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1 - NSCA TRA-CAL

1. 61 Set the time base Time Div control to 500 ns Set the pulse generator to Both Paired by pressing both the Delayed and Undelayed pushbuttons together Set the pulse generator Variable Delay control so that one of the pulses in the CH4 display 66 occurs while the CH1 display is HI 67 and the other occurs while CH1 display is LO 68 Press the CLEAR pushbutton 69 the NOT pushbutton 70 the EDGE pushbutton 71 and the CH1 pushbutton 72 Notice that TRIGGER FUNCTION A is the falling transition of CH1 73 st gt nce 2 45 IFC Operating Instructions 7A42 Press the B pushbutton 74 and then the CH4 pushbutton 75 Adjust the time ae base Holdoff control for a stable display Vary the pulse generator Delay control and notice that a trigger is displayed on the TRIG VIEW trace 76 while the CH4 X pulse 77 is HI regardless of the CH1 signal 78 being HI or LO Set the pulse generator Variable Delay control so that one of the pulses is centered during the time that the CH1 signal is LO Now adjust the time base Holdoff control for an n unstable display 79 74 2 Ld T aj d 77 a wor E E on 5 d j e E a TM Oy Li pase QUO
2. 4285 219 2 14 fr m m en m w m m m m m m m mom m IF gu P sm rm hs dab ub ul du NI d s T l li dI dB ii ik TEM m Mm Nm ee V TW UN NN um pun pum quum cm pnm e in Operating Instructions 7A42 d Turn the oscilloscope mainframe Power off and then on again e After the self test is completed the 7A42 front panel status indicators and control lights should be as shown below O x TN PUN SWITCHONG TRE SHON mI i aj weur ENS Tektronix 7A42 85 217 42 2 15 Operating Instructions 7A42 EXERCISE 2 OBTAINING A TRIGGERED DISPLAY This exercise demonstrates basic triggering from a single oscilloscope calibrator signal A demonstration of the 7A42 front panel GAIN adjustment and how to obtain a triggered display on each of the four channels is also given NOTE If continuing from Exercise 1 proceed with Exercise 2 If not first perform Exercise 1 then proceed Now that the 7A42 is properly installed and initialized begin this exercise by performing the setup conditions as shown below COAXIAL CABLE CALIBRATOR CALIBRATOR TIME BASE TIME DIV TRIGGERING
3. 2 51 7A42 Front Panel Control Settings When Initialized 2 53 7A42 Operator Message Summary 2 55 Channel Volts Division Ranges 2 65 7A42 Operators OPERATORS SAFETY SUMMARY The general safety information in this part of the summary is for both operating and sevicing 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 Static Sensitive Devices A This symbol indicates where applicable cautionary or other information is to be found AS MARKED ON EQUIPMENT 4 DANGER High voltage Protective ground earth terminal A ATTENTION refer to manual vi Wl WI tm AIF iW wy Mi M
4. OPERATING INSTRUCTIONS This section will familiarize you with the capabilities and operation of the 7 42 A thorough understanding of this information will remove later uncertainty when operating your 7A42 OPERATION For operation your 7A42 Logic Triggered Vertical Amplifier must be properly installed in a Tektronix 7000 series mainframe Installation is explained in the Genera Information section of this manual SIMPLIFIED BLOCK DIAGRAM OF THE 7A42 The 7A42 has six basic functional blocks of circuitry Attenuators Amplifiers Channel Switching Trigger Threshold Generators Trigger Comparators and Trigger Logic see Fig 2 1 Each channel CH1 through CH4 has its own Attenuator Amplifier Trigger Threshold Generator and Trigger Comparator Impedance matching 500 1 0 and gain switching VOLTS DIV are accomplished by the Attenuator There are two signal outputs from each Attenuator one signal is applied to the Trigger Comparator and the other to the Amplifier for each channel The Amplifiers provide the signal gain necessary to drive the vertical amplifiers within the host oscilloscope mainframe The Channel Switching stage provides vertical signal processing to display the channel traces and the Trigger View trace on the mainframe crt This is accomplished by either chopping between the channels selected for display or by displaying them alternately after each sweep of the time ba
5. Deer rrrr Perr Irrr Function CH1eCH2eCH3 eCH4 Keystroke sequence NOT CH1 AND NOT CH2 AND CH3 AND CH4 Front panel Function TRIGGER FUNCTION display CH2 CH3 CH4 8 TRIGGER FUNCTION e ex L0 AND FLASHING CE Q LIGHT INDICATES EDGE EX reer rrrr Irrr rrrr TILI rrrr Frer rrrr rrrr L L L L H H H H H H H H Figure 2 3 Examples of products of Channel 1 through 4 TRIGGER FUNCTION display 2 5 Operating Instructions 7A42 r rrr L L L L H H H H H H H H Function CH1eCH2eCH3eCH4 reer rrrr rrrr rrrr rrrr rrrcr rrrr Function f rrrr rrrr rrrr rrrr IIIT Functlon g CH1eCH2eCH3eCH4 PEFR IIII rrrr rrrr rrrr rrrzr Function 8 Perr rrrr rrrr rrrr Function f g CH1eCH2eCH3eCH4 CH1eCH2eCH3eCHA4 Keystroke sequence CH1 AND CH2 AND CH3 AND CH4 OR NOT CH1 AND NOT CH2 AND CH3 AND CH4 Function Functlon 8 Function Front panel TRIGGER FUNCTION display TRIGGER FUNCTION eu ex Lo FLASHING LIGHT INDICATES EOGE QUALIFIED CH1 CH2 ANI 0 CHI CH4 eo 9
6. ocleo 06 oe Tektronix 7A42 MEE ae 4285 225 Press the GND pushbutton 24 again The CH1 GND indicator 22 is now extinguished and the baseline traces are replaced by the CH1 waveform 23 and the trigger view waveform 24 2 19 Operating Instructions 7A42 Press the PROG pushbutton 2 The pushbutton light is now green which indicates that the PROG TRIG Program Trigger mode has been selected Tektronix 7A42 Press the CLEAR pushbutton 26 and notice that the CH1 TRIGGER FUNCTION indicator 27 extinguishes the CH1 display 28 free runs is not triggered and the TRIG VIEW waveform 29 disappears This happens because there is no trigger function programmed so the time base unit does not receive a trigger signal ir Fi TE p dE IF i om 4 ug 4 H J i mm 1 9 mui i dm d in Fr im U uv dw 1 J Un iUm im Un ini Operating Instructions 7A42 Press the CH1 pushbutton 30 The C
7. To set the TRIGGER FUNCTION requirements for CH2 first select the Program Trigger mode by pressing the PROG pushbutton 79 so that it is lit green Press the CLEAR pushbutton 80 and then the CH2 pushbutton 81 Notice that the only TRIGGER FUNCTION indicator illuminated is CH2 82 and that the CH2 display 83 is triggered The TRIG VIEW waveform is also displayed 84 Bg soe vg 2 28 TU my wn vg IF A i m OIM ri nj HDI me Gd WwW Gh IRE UU IU IU IE IE T3 d LU Operating Instructions 7A42 Press the NOT pushbutton 85 and notice that the TRIGGER FUNCTION CH2 indicator 86 is green green TRIGGER FUNCTION indicator denotes an active LO trigger level Notice that the CH2 display 87 is triggered on the LO level of the calibrator signal 4285 042 ENS TektronN 7A4 2 Press the NOT pushbutton 88 again and observe that the TRIGGER FUNCTION CH2 indicator 89 is red and that the channel 2 display 90 is triggered on the HI level of the calibrator signal im 2 29 Operating Instructions 7A42 To set the vertical deflection factor of C
8. La hy dV a P 444 iE IB US N N D ut qe du ui us M UC iM at General Information 7A42 Characteristic SWITCHING THRESHOLD cont Hysteresis Centered at Threshold cont At tip of 10X probe with readout compensation TTL CMOS Family ECL Family Presets At tip of 10X probe with readout compensation TTL CMOS Family ECL Family PROBE OFFSET Activated TIP PROBE OFFSET Input Maximum Voltage Range Input Resistance DVM Resolution DVM Accuracy REV JUL 1984 TABLE 1 2 CONT Electrical Characteristics Performance Requirement TRIGGER CONT 5 10 V to 5 10 V dc only 20 mV 2 of reading Supplemental Information 400 mV 20 50 80 mV 20 50 1 4 V 1 30 V 0V 2100 20 mV 1 13 General Information 7A42 Characteristic TABLE 1 2 CONT Electrical Characteristics Performance Requirement Supplemental Information TRIGGER CONT TRIGGER FILTER Range Off or adjustable from 15 ns to 300 ns The trigger filter can not be activated if the EXT CLOCK is turned on nor will it operate with any trigger function that contains an edge sensitive channel Match Function A to Function B Within 2096 at maximum setting
9. c 5 4285 6 The TRIGGER FUNCTION requirements are now met and the CH1 display is again triggered 61 a Press the CH1 pushbutton 60 4285 237 2 25 Operating Instructions 7A42 Press the PROG pushbutton 62 for the PROG CHAN mode pushbutton light out Check the CH1 display for a 2 division square wave signal 63 If necessary adjust the 7A42 GAIN 64 front panel screwdriver adjustment for exactly 2 divisions of display position display as necessary 62 eie 4285 270 OP es Tektronix 7 42 Select CH2 for display by first pressing the CH2 pushbutton 65 and then pressing the DISPLAY pushbutton 66 Observe the CH2 base line trace 67 position as necessary The CH2 DISPLAY indicator 68 is illuminated red L eU gt oct munt om E QNEM wo s Q eres 4285 238 2 26 dp 4 Hi Ub o wu Ha 1 88 1 ar a T ka 1 1 UG IE 4 M j uj IU my mhi Pa ell Li Ll
10. E EM ENG JEN GU IRI E General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement Supplemental Information BATTERY BACK UP Ni Cad Battery 3 75 V Provides power to preserve front panel control status a minimum of 200 hours while main power is off Battery requires about 24 hours to fully charge from discharged condition TABLE 1 3 Environmental Characteristics Characteristics Information Temperature External Ambient Mainframe Temperature Operating 0 to 40 C in 7403N 7603 without fan fan kit is available 0 to 50 C in other 7000 series mainframes Storage 55 C to 75 Altitude Operating 15 000 feet 4 6 Km Nonoperating To 50 000 feet 15 2 Km EMC Tested to MIL T 28800C MIL STD 461A excluding RE 01 Vibration Operating and Nonoperating Shock Tested to MIL T 28800C SECT 4 5 5 3 1 Type Ill Class 5 Tested to MIL T 28800C SECT 4 5 5 4 1 Type III Class 5 1 21 General Information 7A42 TABLE 1 3 CONT Environmental Characteristics Characteristics Information Bench Handling Tested to MIL T 28800C SECT 4 5 5 4 3 Type Ill Class 5 Transportation National Safe Transit Association Preshipment Test Procedure Vibration and Boun
11. eo collec eoleo oolloo 4285 246 Tektronix 7A42 101 Select CH3 for display by first pressing the CH3 pushbutton 103 and then the DISPLAY pushbutton 104 Notice that the CH3 DISPLAY indicator 105 is illuminated red and that the CH3 deflection factor readout 106 is displayed on the crt Observe that the CH3 display 107 is not triggered This happens because no TRIGGER FUNCTION requirements are programmed for 4285 271 103 104 2 31 Operating Instructions 7A42 To set TRIGGER FUNCTION requirements for CH3 select the Program Trigger mode by pressing the PROG pushbutton 108 so that the pushbutton light is green Remove the CH2 TRIGGER FUNCTION by pressing the CLEAR pushbutton 109 Now press the CH3 pushbutton 110 Notice that the CH3 TRIGGER FUNCTION indicator 111 illuminates red Notice that the CH3 display 112 is triggered and that a TRIG VIEW signal 113 is displayed 108 111 Change the vertical deflection factor of CH3 by selecting the Program Channel mode press the PROG pushbutton 114 so that the pushbutton light is extinguished Press the upper VOLTS DIV pushbutton 115 once so that 0 2V is displayed on the crt readout 116 Check the CH3 trace 117 for a 2 division display 115 114 sa z E 428
12. owe z rs B 4285 267 2 46 rmm im care lm lm ii ws el sal ma bel ale lae le a a eae et eee rm m m pum Operating Instructions 7A42 Press the A THEN B pushbutton 80 and while varying the pulse generator Delay control notice that a trigger occurs on the TRIG VIEW trace 81 only on the leading edge of the first CH4 pulse 82 foliowing the falling edge of the CH1 trace 83 The display remains stable regardless of the setting of the time base Holdoff control L FLASHING omar Q weizares POSITION mune DEP ILI T 2 47 Operating Instructions 7A42 DETAILED OPERATING INFORMATION Detailed information concerning the controls and operation of the 7A42 is given in the following pages SELF TEST NOTE Disconnect any cables from the RESET EXT CLOCK and TIP inputs while Self Test is in progress an external impedance on these connectors may cause a Self Test failure When power is applied to the 7A42 an internal self test sequence is automatically performed While the self test sequence is in progress the mainframe crt readout shows 7A42 TEST BUSY see Figure 2 8 When the self test sequence is finished the message 7A42
13. Figure 3 4 Triggering low amplitude pulse prevent triggering on these normal transitions and at the same time allow the low amplitude pulse of a slightly longer duration to be detected Applications 7A42 APPLICATION 3 ADDING EDGE SENSITIVITY TO YOUR TRIGGER FUNCTION When developing a microprocessor based system it is important to ensure that data being read from or written into memory remains stable at specified times The 7A42 Logic Triggered Vertical Amplifier can monitor these data lines and trigger on an error condition by means of its level and edge sensitive Trigger Function features In addition to recognizing logic high and low levels the 7A42 can incorporate one edge sensitive channel into each product AND function Because each Trigger Function A or B can contain two products two independent Edge operators per Trigger Function are available Edge sensitive triggering can monitor data lines and check to ensure that the data remains stabile MEASUREMENT TECHNIQUE Figure 3 5 illustrates the timing requirements of a typical microprocessor read cycle The Data bus may change states during the first 200 nanoseconds of the Cycle but must remain stable during the final 100 nanoseconds while the ATA MUST BE STABLE DATA CAN CHANGE TRIGGER FUNCTION A 7 42 he 42 TRIGGER A THEN B GATE AT 7011 TRIGGER IN FILTER TIME TRIGGER FUNCTION B CAN TRIGGER 7011 DELAYED TRIGGER O
14. vedi eed On SOUree e eie eh dide Trigger Source Slope cire I Th eM RU one ER asa cer ex x SEERA SEER DC LEVEL i e ctis M etudes sb me edu AR Mette entation A IAS Preset Mainframe Settings A Trigger Left Vertical The 7D15 will keep a running count of the number of triggers generated by the 7A42 and display the total on the mainframe crt 3 11 Applications 7A42 COUNTING CLOCK CYCLES BETWEEN EVENTS The 7A42 s Trigger Function A and Trigger Function B can be programmed to recognize two independent events and the 7D15 will count the number of clock cycles occurring between the two events The 7A42 s A THEN B Gate out is sent to the 7D15 via the 7000 series mainframe trigger path This gate tells the 7D15 to count clocks on its input while the A THEN Gate is high To begin you must program the 7A42 s Trigger Function Start with Function A which will arm the 7A42 and cause the A THEN B Gate to go high when recognized Then enter Function B which when recognized will cause the 7A42 to generate a trigger and send the A THEN B Gate low Make the proper connections from the unit under test to the 7A42 s input channels set each channel for the desired logic family impedance threshold and display characteristics and enter the following 7D15 and mainframe settings 7D15 Settings C
15. us d we gor weur Tmeser out cue p 4285 255 Press the THRESH pushbutton 12 pushbutton light on Press and hold the 7A42 9 LEVEL control 13 and notice that the SWITCHING THRESHOLD display 14 increases from the default setting of 1 4 V Notice that when the SWITCHING THRESHOLD display reaches about 2 5 volts the amplitude of the displayed square wave signal 15 the displayed signal free runs is not triggered Press and hold the LEVEL pushbutton 16 until the display is again triggered 14 16 13 15 2 1 4285 256 Em Co 12 2 39 Operating Instructions 7A42 Press the TTL ECL pushbutton 17 twice and notice that the SWITCHING THRESHOLD display 18 defaults to 1 4 V The CH1 deflection factor also defaults to 5 V division 19 the minimum display size available Q mm H2 OMM VON MO eio Q wo CN qug Position rosimon See RR us oul Tektronix 7A4A s 17 257 Press the CH4 pushbutton 20 then press the DISPLAY pushbutton 21 Notice that the CH4 pushbutton 20 and the CH4 DISPLAY status lights 22 ar
16. APPLICATION 7 USING THE 7A42 WITH THE 7854 The TEKTRONIX 7854 is a waveform processing oscilloscope It combines the high performance of a 7000 series real time mainframe with digital storage and extensive processing capability 7A42 measurements with the 7854 are more accurate and faster than with a conventional oscilloscope The 7854 digitizes signals in up to 1 024 point records with 10 bit 0 01 division vertical resolution Single and dual cursors enable precise time and amplitude measurements Single keystrokes instantly calculate the most common waveform and pulse parameters e g risetime delay peak to peak etc Signal averaging will recover the true signal from noisy obscurity Up to 16 waveforms 40 with Option 2D can be stored and recalled for later measurement or comparison To digitize with the 7854 and 7A42 first ensure that the 7A42 is in the proper operational mode for the 7854 There is an internal jumper that must be properly positioned by qualified service personnel as detailed in the 7A42 Service Manual This ensures that readout and waveform acquisition will be consistent Valid display conditions for digitizing are 1 Any single channe displayed alone CH1 CH2 CH3 CH4 or TRIG VIEW 2 Channels 1 and 2 only displayed together ALT display mode selected 3 Channels 3 and 4 only displayed together ALT display mode selected Other channel combinations should be avoided for 7854 acquisitions Only a singl
17. IM IE n m Ifa IF 3 Operating Instructions 7A42 is An adjustment of the time base Holdoff control may be necessary for M Ps obtaining a stable display 1 A a a i PRATO iat a mo Q ann gt E SA me m d ibl ou u 1 PDT 3 A kG 4285 261 LAS 7A42 m 45 43 44 Set the time base Holdoff control so that the display is double triggered stable trace can now be obtained by using the 7A42 TRIGGER FILTER control Rotate the TRIGGER FILTER control 48 clockwise until the narrower of the two TRIGGER VIEW pulses 49 disappears 50 Now vary the time base Holdoff a control and notice that the display 50 is always stable Return the TRIGGER z FILTER control to the OFF counterclockwise detent position a a 77 77 a Ww wow P gt 9 oe 2 GAM make P 3 Gn wu 2 d Ll m x v ZEN Xt ELON INPUT pit m Q F m E z hfs a AERA NR 48 T 4285 262 2 43 a Operating Instructions 7A42 Press the NOT pushbutton 51 and notice that the CH4 TRIGGER FUNCTION indicator 52 is red active Hl
18. A EXT CLOCK Input Maximum Voltage Range 5V to 5V DC peak AC Threshold Two EXT CLOCK INPUT modes are available TTL or ECL for selec tion of either mode refer qualified service personne to 7A42 Service Manual TTL Level Logic Zero lt 0 8 V Logic One 22 V ECL Level Logic Zero lt 1 5 V Logic One 2 1 1 V 1 14 Vu ED VU HI VW JE L UJ uy iL 4 21 ut CI HG hb Y H lli Us IR ERR Mi um dm dm ui ub a gm iB 10 General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement Supplemental Information TRIGGER CONT EXT CLOCK Input cont Input Impedance The EXT CLOCK INPUT may be connected directly to the clock source or through a 1X probe TTL only The EXT CLOCK Input is not compatible with a 10X probe TTL Level Approximately 10K ohm in parallel with approximately 55 pF terminated to 5 V ECL Level Approximately 50 ohms terminated to 2 V Minimum Input None 100 mV ns Either pulse transition selected Leading pulse transition selected Trailing pulse
19. B I 7A42 Operators WARNINGS POWER SOURCE This product is intended to operate in a mainframe connected to a power source that will not apply more than 250 volts rms between the supply conductors or between either supply conductor and ground A protective ground connection by way of the grounding conductor in the mainframe power cord is essential for safe operation GROUNDING THE PRODUCT This product is grounded through the grounding connector 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 electrical shock DO NOT OPERATE IN EXPLOSIVE ATMOSPHERES To avoid explosion do not operate this product in an atmosphere of explosive gasses DO NOT OPERATE PLUG IN UNIT WITHOUT COVERS To avoid personal injury do not operate this product without covers or panels installed Do not apply power to the plug in via a plug in extender vii 7A42 Operators DESCRIPTION The 7A42 Logic Triggered Vertical Amplifier is a four channel wide bandwidth plug in unit compatible with Tektro
20. Mean value of square wave within one division of graticule center Risetime 10 to 60 2 ns tins Falltime 90 to 40 2ns tins Timing Time from Event A Recognition to Ris ing Edge 50 point of Gate Output Approximately 15 NS 4 Time from Event B Recognition to Fall ing Edge 5096 point of Gate Output Approximately 15 ns General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement TRIGGER CONT Supplemental Information Mainframe A THEN B Gate Output cont Pulse Width Gate Output width Measured at the 50 Points RESET Input Maximum Input Voltage Greater than the time between event A and event B by 5 ns 2 ns 5 V to 5 V DC peak AC Input Impedance Approximately 50 ohms Sse Levels Logic Zero 0 2 V Logic One 20 8 V Pulse Width 100 ns minimum Timing Post RESET Inhibit Time to Next Trigger Response Time 10 ns minimum Time from falling edge of RESET to next recognizable event RESET pulse must lead or be coincident with event recognition to inhibit trigger out put Event recognition must lead the RESET pulse by 10 ns to guarantee trigger output 1 20 TP m am m m n m aga m f mj m m m m m uo m ng S RS inl im iml IZ iz
21. Press the EDGE pushbutton 3 Notice that the CH4 TRIGGER FUNCTION indicator 82 is flashing to indicate EDGE qualified triggering Set the time base Time Div to 100 ns 54 Notice that the TRIG VIEW display has a narrow pulse 55 coincident with the rising edge 56 of the CH4 display 54 4285 263 Press the NOT pushbutton 57 Observe that the displayed TRIG VIEW pulse 58 now corresponds with the falling edge of the CH4 waveform 59 Adjust the pulse generator Variable Duration control and notice that the CH4 display becomes untriggered when the programmed trigger condition no longer exists CH1 AND NOT CH4 EDGE ine pee t EE 4285 264 2 44 ul qi CQ uS FY Ua H3 5 3 ga Gg IH Gg gn 1R Um li d 1 PY iio manh Gerke nce acd Ae eee cca addidi ml nail acl Operating Instructions 7A42 Press the NOT pushbutton 60 and the EDGE pushbutton 61 Notice that the CH4 TRIGGER FUNCTION indicator has stopped flashing 62 steady red and that the TRIG VIEW display 63 is HI during the time that CH1 64 and CH4 65 are both HI Set the pulse generator Variable Duration control for a CH4 pulse width of 100 ns CAL position 4285 265
22. SWITCHING THRESHOLD voltage CH1 though CH4 Preset TTL 1 4V display off THRESH Off PROBE OFFSET Off A TRIGGER FUNCTION CH1 HI B TRIGGER FUNCTION Cleared TRIGGER MODE TRIGGER FUNCTION A A THEN B Off EXT CLK SYNC Off External Clock Slope Off NOTE Controls not listed above are not preset 2 53 Operating Instructions 7A42 The battery backup feature can be defeated if so desired refer qualified service personnel to the 7A42 Service Manual If the battery backup feature has been disabled the 7A42 front panel control settings will return at power up to the settings listed in Table 2 2 and as shown in Figure 2 12 O Level Q 2 SWITCHING THAESHDLD fq in O Boome 2 a E VOLTS 7 PROBE OFFSET J TRIGGER FUNCTION DisPLAY POSITION O Fad mniset 0 0 2 2 Li asrar P0 EN O pow aS map O FAN OS 52 TRIGGER FILTER Q c POSITION or gt 300ns mo PX EXT CLOCK INPUT TRIGGER OUT O Q 5093150 O Tektronix 7A42 RNN en Figure 2 12 7A42 front panel control lights when initialized OPERATOR MESSAGES Operator Messages occur under several operating conditions and are accompanied b
23. 1 6 ENVIRONMENTAL CHATACTERS See Specifications 1 6 EVENTS COUNTING 3 10 EXAMPLES OF PRODUCTS 2 5 2 7 EXERCISES 2 13 2 47 EXCLUSIVE OR 2 3 EXT CLOCK INPUT 2 12 e 62 2 EXT CLOCK SYNC 2 12 EXT CLOCK SYNC SLOPE SELECT 2 61 index 7A42 FALLING EDGE SENSITIVITY 2 67 7 FIRMWARE VERSION NUMBER 2 49 FRONT PANEL CONTROLS 2 10 Initialization of 2 52 FUNCTION A 2 12 s FUNCTION 212 FUNCTION A THEN 2 12 E FUNGTIONAL CIRCUIT BLOCKS 2 1 GAIN 2 11 2 59 GET ACQUAINTED EXERCISES 213 GND 2 10 2 59 2 65 INPUT 2 10 2 59 2 65 1500 2 10 2 59 2 65 INSTALLATION 2 13 E INTIALIZATION 2 14 2 52 EE Control Ss 2 53 E LEVEL 2 65 266 TECHNICAL 5 MAINFRAME COMPATIBILITY 1 3 MESSAGES 2 48 2 54 7 MODE 216 FH 2 66 NOM RESET 2 12 2 63 3 7 Index 7A42 O OPERATING TEMPERATURE 1 3 OPERATOR MESSAGES 2 54 OPTIONAL ACCESSORIES 1 24 OPTIONS See Section 4 y tmp 2 3 2 10 2 67 PACKAGING FOR SHIPMENT 1 5 PHYSICAL CHARACTERISTICS 1 21 POSITION 2 10 2 59 PRESET THRESHOLD 2 65 PROBE OFFSET 2 66 3 16 PROBES 1 3 2 56 2 57 2 62 PROBE COMPENSATION 2 57 PROBING ECL 3 15 PRODUCT 2 3 2 67 PROG CHAN 2 10 PROG CHAN TRIG 2 10 2 64 PROG TRIG 2
24. E TRIGGER Pia uk me zr px AE FUNCTION CH1 CH2 CH3 CH1 CH2 CH3 Connect channels 1 2 and 3 to a suspected bus driver as shown in Figure 3 8 3 9 Applications 7A42 TRIGGER FUNCTION CH1 CH2 CH3 CH1 CH2eCH3 Keystroke sequence NOT CH1 AND NOT CH2 AND CH3 OR NOT CH1 AND CH2 AND NOT CH3 7000 SERIES OSCILLOSCOPE ENABLE LINE OF DATA BUS MAINFRAME VERTICAL MODE HORIZONTAL MODE B TRIGGER SOURCE 7B15 TRIGGER 7A42 TRIGGER FILTER ENABLE 00 NE BUFFER INPUT BUFFER TRIGGER VIEW TRACE Figure 3 8 Bus contention measurement set up 3 10 ig Applications 7A42 x APPLICATION 5 ENHANCED NESTED TRIGGERING USING THE 7D15 225 MHz UNIVERSAL COUNTER TIMER A ui The use of an oscilloscope to trigger on and display an event is helpful when trying to solve a problem Sometimes however a visual representation does not provide enough information to deal with the problem Additional data showing how much time has elapsed between occurrences of the event how many clock cycles separate the events and how many repetitions of the event occur in a given time interval can aid troubleshooting and reduce design time E uU ui Combining the nested triggering ability of the 7A42 with time frequency and events measurement capabilities of the 7D15 225 MHz Universal Counter Timer provides a powerful design evaluation and troubleshooting tool Usi
25. Fi IF Tm A m m m m m m m m rm p muUo om Un an B rumen ee ee ee rM MM MNT Vn n o t CI 8 i E D N T IU E General Information 7A42 TABLE 1 2 CONT Electrica Characteristics Characteristic Performance Supplemental Requirement Intormation TRIGGER CONT Mainframe Trigger Output cont Centering 1 MHz square wave Risetime 10 to 60 Mean value of square wave within one division of graticule center 2ns tins Falltime 90 to 40 2 ns tins TRIGGER OUT Connector Output Voltage Logic Zero 0 2 V into 50 ohm load Logic One Output Impedance 20 8 V into 50 ohm load Approximately 50 ohms Toggle Frequency 125 MHz maximum A Mode or B Mode with displayed input signal of 60mV p p ECL or 300mV in TTL Logic Family centered at threshold Propagation Delay Channel Input to Trigger Output Differential Propaga tion Delay from Channel Input to Trigger Output through any Trigger Function 25 ns or less 5 ns or less 1 17 General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement Supplemental Information TRIGGER CONT TRIGGER OUT Connector cont Propagation Delay cont A THEN B Mode Time Between 5 ns minimum Mini
26. 10 ae PROGRAM CHANNEL MODE 2 10 2 64 7 y PROGRAM TRIGGER MODE 2 10 2 66 m P6131 1 24 2 57 P6230 1 24 2 57 2 66 3 14 3 15 NS P6230 VARIABLE BIAS OFFSET 3 14 ae EE AE READOUT CRT 2 57 INPUT armed A THEN B r set 2 62 RELATED DOCUMENTATION 1 1 S SAFETY OPERATORS vl SELF TEST 2 14 2 48 SELF TEST FAILURE MESSAGES Illustration of 2 50 Table of 2 51 2 SELF TEST FAILURE CODE 2 50 SHIPMENT PACKAGING 1 5 SLOPE 2 12 gt SLOPE SELECT 2 61 SOFTWARE PERFORMANCE REPORT See front of manual Em x l i H 4 ad PER 1 i TEI mndex TAA2 SPECIFICATION 1 6 ELECTRICAL T6 ENVIRONMENTAL f 21 ii PHYSICAL 1 22 STANDARD ACCESSORIES RE 24 PDA E STATUS INDICATORS CHANNEL 2 59 2 SUM OF PRODUCTS NOTATION 2 5 SUM 23 E SWITCHING THRESHOLD VOLTS display 2 65 THRESH 2 10 2 65 2 66 TIME BASE PLUG IN 1 4 TIME BETWEEN EVENTS 3 12 NOME D TIME FROM FUNCTION TO FUNCTION B 212 TIP PROBE OFFSET 2 66 TRIG VIEW 2 10 3 2 TRIGGER FILTER 2 12 2 61 3 7 Application of 3 4 NIE T ds TRIGGER FUNCTION 2 12 oe EP ES Color red H green LO 2 80 s i RM ee TRIGGEERING NESTED 3 7 3 10 TRIGGER OUT 2 12 2 63 o Illustration of
27. 13 was taken without probes attached to the channel inputs and without changing the channel VOLTS DIV settings from those of Figure 2 14 2 57 Operating Instructions 7A42 Figure 2 13 Channel readout display 4285 218 Figure 2 14 Channel readout display with 10X probes attached to inputs of CH1 CH2 CH3 and 2 58 REV JUL 1984 51 Operating Instructions 7A42 NOTE The front panel controls indicators and connectors drawing Figure 2 7 in this section of the manual can be unfolded and referred to while reading the following text POSITION A POSITION control is provided for each of the four channels The control vertically positions the displayed trace on the host mainframe crt clockwise rotation moves the trace upward GAIN This screwdriver control adjusts the 7A42 display output of all four channels to match the vertical gain tolerance of any Tektronix 7000 series mainframe STATUS INDICATORS CH1 CH2 CH3 CH4 Each channel has four status indicators DISPLAY ECL TTL GND and 500 1 0 These indicators show the status of each individual channel A description of each indicator is given below DISPLAY When the DISPLAY indicator is lit the associated channel is displayed on the mainframe crt If the indicator is extinguished any signal applied to the channel input will still be routed to the TRIGGER FUNCTION circuitry providing the GND indicator is not lit ECL TTL
28. 2 59 1 7A42 Operators TABLE OF CONTENTS CONT OPERATING INSTRUCTIONS CONT Page STATUS INDICATORS CH1 CH2 CH3 2 59 DISPLAY o LS KERANE ape ese aie OF ores etd 2 59 ECEAT EE prit tgo me 2 59 tenete OS ERROR pas beatin ed E 2 59 tenerte ee eat erac Deu E eee 2 59 AET CEIOP reddent o t rides eiu ent eaa i eo 2 60 TRIGGER FUNCTION ccc cee nnn 2 60 A TRIGGER FUNCTION AND B TRIGGER FUNCTION 2 60 A THEN B NESTED TRIGGERING 2 60 TRIG VIEW i tuer rhet ere eee et Re at E Rep we 2 61 TRIGGER FILTER ct ree EO tag PEDI EMT NIU s 2 61 EXT CLOCK SYNC edd exe eter CO XE P RO e 2 61 SLOPE SELECT ts ani ver I EXER Red danda 2 61 EXT CLOCK INPUT acre endear pees eee chee va eed CA 2 62 RESET INPUT bebe en REPRE ee Y ERU 2 62 TRIGGER QUT uie ere tee rene outer e e P oe 2 62 PROG CHAN TRIG septa een emm phan Ree gay 2 64 PROGRAM CHANNEL MODE 2 64 CHAI CH2 CH3 CHAS oes ae 2 65 DISPLAY idis sant SE STR PS etm S A OE x e LAN 2 65 TTL7EGCLE ruat tepore m rer pre ee SR Mega 2 65 VOLT S DIVE A sea nr PDC pee tag Pre OGRE Man 2 65 GOR tk ihe rey EN C REA VCI OU aT SSS 2 65 1 xe E SAN LE SEE I prre peo 2 65 THRESH 4 urere Prem x ER ERAN nb Hao gar ce 2 65 PROBE OFFSET prm du ree a
29. 2 64 TRIGGER SPECIFICATIONS 1 11 2 10 2 59 J TTL ECL 2 10 2 65 VARIABLE BIAS OFFSET 8 14 VARIABLE THRESHOLD 2 66 4 VOLTS DIV 2 10 2 65 HER Application of 3 18 a I MEUM CL d Application of 347 M ee ape a 7011 DIGITAL DELAY ee Application of 3 7 pe al RE does 92 ys eet E gt pi wwe VU Pape ger Ud i RW ar as AM aa a oa ni 1 10 11 12 13 WARNI REV 7A42 Operator Messages Code Mnemonic OVERLOAD OFFSET ACQ PUSH PROG PUSH PROG AND OR REQ CH KEY REQ OR IS FULL EXTCLK ON EXTCLK REQ THRESH REQ Description and Corrective Action A channel input is overloaded Remove the overvoltage and unground the channels to continue operation A key was pressed while Probe Offset acquisition was in progress Push PROBE OFFSET once to lock in acquired value or twice to turn PROBE OFFSET off before continuing operation Key s pressed is are active only in PROG CHAN mode To use key first press PROG CHAN Key s pressed is are active only in PROG TRIG mode To use key first press PROG TRIG While programming a trigger function a CH1 CH2 CH3 CH4 NOT or EDGE was pressed when an AND or an OR key was expected While programming a trigger function two Boolean operator keys AND or OR were pressed without pressing a channel key CH1 CH2 CH3 or 4 in between Ch
30. 7A42 WITH THE 7854 APPLICATION 8 USING THE 7A42 WITH THE 7104 3 0 im qq ig HEH FH d SL DL I MI J I AR qe LN J E iM t n Lo eal edo nla ela a Ub T la APPLICATIONS In this section we give some examples of how your 7A42 Logic Triggered Vertical Amplifier can be used in specific applications These applications provide sufficient detail for you to adapt them to other related applications Contact your Tektronix Field Office or representative for assistance in making measurements that are not described in this manual APPLICATION 1 DISPLAYING FOUR CHANNELS OF DATA WITH THE 7A42 High speed delay comparisons and timing measurements on data lines are often difficult to accomplish with a high degree of accuracy However with less than 200 picoseconds time delay between any of the four input channels the 7A42 makes these measurements with ease and confidence For example the combinational triggering functions provided on the 7A42 front panel make it a simple matter to look at any count of a four bit counter A master clock signal can be connected to the 7A42 EXT CLOCK INPUT and displayed on the Trigger View trace MEASUREMENT TECHNIQUE Figure 3 1 illustrates an example of viewing the output of a counter when the countdown reaches a value of decimal 10 where the LSB
31. FILTER The TRIGGER FILTER control provides a selectable amount of delay between the time that the TRIGGER FUNCTION is recognized as true and the time that the Trigger Output is sent to the time base to trigger the sweep Thus the TRIGGER FILTER will inhibit trigger events that are shorter in duration than those for which the control is set A longer trigger event will pass through the TRIGGER FILTER and can cause a triggered sweep as well as a signal at the front panel TRIG OUT connector The TRIGGER FILTER control can be used only with level sensitive trigger functions it is inactive with any TRIGGER FUNCTION that contains an edge sensitive channel The TRIGGER FILTER operates independently on TRIGGER FUNCTION A and TRIGGER FUNCTION B In the A THEN B mode the TRIGGER FILTER may be inactive on function A because of an edge sensitive channel while at the same time be active on function B The TRIGGER FILTER is not active when in the EXT CLOCK SYNC mode or when the control is in the counterclockwise detent OFF position EXT CLOCK SYNC The EXT CLK SYNC pushbutton allows the 7A42 to be used in a synchronous mode of operation The trigger output in either A B or A THEN B mode will occur only on the selected edge of an external clock signal providing the TRIGGER FUNCTION is also true at that time If TRIG VIEW is selected a replica of the external clock input signal having a fixed amplitude and position will be displayed on the TRIG VIEW t
32. Figure 2 4 Function f and OR ed together 8 Ll A HERB RE E T 55 son 4285 208 dP qu wp Wa IF A M mp T m IF ge It fF ER p P P d Operating Instructions 7A42 If the first example of Figure 2 3 function f were programmed into the first column product of the 7A42 TRIGGER FUNCTION display and the second example of Figure 2 3 function g into the second the TRIGGER FUNCTION would be the sum of the two products as shown in Figure 2 4 The 7A42 has a feature called EDGE sensitivity Though a departure from pure Boolean logic this feature adds additional triggering flexibility by allowing the synthesis of additional digital circuit components such as flip flops Any product AND function in the trigger function can be programmed to have a single rising or falling EDGE sensitive channel That EDGE sensitive channel will then qualify the product only at the selected rising or falling EDGE sensitive channel transition Figure 2 5 shows a simple example of a product consisting of CH1 and CH2 where CH2 is selected to be rising edge sensitive Function CH1e1CH2 Keystroke sequence CH1 AND EDGE CH2 Front panel TRIGGER FUNCTION display p B Flashing A THENG FLASHING LIGHT RESET Vk lt son INDICATES EDGE
33. For instance the keystroke sequences CH1 NOT EDGE NOT CH1 EDGE and EDGE NOT are equivalent If the product already contains one edge sensitive channel at the time a second edge sensitive channel is entered into the same product the last entered channel will REV JUL 1984 2 67 in Operating Instructions 7A42 EE Pa receive the edge sensitive status The previous edge sensitive channel will become g level sensitive only This is because only one edge sensitive channel per product is T allowed If the last entered channel is converted back to level sensitive the previous p edge sensitive channel will again become edge sensitive E HY B IH m s Tw 2 68 ADD JUL 1984 MI NT m mI wy m MI HOR RRR PEPER N SECTION 3 CONTENTS APPLICATION 1 DISPLAYING FOUR CHANNELS OF DATA WITH THE 7A42 sever aceasta man Wore APPLICATION 2 SOLVING ABNORMAL PULSE PROBLEMS WITH THE 7442 D eI APPLICATION 3 ADDING EDGE SENSITIVITY TO YOUR TRIGGER FUNCTION APPLICATION 4 DETECTING AND DISPLAYING BUS GONTENTION io REM Ut APPLICATION 5 ENHANCED NESTED TRIGGERING USING THE 7015 225 MHz UNIVERSAL COUNTER TIMER APPLICATION 6 OFFSET PROBING TECHNIQUES FOR HIGH SPEED LOGIC APPLICATION 7 USING THE
34. Im irs m ee im 14 m TY re ta RT ME mr ER Operating Instructions 7A42 CONTROLS CONNECTORS AND INDICATORS All controls connectors and indicators required for the normal operation of the 7A42 Logic Triggered Vertical Amplifer unit are located on the front panel Figure 2 7 shows an exploded front panel and gives a brief functional description of each control connector and indicator Foldout for Front panel controls connectors and indicators Figure 2 7 2 9 Operating Instructions 7A42 1 PROG CHAN or TRIG Pushbutton selects one of two modes when ara _ light is on those controls associated with programming the TRIGGER FUNCTION are operable see 6 7 and 10 When light is out those i controls associated with CH1 CH2 CH3 CH4 setup conditions are operable see 6 and 2 5 LEVEL SWITCHING THRESHOLD Pe ad VOLTS TRIG VIEW 1 DISPLAY gn POSITION Q 509 9015 2 DISPLAY Pushbutton turns on or off the display of the incoming signal selected by controls listed under number 6 Nondisplayed channels may still contribute to the TRIGGER FUN
35. The EXCLUSIVE OR of variables X and Y is XeY Xey The AND OR NOT and XOR EXCLUSIVE OR logic functions are defined in Figure 2 1 for the constants O false and 1 true OR NOT 0 0 0 1 0 1 1 0 1 0 1 1 1 1 4285 206 Figure 2 2 Detinition of the Boolean AND OR NOT XOR EXCLUSIVE OR logic functions 2 3 Operating Instructions 7A42 5 The following two expressions known as DeMorgan s Theorem shows the relationship of the AND OR and NOT invert logic functions to one another With the use of the invert function the AND function can be expressed in terms of OR function and vise versa X Y XeY AND functions and OR functions can be combined together in one of two equivalent notations called sum of products and product of sums The 7A42 trigger function uses the sum of products notation that is the OR of two AND functions DeMorgan s Theorem can be used to convert from one notation to another An example of the sum of products notation as it reiates to the 7A42 is CH1 eCH2 CH3eCHA4 where CH1 CH2 CH3 and CH4 are the Boolean variables the two quantities in parantheses AND functions are called products and the two products are ORed together to form a sum Each 7A42 trigger function can consist of up to two products of the four input channels summed together The products may be formed in any combination from one or all of the input channels The analog channel
36. When the ECL TTL indicator is lit the channel threshold voltage range and deflection factors match the voltage levels and signal amplitudes of the TTL logic family When the indicator is extinguished the threshold voltage range and deflection factors are in accord with the ECL logic family GND When the GND indicator is lit the input to the selected channel amplifier is grounded and the signal path from the front panel bnc connector to the amplifier is open An external signal applied to this channel is not terminated it is open Grounded channel traces are stil displayed to enable the ground reference position to be established 50 1MO When the 509 1MN indicator is lit the input impedance of the associated channel is one megohm When the indicator is extinguished the input impedance is 50 ohms 2 59 Operating Instructions 7A42 ALT CHOP The ALT CHOP pushbutton selects either alternate or chopped as the display mode for all channels When the ALT CHOP indicator is lit the channels selected for display are alternately displayed on the mainframe oscilloscope crt after each sweep of the time base When the ALT CHOP indicator is extinguished the display is electronically switched between channels at about a one megahertz rate In general the ALT mode provides the best display at sweep rates of 100 microseconds division and faster while the CHOP mode provides the best display at sweep rates slower than about 200 microseconds
37. both drivers are enabled at the same time due to a circuit fault or poor design their outputs will contend with each other if they are attempting to establish high and low levels simultaneously In this situation an invalid logic level could exist and improper data could be transferred ui ut ux M 1 Bus contention also create a substantial power supply glitch This fault condition is very difficult to detect with an ordinary oscilloscope due to the aperiodic nature of bus activity Also the level and slope triggering system of a conventional oscilloscope provides no way of recognizing this type of condition ee eee i ul ut MEASUREMENT TECHNIQUE The 7A42 enables one to easily detect and trigger on a bus contention condition in order to trace the source of the error and isolate the problem When driver A is enabled CH1 low the signal at the input of driver A CH2 should match the signal on the bus line CH3 except for an instant of time equal to driver A s ui Meses ut propagation delay m Set the 7A42 to trigger when the above condition is not met that is when the input and output do not match At this time some other driver on the bus is E overpowering driver A s output The drivers propagation delay causes a mismatch that can be ignored by using the TRIGGER FILTER Control E Driver A s Driver A is input and output enabled do not match
38. division or whenever multiple single shot signals are to be photographed TRIGGER FUNCTION The two color TRIGGER FUNCTION indicators display the Boolean trigger function The color red indicates a logic 1 or higher than threshold voltage condition Green indicates LO logic or lower than threshold voltage condition An indicator that is not lit represents the X don t care condition A red flashing or green flashing indicator signifies that the channel is edge sensitive rising red or falling green as opposed to being level sensitive The TRIGGER FUNCTION indicators are arranged in two columns of four each Each column represents a logical AND function a Boolean product of the four input channels After the AND functions are performed the columns are ORed together to form the complete Boolean TRIGGER FUNCTION Thus each TRIGGER FUNCTION is equivalent to two four bit word recognizers ORed together There is one exception to this convention While an extinguished indicator represents the don t care condition an entire column that is not lit is considered to be inactive If an unlit column were interpreted as a don t care that column ORed with any other column would always be true A TRIGGER FUNCTION AND B TRIGGER FUNCTION There are two separate TRIGGER FUNCTIONS available A and B They are identical either may be used One pushbutton will always be lit to indicate which function is displayed by the TRIGGER FUNCTION i
39. during the time Self Test is running NOTE Before the 7A42 Self Test feature can verify that the 7A42 readout circuitry is operating properly mainframe crt readout system must be set to the Freerun non Gated mode DISPLAY MEDIA TYPICAL DISPLAY TRIGGER FUNCTION TRIGGER FUNCTION LEDS GREEN TEST PASSED RED TEST FAILED iasHing 243 LIGHT INOICATES aur O Q n uo ad level SWITCHING THRESHOLD oom VOLTAGE MONITOR Numeric Dispi ric Display VOUS CRT READOUT Numeric Display NOTE During some self tests the crt reedout is unstable this condition is normal FAILURE NUMBER 4285 215 Figure 2 11 Typical self test fallure display 2 bO REV JUL 1984 da ni Hd md H T BBA dj om H ML f SL o m x ab AH in 1 lal UN UNT ll UN Li a mr blk mmi rie apio anie uude clc ol Le acm us Operating Instructions 7A42 TABLE 2 1 7A42 Self Test Fallure Messages TRIGGER FUNCTION LED display T SWITCHING THRESHOLD VOLTS and crt readout display T Severity of failure functional usability of instrument Indication Test Indication Test CH1 ROM 01 to 04 R
40. edge qualified triggering and that the display is triggered on the rising edge of CH1 41 A slight adjustment of the time base Trigger Level control may be necessary to obtain a triggered display Notice that a narrow TRIG VIEW pulse 42 corresponding to the rising edge of the CH1 waveform can be observed with the time base Time Div control set to 100 ns div 43 FUEL ame UON du In O NS a CH3 m Pun gt Eu Ne POON is O botma byt Eui Le LOE 4285 231 2 22 as Las 141 fh I3 OO 3 3 4 Pg uL im Ud uv mati ki ut 1 un 1 Un 1 ik 1 I I I 1 1 1 1 4 1 I I Operating Instructions 7A42 Press the NOT pushbutton 44 the display is now triggered on the falling edge of CH1 45 and the CH1 TRIGGER FUNCTION indicator 46 is now flashing green mem 9 osm ay E SWHICHIMG dim d om PAOG rn i 2 Bosw on Q raan orcas ocr 1 7 oy ES UE L gt es 7A42 44 4285 23
41. for proper A THEN B operation Program function B then continue NG BEEPS Although no messages are displayed short warning beeps are issued to indicate out of range A beep will sound when the VOLTS DIV keys are pushed beyond the available selections or when the variable threshold level reaches its limits NOTE The audible beep can be turned off refer qualified Service Personnel to the 7A42 Service Manual Volume 1 JUL 1984
42. input is grounded and the input signal is electrically disconnected from the amplifier 500 1MOQ When indicator light is on the input impedance is one megohm 15 picofarads when off input impedance is 50Q GAIN Screwdriver contro adjusts display gain of channels CH1 CH2 CH3 and CH4 CH1 CH2 CH3 and CH4 Operate in either the PROG CHAN or the PROG TRIG modes In the PROG CHAN mode the self cancelling pushbutton switches determine which channel is affected by the controls listed under number 2 In the PROG TRIG mode the CH1 through CH4 pushbutton switches determine which channel is programmed into the TRIGGER FUNCTION as selected by the controls listed under number 107 CLEAR Pushbutton switch clears the programmed TRIGGER FUNCTION selected by the controls listed under 107 AND OR NOT Pushbutton switches used with controls listed under number 6 to program the TRIGGER FUNCTION selected by the controls listed under 10 EDGE Pushbutton selects edge sensitivity for the channel being programmed into the TRIGGER FUNCTION PROG CHAN TRIG must be set to CHAN PROG CHAN TRIG must be set to TRIG 2 11 Operating Instructions 7A42 TRIGGER FILTER Variable control sets minimum duration of TRIGGER FUNCTION output before it is sent to the time base or TRIGGER OUTput connector TRIGGER OUT Provides a front panel output of the trigger signal EXT CLOCK INPUT Provides external clock input for synchr
43. input signals become Boolean variables when they are compared to a threshold voltage If the signal is higher than the threshold it is true if lower it is false The Boolean variables may be programmed into the trigger function in either their non inverted high or inverted low form A channel input which is not part of the trigger function is considered a don t care Figure 2 3 shows two examples of a user programmed trigger function In each example the trigger function is comprised of a logical contribution of input channels 1 through 4 2 4 NOTE Logic symbols used in the following functional tables are of the positive logic convention and are defined as follows H high level true or logic 1 L low level false or logic 0 transition from low to high level transition from high to low level X irrelevant any input including transitions IL one high level pulse ne TE ino dal dn nb dn dul PH A TURNS DR AGES me o eim em Rr ou n RUN RUN NT Pp 1 i Operating Instructions 7A42 Function f CH19CH29CH3 CH4 Keystroke sequence CH1 AND CH 2 AND CH3 AND CH4 Front panel CH2 CH3 CH4 TRIGGER FUNCTION CHI e e CH2 Q AND ATHEN B FLASHING o Q Li elo nu zd RESET lt on CH3 LIGHT INDICATES EDGE QUALIFIED CH4 III rrrr IIII rrrr rrrr rrrcr
44. is displayed on the CH1 trace and the MSB is displayed on the CH4 trace To accomplish this enter the 7A42 Trigger Function NOT CH1 AND CH2 AND NOT CH3 AND CH4 The 7A42 can store and recall two independent trigger functions function A and function B To enter these two trigger functions press the A pushbutton enter the first Boolean trigger function equation push the B pushbutton and enter the second Boolean trigger function equation Either function may be recalled by merely selecting Trigger Function A or Trigger Function B When the input signals satisfy the programmed logic function the 7A42 will generate a trigger The trigger can be routed externally to other measurement devices and or internally through the 7000 series mainframe trigger path to a time base or special purpose plug in unit in either horizontal compartment No external connection to the time base is necessary to provide a triggered display on the oscilloscope crt The Trigger View trace enables you to see the state of the programmed trigger function in addition to the selected channel displays see Figure 3 2 The Trigger 3 1 Applications 7A42 View trace is a representation of the trigger signal output in the form of a small signal at the bottom of the crt This signal is sent to the time base and to the front pane TRIGGER OUT connector if the External Clock Sync mode is not in use The time registration accuracy of the Trigger View trace with the c
45. oil Li eli lil ell Ll ee Operating Instructions 7A42 Move the oscilloscope calibrator signal from the CH1 input connector 69 to the CH2 input connector 70 Notice that the square wave display 71 is free running not triggered Rotate the CH2 POSITION control 72 and notice that the square wave is displayed on CH2 The display 72 is free running because there is no TRIGGER FUNCTION 73 selected for CH2 and therefore the time base unit does not receive a trigger signal A base line trace is now displayed 74 for CH1 The base line trace is displayed on the crt because there is no longer a signal applied to the CH1 input connector Observe that the TRIG VIEW trace waveform is no longer displayed 75 because there is no longer a true TRIGGER FUNCTION and therefore the time base unit does not receive a trigger signal 73 x AN RO WE ao Q iau ok zn wa O Emus iC TE uiu Du TM meet TOY Q S 4285 239 2 27 Operating Instructions 7A42 To remove the CH1 trace from the crt display first press the CH1 pushbutton 76 and then press the DISPLAY pushbutton 77 Observe that the CH1 trace and deflection factor readout 78 are no longer displayed oo 4285 240
46. on the trigger view display 11 Set the CH1 POSITION control 13 to midrange 9 13 8 12 Q Bd o BR N 3 Sj Q Y iu yo Tektronix 7A42 4285 223 Press the DISPLAY pushbutton 14 and observe that the CH1 trace 15 is again displayed and that the TRIG VIEW trace 16 remains displayed at the bottom of the crt CHI e SZ wm O MES LA u Em onsite FUNCTION C ani 0 hasc n G o Dy Q Q SEU k uu cope vane on VA TA 2 2 m di Tektronix 7A42 2 18 18 ee ify df 4 H T Hd 4 i odd 1 lid It 19 i TH Ki d ti m lil Un 14 lai ATEM Un Operating Instructions 7A42 Press the GND pushbutton 17 Notice that the CH1 GND indicator 18 is illuminated and that the CH1 waveform 19 and TRIG VIEW waveform 20 are replaced by a baseline trace the CH1 input is now referenced to ground
47. reference 1 8 Hu UJ P HJ n T di ma 1 h Oh i ub IKI N B 1 1 B B Uu M US RO UC UC UU UD J Li eee i General Information 7A42 Characteristic tnput Characteristics cont High Impedance TABLE 1 2 CONT Electrical Characteristics Performance Requirement DISPLAY CONT 1 Megohm 1 in parallel with approx Supplemental Information imately 15 pF Low Impedance VSWR VOLTS DIV Shift POSITION Range Displayed Noise 50 ohms 1 ohm at dc 0 2 divisions or less shift when VOLTS DIV is changed in either TTL or ECL Families or between Families lt 1 15 1 de to 300 MHz At least 7 divisions to 7 divisions but less than 9 divisions to 9 divisions from graticule center with gain calibrated Grounded input at maximum sensitivity 7A42 triggered on another channel tested at 1 ms div and 10 ns div not more than 0 02 divisions RMS as measured in a 7854 DC Drift Drift with Time REV JUL 1984 Not more than 0 2 divisions in any 10 minutes after twenty minute warm up ambient temperature and line voltage constant 1 9 General Information 7A42 TABLE 1 2 CONT Electrical
48. transition selected Slew Rate TTL Level ECL Level Pulse Width TTL Level 20 ns minimum ECL Level 5 ns minimum 10 ns minimum Set up Time 10 ns minimum Time that level sensitive channels must be valid before EXT CLOCK INPUT transition 1 15 General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement Supplemental Information TRIGGER CONT EXT CLOCK Input cont Hold Time 10 ns minimum Time that level sensitive channels must remain valid after EXT CLOCK INPUT transition Channel EDGE Sensitivity Set up Time Channel to Channel 5 ns minimum Hold Time Channel to Channel 5 ns minimum Time that level sensitive portion of trigger function must be true before EDGE sensitive channel transition Time that level sensitive portion of trigger function must remain true after EDGE sensitive channel transition Set up Time EDGE Sensitive Channel 10 ns minimum Time that level of EDGE sensitive channel must be stable before transition Hold Time EDGE Sensitive Channel 5 ns minimum Time that level of EDGE sensitive channel must remain stable after transition Mainframe Trigger Output Amplitude 1 MHz square wave 300 mV 50 mV p p differential into A13 and B13 of main interface connection on left side of plug in 1 16 RI
49. used to connect gates the pull down resistor can also terminate the transmission lines which often connect gates This termination is usually 50 75 or 100 ohms connected to a 2V supply To probe ECL a 500 10X passive probe would be an attractive choice because of its very low input capacitance However this probe s resistance 500 to ground would form a voltage divider with the gate s output termination resistor Figure 3 9 shows an ECL emitter follower output stage being probed a by a standard 500 probe and b by the P6230 Variable Bias Offset Probe The divider can shift the ECL output signal levels with the low level affected most The dc operating point of the gate output transistor is substantially altered when the standard probe is part of the circuit as illustrated in Figure 3 9 The P6230 solves this problem by providing a bias voltage at the probe tip see Fig 3 10 For ECL circuit probing set the probe tip offset to the ECL low level or to the 2V termination voltage The effect of the probe s resistance on the gate s termination resistance will be minimized Figure 3 11 shows two superimposed waveforms Waveform B was taken using a 2 volt bias offset Waveform A was taken with no offset Notice the reduced level shift and faster negative transition of waveform B P6230 7 42 VARIABLE BIAS OFFSET Figure 3 10 Simplified diagram of the P6230 Variable Bias Offset probe 3 15 Applications 7A42 Fig
50. variety of grounding schemes are possible with the P6230 including a low inductance ground lead and a printed circuit board adaptor Ground leads should be as short as possible to minimize ringing The low capacitance of the probe makes it advantageous for probing transmission line circuits A high fidelity signal representation is possible with less sensitivity to the length of the ground lead than with higher capacitance probes STANDARD PROBE P6230 VARIABLE BIAS PROBE 5000 RESISTANCE OUTPUT TRANSISTOR TRANSISTOR OF ECL GATE TERMINATION OF ECL GATE TERMINATION RESISTANCE RESISTANCE 50 75 OR 1000 50 75 OR 4 A OUTPUT SIGNAL WITH B OUTPUT SIGNAL STANDARD PROBE WITH P6230 PROBE Figure 3 9 Standard 500 ohm probe forms voltage divider with termination resistor 3 14 d 4 1 4 5 E LEI uU A E F EB BI dE UD iN ii ulik Ar EET 11 Applications 7A42 PROBING ECL CIRCUITS ECL circuits are commonly operated with a 5 2 V and zero volt Vee and Vcc supplies For this configuration a high logic level becomes 0 8V and a low logic level becomes 1 7V The output of an ECL gate is the emitter of an NPN transistor emitter follower stage whose collector is connected to ground The output of the gate must be pulled down to a negative supply with an external resistor to enable proper logic levels to exist Transmission lines are often
51. 015 225 MHz UNIVERSAL COUNTER TIMER 3 11 EVENTS COUNTING iiisseees II ene 3 11 COUNTING CLOCK CYCLES BETWEEN EVENTS 3 12 MEASURING TIME FROM FUNCTION A TO FUNCTION B 3 12 APPLICATION 6 OFFSET PROBING TECHNIQUES FOR HIGH SPEED LOGIC SYSTEMS 3 14 PROBING ECL CIRCUITS posisi seas i a aa e 3 15 7A42 PROBE OFFSET FEATURE 3 16 APPLICATION 7 USING THE 7A42 WITH THE 7854 3 17 APPLICATION 8 USING THE 7A42 WITH THE 7104 3 18 1 INSTRUMENT OPTIONS INDEX CHANGE INFORMATION RELATED DOCUMENTATION For information on related 7A42 documentation refer to General Information Section 1 of this manual under Technical Manuals and Standard Accessories 7A42 Operators Figure No 1 1 1 2 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 2 10 2 11 2 12 2 13 2 14 2 15 2 16 2 17 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 3 10 3 11 LIST OF ILLUSTRATIONS Page 7A42 release late ELUCET da 1 3 7A42 dimensional 1 23 Simplified block diagram of the 7A42 2 2 Definition of the Boolean AND OR NOT and XOR EXCLUSIVE OR logic FURCHIONS ucc on RE epi SUMA ene aden i 2 3 Examples of products of Channel 1 through 4 2 5 Function f and g togeth
52. 10X passive high impedance probes are equipped with a compensation adjustment To ensure optimum measurement accuracy always compensate the oscilloscope probe before making measurements Refer to the probe instruction manual for probe adjustment procedure For optimum 7A42 P6131 performance the P6131 should be high frequency compensated while connected to the 7A42 see the P6131 probe manual for high frequency compensation adjustment procedure COAXIAL CABLES Although the 7A42 input channel VOLT DIV ranges are intended to be used with 10X probes coaxial cables may be used for signal connections When coaxial cables are used a 10X attenuator must be used to reduce TTL ECL signals to usable levels When 10X attenuators are used the VOLTS DIV and SWITCHING THRESHOLD readings are not automatically compensated and will indicate values a factor of 10 lower than actual Cables also may be used to connect signals to the input connectors but they may have considerable effect on the accuracy of the displayed waveform To maintain the original frequency characteristics of an applied signal use only low loss 50 ohm high quality coaxial cable Cables should be terminated into 50 ohms The 7A42 has an internal 50 ohm termination for each input channel which can be selected from the front panel CRT READOUT Figures 2 13 and 2 14 show the 7A42 scale factor readout location Figure 2 14 was taken with X10 probes attached to the channel inputs Figure 2
53. 2 Press the EDGE pushbutton 47 the display is now triggered on the LO level of CH1 48 The CH1 TRIGGER FUNCTION indicator 49 is no longer flashing two presses of the EDGE pushbutton cancel one another CH3 _ Q Pus ON ure Q CAN m y roti y i i oe Sine TRU 4 Hane 3 4285 233 2 23 Operating Instructions 7A42 Press the NOT pushbutton 50 to return the display triggering to the HI level of CH1 1 Set the time base Time Div control to 500 us 52 THI NI UU ELSE 3 d A RM ssi not 4285 234 Press the AND pushbutton 53 then press the CH2 pushbutton 54 and notice that the CH2 TRIGGER FUNCTION indicator 55 illuminates red CH1 56 remains red Notice also that the CH1 display is not triggered 57 This is because the TRIGGER FUNCTION requirements CH1 AND CH2 simultaneously HI are not met and therefore the time base unit does not receive a trigger signal 4285 235 2 24 gp Pd FI NI D g y Operating Instructions 7A42 Press the CLEAR pushbutton 88 the CH1 and CH2 TRIGGER FUNCTION indicators 59 extinguish
54. 259 2 41 Operating Instructions 7A42 Set the pulse generator Variable Duration control to display a 500 ns wide pulse on the CH4 display 32 Press the PROG pushbutton 33 so that it is illuminated green Program Trigger mode Now press the AND pushbutton 34 then the CH4 pushbutton 35 and notice that the CH4 TRIGGER FUNCTION indicator 36 is red indicating active HI level sensitivity for CH4 Press the TRIG VIEW pushbutton 37 and notice that the TRIG VIEW trace 38 is now displayed at the bottom of the crt Change the timing relationship of the CH1 and CH4 displays by varying the pulse generator Variable Delay control Notice that during the time that the CH1 39 and the CH4 40 displayed waveforms are both HI that the TRIG VIEW display is HI 41 Set the pulse generator Variable Delay control so the falling edge of the CH1 signal occurs while the CH4 signal is HI 42 Li LI H Jo 9 Press the NOT pushbutton 43 and notice that the CH4 TRIGGER FUNCTION indicator 44 changes to green active LO Now the 7A42 will produce a trigger when CH1 is HI and CH4 is LO Observe that the TRIG VIEW trace is H 48 when the CH1 display is HI 46 and the CH4 display is LO 47 Now adjust the pulse generator Variable Delay control so the HI level of the CH4 signal occurs entirely within the time that the CH1 signal 2 42 CJ W4 DC ar m i uq I3 Wp 53 dy R
55. 5 248 U B i JU Tektronix 7A42 2 32 mi Hha dL 4 Ii g w IE IE y TI Pu lx UR EET id Am ast m E U CAR B GE ue a Operating Instructions 7A42 To display Channel 4 press the CH4 pushbutton 118 and then press the DISPLAY pushbutton 119 Move the oscilloscope calibrator signal from the CH3 input connector 120 to the CH4 input connector 121 Observe that the channel 4 display 122 is not triggered The CH4 display is not triggered because no TRIGGER FUNCTION requirements have been selected for CH4 and therefore no signal is displayed on the TRIG VIEW trace 123 Notice that because there is no longer a signal applied to CH3 there is no longer a signal displayed on the CH3 trace 124 4285 249 2 33 Operating Instructions 7A42 To remove the CH3 trace 124 from the crt display first press the CH3 pushbutton 125 and then press the DISPLAY pushbutton 126 To set TRIGGER FUNCTION requirements for CH4 press the PROG pushbutton 127 Program Trigger mode Then remove the CH3 TRIGGER FUNCTION by pressing
56. CTION PROBE OFFSET Vpk ZI L ECL VOLTS DIV Two pushbutton switches increase or decrease vertical deflection factor of the channel selected by controls listed under number 6 DISPLAY POSITION TRIGGER FUNCTION GND Pushbutton grounds the selected channel amplifier input and fect en CHI Q Q disconnects the incoming signal of the channel selected by controls wi di listed under number 6 a 50g iwQ15pt CH2 Q Q ui 1M0Q 50Q Pushbutton switch selects input impedance to be either s one megohm or 50 ohms of the channel selected by controls listed under number 6 DISPLAY Q E nO POSITION AN 7777 Q TTL ECL Pushbutton switch selects the deflection factor range and y i preset threshold to be compatible with either TTL or ECL logic 4 GND 1 families of the channel selected by controls listed under number ts 509 1 15 a E SAN THRESH Pushbutton switch activates the LEVEL pushbuttons and di ANO SWITCHING THRESHOLD VOLTS display allowing operator to set V EXT CLOCK TRIGGER FILTER the threshold voltage of the channel selected by controls lis
57. Characteristics Characteristic Performance Requirement Supplemental Information DISPLAY CONT DC Drift cont Drift with Tem perature Not more than 0 2 divisions for 10 C ambient change line voltage constant Differential Delay Between Any Two Channels set to Same Logic Family and VOLTS DIV 200 ps maximum Plug in Delay Time Typically 25 ns from channel input to 11 and B11 of mainframe interface connector Channel to Channel Crosstalk Typically less than 0 05 divisions with logic signal inputs applied through a 10X probe Chop Frequency See mainframe manual for specifications TRIG VIEW or External Clock View Amplitude 0 35 divs 0 1 div Position Baseline to be set 3 divisions 0 5 divisions below grati cule center Internally adjustable approxi mately 4 divisions from graticule center Refer qualified service personnel to service manual 1 10 IF Fp FY IF mpm om yor rep IE ft I oF S 1 El i zi ut pig IN ui MI 1 6 ui TABLE 1 2 CONT Electrical Characteristics General Information 7A42 Characteristic Performance Supplemental Requirement Information DISPLAY CONT TRIG VIEW or External Clock View cont Risetime 2 ns or less Time Coincidence with Channel Display m TRI
58. ERED DISPLAY 2 16 EXERCISE 3 LOGIC TRIGGERING 2 36 DETAILED OPERATING 2 48 SELE TEST AOA ees eme A 2 48 FRONT PANEL INITIALIZATION 0 0 cece cece I 2 52 BATTERY BACKUP 21 UH ep dae 2 52 OPERATOR 2 54 SIGNAL CONNECTIONS cece ene ehe 2 56 CRT READOUT eae eee ar eed Se 2 57 POSITION estre xem ee RE OR ols OO EE OP CERTE A acl 2 59 GAIN x ciere tee E esa na duet ee a enu cL 2 59 STATUS INDICATORS CH1 CH2 CH3 4 2 59 ALT GHOP i e spe save rr MARII WE PURI e rO 2 60 TRIGGER FUNCTIONS oret tios oe nC UR RO 2 60 TRIG VIEW n cts RI eI RR oad eee eh aed AE 2 61 TRIGGER FILTER ineo eS vun sda pte e Pate ett PEE ado 2 61 EXT GLOCK SYNG Rb RN RRROCEE baw eae Rer iae 2 61 RESET INPUT wel hee eee 2 62 TRIGGER OUT ESSA vint Eds 2 62 PROG iis pA RR DE EE E ERE EEG 2 64 2 0 my um m om m m m M IF m m om m m m 19 r ep mq mi manksi meal UJ i UU d li us UJ 3 m Gi zx dd uis lod qund Gee cedo
59. Fr pra Fe i il j ee ee NEN tbe dk dil dbl lul lu s li idi lul du dul du EE ryp p pe mm v li a E a PURUS emm Operating Instructions 7A42 GET ACQUAINTED EXERCISES These Get Acquainted Exercises will help you become familiar with the operation of your 7A42 and at the same time check basic instrument operation The Get Acquainted Exercises are divided into three parts Exercise 1 Preliminary Set Up and Initialization Exercise 2 Obtaining a Triggered Display and Exercise 3 Logic Triggering NOTE When power is applied to the 7A42 an automatic self test will be performed After the self test is complete the display 7A42 TEST COMPLETE will appear on the crt for approximately 1 second If a 7A42 TEST BUSY message remains in the crt display see the discussion Self Test Failure Messages in this section under Detailed Operating Information EXERCISE 1 PRELIMINARY SET UP AND INITIALIZATION This exercise describes proper installation of the 7A42 into a compatible oscilloscope mainframe exercises the self test sequence and initializes the front panel control settings PRELIMINARY SET UP Perform the following procedure to install and power up the 7A42 a Install the 7A42 in the left two vertical compartments of a T
60. G VIEW Within 3 ns xi External Clock Within 5 ns View Readout Displayed on crt see detailed operating information TRIGGER M us Ee ee RJ MI 10 1 0 SWITCHING THRESHOLD Voltage Range At Input BNC TTL CMOS 1 28 V to 1 27 V Family ECL Family 256 mV to 254 mV At tip of 10X probe with readout compensation TTL CMOS 12 8 V to 12 7 V Family ECL Family 2 56 V to 2 54 V 1 11 General Information 7A42 Characteristic TABLE 1 2 CONT Electrical Characteristics Performance Requirement TRIGGER CONT Supplemental Information SWITCHING THRESHOLD cont Resolution At tip of 10X probe with readout compensation TTL CMOS Family ECL Family 100 mV 20 mV Accuracy at Center Value of Hysteresis Window At Input BNC TTL CMOS Family ECL Family 1 mV 2 of setting At tip of 10X probe with readout compensation TTL CMOS 5 mV 2 of setting 50 mV 2 of setting Family ECL Family Hysteresis Centered at Threshold 50kz 10 mV 2 of setting At Input BNC TTL CMOS 40 mV 20 50 Family ECL Family 8 mV 20 50 1 12 REV JUL 1984 IP IF 4 Fy E m gb IF im FE
61. H1 TRIGGER FUNCTION indicator 31 is now red indicating an active HI trigger level Both the CH1 waveform 32 and the TRIG VIEW waveform 33 are again triggered oe 7 o _ o GM i NE Paw Q m CHA abo J p A PS ini n Jj T7 puse e UAM 30 4285 229 Press the NOT pushbutton 34 Notice that the CH1 TRIGGER FUNCTION light 35 is now green and that the CH1 display 36 is triggered on the LO level of the CH1 signal The TRIG VIEW display is HI true when CH1 is LO false o oleo ee loo o E ee eo lleo e d Leta REV JUL 1984 E 2 21 Operating Instructions 7A42 Press the NOT pushbutton 37 Notice that the display is triggered on the CH1 HI level 38 and the CH1 TRIGGER FUNCTION indicator is red 39 two presses of the NOT pushbutton cancel each other ow lit ovum CN 3 80 f 17 ber LUCK INPUT IRIGGER au 4285 269 Set the time base Time Division to 100 ns and rotate the oscilloscope Intensity control clockwise to view the trace Press the EDGE pushbutton 40 Notice that the CH1 TRIGGER FUNCTION light is flashing to indicate
62. H2 select the Program Channel Mode by pressing the PROG pushbutton 91 so that the pushbutton light is extinguished then press the CH2 pushbutton 92 Press the upper VOLTS DIV pushbutton 93 once for a deflection factor of 0 2V as displayed on the crt readout 94 Check the CH2 display for a 2 division square wave display 95 V JO ano Q Q lt gt Q o cran 2 4285 244 To remove the CH2 display from the crt press the DISPLAY pushbutton 96 Notice that the CH2 DISPLAY indicator 97 extinguishes and the CH2 deflection factor readout 98 is no longer displayed Also notice that the TRIG VIEW trace 99 indicates that a trigger is still being produced This is because even though CH2 is not displayed the signal is still applied to the TRIGGER FUNCTION roomy dy US In ww 24 circuitry 2 30 IE Pw ms b al m In in it Int Ind TY AEE cep prm Ce meer Cale es ne Da ub db CUES OEERS umb egg qu oct UE AEF x 1 Operating Instructions 7A42 Move the oscilloscope calibrator signal from the CH2 input connector 100 to the CH3 input connector 101 Notice that the TRIG VIEW waveform 102 is no longer displayed 100 102
63. HRESH REQ Either a LEVEL key or the PROBE OFFSET key was pressed without pressing the THRESH key first The THRESH key must be lit to change a threshold level or acquire a probe offset 12 NO FUNC A The A THEN B key was pressed without having programmed function A or while in A THEN B mode function A was CLEARed Both trigger functions A and B must be programmed for proper A THEN B operation Program function A then proceed 13 NO FUNC B The A THEN B button was pressed without having programmed function B or while in A THEN B mode function B was CLEARed Both trigger functions A and B must be programmed for proper A THEN B operation Program function B then continue WARNING BEEPS Although no messages are displayed short warning beeps are issued to indicate out of range A beep will sound when the VOLTS DIV keys are pushed beyond the available selections or when the variable threshold level reaches its limits NOTE The audible beep can be turned off refer qualified Service Personnel to the 7A42 Service Manual Volume 1 SIGNAL CONNECTIONS Generally probes offer the most convenient means of connecting input signals to the instrument They are shielded to prevent electromagnetic interference The 10X probe offers a high input impedance to minimize circuit loading when measurements are made signal amplitude is attenuated by a factor of 10 by the probe so the scale factor readout is switched to ind
64. NDARD ACCESSORIES 1 24 OPTIONAL 1 24 PROBES oe eae dr aS 1 24 OPERATING INSTRUCTIONS 2 aa eor Pitas pe T P a ae ERE a 2 1 SIMPLIFIED BLOCK DIAGRAM OF 7 42 2 1 BOOLEAN ALGEBRA FOR 7 42 2 3 CONTROLS CONNECTORS AND INDICATORS 2 9 GET ACQUAINTED 2 13 EXERCISE 1 PRELIMINARY SET UP AND INITIALIZATION 2 13 PRELIMINARY SET eee een 2 13 INITIALIZATION e ee xr ca ee Rt en pe 2 14 EXERCISE 2 OBTAINING A TRIGGERED DISPLAY 2 16 EXERCISE 3 LOGIC TRIGGERING 2 36 DETAILED OPERATING INFORMATION 2 48 SELF TEST EI er ors RR lel ants saree EK p Re one 2 48 FRONT PANEL INITIALIZATION 00 2 52 BATTERY BACKUP irse RUPES LLL eS shea 2 52 OPERATOR MESSAGES 2 54 SIGNAL CONNECTIONS ete ee eens 2 56 RECOMMENDED PROBES 2 57 PROBE COMPENSATION 2 57 COAXIAL CABLES ler ei Poi RE ER ERE DEO 2 57 CRT READOUT eroi dete cat em ener ee A ET 2 57 POSITION ena dase be Heber hope weenie od 2 59 uu ie SERA VU
65. OM Possible loss first of front panel column control repair before use CH2 RAM 05 to 06 RAM first column CH3 Micro 07 to 09 Micro first processor processor column control contro logic logic CH4 10 Avoid use of first OFFSET OFFSET probe offset column feature 7A42 otherwise fully functional Repair when convenient CH1 Crt 11 Crt Channels 1 second display trace through 4 may column and display not be displayable readout Repair before use 12 13 Crt Crt readout may readout not be functioning Cause could be lack of mainframe readout Repair when convenient CH2 Trigger 14 Trigger Some or all trigger second control functions may not column be operational Repair before use 15 Trigger Some channels logic may not trigger properly Repair before use 2 51 Operating Instructions 7A42 TABLE 2 1 CONT 7A42 Self Test Failure Messages TRIGGER FUNCTION SWITCHING THRESHOLD Severity of failure LED displ LED display VOLTS and crt readout display functional usability Indication Test Indication Test of instrument CH2 Trigger 23 Boolean Some trigger Second cont logic functions may not column be operational cont Repair before use 26 A THEN B Avoid use of A THEN B mode Repair when convenient CH3 Edge 34 Edge Avoid use of second detectors detectors Edge qualified column triggering mode and external clock Repair when c
66. ON OR also serves as a delimiter for the CH1 through CH4 NOT and EDGE pushbuttons CLEAR The CLEAR pushbutton erases the TRIGGER FUNCTION program currently displayed by the TRIGGER FUNCTION indicators The other stored TRIGGER FUNCTION program remains unaffected by the CLEAR operation see A B and A THEN B NOT The NOT pushbutton is used to negate a variable in the Boolean TRIGGER FUNCTION For example if CH1 is entered into the TRIGGER FUNCTION display that is CH1 is an active HI red pressing the NOT key will change it to an active LO green Successively pressing the NOT key will alternately change the CH1 indicator from HI to LO this sequence will continue until a delimiter is entered AND or OR EDGE The EDGE pushbutton is used to change a level sensitive variable in a Boolean TRIGGER FUNCTION from level to edge sensitive The NOT pushbutton is used with the EDGE pushbutton to select falling edge sensitivity For example the keystroke sequence CH1 EDGE programs the 7A42 to trigger on the rising transition of CH1 the keystroke sequence CH3 NOT EDGE sets it to trigger on the falling transition of CH3 Pressing the EDGE key twice charges the channel to edge sensitive and back to level sensitive similar to the operation of the NOT key The 7A42 allows one independent EDGE sensitive channel per product in each TRIGGER FUNCTION A and B NOTE The channel CH1 CH2 CH3 or CH4 EDGE and NOT keys can be entered in any order
67. OURCE PULSE GENERATOR VARIABLE DELAY DURATION cbe Mae Matte Se E o samt ee dee 0 1 uS VARIABLE DURATION TRANSITION TIME TRIGGERING MODE A SUR UD S M aL DELAYED TIME BASE TIME DIV TRIGGERING INTERNAL CENTERED 2 37 Operating Instructions 7A42 Press the 7A42 upper VOLTS DIV pushbutton 1 twice for a 1V per division m deflection factor as shown on the Channel 1 crt readout 2 lt we Use the CH1 POSITION control 4 as necessary to move the square wave 3 r approximately 2 5 divisions in amplitude so that it can be viewed on the crt m EZ 4285 253 m Press the GND pushbutton 5 and notice that the CH1 GND indicator is now illuminated Use the CH1 POSITION control 7 to move the displayed trace to the graticule center line 8 4I m mem E en EX 4285 254 0 2 38 im HH C ng T TU ii eee eee T Operating Instructions 7A42 Press the CH1 GND pushbutton 9 and notice that the 2 5 division square wave 10 is displayed with its LO level near the ground reference 11 ave SWUCHAL THRESHOLD u 2 ndi wa is uS
68. POSITIVE CENTERED rm a m P re I mm quo id G UJ fk d 5 oO L i ee NN Gm l lil im limi ll liil i P Uaj lai Operating Instructions 7A42 As can be seen from the CH1 status indicators CH1 has been previously initialized to TTL 1 and 1 MQ 15 pf input 2 Observe that the TRIGGER FUNCTION has been set to trigger on a HI level of CH1 3 Rotate the CH1 POSITION control 4 to move the triggered display to the center of the crt ra HUM pur t Tektronix 7A4 ee 4285 221 Press the upper VOLTS DIV pushbutton 8 once to obtain a 0 2 V deflection factor as displayed on the crt readout 6 Note that the CH1 waveform amplitude increased 7 4285 222 2 17 Operating Instructions 7A42 Now press the DISPLAY pushbutton 8 note that the CH1 DISPLAY indicator 9 extinguishes and that the channel 1 waveform 10 is no longer displayed on the ert The trigger view trace 11 is now displayed at the bottom of the crt TRIG VIEW pushbutton is illuminated 12 Rotate the CH1 POSITION control 13 and notice that it has no affect
69. QUALIFIED errer L L L L H H H H 4285 209 Figure 2 5 Example of EDGE Qualified TRIGGER FUNCTION Another 7A42 feature is nested triggering One Boolean function programmed into the 7A42 s function A can be set to arm the trigger circuitry after which another Boolean function programmed into function can become the trigger event Without being previously armed by function A going true an occurrence of function B will not cause a trigger output pulse Figure 2 6 illustrates the A THEN B nested triggering mode 2 7 Operating Instructions 7A42 TRIGGER FUNCTION A fa CH1 CH2 Keystroke sequence CH1 AND CH2 Front panel TRIGGER FUNCTION A display TRIGGER FUNCTION eu CHI ex 9 Q ND ATHEN B RAsuNc t Q Q LIGHT INDICATES en EDGE QUALIFIED od Cor 7 TRIGGER FUNCTION B f CH3eCH4 Keystroke sequence NOT CH3 AND CH4 Front panel TRIGGER FUNCTION B display A TRIGGER FUNCTION e CHI Q 20 0 AND 8 ATHEN Li RESET lt 5 fusus CH3 LIGHT INDICATES EDGE Quarto CH2 CH3 CH4 NESTED TRIGGER Out 4285 205 Figure 2 6 Example of A THEN B Nested Triggering 2 8 4 1 Ak dH uH iH 3 1 4 94 17 M ir I l ik liad
70. TEST COMPLETE appears momentarily on the mainframe oscilloscope crt as shown in Figure 2 9 During the self test sequence some of the 2842 TEST Figure 2 8 Self test In progress Figure 2 9 Seif test finished 2 48 REV JUL 1984 IF i m UG p UJ n 3 W wy yp same i i n Operating Instructions 7A42 INDICATORS WILL LIGHT BOTH RED AND GREEN ALT TRIG CHOP VIEW ECL TTL Q POSITION DISPLAY TTL ECL IMR 5 DISPLAY POSITION um Q ATHEN B MRIS Q LIGHT osriay RESET GE Vok SV POSITION 0n ARN meo d 4 T QO G SAN OER TRIGGER FILTER DISPLAY LI e PDSITIDN OFF gt 300ns FX SY EXT CLOCK INPUT TRIGGER OUT P S SEE D Y Lx IMO isp Von 7 Pav LOGIC TRIGGERED lt lt VERTICAL AMPLIFIER Figure 2 10 7A42 front pane drawing showing pushbuttons and Indicators that are illuminated during the self test sequence front panel pushbuttons and all of the indicators are momentarily illuminated to verify their operation Figure 2 10 shows which ones should light The SWITCHING THESHOLD VOLTS indicator will display 8 8 8 8 during the first part of the self
71. UT 7A42 RESET INPUT 7011 TIME DELAY 200 nS Figure 3 5 Timing diagram of a typical microprocessor read cycle 3 6 qu oar ory IM Fg A A 0 UG UJ P A H m dl e e pm C Ub UC UC Ub Ud UD L i E ut ux Applications 7A42 microprocessor is actually latching the data in The 7A42 s A THEN B mode will be used to create a nested trigger function Trigger Function A must first arm the 7A42 before the next occurrence of Trigger Function will generate a trigger output signal In this application Trigger Function A looks for a low level on the read strobe but will not arm the trigger until the time selected by the TRIGGER FILTER control has elapsed Trigger Function B will then await any transition on the data line during the remainder of the strobe pulse The 7011 Digital Delay unit can be used to reset the Trigger Function if the error condition does not occur on a given read cycle For this measurement only two of the 7A42 input channels need be used CH1 can be connected to the memory Read line and CH2 can monitor the Data line The 7A42 will babysit these lines and trigger on any occurrence of either an invalid positive or negative transition on the Data line during a Read operation If the 7A42 produces no trigger signal the stability of the design can be assured If a trigger
72. alibrated setting eee Frequency Response Bandwidth 350 MHz in 7104 0 35 C mainframe am bient temperature Refer to Tektronix Product Catalog 7000 Series Oscilloscope System Specification for system bandwidths Input Signal Dynamic Range Maximum Signal Voitage at tip of 10X Probe TTL CMOS 30 V Family ECL Family 6 V Output Dynamic Range REV JUL 1984 Limited to the CRT display area Mainframe Vertical Trace Separation should not be used to bring an off screen signal onto screen 1 7 General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Requirement Supplemental Information DISPLAY CONT Maximum Input Voltage 1 Megohm 25 V dc peak ac 36 MHz or less derated linearly to 3 V peak ac at 300 Mhz 50 Ohm 5 V RMS during any 1 ms time interval Active internal protection opens all inputs if overvoltage is applied to any channel 50 Ohm Input Protec tion Reaction Time Maximum time to open input with applied overvoltage of 10 V DC 10 seconds 15V DC 1 second 20V DC 0 5 second Input Characteristics Input Coupling DC Incoming signal is dc coupled to the amplifier GND A grounded input is actually open at the input BNC i e 1 Megohm or 50 Ohm termination is dis connected Internally the amplifier input is grounded to provide a zero volt input
73. an be guaranteed with the following 7A42 display conditions 1 Any single channel displayed alone CH1 CH2 CH3 CH4 or TRIG VIEW 2 Channels 1 and 2 only displayed together ALT display mode selected 3 Channels 3 and 4 only displayed together ALT display mode selected Refer to the Applications section in this manual for further information 1 4 Wi fr Cw Ww mo wo m qam m oj m m m mn am m m m m om ma mie aes m m m im 1 M iM UM iM 1 ee ee a n um a ee gums General Information 7A42 PACKAGING FOR SHIPMENT If this instrument is to be shipped by commercial transportation we recommend 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 NOTE Package and ship Plug ins and Mainframes separately 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 package is unfit for use or not available package the instrument as follows 1 Obtain a corrugated cardboard shipping carton havin
74. annel keys and Boolean operator keys should be pressed alternately e g CH1 AND NOT CH2 OR CH3 EDGE The OR key was pressed again Only one TRIGGER FUNCTION OR is allowed The EDGE key was pressed while in the EXT CLOCK SYNC mode The selection of an EDGE sensitive channel and the EXT CLOCK SYNC mode are mutually exclusive If EDGE sensitivity is desired first turn off the EXT CLOCK SYNC mode The EXT CLOCK slope key was pressed when the EXT CLOCK SYNC button was turned off The EXT CLOCK SYNC slope key is operational only when the EXT CLOCK SYNC button is turned on The EXT CLOCK SYNC key was pressed when one of the trigger functions either A B or both already have an EDGE sensitive channel Channel EDGE sensitivity and EXT CLOCK are mutually exclusive If EXT CLOCK SYNC operation is desired first CLEAR the channel EDGE sensitive trigger function Either a LEVEL key or the PROBE OFFSET key was pressed without pressing the THRESH key first The THRESH key must be lit to change a threshold level or acquire a probe offset The A THEN B key was pressed without having programmed function A or while in A THEN B mode function A was CLEARed Both trigger functions A and B must be programmed for proper A THEN B operation Program function A then proceed The A THEN B button was pressed without having programmed function B or while in A THEN B mode function B was CLEARed Both trigger functions A and B must be programmed
75. ar or analogous to the ordinary algebra we use Expressions in both algebras consist of variables constants and operators The 7A42 provides oscilloscope triggering on Boolean or logical combinations of the input signals The input channels are the variables in the Boolean trigger equation and the 7A42 supplies the operators as programmed by the user The following is a brief review of the basics of Boolean algebra and an introduction to how they apply to the 7A42 Definition of Boolean logic functions 1 The dot is used to indicate the AND logical operator The AND function of two or more variables is sometimes referred to as a product It is the Boolean equivalent of ordinary multiplication In some Boolean expressions the dot may be omitted i e AeB AB 2 The plus sign indicates the OR logical operator which is sometimes referred to as a sum the Boolean equivalent of addition The AND function has mathematical hierarchy over the OR function as multiplication has over addition thus the expression WeX YeZ would be evaluated as if it were written WeX YeZ 3 A bar over a constant or variable is used to indicate the NOT logical operator Other words that are sometimes used to describe this operation are invert or complement X is the inverse or complement of X 4 A common Boolean function comprised of AND OR and invert operators is the EXCLUSIVE OR function symbolized by a plus sign with a circle around it 6
76. ce NSTA PROJECT 1 A B 1 packaged product Drop packaged product NSTA PROJECT 1 A B 2 TABLE 1 4 Physical Characteristics Characteristics Information Net Weight Approximately 6 2 Ib 2 8 Kg Dimensions See dimensional drawing Figure 1 2 mn m e o gm mo mg mm mm mmm mmm m m m m PP rm A 18 HI Oe ee ee S ee ga ga ee UJ in d lin General Information 7A42 NOTE DIMENSIONS ARE GIVEN WITH TOP FIGURE IN INCHES AND BOTTOM FIGURE N MILLIMETERS Figure 1 2 7A42 dimensional drawing 1 23 General Information 7A42 STANDARD ACCESSORIES LE Operators Manual lace bes S e alere a eg Service Manual Volume 1 ECCO Service Manual Volume 2 trace traces tech hern et ee SMB to BNC Cable For part numbers refer to the tabbed Accessories page at the rear of the 7A42 Service Volume 1 manual OPTIONAL ACCESSORIES not included The following accessories have been selected from our catalog specifically for your instrument They are listed as a convenience to help you meet your measurement needs For detailed information and prices refer to a Tektronix Products Catalog or contact your local Tektronix Field Representatives PROBES The P6131 10X passive probe 10 Megohm 10 8 pF has a 1 3 meter cable a narrow barrel and variety of probe
77. does occur the 7A42 will display the error condition Timing problems that recur at very slow repetition rates and happen rarely or at random can be viewed using a storage oscilloscope A fast writing rate real time oscilloscope can also be used with a camera to record the event Figure 3 6 shows how to set up the measurement and Figure 3 7 shows the display Tne 7A42 has captured a data line transition 10 nanoseconds before the end of the read cycle during the time that data should remain stable Notice that no trigger pulse TRIG VIEW corresponds to the falling data transition that occurrs 140 nanoseconds into the next read cycle because that data transition falls within the time that the data may still change Trigger Function A arms when a low level Read strobe occurs after the TRIGGER FILTER control time has elapsed Trigger Function B causes a trigger if during the remainder of the low level Read strobe either a positive or a negative transition of the data line occurs The variable TRIGGER FILTER control should be used to prevent arming before the time window of the actual Read operation The TRIGGER FILTER control can be set to prevent arming of the 7A42 for up to 300 nanoseconds For example with the TRIGGER FILTER control set for approximately 200 nanoseconds the Read line must remain low longer than 200 nanoseconds in order for Trigger Function A to be armed To set the TRIGGER FILTER control for 200 nanoseconds select Trigge
78. e as Se Scb ue dy bald eee 1 24 1 0 Qm wv w w m m m m m m m m m m m m m m m m m m m m m Bu d i 10 im im i D 1 lam 1 iu m ae T GENERAL INFORMATION This section contains a basic content description of both the Operators and Service manuals information on instrument installation power requirements packaging for shipment Standard Accessories Optional Accessories Specifications and a dimensional drawing of the 7A42 The specification portion consists of three tables Electrical Environmental and Physical Characteristics COLOR USED IN THIS MANUAL Red green and yellow color is used in this manual to visually correlate the front panel indicators and markings to the descriptions of the text TECHNICAL MANUALS An operators and two service manuals are supplied with your 7A42 as standard accessories The following information outlines the content of these manuals Operators Manual The Operators Manual is divided into the following four sections Section 1 GENERAL INFORMATION contains content descriptions of the Operators and Service manuals instrument description mainframe and plug in compatibility packaging instructions and instrument specifications Section 2 OPERATING INSTRUCTIONS contains a block diagram description a front panel drawing and brief descrip
79. e channel can be displayed when signal averaging Single channels displayed alone will always be acquired as the OWFM Channels 1 and 2 or 3 and 4 will always be acquired as OWFM and 1WFM respectively Trigger view may be acquired alone but it will be assigned the default vertical deflection factor of unity 1 division You may notice the readout format change as channels are displayed or removed from the display For example 1V may become 100 mV This is normal for a 7A42 in the 7854 operational mode and does not affect measurements 3 17 Applications 7A42 APPLICATION 8 USING THE 7A42 WITH THE 7104 The TEKTRONIX 7104 Oscilloscope is a one gigahertz mainframe that is an ideal companion to the 7A42 Logic Triggered Vertical Amplifier The bandwidth of the 7104 accommodates the full specified 7A42 bandwidth of 350 MHz for high speed logic An equally impressive capability is the fast writing rate of the 7104 microchannel plate crt At fast sweep rates the 7104 trace is much brighter than conventional oscilloscopes High transition pulses at low speed duty cycles can be easily seen under normal lighting conditions without the annoying baseline blooming as on conventional oscilloscopes The 7104 s crt brightness is particularly useful with the 7A42 High speed pulses are immediately apparent Trigger combinations that are seldom realized will still result in a bright usable display Additionally the 7104 is useful in co
80. e now illuminated red Notice that the CH4 deflection factor readout 23 is now displayed 2 40 4 eem s 777 Wu Seu J vons FUNCTION PERS QuT a L1 it g4 HH Hj IE BB CI 739 di nI IE Tj n E P b P E i Operating Instructions 7A42 Press the GND pushbutton 24 and notice that the CH4 GND indicator 25 is illuminated and that a baseline trace is displayed for CH4 Use the CH4 POSITION control 26 to move the CH4 trace to the second horizontal graticule line up from the bottom of the crt 27 This is the CH4 ground reference 120 wi O Q Bman O cC wo RR oe P QU E Bujwows E i 4285 258 Press the GND pushbutton 28 again and notice that the CH4 waveform is again displayed 29 Notice that CH4 is set for 5 V div 30 Set the pulse generator amplitude controls so that the most positive output level is 1 division 31 above the ground reference and the most negative level is at the ground reference 29 31 UE Li 9 Q 4285
81. ehh e ERU 2 66 LEVEL adn dier te donated Pei Ene uen EO PAR va ran 2 66 PROGRAM TRIGGER MODE 2 67 CH1 CH2 CH3 AND 4 2 67 AND oe ces iain ORAN led OER EUR 2 67 DR DER Pe Uem e E 2 67 CLEAR vetus Aid nena OR VAR n pte a Era 2 67 m 2 67 EDGE oes oy exero te Uf tuer a tach ents 2 67 APPLICATIONS 3 APPLICATION 1 DISPLAYING FOUR CHANNELS OF DATA WITHTHE eine eerte nm he ag Asa ese ie s xov e 3 1 MEASUREMENT 3 1 VIEWING THE MASTER CLOCK 3 2 APPLICATION 2 SOLVING ABNORMAL PULSE PROBLEMS WITHTHE 7TA42 eom qi a 3 4 MEASUREMENT 00 c cece mI 3 4 REV JUL 1984 ewm m a a o ow a m m em m a m m m m m m mm m m m gu uU UU iz ul C ee 7A42 Operators TABLE OF CONTENTS CONT APPLICATIONS CONT Page APPLICATION 3 ADDING EDGE SENSITIVITY TO YOUR TRIGGER FUNCTION cet e mess 3 6 MEASUREMENT 3 6 APPLICATION 4 DETECTING AND DISPLAYING BUS CONTENTION ecce eer bb 3 9 MEASUREMENT 3 9 APPLICATION 5 ENHANCED NESTED TRIGGERING USING THE 7
82. ektronix 7000 series oscilloscope mainframe e g 7104 7904 b Set the oscilloscope Vertical Mode to Left c Install a time base unit in one of the two horizontal compartments and set the oscilloscope mainframe Horizontal Mode for the appropriate time base A or B d Set the time base triggering to Slope Auto Mode with DC Coupling from the Internal Source and the Level control to midrange Set the time base Time Division to 1 millisecond f Set the appropriate oscilloscope mainframe Trigger Source A or B to Left Vert g Turn the oscillsocope mainframe Power on 2 13 Operating Instructions 7A42 NOTE Bold numbers are used as an aid to perform these exercises The number refers an instruction to an illustration The same numbers can be found in both the text and corresponding illustrations with an arrow pointing to a control indicator or crt display that has been mentioned in the text INITIALIZATION After completion of the 7A42 installation and power up self test sequence the next step is to initialize the 7A42 front panel settings To initialize the 7A42 front panel controls to a known state perform the following procedure a Set the PROG pushbutton 1 to the CHAN mode pushbutton light out b Press the THRESH pushbutton 2 so that the pushbutton light is on Threshold Mode c Press the PROBE OFFSET pushbutton 3 until it illuminates red Acquire Mode we
83. el display with an external clock signal displayed on the TRIG VIEW trace 3 3 Applications 7 42 APPLICATION 2 SOLVING ABNORMAL PULSE PROBLEMS WITH THE 7A42 Defective gates or timing errors in a logic system can produce low amplitude pulses which are not recognizable as valid logic levels These abnormalities can introduce errors in the performance of a digital system which are very difficult to trace and locate To an ordinary oscilloscope triggering system one pulse in a pulse train looks like any other The oscilloscope can only recognize a pulse which has a higher than normal amplitude A low amplitude pulse can be difficult if not impossible to detect Low amplitude pulses or half logic levels can be detected by means of the 7A42 variable threshold feature Each of the four channels have a distinct threshold recognition level for a high or low logic level The 7A42 features an automatic preset TTL or ECL threshold level If a variable threshold is needed enter the Program Channel mode turn the threshold monitor on and select the channel whose threshold is to be varied The LEVEL and LEVEL controls can then be used to set the desired threshold voltage The threshold voltage for each channel can in turn be set individually in this manner MEASUREMENT TECHNIQUE When one wants to trigger on a pulse that is somewhere in the TTL threshold region 0 8V and 2 0V a problem arises because the pulse is t
84. er 2 6 Example of EDGE Qualified TRIGGER FUNCTION 2 7 Example of A THEN B Nested 2 8 7A42 controls connectors and indicators 2 10 Self test in 55 2 48 Self test 2 48 7A42 front panei drawing showing pushbuttons and indicators that are illuminated during the self test 2 49 Typical self test failure 2 50 7A42 front panel control lights when initialized 2 54 Channel readout 2 58 Channel readout display with 10X probes attached to inputs of CH1 CH2 CH3 and 4 2 58 Timing diagram showing the relationship of the TRIGGER OUT waveform to the input 5 0 5 2 63 Timing diagram depicting the TRIGGER OUT waveform as a result of the TRIGGER FUNCTION reacting to the input signals 2 63 Example of A THEN B level and EDGE sensitive TRIGGER FUNCTION showing the Normal and A THEN B Gate waveform alternatives 2 64 Triggering the decimal 10 3 2 Display of four channels with TRIG VIEW 3 3 Four chan
85. g inside dimensions at least six inches greater than the instrument dimensions refer to Table 1 1 for carton test strength requirements 2 Enclose the instrument with polyethylene sheeting or equivalent to protect the finish of the instrument 3 Cushion the instrument on all sides by tightly packaging dunnage or urethane foam between the carton and the instrument allowing three inches of packaging 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 TABLE 1 1 Shipping Carton Test Strength Gross Weight Ib Carton Test Strength Ib X 0 200 10 30 275 T 30 120 375 120 140 500 1 5 General Information 7A42 SPECIFICATION The electrical characteristics listed in Table 1 2 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 is allowed a 20 minute warm up period 3 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 3 5 the instrument must be operated in a calibrated 7000 series mainframe Any applicable conditions not listed above may be stated as part of the characteristic Environmental characte
86. hannel display s makes it useful in verifying when the programmed trigger condition indeed exists The Trigger View trace can also be used to measure how long the trigger function is true Viewing The Master Clock Line The Trigger View trace can display a fifth channel of data such as the master clock see Figure 3 3 Applying the master clock signal to the EXT CLOCK INPUT 7000 SERIES OSCILLOSCOPE TIME BASE UNIT 23 7 42 TRIGGER TRIGGER FUNCTION GH1eCH2 CH3eCH4 2 e23 DECIMAL 10 Keystroke sequence NOT CH1 AND CH2 AND NOT CH3 AND CH4 Figure 3 1 Triggering on the decimal 10 event 3 2 1R A H A 1 eu IF pB Ej ere FR 3 Applications 7A42 enables the user to 1 Qualify the Trigger Function on a positive or negative transition of the external clock input signal and 2 display that clock signal by selecting the Trigger View trace pun i 8 ud TRIGGER FUNCTION CH1 CH2eCH3 CHA MJ 4285 303 ih uM Figure 3 2 Display of four channels with TRIG VIEW trace uL TRIGGER FUNCTION CH1 CH2 CH3 CH4 Keystroke sequence NO CH2 AND NOT CH3 AND WERT uem a ERN m IM UC UC UL TRIGGER EXTERNAL CLOCK SIGNAL Figure 3 3 Four chann
87. he 7A42 The probe offset button will now light green and the probe tip may now be removed The offset measurement remains in the display which is again indicating the SWITCHING THRESHOLD voltage At this point the SWITCHING THRESHOLD can be adjusted to any other value independent of the probe offset by using the LEVEL buttons Pressing the PROBE OFFSET button once more turns off the lit button clears the acquired offset measurement and reestablishes the preset threshold The 7A42 PROBE OFFSET feature is appropriate for use only with the P6230 probe The acquired PROBE OFFSET voltage whether zero or otherwise is maintained when the THRESH button is turned off or while threshold information of another channel is being displayed That value is also maintained if the logic family is changed the switching threshold reverts to the probe offset voltage If a channel has a non zero offset the PROBE OFFSET button will be lit green when that channel is selected PROG CHAN mode as a reminder of the offset status LEVEL The LEVEL and LEVELS controls are used to set the threshold voltage of each channel to a value other than the preset threshold voltage These controls are active only in the PROG CHAN mode and when the THRESH pushbutton switch is lit When either the or LEVEL button is held the variable threshold changes at an accelerating rate pausing momentarily at the preset value There will be no pause if a probe offset has been acqui
88. he equipment listed below was used to develop this exercise Other equipment may be substituted for instance any Tektronix 7000 series time base or oscilloscope any Tektronix 10X voltage probe and any pulse generator with both a trigger output and a delayable pulse output capable of producing zero to 2 volts from the trigger out and 5 volts from the pulse out Oscilloscope Tektronix 7904A one required Time Bases ud nr i ae Tektronix 7B10 one required Subminiature probe tip to bnc adapter Tektronix Part 013 0195 00 two required Probe licut okie ya UP eae Tektronix P6131 two required Pulse Tektronix PG508 installed in a Tektronix TM503 one each required NOTE First repeat Exercise 1 then proceed 2 36 JE Ay IH H H H9 T GY gy EF 73 IF TE TW Uu OA TENER za l lac 4 TU lx lo Operating Instructions 7A42 Perform the following setup OSCILLOSCOPE TIME BASE PULSE GENERATOR PULSE TRIG BNC TO PROBE TIP ADAPTOR OSCILLOSCOPE POWER VERTICAL MODE HORIZONTAL MODE TRIGGER S
89. iB IH J 1B al ee ee cd H otk ru i d d iB dm Au M Ew Ara Tie e ti teet uer Ug uis om Dey a tte GS m iB ED d i d T E K OPERATORS PRODUCT GROUP 42 MANUAL 070 4285 00 7A42 Logic Triggered Vertical Amplifier Please check for change information at the rear of this manual First Printing APRIL 1983 Revised JUL 1984 Tektronix COMMITTED TO EXCELLENCE DIGITALY REMASTERED OUT OF PRINT MANUAL SCANS By Artek Media 18265 200 St Welch MN 55089 www artekmedia com High resolution scans of obsolete technical manuals If your looking for a quality scanned technical manual in PDF format please visit our WEB site at www artekmedia com drop us an email at manuals artekmedia com and we will be happy to email you a current list of the manuals we have available If you don t see the manual you need on the list drop us a line anyway we may still be able to point you to other sources If you have an existing manual you would like scanned please write for details This can often be done very reasonably in consideration for adding your manual to our library Typically the scans in our manuals are done as follows Typed text pages are typically scanned in black and white at 300 dpi 2 Photo pages are typically scanned in gray scale mode at 600 dpi Schematic diagram pages are typically scan
90. icate the correct scale factor The limited TTL ECL VOLTS DIV ranges require that attenuation be used to obtain useful signal levels at the 7A42 channel inputs Ten times probes are recommended on the channel inputs to attenuate TTL and ECL signals otherwise 10X attenuators should be used When 10X probes are used the VOLTS DIV and SWITCHING THRESHOLD are automatically compensated to reflect the characteristics at the probe tip 2 56 ef Iri 13 Gd ERI id E EI i lai amisi NN EN lM ur uf dno uv dm um us daB dE dE pac eae a aoi LU Operating Instructions 7A42 RECOMMENDED PROBES The Tektronix P6131 and P6230 probes are recommended for use with the 7A42 The Tektronix P6131 is a 10X passive probe with 10 megohm at 10 8 picofarads A variety of probe tips hooks IC grabber and ground leads are available with this probe The Tektronix P6230 is an active 450 ohm bias offset probe which is especially useful with ECL logic circuits due to its minimal circuit loading characteristics For information on how to use the P6230 probe refer to the Application section in this manual Probe Compensation Maladjustment of probe compensation is one source of measurement error Most
91. ications 3 12 im wa Ti T4 Th H8 HM CI FI iy T 1 Applications 7A42 ps _ 7015 Settings p Gate o order padece ors Ample E Er aque Normal EP AME MR A NOEL TIM Width A VEN X10 Re ream RU bx ed 10 ns Trigger A SOURCE Trigger Source s SIOPE t tote Coupling nere eR EX Br crest hee quere DC Level 3 E EE etas Preset Mainframe Settings Set the Trigger Source for the compartment containing the 7D15 to Right Vertical T ipl 3 13 Applications 7A42 APPLICATION 6 OFFSET PROBING TECHNIQUES FOR HIGH SPEED LOGIC SYSTEMS Probing high speed circuits with high impedance probes can cause ringing at high frequencies and significant degradation of rise and fall times The 7A42 Logic Triggered Vertical Amplifier P6230 Variable Bias Offset Probe combination enables probing high speed ECL logic with minimum circuit loading The P6230 Variable Bias Offset Probe is a 10X 450 ohm device The bias voltage at the probe tip is continuously variable from 5V to 5V It also features a built in 50 ohm termination resistor that can be switched in for use with 1 megohm amplifiers This 50 ohm termination will be switched out in this application in favor of the 7A42 s internal 50 ohm terminator A
92. ily there are internally preset thresholds that can be altered by pressing either the LEVEL or LEVELS button A single push changes the threshold by one increment When either LEVEL button is held down the rate 2 65 Operating Instructions 7A42 accelerates Each channel s threshold level is maintained when THRESH is pushed again to turn off the seven segment display and button light However for a particular channel the variable setting if any will be cancelled reverts to the preset value when the TTL ECL selection is changed PROBE OFFSET The PROBE OFFSET control provides a means of acquiring the offset voltage introduced into the signal path by the P6230 450 ohm active probe In order to minimize circuit loading it is desirable to set the probe offset bias near the logic zero level or the termination voltage of the ECL circuit being probed To acquire the PROBE OFFSET THRESH must be selected and the channel 1 through 4 to which the P6230 is connected must be selected When the PROBE OFFSET pushbutton is pressed it will light red and the SWITCHING THRESHOLD VOLTS display becomes a DVM that reads the amount of probe offset To measure and acquire the probe offset voltage touch the probe tip to the front panel jack labeled TIP then set the offset adjustment on the probe case to the voltage desired While still holding the probe tip to the TIP jack push the PROBE OFFSET button once again to acquire this offset measurement into t
93. l components Section 4 CHECKS AND ADJUSTMENT contains procedures to check the operational performance and electrical characteristics of the instrument Procedures also include methods for adjustment of the instrument to meet specifications Section 5 INSTRUMENT OPTIONS contains a description of available options Section 6 REPLACEABLE ELECTRICAL PARTS contains information necessary to order replaceable parts and assemblies related to the electrical functions of the instrument Section 7 DIAGRAMS AND CIRCUIT BOARD ILLUSTRATIONS includes detailed circuit schematics locations of assembled boards within the instrument voltage and waveform information and circuit board component locators Section 8 REPLACEABLE MECHANICAL PARTS includes information necessary to order replaceable mechanical parts and shows exploded drawings which identify assemblies Volume 2 of the service manual contains signature analysis tables to be used with the diagnostic information provided in the Maintenance section of the Volume 1 service manual INSTALLATION INITIAL INSPECTION This instrument was inspected both mechanically and electrically before shipment It should be free of mars or scratches and should meet or exceed all electrical specifications To confirm this inspect the instrument for physical damage incurred in transit and check the basic instrument functions by performing the Get Acquainted Exercises in Section 2 Operating Instruction
94. mum set up time Aand B from event A to event B to insure that trigger output occurs with event B Time From 5 ns minimum Minimum time after B to A event B to next event A to insure proper arming Event Duration Minimum time to insure proper arming and triggering Event A 5 ns minimum Event B 5 ns minimum Front Panel The front panel A A THEN B THEN B Gate Output Gate Output is active only if sel ected and in the A THEN B mode refer qualified service personnel to 7A42 Service Manual for selection Voltage Logic Zero lt 0 2 V into 50 ohm load Logic One 20 8 V into 50 ohm load Output Impedance Approximately 50 ohms m m m gm m m qon m m m m m Ej Ej f IF gp On 4 amc a cL a a General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Characteristic Performance Supplemental Requirement Information TRIGGER CONT TRIGGER OUT Connector cont A THEN B GATE TRIGGER OUT cont Timing Time from Event A Recognition to Rising Edge of Gate 25 ns or less Mainframe A THEN B Gate Output Amplitude 1 MHz Square Wave Active only in A THEN B Mode 300 mV 50 mV p p differential into A13 and B13 of main inter face connector on right side of plug in Centering 1 MHz Square Wave
95. ndicators and therefore the function that will produce the trigger output The other function is stored in memory and may be called up by pressing that pushbutton The programming or clearing of the function displayed will not affect the other function A THEN B NESTED TRIGGERING One level of nested triggering is available when this mode is used The trigger output to the mainframe time base occurs only after the triggering is first armed by the occurrence of function A The trigger output then takes place with the next occurrence of function B After this cycle the 7A42 will begin to look for another occurrence of function A to begin the next nested trigger cycle 2 60 in ia m 4 n El Hy Wi gy Ng H H te Operating Instructions 7A42 TRIG VIEW The TRIG VIEW trace provides a visible replica of the trigger output signal as it is processed by the 7A42 according to the programmed TRIGGER FUNCTION This trigger signal is also sent to the time base When the EXT CLOCK SYNC pushbutton switch is lit the TRIG VIEW trace displays the external clock input signal The TRIG VIEW trace is normally located near the bottom of the crt display There is an internal provision for repositioning the trace to reposition the TRIG VIEW trace refer qualified service personnel to the 7A42 Service Manual If all of the channel displays are turned off the TRIG VIEW trace will be on and cannot be turned off TRIGGER
96. ned in black and white at 600 dpi unless the original manual had colored high lighting as is the case for some 70 s vintage Tektronix manuals 4 Most manuals are text searchable 5 All manuals are fully bookmarked All data is guaranteed for life yours or mine which ever is shorter If for ANY REASON your file becomes corrupted deleted or lost Artek Media will replace the file for the price of shipping or free via FTP download Thanks Dave amp Lynn Henderson Artek Media UU dal UNT Un i LU 7A42 Operators TABLE OF CONTENTS B uas UR ux iU d E J ui iE em Page OPERATORS SAFETY SUMMARY vi DESCRIPTION xo re lett oleae Gea dee E viii GENERAL INFORMATION COLOR USED IN THIS 1 1 TECHNICAL MANUALS 1 1 OPERATORS MANUAL 1 1 SERVICE MANUAL 1 1 INSTALLATION ir rer yee Sects Masada eee enel 1 2 INITIAL 1 5 nn 1 2 OPERATING TEMPERATURE 1 3 INSTALLING THE 7A42 IN THE MAINFRAME 1 3 MAINFRAME COMPATIBILITY 1 4 PACKAGING FOR 1 5 SPECIFICATION 2 hr hh ATI bones deus 1 6 STA
97. nel display with an external clock signal displayed on the TRIG VIEW trace esit per X e gt UTERE au EE 3 3 Triggering on low amplitude 3 5 Timing diagram of a typical microprocessor read cycle 3 6 Set up to monitor invalid data 3 8 The 7A42 captures a positive transition of data during the time data should be Stable ey rt rd dae uer ind tack 3 8 Bus contention measurement set up 3 10 Standard 500 ohm probe forms voltage divider with termination resistor in ada apte anu Y Santer ea SOR ERE erp INI S 3 14 Simplified diagram of the P6230 Variable Bias Offset probe 3 15 Two ECL level waveforms A without bias offset B with a 2 volt bias offsets cuo ete eee e e ITIN OE E ue pibe 3 16 iwi fa oat wea 3 wm iW WwW wa Wh wa em ini imi imi im RI vete 9 fW A Tou ee e ee ou T m D 7442 Operators LIST OF TABLES Page Shipping Carton Test 1 5 Electrical Characteristics ee eee nee 1 6 Environmental Characteristics III 1 21 Physical Characteristics lisse eee tener eee 1 22 7A42 Self Test Failure
98. nframe crt readout refer to CRT Readout in this section Three sensitivities are available in each logic family see Table 2 4 To increase the sensitivity display size press the upper button TABLE 2 4 Channel Volts Division Ranges Logic Family At The BNC Through a 10X Probe TTL CMOS 2 5 V Div 1 2 5 V Div ECL 20 50 100 mV Div 2 5 1 V Div GND The GND pushbutton connects the selected channel amplifier input to ground as a reference for trace positioning However the incoming signal is not grounded it is disconnected from the amplifier input 1MQ 50Q The 1 0 500 pushbutton selects the input impedance of the selected channel The available impedances are 1 megohm in parallel with about 15 pF or 50 ohms THRESH Each of the four input channels have two possible preset threshold voltages 1 4 volts for the TTL mode and 1 30 volts for the ECL mode In addition these threshold voltages can be altered using the LEVEL or LEVELS pushbuttons The SWITCHING THRESHOLD VOLTS display will indicate the threshold voltage present at each of the channel inputs To turn the SWITCHING THRESHOLD VOLTS display on press the THRESH pushbutton the light should be on The SWITCHING THRESHOLD VOLTS display corresponds to the channel pushbutton that is lit CH1 CH2 CH3 or CH4 While the button is lit the actual threshold voltage for the channel is indicated in the seven segment LED display For each logic fam
99. ng the 7A42 s A THEN B Gate signal to gate the counting and timing system in the 7D15 allows a variety of difficult measurements The 7D15 can measure the width of the 7A42 s A THEN B Gate to determine how much time elapsed between Trigger Function A and Trigger Function B The 7D15 will also function as a gated events counter capable of counting the number of cycles between Trigger Function A and Trigger Function B or as an events counter to provide a total count of trigger events over an extended period of time e g reliability testing UU 4 ut i EVENTS COUNTING No matter what mode of operation the 7A42 is in the 7D15 can count the number of triggers generated by the 7A42 over a predefined period No external connections are necessary to accomplish this With the 7A42 occupying the two leftmost compartments and the 7D15 occupying the horizontal A compartment 7A42 trigger signals are sent directly to the counter along the 7000 Series mainframe trigger path To count the number of errors occurring in a digital system make the necessary connections of the data lines to the 7A42 s input E ui T M E e 0 rr RE eum v m C4 channels program the trigger function to recognize the error condition and set 7 the 7D15 as follows Rm 7D15 Settings L o E ERU en ei Mee chile Ks Frequency B R a Storage RS EN IM ELEME RS Off a ethos roo
100. nix 7000 series Oscilloscopes It was specifically designed to display and make measurements on digital logic signals in the TTL ECL and CMOS logic families While the display output from the 7A42 is analog the trigger output is digital and is comprised of a user selectable Boolean function of the four input channels A fifth TRIGGER VIEW trace depicts either the trigger function output or the external clock input viii m m m m m m m m m m m m Im O OWj nw wo m nw Wn Wn e Wn v Hv HW vw Ww v v Hv HW Wn Hn n v dw SECTION 1 CONTENTS COLOR USED IN THIS MANUAL 1 1 TECHNICAL MANUALS en 1 1 OPERATORS 1 1 SERVICE MANUAL sesi otter tis Lager SEE coed eines 1 1 INSTALLATION again Lae aun de aed eae eed 1 2 INITIAL INSPECTION sets occ cence een eens 1 2 OPERATING TEMPERATURE 1 3 INSTALLING THE 7A42 IN THE 1 3 MAINFRAME COMPATIBILITY 1 4 PACKAGING FOR nne 1 5 SPECIFICATION eiii lel bre essed Yet e re 1 6 STANDARD ACCESSORIES 1 24 OPTIONAL ACCESSORIES 1 24 PROBES sakes aR an e
101. njunction with the 7A42 trigger view feature where conventional oscilloscopes would have difficulty displaying an Edge Qualified trigger function at slow speeds 3 18 d mm o pend SECTION FOUR INSTRUMENT OPTIONS No options existed for the 7A42 at the time of this printing Information about any subsequent options will be included in the CHANGE INFORMATION section at the back of this manual Spec ication ua 421 Ls OF 25 Index 7A42 CABLES 2 57 i pies CHARACTERISTICS See E 1 6 EA UE CH1 CH2 CH3 CH4 2 10 1 2 64 2 67 yo oe BS a oe CHOP 2 10 2 60 on CLEAR 2 10 2 67 S CLOCK CYCLES BETWEEN EVENTS 3 12 CODES Error Summary 2 50 2 51 2 52 _ COLOR USED IN THIS MANUAL 1 1 COMPATIBILITY 1 3 COMPENSATION OF PROBES 2 57 CONTROLS CONNECTORS AND INDICATORS Description and Illustration of 2 10 2 11 2 12 CONTROLS Front Panel 2 10 CRT READOUT 2 57 D DEFLECTION FACTOR 2 65 DELIMITER 2 67 DeMORGAN S THEOREM 2 4 25 ex arque DISPLAY 2 10 2 59 2 65 BE E LAT uso Specification of t 6 e DOCUMENTATION RELATED 1 1 DVM 2 6 E 2 10 2 59 EDGE 2 10 2 67 Sensitivity 2 7 3 6 i ERROR CODES 2 50 2 51 2 52 ELECTRICAL CHARACTERISTICS See Specifications
102. ntrols are activated and are used with the CH1 CH2 CH3 and CH4 pushbutton controls to program a Boolean equation into the A TRIGGER FUNCTION or B TRIGGER FUNCTION The following text discusses first the PROG CHAN controls and then the PROG TRIG controls PROGRAM CHANNEL MODE The TTL ECL VOLTS DIV GND 1MQ 50Q and DISPLAY controls are active in the PROG CHAN mode These controls are used with the CH1 CH2 CH3 and CH4 pushbuttons to set the status of each channel 2 64 iT FT MA pA F nj my T T3 5 Tt FI IH FI gg CT UJ I dU am Ea 6 u u Operating Instructions 7A42 CH1 CH2 CH3 CH4 In the PROG CHAN mode the CH1 CH2 CH3 and CH4 pushbuttons are used to select and indicate the channel which will respond to the TTL ECL VOLTS DIV GND 1MQ 50Q DISPLAY and THRESH pushbutton controls DISPLAY The DISPLAY pushbutton turns the selected channel display on or off In the off position the trace is removed from the crt display However the signal applied to that channel is still routed to the TRIGGER FUNCTION circuitry providing the channel GND indicator is not lit TTL ECL The TTL ECL pushbutton offers a threshold range and selection of display sensitivities appropriate for either TTL or ECL logic families VOLTS DIV The VOLTS DIV pushbuttons set the scale factor of the selected channel The scale factor is displayed on the mai
103. onizing triggers to an external clock signal source EXT CLOCK SYNC light must be on EXT CLOCK SYNC Pushbutton switch allows an external clock to qualify the TRIGGER FUNCTION 4 EX Pushbutton switch selects positive going or negative going edge of the external clock signal which qualifies TRIGGER FUNCTION A B A THEN B Two independent TRIGGER FUNCTION programs are available A and B The A THEN B is a nested combination where A must occur to arm triggering before B is allowed to produce a trigger output RESET External input to disable the TRIGGER FUNCTION output and disarm the A THEN B nested triggering no arming or triggering can occur while a high level is applied TRIGGER FUNCTION LED display indicates the Boolean function which will produce a TRIGGER FUNCTION output Number 6 7 and 10 controls are used to program TRIGGER FUNCTION lights SWITCHING THRESHOLD VOLTS LED display indicates threshold voltage of the channel selected by controls listed under number 6 or displays probe offset LEVEL Two pushbutton switches set threshold voltage of channel selected by the controls listed under number 6 PROBE OFFSET Measures offset voltage of probe connected to the channel selected by controls listed under number 6 PROG CHAN TRIG must be set to CHAN PROG CHAN TRIG must be set to TRIG PROG CHAN TRIG must be set to CHAN and THRESH must be active 2 12 AI C gd Fj
104. onnect clock signal from the unit under test to the 7D15 B input e a ERN ERR TRES i BS eS CH A Gate MOdG DUREE peream UN a hale HE Freq B Display Tithe S roe Ee RR ER Ire vs 0 1 sec o ee betta eno RN SA dto Off Trigger A SOU CO iz ea ae et shed ase d e a eA Reg s Trigger Source icai ain eden Co pling ice va UM D Ite E EL Ub TESTO E DC Level tet Cp sedet Es ote Cad be eR d Preset Trigger B SOUTER Mate ahs Mok ea quede Input B oet eue As needed clock polarity Coupling y ee ie eect dg lated e Se a IPTE As needed Level csse eebubev reso x ARE As needed clock threshold Sensitivity iilius ERR REA CES edge As needed Mainframe Settings Set the Trigger Source for the compartment containing the 7D15 to Right Vertical MEASURING TIME FROM FUNCTION A TO FUNCTION B The 7D15 s accurate internal clock can be used to determine the elapsed time from recognition of Function A to recognition of Function B The width of the 7 42 5 A THEN B gate out represents this time and can be measured by the 7D15 with no external connections The 7D15 will receive this gate from the mainframe s trigger path measure its width and display the results of the measurement on the crt readout For further information refer to Mainframe A THEN 8 Gate Out Pulse Width in section 1 of this manual under specif
105. onship of the TRIGGER OUT waveform to the input signals INPUT SIGNALS TRIGGER OUT CONNECTOR 4285 211 Figure 2 16 Timing diagram depecting the TRIGGER OUT wavelorm as a result of the TRIGGER FUNCTION reacting to the input signals Two modes of operation can be selected for the TRIGGER Out connector Normal and A THEN B Gate In Normal Mode the A THEN B Trigger Out is a pulse regardless of the duration of Trigger Function B A typical timing diagram depicting the Normal and A THEN B Gate modes is shown in Figure 2 17 For selection of either mode refer qualified service personnel to the 7A42 Service Manual The TRIGGER OUT signal levels are compatible with the RESET input levels 2 63 Operating Instructions 7A42 fa CH1 AND CH2 Jb CH2 AND NOT EDGE CH3 INPUT SIGNALS TRIGGER TRIGGER OUT CONNECTOR A THEN B lI NORMAL 4285 212 Figure 2 17 Example of A THEN B level and EDGE sensitive TRIGGER FUNCTION showing the Normal and A THEN B Gate waveform alternatives PROG CHAN TRIG The PROG CHAN TRIG pushbutton selects one of two modes PROG CHAN program channel or PROG TRIG program trigger In the PROG CHAN mode the DISPLAY VOLTS DIV GND 1 500 TTL ECL and THRESH pushbuttons are activated These controls are used with the CH1 CH2 CH3 and CH4 pushbuttons to individually set the channel status In the PROG TRIG mode CLEAR AND OR NOT and EDGE pushbutton co
106. onvenient CHA EXT 70 EXT Avoid use of second CLOCK CLOCK external clock column Repair when convenient FRONT PANEL INITIALIZATION While getting acquainted with the 7A42 it might be desirable to begin operation with the front panel controls set to a known state initialized The front panel will initialize to the control settings listed in Table 2 2 and as shown in Figure 2 12 To initialize the 7A42 front panel control settings see Exercise 1 in the Get Acquainted Exercises of this section BATTERY BACKUP Upon completion of the self test sequence the 7A42 battery backup feature restores the 7A42 front panel control settings to the same settings that were present when the power was turned off 2 52 Ti FA g Ha 1 3 44 za B Ux lM m UNS 1 iM iM 1 B ud Ll xa al edd a lal plicata ee e im r ry Operating Instructions 7A42 TABLE 2 2 7A42 Front Panel Control Settings When Initialized Control Control Setting PROG CHAN TRIG Programmable Channel Program Channel light off CH1 only DISPLAY CH1 only VOLTS DIV CH1 through CH4 Preset to 0 5 V Div at bnc input TTL ECL CHT through TTL GND CH1 through CH4 Ungrounded 1MQ 50Q CH1 through CH4 1MQ ALT CHOP ALT TRIG VIEW Off
107. oo low to be recognized as a TTL high level and too high to be recognized as a TTL low level see Figure 3 4 To locate and trigger on a TTL low amplitude pulse connect the CH1 and CH2 probes to the same point on the signal under test and establish a dual threshold to bracket the suspected amplitude of the pulse as follows 1 Set the CH1 SWITCHING THRESHOLD voltage for 2 0 and the CH2 SWITCHING THRESHOLD readout voltage for 0 8V 2 Enter keystroke sequence NOT CH1 AND CH2 The 7A42 will monitor the data line looking for a pulse which is less than 2 0 CH1 and greater than 0 8V AND CH2 in amplitude The time base should be set to Auto trigger and Slope so that it will trigger on the positive slope of the signal from the dc coupled internal source Because the same signal is present on CH1 and CH2 only one channel need be displayed Even though only one channel is displayed both CH1 and CH2 will contribute to the trigger function Because valid logic signal transitions also cross the voltage window between the CH1 and CH 2 thresholds trigger outputs may occur when the signals pass through this transition region The 7A42 TRIGGER FILTER control can be used to 3 4 NW i ud ul ut ut neges P oh em le el ST 00 00 UC M l Applications 7A42 7000 SERIES OSCILLOSCOPE TIME BASE UNIT
108. or Since all analog channels are sent out the 7A42 s left interface connector it cannot use the full capabilities of a dual beam oscilloscope such as the 7844 R7844 and the 7612D However it has full compatibility with these mainframes in a single beam configuration Since the 7A42 uses the mainframe crt readout to display the channel volts per division and error warning messages the 7A42 is not recommended for use in mainframes without readout If the 7A42 is used with two time base units in a four compartment mainframe where Chop has been selected as the Horizontal Mode and if exactly four traces are to be displayed by the 7A42 two of the traces may synchronize to one time base while the other two traces synchronize to the other time base To prevent this from happening one trace should be removed or a fifth trace should be added to the mainframe crt display even if it is positioned off screen so it cannot be seen With one two three or five traces the channel display will not synchronize to the horizontal chop frequency The 7A42 is compatible with the 7854 Oscilloscope mainframe when the 7854 is operated in real time However when the 7854 is operated in digital storage and waveform and readout acquisition is desired the 7A42 7854 mode should be selected via an internal jumper refer qualified service personnel to the 7A42 Service manual Once the 7A42 7854 mode has been selected proper readout and waveform acquisition c
109. panel of the mainframe To remove the 7A42 from its host mainframe pull the release latch see Fig 1 1 to disengage the unit from the mainframe then pull the 7A42 straight out from the plug in compartment leaving the mainframe on the bench Figure 1 1 7A42 release latch 1 3 General Information 7A42 MAINFRAME COMPATIBILITY The 7A42 is compatible with all Tektronix 7000 series mainframes In four wide plug in compartment mainframes it can be installed in either the two leftmost or two centermost plug in compartments When used in the two leftmost compartments select the Left Vertical Mode to display the analog signals The associated time base plug in Trigger Source should be Left Vertical with the time base trigger controls set to Auto or Norm Internal Slope to with the Level control centered The A Then B Gate Output can be picked off from the RIGHT VERTICAL TRIGGER SOURCE by a 7D11 or 7D15 from either horizontal compartment In three wide plug in compartment mainframes the 7A42 must be used in the two leftmost compartments in a similar way When the 7A42 is installed in the center two plug in compartments of a four compartment mainframe set the mainframe Vertical Mode and Trigger Source to Right Vertical The maintrame A Then B Gate Output can not be used in this configuration however the A Then B Gate is still available at the front panel TRIGGER OUT bnc connect
110. r Function A with the TRIGGER FILTER control turned off fully counterclockwise Note the pulse width of the Read strobe Now turn the TRIGGER FILTER control clockwise until the width of the Read strobe is shortened by 200 nanoseconds The triggering is now at that point of the Read cycle after which the Data lines must remain stable The TRIGGER FILTER contro will operate only on Function A because Function B will contain an edge sensitive channel The Trigger Filter responds only to level sensitive Trigger Functions The 7D11 is used in the delay by time mode It begins counting when Function A is recognized and times out shortly after the end of the Read strobe A positive transition on the 7A42 s A THEN B Gate out will start the 7D11 s count The 7D11 receives this gate signal internally through the 7000 series main interface At the end of its programmed time interval the 7D11 resets the 7A42 This enables the 7A42 to prepare for the next event even if Trigger Function B is never recognized 3 7 Applications 7A42 7000 SERIES OSCILLOSCOPE READ 7 42 7011 7B10 DLY D 2 RESET TRIG DATA OCH3 OCH4 7A42 TRIGGER FUNCTION Iu e Dea qu ds dl E Re oe FO s NOT CH1 Boss NOT CH1 AND EDGE CH2 OR NOT CH1 AND NOT EDGE CH2 etsi PS yer tees 200 nS OSCILLOSCOPE VERTICAL MODE asd ien tithes CHI e KORR HAS LEFT HORIZONTAL MODE e
111. race SLOPE SELECT Either the rising or falling edge of an external clock signal can be used to qualify the TRIGGER FUNCTION When the Slope Select pushbutton is lit the TRIGGER FUNCTION is qualified on the rising transition of the external clock signal 2 61 Operating Instructions 7A42 EXT CLOCK INPUT The EXT CLOCK INPUT is directly compatible with either TTL or ECL logic families The instrument is shipped from the factory in the TTL mode To determine which mode is selected ECL or TTL proceed as follows 1 Remove any input signal from the EXT CLOCK INPUT 2 Press the PROG pushbutton so that it is lit green 3 Press the CLEAR pushbutton to eliminate any existing TRIGGER FUNCTION 4 Press the TRIG VIEW pushbutton so that the pushbutton light is on and the trigger view trace is displayed on the mainframe crt 5 Observe the trigger view trace as the EXT CLOCK SYNC pushbutton is pressed If the trigger view trace moves upward approximately half a division when the EXT CLOCK SYNC push button is lit the selected mode is TTL If the trigger View trace does not shift the mode is ECL To select the ECL mode refer qualified Service personnel to the 7A42 Service Manual The EXT CLOCK INPUT can be used with a 1X probe in TTL mode or can be directly connected to the logic circuit in either TTL or ECL mode 10X probes should not be used with this input RESET INPUT The RESET INPUT allows the operator to apply a signal
112. red for the channel The SWITCHING THRESHOLD VOLTS display indicates the preset threshold voltage or the variable threshold voltage set by the LEVEL and LEVEL controls The CH1 CH2 CH3 and CH4 pushbuttons indicate which channel s threshold voltage is being monitored When using the P6230 remember the first step is to acquire the probe offset value into the 7A42 Next set the Switching Threshold Voltage with the LEVEL buttons to 2 66 REV JUL 1984 tf AP I 1 Ei ww In R r3 PE I FI f 4 am am m dm adm GE 1 1 1 I L i Operating Instructions 7A42 a value appropriate for the logic family under test The Switching Threshold Voltage at the probe tip is indicated in the numerical display PROGRAM TRIGGER MODE The CH1 CH2 CH3 CH4 CLEAR AND OR NOT and EDGE pushbuttons are active in the PROG TRIG mode These controls are explained next CH1 CH2 CH3 and The CH1 CH2 CH3 and CH4 pushbutton switches are used with the AND OR and NOT pushbuttons to program the TRIGGER FUNCTION e g keystroke sequence CH1 AND CH2 AND CH3 OR CH4 AND The AND pushbutton enters the logical AND operator into the Boolean TRIGGER FUNCTION AND serves as a delimiter for the CH1 through CH4 NOT and EDGE pushbuttons OR The OR pushbutton enters the logical OR operator into the Boolean TRIGGER FUNCTI
113. ristics are listed in Table 1 3 and Physical characteristics are listed in Table 1 4 TABLE 1 2 Electrical Characteristics Characteristic Performance Supplemental Requirement Information DISPLAY Deflection Factor Calibrated Range at Input BNC Connector TTL CMOS 0 1 0 2 0 5 V div Family ECL Family 20 50 100 mV div Calibrated Range through a 10X Probe TTL CMOS 1 2 5 V div Family ECL Family 0 2 0 5 1 V div Channel to Channel Within 2 in ECL Gain Match Logic Family 20 mV div 1 Megohm input impedance m dad mom m l UU 10 IM UO UC UO UE usc LE uc US ud Ml USC l bi Characteristic General Information 7A42 TABLE 1 2 CONT Electrical Characteristics Performance Requirement DISPLAY CONT Supplemental Information Deflection Factor cont Gain Ratio Accuracy within the same Channel Within 2 of indi cated deflection factor relative to ECL Logic Family 20 mV div 1 Megohm input impedance GAIN Range Permits adjustment of deflection factor for cali brated operation with any calibrated 7000 series mainframe Adjustable at least 4 to 4 from c
114. s Qualified service personnel can verify Performance Requirements by referring to the Checks and Adjustment section of the service manual If there is damage or deficiency contact your local Tektronix Field Office or representative 1 2 m m m m m m n m m m m m m m m m m UC UC UN LI REM REN R EROR RO EROR EURO REN RN l al General Information 7A42 OPERATING TEMPERATURE The 7A42 can be operated where the ambient air temperature is from Q to 50 C and can be stored in ambient temperatures from 55 to 75 C After storage at temperatures outside the operating limits allow the chassis temperature to reach operating limits before applying power INSTALLING THE 7A42 IN THE MAINFRAME The 7A42 is designed to operate in the two center or the two left most plug in compartments of a Tektronix 7000 series oscilloscope mainframe NOTE Switch off the mainframe power before installing or removing the 7A42 To install the 7A42 in the mainframe align the grooves in the top and bottom of the instrument with the guides at the top and bottom of the plug in compartment Then push the 7A42 in until its front panel is flush with the front
115. se The Trigger Comparator compares the signal from the Attenuator with the voltage of the Trigger Threshold Generator When the signal from the Attenuator exceeds the Threshold Voltage the Trigger Comparator produces an output which is applied to the Trigger Logic stage The Trigger Logic stage accepts logic levels from the Comparator and compares them with the programmed logic level of each channel When the applied input signal s conform to the programmed trigger logic conditions a trigger pulse is produced The Trigger Logic conditions are user programmed from the front panel 2 1 Operating Instructions 7A42 ATTENUATORS TRIGGER THRESHOLD GENERATORS AMPLIFIERS TO MAINFRAME DISPLAY CRT CHANNEL SWITCHING ALT CHOP TRIGGER VIEW SIGNAL TRIGGER COMPARATORS TO MAINFRAME TIME BASE TRIGGER LOGIC Figure 2 1 Simplified block diagram of the 7A42 2 2 i iu I 14 i ee NT 4 i bal Operating Instructions 7A42 BOOLEAN ALGEBRA FOR 7A42 USE The basis of digital electronics is the binary number system ones and zeroes highs and lows The most common digital circuit components inverters and gates operate on the principles of Boolean algebra Boolean algebra is a binary algebra with many characteristics simil
116. sses iisa i eben EIER Saou a gd deae B A TRIGGER SOURGE exeo bar aaa ed oa RIGHT B TRIGGER SOURCE 4 ers ute pi de bun ARES End LEFT 7D11 BDELAY MODE sd ASE DSA INDEPENDENT COUNTERIMODE ges ees ees aS a er LOUK Res TIME TRIGGER SLOPE hoy Ege ae AEA TaN COUPLING Es LE tee AERA DC SOURCE A SEES ine eA A INTERNAL TIME DELAY SA e ROS VES EES eA sed bete epe s 200 nS 7B10 TRIGGER MODE s oe vl ge e eva va PE ds TRG IH b PS NORM COUPLINGS doa caue sine EACH Ey ie ub Eater se Pa Le Rb DC SOURCE 45 Us de oce ess Ye a ble xat ei rao INT SLOPE doit rt oit Se etit RPA E LAE oisi a 4285 307 Figure 3 6 Set up to monitor invalid data transitions Figure 3 7 The 7A42 captures a positive transition of data during the time data should be stable 3 8 I mU T FH i di WA Nl ul EL UL iL eibi dk fn Mn ndo EN Applications 7A42 APPLICATION 4 DETECTING AND DISPLAYING BUS CONTENTION In bus oriented systems one problem which is difficult to detect with either an oscilloscope or a logic analyzer is that of bus contention Bus contention arises when more than one component attempts to drive a common bus at the same time Consider the simple circuit shown below Three state bus drivers both connect to the same line of a data bus If
117. st press PROG TRIG 5 AND OR REQ While programming a trigger function a CH1 CH2 CH3 CH4 NOT or EDGE was pressed when an AND or an OR key was expected 6 CH KEY REQ While programming a trigger function two Boolean operator keys AND or OR were pressed without pressing a channel key CH1 CH2 CH3 in between Channel keys and Boolean operator keys should be pressed alternately e g CH1 AND NOT CH2 OR CH3 EDGE OR IS FULL The OR key was pressed again Only one TRIGGER FUNCTION OR is allowed EXTCLK ON The EDGE key was pressed while in the EXT CLOCK SYNC mode The selection of an EDGE sensitive channel and the EXT CLOCK SYNC mode are mutually exclusive If EDGE sensitivity is desired first turn off the EXT CLOCK SYNC mode EXTCLK REQ The EXT CLOCK slope key was pressed when the EXT CLOCK SYNC button was turned oft The EXT CLOCK SYNC slope key is operational only when the EXT CLOCK SYNC button is turned on 10 EDGE IS ON The EXT CLOCK SYNC key was pressed when one of the trigger functions either A B or both already have an EDGE sensitive channe Channel EDGE sensitivity and EXT CLOCK are mutually exclusive If EXT CLOCK SYNC operation is desired first CLEAR the channel EDGE sensitive trigger function 2 55 Operating Instructions 7A42 TABLE 2 3 CONT 7A42 Operator Message Summary Code Mnemonic Description and Corrective Action T 11 T
118. ted under ins SYNC sD number 6 DisPLAY Q POSITION OFF gt 300 5 D CH3 O g E EXT CLOG INPUT 3 ALT CHOP Pushbutton switch determines whether the displayed Bap Ll channel s are displayed alternately after each sweep of the time CH4 EDGE base or are displayed simultaneously in a chopped mode soo iwQ 15pt TRIG VIEW Pushbutton to display TRIGGER FUNCTION output signal or EXT CLOCK signal on crt 3 Tektronix 7A42 10 PROG CHAN TRIG must be set to CHAN Figure 2 7 7A42 controls connectors and indicators 2 10 T Ky I Wi In Ir EJ ch T3 By d d d bu G UJ dj da 1 Uh uU min dal dki dal lal liil i Operating Instructions 7A42 The following controls connectors and indicators are common to CH1 CH2 CH3 and CH4 Input Connector Bnc for signal connection POSITION Vertically positions the incoming signal Clockwise rotation moves displayed trace upward DISPLAY When DISPLAY indicator light is on channel is selected for display ECL TTL When indicator light is on the preset threshold voltage and range of deflection factors are compatible with TTL logic levels when off they are compatible with ECL Logic levels GND When indicator light is on the amplifier
119. test sequence to verify that all segments operate If there are no self test failures the Firmware Version number will then be displayed for a few seconds before the self test is completed Self test failures are indicated by three different methods 1 on the mainframe crt 2 on the 7A42 SWITCHING THRESHOLD display and 3 on the TRIGGER FUNCTION indicators Figure 2 11 illustrates a typical self test failure indicated by the three display methods Displaying the self test failure messages in three different ways increases the chance that the failure message will be displayed even if the failure affects the operation of two of the three display methods The TRIGGER FUNCTION display indicates a self test failure with the color red and self test passed with the color green If a failure occurs the self test sequence will stop REV JUL 1984 2 49 Operating Instructions 7A42 The SWITCHING THRESHOLD VOLTS indicator and mainframe crt readout display indicate a self test failure with a numeric code All of the self test code numbers are listed in Table 2 1 along with the nature of the failure and an explanation of the severity of the failure The severity information is helpful in determining if the 7A42 can still be used for the intended purpose or whether repair is necessary To continue the self test sequence press any of the 7A42 front panel pushbuttons NOTE There should be no connections to the RESET EXT CLOCK and TIP inputs
120. the CLEAR pushbutton 128 Now press the CH4 pushbutton 129 Notice the the CH4 TRIGGER FUNCTION indicator 130 is red HI and that the CH4 square wave display is triggered 131 125 129 126 128 2 34 Hu IL HA HA 174 HY TI 13 I IE f m lal de lm Erg m if J pem p pm anioi eee i Uu d t RI Operating Instructions 7A42 To change the CH4 vertical deflection factor 132 press the PROG pushbutton 133 so that the light is extinguished Press the CH4 pushbutton 134 and then press the upper VOLTS DIV pushbutton 135 once for 0 2V as displayed on the crt readout 132 Check the CH4 display 136 for a waveform 2 divisions in amplitude e Ies 7A42 4285 251 134 2 35 Operating Instructions 7A42 EXERCISE 3 LOGIC TRIGGERING Exercise 3 demonstrates the use of the 7A42 TRIGGER FUNCTION feature using two of the four input channels CH1 and CH4 CH1 and CH4 were arbitrarily selected we could have selected any two of the four input channels T
121. tion of controls connectors and indicators Get Acquainted Exercises provide a basic operating procedure for the first time user followed by a systematic demonstration of all front panel controls A detailed description of all front panel controls is also given in this section Section 3 APPLICATIONS gives examples of how to use the 7A42 to make some difficult measurements Section 4 INSTRUMENT OPTIONS contains a description of available options WARNING The following service instructions are for use by qualified personnel only To avoid personal injury do not perform any service other than that contained in the operating instructions unless you are qualified to do so Refer to Operators Safety Summary and Service Safety Summary prior to performing any service Service Manual 1 1 General Information 7A42 The service manual is divided into 2 volumes Volume 1 contains the following Section 1 GENERAL INFORMATION contains content descriptions of the Operators and Service manuals mainframe and plug in compatibility packaging instructions and instrument specifications Section 2 THEORY OF OPERATION contains basic and general circuit analysis that is useful for servicing the instrument Section 3 MAINTENANCE describes preventive maintenance procedures conventional troubleshooting and diagnostic troubleshooting procedures with detailed instructions for replacing assemblies subassemblies and individua
122. tips hooks IC grabbers and ground leads available The P6230 is an active 450 ohm variable bias offset probe which is an excellent ECL logic probe due to its low capacitances and minimal loading because of the variable bias offset feature The 7A42 s PROBE OFFSET feature is designed to work with the P6230 The P6131 accessories will also fit the P6230 See ECL Probing Techniques in the Application section of this manual Passive probes such as the P6131 require low frequency compensation into the inputs of the 7A42 as with any vertical amplifier The mainframe calibrator provides a signal suitable for making this adjustment For optimum high frequency performance the probe high frequency compensation should also be adjusted directly into the 7A42 inputs See the probe manual for instructions to perform this adjustment 1 24 1 4 aq mj m m m ow m am ar on m aan m m m n eo pim m eee NNN NM NN OM N NM NM N I I 1 T SECTION 2 CONTENTS SIMPLIFIED BLOCK DIAGRAM OF THE 7 42 2 1 BOOLEAN ALGEBRA FOR 7A42 2 3 CONTROLS CONNECTORS AND 2 9 GET ACQUAINTED 2 13 EXERCISE 1 PRELIMINARY SET UP AND INITIALIZATION 2 13 EXERCISE 2 OBTAINING A TRIGG
123. to inhibit the trigger output Applying a positive 0 8 volt level to the RESET input will prevent the programmed TRIGGER FUNCTION from being recognized as true The result is that no trigger output signal will occur until the reset voltage is removed If the A THEN B nested trigger mode is selected TRIGGER FUNCTION A has occurred and TRIGGER FUNCTION B has not occurred the RESET signal will reset function A the armed condition as well as inhibit function B Therefore the RESET input can be used to enhance the A THEN B nested trigger operation by providing an A THEN B unless RESET feature TRIGGER OUT The TRIGGER OUT bnc connector is a trigger output signal source This signal can be used to synchronize other equipment with the 7A42 TRIGGER FUNCTION The output of the TRIGGER FUNCTION is determined by the setting of the A B or A THEN B pushbuttons the programming of the A and B functions and the channel input signals Timing diagrams for a typical set of conditions are shown in Figures 2 15 and 2 16 2 62 fui H A IK im C HM Ww UE 17 my ip E E E OE E uu d dE GE E E dE am d S mmus pL dS A a NY COR ADIRE GI qu a PEN epo cum ny Operating Instructions 7A42 J CH1 AND NOT CH2 AND NOT CH3 INPUT SIGNALS TRIGGER OUT CONNECTOR Figure 2 15 Timing dlagram showing the relati
124. ure 3 11 Two ECL level waveforms A without bias offset B with a 2 volt bias offset 7A42 PROBE OFFSET FEATURE The 7A42 features a built in digital voltmeter which was designed to accommodate the P6230 Variable Bias Offset Probe Pressing the 7A42 s PROBE OFFSET pushbutton while in the program channe mode with the SWITCHING THRESHOLD VOLTS monitor turned on will cause the button to light red This red light indicates that the digital voltmeter is enabled and ready to measure the probe offset Place the tip of the probe into the 7A42 s PROBE TIP jack and set the probe offset to the desired voltage While holding the probe tip in the jack push the PROBE OFFSET button again until it lights green The offset for that particular channel has now been measured acquired and will be compensated for automatically when setting the threshold for that channel In other words the user having acquired the probe offset for a particular channel need not take that offset into account when setting the logic threshold for that channel When using the P6230 remember the first step is to acquire the probe offset value into the 7A42 Next set the Switching Threshold Voltage with the LEVEL buttons to a value appropriate for the logic family under test The Switching Threshold Voltage at the probe tip is indicated in the numerical display 3 16 REV JUL 1984 Ww ppm S Fal F Er i ou ou Applications 7A42
125. y an audible beep When they occur the mainframe readout will display a mnemonic at the top of the crt and a number code at the bottom The mnemonic is an abbreviated explanation of the operating condition which caused the message to be displayed The code number references the message to Table 2 3 which gives a more complete explanation of the operating condition NOTE The audible beep can be turned off refer qualified service personnel to the 7A42 Service Manual Volume 1 2 54 FY gy r wu EF ue 3 B E P H IR ws M X gis E IB UN US uU ue Ub e d dB Ut du ut anoo cula ee ee amid iB impen it ANY Operating Instructions 7A42 TABLE 2 3 7A42 Operator Message Summary Code Mnemonic Description and Corrective Action 1 OVERLOAD A channel input is overloaded Remove the overvoltage and unground the channels to continue operation 2 OFFSET ACQ A key was pressed while Probe Offset acquisition was in progress Push PROBE OFFSET once to lock in acquired value or twice to turn PROBE OFFSET off before continuing operation 3 PUSH PROG Key s pressed is are active only in PROG CHAN mode To use key first press PROG CHAN 4 PUSH PROG Key s pressed is are active only in PROG TRIG mode To use key fir

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