can be changed to obtain the trigger signal from either the LEFT VERT or RIGHT VERT plug in The internal trigger signal is obtained from the selected vertical compartment whether the plug in in that compartment is selected for display on the crt or not the internal trigger signal is obtained from one of the vertical units but the other vertical unit is selected
306. ace is produced by the left amplifier unit and the bottom trace is produced by the right amplifier unit the sweep for both traces is produced by the A time base unit Set the sweep rate of the A time base unit to 50 milliseconds division notice the display alternates between the left and right amplifier plug in units after each sweep Turn the A time base sweep rate switch throughout its range notice that the display alternates between amplifier units at all sweep rates Set the VERTICAL MODE switch to CHOP Turn the A time base unit sweep rate switch throughout its range dual trace display will be presented at sweep rates and both amplifier units are displayed 21 by the A time base unit on a time sharing basis Set the A time base unit sweep rate switch to 0 5 milliseconds division Set the VERTICAL MODE switch to ADD The display should be four divisions in amplitude Notice that the position control of either amplifier unit moves the display Set the VERTICAL MODE switch to LEFT HORIZONTAL DEFLECTION SYSTEM 22 23 24 25 26 27 Position the start of the trace to the left graticule line with the A time base unit Position control Notice that only the A time base unit Position control affects the horizontal position of the displayed trace not the Position control of the B time base unit Set the HORIZONTAL MODE switch to B Notice that only the B time base unit Position control affects the
307. ack voltage produced by the four field windings This voltage is applied to the base of Q10 through resistive divider network R24 R25 and R11 The voltage developed by this circuit is proportional to the motor speed the motor speed starts to increase the current drive to the base of Q10 will decrease reducing the current to the motor thus maintaining a constant motor speed FAN CIRCUIT SN B040000 amp Up Current for fan B20 is provided by the 15 supply through P90 on Low Voltage Regulator board A22 The fan s 12 volt operating level is achieved by dropping ap proximately 3 volts across R20 GRATICULE LIGHT SUPPLY The Graticule Light Supply provides power to illuminate the graticule lights The front panel ILLUM potentiometer controls the output of this supply to set the brightness of the graticule lights Transistors Q144 Q148 and diode CR148 form a voltage following current buffer The output voltage at the collector of Q148 follows the voltage set at the base of 0144 by the divider made up of R142 R141 R143 and the front panel GRAT ILLUM contro on diagram 7 Resistor R148 limits the output current from this supply to protect Q148 from damage due to a short circuit REV JAN 1987 Section 4 7904 MAINTENANCE This section of the manual contains information for performing preventive maintenance troubleshooting and corrective maintenance for the 7904A Oscilloscope mainframe PREVENTIVE MAINTENANCE
308. actory operation is substantiated at the factory Checks and Adjustment 7904A TABLE 5 2 CONT Performance Check Summary Part 1 Part 11 Characteristics Performance Check Adjustment ao equirements Procedure Title erformance Procedure Title CONTROL ILLUMINATION High medium and off Three Checked in Operators Checkout Procedure in Section 2 position switch located on rear panel of power supply CAMERA POWER Three contact connector Does not normally require customer verification compatible with Tektronix Satisfactory operation is substantiated at the factory C 50 series cameras Bottom Pin Ground Center Pin Single sweep reset Top Pin 15 V SINGLE SWEEP RESET Bnc input connector on rear panel to reset singie sweep function of time base units installed in A and B HORIZ compartments Signal Required Closure to ground or switching from the high ievel 50 to 10 V sink less than 40 pA to the low ievel 0 5 V to 5 V sink less than 12 mA in less than 1 ms resets the sweep Compatible to 15 V open collector source A SINGLE SWEEP READY Bnc connector on rear panel Remote ready indicator for A HORIZ time base unit Output Signai Open when not ready 5 V at 47 source impedance when ready Output will light a No 49 bulb B SINGLE SWEEP READY Bnc connector on rear panel Remote ready indicator for B HORIZ time base unit Output Signal Open
309. age is the Zeros Logic and Memory During time slot 1 TS 1 this stage checks if zero adding or prefix shifting information has been encoded by the plug in unit and stores it in the memory until time 3 39 Theory of Operation 7904A 1 jo uoisuedxe eunjn suoneoo pesnuf sseippe jeuonguedOo m t n tr Aejdsip ui ooeds e x 20 Character selection matrix for 7904 Readout System SN 031767 amp Above LO OU uone2oj uoneoo uod jeuroeg jwg x5 yanng JequnN 9800 jeuuoop ixeH woj Figure 3 REV NOV 1985 3 40 slots 5 6 or 8 After storing this information it triggers the Display Skip Generator stage so that there is no display during time slot 1 as defined by Standard Readout Format see Table 3 11 When time siots 5 6 and 8 occur the memory is addressed and any information stored there dur ing time siot 1 is transferred to the input of the Column De coder stage to modify the analog data during the applicable time slot Another operation of the Zeros Logic and Memory stage is to produce the identify function When time siot 1 is en
310. agrams and Circuit Board Illustrations Use care when checking voltages and waveforms around the integrated circuits so that adjacent leads are not shorted together A convenient means of clipping a test probe to the in line multi pin integrated circuits is with an integrated circuit test clip This device also doubles as an integrated circuit extraction tool Diodes A diode can be checked for an open or shorted condition by measuring the resistance between terminals with an ohmmeter on a scale having a low internal source current such as the 1k scale The resistance should be very high in one direction and very low when the meter leads are reversed When checking diodes do not use an ohmmeter scale that has a high internal current since high currents may damage the diodes under test Resistors Check the resistors with an ohmmeter Resistor tolerances are given in Section 7 Replaceable Electrical Parts Normally resistors do not need to be replaced unless the measured value varies widely from the specified value Capacitors A leaky or shorted capacitor can best be detected by checking resistance with an ohmmeter on the highest scale Do not exceed the voltage rating of the capacitor The resistance reading should be high after initial charge of the capacitor An open capacitor can best be detected with a capacitance meter or by checking whether the capacitor passes ac signals 8 REPAIR AND ADJUST THE CIRCUIT if
311. aitered if the exact item of equipment given as an example in Table 5 3 is not available first check the Minimum Specifications column carefully to see if any other equipment might suffice Then check the Purpose column to see where this item is used If used for a performance check or adjustment that is of little or no importance for your measurement requirements the item and corresponding step s can be deleted TABLE 5 3 Test Equipment 1 Test Oscilloscope with 10X probes Bandwidth dc to 100 MHz deflection factor 50 mV to 10 V division at probe tip inputs two 1 capable of inverting one i input for operation as differential amplifier sweep rates 1 ms to 0 1 us division Used throughout Checks and Adjustment procedures Examples of Applicable Test Equipment a TEKTRONIX 7803 Oscilloscope with 7 26 Dual Trace Amplifier 7 80 Time Base and P6063B Switchable Attenuation Probes b TEKTRONIX 2445 150 MHz Oscilloscope with P6131 Probe c Refer to Tektronix Products catalog for compatible equipment REV NOV 1985 5 11 Checks and Adjustment 7904A TABLE 5 3 CONT Test Equipment Examples of Applicable Test Equipment Minimum Specifications Description Used to check and adjust readout system Any Tektronix dual channel amplifier may use the one from the test oscilloscope aar a a YET ES a
312. ajous display with separation of 0 28 division or less indicates 2 or less phase shift see Figure 5 1 Remove the amplifier unit from the A HORIZ compartment and install it in the B HORIZ compartment leave signal connected Set the HORIZONTAL MODE to B Repeat part b of this step Checks and Adjustment 7904A Part 1 Check Figure 5 1 Typical display when checking X Y phase compensation 5 25 Checks and Adjustment 7904A Part Performance Check E VERTICAL SYSTEM TR e eire ANPP aaeeea e TEES P Us Af e TTA AERE SP TT Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 3 Amplifier 10 Signal Standardizer 4 Time Base two required 13 Coaxial Cable 7 Medium Frequency Sine Wave Generator 14 Attenuator 2X E1 VERTICAL SYSTEM PRELIMINARY E2 CHECK VERTICAL AMPLIFIER GAIN SETUP NOTE a Perform the Performance Check Power Up First perform step E1 then proceed Sequence E2 SETUP CONDITIONS b Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for 7904 Controls No change n settings any modifications which may affect this procedure C Set the 7904A controls as follows POWER 5 On VERTICAL MODE RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE
313. an approximate 2 volt peak to peak 1 kilohertz sine wave signal to the left vertical amplifier unit input with a coaxial cable and bnc T connector Set the A HORIZ time base unit sweep rate to display 5 cycles of sine wave signal and set the amplifier unit deflection factor to 0 5 volts division four division display Now connect a coaxial cable from the T connector at the amplifier unit input to the rear panel Z AXIS INPUT connector Rotate the A INTENSITY control until intensity modulation is visible on the display The positive peaks of the waveform should be blanked out and the negative peaks intensified Notice that the setting of the intensity controls determines the amount of intensity modulation that is visible Disconnect all the cables DETAILED OPERATING INFORMATION GRATICULE The graticule matrix is scribed on the inside of the crt faceplate providing accurate parallax free measurements The graticule is divided into eight vertical and ten horizontal divisions Each division is one centimeter square divided into five minor divisions along each axis Options are available for 0 5 centimeter square divisions see Instrument Options section The vertical gain and horizontal timing of the plug in units are calibrated to the graticule so that accurate measurements can be made from the crt The illumination of the graticule lines can be varied with the GRAT ILLUM control Figure 2 3 shows the graticule and defines the v
314. arious measurement lines The terminology defined here will be used in all discussions involving measurements from 2 8 the graticule The markings 0 10 90 and 100 on the left side of the graticule are for accurate rise time measurements GRATICULE ILLUMINATION The GRAT ILLUM contro varies the illumination of the graticule lines The GRAT ILLUM can also be operated in the PULSED mode With the ILLUM control set to the PULSED detent position and the GATE EXT switch set to GATE pushbutton in the graticule will be illuminated momentarily after the GATE occurs The GATE switch selects whether A time base gate or B time base gate triggers the graticule illumination With the GRAT ILLUM GATE EXT switch set to EXT the momentary graticule iliumination can be actuated by applying a remote signal to the GRATICULE READOUT SINGLE SHOT connector see Table 1 8 in section 1 for specifications When operating in the PULSED mode the level of illumination is controHed by the GRAT ILLUM PRESET screwdriver adjustment LIGHT FILTER The tinted face plate filter minimizes light reflections from the face of the crt to improve contrast when viewing the display under high ambient light conditions This filter should be removed for waveform photographs or for viewing high writing rate displays To remove the filter pull outward on the bottom of the plastic crt mask and remove it from the crt bezel Remov
315. as a reference wave shape when checking or adjusting the compensation of high resistance probes The square wave output from the CALIBRATOR has a flat top any distortion in the displayed waveform is due to the probe compensation SIGNAL OUTPUTS Sawiooth Out The SAWTOOTH connector provides a positive going sawtooth signal derived from tne time base unit installed in the A HORIZ compartment or from the time base unit installed in the B HORIZ compartment The front panel A or B SAWTOOTH switch determines whether the HORIZ or the B HORIZ compartment is the source of the SAWTOOTH output signal The unit of time for the sawtooth output is determined by the setting of the time base unit Time Division switch Refer to Table 1 3 in the General information section for signal parameters Gate Out The GATE connector provides a positive going rectangular pulse which is derived from a time base unit installed in either horizontal plug in compartment The A or B GATE switch selects the source of the GATE signal from the time base unit installed in the A HORIZ compartment or the B HORIZ compartment The 2 14 duration of the GATE signal is the same as the duration of the respective unmagnified sweep The amplitude of the GATE signal is about 0 5 volt into 50 ohms about 10 volts into 1 megohm Signal Out The SIG OUT connector provides a sample of the vertical deflection signal The source of the output sig
316. ase unit is set to the delayed mode when the HORIZONTAL MODE switch is set to either ALT or CHOP the operation of the stage is changed from that discussed above Now the Vertical Alternate Command switches between the HI and LO states at a rate that is one half the repetition rate of the Display B Command The resultant crt display in the ALT position of the VERTICAL MODE switch allows the RIGHT VERT unit to be displayed first against the A sweep delaying and then against the B sweep delayed Then the display switches to the LEFT VERT unit and is displayed 3 13 Theory of Operation 7904A TABLE 3 8 Input Output Combinations for the Vertical Binary Stage Has no effect in this case e e s Te OUTPUT DELAYED MODE DISPLAY LEFT SWEEP SLAVING ALT OR CHOP DELAYED MODE ALT CHOP NON 1 Hf output is LO prior to LO it goes and vice versa Actuated by negative going edge Repetition rate one half alternate pulse rate Repetition rate one half display B rate consecutively against the A and B sweeps in the same manner The input conditions for this mode of operation are Pin 4 Horizontal Slave Enable LO The A time base unit set for delayed operation Pin 8 Hi or LO Vertical Alternate Command changes state at to LO transition of Display Command Pin 10 LO HORIZONTAL MODE switch set to any position except A or B Table 3 8 shows the input output com
317. ass through the optional X Y delay compensation network Option 2 instruments only The Horizontal Channel Switch receives an X Y inhibit signal from the Readout system to provide the time sharing between the vertical and readout signals The selected horizonta signal is amplified by the Horizontal Amplifier circuit to provide horizontal deflection of the crt The Horizontal Amplifier circuit accepts an input signal from the Readout System to produce the horizontal portion of the aipha numeric readout display The Readout System provides an alpha numeric display of information encoded by the plug in unit s The readout display is written on the crt on a time shared basis with the analog waveform display The VERTICAL and HORIZONTAL MODE switch circuits determine which plug in unit s displays readout information The Readout system sends inhibit commands to the Vertical Channel Switch Vertical Amplifier Horizontal Channel Switch Horizontal Amplifier Focus Amplifier and Z Axis logic circuits Signals from the Readout System produce the alpha numeric display for the Vertical Horizontal and Z Axis Amplifier circuits The Logic circuit develops control signals for use in other circuits within the instrument and the plug in units These contro signals automatically determine the correct instrument operation relation to the plug in units plug in unit control settings and 7904 front panel control settings The Logic circuit perfor
318. at 2 0 volts The Off pins are either at 2 5 volts or at LO level The A Trigger Channel Switch has four operating modes Left Right Alt and Add In the Left and Right modes the Add logic level is HI on pin CF the Right Logic Level on pin CG is LO for Left and is HI for Right in the ALT mode Add is and Right alternates between LO and In the ADD Mode both Add and Right are LO See the discussion on Mode Switching in this section of the Manual Zener diodes VH237 and VH247 shift the dc level downward by 9 volts to set the output of U274 near ground Diodes VR237 and VH247 are voltage matched to within 100 mV AND B TRIGGER AMPLIFIER The operation of the A and B Trigger Amplifiers is similar Therefore only a discussion of the Trigger du Amplifier is given Integrated Circuit U274 provides final amplification of the trigger signal Components R261 and 272 are bias resistors for U274 Zener diodes VR237 and VR247 have a 596 voltage tolerance therefore the dc voltage level at pins 7 and 9 of U274 is 5 8 volt within 0 45 volt The dc common mode voltage with its 0 45 volt uncertainty is picked off at pin 8 and pin 12 of U274 and applied to the noninverting input of 02528 The output of U252B is 1 2 volts more positive than the input and is used for internal biasing at pin 15 of U274 Resistor R274 determines the gain of U274 The overall voitage gain of the A trigger selector from the input co
319. at graticule center are aligned with the graticule vertical and horizontal center lines within 0 1 division d horizontal traces at the top and bottom of the graticule for 0 1 division or less of bowing or tilt 5 15 Checks and Adjustment 7904A Part i Performance Check B CALIBRATOR AND OUTPUT SIGNALS Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 1 Test Oscilloscope 11 Time Mark Generator 4 Time Base 13 Coaxial Cables four 42 inch required 5 Precision DC Voitmeter DVM 15 Adapter bnc T Bi CALIBRATOR AND OUTPUT SIGNALS B2 CHECK CALIBRATOR OUTPUT VOLTAGE PRELIMINARY SETUP NOTE a Perform the Performance Check Power Up First perform step B1 then proceed Sequence Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure B2 SETUP CONDITIONS 7904A Controls No change in settings C Set the 7904A controls as follows POWER 5 On VERTICAL RIGHT VERT TRACE SEPARATION 8 Midrange A TRIGGER SOURCE VERT MODE Precision A INTENSITY Fully counterclockwise HORIZONTAL MODE A B Fully counterclockwise B TRIGGER SOURCE VERT MODE READOUT INTENSITY OFF in detent GRAT
320. ations from the standard symbology or devices not defined by the standard are described in the circuit description for the applicable device NOTE Logic Symbols used on the diagrams depict the logic function as used in this instrument and may differ trom the manufacturer s data these commonly used circuits refer to available textbooks LOGIC POLARITY All logic functions are described using the positive logic convention Positive logic is a system of notation where the more positive of two levels is called the true or 1 state the more negative level LO is called the false or O state The HI LO method of notation is used in this logic description The specific voltages that constitute a or LO state vary between individual devices Whenever possible the input and output lines are named to indicate function that they perform when at the Hi true state INPUT OUTPUT TABLES Input Output truth tables show the input combinations important to a particular function along with the resultant output conditions This table may be given either for an individual device or for a complete logic stage Examples of input output tables for individual dev ces can be seen in Table 3 1 NON DIGITAL DEVICES Not all of the integrated circuit devices in this instrument are digital logic devices The function of non digital devices is described individually using operating waveforms or other techniques to illustrate
321. ators are not activated Time slot pulses 1 2 and 3 are also connected to pin 4 of U2260 through VR2262 VR2263 VR2264 respectively and to R2262 and R2265 This configuration adds a space to the displayed word during time slots 1 2 and 3 even if information is not encoded for display DECIMAL POINT LOCATION ENCODED DURING THIS TIME SLOT NO DISPLAY during these time slots With this feature the information displayed during time slot 4 scaling data always starts in the fourth character position whether data has been displayed in the previous time slots or not Therefore the resultant crt display does not shift position as normal invert or cal uncal information is encoded The Word Trigger pulse connected to pin 8 resets the Character Position Counter to the first character position at the end of each word The Decimal Point Logic portion of this stage allows decimal points to be added to the crt display With the Standard Readout Format row 7 encoded coincident with columns 3 through 7 addresses a decimal at one of the five locations identified in row 7 of the Character Selection Matrix Fig 3 9 This instruction refers to the decimal point location in relation to the total number of characters possible in one word see Fig 3 18 For exampie coiumn 3 encoded with row 7 during time slot 1 places a decimal point in location number 3 As shown in Figure 3 18 this displays a decimal point after the third character tha
322. base unit main gate B B Gate derived from B HORIZ time base unit main gate Polarity Positive going with baseline at 0 V within 1 0 V into 1 Output Voltage Into 500 0 5 V within 10 into 1 MO 10 V within 10 up to 1 us div sweep rate S RR ERXX A O M AME GATE cont Rise Time into 500 Fall Time into 500 SIG OUT Source Output Voltage into 50 0 General information 7904A TABLE 1 3 CONT Electrical Characteristics Characteristics Performance Requirements SIGNAL OUTPUTS CONT 5 ns or less 15 ns or less Selected by B TRIGGER SOURCE switch Same as B TRIGGER SOURCE 25 mV div of vert cal deflection within 2596 into 1 Bandwidth into 500 DC Centering Readout Modes Free Run Not Labeled on Front Panel PULSED Pulsed Source Graticule Type Area Standard Instrument and Option 78 Option 4 Option 13 Phosphor Standard Option 4 Beamfinder Geometry MAN Manual trigger independent of other pulse sources 0 5V div of vertical defection within 25 maximum output 2 V Varies with vertical plug in selected See 7904A Oscilloscope Vertical System Specification in Table 1 7 0 V within 1 V into 1 READOUT DISPLAY Internal switch on Readout Board must be in Free Run position Continuously displayed READOUT contro not in PULS
323. binations for the Vertical Binary stage PLUG IN BINARY The Plug in Binary stage produces the Plug in Alternate Command to alternate dual trace units The Plug in Binary stage U4412 uses the same type of integrated circuit as the Horizontal Binary and Vertical Binary stages When the Plug In Alternate Command level is and the plug in unit is set for alternate operation Channel 2 of the dual trace unit is displayed When it is LO Channel 1 is displayed The repetition rate of the Plug In Alternate Command is determined by the setting of the VERTICAL MODE switch For positions of the VERTICAL MODE switch except ALT the Plug in Alternate Command is the same as the VERT 3 14 ALTERNATE Command at pin 6 of U4368 Vertical Binary stage Since Vertical Alternate Command is derived directly from the Display B Command this allows the two channels of a dual trace vertical unit to be slaved to the time base units nondelayed dual sweep horizontal modes only in the same manner as previously described for independent pairs operation between the vertical and time base units The resuitant crt presentation when the dual trace unit is set for alternate operation displays the Channel 1 trace at the sweep rate of the B time base unit and the Channel 2 trace at the sweep rate of the A time base unit The Plug In Alternate Command switches from HI to LO as the Display B Command from the Horizontal Binary stage switches from LO to HI
324. ce identify button pressed in and set the READOUT INTENSITY control to PULSED Set the GATE mode switch to A Set the READOUT PRESET control for a visible read out display Set the time base unit for a free running not triggered sweep at a rate of 0 2 second division CHECK that the readout characters are blanked out while the sweep is running and are displayed immedi ately after the end of the sweep each character en coded by the plug in units is displayed only once for each sweep Set the READOUT GATE EXT button to EXT released CHECK press the READOUT MAN pushbutton and notice that one frame of readout is displayed Turn POWER switch OFF Replace the fan blade re moved at start of procedure and the side covers This completes the Part II Adjustment and Performance Check Procedure 5 74 ADD NOV 1985 Section 6 7904 INSTRUMENT OPTIONS Your 7904A Oscilloscope may be equipped with one or more instrument options A brief description of each available option is given in the following discussion Option information is incorporated into the appropriate sections of the manual Refer to Table 6 1 and the Table of Contents for location of option information For further information on instrument options see your Tektronix Products catalog or contact your Tektronix Field Office WARNING To avoid electric shock hazard operating personnel must not remove the protective instrument covers Componen
325. ces between the left and right Output Amplifiers due to the different polarity of the transistor pairs e Z AXIS AND FOCUS AMPLIFIER A schematic diagram of the Z Axis and Focus Amplifier is given on diagram 12 in Section 8 of this manual Diagrams and Circuit Board Illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use the stage names to further identify portions of the circuitry on diagram 12 Z AXIS AMPLIFIER The Z Axis Amplifier provides the drive signal to control the crt intensity level through the control grid DC Restorer stage of the High Voltage circuit diagram 13 The Z Axis Amplifier receives two input signals the Z Axis signal which controls the trace intensity and the Z Readout signal which controls the readout intensity Both signals are fed through common base amplifier Q113 to establish low input impedance Transistors Q122 and Q132 comprise a single ended paraphase amplifier that along with Output level adjustment R135 and Z Axis Amplifier Gain adjustment R125 controls the operating current of this input stage The signal from the output of Q122 is inverted by Q127 and applied to the base of emitter follower Q143 where it is dc coupled to the bases of Q167 Q166 through resistor R166 of the output stage The output stage is comprised of three networks a p
326. ch may affect this procedure c See the B foldout page in Section 8 Diagrams and Circuit Board lHustrations d Set the 7904A controis as follows POWER Lb Vor A Re On pushbutton in VERTICAL LEFT VERT TRACE SEPARATION Midrange A TRIGGER SOURCE VERT MODE A INTENSITY naaa Fully counterclockwise HORIZONTAL MODE A B 1 Fully counterclockwise B TRIGGER SOURCE VERT MODE FOCUS VR E vA La CS PR Midrange READOUT eei OFF in detent GRAT ILLUM Midrange CONTROL ILLUMINATION MEDIUM rear panel WARNING Extreme care must be used when making the following adjustments because dangerous potentials are present 5 38 Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 13 15 16 17 19 Coaxial Cable two 42 inch required Adapter BNC T Screwdriver Phillips Screwdriver Slotted Tool Alignment B2 ADJUST HV A20R115 NOTE First perform step 1 then proceed 2 SETUP CONDITIONS 7904 Controls No change in the settings Precision DC Volimeter DVM Test Leads Test Equipment Controls Precision DC Voltmeter DVM Appropriate range for voltage to be measured 4593 503 Temporarily set the POWER switch to OFF and remove the 20 High Voltage Board shield secured by three
327. ch stage is made up primarily of integrated circuit 0668 Inputs 7 and 9 provide a differential input for the signal from the right vertical plug in unit Input pins 17 and 19 provide a differential input for the signal from the left vertical plug in unit The differential output signal at pins 3 and 13 is connected to J694 and 592 respectively Components U682 0682 Q676 and Q672 supply standing current to U668 and maintain the output common mode dc level at 8 5 voits for ail Channel Switch modes The common mode level at pins 3 and 13 of U668 is sensed by R559 R659 and compared with a reference level determined by divider R680 R681 Assume for example that pin 2 of U682 is lower than pin 3 indicating an output level below 8 5 volts The output of U682 at pin 6 will be driven positive and current will flow in R683 This current must be supplied from the 15 V supply via R682 thereby lowering the base voltage of Q682 This increases the collector current in Q682 Transistor Q676 operates as a common base amplifier and passes along the increased collector current to pin 3a of U668 This increases the output common mode level thus bringing U682 into balance The voltage at pin 3a of U668 depends on the Channel Switch mode in LEFT RIGHT ALT or CHOP pin 3a is at 10 5V in ADD it is 12 5 V when X Y Inhibit is pin is 8 5 volts all modes the current supplied by 676 is 160 milliamperes plus or minus small variations requi
328. ches S801 and 5811 to the out down position 4593 534 a Set the low frequency sine wave generator for eight divisions of vertical and horizontal deflection at 35 kHz Set the Amplifier unit controls to match the vertical and horizontal defiection b CHECK crt display for a Lissajous display with Separation of 0 28 division or less indicates 2 or less phase shift see Figure 5 3 c Remove the amplifier unit from the A HORIZ compartment and install it in the HORIZ compartment leave signal connected Set the HORIZONTAL MODE to B d Repeat part b of this step NOTE Option 2 adds an X Y Compensation network to equalize the signal delay between the Figure 5 3 Typical display when checking X Y phase vertical and horizontal deflection systems 17 compensation the instrument under test does not contain Option 2 omit the remainder of this step 5 60 Checks and 7904 Part and Performance Check F VERTICAL SYSTEM Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment Amplifier Time Base two required Medium Frequency Sine Wave Generator On Pw High Frequency Sine Wave Generator 10 Signal Standardizer 13 14 17 18 19 Coaxial Cable Attenuator 2X Screwdriver Slotted Tool Alignment Nylon Tool Alignment F1 VERTICAL SYSTEM PRELIMINARY SETUP a Perform the Adjustment and P
329. cial or matched characteristics and to calculate gain leakage breakdown voltage etc Spectrum Analyzer Plug in Units The 7000 series spectrum analyzer plug in units display signal amplitudes dispersed over portions of the rf spectrum Absolute signal energy is plotted on the vertical axis against frequency on the horizontal axis Applications include waveform and distortion analysis electromagnetic interference and random noise measurements filter design spectrum surveillance etc X Y OPERATION some applications it is desirable to display one signal versus another X Y rather than against time interval sweep The flexibility of the amplifier plug in units available for use with the 7904A provide the means of applying external signals to the horizontai deflection system The 7904A is shipped from the factory to provide X Y operation one amplifier unit in a vertical compartment and one amplifier unit in a horizontal compartment with Z Axis control provided by a time base unit installed in the remaining horizontal compartment see Fig 2 5 When an amplifier is installed in a horizontal plug in compartment the contro of the Z Axis is switched to the remaining horizontal compartment in which the time base unit is installed as is indicated by the A or B intensity control indicator lights This is independent of the horizontal mode switch setting The time base unit wil control the Z Axis and should be triggered internal
330. cilloscope sweep rate to 10 ns division EXAMINE the pulse rise time for 9 to 15 nanoseconds measured between the 10 and 90 amplitude points of the pulse INTERACTION the adjustments in parts e and affect the pulse rise time If rise time is not within the stated limits repeat parts e through Disconnect the probe Checks and Adjustment 7904A Part ii Adiustment and Performance Check B5 ADJUST FOCUS LEVEL A21R70 NOTE If the preceding step was not performed first perform step B1 then proceed B5 SETUP CONDITIONS 7904A Controls INTENSITY HORIZONTAL MODE Precision DC Voltmeter DVM Li amp 1 Test Equipment Controls Time Base Sweep Rate Triggering Auto AC External Precision DC Voitmeter 200 volts or greater 4993 506 a Connect the precision dc voltmeter set to measure 200 volts between TP83 located on the A21 Z Axis Board and chassis ground The B INTENSITY control must be in the counterclockwise position b EXAMINE the voltmeter for a reading of 120 to 126 volts c ADJUST Focus Output Level adjustment R70 located on the A21 Z Axis Board for a voltmeter reading of 123 volts d Remove the DVM test leads 5 41 Checks and Adjustment 7904A Part li Adjustment and Performance Check B6 ADJUST B CONTRAST A2R2015 NOTE If the preceding step was not performed first perform step B1 then proceed B6 SETUP CO
331. circuit etc or passive switch or relay Refer to Table 1 3 in the General Information section for specific parameters on each input Remote Single Sweep Reset An external single sweep reset signal can be applied to time base units installed in the horizontal plug in Operating instructions 7904A compartments through the rear panei SINGLE SWEEP RESET input connector This remote reset function is a duplication of the manually operated single sweep reset function pushbutton located on the front panel of the 7B series time base units A and SINGLE SWEEP READY outputs are provided for external indicators The indicators signify that the time base unit has been reset and 15 ready to present a single sweep when the next trigger pulse arrives Refer to Table 1 3 in the General Information section of this manual for signal parameters Remote Graticule and Readout Single Shot The GRATICULE READOUT SINGLE SHOT bnc connector located on the rear panel allows an external signal to actuate one frame of readout information and one momentary illumination of the graticule when the READOUT INTENSITY and GRAT ILLUM controls are set to PULSED and the GATE EXT pushbuttons for READOUT and GRAT ILLUM are set to EXT Refer to Table 1 3 in the General Information section of this manual for input requirements APPLICATIONS The 7904A Oscilloscope and associated plug in units provide a flexible measurement system The capabilities of t
332. ck G READOUT SYSTEM SN B031766 amp Below Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 2 Amplifier Dual Channei 4 Time Base Gi READOUT SYSTEM PRELIMINARY SETUP a Perform the Adjustment and Performance Check Power Up Sequence b Refer to Section 6 instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure See the rt foldout page in Section 8 Diagrams Board lilustrations d Set the 7904A controls as follows POWER isto eros TER On VERTICAL MODE RIGHT VERT TRACE SEPARATION Midrange A TRIGGER SQUBOE 2 VERT MODE A 5 see ie Midrange HORIZONTAL MODE Midrange B TRIGGER SOURCE VERT MODE READOUT INTENSITY OFF in detent GRAT ILLUM Loteries ve x eei Midrange Pushbutton out Readout Selector Switch Free Run see Test Point and Adjustment Locations G REV NOV 1985 17 Screwdriver slotted 19 Tool Alignment APVAN VALOREM M QAI aaa aa G2 ADJUST READOUT VERTICAL SEPARATION CENTERING AND CHARACTER HEIGHT A15R2291 A18R737 A15R2273 A28R101 A28R114 NOTE First perform step G1 then pr
333. condition only occurs once every fifth clock pulse and only when the HORIZONTAL MODE switch is set to CHOP When both of these outputs are at their HI level the next clock pulse switches both outputs LO and at the same time switches the Horizontal Chopped Blanking to the LO level This change at time does not appear at pin 4 immediately due to a delay network in the circuit The delay is necessary to make the Horizontal Chopped Blanking coincide with the Vertical Chopped Blanking produced by U4320 and the switching between the displayed signals Compare bottom two waveforms of Fig 3 5B also see Vertical Chopped Blanking for further information After the delay time the output level at pin 4 goes LO where it remains for about 0 5 microsecond which is equal to the period of the clock pulse two megahertz repetition rate The Horizontal Chopped Blanking time must longer than the Vertical Chopped Blanking time since it takes more time for the display to switch between horizontal units than between vertical units During the time that the level at pin 4 is LO the crt is blanked and the Vertical Chopping Signal and the Plug In Chop Command cannot change levels The clock pulse at Ts changes only the Horizontal Chopped Blanking output at pin 4 After the delay time this pin goes Hi to unblank the crt For the next three clock pulses the Vertical Chopping Signal output and Plug In Chop Command operate in the normal manner
334. connector from the board 4 Remove the Fan assembly from the instrument 5 To replace the Fan assembly place the two screws through the holes in the bracket and secure the fan motor assembly 6 Replace the pin connector matching the index arrow with the arrow on the circuit board 7 Replace the screw which holds the board to the standoff mount A22 Low Voltage Regulator Circuit Board Remove and replace the A22 Low Voltage Regulator circuit board as follows 1 Slide the power supply unit out of the instrument see Power Supply Unit Removal 2 Disconnect the multi pin connectors from the board two of the multi pin connectors are self locking see the discussion on Multi Pin Connectors in this section Note the location of the pin connectors so they may be correctly replaced SCREWS SECURING THE PLUG IN INTERFACE CONNECTORS TO THE CHASSIS GROUND STRAP SECURING SCREWS 2314 32 Figure 4 12 Location of securing screws for the A6 Main Interface board 4 20 REV JAN 1987 lf the A22 Low Voltage Regulator board is to be removed to allow access to other parts of the power supply unit proceed with steps 3 and 4 only If the board is to be removed from the instrument proceed with steps 3 through 6 Remove the 2 screws located in the access holes under the A22 Low Voltage Hegulator board These screws secure the chassis Remove the 4 screws securing the Low Voltage Regulator chassi
335. cription Code Mfr Part No CIRCUIT BD ASSY MAIN HORIZONTAL AMP 80009 570 1632 05 CIRCUIT BD ASSY HORIZONTAL AMPLIFIER 80009 670 1632 06 CAP ELCTLT 1UF 50 1025 50V NPLZD 54473 5 1 DI 82PF 10 LOOV CAP FXD ELCTLT 220 50 10 25V CAP FXD CER 01 1000PF 10 100V CAP VAR CER D1 5 25PF 100V CAP VAR CER D1 5 25PF 100V DI 1000PF 10 100V FXD ELCTLT 22UF 50 10 25V FXD CER 01 470 10 100 04222 101 820 54473 ECE A25V22L 04222 101 102 59660 518 000 5 25 59660 518 000 5 25 04222 101 102 54473 ECE A25V22L 04222 101 471 CAP FXD CER 01 5 6 0 25 2000 91642 150 200NPO569C CAP FXD CER D1 470PF 10 100V CAP DI 0 01UF 107 100V D1 0 01UF 102 100V FXD DI 0 01UF 80 20 150V CAP VAR AIR DI 1 9 15 7 PF 250V MICA DI 70PF 175 100V MICA 01 77 1 100 C811 IS SELECTABLE CAP FXD MICA D1 70PF 175 100V CAP FXD MICA 01 77 1 100 C840 IS SELECTABLE VAR AIR DI 1 9 15 7 PF 250V DI 0 01UF 100 0 250V 01 0 010 1025 1007 04222 101 471 04222 201 103 04222 201 103 59821 010324075030 74970 187 0109 055 00853 D155E700F0 00853 D155E770F0
336. ct tested or replaced parts Check the electrolytic capacitors which filter the supplies including C154 under the board for shorts 4 13 7904 Corrective maintenance consists of component replacement and instrument repair Special techniques required to replace components in the 7904A Oscilloscope mainframe are given here OBTAINING REPLACEMENT PARTS Most electrical and mechanical part replacements for the 7904A can be obtained through your Tektronix Field Office or representative However many of the standard electronic components can be obtained locally in less time than is required to order them from Tektronix Inc Before purchasing or ordering replacement parts check the parts list for value tolerance rating and description NOTE When selecting replacement parts remember that the physical size and shape of a component may affect its performance in the instrument All replacement parts should be direct replacements unless you know that a different component will not adversely affect instrument performance SPECIAL PARTS Some parts are manufactured or selected by Tektronix Inc to satisfy particular requirements or are manufactured for Tektronix Inc to our specifications Most of the mechanical parts used in this instrument have been manufactured by Tektronix Inc To determine manufacturer of parts refer to Parts List Cross index Mfr
337. ct the 7904A to a suitable power source 2 Check Horizontal Gain and Low Frequency Linearity 5 22 3 Press the POWER button and allow at least 20 3 Check High Frequency Timing 5 24 minutes warmup before proceeding 4 Check X Y Delay Compensation 5 24 m ROM E VERTICAL SYSTEM CAUTION 1 Vertical System Preliminary Setup 5 26 Qc Dd CQ 2 Check Vertical Amplifier Gain 5 26 To prevent instrument damage turn off 3 Check Vertical Low Frequency 7904 POWER before installing or removing onte d En a icd SUPR E ER 5 27 plug in units 5 14 Checks and Adjustment 7904A Part 1 Check Z AXIS AND DISPLAY Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 3 Amplifier 4 Time Base 6 Low Frequency Sine Wave Generator Ai Z AXIS AND DISPLAY PRELIMINARY SETUP a Perform the Performance Check Power Up Sequence b Refer to Section 6 Instrument Options and to the Change Information at the rear of this manual for any modifications which may affect this procedure C Set the 7904A controls as follows POWER On pushbutton in VERTICAL MODE LEFT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE A INTENSIFY Fully counterclockwise HORIZONTAL MODE INTENSITY Fully counterci
338. cted sweep rate To provide correct triggering the displayed signal which provides the trigger signal must precede the second display in time Since the signals show true time relationship time difference measurements can be made from the display Algebraic Addition The ADD position of the VERTICAL MODE switch can be used 1 to display the sum or difference of two signals 2 for common mode rejection to remove an undesired signal or 3 for dc offset applying a dc voltage to one channel to offset the dc component of a signal on the other channel The isolation between the vertical plug in compartments is at least 160 1 from dc to 100 megahertz it decreases to 80 1 from 100 megahertz to 500 megahertz The overall deflection on the crt in the ADD mode is the algebraic sum of the signals from the vertical plug in units It is difficult to determine the voltage amplitude of the resultant display unless the amplitude of the signal applied to one of the plug ins is known This is particularly true when the vertical units are set to different deflection factors since it is not obvious which portion of the display results from the signal applied to a given plug in unit The polarity and repetition rate of the applied signals will also affect the ADD display The following precautions should be observed when using the ADD mode 1 Do not exceed the input voltage ratings of the plug in units 2 Do not apply large signals to the plug in
339. current flows through R2213 from Q2240 and the Zeros Logic and Memory stage The purpose of this quiescent current will be discussed in connection with the Zeros Logic and Memory stage This current biases Q2215A so that its base is about 0 2 volt more positive than the base of Q2215B in the absence of column data Therefore since Q2215A and Q2215B are connected as a comparator Q2215A will remain on unless its base is pulled more negative than the base of Q2215B The analog data output from the Column Data Switch produces a 0 5 volt approximately change for each unit of column current that has been encoded by the plug in unit Whenever any information appears at the output of the Column Data Switch the base of Q2215A is pulled more negative than the base of Q2215B resulting in negative LO Display Skip output to the Timer stage through Q2225 Recall that a LO was necessary at the skip input of the Timer so it couid perform the complete sequence necessary to display a character Transistors Q2223 and Q2229 also provide Display Skip action The end of word level connected to their emitters is LO only during time siot 1 This means they are enabled only during this time slot These transistors allow the Zeros Logic and Memory stage to generate a Display Skip signal during time slot 1 when information that is not to be displayed on the crt has been stored in memory further information is given under Zeros Logic and Memory COLUMN A
340. current during time slot 1 Referring to the Character Selection Matrix Figure 3 9 two units of column current along with the two units of row current encoded by resistor R10 row 3 indicates that two zeros shouid be added to the display Resistor R120 adds one unit of column current during time slot 2 and along with the one unit of current from the row output the Readout System is instructed to add an invert arrow to the display Resistor R130 is not connected to the time slot 3 line since the deflection factor is calibrated Therefore there is no display on the crt during TS 3 See Display Skip Generator for further information During time slot 4 two units of column current are encoded by R140 There is no row current encoded during this time siot this resuits in the numeral 1 being displayed on the crt Neither row nor column analog data is encoded during time slots 5 6 and 7 as defined by the Standard Readout Format During time slot 8 two units of column current and three units of row current are encoded by resistors R181 and R80 respectively This addresses the prefix in the Character Selection Matrix The final data output is provided from time siot 9 by R190 connected to the column output and R90 to the row output These resistors encode two units of column current and four units of row current to cause V volts symbol to be displayed Time slot 10 is not encoded in accordance with the Standard Readout Format The
341. d Whenever either of these sounds is heard turn off the 7904A and proceed with the Preliminary Procedure given below PRELIMINARY PROCEDURE WARNING To avoid electric shock always disconnect the instrument from the power source before removing or replacing components or plug in units 1 Remove all plug in units from the mainframe 2 Set the CONTROL ILLUMINATION switch on the rear panel to the OFF position and the GRAT ILLUM switch on the front panel to the fully counterclockwise position 3 Remove the power supply unit from the mainframe following the procedure given later in this section under Component Removal and Replacement 4 Connect the power cord plug of the 7904A to the output of a variable autotransformer which is set for 115 volts Connect the autotransformer to an isolation transformer and plug the isolation transformer into a 115 volt power source Maintenance 7904A TABLE 4 2 Recommended Power Supply Troubleshooting Sequence Proceed To Trouble Procedure Troubleshooting Symptom Step 7904A inoperative 1 Check line fuse no pulse mode 7904A inoperative 1 Check line input no pulse mode circuit line fuse open n 2 Check LV recti fier circuit 3 Check inverter circuit 1 Check inverter circuit 7904A inoperative no pulse mode line fuse normal 1 Isolate Power B suppiy malfunction from the main frame circuitry 7904A operating in the pulse
342. d by pulling on the wire leads this causes the locking mechanism to clamp onto the circuit board pins END LEAD MULTI PIN CONNECTOR END LEAD MULTI PEN CONNECTOR MULT I PiN CONNECTOR INDEX 1986 68 Figure 4 3 Orientation of multi pin connectors TROUBLESHOOTING EQUIPMENT The following equipment is useful for troubleshooting the 7904A Oscilloscope mainframe 1 Transistor Tester Description Dynamic type tester Purpose Test semiconductors Recommended type TEKTRONIX 577 177 Curve Tracer TEKTRONIX 576 Curve Tracer 7 1 Curve Tracer plug in unit and a 7000 oscilloscope system or a 5CT1N Curve Tracer plug in unit and a 5000 series oscilloscope system Digital Multimeter Description 10 megohm input impedance and 0 to 1 kilovolt range ac and dc ohmmeter accuracy within 0 1 Test probes must be insulated to prevent accidental shorting Purpose Check voltages and resistances Recommended type TEKTRONIX DM 501A Digital Multimeter requires TM 500 power module Test Oscilloscope Description Frequency response dc to 100 megahertz minimum deflection factor 5 millivolts to 5 volts division and 1 milliampere to 1 ampere division A 10X 10 megohm voltage probe should be used to reduce circuit loading for voltage measurements For current waveforms use a Tektronix P6021 Current Probe with passive termination or the equivalent Recommended type Refer to the Tektronix Prod
343. damage due to excessive power dissipation 3 63 Theory of Operation 7904A Several protection diodes are aiso included in this circuit Diode CR28 prevents the output of this supply from going more negative than about 0 6 volt if it is shorted to a negative supply Zener diode VR10 and diode CR10 supply a turn on voltage for U15 to start the 50 volt supply when the instrument is first turned on As soon as the 50 supply turns on CR10 stops conducting 15 V REGULATOR Basic operation of all stages in the 15 Regulator is the same as for the 50 Regulator The reference level for this supply is established to ground through R82 at pin 5 of 0848 The divider ratio of R80 and R81 sets a level of zero volts at pin 6 of 0848 The level on the 50 VS sense line is held stable by the 50 volt supply Any change at the output of the 15 volt supply appears at pin 6 of U84B as an error signal The output voltage is regulated in the same manner as described for the 50 volt supply Diode CR96 keeps the output of this supply from going more positive than about 0 6 voit if it is shorted to one of the more positive supplies Operational amplifier U84A provides current limiting for Q94 by monitoring the voltage drop across R95 When too much current is demanded from the supply the increased voltage drop across R95 allows to turn Q88 off reducing the current through Q94 5 V REGULATOR The operation of the 5 V Regulator
344. determined by the Delay Gate from A time base unit see main Interface diagram 3 Alternate Pulse Generator The third function of the Horizontal Logic stage is to produce an Alternate Pulse signal for use by the Plug In Binary and Vertical Binary stages The holdoff gate produced at the end of the sweep by the respective time base unit is differentiated by either C4335 or C4423 providing a positive going pulse to pin 6 or 9 of 04428 The differentiated or holdoff gate may preduce the alternate pulse depending upon the operating conditions as shown in Tabie 3 5 1 4 5 12 16 15 om om ALL OTHER COMBINATIONS OUTPUT LOCKOUT The following sections describe the operation of the Alternate Pulse Generator stage for the various combinations of input conditions shown in Table 3 5 1 A Only Mode An Alternate Pulse is produced at the end of each A sweep when the HORIZONTAL MODE switch is set to the position 2 B Oniy Mode In the B position of the HORIZONTAL MODE switch an Alternate Pulse is produced at the end of each B sweep The time base must be in independent nondelayed mode Theory of Operation 7904A TABLE 3 5 Input Output Combinations for Alternate Pulse U4428 Pin 8 dS Has effect this case ERAKAR WITH VERTICAL UNIT ALL OTHER COMBINATIONS OUTPUT A DELAYS B A A WITH VERTICAL UNIT IN B
345. dout System Detailed information on circuit operation is given later The key block in the Readout System is the Timer Stage see schematic 6 This stage produces the basic signals that establish the timing sequences within the Readout System The period of the timing signal is about 250 microseconds it drops to about 210 microseconds when Display Skip is received see detailed description of Timer stage for further information This stage also produces contro signals for other stages within this circuit and inhibit signals to the Vertical Amplifier Horizontal Amplifier and Logic circuits which allow readout display to be presented The Time Slot Counter stage receives a trapezoidal voltage signal from the Timer stage and directs it to one of ten output lines These output lines are labeled TS 1 through TS 10 time slots 1 through 10 and are connected to the vertical and horizontal plug in compartments as weil as to various stages within the Readout System The output lines are energized sequentially so there is a pulse on only one of the 10 lines during any 250 microsecond timing period After the Time Slot Counter stage has counted time slot 10 it produces an End of Word pulse which advances the system to the next channel Theory of 7904 Two output lines row and column are connected from each channel of the plug in unit back to the Readout System Data is typically encoded on these output lines by co
346. dout plug in units to operate with other plug in units makes it possible to process and monitor signals at the same time the digital measurement is being made For example by locating a frequency counter in one of the vertical compartments and an amplifier unit in the other vertical compartment the crt can display the trigger waveform superimposed on the displayed signal to indicate the actual triggering point Or if the counter is placed in a horizontal compartment a low amplitude signal can be applied to a vertical amplifier and amplified before it is internally routed by the trigger source switches to the counter trigger circuit This allows the unit to be used on signais too small to trigger other counters Programmable Digitizer Plug In Unit Installation of a Programmable Digitizer plug in unit such as a 7020 adds digital storage and full IEEE 488 bus capabilities to the 7904A Oscilloscope system Some major features that the Programmable Digitizer provides are multiple waveform storage in digital memory two cursors for point to point measurements pre and post trigger viewing storage and recall of up to six front panel settings and signal averaging to reduce noise The envelope mode allows subtle variations among random events to be captured and displayed Waveform storage using digital memory eliminates the need for a storage crt and also allows viewing information that occurred prior to the triggering event In addition
347. e Test Point Reading 130 V Step C Check the Pre Regulated Power Supplies To check the pre regulated power supplies perform the following procedure 1 Connect a 10X voltage probe from the test oscilloscope to resistor R84 on the A12 Control Rectifier board Refer to Access to Components in Power Supply for access to A12 Control Rectifier circuit board Refer to the component locator opposite diagram 14 in Section 8 Diagrams and Circuit Board Illustrations for the location of A12R84 Set the test oscilloscope vertical deflection factor as necessary for an on screen display set the horizontal sweep rate for 2 milliseconds division 2 Set the variable autotransformer for 115 volts Connect the 7904A power cord plug to the variable autotransformer turn on the 7904A 3 Compare the waveform on the test oscilloscope to those shown in Figure 4 4 If the waveform resembles that of Figure 4 4A proceed to Step E of this procedure If it resembles that of Figure 4 4B proceed with part 4 of this step 4 Remove the 10 voltage probe from R84 Set the test oscilloscope vertical coupling to dc and the horizontal sweep rate to 10 milliseconds division 5 Connect the 10X probe to each power supply at the Burst Voltage Test Points given in Table 4 4 For location of the Burst Voltage Test Points refer to the component locator for the A12 Control Rectifier Circuit Board located opposite Converter
348. e 5096 point on the falling edge of the waveform now displayed is within 0 2 divisions horizontally of the center line Indicates duty cycle of 50 within 0 296 5 47 Checks and Adjustment 7904A Part Hi Adjustment and Performance Check C5 CHECK A AND B SAWTOOTH OUTPUT SIGNALS NOTE If the preceding step was not performed first perform step C1 then proceed C5 SETUP CONDITIONS 7904A Controis SAWTOOTH A or B Switch SAWTOOTH Connector o v E Coaxial Cable Test Equipment Controls Test Oscilloscope Sweep Rate Vertical Deflection Vertical Mode Time Base 4593 515 a Connect the output connector to the test oscilloscope channel 1 vertical input one megohm input b CHECK that the slope of the test oscilloscope display rises 2 volts horizontal division within 1096 10 volt sawtooth for 10 division sweep on 7904 crt screen and that the sawtooth baseline is within one volt of ground c Move the time base to the B HORIZ compartment d Set the SAWTOOTH selector switch to the B position e CHECK the test oscilloscope display for 2 volts division of sweep within 1096 10 volt sawtooth for 10 division sweep on the 7904A crt screen and that the sawtooth baseline is within one volt of ground 5 48 C6 CHECK A AND B GATE OUTPUT SIGNALS NOTE If the preceding step was not performed first perform step C1 then proceed C6 SETUP CONDITIONS
349. e Single Shot Lockout stage remains LO to allow U2126 to operate in the free running mode until a LO is received at pin 8 of U2120C When this occurs the output level at pin 10 of U2120C does not change immediately However the Single Shot Lockout circuit is now enabled If the Channel Counter has not completed word 8 the Readout System continues to operate in the normal manner When word 8 is completed the negative going end of frame pulse is produced at pin 11 of U2250 as the Channel Counter shifts to the code necessary to display word one This pulse is applied to pin 3 of U2120A which produces a at pin 6 of U2120B because of the momentary LO at pin 2 The HI at pin 6 produces a LO at pin 4 which causes pin 9 of U2120C to go LO Because pin 8 is already LO pin 10 goes HI This disables the Timer stage so it operates in the Display skip mode The Single Shot Lockout stage remains in this condition until a positive going trigger pulse is applied to pin 8 of U2120C This trigger pulse produces a LO at pin 10 of U2120C to enable 02126 and disable U2120B Now the Timer stage can operate in the normal manner for another complete frame When word 8 is completed the Channel Counter produces another end of frame pulse to again lock out the Timer stage ENCODING THE DATA Data is conveyed from the plug in units to the Readout System in the form of an analog current level code The characters that can be selected by the encoded
350. e circuit board if possible If the ferrule remains in the circuit board remove the spare ferrule from the replacement pin and press the new pin into the hole in the circuit board If the ferrule is removed with the damaged pin clean out the hole using an anti static vacuum type desoldering tool and a scribe Then press the replacement pin with attached spare ferrule into the circuit board Position the replacement pin in the same manner as the original Solder the pin to the both sides of the circuit board 11 the original pin was bent at an angle to mate with a connector carefully bend the new pin to the same angle Replace the pin connector Maintenance 7904A o CABLE EYELET 22 4 RECEPTACLE HOLE SOCKET HOLE 1986 71 Figure 4 15 Coaxial end lead connector assembly Circuit Board Pin Sockets The pin sockets on the circuit boards are soldered to the back of the board To remove or replace one of these sockets first unsolder the pin use an anti static vacuum type desoldering tool to remove excess solder Then straighten the tabs on the socket and remove the socket from the board Place the new socket in the circuit board hole and press the tabs down against the board Solder the tabs of the socket to the circuit board be careful not to get solder inside the socket CAUTION The spring tension of the pin sockets ensures a good connection between the circui
351. e connections of each interface connector are also identified in diagram 3 schematic diagram of the Logic circuit is given on Diagram 4 in Section 8 of this manual Diagrams and Circuit Board illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use these stage names to further identify portions of the circuitry on Diagram 4 The Logic circuit develops control signals for use in other circuits within this instrument and any plug in units installed in the vertical and horizontal compartments These controi signals automatically Theory of Operation 7904A Go a Se al a al Ea KOGO LIN IIR eile EARN 15 HOLIMS 8 HOLIMS TVINOZIHOH HOLIMS 39unos HIDD V HOLIMS 39unos 9 HOLIMS AGOW TVOILH3A SLqdNU SNOILISOd HOLMS 13NVd 1NOH4 syndino sindu AVL 3 7 Theory of Operation 7904A ALT MODE HORIZ A GATE X COMPENSATION INHIBIT HORIZONTAL X COMPENSATION INHIBIT HORIZONTAL DELAY MODE CONTROL B HOLDOFF MAINFRAME CHANNEL SWITCH SIGNAL DISPLAY 8 ALT MODE HORIZ gt 1 X COMPENSATION INHIBIT B
352. e cycle per each two graticule divisions over the center eight graticule divisions NOTE it is important that the adjustment of R312 and R340 be balanced Therefore each resistor should be adjusted equally Set the time base Time Div to 10 ns division and the Mag to X10 time base unit sweep rate of 1 nanosecond division EXAMINE sine wave display for one cycle per graticule line over the center eight graticule divisions Checks Adjustment 7904A Part H Adjustment and Performance Check ADJUST 1 ns linearity adjustment C922 on the 7 ADJUST HORIZONTAL READOUT A28 Horizontal Amplifier Board for 1 cycle per each JITTER A28R240 graticule division over the center eight divisions of NOTE display If the preceding step was not performed first CHECK repeat the horizontal timing checks as perform step then proceed outlined in part d et E7 SETUP CONDITIONS INTERACTION if the timing parameters in part d are not met repeat parts e through of this step VERTICAL MODE HORIZONTAL a Test Equipment Controls Time Base Triggering Auto AC internal Sweep Rate vesci ores Vea bee teense 0 1 ms div a Set the READOUT INTENSITY for a visible readout display b readout display for minimum readout jitter c ADJUST LF Comp adjustment R240 on the A28 Horizontal Amplifier Board for minimum readout jitte
353. e display CHECK that graticule illumination occurs only after the time base has completed a sweep adjust GRAT ILLUM PRESET if necessary Set the GRAT ILLUM GATE or EXT switch to EXT CHECK that pressing the GRAT ILLUM MAN pushbutton causes one momentary illumination of the graticule Set the GRAT ILLUM control to midrange out of the PULSED detent position 5 49 Checks and Adjustment 7904A Part il Adjustment and Performance Check D TRIGGER SYSTEM Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 1 Test Oscilloscope 2 or 3 Amplifier 4 Time Base two required 10 Signal Standardizer 12 Coaxial Cable one 18 inch required 13 Coaxial Cable two 42 inch required 9 Plug in Extender rigid calibration fixture 01 TRIGGER SYSTEM PRELIMINARY SETUP a Perform the Adjustment and Performance Check Power Up Sequence D2 ADJUST A TRIGGER SELECTOR CENTERING A14R255 A14R270 A14R274 148279 First perform step D1 then proceed b Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for any modifications which may affect th s procedure ee SETUP CONDITIONS 7904A Controls No change in settings foldout pag Board lilustrations d Set the 7904 controis as follows POWER one VERTICAL RIGHT VERT TRA
354. e oscilloscope accuracy MN 0 C to 50 C Plug in gain set using the oscilloscope calibrator within 10 C of the operating temperature in a temperature range between 0 C and AIBA Opt 6 offset version Add 1 to accuracy figures when switched to OFFSET 1 13 General Information 7904A TABLE 1 8 7904A Oscilloscope Horizontal System Specification Performance Feature Deiayed Sweep Deiayed Sweep and Ext Amplifier Dual Sweep Delaying and Displayed Display Switching Delayed Sweep Time Base with Pre Trigger Acquire Clock for 7854 only Delayed Sweep Delaying Sweep TABLE 1 9 Special Purpose Plug in Units Plug in Unit 7CT1N 7001 7001 7D02 7002F 7D11 7D12 7D13A 7015 7020 7 11 715 1 14 Performance Feature Low Power Semiconductor Curve Tracer Logic Analyzer Logic Analyzer Digital Delay A D Converter plug in modules provide flexible measurement capability Measures Temperature Voltage Current and Resistance Universal Counter Timer Programmabie Digitizer CATV Preamplifier 20 Hz to 5 MHz Spectrum Analyzer 0 5 ns div Maximum Triggered Calibrated Frequency Sweep Rate Range 5 ns div De to 150 MHz 2 ns div i De to 200 MHz De to 200 MHz Dc to 500 MHz 1 ns div Dc to 400 MHz Dc to 400 MHz Dc to 400 MHz 0 5 ns div Dc to 700 MHz 0 5 ns div H De to 700 MHz TABLE 1 9 CONT Speciai Purpose Plug in Units Plug
355. e plug in called for a shift in prefix the CRT readout would be changed to 1mV zeros deleted by program see Encoding the Data The 100 microamperes of quiescent current through R2242 provided by Q2243 see Display Skip Generator allows the prefix to be shifted from m 100 microamperes of column current column 1 to no prefix 0 column current column 0 so only the unit of measurement encoded during time slot 9 is displayed Notice that reducing the prefix program from column 1 to column 0 programs the Readout System to not display a character at this readout location further feature of the Zeros Logic and Memory is the Iden tify function If 10 units of column current are encoded by the plug in unit along with row 3 during time slot 1 the Ze ros Logic and Memory produces a negative going output puise at pin 1 to switch the Column Data Switch and Row Data Switch to the ninth channel Then time slot pulses 2 through 9 encode an output current through resistors R2191 through R2199 for column data and enable pin 10 of 02186 This provides the addresses necessary to display the word IDENTIFY in the word position allotted to the channel that originated the Identity command After comple tion of this word the Column Data Switch and Row Data Switch continue with the next word in the sequence 3 48 The end of word signal from the Time Slot Counter is con nected to pin 9 of U2232 through C2239 At the end of each word of readout info
356. e the protective cover from the power supply unit see Access to Components in Power Supply Unit 3 Remove At2 Control Rectifier board using the previous procedure 4 Remove the 5 securing screws from A23 Power Supply Inverter board 5 Unsolder the 5 line input leads from the circuit board Remove the excess solder from these circuit board pads with a vacuum type anti static desoldering tool 6 Remove the two power transistors by removing the securing screws and pulling the transistors from the ceramic heatsinks 7 Remove the A23 Power Suppiy Inverter board from the power supply unit 8 To replace the A23 Power Supply Inverter board reverse the order of removal Match the index arrow on the pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown on the circuit board illustration in Section 8 Diagrams and Circuit Board Illustrations PLUG IN INTERFACE CONNECTORS The individual contacts of the plug in interface connectors can be replaced However we recommend replacing the entire A6 Main Interface board if a large number of the contacts are damaged An aiternative solution is to refer the maintenance of the damaged 6 Main Interface board to your local Tektronix Office Use the following procedure to remove and replace an individual contact of the plug in interface connectors The plug in interface contacts which mounted on the Follower circ
357. e the tinted filter leave the clear plastic face protector implosion shield installed and replace the mask The face plate protector should be left in place at all times to protect the crt face from scratches and the operator from crt implosion SECOND CENTER TENTH VERTICAL VERTICAL VERTICAL LINE CENTER HORIZONTAL 1675 7 Figure 2 3 Definition of graticule measurement lines WARNING Do not remove the clear plastic implosion shield covering the crt face plate the implosion sh eld provides protection to the operator from crt implosion An optional mesh filter is available from Tektronix included with Option 3 This filter provides shielding against radiated electromagnetic interference from the face of the crt also serves as a light filter to make the trace more visible under high ambient light conditions The mesh filter fits in place of the plastic tinted filter Order the filter by Tektronix Part 378 0603 00 CONTROL ILLUMINATION The CONTROL ILLUMINATION switch located on the rear panel sets the illumination level of the A and B INTENSITY indicators the A and B TRIGGER SOURCE switches and of the lighted pushbutton switches on the plug in units The positions available are OFF MEDIUM and HIGH The CONTROL ILLUMINATION switch does not affect the function indicator lights such as the triggered or single sweep ready lights INTENSITY CONTROLS The INTENSITY con
358. e transistor self heating is aggravated OUTPUT AMPLIFIER The output amplifier consists of 2 thin film Hybrid wideband amplifiers U415 0515 and their associated bias circuitry These amplifiers provide a voltage gain of 4 and 10 respectively resulting in overall voltage gain from J10 and 9 to the crt vertical deflector of about 40 signal path interconnections between and within hybrids are made with 50 ohm strip transmission lines via the HYPCON system Integrated circuit 0415 receives the delayed and compensated signal from the delay line compensation stage at input pins 7 and 9 Variabie resistor R211 provides vertical amplifier gain adjust by shunting the differential signal Trimmers C401 R405 and R404 are transient response adjustments effective in the first 10 nanoseconds of the step response Bias current for 0415 is supplied by U700B U700A and associated circuitry operate as a power supply to maintain a constant common mode dc level at the input to U515 regardless of current demand from 0415 The BEAMFINDER switch when depressed changes the current source for U515 to provide the BEAMFINDER function Normally the current source for U515 is supplied from the 15 V supply through Q422 diagram 10 However when the BEAMFINDER switch is actuated Q422 is turned off so the only current source for U515 is through R712 This limits the dynamic range of the stage by limiting its available current so the di
359. eaned as follows 7904 1 the mesh filter in a vertical position and brush lightly with a soft No 7 water color brush to remove light coatings of dust or lint 2 Greasy residues or dried on dirt can be removed with a solution of warm water and a neutral pH liquid detergent Use the brush to lightly scrub the filter 3 Rinse the filter thoroughly in clean water and allow to air dry 4 If any lint or dirt remains use clean low pressure air to remove it Do not use tweezers or other hard cleaning tools on the filter as the special finish may be damaged 5 When not in use store the mesh filter in a lint free dust proof container such as a plastic bag INTERIOR Cleaning the interior of the instrument should only be occasionally necessary The best way to ciean the interior is to blow off the accumulated dust with dry low velocity air approximately 5 Ib in Remove any dirt which remains with a soft brush or a cloth dampened with mild detergent and water solution A cotton tipped applicator is useful for cleaning in narrow Spaces or for cleaning more delicate circuit components CAUTION S S S PS as P Circuit boards and components must be dry before applying power to prevent damage from electrical arcing The high voltage circuits should receive special attention Excessive dirt in this area may cause high voltage arcing and result in improper instrumen
360. ed when the VERTICAL MODE switch is set for ALT When this output level is the RIGHT VERT unit is displayed when it is LO the LEFT VERT unit is displayed the ALT or CHOP positions of the HORIZONTAL MODE switch nondelayed operation only the output of this stage is slaved to the output of the Horizontal Binary stage so that the Vertical Alternate Command is always when the Display B Command is LO and vice versa This action allows independent pairs operation sweep siaving in the ALT position of the VERTICAL MODE switch and the ALT or CHOP positions of the HORIZONTAL MODE switch whereby the LEFT VERT unit is always displayed at the sweep rate of the B time base and the RIGHT VERT unit is displayed at the sweep rate of the A time base Thus independent pairs operation can simulate dual beam operation for repetitive sweeps When the A time base unit is set to the delaying mode the repetition rate of the Vertical Alternate command is one half the repetition rate of the Display B Command Consequently each vertical unit is displayed first against the A time base unit delaying then the time base unit delayed before the display is switched to the other vertical unit The Vertical Aiternate Command is used in the Plug in Binary and Vertical Mode Logic stages The Vertical Binary stage U4368 uses the same type of 1 as the Horizontal Binary stage Notice the Display B command level at pin 7 This input is the inve
361. ellaneous S Sampling unit T Sampling time base unit The third and fourth digits of the plug in type number do not carry any special connotation A suffix letter added to the normal four digit type number identifies a unit not equipped with the circuitry necessary to encode data for the 7000 series readout system Table 1 6 lists any incompatibilities with the variety of plug in units availabie for use with the 7904A Oscilloscope Table 1 7 lists the vertical specifications which are system dependent For more complete specifications on piug in units for the 7000 series oscilloscope system refer to the Tektronix Products catalog Table 1 8 lists the horizontal specifications which are system dependent For more complete specifications on plug in units for the 7000 series oscilloscope system refer to the Tektronix Products catalog Table 1 9 lists some special purpose plug in units available for use with the 7904A Oscilloscope TABLE 1 6 Plug in incompatibilities Operating Conditions Symptoms No Display Leading edge of triggering waveform cannot be viewed The 7904A Oscilloscope is compatible with Tektronix 7000 series Plug In units with the exceptions listed in the following table Cause mm rat ra re RETINOL No vertical signal connection 7904A delay line length 7904A Horizontal Mode 7B51 alternates when both will reset 7870 i horizontal time base 7871 units are set for
362. ent and Performance Check CHECK crt display amplitude for 0 1 division or less of the 500 MHz signal verifies isolation of at least 80 1 at 500 MHz Move the amplifier unit to the LEFT VERT compartment without changing any settings Set the VERTICAL MODE switch to RIGHT CHECK crt display amplitude for 0 1 division or less of the 500 MHz signal verifies isolation of at least 80 1 at 500 MHz Disconnect the high frequency sine wave generator Set the VERTICAL MODE switch to LEFT Connect the medium frequency sine wave generator to the amplifier input Set the medium frequency sine wave generator for eight divisions of deflection at 100 megahertz Set the VERTICAL MODE switch to RIGHT CHECK crt display amplitude for 0 05 division or less of 100 megahertz signal verifies 100 megahertz isolation of at least 160 1 Move the amplifier to the RIGHT VERT compartment without changing any settings Set the VERTICAL MODE switch to LEFT CHECK crt display amplitude for 0 05 division or less of 100 megahertz signal verifies isolation of at least 160 1 from to 100 megahertz 5 67 Checks and Adjustment 7904A Part li Adjustment and Performance Check F10 CHECK VERTICAL DISPLAY MODES F11 CHECK VERTICAL TRACE SEPARATION NOTE B OPERATION NOTE if the preceding step was not performed first perform step F1 then proceed If the preceding step was not performed first perform step F1 then proceed
363. er goes LO and 15 inverted by U2157D to advance the Horizontal Character Position Counter No character could be displayed in this situation as no character information is stored at the Character Generator addresses formed using row 10 Time siots 1 2 and 3 are also connected to the Space instruction through VR2185 VR2186 and VR2187 respec tively This configuration adds a space to the displayed word during time slots 1 2 and 3 even if information is not encoded during these time slots With this feature the in formation which is displayed during time siot 4 1 2 5 data always starts in the fourth character position whether data has been displayed in the previous time siots or not There fore the resultant CRT display does not shift positions as normal invert or cal uncal information is encoded by the plug in DECIMAL POSITION LOGIC The Decimal Position Logic stage allows decimal points to be displayed at five possible locations within a readout word see Fig 3 18 The decima location encoded by a plug in during time siot one is achieved by adding positioning cur rent to the X horizontal readout signal Circuitry for this stage includes five 2 input NOR gates in U2157 and U2251 with precision resistors connected to their outputs One in put of each NOR gate is connected to row 7 on the Row Decoder and the other to one of columns 3 through 7 on the Column Decoder When a decimal is to be displayed row 7 goes LO and disabl
364. er remains open at least 0 5 second after the sweep is completed to photograph the entire readout and graticule INTENSITY MODULATION Intensity Z axis modulation can be used to relate a third item of electrical phenomena to the vertical Y axis and the horizontal X axis coordinates without affecting the waveshape of the displayed signal This is accomplished by changing the intensity of the displayed waveform to provide a gray scale display The voltage amplitude required for visible trace modulation depends on the setting of the A and B INTENSITY controls two voit peak to peak signal will completely blank the display even at maximum intensity levels lower amplitude signals can be used to change only the relative trace brightness Negative going signals increase the display intensity and positive going signals decrease the display intensity Refer to Table 1 3 in the General Information section for specifications on Z axis signal requirements Time markers applied to the rear panel Z AXIS INPUT connector provide a direct time reference on the display With uncalibrated horizontal sweep or X Y mode operation the time markers provide a means of reading time directly from the display if the markers are not time related to the display waveform use a single sweep display REMOTE INPUT SIGNALS The signal source required to operate the remote input functions on the rear panel can be either active pulse generator logic
365. erformance Check Power Up Sequence Refer to Section 6 Instrument Options and the Change information at the rear of this manual for any modifications which may affect this procedure POWER 5 On VERTICAL MODE RIGHT VERT TRACE SEPARATION Midrange A TRIGGER SOURCE VERT MODE Midrange HORIZONTAL MODE B 5 amp Midrange B TRIGGER SOURCE VERT MODE FOCUS d des ueque Midrange READOUT ise kr Ren OFF in detent GRAT LLUM As desired BEAMFINDER Pushbutton out F2 ADJUST VERTICAL AMPLIFIER CENTERING A18R738 A16R535 NOTE First perform step F1 then proceed F2 SETUP CONDITIONS 7904A Controis VERTICAL 4 Test Equipment Controis Time Base Sweep Rate Triggering 4593 535 Set the A INTENSITY control as desired EXAMINE the vertical position of the alternating traces might appear as a single trace they should be within 0 5 division of the graticule center line Set the VERTICAL MODE switch to LEFT ADJUST MVA Center adjustment R736 on the A18 Vertical Amplifier Board to align the trace with the center graticule line Set the VERTICAL MODE switch to RIGHT ADJUST Right Ctr adjustment R535 on the A16 Vertical Cha
366. es the Horizontal Character Position Counter by keeping the four outputs of U2264 LO It also sets one input of each of the five NOR gates to LO One of columns 3 through 7 also goes LO depending on which decimal position is encoded causing the NOR gate to which its connected to go This high adds current to the X horizontal signal in the amount determined by the resistor connected to the NOR gate s output Each Character Gen erator location addressed by row 7 and column 3 through 7 contains information necessary to form a decimal point on the CRT in the position indicated The Horizontal Character Position Counter resumes norma operation and the Deci mai Position Logic is disabled when row 7 goes back up at the end of the time siot Some plug ins require decimal poinis at locations in the readout word other than the five provided by the Decimal Position Logic stage An additional decimal point can be dis played any position normally available to characters by encoding row 8 with column 9 The Horizontal Character Position Counter provides positioning current in this mode and the Decimal Position Logic stage is disabled REV NOV 1985 VECTOR GENERATORS 7 The Y Vector Generator is in two stages and consists of U2210A and B Vertical character size adjustment is pro vided with R2210 as a variable feedback resistor for U2210A Input to the Vector Generator is provided by the three bits of vertical character information from
367. etal encased diodes can be identified by the diode symbol marked on the body SEMICONDUCTOR LEAD CONFIGURATIONS Lead configurations for semiconductor devices used in the 7904A Oscilloscope are shown in Figure 4 2 STATIC SENSITIVE DEVICES pours CAUTION ame Static discharge can damage any semiconductor component in this instrument This instrument contains electrical componenis that are susceptible to damage from static discharge See Table 4 1 for relative susceptibility of various classes of semiconductors Static voltages of 1 kV to 30 kV are common in unprotected environments Observe the following precautions to avoid damage 1 Minimize handling of static sensitive components 2 Transport and store static sensitive components or assemblies in their original containers on a metal rail or conductive foam Label any package that contains static sensitive assemblies or components 3 Discharge the static voltage from your body by wearing a wrist strap while handling these 4 3 7904 COLOR CODE METAL FILM E CERAMIC COMPOSITION RESISTORS CAPACITORS RESISTORS D and 157 2ND AND 3RD SIGNIFICANT FIGS AND OR f COLOR CODE MAY NOT MULTIPLIER TOLERANCE PRESENT ON SOME CAPACITORS 19 TEMPERATURE COEFFICIENT RESISTORS CAPACITORS SIGNIFICANT FIGURES TOLERANCE OVER 10pF UNDER 10pF OVER 10
368. eter reading is 12 voits h Disconnect the DVM 5 44 Checks and Adjustment 7904A Part H Adjustment and Performance Check C CALIBRATOR AND OUTPUT SIGNALS Equipment Required 1 Test Oscilloscope 4 Time Base 5 Precision DC Voltmeter DVM 1i Time Mark Generator Ci CALIBRATOR AND OUTPUT SIGNALS PRELIMINARY SETUP a Perform the Adjustment and Performance Check Power Up Sequence b Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure foldout page in Section 8 Diagrams and Circuit Board illustrations d Set the 7904A controls as follows POWER SWHOW REOR SR On VERTICAL RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE A INTENSITY Fuily counterclockwise HORIZONTAL MODE amp Fully counterclockwise B TRIGGER SOURCE VERT MODE READOUT INTENSITY OFF in detent GRAT ILLUM Midrange BEAMFINDER Pushbutton out CALIBRATOR 4 V pushbutton in Numbers correspond to those listed in Table 5 3 Test Equipment 18 Coaxial Cabies four 42 inch required 15 Adapter BNC T 19 Tool Alignment ir C2 CHECK ADJUST CALIBRATOR OUTPUT VOLTAGE A5R385 NOTE First perform step C1 then proceed
369. evel is LO Channel 1 can be displayed The Horizontal Chopped Blanking signal at pin 4 is connected through LR4338 to the Horizontal Binary stage U4358 and to the Z Axis Logic stage U4485 by way of Q4336 When this signal is Hl the crt is unblanked to display the selected signal When it is LO the crt is blanked to allow switching between the horizontal units VERTICAL MODE LOGIC The Vertical Mode Logic stage is made up of discrete components CR4323 CR4322 CR4369 CR4368 and buffer Q4382 Q4392 These components develop the Display Right Command which 5 connected to the Main Interface Vert cal Interface and Trigger Selector circuits to indicate which vertical unit is to be displayed When this output level is the RIGHT VERT unit is displayed when it is LO the LEFT VERT unit is displayed Theory of Operation 7904A The VERTICAL MODE switch shown on Diagram 2 provides control levels to this stage This switch provides a Hi level on only one of five output lines to indicate the selected vertical mode the remaining lines are LO Notice that only four of the lines from the VERTICAL MODE switch are connected to the Logic circuit Operation of this stage is as follows When the VERTICAL MODE switch is set to RIGHT a HI level is connected to the base of 04382 through R4321 This forward biases Q4382 and the positive going level at its emitter is connected to the emitter of Q4392 The collector of Q4392 goes HI to indicate that
370. ew 130 nanoseconds from step Rise time of the pulse should be 600 picoseconds between the 10 and 9096 points c ADJUST High Frequency compensation as given in Table 5 7 The High Frequency Compensation adjustments are located on the 18 Vertical Amplifier Board Checks and Adjustment 7904A Part il Adjustment and Performance Check TABLE 5 7 High Frequency Compensation Adjustment MMC Adjust For ets Ling See Part b Adjustment ume for detailed From 50 adjustment point of step A18R404 First 5 ns Optimum rise 18 405 time and flat A18C401 top with abberations not to exceed 0 3 div p p R83 on 79044 chassis First 7 ns Time base unit sweep rate at 10 ns div Minimum slope R83 INTERACTS with Vert Gain adjustment 18R211 A18R215 A18C215 Best front corner and minimum abberations Adiust rise time for 600 ps or less Best flat top A18L100 From 2 ns to 5 ns E A d INTERACTION adjustments in step F7 interact with steps F3 F4 and F5 repeat as necessary e Move the signal standardizer to the RIGHT VERT compartment and set the VERTICAL MODE switch to RIGHT f EXAMINE displayed pulse for optimum square corner and flat top with aberrations within the limits given in part b g INTERACTION if necessary compromise the High Frequency Compensation Adjustments g
371. f time base unit Notice that under these conditions both channels of the LEFT VERT unit are displayed at the B sweep rate and that both channels of the RIGHT VERT unit are displayed at the A sweep rate Input conditions when ihe VERTICAL MODE switch is set at ALT are Pin 4 LO VERTICAL MODE switch set to ALT Pin 8 HI or LO Plug In Alternate Command signal changes state during to LO transition of the Vertical Alternate Command signal Table 3 9 gives the input output combinations for the Plug In Binary stage VERTICAL CHOPPED BLANKING Part of integrated circuit U4320 along with the external components shown in Figure 3 3 make up the clock generator stage Component parts 1 01 Q2 represent an equivalent circuit within U4320 This circuit along with discrete components C4314 R4312 R4313 R4314 compose a two megahertz free running oscillator to provide a timing clock signal which synchronizes the vertical horizontal and plug in chopping modes This stage operates as follows Assume that Q2 is conducting and Q1 is off The collector current of Q2 produces a voltage drop across R1 to turn off Q1 This negative level at the collector of Q2 is also connected to pin 14 through Q3 see waveforms in Fig 3 3B at time T9 Since there is no current through Q1 C4314 begins to charge towards 15 volts through R4312 R4313 The emitter of Q1 goes negative as C4314 charges until it reaches a level about 0
372. fective Dscont Name amp Description Code Mfr Part Mo 180430 151 0192 00 TRANSISTOR SELECTED 04713 5 58801 180431 151 0192 00 TRANSISTOR SELECTED 04713 5 58801 180435 151 0215 00 TRANSISTOR PNP S1 TO 92 04713 SPS8803 A18Q530 151 0216 00 TRANSISTOR PNP SI TO 92 04713 5 58803 180540 151 0301 00 TRANSISTOR PNP SI TO 18 04713 ST898 A18Q541 151 0302 00 TRANSISTOR NPN SI TO 18 04713 51899 180630 151 0221 00 TRANSISTOR PNP SI TO 92 80009 151 0221 00 180631 151 0367 00 TRANSISTOR 51 55 04713 5 5 8811 180720 151 0390 00 TRANSISTOR NPN SI X 81 04713 5 5341408 5045 A18Q722 151 0126 00 TRANSISTOR NPN SI TO 18 04713 ST1046 180740 151 1021 00 TRANSISTOR N CHAN SI 0 18 80009 151 1021 00 A18R130 311 1230 00 RES VAR NONW 20K 0 5 32997 3386 04 203 Ai8R131 311 1214 00 RES VAR NONW TRMR 200K OHM 0 5W 32997 3386 104 204 18 132 311 1214 00 RES VAR NONW 200K OHM 0 5W 32997 33885F 104 204 188201 315 0101 00 RES FILM 100 5 0 250 57668 NTR25J E 100E 188205 322 0133 00 5 237 OHM 1X 0 25W TC TO 75042 CEBTO 2370F 188206 321 0331 00 RES FXD F1LM 27 4K OHM 1 0 125W TC T0 19701 5043 027 0 A18R207 321 0171 00 RES FILM 590 OHM 125 0 125W TC TO 19701 5033 059080 A18R208 317 0047 00 RES FXD CMPSN 4 7 OHM 5 0 129W 01121 884765 Ai8R209 317 0100 00 RES FXD CMPSN 10 OHM 5 0 125W 01121 8810
373. ferential pairs is reduced When readout is displayed the X Readout signal is applied to the Horizontal Amplifier through J12 At the same time the X Y Inhibit signal causes Q140 to turn on enabling the Readout Centering adjustment R114 The readout display may now be horizontally positioned DRIVER AMPLIFIERS AND ACTIVE PEAKING The left and right Driver Amplifiers each consist of a inverting transistor stage followed immediately by an Active Peaking network Transistors Q620 and Q640 make up the right and left Driver Amplifier stages respectively Both act as shunting feedback amplifiers converting current signals at their bases to low impedance voltage signals at their collectors The Active Peaking networks are composed of 0621 Q630 and related components Because operation of teft and right Active Peaking circuits is identical only a discussion of the right Active Peaking circuit follows The signal at the collector of right Driver Amplifier Q620 is coupled through R722 to the bases of Q810 Q820 of the right output Amplifier stage and to the base of Q621 of the right Active Peaking circuit Transistor Q621 is connected as an emitter follower providing current gain which is coupled through R722 C810 and C811 to the input of the right Output Amplifier This signa current differentiated by C810 and C811 is added to the dc coupled signal current passing through R722 providing the current necessary to charge the
374. flection systems The Ready signal derived from this output is connected to the Decimal Point Logic and Character Position Counter stage and the Format Generator stage The Z Readout output at pin 12 is produced next This current is connected to the crt circuit to unblank the crt to the intensity level determined by the voltage on the Gate Readout Intensity line The Character Scan ramp at pin 16 started to go negative as this timing sequence began However character generation does not start until the readout intensity level has been established The triangular Character Scan ramp runs from about 2 volis to about 8 5 volts then returns back to the original level This waveform provides the scanning signal for the Character Generator stages Character Scan adjustment R2128 sets the dc level of the Character Scan ramp complete characters on the display The Timer stage operates in one of two modes as controlled by the Display Skip level at pin 4 The basic mode just described is a condition that does not occur uniess all ten characters of each word 80 characters total are displayed on the crt Under typical conditions only a few characters are displayed in each word The Display Skip level at pin 4 determines the period of the Timer output signal When a character is to be generated pin 4 is LO and the circuit operates as just described However when a character is not to be displayed a level is applied to pin 4 of U2126
375. for display the internal signal must be time related to the display signal in order to obtain a triggered stable display CALIBRATOR OUTPUT The CALIBRATOR provides a convenient signal for checking basic vertical gain and sweep timing The calibrator signal is also useful for adjusting probe compensation as described in probe instruction 2 13 Operating Instructions 7904A manuals addition the calibrator can be used as a convenient signal source for application to external equipment Voltage The CALIBRATOR provides accurate output voltages of 40 millivolts 0 4 volt and 4 volts into high impedance loads lt 100 In addition it provides 4 mililivolts 40 millivolts and 0 4 volt into 50 ohm loads Current The optional current joop accessory provides a 40 milliampere output current the CALIBRATOR must be set for a 4 volt output which may be used to check and calibrate current measuring probe systems The current signal is obtained by clipping the probe around the current loop use the current loop adapter accessory part 012 0341 00 Repetition Rate The repetition rate of the CALIBRATOR is 1 kilohertz The calibrator circuit uses frequency stable components to maintain accurate frequency and a constant duty factor Thus the CALIBRATOR can be used for checking the basic sweep timing of time base units 1 kHohertz rate only Wave Shape The square wave output signal of the CALIBRATOR can be used
376. fore connecting the instrument to the line voltage source TABLE 1 2 Power Cord and Plug identification Information 1 Plug U Nominal Reference Option Configuration sage Line Voltage Standards ption North American ANSI C73 11 120V 15A 120 V NEMA 5 15 STANDARD iEC 83 Universal Euro CEE 7 Il iV VII 220V 16A 240 83 i UK BS 1363 240V 13A 240 V HEC 83 240 846 C112 ANSI C73 20 North American 2 6 15 4 240V 15A 240 SEM 6 15 IEC 83 220 V 5 ANSi Amer can National Standards Institute NEMA National Electrical Manufacturer s Association IEC International Electrotechnical Commission CEE International Commission on Rules for the Approval of Electrical Equipment 1 2 585 British Standards institution 5AS Standards Association of Australia TSEV Schweizevischer Elektrotechischer Verein This instrument operates from single phase power source and has a detachable three wire power cord with a two pole three terminal grounding type plug The voltage to ground earth from either pole of the power source must not exceed the maximum rated operating voltage 250 volts Before making connection to the power source determine that the instrument is adjusted to match the voltage of the power source and has a suitable
377. g the trace to the graticule center line Do not change the test oscilloscope Position control after setting this ground reference b Connect the front panel SIG OUT connector to the vertical input of the test oscilloscope with the 42 inch 50 ohm coaxial cable Checks and Adjustment 7904A Part li Adjustment and Performance Check Set the test oscilloscope input coupling switch to dc CHECK test oscilloscope display for a dc level within 1 division of the ground reference established in part a ADJUST Signal Out DC Center adjustment R485 on the A14 Trigger Selector Board for a dc level within 1 division of the ground reference level install the signal standardizer in the LEFT VERT compartment Set the Test selector to Trigger Step Resp and the Rep Rate to 1 KHz Rotate the signal standardizer Position and Amplitude controls to display a six division triggered signal on the test oscilloscope EXAMINE the test osciloscope square wave display for optimum flat top within 0 1 division ADJUST the Signal Out Thermal 1 adjustment R480 on the Ai4 Trigger Selector Board to optimize the test oscilloscope square wave display Set the signal standardizer Rep Rate to 10 kHz Set the test oscilloscope sweep rate to 50 microseconds division EXAMINE the test oscilloscope square wave display for a flat top within 0 2 division ADJUST the Signal Out Thermal 2 adjustment R490 on the 14 Trigger
378. ge 6 Set the FOCUS control so the sine wave trace is as thin as possible 7 Adjust the ASTIG adjustment so the sine wave trace is as thin as possible 8 Repeat steps 6 and 7 for the best overall focus BEAMFINDER The BEAMFINDER helps to locate a display that overscans the crt viewing area vertically and or horizontally When the BEAMFINDER button is pressed the display is compressed and defocused within the graticule area To locate and reposition an overscanned display use the following procedure Operating instructions 7904A 1 Press the BEAMFINDER button While the display is compressed adjust the vertical and horizontal Position controls to center the display Change the vertical deflection factor until the deflection is about four divisions the horizontal deflection needs to be reduced to approximately six divisions when operating in an X Y mode 2 Release the BEAMFINDER button the display should remain within the graticule area TRACE ALIGNMENT The TRACE ROTATION adjustment allows the trace to be aligned with the horizontal graticule lines To adjust TRACE ROTATION first set the amplifier unit input to ground and then position the trace to the center horizontal graticule line Adjust the TRACE ROTATION so that the trace is paralle with the center horizontal graticule line Return the amplifier unit input to AC READOUT DISPLAY The Readout System provides an aiphanumeric display of information on the
379. gnal Standardizer Fest Leads Test Equipment Controls Signal Standardizers Vert or Horiz Freq Resp Position Midrange Precision Voltmeter a Connect the precision dc voltmeter DVM between test point TP183 located on the A21 Z Axis Board and chassis ground and note the voltage reading b EXAMINE crt display while advancing the A INTENSITY control setting A spot on the crt should become barely visible at 3 6V to 4 4V above the voltage noted in part a Set the A INTENSITY control so that the dc voltage at TP183 is 4 volts above the voltage noted in part a d Disconnect the DVM e ADJUST Grid Bias Adjustment R65 located on the A20 High Voltage Board to barely extinguish the spot on the crt 5 43 Checks 79044 Part li Adjustment and Performance Check B9 ADJUST AUTO FOCUS AMPLIFIER B10 EXAMINE EXTERNAL Z AXIS OPERATION GAIN A21R63 NOTE NOTE If the preceding step was not performed first If the preceding step was not performed first perform step B1 then proceed perform step B1 then proceed B10 SETUP CONDITIONS B9 SETUP CONDITIONS 7904A Controis READOUT intensity HORIZONTAL MODE A INTENSITY 7904A Controis A INTENSITY Fully clockwise Precision DC Volimeter DVM Low Frequency Sine Wave Generator d g d 5 o a Ge g H 5 v Time Base Test Leads Test Equipment Controls Time Base Sweep Rate 10 ns div T
380. gnal being displayed on the TABLE 2 1 Display Combinations Vertical Mode Horizontal Mode Comments LEFT One trace vertical deflection from single unit horizontai deflection from single unit Two traces vertical deflection from single unit horizontal deflection from both units Two traces vertical deflection from both units horizontal deflection from single unit Two traces vertical deflection from both units horizontal deflection from both units One trace vertical defiection shows algebraic summation of signals from both units horizontal deflection from single unit Two traces vertical deflection shows algebraic summation of signals from both units horizontal deflection from both horizontal compartments Two traces vertical deflection shows signals from both units horizontal deflection from single unit Four traces vertical deflection shows signals from both units horizonta deflection from both units One trace vertical deflection shows signal from single unit horizontal deflection from single unit Two traces vertical deflection shows signal from single unit horizontal deflection from both units Combinations given for single channel vertical and horizontal units only 2 11 Operating instructions 7904A crt This provides a stable display of two unrelated signals but does not indicate the phase relationship between the s
381. gnal while the readout display is presented on the crt ADD NOV 1985 CHANNEL SWITCH The Channel Switch stage consists primarily of U518 The differential horizontal signal from the A HORIZ plug in compartment is applied to pins 2 and 15 The differential horizontal signal from the B HORIZ plug in compartment is applied to pins 10 and 7 The Display B control signal determines whether the or B horizontal signal is coupled to the output pins 12 and 13 When the Display B control signal at pin 4 of U518 is the signal from the B plug in is coupled to the output When the Display B control signa is LO the signal from the A plug in is coupled to the output When the X Y Inhibit command at pin 6 of U518 is LO signals from the horizontal plug ins may be transferred to 0518 output as just described If the X Y Inhibit command is 0518 is disabled and no signals may be transferred through the device X Y DELAY COMPENSATION OPTION 2 The X Y Delay Compensation network is an optional feature For instruments not equipped with this option ihe horizontal signals from the plug in units are connected directly to the Horizontal Channel Switch through the Horizontal interconnect board When installed the X Y Delay Compensation network provides delay for the horizontal signals from the A and B HORIZ plug in compartments to match the delay of the vertical signal produced by the vertical Delay Line diagram 9 The delay compensa
382. gs in the following discussion use the stage names to further identify portions of the circuitry on diagram 11 INPUT AMPLIFIER The Input Amplifier stage consists of an FT doubler Beamfinder and readout positioning circuitry Two differential pairs of transistors Q320 0321 and Q330 Q340 plus two common base amplifiers comprise the FT doubler The signal from the Horizontal Channel Switch is connected to the bases of Q320 and Q340 The gain of this input stage is controlled by the emitter resistors of the differential pairs Overall gain is set by the Horizontal Gain adjustment R230 High frequency adjustments are also provided in the differential pair emitters Horizontal centering adjustment R121 balances the base currents of Q320 and Q340 to horizontally center the display 3 55 Theory of Operation 7904A The emitter current for the differential pairs is normally supplied from 15 volts through 0400 diagram 10 However when the front panel BEAMFINDER switch is pressed Q400 turns off and R530 must now supply the emitter current This results in less emitter current which reduces the dynamic range of the differential pairs to keep the horizontal display confined to the screen Also the current now flowing in R530 pulls the base of Q410 negative turning the transistor on The bias currents for Q620 and Q640 bases are maintained by the current through Q410 at nearly the normal level even though the emitter current of the dif
383. gurations of semiconductors used in this instrument are shown earlier in Figure 4 2 Some plastic case transistors have lead configurations which do not agree with those shown If a replacement transistor is made by a different manufacturer than the original check the manufacturers basing diagram for correct basing All transistor sockets in this instrument are wired for standard basing as used for metal cased transistors When removing soldered on transistors use an anti Maintenance 7904A static vacuum solder extractor see Soldering Techniques in this section to remove the solder from the circuit board pads Transistors which have heat radiators or are mounted on the chassis use silicone grease to increase heat transfer Replace the silicone grease on both sides of the insulating washer when replacing these transistors WARNING Handle silicone grease with care Avoid getting the silicone grease in your eyes Wash hands thoroughly after use To replace one of the power transistors mounted on the heatsink at the rear of the power supply unit first remove the mounting hardware Then unsolder and remove the defective transistor When replacing the transistor be sure to install the insulating washer between the transistor and the heatsink use silicone grease as previously described Tighten the mounting nut just tight enough to hold the transistor in place Then solder the replacement transistor to the A22 Low Voltage Reg
384. h is in either the ALT or the CHOP position and the time base units are in the independent mode TRIGGERING 30 31 32 Set the VERTICAL MODE switch to LEFT and the HORIZONTAL MODE switch to A Center the display on the crt with the left amplifier unit Position controi Disconnect the input signal from the right amplifier unit input connector Sequentially select all of the VERTICAL MODE switch positions Notice that a stable display is obtained for all positions of the VERTICAL MODE switch a straight line is displayed when in the RIGHT switch position Set the A TRIGGER SOURCE switch to LEFT VERT Again sequentially select all of the VERTICAL MODE switch positions notice that the display is again stable in ai positions as in the previous step and that the LEFT VERT pushbutton is illuminated Set the A TRIGGER SOURCE switch to RIGHT VERT Sequentially select all of the VERTICAL MODE switch positions and notice that a stable display cannot be obtained in any position this is because there is no input signal connected to the right vertical unit and that the RIGHT VERT pushbutton is illuminated Return the A TRIGGER SOURCE switch to VERT MODE and notice that it is illuminated 33 34 Operating Instructions 7904A The B TRIGGER SOURCE switch operates similar to the A TRIGGER SOURCE switch when the B time base unit is selected to provide the display Set the TRIGGER SOURCE switch to VERT MODE and the VERTICA
385. h positions and notice the and B INTENSITY indicator lights these lights indicate which intensity control is active Set the CONTROL ILLUMINATION switch to the MEDIUM position Observe that the selected intensity indicator light and the lighted pushbutton switches on the 7904A and plug in units are dimmed Set the CONTROL ILLUMINATION switch to OFF and notice that the selected intensity indicator and pushbutton switches are extinguished Set the rear panel CONTROL ILLUMINATION switch to the HIGH position Return the HORIZONTAL MODE switch to A VERTICAL DEFLECTION SYSTEM 15 16 17 18 19 20 2 6 Connect the 4 V CALIBRATOR output to the input connectors of both amplifier units with two 42 inch coaxial cables and a bnc T connector Set the deflection factor of the left amplifier unit to display about 2 divisions of signal on the crt Notice that the position control of only the left amplifier unit affects the vertical position of the displayed trace Position the trace to the upper half of the graticule Set the VERTICAL MODE switch to RIGHT Set the deflection factor of the right amplifier unit to display about 2 divisions of signal on the crt Notice that the position control of only the right amplifier unit affects the vertical position of the displayed trace Position the trace to the lower half of the graticule Set the VERTICAL MODE switch to ALT Two traces should be displayed on the crt The top tr
386. hannel originating the word see Fig 3 8 The character positioning current or decimal positioning current generated by the Hori zontal Character Position Counter or Decimal Point Logic stages is added to the X horizontal signal at the input to the X Output Amplifier providing horizontal positioning of the characters within each word The Word Trigger stage produces a trigger from the End of Word pulse generated by the Time Slot Counter stage after the tenth time slot This Word Trigger pulse advances the Channel Counter to display the information from the next channel or plug in This Word Trigger stage can also be ad vanced to jump a compiete word or a portion of a word when a Jump Command is received from the Row Data Switch stage TIMER The Timer stage produces the timing sequence for all cir cuits within the Readout System This stage produces six time related output waveforms see Fig 3 11 The triangle waveform produced at pin 6 forms the basis for the remain ing signals The basic period of this triangle waveform is about 250 microseconds as controlled by RC network R2135 and C2135 The triangle waveform is clipped and amplified by U2126 to form the trapezoidal output signal at pin 10 The amplitude of this output signal is exactly 15 volts as determined by U2126 exact amplitude is neces sary to accurately encode data in plug in units see Encod ing the Data The trigger output at pin 5 provides the switching signa
387. he plug in The latter stage counts the number of characters generated and produces an output current to step the dis play one character position to the right for each character In addition the character position is advanced once during each of time slots 1 2 and 3 whether a character is gener ated during these time slots or not This action fixes the starting point of the standard format display such that the first digit of the scaling factor always starts at the same point within each word regardless of the information en coded in time slot 1 2 or 3 preceding this digit Also by encoding row 10 and column 0 during any time slot a blank space can be added to the display Decimal points can be added to the display at any time by addressing the appropri REV NOV 1985 Theory of Operation 7904A ate row and column See Character Selection Matrix for lo cation of decimai points The Horizontal Character Position Counter stage is reset after each word by the Word Trigger pulse The Character Generators binary output is shaped by the X and Y Vector Generators into the appropriate X and Y Axis signals to create characters The Vector Amplifier outputs are amplified by the X and Y Output Amplifiers for use by the instruments horizontal and vertical deflection systems The Channel Counter output is also used by these stages so the display from each channel is positioned to the area of the CRT which is associated with the plug in and c
388. he Z AXIS INPUT to provide intensity modulation for the display This type of raster display could be used to provide a television type display Complete information on operation using the Z axis feature is given under Intensity Modulation Operating instructions 7904A To provide a stable raster display both time base units must be correctly triggered Internal triggering is not provided for the time base units when they are in the vertical compartments external triggering must be used Also blanking is not provided from the time base units when they are installed in a vertical compartment 2 19 WARNING THE FOLLOWING SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY TO AVOID PERSONAL INJURY DO NOT PERFORM ANY SERVICING OTHER THAN THAT CONTAINED OPERATING INSTRUCTIONS UNLESS YOU ARE QUALIFIED TO DO 50 REFER TO OPERATORS SAFETY SUMMARY AND SERVICE SAFETY SUMMARY PRIOR TO PERFORMING ANY SERVICE 7904 instruction SERVICING SAFETY SUMMARY FOR QUALIFIED SERVICE PERSONNEL ONLY Refer to the Operators Safety Summary DO NOT SERVICE ALONE Do not perform internal service or adjustment of this product unless another person capable of rendering first aid and resuscitation is present USE CARE WHEN SERVICING WITH POWER ON Dangerous voltages exist at several points in this product To avoid personal injury do not touch exposed connections and components while power is on Disconnect powe
389. he line voltage For 230 volt operation CR15 is connected as a bridge rectifier and the voitage across C16 and C17 will be the approximate peak value of the line voltage Thus the dc voltage applied to the Inverter stage s about the same for either 115 or 230 voit operation Thermistors RT9 and RT13 limit the surge current when the power is first turned on After the instrument 25 kHz HV DRIVE i LOW VOLTAGE RECTIFIERS fOVER VOLTAGE STOP 046 043 SEMI REGULATED VOLTAGES TO LOW VOLTAGE REGULATORS PHASE SENSE FEEDBACK I REFERENCE Figure 3 23 Detailed block diagram of the Converter Rectifiers circuit ADD NOV 1985 3 59 7904 is in operation the resistance of the thermistors decreases so that they have little effect on the circuit When the instrument is turned off the Inverter Control stage turns off the Inverter which prevents it from discharging C16 and C17 C16 and C17 discharge slowly through R21 to allow for thermistor thermai recovery time This ensures sufficient thermistor resistance to limit the turn on surge current to a safe level Since C16 and C17 discharge slowly dangerous potentials exist within the power supply for several minutes after the POWER switch is turned OFF The presence of voltage in the circuit is indicated by the relaxation oscillator R19 C19 and DS19 Neon bulb 0519 will blink until the potential across C16 and C17 drops to
390. he overall system depend mainly upon the plug in units selected for use with this instrument Specific applications for the individual plug in units are described in the plug in unit instruction manuals The overall system can also be used for many applications which are not described in detail either in this manual or in the manuals for the individual plug in units Contact your Tektronix Field Office or representative for assistance in making specific measurements with this instrument VERTICAL AMPLIFIER PLUG IN UNITS 7A series plug in units except the 7A21N unit can be used with the 7904A Bandwidth and sensitivity ranges should be taken into consideration when selecting amplifier plug in units Singie Trace Any single channel amplifier will display a signal with the sweep provided by any 7B series time base plug in unit This combination leaves two unused compartments available for other special purpose units Blank plug in panels are available for any unfilled plug in compartment to reduce electromagnetic interference Dual Trace A dual channel amplifier in either vertical compartment can display two separate signals with the other vertical compartment free for other uses 2 15 Operating Instructions 7904A Three Trace dual channel amplifier can be used with any single channel amplifier to display three separate signals 1 two time base plug in units are used in the horizontal compartments two signals can
391. he sweep rate of the A HORIZ time base unit delaying sweep and then at the sweep rate of the B HORIZ time base unit delayed sweep The vertical display then shifts to the RIGHT VERT unit and its signal is displayed consecutively at the delaying and delayed sweep rates Chopped Mode The CHOP position of the VERTICAL MODE switch produces a display which is electronically Switched between channels at about a one megahertz rate general the CHOP mode provides the best display at sweep rates slower than about 20 milliseconds division or whenever dual trace single shot phenomena are to be displayed At faster sweep rates the chopped switching becomes apparent and may interfere with the display When the A or B TRIGGER SOURCE switches are set to VERT MODE the time base units are triggered from the left vertical plug in trigger signal The LEFT VERT or RIGHT VERT trigger source positions provide trigger signals to the time base units from the selected vertical unit only The trigger source is indicated by the illuminated trigger source pushbuttons This allows two time related signals to be displayed showing true time relationship If the signals are not time related the 2 12 display from the channel that is not providing the trigger signal will appear unstable The CHOP mode can be used to compare two single shot transient or random signals that occur within the time interval determined by the time base unit ten times sele
392. hin the graticule area Varies with plug in unit selected See 7904A Oscilloscope Vertical System Specification Table 1 7 3 dB down at 500 MHz 700 ps or less At least 160 1 from dc to 100 MHz and at least 80 1 from 100 MHz to 500 MHz Permits viewing the leading edge of triggering signal 100 ps or less Selected by front panel VERTICAL MODE Switch t TTA a aa e e e TT iM Left Vertical unit displayed Display alternates between Left and Right Vertical units at rate determined by Horizontal plug in unit s Display is algebraic sum of Left and Right Vertical units Display chops between Left and Right Vertical units asynchronously to Horizontal plug in unit s Right Vertical unit displayed General information 7904A TABLE 1 3 CONT Electrical Characteristics Characteristics Performance Requirements VERTICAL SYSTEM CONT Vertical Display Modes cont SLAVED ALT Slaved operation occurs if 1 VERT MODE switch is set to ALT 2 HORIZ MODE switch is set to ALT or CHOP 3 Time base unit is installed in each Horizontal compartment and 4 Time base unit installed in HORIZ compartment operates in slaved mode When in slaved ait operation the display alternates between 1 the trace produced by the LEFT VERT unit displayed at the sweep rate of B time base unit and 2 the trace produced by the RIGHT VERT unit displayed at the sweep rate of the time base unit NOTE
393. horizontal position of the displayed trace Position the start of the trace to the left graticule line with the B time base unit Position control Set the B time base unit Triggering controls for a stable display Set the HORIZONTAL MODE switch to ALT Two traces should be presented on the crt If the traces so overlap adjust the VERT TRACE SEPARATION B contro to position one trace to the bottom of the graticule area Turn the sweep rate switches of both time base units throughout their ranges Observe that each time base unit controls one of the traces independently of the other time base unit Also notice that when one of the time base units is set to a slow sweep rate below about 50 milliseconds division sweep alternation is evident only 1 of the traces is presented on the crt at a time Set the sweep rates of both time base units to 0 5 milliseconds division Rotate the A INTENSITY control notice that the intensity of the trace produced by the A time base unit changes Likewise the INTENSITY control changes the intensity of the trace produced by the time base unit only Return both intensity controls to desirable levels Set the HORIZONTAL MODE switch to CHOP Two traces should be displayed on the crt in a manner similar to that of the ALT display Turn the sweep rate switches of both time base units throughout their ranges A dual trace display will be presented at all sweep rates Set the VERTICAL MODE switch
394. ial Assembly No Effective Dscont Replaceable Electrical Parts 7904A Name amp Description RES FXD CMPSN 10 5 0 125 RES FXD FILM 2 61K OHM 17 0 125W 0 RES FXO FILM 287 OHM 125 0 5W TC TO RES FILM 909 OHM 125 0 125W TC T2 RES FILM 1 43K 1 0 125W TC TO RES FXD FILM 1 43K OHM 12 0 125W TC TO RES FXO FILM 806 12 0 125W TC T0 RES FXD FILM 2 61K OHM 17 0 125W 0 RES FXD FILM 604 OHM 125 0 125W TC TO RES FILM 150 1 0 125 TC TO RES FXD FILM 332 OHM 1 0 25W TC TO RES FXD FILM 332 OHM 1 0 25W TC TO RES FXD FILM 1 2K OHM 5 0 25W RES FXD FILM 1 50K OHM 1 0 125W 0 RES FXO FILM 280 OHM 125 0 125W TC T0 RES FXD FILM 1 74K OHM 15 0 254 TC T0 RES FXD FILM 1 21K OHM 175 0 254 TC TO RES FXD FILM 16 2K OHM 125 0 125W TC TO RES FXD FILM 464 OHM 1 0 125W TC TO RES FXD FILM 107 OHM 125 0 125W TC T0 RES FXD FTLM 62K 5 0 25 RES FXD FILM 470 OHM 5X 0 25W RES FXD FILM 4 3K OHM 5 0 25W RES FXO FILM 28 0 OHM 125 0 125W TC TO RES FXO FILM 28 0 OHM 1 0 125W TC TO RES FXD FILM 12 7 1 0 125W TC TO RES FXO FILM 15 0K OHM 1 0 125W TC T0 RES FXD FILM 15 0K OHM 1 0 125W TC TO RES FILM 15 0 OHM 15 0 1258 TC TO RES FXD FILM 61 9K OHM 17 0 1259 TC TO RES FXD FILM 453 OHM 175 0 1
395. ical Amplifier Board to position the two rows of readout characters to the middle of the top and bottom divisions of the graticule Set Character Height adjustment R2273 on the A15 Readout System Board as desired g EXAMINE display for two rows of zeros 40 zeros to each row with no character overlap Total length of each row of characters is between 9 5 and 10 divisions h ADJUST HO Ctr adjustment R114 and RO Gain adjustment R101 on the A28 Horizontal Amplifier Board to horizontally center the zeros display and to set the length of each row of characters to between 9 5 and 10 divisions i Set the POWER switch to OFF and replace Q2225 in its socket 5 70 G3 ADJUST CHARACTER SCAN A15R2128 NOTE If the preceding step was not performed first perform step G1 then proceed G3 SETUP CONDITIONS 7904A Controls VERTICAL MODE tc 9c a5 a Test Equipment Controls Amplifier Unit Deflection Factors Display Mode 50 mV div Dual trace 4593 546 a EXAMINE the displayed characters for completeness without overscanning overscanning causes a bright dot where traces overlap b ADJUST Character Scan adjustment R2128 the 15 Readout System Board for fully scanned characters without overscanning The m and the 5 will show the most change G4 ADJUST COLUMN AND ROW MATCH A15R2214 A15R2183 NOTE If the preceding step was not performed first perform ste
396. ied service personnel 4 Nothing capabie of generating or holding a static charge should be allowed on the work station surface 5 Keep the component leads shorted together whenever possible 6 Pick up components by the body never by the leads 7 Do not slide the components over any surface 8 Avoid handling components in areas that have a floor or work surface covering capable of generating a static charge 9 Use a soidering iron that is connected to earth ground 10 Use only special antistatic vacuum type desoldering tools such as the Pace model 10 MULTI PIN CONNECTORS Pin 1 on multi pin connectors is designated with a triangle A triangle dot or square printed on circuit 4 6 boards denotes pin 1 When a connection is made to a circuit board the orientation of the triangle on the multi pin holder is determined by the index triangle dot or square printed on the circuit board see Fig 4 3 Some multi pin connectors are keyed with a plastic pin that protrudes through a hole on the circuit board Proper mating with the multi pin connector and the pin s on the circuit board cannot be accomplished unless this pin is aligned with the hole on the circuit board Some multi pin connectors are equipped with a locking mechanism to more readily secure the connector to the circuit board To remove these connectors grasp the connector body and pull perpendicular to the circuit board They should not be remove
397. ific encoding data and circuitry is shown in the individ ual plug in unit manuals COLUMN AND ROW DATA SWITCHES The encoding data from the plug in units is connected to the Column and Row Data Switch stages A column data line and a row data line convey analog data from each of the 8 data sources 2 channels from each of the 4 plug in compartments The Column Data Switch U2190 and the Row Data Switch U2180 receive the Channel Address Code from the Channel Counter This binary code directs the Column Data Switch and the Row Data Switch to the channel which should be the source of the encoding data Table 3 13 gives the eight combinations of the Channel Address Code and the resul tant channel selected with each combination These stages have nine inputs and provide a time multiplexed output at pin 7 which includes the information from of the input channels Eight of the nine inputs to each stage originate in the plug in units and tne ninth input to U2190 comes from a special data encoding network composed of resistors R2191 through R2199 See Zeros Logic and Memory de scription for further information on ninth channel In addition to the encoding data inputs from the plug in units inputs are provided to the Column Data Switch from the VERTICAL MODE and HORIZONTAL MODE switches to inhibit the readout for any plug in unit s not selected for display When a unit is not selected the line corresponding to the opposite channel is HI t
398. ignals In either the LEFT VERT or RIGHT positions of the TRIGGER SOURCE switches the two signals are displayed showing true time relationship However if the signals are not time related the display from the plug in that is not providing a trigger signal will be unstable on the crt The trigger source switches are illuminated indicating the source of the trigger signal When the ALT VERTICAL MODE switch is selected and either the ALT or CHOP button of the HORIZONTAL MODE switch is selected the instrument operates in the slaved alternate mode Under this condition the signal from the LEFT VERT unit is always displayed at the sweep rate of the B HORIZ time base unit and the signal from the RIGHT VERT unit is displayed at the sweep rate of the A HORIZ time base unit nondelayed sweep only This resuits in two displays that are completely independent as to vertical deflection and sweep rate This display is equivalent to the display obtainable with a dual beam oscilloscope for most repetitive display combinations In slaved alternate mode with the and B TRIGGER SOURCE switches set to VERT MODE the A time base unit receives a trigger from the right vertical and the B time base unit receives a trigger from the left vertical This is indicated by the illuminated 7904A Trigger Source buttons If a delayed sweep operation is used with this mode a different sequence is displayed First the LEFT VERT unit signal is displayed at t
399. igned for general purpose applications The 7904A accepts four 7000 series plug in units to form a highly flexible oscilloscope system The left pair of plug in compartments for vertical deflection and the right pair of plug in compartments are for horizontal deflection Electronic switching between each deflection system allows duai trace vertical and dual sweep horizontal displays The 7904A features include an 8 cm x 10 cm crt display area with a crt readout display of alphanumeric characters from the associated plug in units The readout display includes deflection factor sweep rate and other encoded parameters The above delayed sweep display was obtained using 7B92A Dual Time Base 11 megahertz sine wave signal was applied simultaneously to the 7A29 Input and to the 7D15 Freq In connectors The input frequency is monitored and continuously updated on the 7904A crt readout display The 7A26 Dual Trace Amplifier provides additional vertical display capabilities when selected viii Section 1 7904A GENERAL INFORMATION This section is the first place to look for information on your 7904A Oscilloscope First we describe the features of the 7904A and the basic content of the instruction manual Next we describe installation power source and power cord requirements operating temperature considerations instrument repair services and packaging for shipment instructions We also include the electrical environmental and
400. ime Slot Counter When this pin is held LO the Time Siot Counter resets to time slot 1 The Time Slot Counter can be reset in this manner only when a Jump Command is received by U2155C and D see following discussion WORD TRIGGER The Word Trigger stage is made up of U2155A and B Quiescently pin 3 of U2155A is LO as established by the operating conditions of U2155D and C Therefore the LO end of word pulse produced by the Time Slot Counter results in a level at pin 1 of U2155A This level inverted by U2155B provides negative going Word Trigger pulse to the Channel Counter Also a Word Trigger pulse is produced by U2155B when a Jump Command is received at pin 8 of U2155C This condition can occur during any time siot see Row Decoder for further information on origin of the Jump Command integrated circuit 021550 and are connected as a bistable flip flop The positive going Jump Command at pin 8 of U2155C produces a LO at pin 10 This LO is inverted by U2155D to produce a HI at pin 13 which allows 9 to be pulled through CR2156 The flip flop has now been set and remains this condition until reset even though the Jump Command at pin 8 returns to its LO level The output level at pin 13 turns Q2158 to pull pin 16 of the Time REV NOV 1985 Theory of Operation 7904A 1195 32 4593 62 TIME SLOT PULSE 1 PIN 3 TIME SLOT PULSE 2 PIN 13 TIME SLOT PULSE 3 12
401. ime base unit NOTE The VERT TRACE SEP B control is inoperative in Slaved alternate mode NENNEN the RIGHT VERT unit displayed at the sweep rate of the A i 6 Check Vertical Display Modes F10 Check Vertical Display Modes tesis Positions B trace at least 4 div above and below A trace when 7904A operates in ALT or CHOP horizontal modes See note above concerning Selected by front panei switches Lights behind the pushbuttons are illuminated to indicate the trigger Source E7 Check Vertical Trace Separation B Operation F11 Check Vertical Trace Separation B Operation TRIGGERING The trigger source is controlled by the Vert Display Mode selection The source is shown by the illumination of the LEFT and RIGHT trigger source buttons The source follows is same as the Vert Display with the following two exceptions VERT TRIGGER MODE SOURCE CHOP LEFT RIGHT for SLAVED A TRIG ALTERNATE LEFT for B TRIG See Vertical Display Modes under VERTICAL SYSTEM in this table for slaved alternate operation Trigger source LEFT vertical unit LEFT trigger source button illuminated C3 Check Trigger Selector D5 Check Trigger Selector Operation Operation Checks and Adjustment 7904A TABLE 5 2
402. imum Input Voltage Maximum Repetition Rate ARRIERE LINE VOLTAGE SELECTOR Selects 115 V or 230 range POWER SOURCE Selected by rear panel LINE Does not normaily require customer verification VOLTAGE SELECTOR switch Satisfactory operation is substantiated at the factory VOLTAGE RANGE AC RMS 115 V Rated From 90 V to 132 V 230 V Rated From 180 V to 250 V Line Frequency Power Consumption 210 W nominal From 48 Hz to 440 Hz 5 10 Checks and Adjustment 7904A TABLE 5 2 CONT Performance Check Summary Requirements Maximum Current 3 5 A at 60 Hz 90 V Line 1 8 A at 60 Hz 180 V Line 4 A Fast Blow ADJUSTMENT INTERVAL To maintain instrument accuracy check performance every 2000 hours of operation or annually if used infrequently Before compiete adjustment thoroughly clean and inspect this instrument as outlined in the Maintenance section TEKTRONIX FIELD SERVICE Tektronix Field Service Centers and the Factory Service Center provide instrument repair and adjustment services Contact your Tektronix Field Office or representative for further information TEST EQUIPMENT REQUIRED The test equipment listed in Table 5 3 is required for a complete Adjustment and Performance Check of the instrument if only a Performance
403. in U2232 is interrogated If information was stored in this memory a positive going output is produced at pin 7 This pulse is connected to pin 10 of the Column Decoder through Q2240 to add one unit of current at the input of the Column Decoder This produces a zero after the character displayed during time slot 4 During time slot 6 another memory within U2232 is interrogated to see if 3 34 another zero should be added if another zero is necessary a second positive output is produced at pin 7 which again results in a column 1 output from the Column Decoder and a second 0 in the crt display Finally another memory within U2232 is interrogated during time slot 8 to determine whether the prefix should be changed or left at the value that was encoded If data has been encoded that calis for a shift in prefix a negative going output level is produced at pin 7 This negative level subtracts one unit of column current from the data at the input to the Column Decoder Notice on the Character Selection Matrix of Figure 3 9 that when row 4 is programmed a reduction of one column resuits in a one column shift of the prefix For example with the 100 uV program shown in Figure 3 16 if the data received from the plug in called for a shift in prefix the crt readout would be changed to 1 mV zeros deleted by program see Encoding the Data The 100 microamperes of quiescent current through H2213 provided by Q2240 see Display Skip Generator
404. in less than 1 ys triggers the Readout to display one complete readout frame and illuminates the graticule for approximately 0 5 s ou to 15 V open collector TTL source Probe Power Two power connectors on rear panei Pin 1 5 V 46 2 Chassis ground Pin 3 15 V dc m D Ha BR _ m X M Pin 4 15 V dc 1 8 General Information 7904A TABLE 1 3 CONT Electrical Characteristics Characteristics Performance Requirements REMOTE CONNECTORS AND SWITCHES CONT Z AXIS INPUT Externat Bnc connector on rear panel Polarity and Sensitivity Positive 2 V provides compiete blanking from maximum intensity condition Negative 2 V provides complete from minimum intensity condition Low Frequency Limit Dc Input Resistance Approximately 470 Q input Capacitance Less than 50 pF Open Circuit Voltage Approximately 0 V Maximum Input Voltage 15 V dc plus peak ac Maximum Repetition Rate 1 MHz LINE VOLTAGE SELECTOR Selects 115 V or 230 V range POWER SOURCE _____ VOLTAGE RANGE AC RMS Selected by LINE VOLTAGE SELECTOR switch eomSOVtot3V OOO 230 V Rated mum Line Frequency From 48 Hz to 440 Hz Power Consumption Maximum Current 210 W nominal 8 5 A at 60 Hz 90 V Line 1 8 A at 60 Hz 180 V Line Fuse 4 A Fast Bl
405. in up to 10 char acters aithough the typical display will contain between 2 and 7 characters per word The characters are selected from the Character Selection Matrix shown in Figure 3 20 In addition 18 operational addresses are provided for spe cial instructions to the Readout System The unused loca tions in the Matrix shaded area are available for future expansion of the Readout System The method of address ing the locations in the Character selection Matrix is de scribed in the following discussion DEVELOPING THE DISPLAY This description is intended to relate the basic function of each stage to the operation of the overall Readout System Detailed information on circuit operation is given later The key block in the Readout System is the Timer Stage see schematic This stage produces the basic signals that establish the timing sequences within the Readout System The period of the timing signal is about 250 microseconds it drops to about 210 microseconds when Display Skip is re ceived see detailed description of Timer stage for further information This stage also produces control signals for other stages within this circuit and inhibit signals to the Ver tical Amplifier Horizontal Amplifier and Logic circuits which aliow a readout display to be presented The Time Siot Counter stage receives a trapezoidal voltage signal from the Timer stage and directs it to one of ten output lines These output lines are labeled TS
406. ing components or plug in units The exploded view drawings associated with the Replaceable Mechanical Parts list located at the rear of this manual may be helpful in the removal or disassembly of individual components or sub assemblies DISPLAY UNIT KICKSTAND The Display unit of the 7904A Oscilloscope mainframe is equipped with a kickstand to ease access to interior components of the instrument see Fig 4 10 To use the kickstand feature disconnect the power cord plug from the power source Then remove the side and top panels as described under Cabinet Panel Removal Remove the two screws on each side of the 7904A which connect the two units This will allow the upper portion of the frame coupling to be pivoted outward The two units can now be separated at the front of the instrument the kickstand will hold the units apart To assemble the units disengage the kickstand and reverse the disassembly procedure POWER SUPPLY UNIT REMOVAL The power supply unit can be slid out of the rear of the 7904A to gain better access to the A13 Logic board Ai4 Trigger Selector board or for power supply maintenance and troubleshooting To remove the power supply unit from the mainframe first remove the four screws which hold the power supply unit to the rear frame of the instrument see Fig 4 11 Slide the power supply unit out of the mainframe until it can be set down on the work surface be sure to guide the interconnecting cables so
407. inputs A good rule is not to apply a signal of more than about eight times the vertical deflection factor Larger voltages may result in a distorted dispiay 3 To ensure the greatest dynamic range in the ADD mode set the position controls of the plug in units to a setting which would result in a mid screen display if viewed in the LEFT or RIGHT positions of the VERTICAL MODE switch 4 For familiar response from each channel use identical plug ins and set the plug in units for the same type of input coupling mode Horizontal Modes When either the A or B button of the HORIZONTAL MODE switch is pressed the signal is displayed at the sweep rate of the selected time base unit Set the applicable INTENSITY control and trigger source switch for the desired display Alternate Mode The ALT position of the HORIZONTAL MODE switch provides crt sweeps derived alternately from the two time base units Although the ALT horizontal mode can be used at sweep rates the CHOP mode provides a more satisfactory display at sweep rates slower than about 20 milliseconds division At slower sweep rates the switching between the alternate mode traces becomes apparent and may interfere with correct analysis of the display NOTE This instrument will not operate in the ALT position of the HORIZONTAL MODE switch if either horizontal plug in compartment is vacant The A and B INTENSITY controls allow individual adjustment of the traces produced by
408. ion from the electrical specifications These procedures also verify that the controls function properly This section is divided into two parts Part Performance Check is provided for those who wish to verify that this instrument meets the applicable electrical specifications in section 1 without making internal adjustments Part H Adjustment and Performance Check provides a procedure that includes adjustments and performance checks in addition to verifying that the controls function properly The procedures in Part 1 and Part are written so that the entire instrument or any major circuit or part of a circuit can be checked or adjusted Table 5 1 Checks and Adjustment Procedure Electives lists the choices available and instructions for performing either complete or partial procedures Also refer to page 5 2 Using These Procedures for more detailed information TABLE 5 1 Checks and Adjustment Procedure Electives Electives Procedure Functional Check Perform Power Up Sequence in Part lI Adjustment and Performance Check Then proceed sequentially through subsections B C etc to end If a functional check only is desired perform the Operators Checkout Procedure in Section 2 Perform Power Up Sequence in Part I Performance Check Then proceed sequentially through subsections A B C etc to end Performance Check Only Complete Check and Adjustment Part 11 Perform Power Up Sequence in
409. is basicaily the same as described for the previous supply regulators Error voltage is provided through R131 to pin 2 of U114A and pin 3 is referenced to the 50 VS sense line The divider ratio of R113 and R114 is 10 1 so pin 3 of U114A is at 5 volts when the supply is operating normally The level on the 50 V Sense line is held stable by the 50 volt supply Therefore any change at the output of the 5 volt supply appears at pin 2 of U114A as an error signal The output voltage is regulated in the manner described previously for the 50 voit supply Diode CR132 limits the output of this supply to about 0 6 voit if it is shorted to one of the negative supplies The 5 volt current limiting accomplished by U114B protects this supply from excessive output current damage With normal supply current through R133 and R134 the voltage drop across this parallel resistance biases Q118 on If the current through R133 and R134 increases above a safe level pin 7 of U114B reduces the forward bias current to Q118 Now the base current of Q122 is reduced which decreases the voltage on the base of Q126 This limits the conduction of Q126 to a safe current level 15 V REGULATOR The 15 V Regulator regulates in the same manner as the 50 voit supply current limiting operates in the manner described for the 5 volt supply Error feedback 3 64 voltage to pin 2 of U64A is provided through R69 Pin 3 of U64A is referenced to the 50 VS se
410. is triggered on the 10 kHz waveform set the time base Triggering Level controis for triggered sweeps Checks and 7904 Part lI Adjustment and Performance Check E HORIZONTAL SYSTEM 2 3 Amplifier two required 4 Time Base 6 Low Frequency Sine Wave Generator 10 Signal Standardizer it Time Mark Generator E1 HORIZONTAL SYSTEM PRELIMINARY SETUP a Perform the Adjustment and Performance Check Power Up Sequence b Refer to Section 6 Instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure c See the foidout page in Section 8 Diagrams and Circuit Board lliustrations d Set the 7904A controls as follows POWER TE On VERTICAL RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE A INTENSITY dede at e Midrange HORIZONTAL MODE A B INTENSITY eei cedex ehe Midrange B TRIGGER SOURCE VERT MODE READOUT INTENSITY OFF in detent GRAT As desired CONTROL ILLUM MEDIUM rear panel CALIBRATOR 0 4 V 12 Coaxial Cable 18 inch 13 Coaxial Cable 42 inch 15 Adapter BNC T 17 Screwdriver Slotted E2 ADJUST HORIZONTAL AMPLIFIER LIMIT CENTERING A28R630 NOTE First perform step E1 then proceed E2 SETUP CONDITION
411. iscussion of the Right Channel Feedbeside is given The function of the Feedbeside stage is to compensate for low frequency imperfections in the frequency response of the Channel Switch stage 0668 Seif heating of the transistor base emitter junction in some transistors within U668 causes the low frequency gain to appear larger than the midband gain To correct this a portion of the input signal is picked off through R502 and R504 and applied to U508 This differential signal is converted to a single ended signal and distributed into four RC resistive capacitative networks each having a different time constant Variable Components R512 R515 R520 R525 R530 and C538 are adjusted to provide an accumulated waveform This waveform is converted to a paraphase signal by 0538 Q542 and Q548 and is then injected into U668 through Pins 6 and 4 where it is subtracted from the signal entering 1668 at pins 7 and 9 Proper adjustment results in flat frequency response and optimum transient response at the output pins 3 and 13 ADD NOV 1985 Theory of Operation 7904A VERTICAL AMPLIFIER A schematic diagram of the Vertical Amplifier is given on Diagram 9 in Section 8 of this manua Diagrams and Circuit Board lHustrations The schematic is divided by gray shaded lines separating the circuitry into major stages These stages aid in locating components mentioned here Sub headings in the following discussion use the stage names to fu
412. isplay Set the test oscilloscope vertical deflection factors to display 2 divisions of CALIBRATOR signal and 1 division of time marker signal Set the test oscilloscope Vertical Mode to Add Set the test oscilioscope sweep rate to 0 2 second division CHECK that the time required for the 1 millisecond time marks to drift from the positive level of the CALIBRATOR signal to the negative level and back to the positive level is more than 0 4 second 2 divisions This time can be measured directly from the display by observing the number of divisions that the markers move across the display area before it returns to the positive level 5 17 Checks and Adjustment 7904A Part i Performance Check B4 CHECK CALIBRATOR RISE TIME FALL TIME AND DUTY CYCLE NOTE if the preceding step was not performed first perform step B1 then proceed B4 SETUP CONDITIONS 7904A Controls No change in settings CALIBRATOR Test Equipment Controls Test Oscilloscope Sweep Rate 0 1 us div Triggering Auto AC internaj 4593 413 a Connect the CALIBRATOR output to the inverting vertical input of the test oscilloscope b Set the test oscilloscope vertical deflection to display 4 divisions of CALIBRATOR signal C Set the test oscilloscope for a stable display triggered on the positive transition of the CALIBRATOR signal 5 18 CHECK the displayed waveform for more than 5 divisions horizontally between
413. ively These stages take the analog current from the 8 data lines 2 channels from each of the 4 plug in compartments and produce a time multiplexed analog voltage output containing ail of the column and row information from the plug ins The Column Data Switch and Row Data Switch are sequenced by the binary Channel Address Code from the Channel Counter The time multiplexed output of the Column Data Switch is monitored by the Display Skip Generator to determine if it represents valid information that should 3 25 Theory of Operation 7904A be displayed Whenever information is not encoded in a time slot the Display Skip Generator produces output level to prevent the Timer stage from producing the control signals that normally interrupt the crt display and present a character The analog outputs of the Column Data Switch and Row Data Switch are connected to the Column Decoder and Row Decoder stages respectively These stages sense the magnitude of the voltage input and produce an output current on one of ten lines The outputs of the Column Decoder stage are identified as C 1 through C 10 column 1 through 10 corresponding to the encoded column information Likewise the outputs of the Row Decoder stage are identified as R 1 through R 10 row 1 through 10 corresponding to the encoded row information The primary function of the row and column outputs is to select a character from the Character Selection Matrix t
414. iven in Table 5 7 5 65 Checks and Adjustment 7904A Part H Adjustment and Performance Check F8 CHECK VERTICAL AMPLIFIER 500 MHz GAIN NOTE If the preceding step was not performed first perform step F1 then proceed F8 SETUP CONDITIONS 7904A Controls VERTICAL MODE High Frequency Sine Wave Generator 5 2 8 53 s 0 Time Base Aux in CW In 2X Attenuator and Input 50504 Output Head Test Equipment Controls Time Base Sweep 0 1 ms div Triggering Auto AC External Signal Standardizer Vert or Horiz Freq Resp High Frequency Sine Wave Generator Reference Frequency a Set the signal standardizer Amplitude control fully clockwise b Set the high frequency sine wave generator for a 10 division display at the reference frequency between 6 and 50 megahertz centered on the graticule obtain a 10 division display first obtain an eight division display then vertically position the display one division down and increase the output amplitude of the sine wave generator so that the top of the display reaches the top of the graticule 5 66 Set the signal standardizer Amplitude control for a six division display centered on the graticule The CW Leveled indicator should be lit Without changing the output amplitude increase the generator frequency until the displayed amplitude is reduced to 4 6 divisions If the CW Leve
415. izer Vert or Horiz Step Resp 100 kHz 4593 539 a Set the signal standardizer Amplitude control for a six division display b Set the time base Triggering and Position controls for a stable display c EXAMINE displayed pulse for optimum flat top within 0 06 division with the signal standardizer Rep Rate and time base sweep rates given in Table 5 6A d ADJUST compensation adjustments on the A16 Vertical Channel Switch Board as given in Tabie 5 6A for optimum flat top on the displayed waveform e Move the signal standardizer to the LEFT VERT compartment 5 64 TABLE 5 Right Channel Switch Compensation Signal Rep Rate vs Sweep Rate Signal Standardizer Rep Rate _ 100 kHz Adjustment Sweep Rate C538 R530 TABLE 5 6B Left Channel Switch Compensation Signal Rep Rate vs Sweep Rate Signal Adjustment Standardizer Sweep Rate C638 R630 R625 R612 1 10 Hz 20 0 ms Set the VERTICAL MODE switch to LEFT VERT Set the signa standardizer Rep Rate to 100 kHz and the time base unit sweep rate to 2 us division Set the Amplitude and Position controls for a six division display centered on the graticule area EXAMINE dispiayed pulse for optimum flat top within 0 06 division with the signal standardizer Rep Rate and the time base unit sweep rates given in Table 5 6B ADJUST compensation adjustments on the A16 Vertical Channel Switch Board
416. l controls and for familiarization with the instrument Only instrument functions not measurement quantities or specifications are checked in the procedure therefore a minimum amount of test equipment 15 required If performing the Operators Checkout Procedure reveals improper performance or instrument malfunction check the operation of associated equipment then refer to qualified service personnel for repair or adjustment of the instrument TEST EQUIPMENT REQUIRED The following test equipment was used in preparing the Operators Checkout Procedure Other test equipment which meets these requirements may be substituted When other equipment is substituted the control settings or setup may need to be altered 2 1 Operating Instructions 7904A Tektronix 7904 OSCILLOSCOPE iNTENSITY SIG QUT TRIGGER B id soo ZA VERTICAL MODE ems ERT e VERE 2 A A MORIZ RELAYING TYE an FORI 4593 22A Figure 2 1 Front panel controls connectors and indicators oO O X Oe 0 Camera Power Connector not labeled Three pin connector provides power for camera operation and receives single sweep reset signal BEAMFINDER Switch when pressed compresses and defocuses display within graticule area FOCUS Control optimizes crt trace definition B INTENSITY Indicator illumina
417. l for the Time Siot Counter 3 41 Theory of Operation 79044 VERTICAL HORIZONTAL READOUT MODE FROM OUTPUT PLUG IN SIGNALS CIRCUIT INTERFACE 2 TIME SLOT PULSES TO SLOT TIMER VERTICAL AND HORIZONTAL 10 COUNTER PLUG IN COMPARTMENTS 92128 SINGLE SHOT LOCKOUT DISPLAY SKIP SKIP iF DATA ENCODED IN 5 3 SINGLE SHOT LOCKOUT DISPLAY SKiP 2120 GENERATOR SKIP iF NO COLUMN DATA ENCODED IN THIS TIME SLOT FLIP FLOP U2162B Q2223 Q2229 END OF FRAME WORD TRIGGER U2127B CHANNEL COUNTER U2127A 8 TS 2 TO TS 9 IDENTIFY NETWORK COLUMN ANALOG DATA IN FROM PLUG IN COMPARTMENTS CHANNEL COUNTER CODE DATA ENCODED BY RESISTORS IN PLUG IN UNITS TIME MULTIPLEXED ANALOG VOLTAGES ROW DATA SWITCH ROW ANALOG DATA IN FROM PLUG 02180 i i i i i f i i i i i i i i i i IN COMPARTMENTS Figure 3 21 Detailed block diagram of the Readout System SN B031767 amp Above 3 42 REV NOV 1985 Theory of Operation 7904A STROBE 7 ENABLE ZEROS LOGIC AND MEMORY 92232 C 1 TO C 4 C 10 DECIMAL N ar POSITION WORD 92157 92251 GDENTIF Y OUTPUT AMPLIFIER COLUMN 4 COLUMN CHARACTER DE
418. l of the Auto Focus Channel Switch and Amplifier output diagram 12 through CR33 During the positive half cycle the focus grid voltage is clamped to the voltage set by the FOCUS contro 2005 diagram 2 and Focus Preset R55 through R37 CR37 and CR38 During the negative half cycle C39 charges through CR38 to establish the proper level at the focus grid electrode CRT CONTROL The ASTIG adjustment R2025 diagram 2 used in coniunction with the FOCUS controi R2005 diagram 2 to obtain a well defined display varies the voltage level on the astigmatism grid The SHIELD VOLTS adjustment R155 varies the positive potential on the grid shielding the vertical deflection plates from stray voltages existing within and near the crt GEOM adjustment R143 varies the positive level on the horizontal deflection plate shield to controi the overall geometry of the display Two adjustments control the trace alignment by varying the magnetic field around the crt The Y AXIS ALIGN adjustment R122 diagram 10 controis the current through L22 which affects the crt beam after vertical deflection but before horizontal deflection Therefore it affects only the vertical Y components of the display The TRACE ROTATION adjustment R2035 diagram 2 controis the current through 121 and affects both the vertical and horizontal rotation of the beam ADD NOV 1985 4 5 The Converter Rectifiers circuit provides
419. layed on the crt Any of the 50 characters shown on the Character Selection Matrix of Figure 3 9 can be addressed by proper selection of the column and row currents Only one character is addressable in any one time slot a space can be added into the displayed word by the Decimal Point Logic and Character Position Counter stage when encoded by the plug in The latter stage counts the number of characters generated and produces an output current to step the display one character position to the right for each character In addition the character position is advanced once during 3 26 TRIGGER PIN 5 t i CHARACTER i i 4 i SCAN PIN 16 SN B031766 i 3 f amp BELOW dne X Y INHIBIT COMMAND PIN 13 READOUT INTENSITY n m NOTE TEST OSCILLOSCOPE EXTERNALLY TRIGGERED FROM T2251 SN B031766 amp BELOW 02127 5 SN B031767 amp UP 1195 29 4593 59 Figure 3 11 Output waveforms of the Timer stage REV NOV 1985 each of time slots 1 2 and 3 whether character is generated during these time slots or not This action fixes the starting point of the standard format display such that the first digit of the scaling factor always starts at the same point within each word regardless of the information encoded in time slot 1 2 or 3 preceding this digit Also by encoding row 1
420. lder with tweezers and place in plastic frame slot being careful to match the flat contact holder with the flat frame corner Place a clean plastic envelope over finger and press with finger to seat contact holder into the frame The contact holder must be evenly seated on all four sides Flush HYPCON Match hybrid flat corner with board receptable flat corner and place hybrid in receptable Match pointed mounting ear of HYPCON connector with flat corner of receptacle and guide registration pins into the board hold Stepped HYPCON Using tweezers match the hybrid corner index with the elastomer contact holder index and insert between the registration pins Turn the assembly over grasp the hybrid hat with the tweezers and guide the registration pins into the board holes Match the plastic frame pointed mounting ear with the circuit board arrow insert mounting hardware and apply 2 inch pounds of torque to secure the connector assembly C 2316 238 2314 38 Figure 4 14 cont HYPCON assembly removal and replacement 4 25 Maintenance 7904A The cleaning process either hand cleaning with a solvent or machine cleaning in an automatic detergent wash is not recommended for boards containing Hypcon connectors if a component adjacent to a Hypcon connector must be replaced the following steps are recommended 1 Remove the hybrid IC and Hypcon connector see Disassembly and Hemoval instructions before any soldering or cleaning and s
421. le B Time Base Unit Sweep Rate 50 ns div Triggering Auto AC External Amplifier Position Off screen 4593 505 Connect the test oscilloscope 10X probe tip to TP186 located on the A21 Z Axis Board and the probe ground to chassis ground b With the test oscilloscope triggered on the rising edge of the signal use the test oscilloscope variable Gain and Position controls to obtain an 8 division display centered on the graticule Setthe 7904A B INTENSITY control for a 6 division display on the test oscilloscope Position the display to view the leading edge of the waveform at the center graticule lines d EXAMINE the test oscilloscope display for optimum square corner and flat top on the displayed pulse Aberrations should be less than 596 peak to peak 0 3 division ADJUST Comp 5 C180 for flat top and Comp 1 C150 Comp 2 R150 Comp 3 R155 and Comp 4 C155 located on the A21 Z Axis Board for optimum square corner of the displayed pulse use iow capacitance alignment tool to adjust variable capacitors 5 40 Set the INTENSITY control for 1 5 divisions of display on the test oscilloscope EXAMINE test oscilloscope display for less than 596 aberration 0 75 division ADJUST R150 and C150 located on the A21 Z Axis Board for optimum square corner at 1 5 divisions of displayed pulse Set the B INTENSITY control for a 6 division display on the test oscilloscope Set the test os
422. le lights except when in the PULSED position by controlling the output of the graticule light supply see LV Regulators diagram 15 Variable resistor R1902 GRAT ILLUM PRESET 3 51 Theory of Operation 7904A determines the brightness of the graticule lights when the GRAT ILLUM control is set to PULSED In the PULSED mode the graticule lights are gated on for approximately 0 5 second Programmable unijunction transistor Q1908 in conjunction with Q1910 generates the pulse to turn the graticule lights on A negative signal from the MAN pushbutton the Gate or from an external input wili cause Q1908 to conduct and start discharging C1908 At this time Q1910 turns off which allows R1902 to control the output of the graticule light supply Capacitor C1908 discharges until Q1908 cannot maintain conduction As Q1908 turns off C1908 begins to charge positive until the zener voltage of CR1910 is reached which turns on Q1910 its collector then goes negative to turn the graticule light supply off When in the PULSED mode and operating from the GATE source the graticule lights will turn on momentarily at the trailing edge of the Gate end of each sweep INTENSITY LIMITER The Intensity limiter stage limits the crt screen current to approximately 4 microamperes to prevent burning the crt phosphor by iong term on screen trace operation This limiting occurs when the limit output of the Anode Multiplier U21 diagram 13 produces a
423. led indicator extinguishes increase the amplitude of the sine wave generator signal until the light just turns on NOTE The signal standardizer CW Leveled light must be on and the sine wave generator must be properly connected for a valid check Refer to the signal standardizer and high frequency sine wave generator manuals CHECK sine wave generator frequency is 500 MHz or higher verifies 500 megahertz gain Move the signal standardizer to the LEFT VERT compartment leave signal connected and set the VERTICAL MODE switch to LEFT CHECK repeat parts d through f for the LEFT VERT compartment INTERACTION f the specifications of steps org were not met perform steps F2 F3 F4 F6 and F8 F9 CHECK VERTICAL CHANNEL ISOLATION NOTE If the preceding step was not performed first perform step F1 then proceed F9 SETUP CONDITIONS 7904A Controls VERTICAL MODE High Frequency Sine Wave Generator f a 9 x Coaxial Cable Test Equipment Controls Time Base Sweep Rate Triggering Amplifier input Coupling High Frequency Sine Wave Generator 4593 542 Connect the output of the high frequency sine wave generator to the amplifier input Set the output of the high frequency sine wave generator and the amplifier deflection factor for eight divisions of deflection at 500 MHz Set the VERTICAL MODE switch to LEFT Checks and Adjustment 7904A Part li Adjusim
424. lip catches and holds the switch in place C1967 3 Figure 4 17 Removal procedure for pushbutton switches mounted on the 5 Mode Switch board 4 29 Maintenance 7904A 8 Install the A12 Control Rectifier in the power supply unit as described under Circuit Boards in this section LINE FUSE The line fuse used in this instrument is located on the rear panel of the power supply unit Replace the line fuse F10 only with one of proper type and rating NOTE The line voltage fuse F10 is used for both 110 volt and 220 volt operation No change in the fuse is necessary when switching the LINE VOLTAGE SELECTOR switch between 110 volts and 220 volts 4 30 ADJUSTMENT AFTER REPAIR After any electrical component has been replaced the adjustment of that particular circuit should be checked as well as the adjustment of any closely related circuits Since the low voltage supplies affect all circuits adjustment of the entire instrument should be checked if component replacements have been made in these supplies or if the power transformer has been replaced See section 5 for a complete adjustment procedure Section 5 7904A CHECKS AND ADJUSTMENT This section provides procedures for checking the performance and for adjusting the 7904A These procedures are designed to compare the performance of this instrument with other measurement instruments of known accuracy to detect correlate or eliminate by adjustment any variat
425. lls the emitter of Q2151 along with them through C2154 and C2155 This positive shift on the emitter of Q2151 turns it off Now with C2151 conducting and Q2152 turned off the voltage on the emitter of Q2152 begins to go negative with C2154 and C2155 beginning to charge through R2155 When the emitter base junction of Q2152 becomes forward biased the oscillator again changes states and completes one cycle The signal produced by the oscillator at the collector of 02152 switches 02153 on and off to create the clock pulses used by the Lower Order Address Generator and the EPROM latch The oscillator will continue to run until the Timer Ready output at pin 13 goes positive and pulls up the base of Q2152 The Lower Order Address Generator is a 4 bit binary counter and consists of U2202B The negative going Timer Ready pulse is inverted by 02142 and used 10 reset U2202B The oscillator is also enabled by the Ready signal and begins providing the clock input at pin 13 The counter then begins at 0000 and counts at the frequency of the os cillator continuing to do so until the Ready signal goes posi REV NOV 1985 tive The Lower Order Address Generator s 4 bit output is connected to the four lower order address inputs on the Character Generator U2203 U2204 is an octal D type flip flop used as a latch to stabilize and synchronize the Character Generator EPROM output It is reset by the same signal that starts the oscillator and is clocked at
426. ly from the vertical portion of the X Y display In typical X Y displays no time base unit for Z Axis control a dc driven Z Axis circuit produces displays with nonuniform brightness A display may consist of a very dim transition between two bright spots see Fig 2 6A However when the time base unit is used Z Axis contro can be turned on only during the transition and therefore a uniform brightness display may be obtained see Fig 2 6B Z Axis control is accomplished by increasing the sweep rate until the desired portion of the display is blanked and then using the Triggering Level and Slope controls to view the appropriate portion of the X Y display The high horizontal bandwidth of the 7904A used in conjunction with Z Axis control from a time base unit allows observation of very fast transitions in X Y displays Option 2 adds a horizontal delay to the instrument permitting signal phase correction between the vertical and horizontal deflection system Also some vertical plug in units have a variable delay function that permits precise phase correction For further information refer 2 17 Operating Instructions 7904A 7904A Controis Vertical Mode Right Horizontal Mode Trig Vert Mode SIGNAL SOURCE AMPLIFIER AMPLIFIER BNC COAXIAL CABLES CONNECTOR Test Equipment Controls Amplifier
427. m the secondary of 114 Capacitors C103 C104 and R104 filter the rectified voltage CRT HEATER The CRT Heater voltage is provided by a separate 6 3 volt secondary winding of T14 The CRT Heater circuit is elevated to the cathode potential through R93 3 57 Theory of Operation 7904A ANODE VOLTAGE MULTIPLIER Positive accelerating potential for the crt anode is supplied by the seven times voltage multiplier contained within U21 The applied voltage to the input of U21 from the secondary of T14 is about three kilovolts peak to peak This results in an output voltage of about 21 kilovolts at the crt anode The limit output of U21 provides a dc level to the Intensity Limit circuit diagram 7 CRT CATHODE SUPPLY The negative three kilovolt 2965 V accelerating potential for the crt cathode is generated by a voltage doubler consisting of CR83 CR82 C82 and C84 High frequency filtering is accomplished by R84 C86 R86 and C89 Components R86 and C89 also provide an ac coupling path for error correction from the Cathode Supply Regulator stage CATHODE SUPPLY REGULATOR The Cathode Supply Regulator maintains the potential on the crt cathode and reduces ac ripple from the CRT Cathode Supply A sample of the output from the CRT Cathode Supply stage is connected to the Cathode Supply Regulator stage through divider resistors R52A R116 and Ri15 High frequency changes from the CRT Cathode Supply are coupled to the Cathode Su
428. mbly No Mfr t No Part Effective Dscont Name amp Description Code Mfr Part No A22R94 315 0393 00 RES FXO FILM 39K OIM 525 0 25W 5 668 NTR25J E39K0 A22R95 308 0804 00 RES FXD WW 0 025 OHM 55 0 5M 80009 308 0804 00 A22R96 315 0151 00 RES FILM 150 OHM 54 0 25W 57668 251 150 A22R97 315 0432 00 RES FXD FILM 4 3K OHM 5 0 25W 57068 251 04 3 A22R113 321 1713 07 RES FXD FILM 36K OHM 0 1 0 125W 9 19701 5033RE36K00B 22 114 321 0926 07 RES FXD FILM 4K 0HM 0 12 0 125W TC T9 19701 5033RE4K008 22 121 315 0512 00 RES FILM 5 1K OHM 5 0 250 57668 NTR25J EOSKI A22R122 315 0201 00 031871 RES FXD FILM 200 OHM 5 0 259 57668 252 200 A22R126 315 0131 00 RES FILM 130 54 0 25W 19701 5043CX130R0J A22R127 315 0203 00 RES FXD FILM 20K OHM 5x 0 25W 57568 NTR25 E 20K A22R128 315 0203 00 RES FXD FILM 20K OHM 5 0 25W 5 668 NTR25J E 20K AZ2R129 315 0101 00 RES FILM 100 5 0 25W 57668 NTR253 E 100E A22R131 315 0362 00 RES FXD FILM 3 6K OHM 52 0 25W 19701 5043CX3K600J A22R132 315 0151 00 RES FXD 150 54 0 25W 57668 NTR25J E150E A22R133 308 0804 00 RES FXD WW 0 025 OHM 5 0 5W 80000 308 0804 00 A22R134 308 0804 00 RES FXD WW 0 025 OHM 5 0 5W 80009 308 0804 00 A22R135 315 0470 00 RES FILM 47 5 0 25 5 668 NTR25J E47E0 A22R136 315 0432 00 RES FXD FILM 4 3K OHM 52 0 25W 57
429. merican 240 volt type power cord OPTION A5 The standard power cord is replaced with the Switzerland 220V 10A type power cord INSTRUMENT OPTION IDENTIFICATION Options 2 3 4 13 78 are identified by labels on the 7904A rear panel To identify Power Cord Options A1 A2 A3 A4 and A5 refer to Table 1 2 to determine the type of power cord used with your instrument Instrument Options 7904A instrument Option Option 2 mode phase correction Option 3 Electromagnetic Compatibility Option 4 4 x 5 cm display with P31 phosphor Option 13 4 x 5 cm display with P11 phosphor Option 78 8 x 10 cm display with P11 phosphor Option A1 Universal European 240 volt power cord Manual Section 1 General information 2 Operat ng instructions 3 Theory of Operation 5 Checks and Adjustment 2 Operating Instructions 4 Maintenance General Information General Information 1 General Information 1 General information TABLE 6 1 Option information Locator Location Tabie 1 3 Electrical Characteristics HORIZONTAL SYSTEM X Y Operation Description X Y Delay Compensation Option 2 Part Step 04 Check X Y Delay Compensation Part il Adjustment and Performance Check Step E8 Check Adjust X Y Delay Light Filter Cabinet Panel Removai CRT Table 1 3 Electrical Characteristics DISPLAY
430. millisecond time markers to the test oscilloscope external trigger input and to the noninverting vertical channel of the test oscilloscope use a bnc T connector Connect the 7904 CALIBRATOR output to the inverting input of the test oscilloscope Set the test oscilloscope Triggering Level control for a stable time mark display Set the test oscilloscope vertical deflection factors to display 2 divisions of CALIBRATOR signal and 1 division of time marker signal Set the test oscilloscope Vertical Mode to Add rate for 02 Set the test osciloscope sweep second division CHECK that the time required for the 1 millisecond time marks to drift from the positive level of the CALIBRATOR signal to the negative level and back to the positive level is more than 0 4 second 2 divisions This time can be measured directly from the display by observing the number of divisions that the markers move across the display area before it returns to the positive level ADJUST 1 kHz adjustment R375 on the A5 Mode Switch Board for minimum drift access to the adjustment is through the inside top of the vertical compartment C4 CHECK CALIBRATOR RISE TIME FALL TIME AND DUTY CYCLE NOTE If the preceding step was not performed first perform step C1 then proceed C4 SETUP CONDITIONS 7904A Controis No change in settings CALIBRATOR Test Equipment Controls Test Oscilloscope Sweep Rate 0 1 us di
431. mode 2 Check pre regulated power supplies 3 Check crt and E high voltage circuits 4 Check inverter F control circuit 5 Check inverter G circuit 5 Push the 7904A POWER button in to turn the instrument and note the trouble symptoms 6 Turn the 7904 off and proceed to the appropriate step in the Troubleshooting Procedure as indicated by the Trouble Symptom column in Table 4 2 TROUBLESHOOTING PROCEDURE Step A Check Line Fuse To check the line fuse perform the following procedure 1 Check the line fuse F10 located on the rear panel of the power supply unit for continuity and proper rating as given in Section 7 Replaceable Electrical Parts 2 If the line fuse is open replace with a new one of proper rating 4 9 Maintenance 7904A Step B Isolate Power Supply Malfunction from the Mainframe Circuitry To isolate the malfunction perform the following procedure WARNING Use extreme caution when troubleshooting in the power supply unit to avoid electric shock Stored dc potentials on the A23 Power Supply inverter circuit board remain long after the instrument is disconnected from the power source Verify that the power cord plug s disconnected and that the line storage capacitors A23C16 and A23C17 are completely discharged before attempting any repairs or resistance measurements A warning indicator neon bulb located on the A23 Inverter board flashes
432. mounting the assembly to circuit board Exercise care when mounting the frame elastomer contact holder hybrid IC assembly to the circuit board to prevent misalignment between the connector and board 4 26 Because of the close tolerances involved spec al care must be taken to assure correct index alignment of each Hypcon part during reassembly Failure to do so can result in a cracked hybrid substrate See Figure 4 14 for index locations If your instrument contains both the flush and stepped type of Hypcon connectors be careful not to mix the elastomer contact holders during reassembly The flush Hypcon connectors have green elastomer contact hoiders and the plastic frame is marked FLUSH The stepped Hypcons have neutral colored elastomer contact holders with a slight ridge or step on the contact surface the large frames are marked STEPPED The registration pins on the stepped plastic frame slightly longer than those on the flush frame The elastomer contact holder in the small stepped connectors is indexed differently than the large connectors Look for a smali gold arrow in one corner of the holder instead of a flat corner Match this corner arrow with the pointed corner of the plastic frame Give close attention to this indexing as it is easy to insert the elastomer contact holder incorrectly Differences also exist between the large flush and large stepped Hypcon circuit board receptacles
433. mp signal from the clock generator stage determines the repetition rate and pulse width of the Vertical Chopped Blanking pulses The delay ramp from pin 13 U4320 applied to pin 10 starts to go negative from a level of about 1 1 volts coincident with the leading edge of the clock pulse see waveforms in Fig 3 4 This results in a HI quiescent condition for the Vertical Chopped Blanking pulse The slope of the negative going delay ramp is determined by the clock generator stage As it reaches a level slightly negative from ground the Vertical Chopped Blanking pulse output level changes to the LO state and remains LO until the delay ramp goes again Notice the delay between the leading edge of the clock pulse generated by U4320 and the leading edge of the Vertical Chopped Blanking pulses The amount of delay between the leading edges of these pulses is determined by the delay ramp applied to pin 10 This delay is necessary due to the delay line in the vertical deflection system Otherwise the trace blanking resulting from the Vertical Chopped Blanking pulse would not coincide Theory Operation 7904A TABLE 3 10 input Output Combinations for the Vertical Chopped Blanking Stage Has no effect in this case sse s eexwewm _ 3o o o m to to to to _ OUTPUT H NO VERTICAL CHOPPED BLANKING PULSES AT OUTPUT Ramp signal considered LO when more
434. ms three major functions 1 Receives a External signals from the Z Axis Input and the Single Sweep Reset input b Internal signais from the Readout system the front panel Mode Switch and Intensity controls and from aH plug in compartments through the Main Interface 2 Sends control signais to all plug in compartments via the Main Interface 3 Develops the Z Axis signal which drives the Z Axis Amplifier The Z Axis Amplifier provides the drive signal to control the intensity level of the crt display Theory of 7904 FROM VERTICAL PLUG EN COMPART MENTS HORIZONTAL PLUG IN COMPART MENTS HORIZONTAL SIGNALS VERTICAL SIGNALS READOUT TO FROM DATA READOUT INTERRO GATING PULSES SAWTOOTH SIGNALS FROM HORIZONTAL PLUG IN COMPARTMENTS TO FROM OPERATING ALE DATA PLUG IN COMPART CONTROL MENTS SIGNALS FROM A HORIZONTAL PLUG IN COMPARTMENT FROM B HORIZONTAL PLUG IN COMPARTMENT TRIGGER SELECTOR SiG QUT MODE iis CALIBRATOR CALIBRATOR X Y HORIZONTAL HORIZONTAL CHANNEL SWITCH AMPLIFIER EE VERTICAL DELAY gt CHANNEL 7773 x 5 5 READOUT READOUT j SYSTEM Y READOUT VERTICAL INTENSITY LIMET SIGNALS 4 amp INTENSITY LIMITER i DISPLAY CONTROL INTENSITY REFERENCE GRATICULE READOUT SINGLE SHOT amp FOCUS 1 AMPLIFIER B SINGLE
435. n 15 switches the Time Siot Counter to the next output line causing the output signal to be sequenced consecutively from time slot 1 through time siot 10 Figure 3 14 shows the time relationship of the time slot pulses No tice that only one line carries a time slot pulse at any given time When time slot 10 is completed a negative going end of word puise is produced at pin 2 The end of word pulse provides a drive pulse for the Word Trigger stage and also provides an enabling level to the Display Skip Generator during time siot 1 only Pin 16 is a reset input for the Time Slot Counter When this pin is held LO the Time Slot Counter resets to time slot 1 WORD TRIGGER The Word Trigger U2127B is a single shot multivibrator that provides a reset pulse for the Horizontal Character Position Counter stage The negative going end of word pulse from pin 2 of U2159 triggers the single shot and causes its output to go high at pin 11 CHANNEL COUNTER Channel Counter U2127A is a binary counter that produces the Channe Address Code for the Column and Row De coder stages and the Output Amplifier stages This code instructs these stages to sequentially select and display the 8 channels of data from the plug ins Table 3 13 gives the 8 combinations of the Channel Address Code and the resul tant channel selected with each combination HEV NOV 1985 TABLE 3 13 Channel Address Code SN B031767 amp Above Pin 5 Pin 4 Pin 3 Channel U2127
436. n encoded during time slot 1 was only provided to set the memories and not intended to be displayed on the CRT at this time the Display Skip output prevents a readout display during this time slot During time siot 5 a memory within U2232 is interrogated If information was stored in this memory a positive going out put is produced at pin 7 This pulse is connected to pin 10 of the Column Decoder through Q2243 to add one unit of cur rent at the input of the Coiumn Decoder This produces a zero after the character displayed during time siot 4 During time siot 6 another memory within U2232 is interrogated to see if another zero should be added if another zero is nec essary a second positive output is produced at pin 7 which again resuits in a column 1 output from the Column Decoder and a second 0 in the CRT display Finaily another memory within U2232 is interrogated during time slot 8 to determine whether the prefix should be changed or left at the that was encoded If data has been encoded that calls for a shift in prefix a negative going output level is produced at pin 7 This negative level sub tracts one unit of column current from the data at the input to the Column Decoder Notice on the Character Selection Matrix of Figure 3 20 that when row 4 is programmed a reduction of one column results in a one column shift of the prefix For example with the 1004 V program shown in Fig ure 3 15 If the data received from th
437. n of this stage is fixed by the values of the resistors in the circuit DISPLAY SEQUENCE Figure 3 19 shows a flow chart for the Readout System This chart illustrates the sequence of events that occurs in the Readout System each time a character is generated and displayed on the crt READOUT SYSTEM SN B031767 amp Above The Readout System provides an alphanumeric display of information encoded by the plug in units This display is pre sented on the CRT and is written by the CRT beam on a shared basis with the analog waveform display REV NOV 1985 Theory of Operation 7904A The following terms are used to describe the Readout System Character A single number letter or symbol dis played on the CHT either alone or in combination with other characters Word A group of related characters In the Readout System a word can consist of up to 10 characters Frame A display of all words for a given operating mode and plug in combination Up to 8 words can be displayed in one frame Figure 3 8 shows the position of each word in a complete frame Column One of the vertical lines in the Character Se lection Matrix see Fig 3 20 Columns 0 column zero through C 10 column 10 can be addressed by the system Row One of the horizontal lines in the Character Se iection matrix Rows R 1 row 1 through R 10 row 10 and R 14 row 14 can be addressed by the system Time Slot A location in a pulse
438. nal is determined by the B TRIGGER SOURCE switch In the VERT MODE position of the TRIGGER SOURCE switch the output signal is determined by the setting of the VERTICAL MODE switch The output signal in the LEFT and RIGHT positions of the VERTICAL MODE switch is obtained only from the selected vertical unit in the ALT position of the VERTICAL MODE switch the output signal at the SIG OUT connector switches between signals from the two vertical units along with the crt display However the vertical output signal in the ADD position is a composite signal the CHOP position the signal out is derived from the LEFT VERT plug in The LEFT VERT and RIGHT VERT positions of the B TRIGGER SOURCE switch are independent of the selection of the VERTICAL MODE switch and provide the vertical output signal only from the selected vertical unit even when it is not selected for display by the VERTICAL MODE switch Probe Power The two PROBE POWER connectors on the rear panel of this instrument provide operating power for active probe systems is not recommended that these connectors be used as a power source for applications other than the compatible probes or other accessories which are specifically designed for use with this system DISPLAY PHOTOGRAPHY A permanent record of the crt display can be obtained with an oscilloscope camera system The instruction manual for the Tektronix oscilloscope cameras include complete instructions for
439. nalog data is connected back to the Readout System via terminal B37 of the plug in interface PLUG IN 15 1 R10 75 K Cy R110 150 ROW O ANALOG READOUT SYSTEM R111 75 TS 2 R20 150 K 120 150 K J 153 R30 150K INVERT R130 13 Qr UNCALIBRATED T 4 R140 75 TIME SLOT A32 PULSES FROM ADOUT SYSTEME R141150K TS 5 831 8142 37 4 16 py a TS 8 R80 50 A30 180 150 COLUMN ANALOG 37 4K DATA TO Bo eae ein i Adis READOUT SYSTEM gt TS 10 A29 NOT USED IN STANDARD FORMAT 4593 64 Figure 3 15 Typical encoding scheme for voltage sensing plug in unit Coding shown for deflection factor of 100 microvolts 3 31 Theory of Operation 7904A The column analog data is defined by resistors R110 through R190 The program resistors are connected to the time slot lines by switch closures to encode the desired data The data as encoded by the circuit shown in Figure 3 15 indicates a 100 microvott sensitivity with the crt display inverted and calibrated deflection factors This results in the idealized output current waveforms shown in Figure 3 16 at the column analog data output terminal A37 of the plug in interface Resistor R111 connected between time slot 1 and the column analog data output encodes two units of
440. ndie Tektronix Part shaft 003 0307 00 and bit Tektronix Part 003 0310 00 19 Tool Alignment Length of shaft 1 inch Adjust various controis Tektronix Part 003 0000 00 20 Time base unit TEKTRONIX dual time base Used to check Aux Z axis TEKTRONIX 7B53A or 7 92 Time with Aux Z axis output circuitry Base used for Adjustment only not used for Performance Check REV MAR 1984 5 13 Checks Adjustment 7904A PART I PERFORMANCE CHECK The following procedure Part I Performance Check verifies electrical specifications without removing instrument covers or making internal adjustments All tolerances given are as specified in the Specification tables section 1 in this manual Part Il Adjustment and Performance Check provides the information necessary to 1 verify that the instrument meets the electrical specifications 2 verify that all controls function properly and 3 perform all internal adjustments A separate Operators Checkout Procedure is provided in section 2 for familiarization with the instrument and to verify that all controis indicators and connectors function properly See Table 5 1 Checks and Adjustments Procedure Electives at the beginning of this section for information on performing a Partial Part Check procedure INDEX TO PERFORMANCE 4 Check Vertical Amplifier 500 MHz Gain 5 27 CHECK PROCEDURE 9 Check Vertical Channel Isolation 5
441. ne of the graticule Do not change the test oscilloscope Position controls after setting this ground reference c Within the plug in extender disconnect the top connector on the left and right sides labeled A20 and 820 Connect each female connector to one of the test oscilloscope channeis with the 42 inch 50 ohm coaxial cables and 50 ohm bnc terminations omit the 50 ohm bnc terminations if the test oscilloscope has a 50 ohm input impedance d Set both channels of the test oscilloscope for dc input coupling 5 52 EXAMINE test oscilloscope display for a dc level within 1 division 50 millivolts of the ground reference level in the LEFT RIGHT and ADD positions of the 7904A VERTICAL MODE switch ADJUST B DC Center adjustment R455 on the A14 Trigger Selector Board for a dc level within 1 division 50 millivolts of the ground reference level in the LEFT RIGHT and ADD positions of the VERTICAL MODE switch install the signal standardizer in the LEFT VERT compartment Set the VERTICAL MODE switch to LEFT Set the signal standardizer Test Selector to Trigger Gain and the Rep Rate to 1 MHz Use the signal standardizer Position control to align the bright trace displayed on the test oscilloscope with the center graticule line EXAMINE the test oscilloscope display for nine traces with six divisions of vertical defiection between the center seven traces within 0 6 division 300 millivolts within 30 millivolts
442. nes whether the A sweep or the B sweep sawtooth signal provides the SAWTOOTH signal The unused sawtooth signal is terminated by R1941 Transistors Q1943 Q1942 Q1946 form an inverting feedback amplifier Gain of the stage is about 2 as determined by the ratio of feedback resistor R1944 to the input resistance made up of R1940 and on diagram 3 either R93 or R95 depending on which sawtooth source is selected The front panel GATE switch 51930 selects the gate signal from either A or B time base unit The unused gate is terminated in 1931 Before a gate occurs Q1934 is biased off and Q1938 is conducting its collector potential is low enough to cut off Q1928 When a gate occurs it is coupled to the base of Q1934 causing it to conduct thereby cutting off Q1938 The current through R1911 now flows through Q1928 to produce the GATE signal For certain applications the Delay Gate output J99 on the Main Interface board diagram 3 may be connected to either of the gate inputs to the Gate Amplifier This provides a delay gate at the GATE front panel output END OF GATE PULSE GENERATOR The End of Gate signal at the collector of Q1934 is coupled through C1914 to the base of Q1916 This turns on 91916 and generates a negative pulse which activates the Readout Single Shot and Graticule Illumination stage when selected GRATICULE ILLUMINATION Variable resistor R1900 GRAT ILLUM determines the brightness of the graticu
443. ng conductor of the mainframe power cord To avoid electrical shock plug the mainframe power cord into a properly wired receptacle before connecting to the product input or output terminals A protective ground connection by way of the grounding conductor in the mainframe power cord is essential for safe operation DANGER ARISING FROM LOSS OF GROUND Upon loss of the protective ground connection all accessible conductive parts including knobs and controls that may appear to be insulating can render an electric shock DO NOT OPERATE IN EXPLOSIVE ATMOSPHERES To avoid explosion do not operate this product in an atmosphere of explosive gasses DO NOT REMOVE COVERS OR PANELS To avoid personal injury do not remove the product covers or panels Do not operate the product without the covers and panels properly installed DO NOT OPERATE WITHOUT COVERS To avoid personal injury do not operate this product without covers or panels installed vii 7904A Instruction Dd f TS EON ES 22 d re POSSE SE 52 Que eee RS SUE Md iD Tektronix 7904A OSCILLOSCOPE cc ONTERSSI PES Se sss E SOS ue SSE 2 SESS M NWN S Me 2 Mum QNS SS 9555 NS ONUS 2 55555 DD 4593 3 7904A FEATURES The TEKTRONIX 7904A Oscilloscope is a solid state high performance 500 MHz vertical bandwidth instrument des
444. ng pulse to the Z Axis Logic stage see Diagram 4 to blank the crt before the display is switched to the Readout System it also produces the strobe pulse through Q2138 and CR2142 to signal other stages within the Readout System to begin the sequence necessary to produce a character The collector level of Q2138 is also connected to Symbol Character Generator U2272 by way of CR2140 This activates U2272 during the quiescent period of the strobe pulse collector of Q2138 negative and diverts the output current of Row Decoder U2185 to row 2 The purpose of this configuration is to prevent the Zeros Logic and Memory stage U2232 from storing incorrect data during the quiescent period of the strobe pulse When the strobe pulse goes positive CR2140 is reverse biased to 1195 30 4593 60 CHARACTER SCAN PIN 16 SN B031766 amp BELOW Z AXIS LOGIC OFF COMMAND PIN 14 HORIZONTAL OFF COMMAND PIN 13 READOUT INTENSITY PIN 12 NOTE TEST OSCILLOSCOPE EXTERNALLY TRIGGERED FROM TP2251 SN 8031766 amp BELOW U2127 PIN 5 SN B031767 amp UP Figure 3 12 Detail of output at pins 12 13 14 and 16 of U2126 3 27 Theory of Operation 7904A disconnect 02138 from 02272 and allow the Row Decoder to operate in the normal manner The next signal to be produced is the X Y Inhibit Command at pin 13 This positive going signal disconnects the plug in signals from the vertical and horizontal de
445. nge is sensed at the secondary of T35 by 075 as previously described Transistor Q34 is held off at this time and ls flows due to the inductive action of L37 pulling the anode of CR34 to a voltage greater than the positive supply voltage After a time determined by the Inverter Control stage Q40 conducts the current labeled 14 and the cycle repeats itself OVER VOLTAGE STOP Whenever the voltage across the primary of T110 exceeds a safe level the Over Voltage Stop stage shuts ADD NOV 1985 Theory of Operation 7904A 30 V 2 UNREGULATED DC INPUT VOLTAGE 230 V 2 PHASE SENSE TO U75 B TOTAL INVERTER CURRENT COMPOSITE WFM IT VOLTAGE AT POINT W Ew D VOLTAGE ACROSS T110 amp T35 EY Figure 3 24 A Representation of Inverter stage Idealized waveforms of B total Inverter current C Voltage across CR41 and D Voltage across primaries of T110 and T35 ADD NOV 1985 3 61 Theory of 7904 down the Inverter to protect inverter components from damage For example this stage activates whenever the normal voitage regulating path through 052 and T30 is inoperative Capacitor C43 charges through R44 and CR38 to the peak voltage across the primary of T110 If this voltage exceeds a safe level Q45 conducts to cause Q43 and Q46 to turn on When 046 turns on the base drive winding of T30 is short circuited which stops the Inverter switching action Since Q43 is tu
446. nit 4 12 6 NOTE if the variable transformer s output is increased past the po nt where the voltmeter just reaches a reading of 108 volts the 7904A will switch to pulse mode If the power supplies stabilize check A12U75 and the inverter contro circuit for a malfunction If the 7904A continues in the pulse mode proceed to Step G of this procedure Step G Check Inverter Circuit To check the inverter circuit perform the following procedure 1 Disconnect the 7904 power cord plug from power source and discharge the line storage capacitors following the procedure given under Access to Components in the Power Supply Unit Remove Q34 Q40 CR34 and CR41 on the A23 Power Supply Inverter circuit board and check the characteristics of each with a curve tracer Install the checked or replaced components in the A23 Inverter board Replace the line fuse if it is open If the faulty component was not found check Q43 Q45 and VR45 on the A23 Power Supply Inverter circuit board with a curve tracer NOTE A shift in the zener voltage of VR45 can cause erratic operation of the inverter circuit lf the 7904A continues in the pulse mode or continues to blow line fuses check the current waveform through T30 on the A23 Power Supply Inverter circuit board To do this first repeat part 1 of this step Then connect a current probe from the test oscilloscope to the gray lead that passes through toroid transformer T
447. nnecting resistors between them and the time slot input lines The resultant output is a sequence of 10 analog current levels that range from 0 to 1 milliampere 100 microamperes step on the row and column output lines This row and column corresponds to the row and column of the Character Selection Matrix in Figure 3 9 The standard format for encoding information onto the output lines is given in Table 3 11 Special purpose plug in units may have their own format for readout these special formats will be defined in the manuals for these units TABLE 3 11 Standard Readout Format Time Slot Number Description TS 1 Determines Decima Magnitude number of zeros displayed or prefix change information or the IDENTIFY function no display during this time slot TS 2 indicates normal or inverted input no display for normal TS 3 indicates calibrated or uncalibrated condition of plug in variable control no display for calibrated condition 15 4 Scaling TS 5 Not encoded by plug in unit Left TS 6 blank to allow addition of zeros by TS 7 Readout System TS 8 Defines the prefix which modifies the units of measurement TS 9 Defines the units of measurement TS 10 of the plug in unit May be standard unit of measurement V S etc or special units selected from the Character Selection Matrix The encoded column and row data from the plug in units is selected by the Column Data Switch and Row Data Switch stages respect
448. nnectors J202 J203 and J402 J403 to the output 4270 J271 into a load of 50 ohm per side is one The dc output level of U274 is zero volts R235 sets the dc Centering and R279 adjust the Common Mode voltage Thermal compensation for 12232 and U274 is provided by four time constants R240 and C240 C237 R250 and C250 R270 and C270 The operation of the B trigger selector is similar except for the signal pickoff of pin 2 and pin 4 of U474 which is used to generate the Vertical Signal Out VERTICAL SIGNAL OUTPUT AMPLIFIER A differential signal is picked off at pin 2 and pin 4 of 0474 and is amplified by 0492 Before the signal reaches the input of U492 it passes through compensation circuit consisting of C483 R483 R486 L486 R496 C492 and R493 The characteristic impedance of this circuit is 100 ohms differentially and terminates the 50 ohm strip transmission lines running from the pickoff points at pin 2 and pin 4 of U474 At pin 2 and pin 4 there is an uncertainty in the dc common mode level due to the 5 voltage tolerance of zener diodes VR437 and VR447 integrated circuit U452B passes on this uncertainty for biasing 0492 The output signal at J496 is centered at 0 voit by R485 The signal out amplitude is 25 millivolts division of vertical deflection into a load of 50 ohms and 0 5 voit division of vertical deflection into a 1 megohm load Two time constants R480 1480 and R490 and C490 provide thermal
449. nnel Switch Board to align the trace with the center graticule line 5 61 Checks and Adjustment 7904A Part li Adjustment and Performance Check F3 CHECK ADJUST VERTICAL AMPLIFIER F4 CHECK VERTICAL LOW FREQUENCY GAIN A18R211 LINEARITY NOTE NOTE If the preceding step was not performed first If the preceding step was not performed first perform step F1 then proceed perform step F1 then proceed F3 SETUP CONDITIONS F4 SETUP CONDITIONS 7904A Controls No change in settings 7904A Controls VERTICAL MODE P 5 281 50 go 8 58 55 Sol ac cf 5 E e Time Base Test Equipment Controls Time Base Sweep Rate 1 ms div Triggering Auto AC Internal Test Equipment Controls Time Base Sweep Rate 1 ms div Triggering Auto AC External Signal Standardizer Signal Standardizer Vert Horiz Gain Vert or Horiz Step Resp Rep Rate 4593538 4593 537 a Position the signal standardizer display to align the Set the signal standardizer Amplitude and Position bright center trace with the graticule center line controls so the display is exactly two divisions n amplitude in the center of the graticule area b CHECK for one trace per graticule division within 0 05 division over the center six graticule divisions b CHECK position the two division display vertically Note the exact error for comparison in part f and check for not more than 01 division of compression or ex
450. normally require customer verification deflection within 25 Satisfactory operation substantiated at factory Into 1 MQ 0 5 V div of vertical defiection within 25 maximum output 2 V PEENE Se UE NRI Bandwidth into 500 Varies with vertical plug in selected See 7904 Oscillo scope Vertical System Specification in Table 1 7 C2 Check Vertical Signal D4 Check Adjust Vertical Signal DC Centering Out DC Centering READOUT DISPLAY MERE internal switch on Readout F2 Check Readout Modes G5 Check Readout Modes Board must be in Free Run osition Continuously displayed READOUT controi not in PULSED position Single shot operation DC Centering OV within 1 V into 1 Readout Modes Not Labeled on Front Panel PULSED Pulsed Source Selected by front panel switches GATE Triggered by the trailing edge of ihe GATE selected by the front panei Switch EXT Controlled through rear panel remote control connector Manual trigger indepen dent of other pulse sources pe ANn 9 7 Checks and Adjusiment 7904A Characteristics Graticule Type Area Standard Instrument and Option 78 Option 4 Option 13 Phosphor Standard Option 4 Option 78 Option 13 Beamfinde
451. nse line The divider ratio of R61 and R62 sets pin 3 of U64A at 15 volts Any change in the output level of the 15 volt supply appears at pin 2 of 64 as an error signal This results in an opposite change at the output pin 1 of U64A which is conveyed to the 15 voit series regulator transistor Q74 through CR64 and Q68 to correct the error in the output voltage of the supply Diode CR76 limits the output of this supply to about 0 6 volt if it is shorted to one of the negative supplies 50 V REGULATOR Operation of the 50 V Regulator is basically the same as described for the 50 volt supply current limiting operates in a similar manner as described for the 50 volt supply Error voltage to pin 2 of U45 is provided by divider R45 R46 and is referenced to the 50 VS sense line The divider ratio of R45 and R46 sets the level at pin 2 of U45 at zero volts when the output of this supply is correct The protection diode CR58 limits the output voltage of this supply to 0 6 volt should the supply be shorted to a positive supply FAN CIRCUIT SN B039999 amp Below The fan motor used in this instrument is a brushless dc motor using Hall Effect devices The two Hall Effect devices sequentially drive the four transistors Q20 A B C and D which in turn contro the current flow through the four field windings The fan motor speed is regulated by limiting the current flow through Q10 Diodes CR21 CR22 CR23 and CR24 rectify the b
452. nsified zone is too No contrast control bright and may be the only part of the display visible 7514 All 7814 will not alternate with 7814 does not provide proper other sweep plug ins holdoff puises TABLE 1 7 7904 Oscilloscope Vertical System Specification Amplifier _ Vert Sig Out Plug in Probe Bandwidth Rise Time Ext Cal Unit MHz i 0 to 50 BW Tr i i MHz ns 7A11 4 integral 250 _ 244 2 5 7A12 120 110 3 2 __________ _ 053 os em 100 35 7TA13 P6053B 1 5 2 5 3 5 100 3 5 7A14 Mira Uo oo e mon qo 6022 120 100 3 5 70 5 0 140 2 5 15 L 8 70 5 0 ENCODER CPUS 500 300 12 mas t 500 300 1 2 bi 4800 REED 1 MHz 1 0 350 Any within 10 10 9 7 24 350 140 2 5 72 300 __ 6 5 __ 200 140 2 5 None i e E _ a Pos 74 n Deflection Factor accuracy is checked as follows EXT CAL 0 C to 50 20 Plug in gain set at a temperature within 10 C of operating temperature using an external calibrator whose accuracy is within 0 25 INT CAL 15 C to 35 C Plug in gain set while operating within a temperature range of 15 to 35 C using th
453. nter is also connected to pins 1 8 and 15 of this stage The Channel Address Code directs the Format Generator to add current to the X and Y signals to deflect the crt beam to the area of the crt associated with the plug in channel that originated the information see Fig 3 8 The Channel Address Code and the resultant word positions are shown in Table 3 12 The Ready signal at pin 13 coincident with the X Y inhibit Command output activates this stage when a character is to be displayed on the crt Variable resistor R2273 determines the horizontal and vertical size of the displayed characters The character position current from the Decimal Point Logic and Character Position Counter stage is added to the X horizontal input signal to space the characters horizontally on the crt see previous discussion Y OUTPUT The Y output signal at pin 6 of Format Generator U2284 is connected to the Y Output amplifier Q2287 and Q2299 This stage provides a low impedance load for the Format Generator while providing isolation between the Readout System and the driven circuits Vertical Separation adjustment R2291 changes the gain of this Pu Stage to control the vertical separation between the readout words displayed at the top and bottom of the graticule area X OUTPUT The X Output amplifier Q2286 and Q2296 operates like the Y Output amplifier to provide the horizontal deflection from the readout signal available at pin 4 of U2284 The gai
454. o a compartment align the slots in the top and bottom of the plug in unit with the associated guide rails within the plug in compartment Insert the plug in unit into the compartment until it locks into place To remove a plug in unit pull out on the release latch To meet the EMC electromagnetic compatibility specifications cover all unused plug in compartments with an EMC shielded blank plug in panel Tektronix Part 016 0155 00 The gain of the 7904 vertical and horizontal systems have been normalized to allow plug in units to be interchanged among plug in compartments without adjustment of the system The basic performance of the plug in units should be checked when installed to verify their accuracy refer to the operating instructions in the plug in unit manual CONTROLS AND CONNECTORS The 7904A front and rear panels are shown in Figure 2 1 and Figure 2 2 A brief functional description of each controi and connector is included in the illustration Refer to Detailed Operating Information for additional information FRONT PANEL COLOR CODING The 7904A front panel is color coded to define areas by function Blue identifies the display mode controls green identifies triggering controls The gray tint blocks have no functional assignment but indicate the relationship among controls and or connectors OPERATORS CHECKOUT PROCEDURE The Operators Checkout Procedure may be used to verify proper operation of the front pane
455. o be produced by the Character Generator stage These outputs are also used at other points within the system to indicate when certain information has been encoded One such stage is the Zeros Logic and Memory During time slot 1 TS 1 this stage checks if zero adding or prefix shifting information has been encoded by the plug in unit and stores it in the memory until time siots 5 6 or 8 After storing this information it triggers the Display Skip Generator stage so that there is no display during time slot 1 as defined by Standard Readout Format see Table 3 11 When time slots 5 6 and 8 occur the memory is addressed and any information stored there during time siot 1 is transferred to the input of the Column Decoder stage to modify the analog data during the applicable time slot Also the Zeros Logic and Memory stage produces the IDENTIFY function When time siot 1 is encoded for IDENTIFY column 10 row 3 this stage produces an output level which connects the Column Data Switch and How Data Switch to a coding network within the Readout System Then during time slots 2 through 9 an analog current output is produced from the Column Data Switch and Row Data Switch which addresses the correct points in the Character Selection Matrix to display the word IDENTIFY on the crt The Zeros Logic and Memory stage is reset after each word by the Word Trigger pulse The Character Generator stages produce the characters which are disp
456. o forward bias the associated diodes CR2162 and CR2163 CR2166 and 2167 CR2170 and CR2171 or CR2174 and CR2175 The for ward biased diodes cause the channel switches to bypass the encoded data from the inhibited channel However since REV NOV 1985 it may be desired to display information from pose plug in units even through they do not produce nor waveform display on the CRT a feature is provided to over ride the channel inhibit This is done by applying a LO to the associated Force Readout input The LO level diverts the HI channel inhibit current and allows the data from this plug in unit to reach the Column Data Switch even though it has not been selected for display by the mode switch Row Match adjustment R2183 sets the gain of the Row Data Switch to match the gain of the Row Decoder for cor rect output Column Match adjustment R2243 performs the same function for the Column Data Switch stage DISPLAY SKIP GENERATOR The Display Skip Generator is made up of Q2223 012226 02227 and 02229 This stage monitors the time multiplexed column data at the output of the Column Data Switch during each time siot to determine if the information is valid data that should resuit in a CRT display Quies cently about 100 microamperes of current flows through R2242 from 02243 and the Zeros Logic and Memory stage The purpose of this quiescent current will be discussed in connection with the Zeros L
457. obtaining waveform photographs The crt bezel provides integral mounting for Tektronix oscilloscope cameras The three pins located on the side of the crt bezel provide power to compatible camera systems Control signals are also received from Tektronix automatic cameras to allow camera controlled singie shot photography see camera manual for further information If the readout portion of the display is to be included waveform photographs the following suggestions will aid in obtaining good photographs 1 Focus the crt display Focus the camera on the readout portion of the crt display The auto focus feature of this instrument will maintain the traces at _ optimum focus 2 Set the READOUT INTENSITY control for the minimum setting that allows the characters to be written This normally occurs at a slightly lower intensity level than is necessary for complete writing of the waveform display Some experimentation may be necessary to establish the correct level Too high a setting of the READOUT intensity control will result in a broad poorly defined photograph of the readout display 3 lf single shot photography is used set the READOUT and GRAT ILLUM controls to the PULSED position see Readout Display and Graticule Illumination for complete operating information This allows the Readout display and graticule illumination to occur in a single shot manner after the trace is complete be sure the camera shutt
458. ocating the procedures Part and Part 1 that check and or adjust the instrument to meet the applicable electrical specifications For example If the A22 LV Regu lator board has been repaired or replaced use Table 5 2 to locate the electrical specifications affected by the repair or replacement Then note the title of the procedure in Part or Part Il in which those specifications are checked and or adjusted Use the index provided at the front of Part and Part 8 to determine the page number of the desired procedures AUX Z AXIS CHECK a Install a dual time base unit into the horizontal compartment b Set the time base as follows Time Div 1ms Diy d Time Div 1 ms Delay Time Mult 5 0 Dly d Trig Level CHECK for approximately 1 division of intensified trace in the middie of the screen Runs After Delay Time TABLE 5 2 Performance Check Summary Performance Characteristics Requirements Part Adjustment and Performance Check Procedure Title Part Performance Check Procedure Tiile Deflection Factor Compatible with 7000 Series plug in units Difference Between 1 or less Vertical Compartments Low Frequency Linearity 0 1 div or less compression or expansion of a center screen 2 div signal positioned anywhere vertically within Varies with plug in unit selected See 7904A Oscillo Scope Vertical System
459. oceed G2 SETUP CONDITIONS 7904A Controls No change in settings Test Equipment Controls No equipment necessary a Set the POWER switch to OFF b Remove Q2225 from its socket on the A15 Readout System Board C Set the POWER switch to on d Set the READOUT INTENSITY control for visible characters all zeros NOTE The following tolerances are provided as guides to correct instrument operation and are not instrument specifications EXAMINE the crt display for two rows of zeros 40 zeros to a row with no character overlap The two rows of zeros shouid be located vertically in the middle of the top and bottom divisions of the graticule see Fig 5 4 5 69 Checks and Adjustment 7904A Part lI Adjustment and Performance Check TE cena eem Lucas O PEDA 9 1 E 4 i ae 809 00000000000 000 000520000000 000000 200000 po poodpoogpocd ines e Ox ee i amt vas aad C1676 5 Figure 5 4 Readout display with Q2225 removed NOTE The MVA Center Main Vertical Amplifier Adjustment R736 must be correct before making the next adjustment Refer to F Vertical System procedure t ADJUST Vertical Separation adjustment R2291 on the A15 Readout System Board and R O Center adjustment R737 on the A18 Vert
460. ockwise B TRIGGER SOURCE VERT MODE oath ERA Midrange READOUT orai as Dau OFF detent GRAT ILLUM ocio orn ne xar abel erisa Midrange CONTROL ILLUMINATION MEDIUM rear panel 13 Coaxial Cable two 42 inch required 15 Adapter bnc T A2 CHECK GEOMETRY NOTE First perform step A1 then proceed A2 SETUP CONDITIONS 7904A Controls VERTICAL MODE hid Mer das ALT HORIZONTAL MODE CHOP and Midrange Signal Standardizer Time Base Signal Standardizer Time Base Test Equipment Controls LEFT VERT and HORIZ Signal Standardizers ucl Vert or Horiz Pm 100 kHz RIGHT Time Bases Sweep 2 us div TAGQSTING esee es ea ess Auto AC External 4593 410 a Set both signal standardizer Position controls to superimpose the crosshatch display over the vertical and horizontal graticule center lines the intensified vertical and horizontal traces should be aligned with the vertical and horizontal graticule center lines b Setthefront panel FOCUS and INTENSITY controls for a well defined display NOTE The front panel TRACE ROTATION adjustment may need to be set for optimum trace to graticule alignment c CHECK that the vertical and horizontal traces which cross
461. odes A horizontal unit only ALT Dual sweep alternates between horizontal units CHOP Dual sweep chops between horizontal units B B horizontal unit only General Information 7904A TABLE 1 3 CONT Electrical Characteristics Characteristics Performance Requirements HORIZONTAL SYSTEM CONT 2 or less from dc to at least 35 KHz Phase Shift Between Vertical and Horizontal Systems With Option 2 Wave Shape Polarity Output Voitage into 2100 Into 500 4 mV 40 mV 0 4 V Output Current 40 mA available through CALIBRATOR output with optional bnc to current loop adapter CALIBRATOR switch must be set to 4 V for calibrated output Amplitude Accuracy P P Voltage Within 1 Repetition Rate 1 kHz within 0 25 Duty Cycle 49 8 to 50 2 Rise Time Time 500 ns less into 100 pF or less SIGNAL OUTPUTS SAWTOOTH Selected by front panel switch A HORIZ time base unit B B HORIZ time base unit Polarity Positive going with baseline at 0 V within 1 V into 1 Output Voltage Rate of Rise into 50 0 50 mV unit of time selected by time base unit time div switch within 15 100 ns div maximum sweep rate into 1 1 V unit of time selected by time base unit time div switch within 10 1 us div maximum sweep rate GATE Source Selected by front panei switch A Gate derived from HORIZ time
462. of the low pass and all pass network time delays Capacitor C804 is adjusted to match the horizontal system time delay to the vertical system time delay up to at least one megahertz Time Base Operation When the plug in unit installed in the HORIZ compartment is operated as a standard time base unit to produce a horizontal sweep the B delay compensation network is disabled In this condition the X Y compensation command is which disables relays K812 and K815 Therefore the horizontal signal passes undelayed to the Horizontal Channel switch X Y Operation lf the time base unit installed in the HORIZ compartment is operated as an amplifier or if an amplifier unit is installed in the B HORIZ compartment the X Y compensation command to the B delay compensation network drops to the LO level zero volts This activates relays K812 and K815 to connect the delay compensation into the circuit HORIZONTAL AMPLIFIER The Horizontal Amplifier circuit amplifies the push pull horizontal deflection signal from the plug in unit installed in either horizontal compartment and connects it to the horizontal deflection plates of the crt A schematic diagram of the Horizontal Amplifier is given on diagram 11 in Section 8 of this manual Diagrams and Circuit Board Illustrations The schematic is divided by a gray shaded line separating the circuitry into major stages These stages aid in locating components mentioned here Sub headin
463. ogic and Memory stage and the Decimal Point Logic and Character Position Counter stage This Word Trigger stage can also be advanced to jump a complete word or a portion of a word when a Jump Command is received from the Row Data Switch stage TIMER The Timer stage establishes the timing sequence for ali circuits within the Readout System This stage produces 7 time related output waveforms see Fig 3 11 The triangle waveform produced at pin 6 forms the basis for the remaining signals The basic period of this triangle waveform is about 250 microseconds as controlled by RC network R2135 and C2135 The triangle waveform is clipped and amplified by U2126 to form the trapezoidal output signal at pin 10 The amplitude of this output signal is exactly 15 volts as determined by 92126 exact amplitude is necessary to accurately encode data in plug in units see Encoding the Data The trigger output at pin 5 provides the switching signal for the Time Slot Counter and Word Trigger stages REV NOV 1985 VERTICAL AND Theory of Operation 7904A The signals at pins 12 13 14 and 16 are produced only when the triangle waveform is on its negative slope and the trapezoidal waveform has reached the lower level The timing sequence of these waveforms is important to the operation of the Readout System see expanded waveforms in Fig 3 12 The Z Axis Inhibit command at pin 14 is produced first This negative going signal provides a blanki
464. ogic and Memory stage This current biases Q2223A so that its base is about 0 2 volt more positive than the base of Q2223B in the absence of column data Therefore since Q2223A and Q2223B are connected as a comparator Q2223A will remain on unless its base is pulled more negative than the base of Q2223B The analog data output from the Column Data Switch pro duces a 0 5 volt approximately change for each unit of column current that has been encoded by the plug in unit Whenever any information appears at the output of the Col umn Data Switch the base of 02223 is pulled more nega tive than the base of 022238 resulting in a negative LO Display Skip output to the Timer stage through Q2229 Re call that a LO was necessary at the skip input of the Timer so it could perform the compiete sequence necessary to display a character Transistors 02226 and 02227 also provide Display Skip ac tion The end of werd level connected to their emitters is LO only during time siot 1 This means they are enabled only during this time siot These transistors allow the Zeros Logic and Memory stage to generate a Display Skip signal during time siot 1 when information that is not to be dis played on the CRT has been stored in memory further in formation is given under Zeros Logic and Memory COLUMN AND ROW DECODERS The Column Decoder U2244 and Row Decoder U2185 sense the magnitude of the analog voltages at their inputs pin 10 and produce a binar
465. oltage exceeds about 80 volts Do not remove the power unit cover while this light is flashing 1 Slide out the power unit as previously described C2314 31 Figure 4 11 Power supply unit securing screws Remove the four small screws that secure the cover to the rear heatsink Remove the 9 screws that attach the sides of the cover to the power unit chassis Do not remove the four screws from the bottom of the Power Supply Unit Disconnect the two coaxial cables one 4 connector from P40 on the A12 Control Rectifier board Remove the cover from the power supply unit The power supply unit is now open for maintenance or repair H the 7904A is to be operated with the cover removed first reconnect the coaxial cables to the A12 Control Rectifier board Reverse the order of removal to replace the power unit cover Before performing maintenance or taking resistance measurements in the power supply unit manually discharge the line storage capacitors A23C16 and A23C17 as follows 1 Remove the protective cover from the power supply unit following the preceding procedure Apply a 1 5 kilohm 2 watt insulated resistor across the capacitor screws as indicated in Figure 4 5 2 CATHODE RAY TUBE REMOVAL Remove the cathode ray tube crt as follows Maintenance 7904A WARNING The crt may retain a dangerous electrical charge Before removing the crt the anode must be fully
466. onents which make up each logic function are identified An input output table for this stage is given in Figure 3 78 3 20 SWEEP CONTROLLED Z AXIS X Y X Y displays can only be obtained in conjunction with a time base unit When an amplifier unit is installed in the A B Horizontal Compartment the Z Axis is controlled by the time base unit in the B A horizontal compartment independent of the setting of the HORIZONTAL MODE switch The B A indicator lamp automatically turns on the selection of the horizontal mode by the HORIZONTAL MODE switch is not effected X Y displays often consist of a display where a fast switching transient occurs between two stable states The switching may be such that the display is predominantly in these two stable states If the Z Axis was not duty cycled but turned on permanentiy this would result in a display with two bright spots and a barely visible or invisible transient since the average screen current associated with these bright spots can be large enough to enable the intensity limiter By triggering the time base unit with the Y Axis signal the duty cycle of the Z Axis can be controlled with the time base unit time division control With the HORIZONTAL MODE switch set to ALT an X Y display alternating with a Y T display is obtained The Z Axis for both displays is on oniy during the waveform segment shown in the Y T display This is a visible aid for optimum control of the Z Axis duty cycle of
467. ontrols as follows PODS POWER 5252 rero xe e ren VERTICAL MODE a ROI RIGHT VERT TRACE SEPARATION Midrange TRIGGER SOURCE VERT MODE A INTENSITY Na acid ar lo aad TE Midrange HORIZONTAL A B INTENSITY 2 cous ed c OC D dO Midrange B TRIGGER SOURCE VERT MODE READOUT OFF in detent GRAT ILLUM Midrange Pushbutton out READOUT MODE PLUG SMS PAA a Pay T Connect pins 1 amp 2 see Test Point and Adjustment Locations G a Set the POWER switch to OFF b Move Plug P2184 to Pins 2 and 3 C Set the POWER switch to on d Set the READOUT INTENSITY control for visible char acters all zeros NOTE The following tolerances are provided as guides to correct instrument operation and are not instrument specifications 5 72 ADD NOV 1985 EXAMINE the crt display for two rows of zeros 40 zeros to a row The two rows of zeros should be cated vertically in the middle of the top and bottom divi sions of the graticule see Fig 5 4 NOTE The MVA Center Main Vertical Amplifier Adjustment 8736 must be correct before making the next adjust ment Hefer to F Vertical System procedure ADJUST Vertical Separation adjustment R2260 the A15 Readout S
468. or soldering practices between the layers the board is unusable and must be replaced Damage can void the warranty Multilayer circuit boards in the 7904A include A6 Main Interface A12 Control Rectifier A13 Logic and A14 Trigger Selector o UTION PN m um rns LON MO m Only an experienced maintenance person proficient in the use of vacuum type desoldering equipment should attempt repair of any board in this instrument When soldering on circuit boards or small wiring use only 15 pencil type soldering iron A higher wattage soldering iron can cause the etched circuit wiring to separate from the board base mater al and melt the insulation from small wiring Always keep the soldering iron tip properly tinned to ensure the best heat transfer to the solder joint Apply only enough heat to make a good solder joint To protect heat sensitive components hold the component lead with a pair of long nose pliers between the component body and the solder joint The following technique should be used to replace a component on any of the circuit boards Touch the tip of the vacuum desoldering tool directly to the solder to be removed o CAUTION Excessive heat can cause the etched circuit wiring to separate from the board base material Never allow the solder extractor to remain on the board for more than three seconds Solder wick spring actuated or squeeze bulb solder suckers and heat blocks for m
469. orizontal deflection systems The Ready signal is also derived from this output and con nected to the Character Generator stage and the two Out put Amplifier stages The Z Readout output at pin 12 is produced next This cur rent is connected to the CRT circuit to unblank the CRT to the intensity level determined by the voltage on the Readout Intensity line The Timer stage operates in one of two modes as controlled by the Display Skip level at pin 4 The basic mode just de scribed is a condition that does not occur unless all ten char acters of each word 80 characters total are displayed on the CRT Under typical conditions only a few characters are displayed in each word The Display Skip level at pin 4 de termines the period of the Timer output signal When a char acter is to be generated pin 4 is LO and the circuit operates as just described However when a character is not to be displayed level is applied to pin 4 of U2126 through CR2125 from the Display Skip Generator stage This signal causes the Timer to shorten its period of operation to about 210 microseconds The waveforms in Figure 3 13 show the operation of the Timer stage when the Display Skip condi tion occurs for all positions in a word Notice that there is no output at pins 12 13 and 14 under this condition This means that the CRT display is not interrupted to display characters Also notice that the triangle waveform at pin 6 does not go as far negative
470. ors encode two units of column current and four units of row current to cause a V volts symbol to be displayed Time slot 10 is not encoded in accordance with the Standard Readout Format The resultant CRT readout will be 100uV the above example the row analog data was pro grammed to define which row of the Character Selection Matrix was addressed to obtain information in each time slot The column data changes to encode the applicable readout data as the operating conditions change For exam ple if the variable control of the plug in unit was activated R130 would be connected between time siot 3 and the col umn analog data output line This encodes 10 units of col umn current see shaded area in time slot 3 of the waveform shown in Fig 3 16 Since one unit of row current is also encoded during this time slot by R30 a gt gt greater than symbol is added to the display The crt readout will now show gt 1004V in a similar manner the other switches can change the encoded data for the column output and thereby change the readout display See the descriptions which fol low for decoding this information The column analog data encoded by most plug in units can be modified by attenuator probes connected to the input connectors of amplifier plug in units special coding ring around the input connector of the plug in unit senses the attenuation ratio of the probe with readout encoded probes oniy The probe contains a circ
471. ose reset input is connected to the Trigger Signal from pin 5 of the Timer When the Jump Command and Trigger inputs iow U2162B produces LO output to reset the time slot Counter as well as advancing the Hori zontal Character Position Counter and the Channel Counter U2162B also produces output to signal Dis play Skip at pin 4 of the Timer ZEROS LOGIC AND MEMORY The Zeros Logic and Memory stage U2232 stores data en coded by the plug in units to provide zeros adding and pre fix shifting logic for the Readout System The Strobe pulse at pin 15 goes positive when the data has stabilized and can be inspected This activates the Zeros Logic and Memory stage so that it can store the encoded data Typical output waveforms of the five possible input condi tions that can occur are shown in Figure 3 17 When time slot 1 occurs a store command is given to all of the memories If the plug in units encoded data for column 1 2 3 4 or 10 during time siot 1 the appropriate memory or memories is set Notice that row 3 information from the Row Decoder must also be present at pin 16 for data to be stored in the memory of U2232 lf data was encoded during time slot 1 a negative going output is produced at pin 7 while the memories are being set This negative going pulse is connected to the base of 3 47 Theory of Operation 7904A Q2227 in the Display Skip Generator to produce a Display Skip output Since the informatio
472. ot performed first perform step then proceed E6 SETUP CONDITIONS 7904A Controls VERTICAL MODE B 5 55 E Test Equipment Controls Time Base Sweep Rate 1 ms div Triggering Auto AC internal Amplifier Deflection Factor 0 1 Input Coupling Signal Standardizer IN 4593 426 a Position the trace to the upper half of the graticule area with the signal standardizer Position control b Set the VERTICAL MODE switch to LEFT and position the trace to the lower half of the graticule area with the amplifier Position control c CHECK for two traces in the ALT and CHOP positions of the VERTICAL MODE switch d Set the VERTICAL MODE switch to ADD e a single trace that can be positioned vertically with either left or right vertical Position controls 5 29 Checks and 7904 Part Check E7 CHECK VERTICAL TRACE SEPARATION B OPERATION NOTE If the preceding step was not performed first perform step Ef then proceed E7 SETUP CONDITIONS 7904A Controis HORIZONTAL MODE VERTICAL MODE a m Test Equipment Controls A Time Base Sweep Rate 1 ms div Triggering Auto AC Internal B Time Base Sweep Rate Triggering Auto AC internal 4593 427 a the VERT TRACE SEPARATION B control thro
473. ow TABLE 1 4 Environmental Characteristics Characteristics T information P Temperature Operating 0 C to 50 Storage 55 to 759 Altitude Operating 15 000 ft 4 550m Storage 50 000 ft 15 200m 1 9 General information 7904A TABLE 1 4 CONT Environmental Characteristics Characteristics information EMC Electromagnetic Compatibility Meets requirements of MIL STD 461B when tested in accordance with the following test methods of MIL STD 462 All instruments CS 01 and CS 06 Does not meet CE 01 CE 03 CS 02 RE 02 T RE 04 RS 01 and RS 03 Option 3 Electromagnetic Compatibility Meets RE 02 limited to 1 GHz RS 01 and RS 03 limited to 1 GHz Vibration Tested to MIL T 28800C Sect 4 5 5 3 1 Type 111 Class 5 Style E except 0 15 inch p p amplitude Sect 4 5 5 3 1 c 55 Hz Resonance Dwell Sect 4 5 5 3 1 e 2 and 20 to 55 Hz Frequency Increment Sect 4 5 5 3 1 e 2 Bench Handling Tested to MIL T 28800C Sect 4 5 5 4 3 Type HI Class 5 Style E Tianeportation 4 Qualified under National Safe Transit Committee Test Procedure A1 Category ii Bounce NSTA Project 1 1 Drop Packaged Product NSTA Project 1 2 Drop height 24 inches 16 drops Tested to MIL STD 810C Method 507 1 Procedure IV modified as specified in MIL T 28800C paragraph 4 5 5 1 1 2 except 90 95 Relative Humidity Steps 5 and 6 Operating tests at 50 C Step 5 second
474. ow and Column Decimai to BCD Converters remain the same until the character is com plete However the Lower Order Address Generator keeps counting and combines with the Row and Column Decimal to BCD Converter s outputs to address the EPROM lo cations necessary to form the readout character Suppose the next address produces a Character Generator output of 01111010 or 172 The octal digit 1 indi cates binary bit 7 is high which will turn on Q2132 and the Z Readout output to the instrument The instrument will now provide a trace from the previous vertical and horizontal co ordinates to the new ones vertical 7 and horizontal 2 Thus the character is formed by a series of binary words causing the instrument CRT beam to move or draw between points HORIZONTAL CHARACTER POSITION COUNTER The Horizontal Character Position Counter U2202A is 4 bit binary counter Its output is converted to current by R2266 through R2269 and added to the X horizontal signal for spacing readout characters horizontally on the CRT The counter is reset to 0000 with a Word Trigger pulse from U2127B and is advanced with inputs from two possible 3 50 sources The first is a HI End of Character signal from pin 19 of U2204 The counter can aiso be advanced when Space instruction is encoded by the plug in unit to cause a space to be left between two characters on the CRT A Space instruction occurs when row 10 from the Row De cod
475. owing the procedure given under Access to Components in the Power Supply Unit 2 Replace the line fuse 3 Check diode bridge CR15 on the A23 Power Supply inverter board and the associated line input circuit for a shorted components If the circuit appears normal connect the power cord to the variable autotransformer 4 Attach the test probe from the digital multimeter to one of the screws used to discharge C16 and C17 see Fig 4 5 Connect the other test lead to ground Set the variable autotransformer for 20 volts and turn the 7904A on 1 5K0 2W Resistor insulated oo Partial A23 inverter Board C2874 205 Figure 4 5 Location of screws for discharging line storage capacitors 4 11 Maintenance 7904A 5 Check for a dc voltage on the digital multimeter of approximately 27 volts Move the test probe to the other capacitor screw Check for a dc voltage which is both equal and opposite in polarity from the previous voltage This checks the condition of the line storage capacitors Step E Check CRT and High Voltage Circuit To check the crt circuitry perform the following procedure 1 Disconnect the 7904 from the power source and discharge the line storage capacitors following the procedure given under Access to Components in the Power Supply Unit Remove multi lead cable P40 from the A12 Control Rectifier board Set the variable autotransformer for 115 volts Connect the 7904A power cord pl
476. p G1 then proceed G4 SETUP CONDITIONS 7904A Controls No change in settings 8 amp E 4 Test Equipment Controls Amplifier Dispiay Mode Dual trace 4593 547 a Press and hold one of the amplifier trace identify buitons b EXAMINE the readout display for correct indication of IDENTIFY If the readout display is incorrect adjustment is required ADJUST Column Match adjustment R2214 and Row Match adjustment R2183 on the A15 Readout System Board for correct readout of IDENTIFY Set these adjustments to the center of the range which provides correct readout indication Release the amplifier trace identify button REV JAN 1987 Checks and Adjustment 7904A Part ii Adjustment and Performance Check G5 CHECK READOUT MODES NOTE If the preceding step was not performed first perform step G1 then proceed G5 SETUP CONDITIONS 7904A Controls HORIZONTAL MODE amp ER t2 lt 5 Test Equipment Controis Time Base Sweep Rate Triggering Auto AC Internai 4593 548 a Set the READOUT INTENSITY control for a visible display b CHECK set the time base to several sweep rates throughout its range and check that the readout characters are displayed c Set the READOUT GATE EXT button to GATE pressed in and set the READOUT INTENSITY control to PULSED d Set the GATE mode switch to A e Set the READOUT PRESET control for a visible
477. pansion anywhere within the c ADJUST Vert Gain adjustment R211 on the A18 graticule area Vertical Amplifier Board for one division between each of the center seven displayed traces within INTERACTION if the specification of part b was 0 05 division not met perform steps F2 F3 F5 and F6 d Remove the signal standardizer from the RIGHT VERT compartment and install it in the LEFT VERT compartment Set the VERTICAL MODE switch to LEFT f CHECK for one trace per graticule division within 0 05 division of the error noted in part b over the center 6 graticule divisions g ADJUST if necessary Vert Gain adjustment R211 for the best compromise for gain in both LEFT and RIGHT compartments 5 62 F5 ADJUST THERMAL COMPENSATIONS A18R130 A18C200 A18R238 A18R335 A18R237 A18R132 A18R131 NOTE If the preceding step was not performed first perform step F1 then proceed F5 SETUP CONDITIONS 7904A Controls A TRIGGER SOURCE RIGHT VERT i _ amp 89 oS 7 E e Time Test Equipment Controls Time Base Sweep Rate Triggering 10 us div Auto AC Internal Signal Standardizer Rep Rate a Set the signal standardizer Position and Amplitude controls for an eight division display centered on the crt b Set the VERTICAL MODE switch to CHOP Set the READOUT INTENSITY control for a visible readout display Checks and Adjustment 7904A Part li Adjus
478. pe display of six divisions of deflection between the center seven traces within 0 6 division 300 millivolts within 30 millivolts Remove the signal standardizer from the LEFT VEHT compartment Set the test oscilloscope to alternate between channel 1 and channel 2 Re establish a ground reference for both channels of the test oscilloscope Then set both channels for dc coupling test oscilloscope display for a dc level within 1 division 50 millivolts of the established ground reference ADJUST the DC Common Mode adjustment H279 on the A14 Trigger Selector Board for a dc level within 1 division of ground 5 51 Checks and Adjustment 7904A Part H Adjustment and Performance Check D3 ADJUST B TRIGGER SELECTOR CENTERING AND GAIN A14R455 A14R474 A14R479 NOTE If the preceding step was not performed first perform step D1 then proceed D3 SETUP CONDITIONS Test Oscilloscope 7904A Controls No change in settings Ws Gosxiaj Cables Test Equipment Controls Test Oscilloscope Vertical Deflection Channel 1 50 mV div input Coupling Gnd or Off Channel 2 50 mV div input Coupling Gnd or OH Sweep Rate 1 ms div 4593 519 a Set the test oscilloscope for differential operation between the two channels added display mode with one channel inverted b Establish a ground reference levei for the test oscilloscope by positioning the trace to the center horizontal li
479. pin 15 of U2159 the Time Slot Counter returns to the normal sequence of operation and produces an output on the time slot 1 line CHANNEL COUNTER Channel Counter U2250 is a binary counter that produces the Channel Address Code for the Column and Row Decoder stages and the Format Generator stage This code instructs these stages to sequentially select and display the 8 channels of data from the plug ins Table 3 12 gives the 8 combinations of the Channel Address Code and the resuitant channel selected with each combination TABLE 3 12 Channel Address Code SN B031766 amp Below Pin 11 Pin 8 Pin 9 Channel 12250 02250 92250 Displayed LO LO LO Channel 2 Left Vertical LO LO HI Channel 1 Left Vertical LO LO Channel 2 Right Vertical LO HI Channel 1 Right Vertical HI LO LO Channel 2 A Horizontal HI LO Hi Channel 1 A Horizontal HI LO Channel 2 B Horizontal HI HI HI Channel 1 B Horizontal 3 30 SINGLE SHOT LOCKOUT The Single Shot Lockout stage allows a single readout frame 8 complete words to be displayed on the crt after which the Readout System is locked out so further readout displays are not presented until the circuit is reset Integrated circuit U2120C and U2120B connected to form a bistable flip flop For free run operation pin 8 of U2120C is held HI This activates U2120C and results in a LO output level at pin 10 enabling the Timer stage to operate in a free running manner The output of th
480. pply Regulator through C119 and R119 The Cathode Supply Regulator consists of a noninverting preamplifier U123 and an inverting output amplifier Q129 The 50 volt supply connected to pin 3 of U123 through HV ADJ R115 in conjunction with the ground connected to pin 2 of 0123 through R122 provide the reference for error amplifier U123 Transistor Q129 is connected as an inverting amplifier driven by U123 to provide error correction to the crt cathode supply Regulation occurs as follows If the crt cathode voltage becomes less negative a positive going change is coupled to the input of U123 at pin 3 and results in a positive going output at pin 6 This positive going change is inverted by Q129 to a negative going change at its collector This causes the voltage across C82 to increase during the positive half cycle of the input waveform During the negative half cycle the increased voltage across C82 increases the voltage at the output of the CRT Cathode Supply to correct the original error High frequency correction signals are ac coupled to the crt cathode through C89 CONTROL GRID DC RESTORER The Control Grid DC Restorer stage elevates the dc level of the Z Axis Amplifier output to a potential more negative than the crt cathode This action allows the control grid to control the crt beam current The Controi Grid DC Restorer stage is driven by the square wave output of T14 pin 9 Diodes CR64 and CR63 are 3 58 forward biased
481. r Geometry CRT Characteristics Minimum Photographic Writing Speed with out film fogging Standard crt Option 4 Option 13 Option 78 Exposure Defects p TABLE 5 2 CONT Performance Check Summary DISPLAY internal illuminated with variable edge lighting Eight divisions vertical by ten divisions horizontal Each division equals one centimeter Eight divisions vertical by ten divisions horizontal Each division equals 0 5 centimeter P31 11 Limits display within graticule area when actuated Within 0 1 division checked over entire 8 x 10 division graticuie area Test Conditions TEKTRONIX C 51 camera with lens set at 1 2 1 0 5 Object to Image Ratio Polaroid 20 000 ASA film Phosphor aui 2 cm ns 4 cm ns 2 5 cm ns 1 With Intensity and Graticule illumination controls fully counterclockwise open the camera shutter for 5 minutes Resulting print must be completely black A2 Check Geometry Part I Pari il Performance Performance Check Adjustment and Requirements Procedure Title Performance Procedure Title Does not normally require customer verification Satisfactory operation substantiated at factory Checked in the Operators Checkout Procedure in Section 2 87 Adjust Trace Alignment Geometry and Focus Does not normally require customer verification Satisf
482. r 5 59 Checks and Adiustment 7904A Part Hi Adiustment and Performance Check EB CHECK ADJUST X Y DELAY e Set both Internal Delay Disable switches S801 and COMPENSATION A17C804 A17C814 S811 on the A17 X Y Delay Compensation Board NOTE to the in up position If the preceding step was not performed first f Set the low frequency sine wave generator to perform step E1 then proceed produce eight divisions of vertical and horizontal deflection at 1 MHz SETUP CONDITIONS ee 0 CHECK the crt display for a Lissajous pattern with a separation of 0 28 division or less indicates 2 or less phase shift see Figure 5 3 7904A Controls h ADJUST X Y Comp adjustment C814 on the A17 X Y Delay Compensation Board for minimum separation of the display see Figure 5 3 Low Frequency YT Sine Wave i Remove the amplifier from the B HORIZ Generator compartment and install it in the A HORIZ compartment leave signal connected 5 5 5 5 5 j Set the HORIZONTAL MODE to A Acci CHECK the crt display for a Lissajous pattern with Connector BNC T Connector a separation of 0 28 division or less indicates 2 or naidi less phase shift see Figure 5 3 Test Equipment Controls L ADJUST X Y Comp adjustment C804 on the A17 Amplifier Units X Y Delay Compensation Board for minimum Volts Div 7 Coupling separation of display see Figure 5 3 m Set both Internal Delay Disable swit
483. r a body of the text identify front panel controls complete performance check or adjustment of the indicators and connectors on the 7904A instrument e g READOUT Initial capitals identify controls indicators and connectors e g Each step contains the Setup Conditions which if Position on associated test equipment used applicable include control settings for this instrument a in this procedure and adjustments internal test setup illustration and test equipment control to the 7904A e g Vert Gain settings The Setup Conditions are written so that if 5 1 Checks and Adjustment 7904A desired each subsection A B C etc A1 A2 B1 B2 etc can be performed separately A heading system is provided to readily identify the steps A1 A2 B1 B2 etc that contain performance check and or adjustment instructions For example if CHECK is the first word in the title of a step an electrical specification is checked If ADJUST is the first word in the title the step concerns one or more internal adjustments And if CHECK ADJUST appears in the title the step involves electrical specification checks and related adjustments EXAMINE is the first word in the step title the step concems measurement limits that indicate whether the instrument is operating properly these limits are not to be interpreted as electrical specifications step The alphabetical instructions under each step a b c etc may contain CHECK EXAM
484. r before removing protective panels soldering or replacing components CRT HANDLING Use care when handling a crt Breakage of the crt causes a high velocity scattering of glass fragments implosion Protective clothing and safety glasses should be worn Avoid striking the crt on any object which might cause it to crack or implode When storing a crt place it in a protective carton or set it face down in a protected location on a smooth surface with a soft mat under the faceplate USE THE PROPER FUSE To avoid fire hazard use only the fuse specified in the parts list for your product and which is identical in type voltage rating and current rating Section 3 7904 This section describes the circuitry used the 7904 Oscilloscope The description begins with a discussion of the instrument using the block diagram shown in Figure 3 1 and continues in detail showing the relationships between the stages in each major circuit Schematics of all major circuits are given in Section 8 Diagrams and Circuit Board Hlustrations Stages are outlined on the schematics with wide shaded lines Stage names in shaded boxes Refer to these schematics throughout the following circuit description for specific electrical values and relationships BLOCK DIAGRAM The following discussion is provided to assist in understanding the overall concept of the 7904A Oscilloscope mainframe
485. r panel a Connect the precision dc voltmeter DVM between TP126 located on the 12 Control Rectifier Board and chassis ground Access to TP126 is through the A12R93 Pre Reg Adj hole marked R1293 on the panel in the bottom of the power supply unit b EXAMINE the meter for a reading of 108 volts within the limits of 107 5 to 108 5 volts if the meter reading is within the given tolerance proceed to step ADJUST Pre Reg Adj R93 marked R1293 on the panel and located on the A12 Control Rectifier Board for a meter reading of 108 volts d INTERACTION any change in the setting of R93 may affect the adjustment of R15 given in step A3 5 35 Checks and Adjustment 7904A Part H Adjustment and Performance Check ADJUST 50 VOLT POWER SUPPLY NOTE A22R15 The Power Supply voltages can be checked NOTE without removing the power unit by using a rigid 7000 series plug in extender Refer to Table 5 3 Test Equipment If the preceding step was not performed first perform step A1 then proceed a Set the POWER switch to OFF and disconnect the A3 SETUP CONDITIONS line cord from the power source Remove any plug 7904A Controis in units from the plug in compartments Expose the No change in settings 7904A power supply adjustments and test points by removing the power unit from the rear of the 7904A interconnecting cables remain connected See the Maintenance section in this manual for power
486. ransistor is off The A INTENSITY control sets the output current level when the Gate at pin 14 U4485 is and the Display B Command connected to pin 15 through Q4488 and Q4492 is LO The A Intensity current is blocked whenever the A Gate level goes LO indicating that the sweep is complete or the Display B Command goes indicating that the B sweep is being displayed The current from the A INTENSITY control is connected to pin 16 through R4482 the delayed mode current is added to the INTENSITY current during the A sweep time to intensify a portion of the trace This intensified portion is coincident with the B sweep time indicating which portion of the A sweep is displayed in the delayed mode The A Intensified current is supplied to pin 2 of 04485 from the INTENSITY control through 04480 amp 4481 With this configuration the intensified current increases as the A INTENSITY control setting is advanced This provides a proportional intensity increase in the intensified zone as the overall A sweep intensity increases Therefore the intensified zone is more readily visible at high intensity levels A front panel screwdriver adjustment B CONTRAST R2015 sets optimum contrast between the intensified portion and the overall sweep The intensified current is added to the A INTENSITY current producing an intensified zone on Theory of Operation 7904A the A sweep under the following conditions HI A
487. ration and capabilities of the instrument Familiarization begins with installation instructions followed by a brief description of all controls connectors and indicators Next an Operators Checkout Procedure checks basic instrument operation and provides procedural familiarization Detailed Operating Instructions and Applications convey the more complex details of 7904A operation For detailed information for specific plug in units used with the 7904A refer to the manuals for that unit WARNING To avoid electric shock hazard see Installation in the General Information section of this manual before operating th s instrument PLUG IN UNITS The 7904A accepts up to four Tektronix 7000 series plug in units allowing selection of bandwidth sensitivity display mode etc and provides for future expansion of the system Refer to Tables 1 7 through 1 9 in the General Information section The overall capabilities of the system are mainly determined by the characteristics of the selected plug ins Some typical combinations are given under Applications in this section along with simplified set up instructions For information on other plug in units refer to the current Tektronix Products catalog INSTALLATION OF PLUG IN UNITS CF T NUT CAUTION WIS a ae To prevent instrument damage plug in units should not be installed or removed without first turning the instrument power off To install a plug in unit int
488. rator 1 kHz Repetition Rate 1 kHz within 0 2596 Satisfactory operation substantiated at factory C2 Check Adjust Calibrator Output Voltage C3 Check Adjust Calibrator 1 kHz Repetition Rate C4 Check Calibrator Rise Time Fall Time and Duty 49 8 10 50 2 B4 Check Calibrator Rise Time Fall Time and Duty Cycle Cycle Rise Time and Fall Time 900 ns or less into 100 pF oriess SIGNAL OUTPUTS ELE SAWTOOTH Source Selected by front panel switch B5 Check A and B Sawtooth Output Voltage Rate of Rise Into 500 Into 1 Polarity i HORIZ time base unit J 5A A A A AA A Output Signais B B HORIZ time base unit Positive going with baseline at 0 V within 1 V into 1 50 mV unit of time selected by time base unit time div Switch within 15 100 ns div maximum sweep rate 1 V unit of time selected by time base unit time div switch within 10 1 us div maximum sweep rate B6 Check and B Gate Output Signals Output Signals Selected by front panel switch A Gate derived from HORIZ time base unit main gate B B Gate derived from B HORIZ time base unit main gate Positive going with baseline at O V within 1 0 V into 1 MQ C5 Check A
489. re connected to the plug in unit However time slots 5 6 and 10 are not used by the plug in unit to encode data when using the Standard Readout Format See Table 3 11 for Standard Readout Format The amplitude of the time siot pulse is exactly 15 volts as determined by the Timer stage Therefore the resultant output current from the piug in units can be accurately controlled by the pro gramming resistors in the plug in units For example in Figure 3 15 resistors R10 through R90 con troi the row analog data which is connected back to the Headout System Figure 3 16 shows an idealized output current waveform of row analog data resulting from the time slot pulses Each of the row current levels shown in these waveforms correspond to 100 microamperes of cur rent The row numbers on the left hand side of the wave form correspond to the rows in the Character Selection Matrix see Fig 3 20 The row analog data 15 connected back to the Readout System via terminal B37 of the plug in interface The column analog data is defined by resistors R110 through R190 The program resistors are connected to the time slot lines by switch closures to encode the desired data The data as encoded by the circuit shown in Figure 3 15 indicates 100 microvoit sensitivity with the CRT dis play showing inverted and calibrated deflection factors This results in the idealized output current waveforms shown in Figure 3 16 at the column analog data output
490. red to keep the output level at 8 5 volts VERTICAL CHANNEL SELECTOR The Vertical Channel Selector interfaces the Channel Switch 0568 to the logic signals arriving from the Main Interface The Channel Switch stage requires two pairs of complementing control voltages one pair for each channel The HI control voltage is 40 V the complementing LO voitage is 3 5 V To select a channel the level must be applied to the On input of U668 pin 2 for LEFT and pin 12 for RIGHT VERTICAL MODE switch positions and the LO level must appear at the OFF input pin 1 for LEFT and pin 11 for RIGHT VERTICAL MODE switch positions To inhibit a channel the control voltages should be reversed When the VERTICAL MODE switch is set to LEFT the Display Right iine entering on P680 pin 6 is set LO 0 6 V the Add line P680 pin 5 is LO 0 V and normally X Y inhibit is LO 0 6 V Transistors Q652 Q658 and Q558 are turned on Q656 and Q556 are off The resuit is pins 1 and 12 of U668 are pulled down to 8 5 V but pins 2 and 11 are oniy pulled down to 4 0 V Consequently the LEFT VERT channel is turned on while the RIGHT VERT channel is turned off Signals ADD NOV 1985 appearing at J602 J603 are amplified and fed to the outputs at 4592 and J694 Similarly if Display Right is HI 1 V the RIGHT VERT channel is turned on and LEFT VERT channel off RIGHT VERT channel signals amplified and fed to the outputs LEFT VERT channel
491. regulated 54 volt supply by reference zener diode VR36 and emitter follower Q38 REV JAN 1987 Theory of Operation 7904A 3 The 5 6 volt supply is generated from the semi regulated 17 volt supply by zener diode VR152 4 The 5 6 volt supply is generated from the semi regulated 17 volt supply by zener diode VR156 50 V REGULATOR Semi regulated 54 volts from the Converter Rectifiers circuit diagram 14 provides the unregulated voltage source for this supply Differentia amplifier U15 compares the feedback voltage at pin 2 against the reference voitage at pin 3 The error output at pin 6 of 015 reflects a difference between these two inputs Zener diode VR12 sets a reference level of about 9 volts at pin 3 of U15 A sample of the output voltage from the 50 volt supply is connected to pin 2 of U15 through divider network R16 R15 and R14 Variable resistor R15 in this divider sets the output level of this supply Notice that the feedback voltage of this divider is obtained from a line labeled 50 VS sense If the feedback voltages were obtained at the supply the voltage at the load would not stay constant due to the inherent resistance of the interconnecting cable between the supply and its load The sense configuration overcomes this problem by sensing the voltage at the load Since the current in the sense line is small and constant the load voltage is held constant regardiess of the load current Regulation of vol
492. rent is added to the column analog data during time slot 1 Since two units of current were encoded by R111 this additional current results in a total of three units of column analog current during this time slot Referring to the Character Selection Matrix three units of column current along with the two units of row current encoded by R10 indicates that the prefix should be shifted one column to the left Since this instruction occurs in the same time slot that previously indicated that two zeros should be added to the display and only one instruction can be encoded during a time siot the zeros do not appear in the display The crt readout will now be changed to 1 2 ROWN 71214314 15 16 17 8 9 10 TIME SLOT e we ARE 131 d 8 29 70 PROGRAM FOR 100 uV INVERTED CALIBRATED UNCALIB RATED OPERATION SHOWN BY SHADED AREA C1 195 34 Figure 3 16 idealized current waveforms of Row analog data and Column analog data mV readout program produced by plug in same as for previous example Three other lines of information are connected from the plug in compartments to the Readout System The column and row analog data from channel 2 of a dual channel piug in are connected to the Headout System through terminals A38 and B38 of the plug in interface respectively Force readout information is encoded on terminal A35 the function of this input is described under Column and Row Data Swi
493. rews securing the crt bezel to the front panel Remove the bezel and disconnect the three pin camera power connector from the rear of the bezel Remove the plastic faceplate protector the graticule light assembly and the black crt faceplate mask The graticule light assembly need not be unsoldered from its leads Hold one hand on the crt faceplate and gently push forward on the crt base with the other Slowly pull 4 17 Maintenance 7904A the crt out from the front of the instrument while guiding the crt anode lead through the holes in the crt shield CATHODE RAY TUBE REPLACEMENT Heplace the cathode ray tube crt as follows 1 Insert the crt into the shield guiding the crt anode plug through the holes in the crt shield Set the crt firmly against the front pane casting 2 Clean the crt faceplate piastic faceplate protector and the light filter with denatured alcohol 3 Place the black crt mask over the faceplate Reconnect the multi pin connector to the crt bezel align the arrow on the connector with the arrow on the bezel 4 Hold the faceplate protector in position and replace the crt bezel graticule light assembly light filter frame and light filter Firmly tighten the four screws making sure that the light filter is properly aligned 5 Gently push forward on the crt base to ascertain that the crt is as far forward as possible Then tighten the two screws beside the crt base until the springs
494. riggering Auto AC internal BNC T Connector Coaxial Cabie Test Equipment Controls Amplifier Unit Deflection Factor Signal Standardizer 0 5 V div estere Vert or Horiz Step Resp Time Base Sweep Rate 20 us div Triggerin Precision Dc Voltmeter DVM AIO AG 4593 511 a Set the low frequency sine wave generator for 4 a Connect the precision dc voltmeter DVM between division display at 50 kilohertz one volt above and TP83 on the A21 Z Axis Board and ground below ground b Set the signal standardizer Amplitude and Position b Set the A INTENSITY control for a dim display controls for a 3 division square wave centered on the crt c Connect the signal from the output of the bnc T connector at the amplifier input to the Z AXIS Set the time base Triggering controis for a stable INPUT connector on the rear panel with a coaxial display triggered on the rising edge cable d EXAMINE ihe crt display for objectionable d EXAMINE the positive portion of the displayed defocusing of the crt display waveform is blanked e ADJUST the Focus Gain adjustment R63 on the A21 Z Axis Board for optimum focusing of the high intensity trace f EXAMINE the voltmeter for a reading greater than more positive 12 volts g ADJUST if optimum focus of trace occurs below more negative 12 volts compromise the setting of R63 until voltm
495. rizontal Z Axis and Auto Focus Amplifiers provide all quiescent potentials and signal information necessary for a properly displayed crt trace The schematic diagram of the High Voltage Power Supply and CRT circuits is given on diagram 13 in Section 8 Diagrams and Circuit Board Illustrations The schematic is divided by gray shaded lines separating the circuitry into major stages Sub headings in the following discussion use these stage names to aid in locating and identifying the components and portions of the circuitry described POWER TRANSFORMER The Power Transformer 14 is driven by a 25 KHz square wave voitage from the Converter Rectifiers circuit secondary of Low Voltage Transformer T110 on diagram 14 Three secondary windings on 14 provide power for the 130 V Supply CRT Heater voltage Anode Voltage Multiplier and the CRT Cathode supply The square wave output of T14 also drives the Controi Grid DC Restorer and the Focus Grid DC Restorer stages through the resistor pairs R61 R62 and R31 R32 respectively The Fauit Sense output referenced to ground in the transformer secondary through CR17 CR18 CR19 is connected to the Inverter control circuit diagram 14 130 V SUPPLY The 130 V Supply provides a semi regulated voltage for use in several circuits in the 7904A Semi regulation is achieved by the inverter Control stage of the Converter Rectifiers circuit diagram 14 Diodes CR101 and CH102 rectify the voltage fro
496. rmation this pulse goes LO This erases the four memories in the Zeros Logic and Memory in preparation for the data to be received from the next channel CHARACTER GENERATOR Each character to be displayed on the instrument CRT con sists of a series of connecting points developed on a possi ble 8 point by 8 point grid see Fig 3 22 The 8 bit binary output from the Character Generator is used to determine the location of points within the grid whether or not to pro vide a trace connecting two points and the point at which a character has been completed The Character Generator Stage consists of an oscillator the Lower Order Address Generator and an EPROM connected to a latch Q2151 and Q2152 form a square wave oscillator whose fre quency is adjustable with C2155 to provide 16 cycles within the time allotted for developing a character The base of Q2152 goes LO when the Timer produces a negative going Ready pulse at pin 13 This starts the oscillator by turning Q2152 on The emitter of Q2151 becomes more negative as C2154 and C2155 discharge through R2154 The capac itors continue to discharge until the emitter base junction of Q2151 becomes forward biased Q2151 then begins to con duct and causes the oscillator to begin changing states As Q2151 conducts the discharge through C2154 and C2155 stops and causes a collector current reduction in Q2152 The current reduction causes the emitter and base of Q2152 to rise positive which pu
497. rmination of the delay line FEEDBESIDE The function of the Feedbeside stage is to compensate for low frequency imperfections in the frequency response of the Output Amplifier stage U415 and U515 Self heating of the transistor base emitter junction in some transistors within 0415 and 0515 cause the iow frequency gain to appear larger than the midband gain To correct this a portion of the input signal is picked off via the Delay Line Compensation stage and applied to 0335 The paraphase signal is converted to a single ended signal by U335 and distributed into six RC resistive capacitative networks each having a different time constant Resistors R130 R131 R132 R237 R335 3 53 Theory of Operation 7904A R238 and C200 are adjusted to provide an accumulated waveform This waveform is converted to a paraphase signal by 17100 0400 and 9303 and is then injected into U415 through Pins 1 and 5 where it is subtracted from the signal entering U415 at pins 7 and 9 Proper adjustment of the seven RC components results in a flat frequency response and optimum transient response at the output of U415 pins 17 and 19 Diodes CR334 and CR333 improve the vertical amplifier overdrive recovery by limiting the amplitude of the feedbeside correction signals that exceed the dynamic range of the Output Amplifier Thermistor RT303 adjusts the gain of the feedbeside amplifier to provide increased correction at high ambient temperature wher
498. rned on C42 in the inverter Start network is prevented from charging and from firing Q30 thus preventing the Inverter from starting Transistors Q45 and Q43 continue to conduct until C43 has discharged sufficiently through R45 to turn Q45 off At this point Q43 and Q46 will turn off and the Inverter will start on the next positive half cycle of the line INVERTER CONTROL The Inverter Control stage made up of primarily of U75 provides pre regulation and fault protection functions For pre regulation purposes U75 varies the hold off time Ts in Fig 3 24B of the Inverter switching transistors Under normal operating conditions only the voltage sense E Sense input at pin 15 controls the hold off time However various fault conditions can affect hold off time or stop the Inverter operation altogether The operation of individual functions of the Inverter Control stage is described the following discussion Pre Regulator The pre regulator operation of U75 maintains constant voltage at the outputs of the Low Voltage Rectifiers stage it also provides constant peak to peak voltage to the High Voltage Power Supply and CRT circuit diagram 13 Transformer T35 provides Inverter phase information and power to U75 The phase information is connected to pins 10 and 11 through C77 and C78 Bridge rectifier CR73 CR74 CR76 and CR75 provides positive and negative operating voltages to U75 A shunt regulator in U75 maintains
499. rom pin 4 of 94320 The Horizontal Chopped Blanking Inhibit signal is connected to 04485 from pin 4 of U4340 through LR4338 Q4336 and CR4471 Notice that this signal is connected to the collector of Q4336 This transistor is normally operating in the saturated condition and the Horizontal Chopped Blanking Inhibit level from U4340 is the collector source voltage When the Horizontal Chopped Blanking Inhibit level goes LO the current through Q4336 drops producing a corresponding LO level at its emitter This level is connected to pins 6 and 7 of U4485 through CR4471 Transistor Q4336 aiso controls the levels at pins 6 and 7 for readout displays The Z Axis Inhibit from the Readout System is connected to the base of Q4336 through VR4334 and 4335 This level is normally HI so Q4338 operates as controlled by the Horizontal Chopped Blanking inhibit level at its collector When a readout display is to be presented the Z Axis Inhibit level drops LO and is coupled to the base of Q4336 through 4334 Transistor Q4336 is then reverse biased producing a LO level at its emitter This level coupled to pins 6 and 7 of U4485 through CR4471 blocks the Z Axis Logic output current during the readout display The intensity of the readout display is determined by separate Readout intensity level connected directly to the Z Axis Amplifier see CRT Be Circuit description Diode CR4472 clamps the emitter of Q4336 at about 0 6 volt when the t
500. ronix Part No 317 0100 00 321 0126 00 321 0066 00 321 0193 00 315 0101 00 321 0126 00 321 0206 00 315 0272 00 323 0275 00 311 1263 00 321 0126 00 315 0102 00 315 0200 00 321 0126 00 321 0206 00 315 0101 00 315 0561 00 311 1260 00 315 0271 00 315 0152 00 311 0622 00 311 0622 00 315 0105 00 315 0101 00 315 0681 00 315 0391 00 315 0361 00 315 0302 00 303 0432 00 321 0347 00 321 0369 00 315 0510 00 301 0472 00 301 0472 00 323 0356 00 321 0260 00 321 0097 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 131 1436 00 136 0333 00 Serial Assembly No Effective _ Dscont 8010100 8010100 8010100 8010100 8010100 8010100 8021637 B021637 B021636 8021536 8021636 8021636 8021636 B021636 Replaceable Electrical Parts 79044 Name amp Description RES FXD CMPSN 10 5 0 125 RES FTLM 200 OHM 1 0 125wW TC TO RES FILM 47 5 OHM 0 5 0 125W TC TO RES FILM 1K OHM 1 0 125W TC T0 RES FILM 100 OHM 54 0 25W RES FXD FILM 200 OHM 1 0 125W TC TO RES FILM 1 37K 1 0 125W TC TO RES FXD FILM 2 7K OHM 5 0 25W RES FXD FILM 7 15K OHM 17 0 50 TC TO RES VAR NONW 1K OHM 1076 0 50W RES FILM 200 QHM 176 0 125W TC TO RES FXO FILM 1K OHM 55 0 25W RES FXD FILM 20 OHM 55 0 25M RES FXD FILM 200 1 0 125 10 RES FXD FILM 1 37K OHM 125
501. rse of the Display command level at pin 8 Q4364 establishes the Display B Command level Also notice the line connected to pin 4 of the Vertical Binary 04368 The level at pin 4 Horiz Slave Enable is established by Q4424 and is HI only when the HORIZONTAL MODE switch is set for ALT or CHOP and the time base units are nondelayed operation The Vertical Binary IC uses the information at pin 4 for correct slaving of the Vertical Alternate Command to the Display B Command necessary for independent pairs operation Horizontal Slave Enable is also used by the trigger select logic The operation of the Vertical Binary stage in relation to the modes of operation that can occur is described in the following 1 A OR B MODE When the HORIZONTAL MODE switch is set to either A or B the Vertical Alternate Command switches to the opposite state each time an Alternate Pulse is received from the Horizontal Logic stage Repetition rate of the Vertical Alternate Command in this mode is one half the repetition rate of the Alternate Pulse The input conditions for these modes are Pin 1 LO Alternate Pulse generated by Horizontal Logic stage goes negative Theory of Operation 7904A Pin 4 Horizontal Slave Enabie LO HORIZONTAL MODE switch in any position except ALT or CHOP or the A time base unit is set for delayed sweep Pin 10 HI HORIZONTAL MODE switch set to A or B 2 ALT OR CHOP MODE HORIZ NONDELAYED the AL
502. rther identify portions of the circuitry on diagram 9 The Vertical Amplifier circuit provides final amplification for the vertical signal received from delay line DLS before it is applied to the crt vertical deflector addition low frequency signals to provide the VERT TRACE SEPARATION 8 function and crt scale factor readout are accepted at the Aux Y Axis and Y Readout inputs respectively The vertical portion of the BEAMFINDER function is also handied in the Vertical Amplifier DELAY LINE Delay line DL5 delays the vertical signal approximately 65 nanoseconds to allow the horizontal circuits time to initiate a sweep before the vertical signal reaches the crt vertical deflection plates This allows the instrument to display the leading edge of the signal originating the trigger pulse when using internal triggering The delay line impedance is 100 ohms differentially and because it is coaxial does not produce preshoot or phase distortion in the crt display DELAY LINE COMPENSATION The Delay Line compensation stage provides frequency compensation to offset delay line losses due to skin effect in the cable This compensation is achieved by attenuating the signal at low frequencies approximately 4 8 dB At high frequencies about 1 0 gigahertz the signal passes with little attenuation Transient response front corner adjustment is achieved by C215 and R215 The components connecting the input signal to 0415 provide forward te
503. s nonconductive contaminants may remain on or near the contact interfaces 4 23 Maintenance 7904A 8 4 SCREW WASHER 55 4 PLASTIC FRAME ELASTOMER CONTACT HOLDER CONTACTS REGISTRATION PINS PC BOARD METAL SHEET EXPLODED VIEW OF HYPCON CONNECTOR PLASTIC FRAME CONDUCTOR ae BOARD HYBRID SUBSTRATE UNMATED FLUSH HYPCON x EI HYBRID SUBSTRATE Vat BOARD SS ar ah E STEPPED C2316 23 Figure 4 14 HYPCON assembly removal and replacement 4 24 Maintenance 7904A DISASSEMBLY AND REMOVAL Note index on circuit board arrow triangle or dot and HYPCON plastic frame pointed mounting ear Unscrew and remove the 4 screw washer assemblies Where the HYPCON connector serves to heatsink the hybrid to the chassis 2 of the 4 screws are longer Note the location of the yellow tinted screws for proper replacement 3 Lift HYPCON connector from board 4 Note index location of hybrid and remove from board with tweezers Note index location of elastomer contact holder and remove by grasping a corner of the contact holder with tweezers and lifting up Do not touch the gold plated contacts with your fingers REASSEMBLY AND REPLACEMENT Grasp corner of elastomer contact ho
504. s through the RIGHT VERT 7511 to reach the A HORIZ time base unit The 7S14 is a dual channel sampling unit with delaying sweep capabiity It must be used in the middle two plug in compartments Dual trace sampling displays can also be made by 7512 in the middle two compartments and a 7511 in LEFT VEHT compartment this application the 7512 supplies the time base for both traces X Y Sampling One 7511 inserted in the RIGHT compartment and one in the adjacent A HORIZ compartment automatically share a 50 kilohertz free running strobe condition specified for X Y displays The 7514 has an X Y operation incorporated as one of its normal mode functions SPECIAL PURPOSE PLUG IN UNITS The variety of special purpose plug in units available allows the 7904 Oscilloscope to be used for many specialized applications The following is brief discussion of some of the available special purpose plug in units Digital Counters and Multimeter Plug In Units The digital multimeter plug in units measure current voltage temperature and resistance digital frequency counter plug in units measure frequency from dc to above 500 megaheriz These units make use of the readout system to display the measured information on the crt and can function in any compartment in combination with each other or with any other plug in units available for use with the 7904A oscilloscope system The ability of digital rea
505. s carry half of the input signal from the power dividers to the and B Trigger Selector circuits The inputs of the channel switches U232 13432 have a 50 ohm input impedance and terminate the transmission lines Trigger Channel Switch Channel switch U232 has two differential inputs and one differential output Control voltages at pins 1 2 11 and 12 determine whether the input signals are terminated within the channel switch or are coupled through to tne output Active components U252A and Q254 keep the output dc common mode voltage on pin 3 and pin 13 at 3 2 volts for modes of the channel switch U232 The dc common voltage is sensed by resistors R237 and R247 and is compared with a 3 2 volt reference set by divider R251 and R252 If resistors R237 and R247 sense a voltage higher than 3 2 volts the output of U252A goes negative lowering the base voltage on Q254 This 3 22 reduces the current into pin 13A which causes the dc common mode voltage at pin 3 and 13 to decrease The voltage at pin 13A depends on the switch mode When the VERTICAL MODE switch is set to LEFT RIGHT or ALT the voltage on pin 13A is 3 8 volts When the VERTICAL MODE switch is set to ADD the voltage on pin 13A is 4 6 volts Each channel within U232 has an independent pair of control pins for channel selection If the On pin is more positive than the pin that channel is selected Ail of the On pins are held
506. s no effect in this case LO LO ALTERNATE BETWEEN A OUTPUT A HORIZONTAL UNIT EM B HORIZONTAL UNIT CHOP BETWEEN AND B n 1 f output is LO prior to LO it goes and vice versa Actuated by negative going edge Repetition rate one half horizontal chopped blanking rate Repetition rate one half alternate puise rate 2 B MODE Selecting the B horizontal mode provides a Display Command to circuits 3 CHOP MODE the CHOP position of the HORIZONTAL MODE switch the Display B Command switches between the HI and LO levels producing a display that switches between the A and B horizontal units at a 0 2 megahertz rate The repetition rate of the Display B Command in this mode is determined by the Horizontal Chopped Blanking pulse see Chop Counter 3 12 description later in this section Each time the Horizontal Chopped Blanking pulse at pin 1 U4358 drops LO the output at pin 6 switches to the opposite state 4 ALT MODE For ALT horizontal operation the Display B Command switches to the opposite state each time the negative portion of the Alternate pulse is received from the Horizontal Logic stage Hepetition rate of the Display B Command in this mode is one half the repetition rate of the Alternate pulse applied to pin 8 VERTICAL BINARY The Vertical Binary stage produces the Vertical Alternate Command at pin 6 to determine which vertical unit will be display
507. s to the rear heatsink Then remove the 2 screws securing the Low Voltage regulator chassis to the main power supply chassis located in front of the A22 Low Voltage Regulator board Now remove the board and attached chassis Remove the mounting hardware securing the plastic cased power transistors to the rear heatsink see Fig 4 13 Note the position of the lockwashers so they can be correctly replaced Remove the 5 securing screws and lift the board with attached power transistors from the chassis Maintenance 7904A To replace the A22 Low Voltage Regulator board first apply a thin coat of silicone grease to the back mounting surface of each power transistor WARNING Handle silicone grease with care Avoid getting silicone grease in your eyes Wash hands thoroughly after use Piace the A22 Low Voltage Regulator board on the chassis Repiace but do not tighten the securing screws Check that the power transistors are aligned with their mounting screws and that the insulating washers are in place between the transistor cases and the rear heatsink Secure the transistors with the mounting hardware Do not over tighten the nuts recommended torque is four to six inch pounds Tighten the screws holding the A22 Low Voltage Regulator board to the chassis PLASTIC CASED POWER TRANSISTORS A25 LOW VOLTAGE REGULATOR BOARD REPLACE MICA INSULATORS PLACE POWER TRANSISTOR ON MOUNTI
508. screws Connect the precision dc voltmeter DVM set to measure at least 130 volts between TP127 located on the A20 High Voltage Board and chassis ground WARNING Extreme caution must be used when making the following adjustments due to the dangerous potent als present Press the POWER button to on EXAMINE the voltmeter for a reading of 96 to 104 volts ADJUST HV Adi R115 located on the A20 High Voltage Board for 100 volts on the voltmeter Press POWER button to OFF Remove the DVM test leads and re install the A20 High Voltage Board shield Press POWER button to on Checks and Adjustment 7904A Part li Adjustment and Performance Check B3 ADJUST Z AXIS DC LEVELS A21R135 A21R125 NOTE If the preceding step was not performed first perform step B1 then proceed B3 SETUP CONDITIONS 7904A Controis HORIZONTAL MODE Test Oscilloscope 10X probe Test Equipment Controls Test Oscilloscope Sweep Rate 20 us div Vertical Deflection 0 5 V div 5 Voit at probe tip DC Input Coupling A Time Base Unit Sweep Rate 50 us div Triggering Auto AC internal Amplifier Position Off screen 4593 504 Set the test oscilloscope input coupling to ground Move the ground reference trace to the bottom graticule of the test oscilloscope display Return the test oscilloscope input coupling to dc Connect the test oscilloscope 10X probe to TP183 located on the A21
509. sed in conjunction with the following data to aid in locating a defective component An understanding of the circuit operation is helpful in locating troubles See Section 3 Theory of Operation for this information TROUBLESHOOTING AIDS DIAGRAMS Complete schematic diagrams are given on the pullout pages in Section 8 Diagrams and Circuit Board Hlustrations The component number and electrical value of each component in this instrument are shown on these diagrams See the first page of the Diagrams and Circuit Board Illustrations section for definitions of the reference designators and symbols used to identify components in this instrument Important voltages and numbered waveform test points are also shown on the diagrams The waveforms and the numbered test points where they were obtained are located adjacent to each diagram The portions of circuits mounted on circuit boards are enclosed with heavy solid black lines CIRCUIT BOARD ILLUSTRATIONS To aid in locating circu t boards a circuit board location illustration appears on the back of the pullout page facing each schematic diagram in addition an illustration of the circuit board s is included here with the physical location of the components and waveform test points that appear on the schematic diagram identified Each circuit board illustration and schematic diagram is arranged in a grid locator with an index to facilitate rapid location of components contained on the
510. shield from the circuit board TP34 is labeled TANK on the A23 Power Supply Inverter circuit board Set the variable autotransformer for 20 volts and check for a filtered line waveform which is centered at 0 volt see Fig 4 8 If the waveform is not centered check Q46 CR32 CR40 CR49 CR45 for shorts or leakage Step Check LV Rectifier Circuit 1 Disconnect the 7904A power cord plug from the power source and discharge the line storage capacitors in the power supply unit following the procedure given under Access to Components in the Power Supply Unit inspect the A12 Control Rectifier circuit board and connecting cables for shorts and damaged components Remove dua diode CR151 from the A12 Control Rectifier board and check with a curve tracer Re install tested or replaced parts making certain that the case is not shorted to the heat sink Maintenance 7904A 1988 104 Figure 4 7 Current waveform at A23T30 for normal inverter operation at line voltage of 115 volts 1988 105 Figure 4 8 Waveform at IP34 on the A23 Power Supply Inverter circuit board with the line voltage at about 20 volts 3 Lift one leg each of CR140 CR141 CR142 and CR143 on the A12 Controi Rectifier board and check with a curve tracer Reconnect tested or replaced parts Lift one leg each of CR130 CR131 CR132 CR133 CH150 and CR153 on the 12 Rectifier board and check with a curve tracer Reconne
511. splay is compressed vertically within the crt graticule area The signal at the output of 0515 pins 17 and 19 is connected via a flexibie coplanar transmission line to the crt vertical deflection plate neck pins A distributed deflection plate system is used in the crt for maximum bandwidth The signal travels along the deflectors at a velocity essentially the same as the velocity of the electron beam passing through the vertical deflector This synchronism of the deflection signal and the electron beam reduces the joss in high frequency sensitivity due to electron transit time through the 3 54 deflection plate structure After propagating along the defiection plates the signal exits the crt into a termination network consisting of R83 R83 is adjustable to match the crt impedance deflection structure to the crt termination OUTPUT PROTECTION Transistors Q722 and 0720 comprise a protection circuit for U515 in case the 15 volt supply is shorted to ground if this occurs 0722 turns on causing the base of Q720 to drop below 35 voits Thus the emitter voltage of Q720 is kept at a safe level U515 AUXILIARY AMPLIFIER The Auxiliary Amplifier is used to inject low frequency S2MHz signals associated with crt scale factor readout and alternate sweep switching into the vertical deflection system Normally the X Y Inhibit signal entering at J26 is LO 0 6 V 0541 and 0630 are off and Q631 is on The Aux Y Axis signal
512. t R101 on the A28 Horizontal Amplifier Board so that all characters are displayed within the limits of the graticule area Set the 7904A POWER switch to OFF and replace Q2225 in its socket 5 57 Checks and Adiustment 7904A Part li Adjustment and Performance Check E6 CHECK ADJUST HIGH FREQUENCY 9 ADJUST high frequency timing adjustments C810 TIMING 28 810 28 850 A28C310 E 28 340 A28R312 A28R340 A28C922 for alignment of the second and tenth sine wave and C850 on the A28 Horizontal Amplifier Board NOTE If the preceding step was not performed first perform step E1 then proceed SETUP CONDITIONS 7904A Controls POWER Switch HORIZONTAL MODE Time Mark Generator gt 5 x a 4 Marker Output Coaxial Cable Test Equipment Controls Time Base Triggering Auto AC internal Sweep Rate 1 ms div Time Mark Generator 1 ms markers J 4593 532 2 Set the amplifier deflection factor for approximately two divisions of display set the time base Triggering Level as necessary for a stable display EXAMINE crt display for one time marker per division over the center eight divisions ADJUST time base unit front pane Swp Cal adjustment for one time marker per division over the center eight divisions CHECK refer to the Performance Check procedures in the time base unit instruction service manual to check high frequency timing and accuracy to
513. t operation VISUAL INSPECTION The 7904A should be inspected occasionally for such defects as broken connections improperly seated semiconductors damaged or improperly installed circuit boards and heat damaged parts The corrective procedure for most visible defects is obvious however particular care must be taken if heat damaged parts are found Overheating usuaily indicates other trouble in the instrument therefore correcting the cause of overheating is important to prevent recurrence of the damage SEMICONDUCTOR CHECKS Periodic checks of semiconductors are not recommended The best check of semiconductor performance is actual operation in the instrument More details on semiconductors are given under Troubleshooting later in this section PERIODIC ELECTRICAL ADJUSTMENT To ensure accurate measurements check the electrical adjustment of this instrument after each 2000 hours of operation or every 12 months if used infrequently In addition replacement of components may necessitate adjustment of the affected circuits Complete adjustment instructions are given in Section 5 Checks and Adjustments These procedures can be helpful in localizing certain troubles in the instrument and in some cases may correct them Maintenance 7904A TROUBLESHOOTING The following information is provided to facilitate troubleshooting of the 7904A Oscilloscope mainframe Information contained in other sections of this manual should be u
514. t signal at pin 8 of U4485 which sets the intensity of the crt display except for the readout display which is controlled by the Readout System The output current at pin 8 is determined by the setting of the or B INTENSITY controls and the Auxiliary Z Axis input The Auxiliary Z Axis input is produced by either the External Z Axis input or by an input from any of the plug in units see Main Interface diagram 3 The input current from the A and B INTENSITY controls is switched for proper timing with the output to the horizontal display The Vertical Chopped Blanking Horizontal Chopped Blanking and Readout Blanking signals are applied to this stage to block the output current and biank the crt display for vertical chopping horizontal chopping or during a readout display The inputs to the Z Axis Logic stage 04485 pin 1 2 9 and 16 are current driven and are variable from zero to four milliamperes The Vertical Chopped Blanking Horizontal Chopped Blanking and Z Axis Inhibit signals enabie or disable this stage to control all output current Quiescently the level at pins 6 and 7 is HI so that the intensity current from pins 1 2 9 and 16 can pass to the output However both pins 6 and 7 go LO during Vertical Chopped Blanking during Horizontal Chopped Blanking or during readout d splay This blocks the output current and blanks the crt The Vertical Chopped Blanking signal is connected to pins 6 and 7 of U4485 directly f
515. t Geometry and Adjust Trace Alignment Focus A20R155 A20R55 A2R2025 A20R143 A29R122 8 Adjust Crt Grid Bias A20R65 9 Adjust Auto Focus Amplifier Gain 2 6 id CE 10 Examine External Z Axis Operation Co Cn 9 om op omo don C CALIBRATOR AND OUTPUT SIGNALS 1 Calibrator and Output Signals Preliminary Setup 2 Check Adjust Calibrator Output Voltage A5R385 3 Check Adjust Calibrator 1 kHz Repetition Rate 5 375 4 Check Calibrator Rise Time Fall Time and Duty 5 Check A and B Sawtooth Output Signals Pe EE Check A and B Gate Output Signals Check Graticule Illumination Operation 4 n 5 36 D TRIGGER SYSTEM 1 Trigger System Preliminary Setup 2 Adjust A Trigger Selector Centering A14R255 A14R270 A14R274 148279 3 Adjust B Trigger Selector Centering and Gain A14R455 A14R474 A14R479 4 Check Adjust Vertical Signal Out DC Centering A14R485 A14R480 A14R490 5 Check Trigger Selector Operation E HORIZONTAL SYSTEM 1 Horizontal System Preliminary Setup 2 Adjust Horizontal Amplifier Limit Centering A28R630 3 Adjust Horizontal Amplifier Centering T uc cohors us dx aues xal xe d 4 Check Adjust Horizontal Gain and Low Frequency Linearity A28
516. t board and the pin This spring tension can be destroyed by using the pin sockets as a connecting point for spring loaded probe tips alligator clips etc 4 27 Maintenance 7904A REPLACEMENT PIN SPARE FERRULE PROPER PLACEMENT OF FERRULES IN CIRCUIT BOARD 1967 5 Figure 4 16 Exploded view of circuit board pin and ferrule Muiti Pin Connectors The pin connectors used to connect the wires to the interconnecting pins are clamped to the ends of the associated leads To remove or replace damaged multi pin connectors remove the old pin connector from the end of the lead and clamp the replacement connector to the lead NOTE Some multi pin connectors are equipped with a special locking mechanism These connectors cannot be removed by pulling on the wire s To remove the connectors from the pin s grasp the plastic holder and pull To remove an individual wire from the holder insert a scribe in the hole on the side of the holder and slide the extended portion under the holder This will allow the wire to be removed from the holder Some of the pin connectors are grouped together and mounted in a plastic hoider the overall is that these connectors are removed and installed as a multi pin connector see Troubleshooting Aids if the 4 28 individual end lead pin connectors are removed from the plastic holder note the order of the individual wires for correct replacement into the hoider PUS
517. t can be displayed on the crt The first three time siots produce a space whether data is encoded or not see previous paragraph When decimai point data is encoded the crt is unblanked so a readout display is presented Since row 7 does not activate any of the five Character Generators the crt beam is deflected verticaily by tne application of row 7 data to the Y input of the Format Generator through R2278 R2280 This places the decimal point between the characters along the bottom line of the readout word After the decimal point is produced in the addressed location the crt beam returns to the location indicated by the Character Position Counter to produce the remainder of the display FIRST POSSIBLE CHARACTER DIS PLAYED ON CRT AT THIS LOCA TION FIRST NUMBER OF MEASUREMENT NORMALLY DISPLAYED AT THIS LOCATION 3 0 0 0 0 0 DECIMAL POINT LOCATION NO 6 COLUMN 6 T POINT ALWAYS LOCATION NO 4 SKIPPED COLUMN 4 EVEN IF NO DATA ENCODED DECIMAL POINT LOCATION NO 3 DECIMAL POINT LOCATION NO 5 DECIMAL POINT LOCATION NO 7 C1195 37 Figure 3 18 Readout word relating 10 possible character locations to the decimal point instructions that can be encoded and the resultant crt display 3 36 FORMAT GENERATOR The X and Y deflection signals produced by the Character Generator stage are connected to pins 2 and 7 respectively of the Format Generator The Channel Address Code from the Channel Cou
518. t from the circuit board 3 Disconnect the pin connectors and remove the 5 screws holding the board to the chassis NOTE When removing wires from a circuit board always tag the wire and the corresponding connection point on the circuit board 4 Slide the board toward the rear of the instrument until the front panel pushbuttons clear the chassis 5 Lift the board from the instrument 6 Replace the board by reversing the order of removal Match the index arrow on the pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown on the circuit board illustration in Section 8 Diagrams and Circuit Board IHustrations A6 Main Interface Circult Board Remove and replace the A6 Main Interface circuit board as follows 1 Remove the plug in units and the power supply unit see Power Supply Unit Removal 2 Disconnect connectors from the A6 Main interface board Note the location of the connectors so they can be correctly replaced 3 Remove the screws from inside each plug in compartment which hold the plug in interface connectors to the chassis see Fig 4 12 4 Slide the Main Interface board assembly to the rear of the instrument and remove it 5 Heplace the A6 Main Interface circuit board in the reverse order of removal Match the index arrow on the pin connectors to the corresponding arrow on the board Correct location of the pin connectors is shown in the circuit
519. t replacement and internal adjustments must be made by qualified service personnel only OPTION 2 Option 2 provides phase correction when operating in the X Y Mode A delay compensation network is added to equalizes the signal delay between the vertical and horizontal deflection systems When the compensation network is installed and activated the phase shift between the vertical and horizontal channeis is adjustable to less than 2 from dc to 1 megahertz Option 2 can be added at any time Refer to your Tektronix Products catalog or contact your local Tektronix Field Office OPTION 3 Option 3 enables the 7904A to meet the EMC electromagnetic compatibility specifications given in Section 1 General information of this manual Option 3 can be added at any time Refer to your Tektronix Products catalog or contact your local Tektronix Field Office OPTION 4 Option 4 provides a 4 cm x 5 cm crt display with P31 phosphor OPTION 13 Option 13 provides a 4 cm x 5 cm crt display with P11 phosphor OPTION 78 Option 78 provides a 8 cm x 10 cm crt display with P11 phosphor OPTION A1 The standard power cord is replaced with Universal European 240 volt type power cord OPTION A2 The standard power cord is replaced with the United Kingdom 240 volt type power cord OPTION A3 The standard power cord is replaced with the Australian 240 volt type power cord OPTION A4 The standard power cord is replaced with the North A
520. t the front panel FOCUS and INTENSITY controls for a well defined display CHECK that the vertical and horizontal traces which cross at graticule center are aligned with the graticule vertical and horizontal center lines within 0 1 division ADJUST the Y Axis Align adjustment R122 on the A29 Horizontal Interface Board and the front panel TRACE ROTATION adjustment R2035 on the A2 Display Control Board to align the vertical and horizontal traces with the graticule horizontal and vertical center lines The Y Axis Align adjustment R122 is accessible using a thin bladed screwdriver from the side of the instrument just forward of and below the fan CHECK the horizontal trace at the top and bottom of the graticule for 0 1 division or less of bowing or tilt ADJUST Geom adjustment R143 on the A20 High Voitage Board for minimum bowing of the traces at the top and bottom of the graticule Press the POWER button to OFF and re install the High Voltage Board shield Press the POWER button to on Checks and Adjustment 7904A Part li Adjustment and Performance Check 88 ADJUST CRT GRID BIAS A20R65 NOTE if the preceding step was not performed first perform step B1 then proceed B8 SETUP CONDITIONS 7904A Controls VERTICAL MODE HORIZONTAL MODE A and B INTENSITY GRAT ILLUM Fully counterclockwise Fully counterclockwise Precision DC Voltmeter DVM _ 8 ae 8 Si
521. tage occurs as follows If the output level of this supply decreases becomes less positive due to an increase in load or a decrease in input voltage as a result of line voltage change or ripple the voltage across divider R16 R15 and R14 decreases also This results in a less positive level at pin 2 of U15 than that established by zener diode VR12 at pin 3 of U15 This decreases the current through CR15 and VR17 causing an increase in current through the base emitter junction of 028 This results in increased conduction of Q28 the 50 volt series regulator The load current increases therefore the voitage across the load also increases becomes more positive sufficiently to balance the input into differential amplifier U15 The 50 V ADJ R15 sets the output level of this supply Current limiting is provided for the 50 volt supply if excessive current is demanded from the supply Since the load is connected to this supply through 828 ali current from the 50 volt supply must flow through this resistor Under norma operation there is insufficient voltage drop across R28 to turn Q22 off However when excessive current is demanded from the 50 volt series regulator 028 due to a short circuit or similar malfunction at the output of this supply the voltage drop across R28 increases and begins to turn off 022 The reduced collector current of Q22 results in a reduction of current through Q28 This current limiting protects Q28 from
522. tage operation when display skip condition occurs REV NOV 1985 or B INTENSITY controls The Readout Intensity line also provides a means of turning the Readout System off when a readout display is not desired When the Readout Intensity line is left open the current from pin 11 of U2126 is interrupted and at the same time a positive voltage is applied to pin 4 through CR2124 The positive voltage switches the stage to the same conditions as were present under the Display Skip condition Therefore the crt display is not interrupted to present characters However time siot pulses continue to be generated TIME SLOT COUNTER Time Slot Counter U2159 is a sequential switch which directs the trapezoidal waveform input at pin 8 to one of its 10 output lines These time slot pulses are used to interrogate the plug in units to obtain data for the Readout System The trigger pulse at pin 15 switches the Time Slot Counter to the next output line the output signal is sequenced consecutively from time slot 1 through time slot 10 Figure 3 14 shows the time relationship of the time slot pulses Notice that only one line carries a time siot pulse at any given time When time siot 10 is completed a negative going end of word pulse is produced at pin 2 The end of word pulse provides a drive pulse for the Word Trigger stage and also provides an enabling level to the Display Skip Generator during time slot 1 only Pin 16 is a reset input for the T
523. tch LEFT ALT Display alternates between Left and Right Vertical units at rate determined by Horizontal plug in unit s ADD Display is algebraic sum of Left and Right Vertical units CHOP Display chops between Left and Right Vertical units asynchronousiy to Horizontal plug in unit s RIGHT Right Vertical unit displayed SLAVED ALT Slaved Alt operation ocurrs if 1 VERT MODE switch is set to ALT 2 HORIZ MODE Switch is set to ALT or CHOP 3 Time base unit is installed in each Horizontal compart ment and 4 Time base unit installed in HORIZ compart ment operates in slaved mode When in slaved alt operation the display alternates between 1 the trace pro duced by the LEFT VERT unit displayed at the sweep rate of B time base unit and 2 the trace produced by customer verification Satisfactory operation is substantiated at the factory F10 Check Vertical Display Modes 4 5 3 Checks and Adjustment 7904A Characteristics Vertical Display Modes cont SLAVED ALT cont VERTICAL TRACE SEPARATION B A and B TRIGGER SOURCE Met enean m meneame earum nmn d VERT MODE LEFT Performance Requirements TABLE 5 2 CONT Performance Check Summary Part 11 Part i Performance Check Adjustment and Procedure Title Performance Check Procedure Title VERTICAL SYSTEM CONT t
524. tch to CHOP 5 54 D5 CHECK TRIGGER SELECTOR OPERATION i crt for a stable display of the 1 kHz waveform only Set the A TRIGGER SOURCE switch to LEFT VERT CHECK sequentially select all positions of the VERTICAL MODE switch and check for a stable display of only the 1 kHz waveform Set the A TRIGGER SOURCE switch to RIGHT VERT CHECK sequentially select all positions of the VERTICAL MODE switch and check for a stable display of the 10 kHz waveform Set the VERTICAL MODE switch to ALT the HORIZONTAL MODE switch to B and the B INTENSITY contro for a visible display CHECK the crt display for 1 kHz and 10 kHz triggered waveforms Set the VERTICAL MODE switch to ADD for a stable display Set the VERTICAL MODE switch to CHOP CHECK crt for a stable display of only the 1 kHz waveform Set the B TRIGGER SOURCE switch to LEFT VERT CHECK sequentially select ail positions of the VERTICAL MODE switch and check for a stable display of oniy the 1 kHz waveform Set the B TRIGGER SOURCE switch to RIGHT VERT CHECK sequentially select all positions the VERTICAL MODE switch and check for a stable display of only the 10 kHz waveform Set the VERTICAL MODE switch to ALT the HORIZONTAL MODE switch to ALT and the A and B TRIGGER SOURCE switches to VERT MODE CHECK that the B HORIZ time base is triggered on the 1 kHz waveform and the A HORIZ time base
525. tches The preceding information gave a typical exampie of encoding data from an amplifier plug in unit Specific encoding data and circuitry is shown in the individual plug in unit manuals COLUMN AND ROW DATA SWITCHES The encoding data from the plug in units is connected to the Column and Row Data Switch stages A column data line and a row data line convey analog data from each of the 8 data sources 2 channels from each of the 4 plug in compartments The Column Data Switch 02190 and the Row Data Switch U2180 receive the Channel Address Code from the Channel Counter refer to Diagram 6 at the rear of this manual This binary code directs the Column Data Switch and the Row Data Switch to the channei which should be the source of the encoding data Table 3 12 gives the eight combinations of the Channel Address Code and the resultant channel selected with each combination These stages have nine inputs and provide a time multiplexed output at pin 7 which includes the information from all of the input channels Eight of the nine inputs to each stage originate in the plug in units the ninth input comes from a special data encoding network composed of resistors R2191 through R2199 and R2201 through R2209 See Zeros Logic and Memory description for further information on ninth channel in addition to the encoding data inputs from the plug in units inputs are provided to the Column Data Switch from the VERTICAL MODE and HORIZONTAL MODE
526. tegrated circuits U2270 U2272 U2274 U2276 U2278 which generate the X horizontal and Y vertical outputs at pins 16 and 1 respectively to produce the character display on the crt Each integrated circuit can produce 10 individual characters 92270 designated Numerals produce the numerals 0 through 9 shown in row 1 of the Character Selection Matrix Fig 3 9 Integrated circuit U2272 can produce the symbols shown in row 2 of the Character Selection Matrix and U2274 produces the prefixes and some letters used as prefixes shown in row 4 Integrated circuits U2276 and 02278 produce the remaining letters shown in rows 5 and 6 of the Character Selection Matrix Theory of Operation 7904A All of the Character Generator stages receive the Column Digital Data from the Column Decoder U2244 in parallel However only one of the Character Generators receives row data at a particular time and only the stage receiving this row data is activated For example if column 2 is encoded the five character Generators are enabled so that either a 1 V or an can be produced If row 4 has been encoded at the same time only the Prefix Character Generator U2274 will produce INPUT PIN OF U2232 ACTIVATED COMMAND TIME SLOTS IDENTIFY 12 ADD ONE ZERO 13 ADD TWO ZEROS 10 DECREASE PREFIX DECREASE PREFIX AND ADD ONE ZERO C1195 36
527. terminal A37 of the plug in interface Resistor R111 connected between time siot 1 and the col umn analog data output encodes two units of current dur 3 45 Theory of Operation 7904A ing time slot 1 Referring to the Character Selection Matrix Figure 3 20 two units of column current along with the two units of row current encoded by resistor R10 row 3 indi cates that two zeros should be added to the display Resis tor R120 adds one unit of column current during time siot 2 and aiong with the one unit of current from the row output the Readout System is instructed to add an invert arrow to the display Resistor R130 is not connected to the time slot 3 line since the deflection factor is calibrated Therefore there is no display on the CRT during TS 3 See Display Skip Generator for further information During time slot 4 two units of column current are encoded by R140 There is no row current encoded during this time slot resulting in the numeral 1 being displayed on the CRT Neither row nor column analog data is encoded during time slots 5 6 and 7 as defined by the Standard Readout For mat During time slot 8 two units of column current and three units of row current are encoded by resistors R181 and R80 respectively This addresses the prefix in the Character Selection Matrix The final data output s pro vided from time siot 9 by R190 connected to the column output and R90 to the row output These resist
528. tes when selected by the HORIZONTAL MODE switch INTENSITY Indicator illuminates when selected by the HORIZONTAL MODE switch INTENSITY Control to determine brightness of trace produced by the plug in unit installed in the A HORIZ compartment B INTENSITY Control to determine brightness of trace produced by the plug in unit installed in the B HORIZ compartment CONTRAST Screwdriver adjustment varies brightness of intensified portion of display READOUT INTENSIFY Contro to determine brightness of readout display Disables Readout System in counterclockwise detent position Activates PULSED in clockwise detent position READOUT PRESET Screwdriver adjustment PULSED operation only sets PULSED readout intensity READOUT GATE OR EXT Switch to select either GATE or EXT actuation of the PULSED readout mode A OR SAWTOOTH Switch to select A or time base unit as source for SAWTOOTH OUTPUT signal SAWTOOTH Connector to output signal derived from the A or B time base unit READOUT MAN Switch when pressed actuates one frame of readout display OR B GATE Switch to select either A or B time base unit as source of GATE output GATE Connector to output positive going gate signal from the time base unit in the A or B horizontal compartment 9 eG gt 9 9 Operating instructions 7904A GRAT Hiumination or fuctions ILLUM Control varies
529. th a 42 inch coaxial cable Set the left amplifier unit deflection factor to display a signal amplitude of 2 divisions centered on the screen Set the A horizontal time base unit triggering for a stable display DISPLAY FOCUS 10 Rotate the FOCUS and ASTIG controls and observe the square wave display Notice that the thickness of the trace varies Set the FOCUS and ASTIG controls for a well defined trace TRACE ALIGNMENT 11 Disconnect the input signal Using the left amplifier unit Position control align the trace with the center horizontal graticule line If necessary use the TRACE ROTATION control to align the trace with the center graticule line GRATICULE ILLUMINATION 12 Rotate the GRAT ILLUM contro throughout its range and notice that the graticule lines are illuminated as the control is turned clockwise Notice that in the fully clockwise detent the graticule illumination is in the PULSED MODE Press the MAN button and notice the graticule is illuminated each time the button is pressed Refer to Graticule in the Detailed Operating information for more information Operating instructions 7904A CONTROL ILLUMINATION 13 14 Set the rear panel CONTROL ILLUMINATION switch to HIGH Notice that the A INTENSITY indicator and the lighted pushbutton switches on the 7904A and plug in units are all illuminated to a high intensity level Sequentially press all of the HORIZONTAL MODE switc
530. the 7020 features include a complete alphanumeric crt display of cursor waveform information and measurement values time base and amplitude settings trigger position displayed waveform number prompts and error messages and a master menu that aliows quick and easy selection of seidom used features Complete control of the Waveform Digitizer s functions may be controlled via the IEEE 488 Interface Commands waveforms and alphanumeric test messages may be sent or received via the front panel port Readout Access Plug in Unit The 7M18 READOUT plug in unit provides front panel keyboard operation for convenient access to the crt readout characters This allows information such as dates and identifying nomenciature to be displayed on the crt with the normal crt display This capability is particularly useful when making photographs Transistor Curve Tracer Plug in Units The 7000 series transistor curve tracer plug in unit 7CT1N checks signal transistors and diodes by producing a display showing the basic characteristic curves for the device being tested Stepped sweep signals from an internal power supply are applied to the device under test The resulting output signals are in Operating instructions 7904A turn applied to the horizontal and vertical deflection systems of the oscilloscope to plot a family of characteristic curves This plot can be used to check for damaged transistors and diodes or to select for spe
531. the outputs of the Row and Column Decimal to BCD Converters when a readout character is to be dis played The Lower Order Address Generator is enabled and also provides a 4 bit binary code These twelve bits are combined to form the EPROM address containing the 8 bit binary word which will locate the instrument beam at the character s starting grid location The 8 bit word can be broken down into four parts The lower three bits are the horizontal grid coordinate bits 4 through 6 are the vertical coordinate bit 7 turns the Z Read out on and off and bit 8 indicates whether or not the char acter is complete The character grid Fig 3 22 can be thought of as having vertical and horizontal coordinates numbered 0 through 7 with location 0 0 in the lower left corner The 8 bit binary word from the Character Generator is converted to octal to easier recognize the vertical and horizontal coordinates A binary 00001010 becomes octal 012 This number would cause the instrument CRT beam to point at grid co ordinates vertical 1 and horizontal 2 The fact that the first octal digit is 0 indicates two things First it shows that bit 7 of the binary word is LO which turns off Q2132 and the Z Readout signal to the instrument It also shows that bit 8 is LO so the character is not complete When bit 7 is HI it advances the Horizontal Character Position Counter for the next character within the readout word The 4 bit outputs from the R
532. their function Theory of Operation 7904A TABLE 3 1 Basic Logic Symbols Truth Tables Basic Alternate CT ey Description of Basic and INPUT INPUT OUTPUT Alternate Symbols A B x AND A device with two or more inputs amp one output device with two or more inputs amp one output A device with two or more inputs amp one output NOR device with two or more inputs amp one output A device with one input amp one output The output is always the opposite state of the input Exclusive eT fm i A device with two inputs amp one output Negation smal circle at the input or output of a symbol indicates that indicator the LO state is significant Absence of the circle indicates that Symbol the state is significant The first part of this table includes the alternate way to draw the same gate The type of symbol used depends on how the gate is used in the circuit 1 The Basic symbols require active Hl input and the Alternate symbols require an active LO input 3 4 Theory of Operation 7904A TABLE 3 1 CONT Basic Logic Symbols Positive Negative Edge triggered Edge triggered Dynamic indicator Indicates that this input responds to the indicated Symbol transition of the applied signal RS Flip Flop Input Output When the 5 input is HI the output will be When the R input is the Q output will be LO The outputs are complementary except when 5
533. they do not catch on other parts of the instrument The power supply unit remains electrically connected to the rest of the instrument in this position allowing for troubleshooting If it is necessary to operate this instrument with the power 4 15 Maintenance 7904A DISPLAY UNIT DISPLAY UNIT KICKSTAND ACQUISITION UNIT REMOVE REMOVE COUPLING Figure 4 10 Use of Display Unit kickstand supply unit removed for a period of time we recommend that the power supply unit be secured to the instrument with spacers between the rear frame and the power supply unit Reverse the above procedure when placing the power supply unit into the mainframe of the instrument be careful not to pinch the interconnecting cables when replacing the unit Be sure that all the securing screws are tight enough to hold the power supply unit properly in place Access to Components in the Power Supply Unit To reach the components located inside the power supply unit for maintenance or repair use the following procedure 4 16 Disconnect the instrument from the power source and allow the line storage capacitors to discharge before removing the power supply unit cover The line storage capacitors remain charged with high voltage dc for several minutes after the line power 15 disconnected unless they are manually discharged warning indicator neon bulb located on the A23 Power Supply inverter board flashes when this stored v
534. through CR2125 from the Display Skip Generator stage This signal causes the Timer to shorten its period of operation to about 210 microseconds The waveforms in Figure 3 13 show the operation of the Timer stage when the Display Skip condition occurs for all positions in a word Notice that there is no output at pins 12 13 14 and 16 under this condition This means that the crt display is not interrupted to display characters Also notice that the triangle waveform at pin 6 does not go as far negative and that the negative portion of the trapezoidal waveform at pin 10 is shorter Complete details on operation of the Display Skip Generator are given later The Timer operation is also controlled by the Single Shot Lockout level at pin 2 If this level is LO the Timer operates as just described However if the Single Shot Lockout stage sets a level at this pin the Timer stage is locked out and can not produce any output signals see Single Shot Lockout description for further information A negative voltage on the readout Intensity line sets the intensity of the readout display independently of the A 3 28 1195 31 4593 61 TRIGGER PIN 5 CHARACTER SCAN PIN 16 SN 031766 amp BELOW Z AXIS LOGIC OFF COMMAND 14 VERTICAL AND HORIZONTAL poor OFF COMMAND PIN 13 READOUT INTENSITY PIN 12 TP2251 SN 8031766 amp BELOW OR 02127 PIN 5 SN 8031767 amp UP Figure 3 13 Timer s
535. time base unit can be installed in any compartment 3 The capabilities of the plug in units used with this instrument e g a dual trace amplifier unit can be used in either of the two single channel modes in a duai trace mode or in an algebraically added mode A dual time base unit may be used for an independent sweep or for a delayed sweep in the B Horizontal compartment Therefore it is difficult to list all of the display combinations which can occur during use of the 7904A and available plug in units Table 2 1 lists the combination of VERTICAL MODE and HORIZONTAL MODE switch positions available and the type of display obtained with each combination Vertical Modes When the LEFT or RIGHT button of the VERTICAL MODE switch is pressed only the signal from the plug in unit in the selected compartment is displayed Alternate Mode The ALT position of the VERTICAL MODE switch produces a display which alternates between the LEFT VERT and RIGHT VERT compartments with each sweep of the crt Although the ALT mode can be used at all sweep rates the CHOP Operating Instructions 7904A mode provides a more satisfactory display at sweep rates slower than 20 milliseconds division At these slower sweep rates alternate mode switching becomes perceptible Aiternate Mode displays have three types of triggering available When the A and B TRIGGER SOURCE switches are set to the VERT MODE positions each sweep is triggered by the si
536. ting Instructions 7904A established The easiest way to obtain the correct setting of the FOCUS control is to set the READOUT INTENSITY contro so that the readout portion of the display is clearly visible Adjust the FOCUS control for the best definition of the readout display ASTIGMATISM FOCUS ADJUSTMENTS If a well defined display cannot be obtained with the FOCUS control adjust the ASTIG adjustment as follows NOTE To check for proper setting of the ASTIG adjustment slowly turn the FOCUS control through the optimum setting If the ASTIG adjustment is correctly set the vertical and horizontal portions of the display will focus at the same position of the FOCUS control This setting of the ASTIG adjustment should be correct for any display 1 Install amplifier unit in the LEFT VERT compartment and a time base unit in the A HORIZ compartment 2 Set the VERTICAL MODE switch to LEFT and the HORIZONTAL MODE switch to 3 Connect the output of a sine wave generator to the input of the amplifier unit Set the sine wave generator repetition rate to 1 kilohertz and the vertical amplifier deflection factor for a 2 division display 4 Set the time base unit sweep rate for 0 2 millisecond division and the triggering for a stable display Set the A INTENSITY control so the display is at a usable intensity level about midrange 5 Turn the FOCUS control fully counterclockwise and set the ASTIG adjustment to midran
537. tion Table 1 2 Power Cord and Plug identification information Table 1 2 Power Cord and Plug identification information Instrument 7904 Information Plug configurations usage and reference standards Plug configurations usage and reference standards Plug configurations usage and reference standards Plug configurations usage and reference standards 6 3 Section 7 7904A REPLACEABLE ELECTRICAL PARTS PARTS ORDERING INFORMATION Replacement parts are available from or through your local Tektronix Inc Field Office or representative Changes to Tektronix instruments are sometimes made to accommodate improved components as they become available and to give you the benefit of the latest circuit improvements developed in our engineering department It is therefore impor tant when ordering parts to include the following information in your order Part number instrument type or number serial number and modification number if applicable if a part you have ordered has been replaced with a new or improved part your local Tektronix Inc Field Office or represen tative will contact you concerning any change in part number Change information if any is located at the rear of this manual LIST OF ASSEMBLIES A list of assemblies can be found at the beginning of the Electrical Parts List The assemblies are listedin numerical order When the complete component number of
538. tion 7904A SPECIFICATION The electrical characteristics listed in Table 1 3 apply when the following conditions are met 1 Adjustment of the instrument must have taken place at an ambient temperature between 20 and 30 C 2 the instrument must be allowed a 20 minute warm up period 3 all specifications are valid at an ambient temperature of 0 to 50 C unless otherwise stated 4 the instrument must be in an environment that meets the limits described in Table 1 4 Any applicable conditions not listed above are expressly stated as part of that characteristic Environmental characteristics are listed in Table 1 4 and Physical characteristics are listed in Table 1 5 Performance Requirements Characteristics Deflection Factor Difference Between Vertical Compartments Low Frequency Linearity Frequency Response With 7A29 Amplifier Unit Step Response Rise time 10 to 90 with 7A29 Amplifier Unit Isolation Between Vertical Compartments 8 Div Signal LEFT RIGHT ALT Modes Delay Line Difference in Signal Delay Between Vertical Compartments Vertical Display Modes LEFT ALT ADD CHOP RIGHT mm taa PTT a a a i e T TTA TABLE 1 3 Electrical Characteristics VERTICAL SYSTEM Compatible with 7000 Series plug in units See Table 1 7 196 or less 0 1 div or less compression or expansion of a center screen 2 div signal positioned anywhere vertically wit
539. tion network is actually two separate delay networks an network and a B The B delay compensation network may or may not be activated depending on the type of plug in in the B HORIZ compartment Operation of the A delay compensation network is achieved by S801 the delay disabie switch located on the X Y Delay Compensation board This switch is normally in the out position which keeps the A delay Compensation network disabled and allows the A HORIZ signal to pass directly to the channel switch input When switched to the IN position S801 connects one side of relays K802 K805 to ground This activates the relays and the A HORIZ signal now passes through the delay compensation network The delay disable switches S801 S811 allow for selection of a display with either minimum phase shift characteristics or optimum step response In the OUT position the delay compensation network is bypasses for optimum step response The Delay Compensation network provides flat time delay with frequency LC network L806 C806 L807 C807 L808 C808 1809 C809 is an ali pass lattice network with a 100 ohm input impedance when terminated in 100 ohms 50 ohms each side Low pass network L802 R802 C803 C804 1805 R805 also has a 100 ohm input impedance when terminated into 100 ADD NOV 1985 Theory of Operation 7904A ohms Only the iow pass network determines the bandwidth of the delay compensation network The total time delay is the sum
540. tment and Performance Check TABLE 5 5 Thermai Compensation Adjustments Signal m Adjustment Standardizer Sweep Rate Rep Rate Comp R130 1 MHz 146 200 238 100 kHz 10 us Comp R335 10 0 1 ms Comp R237 2 1 8132 100 kHz Comp R131 EXAMINE readout dispiay for less than 0 05 divisions of jitter and 0 05 divisions of deviation in the center displayed trace using the time base sweep rates and signal standardizer repetition rates given in Table 5 5 ADJUST Thermal Compensations adjustments on the A18 Vertical Amplifier Board as given in Table 5 5 for minimum readout display jitter and minimum deviation of the displayed center trace list Table 5 5 F6 repeat as INTERACTION 1he adjustments may interact with step F3 F4 F5 a necessary tH in 5 63 Checks and Adjustment 7904A Part 1 Adjustment and Performance Check F6 ADJUST CHANNEL SWITCH COMPENSATION A16C538 A16R530 A16R525 A16R520 A16R515 A16R512 A16C638 A16R630 A16R625 A16R620 A16R615 A16R612 NOTE If the preceding step was not performed first perform step F1 then proceed F6 SETUP CONDITIONS 7904A Controis VERTICAL MODE A TRIGGER SOURCE RIGHT VERT VERT MODE 5 164 P 93 6 ci S 5 Time Base Test Equipment Controis Time Base Sweep Rate 2 us div Triggering Auto AC Internal Signal Standard
541. to trigger the display Set the VERTICAL MODE switch to RIGHT Set the signal standardizer Amplitude and Position controls for a 2 division display in the lower half of the graticule area Set the VERTICAL MODE switch to ALT CHECK the crt display for 1 kHz and 10 kHz triggered waveforms adjust the time base Triggering Level controls as necessary Set the VERTICAL MODE switch to ADD crt display for a triggered waveform Set the VERTICAL MODE switch to CHOP 5 22 waveform only Set the A TRIGGER SOURCE switch to LEFT VERT CHECK sequentially select all positions of the VERTICAL MODE switch and check for a stable display of only the 1 kHz waveform Set the A TRIGGER SOURCE switch to RIGHT VERT CHECK sequentially select positions of the VERTICAL MODE switch and check for a stable display of only the 10 kHz waveform Set the VERTICAL MODE switch to ALT the HORIZONTAL MODE switch to B and the B INTENSITY control for a visible display CHECK the crt display for 1 kHz and 10 kHz triggered waveforms Set the VERTICAL MODE switch to ADD CHECK crt for a stable display Set the VERTICAL MODE switch to CHOP CHECK crt for a stable display of only the 1 kHz waveform Set the B TRIGGER SOURCE switch to LEFT VERT CHECK sequentially select all positions of the VERTICAL MODE switch and check for a stable display of only the 1 kHz waveform Set the B TRIGGER SOURCE switch to RIG
542. tor for input to intensity modulate the displayed trace s LINE VOLTAGE SELECTOR Switch to select either 115 volt or 230 voit nominal source 2 CONTROL ILLUMINATION Three position switch sets illumination level of the A and B INTENSITY indicators A and B TRIGGER SOURCE switches and the lighted pushbutton switches on associated plug in units 4593 23 Figure 2 2 Rear panel controls and connectors Amplifier Unit 2 Required Description Compatible with 7904A Oscilloscope One dual trace unit required to check vertical readout fields Type Used Any of the compatible 7A series units Refer to Table 1 7 in the General information section Time Base Unit 2 Required Description Compatible with 7904A Oscilloscope One Dual Time Base unit or Delaying Time Base unit required to check horizontal readout fields Type Used Any compatible 7B series units Refer to Table 1 8 in the General Information section Sine Wave Generator Description Frequency range 250 kilohertz to 1 megahertz output amplitude tw volts peak to peak into 50 ohms The sine wave generator is used for the Z AXIS INPUT check only Type Used TEKTRONIX FG503 Function Generator requires TM500 power module Coaxial Cables 2 Required Description Length 42 inches connectors bnc Type Used RG 58 U 50 ohm coaxial Tektronix part 012 0057 01 T Connector Description Connectors bnc to bnc
543. tore in a dirt free covered container When several hybrids and Hypcon connectors are to be removed keeps parts together and replace as sets do not interchange parts 2 Hand soldering a Use small diameter solder 0 030inch 0 040inch b Use low wattage soldering irons 15 20 watts Use care with solder amount and placement 3 Remove solder flux and contact contamination with isopropyl alcohol denatured ethyl alcohol or a Freon TF cleaner such as Spray On 2002 4 Flush the hybrid and Hypcon connector mounting area with isopropy alcohol Do not scrub with a cotton tipped applicator as cotton fibers will adhere to edges and surfaces of contact areas and cause open or intermittent connections The elastomer should be examined under light for dust hair etc before it is re installed 1 the etched circuit board surfaces require more cleaning scrub with a soft rubber eraser and biow or vacuum clean while dusting the surface with a small clean brush 5 If the hybrid and elastomer contact holder are contaminated clean by flushing or spraying with alcohol and oven dry at 50 C Do not scrub with a cotton tipped applicator or similar device if the contact holder is excessively contaminated replace it with a new one Two inch pounds of torque should be appiied to the mounting screws to secure the Hypcon to the circuit board Make sure that the elastomer is properly seated in the contact holder before re
544. tput table in Table 3 14 shows the output of the channel switch stage applied to the base of Q67 for each combination of the input conditions The Auto Focus Amplifier is a noninverting operational amplifier consisting of an input comparator Q67 Q68 and an output complementary amplifier Q 77 Q83 Signals out of the data switch are shaped by resistors R63 R62 R64 R65 and diodes CR64 and CR65 Focus Gain adjustment R63 determines the amount of signal to the base of Q67 to set the overall gain of the amplifier stage Signals applied at the base of Q67 are compared with the voltage at the base of Q68 as set by the Focus Output Level adjustment R70 The compared signal is TABLE 3 14 Input Output Relationships for the Auto Focus Channel Switch Bie READOUT INTENSITY A INTENSITY LO B INTENSITY HAS NO EFFECT IN THIS CASE ADD NOV 1985 Theory of 7904 then coupled into the bases of Q77 and Q83 Transistor Q77 normally sets the focus grid voltage However when Q83 conducts due to a change in intensity coupled through the data switch the focus grid voltage changes The output of Q77 Q83 is fed back into the base of Q68 to return the transistor to the normally on condition HIGH VOLTAGE POWER SUPPLY AND CRT The High Voltage Power Supply and CRT circuits provide the potentials necessary for proper operation of the crt cathode ray tube These circuits in coniunction with the Vertical Ho
545. train in the Readout System the puise train consists of 10 negative going pulses Each time slot pulse is assigned a number be tween 1 and 10 For example the first time siot is TS 1 Time Multiplexing Transmission of data from two or more sources over a common path by using different time intervals for different signals Hexidecimal The hexidecimal numbering system uses the numerals 0 through 9 and the letters A through F to represent the sixteen possible cominations of four binary digits Octal The octal numbering system uses the numerals 0 through 7 to represent the eight possible combina tions of three binary digits Binary Coded Decimal The Binary Coded Decimal system uses ten unique combinations of four binary dig its to represent the decimal numbers 0 through 9 DISPLAY FORMAT Up to 8 words of readout information can be displayed on the CRT The position of each word is fixed and is directly related to the plug in unit from which it originated Figure 3 8 3 37 Theory of Operation 7904A 89 t6Sv 1 4 NI W34A1SAS LOHS JTONIS HINN G3A1323H ING T ip e AV IdSIG ONY NYOS LX3N O4 H31Nn0O2 4890 3 NYAAY H3INOOO NOI LISOd H3 LOVHVHOD SNrOM1d HALNNGO NOLLISOd gt HILOVHYH 13538 ALISNALNI OL INV TENA NOLLV2OT1 Ud3iOVuVHO LIXIN
546. trol determines the brightness of the display produced by the plug in unit installed in the A HORIZ compartment The B INTENSITY control determines the brightness of the display produced by the plug in unit installed in the B HORIZ compartment The READOUT intensity control affects the brightness of only the readout portion of the crt display To protect the ort phosphor this instrument contains protection circuitry which limits the display intensity by limiting the crt beam current a safe level if the intensity control s is advanced to a point where the crt beam current exceeds a potentially damaging level for more than about ten milliseconds the circuit action automatically limits the beam current to a safe level The crt beam current is limited to an even iower level when operating in an X Y mode or if either one of the time base units is set to a slow sweep rate even if the time base unit with slow sweep rate is not selected for display by the HORIZONTAL MODE switch This reduces the danger of damaging the crt phosphor with a stationary or slowly moving spot Since beam current limiting does not take effect for about ten milliseconds the full display intensity capability of this instrument is available for most single shot and photographic uses DISPLAY FOCUS This instrument contains an automatic focusing circuit which maintains optimum focus for all intensity settings after a correct setting of the FOCUS control is Opera
547. ts due to short circuits turn on surge currents and other malfunctions When a fault is detected at the Fault Sense input pin 2 or I Sense input pin 13 a current from the Fauit Holdoff Time output pin 1 charges C64 If the detected fault lasts longer than about 10 milliseconds C64 will charge positive enough to initiate a positive output at pin 8 This output turns on Q54 052 which turns off the Inverter The inverter will remain off while C54 discharges through R54 keeping Q54 and Q52 turned on The Inverter restarts in roughly 500 milliseconds when the current through R54 is insufficient to keep Q54 and Q52 turned on When the inverter restarts C54 is recharged through CR59 and R59 This cycle repeats until the fault is corrected with the Inverter on for about 10 milliseconds and off for about 500 milliseconds inverter Current Limiter The inverter current limiter protects the Inverter components from damage due to excessive current turn on or short circuits Operation of this stage is similar to the pre regulator voltage regulation The inverter current limiter takes control of the Inverter hold off time whenever pin 13 starts to go negative Transformer T35 provides a current step down The current is rectified and flows through R84 the current sensing resistor The voltage across R84 is negative and proportional to the Inverter current The Sense input at pin 13 075 is normaily held positive through divider R81
548. ual there is damage or deficiency contact your local Tektronix Field Office or representative POWER SOURCE INFORMATION This instrument can be operated from either a 115 voit or 230 volt nominal supply source 48 to 440 hertz The 1 1 General Information 7904A line fuse remains the same for both 115 volt and 230 volt operation Operating Voltage The LINE VOLTAGE SELECTOR switch located on the rear of the 7904A Oscilloscope mainframe allows selection of 115 volt or 230 volt nominal line voltage operation To select the correct nominal line voltage first change the power cord and plug to match the power source receptacle if necessary Then use a small screwdriver to move the LINE VOLTAGE SELECTOR switch to the desired range To prevent damage to the instrument always check the settings of the LINE VOLTAGE Power Cord information power cord with the appropriate plug configuration is supplied with each instrument For your convenience the color coding of the power cord conductors is given in Table 1 1 Also should you require a power cord plug other than that supplied refer to the Power Cord and Plug Identification Table 1 2 TABLE 1 1 Power Cord Color Conductor Identification Alternate Conductor Color Ungrounded L ne Black I Grounded Neutral Light Blue White SELECTOR switch located on the rear panel irren mundi Green Yellow Green Yellow of the 7904A Oscilloscope mainframe be
549. ucts catalog for applicable oscilloscope system Variable Autotransformer Description Output variable from 0 to 140 volts 10 amperes minimum rating Must have three wire power cord plug and receptacle Purpose Vary input line voltage when troubleshooting in the power supply unit Recommended type General Radio W10MT3W Variac Autotransformer Isolation Transformer Description 1 1 turns ratio 500 volt amperes minimum rating 50 60 cycie Must three wire power cord plug and receptacle with ground connection carried through from input to output Purpose To isolate 7904 from line potential when troubleshooting power supply Recommended type Stancor P6298 for 115 voit line only modified to include three wire power cord plug and receptacle Maintenance 7904A TROUBLESHOOTING TECHNIQUES This troubleshooting procedure is arranged to check the simple trouble possibilities before proceeding with extensive troubleshooting The first few checks ensure proper connection operation and adjustment the trouble is not located by these checks the remaining steps aid in locating the defective component When the defective component is located replace it following the replacement procedures given under Corrective Maintenance 1 CHECK CONTROL SETTINGS incorrect control settings can indicate a trouble that does not exist If there is any question about the correct function or operation of any contro
550. ug to the variable autotransformer turn the 7904A power on Check for stable operation no pulse mode of the power supplies If the power supplies operate properly a crt failure or malfunction in the high voltage circuitry is indicated Step Check ihe Inverter Control Circuit To check the inverter control circuit perform the following procedure 1 Disconnect the 7904 from the power source and discharge the line storage capacitors following the procedure given under Access to Components in the Power Supply Unit see Fig 4 5 Hemove Q54 from the A12 Control Rectifier board Connect the 7904A power cord plug to the variable autotransformer Turn the 7904A on and apply 115 volts from the variable autotransformer If the power supplies stabilize check the inverter control circuit for a malfunction If the 7904A continues in pulse mode proceed to part 4 of this step Repeat part 1 of this step Then remove Q52 from the A12 Control Rectifier board Set the variable autotransformer to 0 volts Connect the 7904A power cord plug to the variable autotransformer Turn the 7904A power on While monitoring the 108 V test point on the A12 Control Rectifier circuit board with a voltmeter slowly increase the output of the variable autotransformer until the voltmeter just reads 108 volts The 108 volt test point is accessible through the A12R93 Pre Reg Adj hole marked R1293 on the panel in the bottom of the Power Supply U
551. ughout its range and check that the trace produced by the B time base unit can be positioned above and below the trace produced by the A time base unit by at least 3 5 divisions Repeat with the HORIZONTAL MODE switch set to ALT 5 30 Checks and Adjustment 7904A Part Performance Check F READOUT SYSTEM Equipment Required Numbers correspond to those listed in Table 5 3 Test Equipment 2 Amplifier Dual Channel F1 READOUT SYSTEM PRELIMINARY SETUP a Perform the Performance Check Power Up Sequence Refer to Section 6 instrument Options and the Change Information at the rear of this manual for any modifications which may affect this procedure Set the 7904 controls as follows POWER switch ccu oes eee etek On VERTICAL RIGHT VERT TRACE SEPARATION B Midrange A TRIGGER SOURCE VERT MODE AJNTENSEITY xus RW Midrange HORIZONTAL A B INTENSITY our gei Ee bee mesa Midrange B TRIGGER SOURCE VERT MODE READOUT INTENSITY OFF in detent GRAT ILLUM Midrange Pushbutton Out Readout selector Free Run SN B031766 amp Below see Test Point and Adiustment Locations G kia Connect pins 1 amp 2 see Test Point and Adjustment Locations Readout Mode Plug P2112 SN B0
552. uire Accumulation of dirt the instrument can cause overheating and component breakdown Dirt on components acts as an insulating blanket and prevents efficient heat dissipation It also provides an electrical conduction path which may result in instrument failure The side panels reduce the amount of dust reaching the interior of the instrument Operation without the panels in place necessitates more frequent cleaning CAUTION Avoid the use of chemical cleaning agents which might damage the plastics used in this instrument Exercise care when cleaning Hypcon connectors see cleaning instructions under Hypcon Connectors this section Use a nonresidue type of cleaner preferably isopropyl alcohol totally denatured ethyl alcohol or a Freon TF cleaner such as Spray On 2002 Before using any other type of cleaner consult your Tektronix Service Center or representative EXTERIOR Loose dust accumulated on the outside of the instrument can be removed with a soft cloth or brush The brush is particularly useful for dislodging dirt on and around the front panel controis Dirt which remains can be removed with a soft cloth dampened a mild detergent and water solution Abrasive cleaners should not be used CRT Clean the plastic light filter implosion shieid and the crt faceplate with a soft lint free cloth dampened with denatured aicohol The crt mesh filter furnished with Option 3 only can be cl
553. uit boards cannot be replaced A Follower board with contacts and interconnecting cables is replaced as a unit See Circuit Boards 1 Remove the A6 Main Interface circuit board from the instrument as previously described 2 Snap the white plastic connector cover off the side of the damaged plug in interface connector 3 Unsolder and remove the damaged contact 4 install the replacement contact Carefully position it to fit against the connector body 5 Snap the white plastic connector cover back onto the plug in interface connector Check that the replaced contact is aligned with the other contacts 6 Replace the A6 Main Interface board DELAY LINE REMOVAL The vertical delay line is carefully matched at the factory Therefore it is not recommended that repair be attempted in the field Instead contact your local Tektronix Field Office SEMICONDUCTORS Semiconductors should not be replaced unless actually defective If removed from their sockets during routine maintenance return them to their original sockets Unnecessary replacement of semiconductors may affect the adjustment of the instrument When semiconductors are replaced check the operation of circuits which may be affected E WARNING To avoid electric shock hazard always disconnect the 7904A from the power source before removing or replacing components Replacement semiconductors should be of the original type or a direct replacement The lead confi
554. uit that provides additional column current For example if a 10X attenuator probe is connected to a plug in unit encoded for 100 microvoits as shown in Figure 3 15 an additional unit of current is added to the column anaiog data during time slot 1 Since two units of current were encoded by R111 this additional cur rent results in a total of three units of column analog current 3 46 during this time slot Referring to the Character Selection Matrix three units of column current along with the two units of row current encoded by R10 indicates that the pre fix should be shifted one column to the left Since this in struction occurs in the same time siot that previously indicated that two zeros should be added to the display and oniy one instruction can be encoded during a time slot the zeros do not appear in the display The CRT readout will now be changed to 1mV readout program produced by plug in same as for previous example Three other lines of information are connected from the plug in compartments to the Readout System The column and row analog data from channel 2 of a dual channel plug in are connected to the Readout System through terminals A38 and B38 of the plug in interface respectively Force readout information is encoded on terminal A35 and the function of this input is described under Column and How Data Switches The preceding information gave a typical example of encoding data from an amplifier plug in unit Spec
555. ulator board An extracting tool should be used to remove the in line integrated circuits to prevent damaging the pins This tool is available from Tektronix Inc order Tektronix Part 003 0619 00 If an extracting tool is not available use care to avoid damaging the pins Pull slowly and evenly on both ends of the integrated circuit Try to avoid disengaging one end from the socket before the other end Hypcon Connectors The hypcon hybrid printed connector is a precision made connector designed to provide low loss electrical and or thermally efficient connection between the printed circuit board and hybrid integrated circuit An exploded view of the Hypcon connector is shown in Figure 4 14 Care must be taken when replacing the hybrid ICs not to touch the elastomer gold plated contacts with your fingers or to use a cleaner which wil degrade contact reliability If it becomes necessary to use a cleaning solvent near the connector when replacing adjacent within 1 2 circuit board components the Hypcon connector and hybrid IC should be removed IMPORTANT Remove all traces of solder flux or foreign material contamination from the circuit board contact area before replacing the connector Contamination usually takes place during the soldering and cleaning process Even when the soldering is done carefully flux oil or other contaminants can be carried under the connector during the cleaning operation When the solvent evaporate
556. ulse shaping network a current boost network and an operational amplifier The pulse shaping network comprised of transistor pair Q167 Q166 constant current source Q162 and adjustable components C150 R150 R155 C155 and C180 provides compensation to achieve a fast rising output pulse with optimum square ADD NOV 1985 corner current boost network comprised of common base amplifier Q173 and resistors R169 R176 and R177 provides a fast current path for the increased current needed to drive the DC Restorer network and the control grid of the crt The operational amplifier comprised of Q184 Q183 and feedback components R179 C179 maintains the output level of the Z Axis Amplifier during quiescent operation AUTO FOCUS CHANNEL SWITCH AND AMPLIFIER The Auto Focus Channel Switch and Amplifier stages provide control voltages to maintain optimum focus of the crt display When the front panel FOCUS control is set for best definition of the crt display at low to medium settings of the INTENSITY controls these stages maintain optimum focus for all portions of the dispiay as it is switched between the A and B Horizontal displays Transistors Q36 Q32 Q39 and Q50 act as a current driven data switch that provides the correct input to the base of Q67 of the amplifier stage This switch selects either the A Intensity B Intensity or Readout Intensity input as determined by the X Y Inhibit and Display B commands The input ou
557. ulti pin components must not be used Damage can void the warranty NOTE Some components are difficult to remove from the circuit boards due to a bend placed in each lead during machine insertion of the component The bent leads held the component in position during a flow solder manufacturing process which soldered all components at once To make removal of machine inserted components easier first remove the solder from the joint then straighten the leads of the components on the back of the circuit board using a small screwdriver or pliers When removing multi pin components do not heat adjacent conductors consecutively see Fig 4 9 Allow a moment for the circuit board to cool before proceeding to the next pin Bend the leads of the replacement components to fit the holes in the circuit board Insert the leads into the holes in the board or as originally positioned 2932 412 Figure 4 9 Recommended desoldering sequence Maintenance 7904A Touch the iron to the connection and apply enough solder to make a firm solder joint Cut off any excess lead protruding through the board Clean the areas around the solder connection with a flux removing solvent Be careful not to remove the information printed on the circuit board COMPONENT REMOVAL AND REPLACEMENT WARNING To avoid electric shock hazard and instrument damage always disconnect the instrument from the power source before removing or replac
558. unit removal instructions b Connect the line cord to the power source and Precision press the POWER button DC Voitmeter Connect the precision dc voltmeter DVM between TP 50 V Sense and TP Gnd Sense on the A22 Low Voltage Regulator circuit board d EXAMINE the meter for reading of 50 volts S Sa within the limits of 49 8 to 50 2 volts Appropriate range for voltage to be measured e ADJUST the 50 V adjustment R15 located on 1299501 the A22 Low Voltage Regulator Board for meter reading of 50 volts WARNING f iNTERACTION any change in the setting of R15 may affect the operation of all circuits in the instrument Extreme caution must be used when operating the 7904A with the power unit removed due to the line voltage high voltage and high currents present 5 36 4 POWER SUPPLY VOLTAGES NOTE If the preceding step was not performed first per orm step 1 then proceed A4 SETUP CONDITIONS 7904A Controis No change in settings Precision DC Voltmeter DVM Test Equipment Controls Precision DC Voltmeter DVM Approptiate range for voltage to be measured 4593 502 a EXAMINE Tabie 5 4 lists the tolerance of the low voltage power supplies in the 7904A Check each supply with the DVM precision dc voltmeter for output voltage within the given tolerance Connect meter common lead to TP Gnd Sense Test points are located on the
559. ust Calibrator TEKTRONIX TG 501 Time Mark 1 ns amplitude 0 5 V into 1 kHz Repetition Rate Generator and 500 series 50 stability within i Check and Adjust Horizontal Power Module one part in 10 Timing Length 18 inches Connect various signals Tektronix Part 012 0076 00 impedance 50 connectors bnc male 12 Coaxial Cable aee a tta MISI PV Hr Tama O SEHE rna Connect various signals Tektronix Part 012 0057 01 13 Coaxial Cable four needed Length 42 inches impedance 50 connectors bnc male Attenuation 2 Reduce amplitude of SG 504 Tektronix Part 011 0069 02 impedance 50 0 output accuracy 290 connectors bnc maie 1 bnc female 1 14 Attenuator 15 Adapter BNC T Connectors bnc male 1 Connect one signal to two i Tektronix Part 103 0030 00 bnc female 2 places impedance 50 0 MENT IER e j 16 Screwdriver Phillips Length of shaft 3 inches tip 2 Used to remove power Tektronix Part 003 0684 00 supply and rear panel BSh 17 Screwdriver Slotted Length of shaft 3 inches Adjust various controls i Tektronix Part 003 0192 00 width of shaft 3 32 inches 18 Tool Alignment Nylon Adjustment 5 64 inch Adjust 2 5 ns compensation Consists of maie hexagon on three inch Ha
560. v Triggering Auto AC internal 4593 514 Connect the CALIBRATOR output to the inverting vertical input of the test oscilloscope Set the test oscilloscope vertical deflection to display 4 divisions of CALIBRATOR signal Set the test oscilloscope for a stable display triggered on the rising portion of the CALIBRATOR signal Checks and Adjustment 7904A Part H Adjustment and Performance Check CHECK the displayed waveform for not more than 5 divisions horizontally between the 1096 to 90 points of the waveform rise time 0 5 microsecond or less Set the test oscilloscope for a stable display triggered on the falling portion of the waveform CHECK the displayed waveform for not more than 5 divisions between the 90 and 10 amplitude points fall time 0 5 microsecond or less Set the test oscilloscope triggering for positive slope and auto mode with ac coupling from the internal source at a sweep rate of 0 1 millisecond division Set the triggering controls so that the display starts at the 50 point on the rising edge of the waveform Set the test oscilloscope sweep magnifier to X10 Then position the display horizontally so the falling edge of the waveform aligns with the center vertical graticule line Set the test oscilloscope vertical to invert the display NOTE The disp ay is triggered on the opposite slope even through the display appears the same CHECK that th
561. vides the information necessary to 1 verify that the instrument meets the electrical specifications 2 verify that all controls function properly and 3 perform all internal adjustments Part i Performance Check verifies electrical specifications without removing instrument covers or making internal adjustments All tolerances given are as specified in the Specification tables section 1 in this manual A separate Operators Checkout Procedure is provided in Section 2 for familiarization with the instrument and also to verify that ail controls indicators and connectors function properly See Tabie 5 1 Checks and Adjustment Procedure Electives at the beginning of this section for information on performing a Partial Part II Adjustment and Performance Check procedure INDEX TO ADJUSTMENT AND PERFORMANCE CHECK PROCEDURE A POWER SUPPLY 1 Power Supply Preliminary Setup 2 Adjust Preregulator A12R93 3 Adjust 50 Volt Power Supply A22R15 4 Examine Power Supply Voltages t mor a on n B Z AXIS AND DISPLAY 1 Z Axis and Display Preliminary Setup 2 Adiust HV 208115 3 Adjust Z Axis DC Levels A21R135 alatus 4 Adjust Z Axis Transient Response A21C180 A21C150 A21C155 A21R150 Adjust Focus Level 21 70 Adjust Contrast A2R2015 Check Adjus
562. when this stored voltage exceeds about 80 volts However simply because the neon bulb is not flashing does not mean that the capacitors are fully discharged Remove the 7904A power cord plug from the power source Remove the protective cover from the power supply unit following the procedure under Access to Components in the Power Supply Unit Manually discharge the line storage capacitors using the procedure given later in this section under Access to Components in the Power Supply Unit Check the resistance of the power supplies at the test points given in Table 4 3 The Power Supply Test points are located on the A28 Horizontal Amplifier circuit board see Figure 8 1 NOTE Place the Common lead of the ohmmeter to ground when measuring power supply resistance if any of the resistance readings are significantly lower than that listed remove the electrical connections between the mainframe and the power supply unit Disconnect P17 P82 P83 on the A22 Low Voltage Regulator board This isolates the circuitry in the mainframe from the power supply unit Recheck the resistance If the readings remain low the malfunction is located within the mainframe circuits If the readings increase to normal or above the malfunction is in the power supplies Replace all electrical connections that were disconnected in part 5 4 10 TABLE 4 3 Typical Power Supply Resistance Typical Power Supply Ohmmeter Resistanc
563. with its subassemblies and parts precedes assembly 2 with its sub assemblies and parts Chassis mounted parts have no assembly number prefix and are located at the end of the Electrical Parts List TEKTRONIX PART NO column two of the Electrical Parts List Indicates part number to be used when ordering replace ment part from Tektronix SERIAL MODEL NO columns three and four of the Electrical Parts List Cotumn three 3 indicates the serial number at which the part was first used Column four 4 indicatesthe serial number at which the part was removed No serial number entered indicates part is good for ali serial numbers NAME amp DESCRIPTION column five of the Electrical Paris List in the Parts List an item Name is separated from the description by a colon Because of space limitations an Name may sometimes appear as incomplete For further item Name identification the U S Federal Cataloging Handbook H6 1 can be utilized where possible CODE column six of the Electrical Parts List indicates the code number of the actual manufacturer of the part Code to name and address cross reference can be found immediately after this page MFR PART NUMBER column seven of the Electrical Parts List indicates actual manufacturers part number 7 1 Replaceable Electrical Parts 7904A Mfr Code Manufacturer Address City State Zip Code 00213 5 COMPONENTS GROUP INC ORA
564. ws R 1 row 1 through 10 row 10 and R 14 row 14 can be addressed by the System Time Slot A location in a pulse train the Readout System the pulse train consists of 10 negative going pulses Each time slot pulse is assigned a number between 1 and 10 For example the first time slot is 5 1 Time Mulitplexing Transmission of data from two or more sources over a common path by using different time intervals for different signals DISPLAY FORMAT Up to 8 words of readout information can be displayed on the crt The position of each word is fixed and is directly related to the plug in unit from which it originated Figure 3 8 shows the area of the graticule where the readout from each plug in unit is displayed Notice that Channel 1 of each plug in unit is displayed within the top division of the crt and Channel 2 is displayed directiy below within the bottom division Figure 3 10 shows a typical display where only Channel 2 of the Right Vertical and B Horizontal units is selected for display Each word in the readout display can contain up to 10 characters although the typical display will contain between 2 and 7 characters per word The characters are selected from the Character Selection Matrix shown in Figure 3 9 addition 12 operational addresses are LEFT VERT RIGHT VERT CHANNEL 1 CHANNEL 1 A HORIZ CHANNEL 1 T i i i B HORIZ CHANNEL 1 Me
565. y No Effective Oscont Name amp Description TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL TERM TEST POINT BRS CD PL MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT LINEAR OPERATIONAL AMP JFET INPUT MICROCKT LINEAR AMPLIFTER M178 MICROCKT LINEAR VERTICAL OUTPUT MICROCKT LINEAR OPERATIONAL JFET INPUT MICROCKT LINEAR DUAL OPNL AMPL BUS CONDUCTOR DUMMY RES 0 094 0 BUS CONDUCTOR DUMMY RES 0 094 0 BUS CONDUCTOR DUMMY RES 0 094 0 BUS CONDUCTOR DUMMY RES 0 094 0 BUS CONDUCTOR DUMMY RES 0 094 00 D X 0 225 L D X 0 225 L D X 0 225 L D X 0 2251 X 0 225 L BUS CONDUCTOR DUMMY RES 0 094 OD X 0 225 L Mfr Code 80009 80008 80009 80009 80009 80009 80009 27014 27014 80009 80009 27014 04713 24546 24546 24546 24546 24546 24546 Mfr Part No 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 214 0579 00 LF351N GLEA134 LF35 N GLEA134 155 0175 05 155 0178 05 LF351N GLEA134 MC1458P1 MC1458U OMA 07 OMA 07 OMA 07 OMA 07 OMA 07 07 REV JUL 1987 Replaceable Electrical Parts 7904A Tektronix Serial Assembly No Mfr ent No Part No Effective Dscont Name amp Description Code Part No 19 570 1634 00 CIRCUIT BD ASSY HORIZONTAL INTERCONNECT 80009 670 1634 00 REMOVE FOR OPTION 02 REV JUL 1987 7 49
566. y output on one of ten lines REV NOV 1985 Theory of Operation 7904A corresponding to the column or row data encoded by the plug in unit These outputs provide the Column Digital Data and Row Digital Data which is encoded by the Decimai to BCD converters to create the address used by the Charac ter Generator in determining which character will be displayed The column and row data is also used throughout the Readout System to perform other functions The input current at pin 9 of the Column Decoder stage is steered to only one of the ten Column Digital Data outputs When a Display Skip signal is present collector of Q2229 pin 9 is pulled HI through CR2229 This ensures that no current is connected to the Character Generator stage un der this condition Notice the corresponding input on the Row Decoder This input is connected to ground and causes only one of the ten row outputs to saturate to ground The network at the input of the Row Decoder made up of Q2181 and its associated components is a Row 14 detec tor that produces the Jump Command This row current is encoded by special purpose plug ins to cause all or part of a word to be jumped Whenever row 14 13 units of row cur rent or 1 3 millamperes is encoded the base of Q2181 pulled negative enough so that this transistor is forward bi ased to produce a LO Jump Command output at its emitter The Jump Command is connected to the set input of RS flip flop U2162B wh
567. y remain unchanged When the Identify button is released the readout from this plug in channel is again displayed Circuitry may also be provided in the amplifier unit to produce a noticeable 2 10 change in the analog waveform display to identify the associated trace when the Identify button is pressed see the plug in unit manuals for details Readout intensity The READOUT contro determines the intensity of only the readout portion of the display independently of the other traces The Readout System is inoperative when the READOUT control is in the fully counterclockwise OFF position This may be desirable when the top and bottom divisions of the graticule are to be used for waveform display or when the trace interruptions necessary to display characters interfere with the waveform display Readout Modes The READOUT control determines the operating mode of the Readout System With the READOUT control set to free run out of OFF or PULSED detent positions the Readout System operates continually interrupting the crt display at random for about 20 microseconds in order to write each character on the crt With the READOUT control set to the PULSED position the Readout System operates in a triggered mode one complete frame up to eight words of readout is displayed The GATE EXT switch determines whether Readout is displayed at the end of the GATE or when an external signal is applied to the GRATICU
568. ystem Board and R O Center ad justment R737 on the A18 Vertical Amplifier Board to position the two rows of readout characters to the mid dle of the top and bottom divisions of the graticule Set Character Size adjustment R2210 on the A15 Readout System Board as desired EXAMINE display for two rows of zeros 40 zeros to each row Total length of each row of characters is be tween 9 5 and 10 divisions ADJUST RO Ctr adjustment R114 and RO Gain ad justment R101 on the A28 Horizontal Amplifier Board to horizontally center the zeros display and to set the length of each row of characters to between 9 5 and 10 divisions Set the POWER switch to OFF and repiace Plug 2184 on Pins 1 and 2 ADD NOV 1985 Checks and Adjustment 7904A Part Hi Adjustment and Performance Check G3 ADJUST CHARACTER CLOCK A15C2155 NOTE if the preceding step was not performed first perform step G1 then proceed G3 SETUP CONDITIONS 7904A Controls VERTICAL MODE 9 3 lt 3 a a Test Equipment Controis Amplifier Unit Defiection Factors 50 mV div Display Mode Dual trace 4593 546 Connect Test Osciloscope Channel 1 to pin 12 of U2202 on the A15 Readout System board Set the Time Base sweep rate for 5 uS div negative triggers Set the Amplifier Unit Trigger Source to CH 1 and con nect Channel 2 to pin 13 of U2202 ADJUST C2155 on A15 Readout System Board for seventeen positive pulses on the
569. zer Time Base 58 8B D f Time Base Test Leads Test Equipment Controis LEFT and A Signal Standardizers Vert or Horiz Gain 100 kHz RIGHT and B Time Bases Sweep Rate Triggering 2 us div Auto AC External Precision DC Voltmeter DVM Appropriate range for voltage to be measured 4593 508 a Set both signal standardizer Position controls to superimpose the crosshatch display over the vertical and horizontal graticule center lines b Set FOCUS control to midrange Temporarily set the POWER switch to OFF and remove the A20 High Voltage Board shield secured by three screws Connect the precision dc voltmeter DVM set to measure at least 36 volts between TP156 on the A20 High Voltage Board and chassis ground d Press the POWER button to on Set the VERTICAL MODE switch to ALT and the HORIZONTAL MODE switch to CHOP f EXAMINE the voltmeter for a reading of 34 to 36 volts ADJUST Shield Volts adjustment R155 on the A20 High Voltage Board for 34 5 volts on the DVM ADJUST the Focus Preset R55 on the A20 High Voltage Board and the front panel ASTIG adjustment R2025 on the A2 Display Control Board for the best overall resolution of the traces INTERACTION poor focus at one edge of the display may be improved by compromising the Shield Volts and Focus Preset adjustments parts g and Disconnect the precision dc voltmeter DVM Se

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