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1141A Differential Probe and 1142A Probe Control

1. 13 H mg m 233 cte R62 R63 H R57 224 galt zes BE 04 R52 R37 us u2 R26 eo 2 60 R35 2 T ice 3 IS G 5 06 8 Cl er un L 03 4 221 R25 A m E es iet NI BB 9 cz ml S 5 5 1 81 F R48 2 R45 R39 HS1 5 51 2 lt To R8 gg E
2. MET POLY 28480 10160 5469 C21 22 NOT ASSIGNED C23 0180 3784 4 CAPACITOR FXD 22UF 20 25VDC TA 28480 10180 3784 C24 0180 3784 CAPACITOR FXD 22UF 20 25VDC TA 28480 10180 3784 C25 0180 3784 CAPACITOR FXD 22UF 20 25VDC TA 28480 10180 3784 C26 0180 3784 CAPACITOR FXD 22UF 20 25VDC TA 28480 10180 3784 80 Service Replaceable Parts Power Supply Replaceable Parts Ref Des Part Oty Description Number Code Number NOT ASSIGNED CR2 1901 1087 2 DIODE PWR 100V 04713 501 CR3 1901 1087 DIODE PWR RECT 100V 3A 04713 501 CR4 NOT ASSIGNED 5 1901 0731 8 DIODE PWR 400V 1A 28480 1901 0731 CR6 1901 0731 8 DIODE PWR RECT 400V 28480 1901 0731 CR7 8 NOT ASSIGNED CR9 1901 0731 8 DIODE PWR RECT 400V 28480 1901 0731 CR10 1901 0731 8 DIODE PWR 400V 28480 1901 0731 CR11 1901 0731 8 DIODE PWR 400V 1A 28480 1901 0731 CR12 1901 0731 8 DIODE PWR 400V 1A 28480 1901 0731 CR13 1901 0734 2 DIODE PWR 1N5818 30V 04713 5818 CR14 1901 0734 2 DIODE PWR 1N5818 30V 04713 5818 CR15 16 NOT ASSIGNED CR17 1901 0731 DIODE PWR RECT 400V 1A 28480 1901 0731 CR18 1901 0731 DIODE PWR RECT 400V 1A 28480 1901 0731 051 1990 0521 1 LED LAMP LUM INT 2 2MCD IF 50MA MAX 24840 5082 4955 E1 2110 0642 1 F
3. black B Hd MP1 DS1 MP2 MP3 HIDDEN 53 52 01143C01 Power and Control Board Component Locator 74 Figure 3 13 Service Replaceable Parts PROBE OUTPUT gt T 1 lt gt P2 1 1 t 6 36V 1 2 LFSIGNAL 1 3 1 ji 1 1 1 1 5 5 gt 5 1 WP OFFSET 4 7 2 e SHIELD gt gt 4 5V 4 9 4 6V 4 1 10 gt 8 n indes 54715A PLUG IN PROBE POWER ASSEMBLY Pa CABLE CONNECTORS P3 1 9 1 LFSIGNAL 1 1 OFFSET 2 2 ot 6 3 3 2 40 NC 415V 4 4 PROBE 5 5 KEY 1 gt INTERFACE 6 6 Ly 6V t P3 gt 777 NO dei id 01141804 Cabling Diagram 75 Figure 3 14 Service Replaceable Parts 1 1 1 1 1 see 5 1 LT1012 0 1 2 3 OFST 6 OFFSET 11 2 EY lt 2 9 1 2 8 OFFCOM
4. MISC O1161E15 Disassembling Adapters With the thumb and forefinger squeeze the tabs together as indicated by the arrows Simultaneously push the tabs into the outer housing so the inner housing begins to slide out While holding the outer housing push back against the thumbwheel until the inner housing can be grasped and removed Reassemble Adapter Reassembling the adapter is slightly harder because you have to align the connector pins and thumbwheel screw while sliding the inner housing and outer housing together Be sure the input connectors and output pins are present and seated on the substrate or PC board 68 Service Removing and Replacing Assemblies 2 Combine the thumbwheel screw and thumbwheel and insert them into the hole in the outer housing 3 Insert the substrate board into the outer housing Slip the attenuator ground attenuator adapters only over the thumbwheel screw and seat the input connectors in the proper holes in the housing Figure 3 10 Reassembling the Adapter Do not force reassembly of the adapter The housing halves will slide together with moderate friction 4 Align the inner housing tabs with the grooves in the side of the outer housing and slide the two partly together While seating the thumbwheel screw and pins it will help to hold the assembly vertically with the input end of the adapter down This will allow the assemblies to sit vertically and more easily ali
5. Power Supply Replaceable Parts Ref Des Part Oty Description Mfr Mfr Part Number Code Number Prefix the reference designators with C1 0160 6190 2 CAPACITOR FXD 0 33UF 10 28480 0160 6190 C2 0160 5474 1 CAPACITOR FXD 0 1UF 5 MET POLY 28480 10160 5474 C3 0180 3298 2 CAPACITOR FXD 2200UF 30 10 AL 28480 0180 3298 C4 0180 3298 CAPACITOR FXD 2200UF 30 10 AL 28480 0180 3298 C5 0160 6500 4 CAPACITOR FXD 0 01UF 10 100VDC CER 28480 0160 6500 C6 0160 6500 CAPACITOR FXD 0 01UF 10 100VDC CER 28480 0160 6500 C7 0160 6500 CAPACITOR FXD 0 01UF 10 100VDC CER 28480 0160 6500 C8 0160 6500 CAPACITOR FXD 0 01UF 10 100VDC CER 28480 0160 6500 C9 0180 3845 4 CAPACITOR FXD 4 7UF 10 35VDC TA 28480 0180 3845 C10 0180 3845 CAPACITOR FXD 4 7UF 10 35VDC TA 28480 0180 3845 C11 NOT ASSIGNED C12 0160 5581 1 0 033UF 10 63VDC 28480 0160 5581 C13 0160 6190 CAPACITOR FXD 0 33UF 10 50VDC 28480 0160 6190 C14 0160 7060 1 CAPACITOR FXD 3 3UF 10 63VDC 28480 0160 7060 C15 0160 4801 1 CAPACITOR FXD 100PF 5 100VDC CER 28480 0160 4801 C16 0180 3845 CAPACITOR FXD 4 7UF 10 35VDC TA 28480 0180 3845 C17 0180 3845 CAPACITOR FXD 3 3UF 10 63VDC 28480 0180 3845 C18 NOT ASSIGNED C19 0160 5471 1 CAPACITOR FXD 0 1UF 5 MET POLY 28480 10160 5471 C20 0160 5469 1 CAPACITOR FXD 10
6. R21 R22 14 c13 41 Fim 1 7 Sur TO 448 15V lt 6 Ree REA R26 15 172 4 S C21 J 01UF 2 C18 A J 6 6 01UF A DC REJECT Lir sow LT1012 VA 1 1 1 1 CR18 A P i 114280H2 IC Connectors not Shown J3 J2 Suppl Pin No IC Grou ete 570797870 15 3 0 uer GND 15 415 7 U6 8 11 9 15 4 NC 1 5 8 5 16 U9 GND 8 1142A Probe Control and Power Module 76 Service Replaceable Parts Figure 3 15 CR10 pa 4 7UF CR12 T eu VP P A 1 CR14 R17 R19 22UF 5000 500 1142A Probe Control and Power Module 77 Service Replaceable Parts 1141A and 1142A Replaceable Parts Ref Part Oty Description Mfr Mfr Part Des Number Code Number 1141A Differential Probe Al 01141 66503 1 PC ASSEMBLY DIFFERENTIAL PROBE 28480 101141 66501 E1 01141 26102 2 PROBING PIN 28480 101141 26102 E2 01141 22301 1 GROUND BLACK 28480 101141 22301 E3 01141 22401 1 GROUND SCREW 28480 101141 22401 101141 24102 2 CAP PROBING PIN 28480 101141 24101 2 01141 44702 1 BOTTOM COVER 28480 101141 44701 01141 44102 1 PROBE COVER 28480 101141 44101 4 01141 22502 1 PROBE POS CLAMP RING 28480 0
7. Calibration Tests and Adjustment dc Gain Accuracy 6 Carefully connect the input of the probe attenuator to the test board in the position shown in the figure below signal to input Pos 9 Signal to input Record the measurement from the bottom DVM in figure 2 2 Calculate the 100x attenuator gain as AV Vout 2 X Vin Record the result of this calculation in the Calibration Test Record on page 39 Failure of the accuracy test for the 100x attenuator can be caused by mis adjustment of the low frequency CMRR LF CMRR adjustment Perform the Attenuator Adapter Adjustment procedure in the Adjustments section later in this chapter then retest the attenuator adapter If if continues to fail repair is necessary 33 w Calibration Tests and Adjustment Bandwidth Bandwidth This test checks the high frequency response of the 1141A Differential Probe The bandwidth of the oscilloscope is characterized first so it is not a factor in the measurement Specification 3dB dc coupled to 200 MHz Equipment Required Equipment Critical Specifications Recommended Required Model Part Oscilloscope 400 MHz bandwidth 54830A Signal Generator 200 MHz at 230 mVrms 8648A Test Board No substitute 01141 66504 Cable Type N m 24 inch 11500B Adapter Type N f to BNC m 1250 0077 Procedure This test depends on the accuracy of the
8. or as close to that as possible Adjust slowly and press CLEAR DISPLAY frequently to restart averaging R13 HF COMP D11u1 7T11u1 03 R13 Adjustment The minimum allowable amplitude is 212 Typical values will be between 275 and 325 mV y the probe needs repair if the minimum cannot be reached Probe Reassembly Disconnect the probe power cable at the rear panel of the 1142A Remove the probe PC assembly from the test board Be sure the probe input connectors remain attached to the probe 3 Remove the grounding screw and ground block from the PC assembly 47 Figure 2 22 CAUTION Calibration Tests and Adjustment Adjustment Procedure Assemble the PC assembly in the top cover The side of the PC assembly with the large hybrid is exposed when the assembly is in the top cover The figure below shows how the top cover PC board and ground block fit together Reassembling Probe Insert the input connectors first and seat the cable end of the PC assembly over the pins at the rear of the cover b Position the ground block at the center front of the PC assembly Insert the grounding screw through the top cover and PC assembly and screw it into the ground block as shown Replace the bottom cover Position the cable strain relief and with one hand hold the cable and top together The flange on the strain relief has a notch that fits around a protrusion in the top cover Note w
9. A power switch is not required because of the low mains power requirement f N WARNING Remote Interface continued protection 1 runeting again re replace Sune oniy with fuse of 2 Dis common 7 same type and ratings 4 External B External Proba offset common offset Line select 6 Shield a 00999 115 230VAC d 47 440 Hz Fuse 25VA Max 2507 250mAT 1142A Rear Panel Procedure Use the power cord to connect the 1142A to the ac mains Connect the 1141A probe cable power connector to the PROBE connector on the rear panel of the 1142A power module Connect the output of the probe to the input of the oscilloscope Set the input impedance of the oscilloscope to 50 If the oscilloscope does not have a selectable 50 Q input impedance connect a 50 0 BNC feedthrough termination between the probe output and the input of the oscilloscope If making an initial equipment setup continue with the initial adjustment in the following section Initial Adjustment Fora given combination of 1141A Differential Probe and 1142A Probe Control and Power Module you may want to adjust the Offset Null and DC Reject Gain Typically you need to make these adjustments only once before the probe is first used You can make them any time to optimize the system These adjustments do not affect the specifications of the probe system 11 Operating the Probe Recommend
10. Grid Ref Grid Des Loc Des Loc Des Loc Des Loc Des Loc Des Loc Des Loc Des Loc C1 C 2 C17 6 10 C 5 6 7 5 6 1822 3 1845 C3 05 0 6 C2 F 3 C18 5 CR11 C 3 2 7 186 6 1823 5 1846 C 3 06 3 C3 H 2 C19 6 12 C 6 1 3 6 7 R7 4 1824 5 1847 05 2 107 C 3 4 3 C20 B 5 CR13 C 3 R8 1825 B 2 1848 0 3 108 B 3 C5 C 3 621 5 CR14 C 6 MP1 H 1 9 4 1826 B 2 09 5 C6 C 5 C22 6 17 5 MP2 1810 C 5 1827 5 3 010 C 2 C7 B 3 C23 4 CR18 B 6 MP3 0 3 811 C 5 1828 5 C3 C8 C 5 C24 B 6 MP4 5 2 5 1829 6 151 H 7 C9 C 5 C25 B 4 051 62 MP7 E 4 1813 R30 6 152 2 5 C26 6 6 MP8 6 4 4 C 4 831 B 3 C11 1 F6 9 6 4 815 C 4 1832 2 H 5 C12 3 CR2 F3 E E 6 R16 0 4 840 C2 C13 3 F3 P1 E7 17 A2 A2 1 D 4 C14 4 5 3 Fl 6 818 66 2 C 2 02 D 5 3 CR6 5 R3 6 419 C6 1843 C2 03 2 C16 4 CR9 3 HS1 0 5 184 6 821 3 844 3 14 D 3 85 Service Replaceable Parts 86 Index Numerics 100x attenuator test 32 10x attenuator test 30 A ac adapter 20 ac coupling adapters 19 ac low frequency 55 accessories available to order 8 circuit connector posts 15 extension leads 14 ground leads 14 mini grabbers 15 probe tips 14 shielded signal leads 15 supplied with probe
11. The strip of circuit connection posts provided as an accessory has 0 025 inch square pins The mini grabber has a 0 25 inch square pin The ground connection at the end of the probe and adapters where the adapters fasten accepts an M3 metric screw Test Board The primary use of the test board is to apply test and calibration signals to the input of the probe or adapters Specific use of the test board is covered wherever it applies Grounding Grounding is very important when probing circuitry Improper grounding can increase the common mode signal level This reduces the effectiveness of the differential probe The mechanical connections at the input of the probe are ground for probe signals The scr ew where the ground lead attaches see figure 1 7 fastens to this ground Also the attenuator and ac adapter fasten to this ground through the screw connection and the ground is carried through each adapter to its front O1141E18 be Grounds Coupling Functions There are three methods for blocking or compensating for the dc component of a signal Each has specific advantages 18 Operating the Probe Probe System Coupling Functions dc offset dc Reject ac Coupling Adapter dc Blocked Probe alone 20V 20V 20V Probe with 10x 200 200 500 Probe with 100x 500 500 500 Set up needed Adjust offset to put Select DC Reject Attach ac Coupling signal on screen low fre
12. To inspect the probe Inspect the shipping container for damage If the shipping container or cushioning material is damaged it should be kept until the contents of the shipment have been checked for completeness and the instrument had been checked mechanically and electrically Accessories supplied with the instrument are listed in see Accessories Supplied on page 6 of this manual If the contents are incomplete if there is mechanical damage or defect or if the instrument does not pass calibration tests notify the nearest Agilent Technologies office If the shipping container is damaged or the cushioning materials show sign of stress notify the carrier as well as the nearest Agilent Technologies office Keep the shipping materials for the carrier s inspection The office will arrange for repair or replacement at Agilent Technologies option without waiting for a claim settlement Using the probe with other instruments The 1141 1142 probe system can be used with other instruments as well as oscilloscopes You can use it with a spectrum analyzer or frequency counter or any instrument with an input that can be terminated with 50 Q If you are going to use the probe system with an instrument other than an oscilloscope you may need to set up the probe with an oscilloscope first This will allow you to select coupling and reject modes and set offset so the output of the probe is compatible with signal requirements of the other in
13. 1 7 Note Operating the Probe Recommended Test Equipment Wm cj 5062 7301 10 600 ES ES 5062 7301 SODV pk 5062 7501 pk 1 Basic Accessory Connections Probe Tips Probe tips fit into the receptacles in the probe and are held in place with probe tip caps If necessary you can solder the probe tips into a circuit or wires can be soldered to the tips If you solder to the probe tips be careful not to melt the plastic probe tip caps Because of the close tolerances between the probe tip caps and probe tips it will be difficult to separate the probe tips and caps once the probe tips have been soldered Ground Leads The circular end of the ground lead fits over the screw on the top side of the probe Extension Leads The extension leads provide a flexible connection between circuitry and the probe To provide a male connection to other circuitry connect the extension lead over the probe tips To provide a female connection remove the probe tip caps and probe tips and connect the extension leads to the probe 14 Note Note N Operating the Probe Recommended T
14. 55 5 schematic probe amp power module 65 76 probe control amp power module 77 service policy 63 setting up probe 10 setup procedure 11 12 shielded signal leads 15 signal level 18 specifications performance 55 summing amp 60 system preparation 10 T temperature 58 test 100x attenuator accuracy 32 10x attenuator accuracy 30 bandwidth 34 calibration 27 CMRR 36 record calibration 39 test board 18 26 62 test equipment 9 26 test procedures calibration 27 test record calibration 27 testing interval 27 theory of operation 59 thermal drift 55 troubleshooting power module 64 probe 64 probe control 64 U using accessories 13 using the probe 9 variable offset 22 vibration 58 Ww weight 58 Notices Agilent Technologies Inc 2000 2004 No part of this manual may be reproduced in any form or by any means including electronic storage and retrieval or translation into a foreign language without prior agreement and written consent from Agilent Technologies Inc as governed by United States and international copyright laws Manual Part Number 01141 97002 July 2004 Print History 01141 97000 June 2000 01141 97001 September 2002 01141 97002 July 2004 Agilent Technologies Inc 1900 Garden of the Gods Road Colorado Springs CO 80907 USA Warranty The material contained in this document is provided as is and is subject to
15. 6 test board 26 using 13 accuracy test attenuator 30 32 adapter combinations 17 adapters 16 attenuator 61 adjustment 11 attenuator adapter 49 initial 13 probe 40 42 altitude 58 amplifiers 23 assemblies removing amp replacing 66 attenuator adapter adjustment 49 adapters 61 B bandwidth specification 55 test 34 blocking 18 block level theory 59 cabling diagram 75 calibration test record 39 tests 27 characteristics environmental 58 general 58 performance 55 probe connectors 18 circuit connector posts 15 cleaning instrument 22 CMRR definition 23 high frequency gain 42 low frequency response 44 specification 55 test 36 common mode rejection ratio 23 compensating dc 18 component locator power amp control board 74 connector characteristics 18 compatibility 18 control module 60 coupling functions 18 D de gain accuracy 28 dc mode 55 offset 19 55 dc reject 19 55 de reject gain 11 differential amplifiers 23 differential input range 55 differential probe disassembly 66 reassembly 67 dimensions 58 direct mail order parts 71 displayed noises displayed 55 E environmental characteristics 58 exchange assemblies 63 extension leads 14 F features 2 frequency high compensation 47 low response 44 function select 22 G gain 42 gain accuracy specification 55 general characteristics 58 grou
16. Accuracy gt Signal to input Ni f Calculate probe gain as Vout V 2 Record result of this calculation in the Calibration Test Record on page 39 To pass this test the probe gain 0 98 to 1 02 Failure of the gain accuracy test can be caused by mis adjustment of the probe Perform the Probe Adjustment procedure in the Adjustments section later in this chapter and retest 10x Attenuator Accuracy Test If the gain test for the probe fails the 10x Attenuator Accuracy Test will fail or the results will be poor Do not continue until the probe passes the gain test Disconnect the probe from the test board and connect the 10x attenuator adapter to the probe Carefully connect the input of the probe attenuator to the test board in the position shown in the figure below signal to input 30 Figure 2 4 Figure 2 5 NOTE 1 Calibration Tests and Adjustment dc Gain Accuracy d Signal to input Set the dc calibrator output 3 V dc Record the Vin measurement from the top DVM in figure 2 2 Record the measurement from the bottom DVM in figure 2 2 Carefully connect the input of the probe attenuator to the test board in the position shown in the figure below signal to input Signal to input Record the meas
17. Adjustment Adjustment Procedure 5 Carefully connect the probe to the test board in position shown in the figure below signal to both inputs L h4 _ Signal to both inputs 6 Change the function generator settings to Sine wave 4kHz 1 0 Vp p 7 Change the oscilloscope settings to Menu Selection Setting TIMEBASE time div 50 us div CHAN 1 sensitivity 2 mV div 8 Adjust BANDWIDTH for minimum signal amplitude on the oscilloscope Again adjust C6 slowly and press CLEAR DISPLAY frequently to restart averaging 46 Figure 2 20 Figure 2 21 Calibration Tests and Adjustment Adjustment Procedure High Frequency Compensation This adjustment sequence continues from the Low Frequency Response and CMRR adjustment However it can be done separately if the probe meets all specifications except bandwidth Adjust R13 for unity gain at 200 MHz Connect the signal generator to the test board and set it for 200 MHz and 300mV 107 Carefully connect the input of the probe to the test board in the position shown in the figure below signal to input lt ali Signal to input J Press AUTOSCALE then measure the peak to peak voltage on channel 1 Press SHIFT blue press V P P then press 1 Adjust R13 HF COMP to make the signal amplitude measurement on the oscilloscope 300 mV
18. GTT 5G The following paragraphs cover system preparation and initial adjustments Power Requirements Use a gt gt U gt U gt The 1141A 1142A probe system specifically the 1142A requires a power source of either 90 to 132 198 to 264 Vac 47 to 440 Hz 25 VA maximum Before connecting power to this instrument be sure the line voltage switch on the rear panel of the instrument is set properly Line Voltage Selection Before applying power verify the setting of the LINE SELECT switch on the rear panel of the 1142A The slide switch can be set to either 115 or 230 V 10 WARNING Figure 1 4 Operating the Probe Recommended Test Equipment Before connecting this instrument the protective earth terminal of the instrument must be connected to the protective conductor of the Mains power cord The Mains plug must be inserted in a socket outlet provided with a protective each contact The protective action must be negated by the use on an extension cord power cable without a protective conductor grounding Grounding one conductor of a two conductor outlet does not provide an instrument ground This instrument is provided with a three wire power cable When connected to an appropriate ac power outlet this cable grounds the instrument cabinet The type of power cable plug shipped with the instrument depends on the country of destination The 1142A Power Control and Power Module does not have a power switch
19. Test Record The result should be 0 707 or greater indicating a probe bandwidth of Z00 MHz or more The bandwidth can be checked at other signal levels Change the signal generator output level and oscilloscope V div range proportionally Failure of the bandwidth test can be caused by mis adjustment of the probe Perform the Probe Adjustment procedure in the Adjustments section later in this chapter 35 Figure 2 9 w Calibration Tests and Adjustment CMRR Test CMRR Test This test checks the CMRR at 1 MHz and 100 MHz Specification 3000 1 at 1 MHz 10 1 at 100 MHz Equipment Required Recommended Equipment Agilent Required Critical Specifications Model Part Oscilloscope 400 MHz bandwidth at 1 mV div 54830B Signal Generator 1 100 MHz at 400 mVrms 8648A Test Board No substitute 01141 66504 Cable Type N m 24 inch 11500B Adapter Type N f to BNC m 1250 0077 Procedure Connect the probe power connector to the PROBE connection on the rear of the 1142A Probe Control and Power Module Set the 1142A front panel switches to Local and Zero offset Connect the probe output to the oscilloscope channel 1 input Connect the input of the probe to the test board in the position shown in the figure below signal to input Signal to input Connect the signal generator to the test board Set the signal generator for 1 MHz at 385 mV 1 36 Figure 2 10 Calibration Tests and Adj
20. major assemblies Never remove or install any assembly with the instrument power ON Component damage can occur Differential Probe Use the following procedure to remove and replace the amplifier PC board in the differential probe ELECTROSTATIC DISCHARGE can damage electronic components Use grounded wrist straps and mats when servicing the probe Handle the differential probe carefully once it has been disassembled If unsupported the weight of the cable can put strain on the PC board Disassemble Probe Remove the probe tip caps and probe tips Loosen the probe clamp ring at the cable end of the probe 1 4 turn counter clockwise and slide it down the cable Remove the bottom cover a At the cable end of the probe separate the covers about one centimeter 1 2 inch b Slide the bottom cover toward the cable end of the probe until the locator pins at the probe input clear the holes Then remove the cover Note the way the cable strain relief is keyed and held at the rear of the top cover Remove the probe top cover The ground screw passes through the top cover and PC board and screws into the ground block a Remove the ground screw on the top of the probe At the cable end the PC board fits over the pins in the top cover b Lift the board off of the pins and slide it in the direction of the cable until the input connectors clear the front of the probe Un solder the two connections where the coaxial output cable connec
21. maximum or minimum on any mail order there 15 a minimum amount for parts ordered through a local Agilent Technologies Sale Office when the orders require billing and invoicing e Prepaid transportation there is a small handling charge for each order e No invoices In order for Agilent Technologies to provide these advantages a check or money order must accompany each order 71 Service Replaceable Parts Mail order forms and specific ordering information are available through your local Agilent Technologies Sales Office Addresses and telephone numbers are located in a separate document shipped with the manuals Manufacturers Codes A list of manufacturers codes is given the table below The codes are given for parts in the parts lists The table gives the manufacturer and address for each code Manufacturers Code List Mfr No Name Address 00000 Any satisfactory supplier 06665 Precision Monolithics Inc Santa Clara CA 95050 24546 Corning Glass Works Bradford Bradford PA 16701 27014 National Semiconductor Corp Palo Alto CA 94304 28480 Agilent Technologies Corporate Hq Palo Alto CA 94304 32997 Bourns Inc Riverside CA 92507 72 Service Replaceable Parts Exploded View Figure 3 11 tial Probe Parts 1141A Differen Service Replaceable Parts Figure 3 12
22. termination on the test board and the termination in the oscilloscope Both should be with 1 With the N cable and N to BNC adapter connect the signal generator to the oscilloscope channel 1 input Set the signal generator for 200 MHz at 0 dBm about 224 mVrms Set the 1142A front panel switches to Local and Zero offset On the oscilloscope press AUTOSCALE then set the following parameters Menu Selection Setting TIMEBASE time div 2 ns div CHAN 1 sensitivity 100 mV div input R 50 Q DC ACQUISITION Sampling Mode Real Time Memory Depth Automatic Sample Rate Automatic Averaging Enabled of avg 32 The signal on screen should be about six divisions amplitude Measure the peak to peak voltage of the channel 1 signal and record the reading Vp p mV 34 Figure 2 8 NOTE Calibration Tests and Adjustment Bandwidth 6 Reconfigure the equipment Disconnect the signal generator cable from the oscilloscope input and connect it to the test board b Connect the output of the differential probe to the channel 1 input of the oscilloscope Carefully connect the input of the probe to the test board in the position shown in the figure below signal to input Signal to input Record Vp p reading on the oscilloscope Vp p 1 mV Divide the reading from step 6 by the reading from step 4 Answer from step 6 _ Answer from step 4 _ Record the result in the Calibration
23. 00 MHz at 1 mV div 54830B Signal Generator 200 MHz at 300 mVrms 8648A Test Board No substitute 01141 66504 Cables 2 500 10503A Adapter Type m to f 1250 0780 Probe Preparation The probe cover must be removed before adjustment Drift due to temperature differences with and without covers is negligible Remove the probe tip caps and probe tips Loosen the probe clamp ring at the cable end of the probe 1 4 turn counter clockwise and slide it down the cable Remove the bottom cover a At the cable end of the probe separate the covers about centimeter 1 2 inch b Slide the bottom cover toward the cable end of the probe until the locator pins at the probe input clear the holes Then remove the cover Note the position of the ground block at the input end of the probe The ground block is held through the PC assembly by the grounding screw on the top of the probe The ground block must be reinstalled on the PC assembly after the top cover is removed Handle the PC assembly by the edges of the PC board Remove the ground connection screw on the top of the probe The ground block will become free At the cable end the PC board fits over pins inside the top cover Lift the board off of the pins in the cover and slide it in the direction of the cable until the input connectors clear the front of the probe 41 Figure 2 13 Calibration Tests and Adjustment Adjustment Procedure As shown
24. 0V 10V Probe with 100x adapter 500 V 2 5 Cleaning Requirements If the instrument requires cleaning 1 Remove power from the instrument 2 Clean the external surfaces of the instrument with a soft cloth dampened with a mixture of mild detergent and water 3 Make sure that the instrument is completely dry before reconnecting it to a power source 22 Operating the Probe Recommended Test Equipment Differential Amplifiers and CMRR The 1141A Differential Probe is a high impedance differential amplifier A characteristic of differential amplifiers is the ability to reject signals that are common to the two inputs The common mode rejection ratio CMRR is the measurement of this ability It is expressed as the ratio between the amplitudes of the common mode and differential signals which product equal outputs For example if common mode signal of 1 and differential signal of 1 mV both produce outputs of 1 mV the CMRR is 1000 1 The ability to reject common mode signals is dependent on the balance designed into the differential amplifier At higher frequencies it becomes harder to balance circuit parasitics and parameters of devices so CMRR degrades as frequency increases Also stray coupling increases with frequency and coupling may vary between the two differential paths The CMRR of the 1141A Differential Probe is specified at the input of the probe and cannot be affected expect by adjustments in the probe How
25. 1141 22501 MP5 01141 94307 1 DIFFERENTIAL PROBE LABEL 28480 01141 94301 w1 01141 61603 1 PROBE CABLE ASSEMBLY 28480 101141 61601 10X Attenuator Adapter 01141 26102 2 PROBING 28480 101141 26102 01141 24102 2 CAP PROBING PIN 28480 01141 24101 100X Attenuator Adapter 01141 26102 2 PROBING PIN 28480 101141 26102 01141 24102 2 CAP PROBING PIN 28480 101141 24101 AC Adapter 01141 26102 2 PROBING PIN 28480 101141 26102 01141 24102 2 CAP PROBING PIN 28480 101141 24101 1142A PROBE CONTROL AND POWER MODULE 78 Service Replaceable Parts 1141A and 1142A Replaceable Parts Ref Part Oty Description Mfr Mfr Part Des Number Code Number 1 01142 66501 1 PC ASSEMBLY POWER AND CONTROL 28480 101142 66501 H1 0515 0374 7 SCREW MACHINE 10mm LG 00000 ORDER BY DESP H2 0515 1031 4 SCREW MACHINE 6mm LG 90 DEG FLH HD 00000 ORDER BY DESP H3 0515 1579 1 SCREW MACHINE M5 18mm LG 00000 ORDER BY DESP 101142 47702 1 BOTTOM CHASSIS 28480 101142 47701 2 01142 44101 1 TOP CHASSIS 28480 101142 44101 01142 24701 2 SPACER HEAT SINK 28480 101142 24701 MP4 1 0370 1097 2 KNOB POINTER 28480 0340 1097 MP5 0403 1012 4 FOOT 28480 0403 0727 MP6 5041 0234 5 28480 5041 0234 W1 8120 1521 1 POWER CORD 18 AWG 3 COND 90 IN LG US 28480 8120 1521 Canada only 79 Service Replaceable Parts
26. 31 2 RESISTOR 2 05K 1 0 125W TC 0 100 24546 4 1 8 0 2052 R8 0699 1203 4 RESISTOR 120 0 1 0 125W TF 0 25 28480 0699 1203 R9 0757 0434 2 RESISTOR 3 65K 1 0 125W TF TC 100 24546 CT4 1 8 TO 3651 F R10 0698 4431 RESISTOR 2 05K 196 0 125W TF TC 0 100 24546 CT4 1 8 TO 2052 F R11 0699 1203 RESISTOR 120 0 1 0 125W TF TC 0 25 28480 0699 1203 R12 0757 0434 RESISTOR 3 65K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 3651 F R13 0757 0420 1 RESISTOR 750 1 0 125W TF TC 0 100 24546 4 1 8 0 751 R14 0698 4002 2 RESISTOR 5K 1 0 125W TC 0 100 24546 CT4 1 8 TO 5001 F R15 0699 1203 RESISTOR 120 0 1 0 125W TF TC 0 25 28480 0699 1203 82 Service Replaceable Parts Power Supply Replaceable Parts Ref Des Part Description Mfr Mfr Part Number Code Number R16 0698 6317 RESISTOR 500 0 1 0 125W TF TC 0 25 28480 0698 6317 R17 0698 4002 RESISTOR 5K 1 0 125W TF TC 0 100 24546 4 1 8 0 5001 R18 0699 1203 RESISTOR 120 0 1 0 125W TC 0 25 28480 0699 1203 R19 0698 6317 RESISTOR 500 0 1 0 125W TF TC 0 25 28480 0698 6317 R20 NOT ASSIGNED R21 0698 8827 RESISTOR 1M 1 0 125W TF TC 0 100 28480 0698 8827 R22 0757 0442 RESISTOR 10K 1 0 125W TF TC 0 100 24546 4 1 8 0 1002 R23 0757 0427 RESISTOR 1 5K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 1501 F R24 0757 0401 RESISTOR 100 1 0 125W TF
27. 4 632 mV y Set the oscilloscope to channel 1 and change the horizontal scale to 5 ns div After the measurement settles averaging is complete note the V P P reading Vp p 1 mV Connect the input of the probe to the test board in the position shown in the figure below signal to both inputs Signal to both input Set channel 1 sensitivity to 10 mV div After the measurement settles averaging is complete not the V P P reading Vp p 2 mV Disconnect the probe amp from the test board and measure channel 1 Calculate the CMRR result as follows CMRR Vioisepp The result in step 21 should be 10 representing a CMRR of 10 1 or more Record the CMRR in the Calibration Test Record 38 Calibration Tests and Adjustment Calibration Test Record Calibration Test Record 1141A 1142A Differential Probe Tested by Serial No Work Order No Recommended Test Interval 1 Year 2000 hours Date Recommended next testing Temperature Test Limits Results dc Gain Accuracy Probe 0 98 mV to 1 02 mV Only 10x 0 096 mV to 0 104 mV 100x 0 0096 mV to 0 0104 mV Bandwidth gt 0 707 at 200 MHz CMRR 1 MHz gt 3000 1 100 MHz gt 10 1 39 CAUTION Calibration Tests and Adjustment Probe Adjustment Adjustments This section provides adjustment procedures for the 1141A Differential P
28. Combinations The figure below shows the allowed adapter and probe connections There are two specific combinations that should not be used Do not attach ac adapter between an attenuator adapter and the probe An attenuator adapter must be terminated by the input resistance of the probe The ac adapter isolates the probe input resistance Do not cascade two attenuator adapters The attenuator adapters are designed to be terminated by the 1 MQ resistance of the probe The input resistance of the attenuator adapter is 9 MQ for the 10x adapter and 10 MQ for the 100x adapter OO 5082 7302 X 500V pk 100 01141E23 Allowed Adapter Connections 17 Figure 1 10 Op erating the Probe Recommended Test Equipment Co nnector Compatibility The following are general connector characteristics for the probe adapters and accessories The female connectors on the probe adapters and other accessories are designed to mate with 0 030 inch round or 0 0250 inch square pins The probe adapter and extension lead pins are 0 030 inch round
29. MRR only because all of the factors mentioned above are frequency dependent The unbalances of capacitance and inductance are more important as frequency increases Therefore good high frequency practice is important when using a high impedance differential probe On the other hand if the differential probe is ac coupled to the circuit under test the ac adapter is being used the CMRR will be degraded below a certain frequency the lower the frequency the worse the CMRR This is because unbalance in the series capacitances of the ac coupler becomes more significant the lower the frequency 23 Operating the Probe Recommended Test Equipment 24 Calibration Tests and Adjustment 25 CAUTION Figure 2 1 Calibration Tests and Adjustment Equipment Required Introduction This chapter is divided into two sections The first section gives calibration tests and the second adjustment procedures for the 1141A Differential Probe and 1142A Probe Control and Power Module Equipment Required A complete list of equipment required for the calibration tests and adjustments is listed in Recommended Test Equipment on page 9 Equipment required for individual procedures is listed at the procedure Any equipment satisfying the critical specifications listed may be substituted for the recommended model The Test Board The test board is a supplied accessory for use during calibration tests and adjustments to connect signals t
30. Module For purposes of the following discussion these will be called the probe and the control module respectively IMPEDANCE U3 HIGH FREQUENCY BIAS tN CONVERTERS AMPLIFIER HYBRID SUPPLY BIAS lt 9 P O gt OUTPUT CABLE m o gt Visors DIFFERENTIAL PROBE 1 AMP 1 BNC A OUTPUT BIAS 1 1 1 SLE LF GAIN BANDWIDTH 1 UB e 2 SUMMING DIFFERENTIAL A PROBE U6 1 OFFSET LOW FREQUENCY y LFSIGNAL i V AMPLIFIER 25 35s PT 2 n i REJECT 2 x 54715A PLUG IN CONTROL P O UA POWER PROBE POWER ASSY gp aok SG Hoo DATA um 6 OFFSET MUX B P O U4 11 OFFSET V ut 2 U2 3 b g POWER V P O PROBE SENSE 5 SUPPLIES n 4 HV 4 25V Differential Probe System Block Diagram 01141805 59 Service Theory of Operation Differential Probe The probe contains a two path differential amplifier with unity gain It is implemented ona double sided surface mount PC board with the high frequency path on one side an
31. TC 0 100 24546 4 1 8 0 101 R25 2100 3161 RESISTOR TRMR 20K 10 TKF SIDE ADJ 32997 13006 1 203 R26 2100 3056 RESISTOR TRMR 5K 10 TKF SIDE ADJ 17 TRN 32997 13006 1 502 R27 0757 0199 RESISTOR 21 5K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 2152 F R28 0757 0199 RESISTOR 21 5K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 2152 F R29 0757 0442 RESISTOR 10K 1 0 125W TF TC 0 100 24546 4 1 8 0 1002 R30 0757 0442 RESISTOR 10K 1 0 125W TF TC 0 100 24546 4 1 8 0 1002 R30 0757 0280 RESISTOR 1K 1 0 125W TF TC 0 100 24546 4 1 8 0 1001 R32 0757 0460 RESISTOR 61 9K 1 0 125W TF TC 0 100 24546 4 1 8 0 6192 R33 39 NOT ASSIGNED R40 0757 0123 RESISTOR 34 8K 1 0 125W TF TC 0 100 28480 0757 0123 R41 2100 4250 RESISTOR VAR 10K 20 28480 2100 4250 R42 2100 4250 RESISTOR VAR 10K 20 28480 2100 4250 R43 0757 0458 RESISTOR 51 1K 1 0 125W TF TC 0 100 24546 CT4 1 8 T0 5112 F R44 0683 2755 RESISTOR 2 7M 1 0 25W TF TC 0 100 28480 10683 2755 R45 0698 4517 RESISTOR 127K 1 0 125W TF TC 0 100 24546 4 1 8 0 1273 R46 0698 3271 RESISTOR 115K 1 0 125W TF TC 0 100 24546 4 1 8 0 1153 R47 0698 8961 RESISTOR 909K 1 0 125W TF TC 0 100 28480 0698 8961 R48 0757 0199 RESISTOR 21 5K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 2152 F 83 Service Replaceable Parts Power Supply Replaceable Parts Ref Des Part O
32. USEHOLDER 6 3A 250A 28480 12110 0642 E2 2110 0565 FUSEHOLDER CAP 28480 2110 0565 2110 0201 FUSE 0 25A 250V TD 28480 2110 0201 H1 0515 1579 SCREW MACHINE M5 18mm LG 28480 0515 1579 HS1 01142 21101 1 SINK 28480 101142 21101 81 Service Replaceable Parts Power Supply Replaceable Parts Ref Des Part Oty Description Mfr Mfr Part Number Code Number J1 1252 4731 1 CONNECTOR AC PWR 28480 11251 4743 J2 1252 1487 1 CONN RECT D SUBMIN 9 CKT remote 28480 11252 1487 J3 1252 3935 1 CONNECTOR ROUND 8 CKT probe 28480 1252 3134 MP1 1400 1604 1 LED MOUNT 28480 1400 1604 MP2 1205 0732 4 SPRING CLIP 28480 1205 0732 MP3 0361 0685 3 RIVET BLIND DR PIN 0 125DIA 28480 0361 0685 MP4 0340 1211 3 INSULATOR THERMAL 28480 0340 1211 MP5 6 NOT ASSIGNED MP7 1400 0249 1 CABLE TIE 0 062 0 625 DIA 0 091 WD NYL 16956 08 465 GRY MP8 01142 24702 1 TRANSFORMER SUPPORT 28480 01142 24702 9 01142 28801 1 WASHER TRANSFORMER SUPPORT 28480 101142 28801 R1 2 NOT ASSIGNED R3 0757 0442 4 RESISTOR 10K 1 0 125W TC 0 100 24546 4 1 8 0 1002 R4 0757 0465 RESISTOR 100K 1 0 125W TF 0 100 24546 4 1 8 0 1003 R5 0757 0199 5 RESISTOR 21 5K 1 0 125W 0 100 24546 4 1 8 0 2152 R6 0757 0199 RESISTOR 21 5K 1 0 125W TC 0 100 24546 4 1 8 0 2152 R7 0698 44
33. User and Service Guide Publication number 01141 97002 July 2004 For Safety and Regulatory information see the pages at the end of this book Copyright Agilent Technologies 2000 2004 All Rights Reserved Agilent Technologies 1141A Differential Probe and 1142A Probe Control and Power Module Agilent Technologies 1141A Differential Probe and 1142A Probe Control and Power Module This manual contains information for use and service of the differential probe system the 1141A Differential Probe and 1142A Probe Control and Power Module In this document the two models will be treated as system Each of the two instrument models that make up the differential probe system has a serial number sticker The sticker for the 1141A Differential Probe is inside the probe in the bottom cover See chapter 3 for disassembly procedure The 1141 1142 probe system allows measurement of small differential signals in the presence of much larger common mode signals It has the following major features 200 MHz bandwidth Variable offset dc reject coupling Remote operating capability The variable offset capability can be used to measure small ac signals in the presence of much larger dc levels Remote operation of key features allows the use of the probe system in automatic test situations The probe can be used with an oscilloscope spectrum analyzer or any instrument where differential probing is required
34. aid and resuscitation is present Do not install substitute parts or perform any unauthorized modification to the instrument Capacitors inside the instrument may retain a charge even if the instrument is disconnected from its source of supply Do not operate the instrument in the presence of flammable gasses or fumes Operation of any electrical instrument in such an environment constitutes a definite safety hazard Do not use the instrument ina manner not specified by the manufacturer To clean the instrument If the instrument requires cleaning 1 Remove power from the instrument 2 Clean the external surfaces of the instrument with a soft cloth dampened with a mixture of mild detergent and water 3 Make sure that the instrument is completely dry before reconnecting it to a power source Safety Symbols Instruction manual symbol the product is marked with this symbol when it is necessary for you to refer to the instruction manual in order to protect against damage to the product Hazardous voltage symbol Earth terminal symbol Used to indicate a circuit common connected to grounded chassis
35. al conditions and the user s experience concerning need for testing will contribute to verification requirements Calibration Test Record The results of the calibration tests may be tabulated in the Calibration Test Record provided at the end of the calibration tests The Calibration Test Record listed the calibration tests and provides an area to mark test results The results recorded in the Calibration Test Record during initial inspection may be used for later comparisons of the tests during periodic maintenance troubleshooting and after repairs or adjustments Calibration Test Procedures Procedures may be done individually or in any order Allow the instrument to warm up for at least 30 minutes prior to beginning calibration tests 27 Calibration Tests and Adjustment dc Gain Accuracy dc Gain Accuracy This test checks the de gain accuracy of the differential probe and the dc accuracy of the differential probe with attenuator and adapters Specification Probe alone 2 with attenuator adapter 4 Equipment Required Recommended Equipment Agilent Required Critical Specifications Model Part ac dc Calibrator 100mVto7V or E3632A dc Power Supply 199 mVto7V DVM 0 5 accuracy 10 resolution 3458A E34401A Load BNC Feedthrough 50 Q Pasternack Enterprises PE6008 50 or Huber Suhner 22543742 Cables 2 BNC 50 Q 10503A Adapters 2 BNC f to dual banana 1251 2277 Test Board No su
36. amplitude as shown in V reading for channel 1 Adjust R11 slowly and use CLEAR DISPLAY frequently to restart averaging Low Frequency Response and CMRR This adjustment sequence continues from the HF Gain and HF CMRR adjustments Adjust R14 and C4 for pulse response and adjust C6 for low frequency CMRR Change the function generator settings to Square wave 2 5 kHz 600 44 Calibration Tests and Adjustment Adjustment Procedure 2 Change the oscilloscope settings to Menu Selection Setting TIMEBASE time div 50 us div CHAN 1 sensitivity 100 mV div 3 Carefully connect the input of the probe to the test board in the position shown in the figure below signal to input Figure 2 17 Signal to input 2 4 Adjust R14 LF Gain and C4 LF BANDWIDTH for flattest pulse top see figure below Again adjust slowly and press CLEAR DISPLAY frequently to restart averaging Figure 2 18 C4 LF BANDW Ju 5 D Tj mp cs Rb mi Eu aj 01141 811 1 03 LF BANDWIDTH R14 and C4 Adjustment 45 Figure 2 19 Calibration Tests and
37. and a compatible 50 Q input is available Contents Operating the Probe Accessories Supplied 6 Accessories Available 8 inspect the probe 9 Using the probe with other instruments 9 Recommended Test Equipment 9 Calibration Tests and Adjustment Equipment Required 26 The Test Board 26 Calibration Tests 27 Gain Accuracy 28 Bandwidth 34 CMRR Test 36 Calibration Test Record 39 Adjustments 40 Probe Adjustment 40 Adjustment Procedure 42 Attenuator Adapter Adjustment 49 Service Introduction 54 Performance Specifications and Characteristics 55 General Characteristics 58 Contents Theory of Operation 59 Differential Probe 60 Control and Power Module 60 Attenuator Adapters 61 Test Board 62 Service Policy 63 Troubleshooting 64 Probe Troubleshooting 64 Probe Control and Power Module Troubleshooting 64 Removing and Replacing Assemblies 66 Differential Probe 66 Probe Adapters 68 Probe Control and Power Module 70 Replaceable Parts 71 Parts List 71 Ordering Information 71 Direct Mail Order System 71 Manufacturers Codes 72 Exploded View 73 Operating Probe Operating the Probe Accessories Supplied Introduction This chapter shows you how to connect and operate the 1141A Differential Probe and 1142A Probe Control and Power Module as a differential probe system Accessories Supplied The following items are supplied as part of the 1141A 1142A probe sys
38. ator the corner is 1 5 Hz e The low frequency CMRR when using the ac adapter is not as good as when using the probe alone or the probe with a 10x or 100x adapter If you measure a node having a high dc potential the blocking capacitors in the ac adapter will charge to that potential After making such measurements discharge the capacitors by grounding both inputs of the ac adapter This will prevent damage by a high voltage discharge into sensitive circuitry when the next measurement is made 20 1 2 Operating the Probe Recommended Test Equipment To use ac coupling Attach the ac coupling adapter to the input of the probe or the input of the attenuator adapter On the 1142A press Local and Zero offset Remote operation For automatic test applications the coupling and offset functions provided by the 1142A Probe Control and Power Module can be remotely controlled through a connector on the rear panel of the module The connection is through a standard 9 pin female D subminiature connector This style is the same as that used on some personal computer monitor cables which provides an economical way to connect the 1142A to the controller interface on an automatic test system The following table gives the connections Remote Input Connections Pin Function Pin Function Connector 1 Function Select 1 A1R 6 Function Select 0 AOR 2 Digital common 7 N C 600900 3 N C 8 N C 9000 4 External off
39. being changed without notice in future editions Further to the maximum extent permitted by applicable law Agilent disclaims all warranties either express or implied with regard to this manual and any information contained herein including but not limited to the implied warranties of merchantability and fitness for a particular purpose Agilent shall not be liable for errors or for incidental or consequential damages in connection with the furnishing use or performance of this document or of any information contained herein Should Agilent and the user have separate written agreement with warranty terms covering the material in this document that conflict with these terms the warranty terms in the separate agreement shall control Technology Licenses The hardware and or software described in this document are furnished under a license and may be used or copied only in accordance with the terms of such license Restricted Rights Legend If software is for use in the performance of a U S Government prime contract or subcontract Software is delivered and licensed as Commercial computer software as defined in DFAR 252 227 7014 June 1995 or as a commercial item as defined FAR 2 101 a or as Restricted computer software as defined in FAR 52 227 19 June 1987 or any equivalent agency regulation or contract clause Use duplication or disclosure of Software is subject to Agilent Technol
40. bstitute 01141 66514 Probe Gain Test Procedure 1 Connect the probe and test equipment as shown in figure 2 2 28 Calibration Tests and Adjustment dc Gain Accuracy Figure 2 2 BNC to BNC Cable Banana Connector Digital Volt 0000000 Meters lt lt 000000 Source lt 50 ohm Feedthrough Terminator Connector 1142A Probe Control and Power Module BNC Cable 7 Probe Amp 014202 2 Set up 1142 probe control and power module as follows Set the Local Remote push button to Local b Under DC Couple press the Zero offset button 3 With the 1141A Probe Amp disconnected from the test PCA adjust the Offset Null control on the 1142A until the DVM reads If the probe output voltage cannot be set to OV subtract this voltage from the subsequent measurements in this test 4 Connect the input of the Probe Amp to the test board in the position shown in Figure 2 4 on page 31 Adjust the DC Source to output 100 mV nom Record the 1 measurement from the top DVM in figure 2 2 Record the measurement from the bottom DVM in figure 2 2 Connect the Probe Amp to measure a negative voltage as shown in figure 2 3 Record the measurement from the bottom DVM in figure 2 2 00 10 Q0 29 Figure 2 3 10 NOTE NOTE Calibration Tests and Adjustment dc Gain
41. ce the amplitude of the input signal Ifthe signal is incorrect check the power supply voltages from the 1142A Probe Control and Power Module Use the cable diagram on the next page Troubleshoot the cable with an ohmmeter Use the cable diagram on the next page Probe Control and Power Module Troubleshooting The circuitry consists of simple power supplies operational amplifiers and TTL Use conventional troubleshooting techniques A complete parts list component locator and schematics are provided later in this chapter 64 Service Troubleshooting Figure 3 7 5 45V 45V TOC HV 74 157 7 LRS R6 R29 2127 RS 5 1 FUNSELO PLOK 10K is TFUNSEL1 AIR 4 1 gt 1 gt gt 5 SEL1 2 2 5 828 62 2 INTERLATCHED 82 LOCAL 1 VARIABLE FINE COARSE DC REJECT 5 0HZ 7 SHIELD m 11 wi E p d cm ____ 9 1UF 45V VP a d 3 LT1012 c22 9 01UF a gt 6 OF ST 3 2 5HZ 0 05 2 COUPLE ZERO OFFSET VARIABLE OFFSET U10 qi 6 1 VIEW 1142A Probe Control and Power Module 65 CAUTION CAUTION CAUTION Service Removing and Replacing Assemblies Removing and Replacing Assemblies This section contains procedures for the removal and replacement of
42. d the low frequency path on the other The two paths are split directly after the differential input connections High Frequency Path The positive and negative inputs are ac coupled at 33 Hz into identical impedance converters The HF CMRR adjustment balances the gain at the outputs of the impedance converters The impedance feed a semi custom differential amplifier An additional negative input to the differential amplifier brings in the sum of the low frequency and feedback signals The FREQ COMP adjustment provides variable high frequency peaking of the differential amp The output amp provides two signals A feedback signal is summed with the low frequency signals and the output signal is the final output of the probe Overall probe gain is set by the HIGH FREQ GAIN adjustment The entire signal portion of the high frequency path is implemented on a hybrid IC Support circuitry includes bias for the impedance converters and a bias supply for current sources on the hybrid Low Frequency Path The bandwidth of the low frequency path is approximately 75 KHz The positive and negative inputs are dc coupled into identical inverting op amps with gain of 0 5 They provide precision 1 input impedance for the probe The LOW FREQ BANDWIDTH adjustments match the gain and phase of the low frequency path to that of the feedback from the probe output One of the two adjustments is set to match the properties of the feedback and the other is to match
43. de Real Time Memory Depth Automatic Sample Rate Automatic Averaging Enabled of avg 32 4 Onthe oscilloscope measure the peak to peak voltage of the channel 1 signal and record the reading Vp p 1 5 Disconnect BNC cable from channel 1 input and connect it to the BNC connector on the test board 6 Connect the output of the probe to the channel 1 input 7 Carefully connect the input of the probe to the test board in the position shown in the figure below signal to input Figure 2 14 Signal to input 43 8 Figure 2 15 9 10 Figure 2 16 11 12 13 Calibration Tests and Adjustment Adjustment Procedure Center adjustment R11 HF CMRR see following figure R11 01141 11141 03 R11 CMRR Adjustment Adjust R9 HF GAIN so the V 1 measurement is the same as in step 4 within 0 5 Make the adjustment slowly so the oscilloscope display has time to react to signal averaging Press CLEAR DISPLAY occasionally to restart averaging which gives a quicker indication of changes Carefully connect the probe to the test board in the position shown in the figure below signal to both inputs CT LT O O Signal to both inputs Set the function generator output to 1 0 Vp p On the oscilloscope set the channel 1 sensitivity to 1 00 mV div Adjust R11 for minimum signal
44. e between the two voltage dividers The two high frequency adjustments are electrically identical Each adjusts the high frequency compensation of one of the voltage dividers To meet both pulse response and CMRR characteristics they are adjusted differently Briefly the adjustment procedure is a Adjust the positive high frequency response HF RESP for the best pulse response using a 3 5 kHz square wave b Adjust the negative high frequency response HF RESP and Low frequency CMRR LF CMRR for best CMRR using a 3 5 kHz square wave The following equipment is required for this procedure Procedures are based on the model or part number recommended Equipment Required Equipment Required Critical Specifications Recommended Model Part Function Generator 3 5 kHz to 16 Vp p 33120A Oscilloscope 100 MHz at 1 mV div 54830B Probe Power Module No substitute 1141A 1142A Test Board No substitute 01141 66504 Cable BNC 50 Q 9 inch 10502A Cable BNC 50 Q 36 inch 10503A Alignment tool Flat blade supplied accessory 8710 1961 Sprague Goodman part GTT 5G 49 Calibration Tests and Adjustment Attenuator Adapter Adjustment Adjustment Procedure The attenuator must be adjusted when installed on the 1141A probe with which it will be used The specifications and characteristics will not be met if the attenuator adapter is adjusted with one differential probe then used with another Remove the prob
45. e pins from the attenuator adapter and differential probe then attach the adapter to the probe Set the 1142A front panel switches to Local and Zero offset Use the 9 inch BNC cable to connect the function generator to the test board The short cable minimized ground loop voltages Set up the function generator e Square wave e 3 5 kHz e 3 0 Vp p for 10x adapter and 16 Vp p for a 100x adapter Use the long BNC cable to connect the Trig Out of the function generator to the EXT TRIG of the oscilloscope Set up the oscilloscope then set the following parameters Menu Selection Setting TIMEBASE time div 50 us div CHAN 1 sensitivity 50 mV div input R 50 Q DC TRIG mode trg d source EXT level 1 00000 V ACQUISITION Sampling Mode Real Time Memory Depth Automatic Sample Rate Automatic Averaging Enabled of avg 32 50 Calibration Tests and Adjustment Attenuator Adapter Adjustment 7 Connect the adapter probe combination to the test board in the position shown in the figure below Figure 2 23 Signal to input 8 Adjust the HF RESP for best overall pulse response the flattest pulse top Use the figure below for adjust locations Figure 2 24 Adjustment Locations 9 Change the function generator to 10 10x adapter adjustment only 10 On the oscilloscope press CHAN and set the sensitivity to 1 mV div 51 Figure 2 25 11 12 Calibration Tests and Adju
46. ed Test Equipment e Offset null zeroes the dc level at the output of the probe The range of adjustment is about 4 mV DC Reject Gain adjusts the gain of the dc reject circuit to accurately null the component of an input signal The range of adjustment is about 0 5 Figure 1 5 142A Probe Control and Power Module Variable DC R t DC C Local ouple Course 9457 a Renate 005 5 0Hz O SHz Offset Offset Line O 6000 1142A Front Panel Equipment Needed The following equipment is necessary for initial adjustment 5 power supply DVM that can measure 25 nV 50 Q BNC feedthrough terminator 01141 66504 test board Equipment Setup Use the following procedure to setup the differential probe system for initial adjustment CAUTION Do not exceed 7 V when using the test board for this procedure If the voltage is too high it will cause excessive power dissipation in the 50 termination on the test board 1 Use the probe setup procedure to set up the probe system 2 Connect a 50 BNC feedthrough terminator to the output of the probe 3 Disconnect all accessories from the input of the probe 4 Connect the DVM to measure the dc output of the probe at the 50 Q load 12 Figure 1 6 w Operating the Probe Recommended Test Equipment Set up the 1142A Set the L
47. est Equipment Use extension leads and similar connection accessories carefully Extension leads compromise the high frequency specifications of the probe CMRR is particularly sensitive to unbalanced input parameters To prevent pickup of stray fields when you use extension lead either the ones supplied with the 1141A or others dress them carefully as follows e Connect the leads at right angles to the circuitry under test e Keep the leads as parallel as possible before they connect to the probe Mini Grabbers Mini grabbers can be attached to the probe or adapter through the extension leads Remove the probe tip caps and tips Attach the extension leads to the probe or adapter Attach the mini grabbers to the extension leads Circuit Connector Posts These 0 025 inch square posts can be used to connect either directly to the probe or to the extension leads Solder the posts directly into your circuitry or use them to make extension leads that plug into the inputs of the probe or adapters Shielded Signal Leads The shielded signal leads allow connection to points in a circuit that are up to 10 inches apart The leads are shielded to within approximately 1 2 inch of the end of the lead so they minimize pick up due to stray fields from adjacent circuitry Connect the end with the ground connector to the probe pins and ground of the differential probe or adapter Connect the free ends of the leads to 0 025 inch square or 0 030 inch r
48. ever the way the probe is connected into the circuitry being tested can have a big influence in the overall result of the measurement especially at high frequencies The following things can affect the effective CMRR of a test setup e The connection to the circuit under test The method used to connect the probe is important because it involves the symmetry of the differential input circuitry For example using different lengths of wire to connect the circuit to the two probe inputs unbalances the inductance and capacitance at the inputs The effective CMRR will be reduced especially at high frequencies Additionally coupling from adjacent circuitry will be less balanced e The impedance of the source This is another instance where the symmetry of the differential circuit is important The impedance of the source forms a network with the input impedance of the source forms a network with the input impedance of the connections and the probe This network determines the frequency response for the measurement If each side of the differential source has a different impedance the frequency response of each side will be different and the unbalance is reflected in a reduced CMRR Of course lower source impedances have less effect on the frequency response of the measurement e The ground connection A poorly located ground connection allows ground loops to add to the common mode signal e Frequency Frequency is the most important factor in C
49. f the input signal LFSIG is an input to U6 an inverting amplifier and low pass filter Multiplexer U3 selects one of three capacitors to set a roll off frequency of 0 05 0 5 or 5 Hz The output of U6 is selected again by U3 as the input to the offset amp When the output of the offset amp is summed into the low frequency path the result is cancellation of the dc component of the input signal Front panel screwdriver adjustment DC Reject Gain adjusts the gain of the reject circuit Local and Remote Control The front panel switch controls the dc reject and offset functions It also selects remote operation which allows control through the rear panel remote input connector Power Supply The supply provides 6 V and 15 V for the probe and analog control circuitry as well as 5 V for the digital control circuitry Attenuator Adapters The 10x and 100x Attenuator Adapter are similar A ceramic substrate carries two attenuators one for each input polarity A variable resistor adjusts the low frequency balance LF CMRR between the two attenuators The high frequency adjustments are the same for each attenuator Each attenuator is adjusted differently One attenuator is adjusted for optimum pulse response and the other for best high frequency CMRR OUT Q RESP CMRR Q V V ty HF RESP IN MW 4 OUT is T 01141802 Attenuator Adapter Simplified Schematic 61 Service Theo
50. gn with the holes in the inner housing 5 Seat the thumbwheel screw first then the output pins into the appropriate holes in the inner housing 6 Once the two housings are nearly together press them together firmly until the tabs click into place 69 WARNING WARNING A Service Removing and Replacing Assemblies Probe Control and Power Module Use the following procedure to disassemble the probe control and power module Hazardous voltages exist on the power supply To avoid electrical shock adhere closely to the following procedures Remove the power cord Remove four flathead screws and remove the top cover Be sure to reconnect the safety ground when reassembling the instrument Unplug the safety ground from the tab on the rear panel of the instrument Note the orientation of the knobs Remove the two knobs On the bottom of the instrument remove the 5mm screw that fastens the transformer support Remove the following pan head screws Three directly on PC board Two input connector Two heatsink Remove the PC board Slide it slightly forward so parts will clear rear panel then lift the rear of the board out while sliding it backwards Remove the two heatsink spacers from the standoffs that were directly under the heatsink Reverse the procedure to reassemble the control and power supply 70 Service Replaceable Parts Replaceable Parts This sectio
51. here the two pins at the rear of the top cover enter the holes in the PC assembly Position the cable wires away from these two areas Otherwise when the bottom cover is closed part of it will pinch wires that are laying over these areas b Insert the pins at the front of the bottom cover into the holes at the front of the top cover Close the two covers together and fasten with the probe clamp ring 48 Calibration Tests and Adjustment Attenuator Adapter Adjustment Attenuator Adapter Adjustment The following procedure should be used if it is necessary to adjust an attenuator adapter Attenuator adapters have only characteristics they do not have any specifications An adapter will need adjustment only if one or more of the following occurs adapter is to be used on a different 1141A probe that it was calibrated with last adapter needs to be optimized to requirements for a special measurement adapter is suspected of needing adjustment Attenuator adapters should not be adjusted as part of routine maintenance The design necessary to give the high CMRR and high impedance of the attenuators makes adjustment delicate Additionally because of broadband noise a spectrum analyzer should be used to verify adjustment quality Each attenuator contains two identical voltage dividers on a ceramic substrate There are three adjustments The low frequency CMRR adjust the low frequency balanc
52. in the figure below use the grounding screw to reinstall the ground block on the PC assembly N 01141E13 Attaching Ground Block to Probe PC Assembly The ground block provides a mechanical and electrical connection when the probe PC assembly is connected to the test board Connect the probe power connector to the PROBE connection on the rear of the 1142A Probe Control and Power Module Connect the mains power to the 1142A Set the 1142A front panel switches to Local and Zero offset Adjustment Procedure Unless specified elsewhere the procedures must be followed in the order given The only adjustment which may be done separately is HF COMP the high frequency compensation HF Gain and HF CMRR This adjustment sequence adjusts the HF Gain for unity gain at 500 kHz and the HF CMRR for minimum with a 500 kHz common mode signal Set up the function generator e Sine wave 500 kHz 600 mV Use BNC cables to connect the function generator to the oscilloscope Generator OUTPUT to oscilloscope channel 1 input Generator TRIG OUTPUT to oscilloscope EXT TRIG 42 Calibration Tests and Adjustment Adjustment Procedure 3 Onthe oscilloscope then press CLEAR DISPLAY Press AUTOSCALE then set up the following parameters Menu Selection Setting TIMEBASE time div 500 ns div CHAN 1 sensitivity 100 mV div input R 50 Q DC TRIG mode trg d source EXT level 1 00000 V ACQUISITION Sampling Mo
53. ith the measurement The key characteristics are e The user manually null the dc component with the offset adjustment Offset is dc coupled so there is no low frequency roll off e Probe CMRR specifications are not compromised as happens when the ac coupling adapter is used e The voltage offset range is 20 V with the probe alone 200 V with the 10x attenuator and 500 V with the 100x attenuator With the 100x attenuator the offset range is restricted by the maximum input voltage rating rather than the operating range of the offset To use offset Remove the ac adapter if it is installed On the front panel of the 1142A press Local and Variable offset Adjust the Coarse and Fine Variable Offset until the signal is displayed on the screen of the oscilloscope ac Adapter The ac adapter must be used when the dc component of the signal exceeds the operating range of the dc reject or offset methods The ac adapter block the and low frequency component of the input by forming a high pass filter with the input impedance of the probe or adapter The key characteristics are e The ac adapter safely blocks 200 Vdc when attached directly to the probe or 500 Vdc when attached to a 10x or 100x adapter e The probe and adapters have different input impedances so they have different low frequency corners with the ac adapter When the ac adapter is directly on the probe the 3dB corner is 15 Hz When the ac adapter is on an attenu
54. lange on the strain relief has a notch that fits over a protrusion in the top cover 67 CAUTION Figure 3 9 Service Removing and Replacing Assemblies Note where the two pins at the rear of the top cover enter the holes in the PC assembly Position the cable wires away from these two areas When the bottom cover is closed part of it will pinch wires that are laying over these areas b Insert the pins at the front of the bottom cover into the holes at the front of the top cover Close the covers together and fasten with the probe clamp ring If the covers do not fit together tightly and easily check for pinched wires see caution above Probe Adapters Use the following procedure to disassemble the probe adapters The adapter housing consists of two plastic parts one of which slides into the other The parts are held together by the spring effect of two plastic tabs on the inner part Mechanically the ac adapter is about the same as the 10x and 100x attenuator adapters The attenuator adapters have an extra ground connector which connects the substrate ground to the thumbwheel screw and plating inside the housing Disassemble Adapter Remove the probe tip caps and probe tips from the adapter input Hold the adapter in one hand taking care not to block the output end of the adapter the end which attaches to the probe Note the view of the input end of the adapter in the figure below The arrows indicate the holding tabs
55. n contains information for ordering parts Service support for the 1141A Differential Probe is to the assembly level Service support for the adapters is as complete assemblies except for the probe tip caps and the probe tips Service support for the 1142A Probe Control and Power Module is to the component level Parts List The replaceable parts lists include all parts relevant to the applicable service levels The information given for each part consists of the following e Reference designator e Part number e Total quantity Qty in instrument or on assembly The total quantity is given once and at the first appearance of the part number in the list Description of part e Typical manufacturer of part in a five digit code Ordering Information To order a part in the material part list quote the part number indicate the quantity desired and address the order to the nearest Agilent Technologies Sales Office To order a part not listed in the material list include the instrument part number instrument serial number a description of the part including its function and the number of parts required Address the order to the nearest Agilent Technologies Sales Office Direct Mail Order System Within the USA Agilent Technologies can supply parts through a direct mail order system There are several advantages to this system e Direct ordering and shipment from the Agilent Technologies parts center in California USA No
56. nd leads 14 grounding 18 H high frequency compensation 47 gain amp CMRR adjustment 42 high frequency path 60 humidity 58 I impedance output 55 initial adjustment 11 input impedance 55 input range differential 55 input voltage maximum 55 inspecting 9 L line voltage 10 local control 61 locator table 85 low frequency response 44 low frequency path 60 87 Index M making measurements 13 manufacturer s codes 72 maximum input voltage 55 mini grabbers 15 N noises 55 offset 20 offset functions 61 offset null 11 operating environment 58 operating range 55 ordering information 71 output impedance 55 overload recovery 55 parts list 71 78 performance specification 55 power module 60 disassembly 70 troubleshooting 64 power requirements 10 58 power supply 61 probe adapter disassembly 68 reassembly 68 probe adjustment 40 probe control disassembly 70 troubleshooting 64 probe gain test 28 probe tips 14 procedure attenuator adjustment 50 bandwidth 34 CMRR test 36 probe adjustment 42 probe gain 28 probe preparation 41 R recommended test equipment 9 record calibration 39 remote control 61 remote functions 22 remote input connection 21 remote offset input 22 remote operation 21 removing assemblies 66 replaceable parts 71 replaceable parts list 78 replacing assemblies 66 rise time specification
57. o the differential probe with or without adapters A BNC connector connects the test board to a cable from the signal generator The board includes a 50 Q termination two 100 Q resistors The power rating of the 50 termination is 1 0 W Keep the signal input below 7 Vdc or rms to avoid degrading the termination Once the probe tip caps and probe tips have been removed the probe can be connected to the test board in one of three ways as shown in the figure below At each position of the probe probe inputs are connected to a different combination of signal and ground A separate terminal on the test board connects the ground of the probe to the signal of t o3 0444204 Test Board Showing Probe Positions 26 Calibration Tests and Adjustment The Test Board Calibration Tests These procedures test the probe s electrical performance using applicable specifications given in Performance Specifications and Characteristics on page 55 as performance standards Specifications applicable to individual tests are noted at the test for reference Testing Interval The calibration testing procedures may be performed for incoming inspection of the instrument and should be performed periodically thereafter to ensure and maintain peak performance The recommended test interval is yearly or every 2 000 hours of operation Amount of use environment
58. ocal Remote push button to Local b Under DC Couple press Zero offset Set the power supply output to 5 V Arrange a connection between the power supply and the test board The negative terminal of the supply should connect to the shield of the test board BNC If your power supply has standard binding posts you can connect a banana to BNC adapter to the supply and connect a BNC cable between the supply and the test board Adjustment Warm up the 1141A for 30 minutes before making adjustments With the 1141A probe inputs unconnected adjust Offset Null on the 1142A for a minimum reading on the DVM The voltage swing of the adjustment is approximately 4 mV On the 1142A under DC Reject press 5 0 Hz Read and record the reading on the DVM mV Connect the probe to the test board in the position shown below signal to input Signal to input After DVM reading stabilizes adjust DC Reject Gain to the reading recorded in step 3 With 5 supply the voltage swing is approximately 12 5 mV With a lower supply the voltage swings proportionally less Using the Accessories The 1141A Differential Probe and accessories are designed to provide a variety of ways to connect to circuitry and make measurements In the descriptions any method used to connect to the probe signal inputs also applied to the adapters The figure below shows in a general way the use of accessories 13 Figure
59. ogies standard commercial license terms and non DOD Departments and Agencies of the U S Government will receive no greater than Restricted Rights as defined in FAR 52 227 19 c 1 2 June 1987 U S Government users will receive no greater than Limited Rights as defined in FAR 52 227 14 1987 or DFAR 252 227 7015 b 2 November 1995 as applicable in any technical data Manual Safety Notices CAUTION A CAUTION notice denotes hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in damage to the product or loss of important data Do not proceed beyond a CAUTION notice until the indicated conditions are fully understood and met WARNING A WARNING notice denotes hazard It calls attention to an operating procedure practice or the like that if not correctly performed or adhered to could result in personal injury or death Do not proceed beyond a WARNING notice until the indicated conditions are fully understood and met Agilent Technologies P O Box 2197 1900 Garden of the Gods Road Product Safety Notices This apparatus has been designed and tested in accordance with IEC Publication 1010 Safety Requirements for Measuring Apparatus and has been supplied ina safe condition This is a Safety Class I instrument provided with terminal for protective earthing Before applying power verify that
60. ound pins in your circuitry or to the mini grabbers Each lead has an input capacitance of approximately 15 pF This capacitance may limit the bandwidth of your measurement depending on the impedance of the circuit Also CMRR may be affected because of slight differences between the input capacitance of the two leads CMRR is also affected by differences in impedance between the two measurements points 15 Operating the Probe Recommended Test Equipment Adapters There are three adapters for use with the differential probe Two adapters are attenuators a 10x and al00x The other is an ac adapter for blocking dc from the probe input The adapters are installed on the probe after the probe tip caps and probe tips have been removed The adapter fastens to the probe using a thumb wheel located on the underside of the adapter the figure below shows a good way to hold the probe while attaching the adapter 1 Remove the probe tip caps and probe tips from the probe 2 Fit the adapter over the end of the probe and rotate the thumb wheel with your finger until the adapter fits snugly A snug fit is important because the ground is maintained through the thumb wheel screw A loosely attached adapter compromises the mechanical and electrical integrity of the combination 2756 129 Attaching Adapters Figure 1 8 16 Figure 1 9 Operating the Probe Recommended Test Equipment Adapter
61. quency adapter to corner differential probe 1 1 Remote Control Yes Yes No CMRR No No Yes degradation Low frequency No Yes Yes degradation Isolated external dc reference and control signals are needed dc Reject dc Reject is the best method of eliminating the dc component of a signal when dc is not a factor in the measurement The key characteristics are The low frequency component from dc to the selected corner frequency is automatically nulled by the reject circuitry Probe CMRR specifications are not compromised as happens when the ac coupling adapter is uses There is a selectable low frequency corner with 3dB points at 0 05 Hz 0 5 Hz or 5 0 Hz Recommended Test Equipment The voltage reject range is 20 V with the probe alone 200 V with the 10x attenuator and 500 V with the 100x attenuator 19 CAUTION N N Operating the Probe Recommended Test Equipment To use dc reject Remove the ac adapter if it is installed On the front panel of the 1142A press Local Under DC Reject on the front panel press 5 0 Hz or 0 5 Hz individually or 5 0 Hz and 0 5 Hz simultaneously to get 0 05 Hz Within the frequency and voltage characteristics noted elsewhere in this manual low frequencies are nulled from the input signal Offset Offset is the best method to use when the low frequency corners associated with dc reject and the ac adapter interfere w
62. robe and attenuator adapters There are no service adjustments for the 1142A Probe Control Module Adjustment Interval None of the adjustment procedures that follow should be considered for a routine maintenance plan The differential probe and attenuator adapters should be adjusted under conditions specified at the beginning of the respective procedures Warm up the instrument for 30 minutes before starting adjustment procedures Probe Adjustment This procedure adjust the high frequency and low frequency paths on the 1141A Differential Probe Do not perform this procedure as a part of routine maintenance Perform the procedure only if the probe does not meet specifications or has been repaired You are going to remove the covers of the probe so the assembly inside will be exposed while under power The PC assembly will be electrically and mechanically vulnerable Do these adjustment procedures in an ESD safe area Avoid inadvertent contact between the powered assembly and nearby tools and equipment Avoid mechanical damage by carefully handling the exposed assembly and cables 40 Calibration Tests and Adjustment Probe Adjustment The following equipment is required for this procedure Procedures are based on the model or part number recommended Equipment Required Equipment Required Critical Specifications Recommended Agilent Model Part Function Generator 2 5 kHz 1 Vp p 33120A Oscilloscope 3
63. ry of Operation Test Board The test board is a device for conveniently connecting test signals to the differential probe The probe can be connected to the board with the signal to the positive negative or both inputs Figure 3 6 J1 J3 R1 R2 J4 100 100 J2 J5 J6 01141808 Test Board Schematic 62 Service Service Policy Service Policy For parts of the 1141A 1142A probe system that are complex the service policy is for assembly level repair For parts of the system with simple circuitry the service policy is component level repair The service policy for the 1141A Differential Probe is assembly level repair Assemblies include the PC assembly and cable The PC assembly is an exchange assembly A repaired and tested assembly is shipped upon receipt of the defective assembly The attenuator and ac coupling adapters are shipped as complete assemblies The service policy for the 1142A Probe Control and Power Module is component level repair 63 Service Troubleshooting Troubleshooting Use the following paragraphs to assist in troubleshooting problems with the 1141 A 1142A Differential Probe Probe Troubleshooting To troubleshoot the probe Apply a known signal to the input of the probe Check for an identical output at the output coax to the cable This connection is the one soldered to the PC board If the probe output cable is not terminated or the coax is open the output signal will be about twi
64. set common 9 External offset 01141E08 5 Shield To minimize dc offset errors and potential noise coupling electrically isolate all connections between the Remote Input connector and the controlling system 21 Operating the Probe Recommended Test Equipment Function Select The easiest way to control the function select lines is contact closures between the lines and Digital common pin 2 of the remote input connector TTL compatible control signals can be used but to avoid problems with ground loops they must be electrically isolated The following truth table shows the functions provided by the function select lines For the Remote Inputs 0 represents a closure and 1 represents an open circuit Remote Functions Select Truth Table Remote Input Function AIR AOR Pin 1 Pin 6 0 0 0 05 Hz Reject 0 1 0 5 Hz Reject 1 0 5 Hz Reject 1 1 DC Couple Variable Offset The remote variable offset can be used when the dc couple function is remotely selected The offset voltage must be referenced to the External offset common pin 4 of the remote input connector It must be electrically isolated from the controlling system The following table shows the offset range and remote offset requirements for probe and adapter combinations Remote Offset Input Requirements Offset Range Remote Requirements Probe alone 20V 10V Probe with 10x adapter 20
65. stment Attenuator Adapter Adjustment Connect the adapter probe combination to the test board in the position shown in the figure below signal to both inputs EY xL O o Signal to both input Alternately adjust the LF CMRR and then the HF RESP for a minimum signal on the oscilloscope Repeat the adjustments until the signal is optimized to a minimum Each adjustment should be set to minimize the component of the signal it affects most Some high frequency components of the signal are not affected by either adjustment 52 Service 53 WARNING Service Introduction Introduction This section provides troubleshooting service and repair information for the 1141A Differential Probe and 1142A Probe Control and Power Module The troubleshooting information is provided to isolate a faulty assembly When a faulty assembly has been located the disassembly assembly procedures help direct replacement of the assembly Maintenance should be performed by trained service personnel aware of the hazards involved for example fire and electric shock When maintenance can be performed without power applied the power cord must be removed from the instrument 54 Service Performance Specifications and Characteristics Performance Specifications and Characteristics The following table gives performance specifications used to test the 1141A and 1142A It also gives performance characteristics that are
66. strument Recommended Test Equipment The following table is a list of the test equipment required to test calibration make adjustments and troubleshoot this instrument The table indicates the critical specifications of the test equipment and for which procedure the equipment is necessary Equipment other than the recommended model may be used if it satisfies the critical specifications listed in the table Recommended Test Equipment Recommended Agilent Equipment Required Critical Specifications Model Part Use Signal Generator to 200 MHz 400 m Vims 8648A P Function Generator 2 5 to 500 kHz 600 m Vp p to 16 Vp p 33120A A Oscilloscope gt 400 MHz bandwidth 1 mV div sensitivity 54830B dc source 100 mV to 7 E3632A P CAUTION Operating the Probe Recommended Test Equipment Equipment Required Critical Specifications Test Board No substitute supplied accessory Load BNC Feedthrough 50 Q Cables 2 BNC 50 36 inch Cable BNC 50 Q 9 inch Cable Type N m 24 inch Adapter Type N m to BNC f Adapter Type N f to BNC m Adapters 2 BNC f to dual banana m Alignment tool Small flat blade supplied accessory P Calibration Tests A Adjustments Setting up the probe Recommended Agilent Model Part 01141 66504 Pasternack Enterprises PE6008 50 or Huber Suhner 22543742 10503A 10502A 11500B 1250 0780 1250 0077 1251 2277 8710 1961 Sprague Goodman part number
67. tem Item numbers refer to the numbers in Figure 1 1 on page 7 and Figure 1 2 on page 8 Those without item numbers are supplied but not shown in figures See the Replaceable Parts List for parts not listed below Item Description Oty Part Number 1 Differential Probe 1 2 10x Attenuator Adapter 1 5063 2144 3 100x Attenuator 1 5063 2145 4 ac Coupling Adapter 1 5063 2146 5 Two inch Extension Leads package 5 1 5959 9334 6 Mini Grabbers 2 1400 1422 7 Five inch Ground Lead 1 5061 6162 8 Shielded Signal Lead 1 01141 68702 9 Test Board 1 01141 66504 10 Flat blade Alignment Tool 1 8710 1961 11 Circuit Connection Posts strip of 20 1 1251 5943 Probe Control and Power Module 1 1142A Power Cord 1 see parts list Carrying case User and Service Manual Operating the Probe Accessories Supplied Figure 1 1 1141A Differential Probe and Accessories Operating the Probe Accessories Available Figure 1 2 1141A Miscellaneous Accessories Figure 1 3 PROSE CONTROL POWER MODULE LOCAL Varlable m Local Coarse Fins On 1142A Probe Control and Power Module Accessories Available The following accessories can be ordered e 5959 9335 Long Extension Lead 5 5 inch 14 cm package of 5 e 5090 4833 Mini grabber for SMT package of 20 Operating the Probe To inspect the probe
68. the correct safety precautions are taken see the following warnings In addition note the external markings on the instrument that are described under Safety Symbols Warnings Before turning on the instrument you must connect the protective earth terminal of the instrument to the protective conductor of the mains power cord The mains plug shall only be inserted ina socket outlet provided with a protective earth contact You must not negate the protective action by using an extension cord power cable without a protective conductor grounding Grounding one conductor of a two conductor outlet is not sufficient protection Only fuses with the required rated current voltage and specified type normal blow time delay etc should be used Do not use repaired fuses or short circuited fuseholders To do so could cause shock or fire hazard If you energize this instrument by an auto transformer for voltage reduction or mains isolation the common terminal must be connected to the earth terminal of the power source Whenever it is likely that the ground protection is impaired you must make the instrument inoperative and secure it against any unintended operation Service instructions are for trained service personnel To avoid dangerous electric shock do not perform any service unless qualified to do so Do not attempt internal service or adjustment unless another person capable of rendering first
69. the two low frequency paths These adjustments affect the CMRR quality of the probe The inputs of the inverting op amps include protection for ESD and over voltage conditions The inverting op amps feed a precision differential amplifier with unity gain and a single ended output The output is fed to the summing amp and to the control module for use in the dc reject circuit Summing Amp The summing amp combines the feedback signal the low frequency signal and the offset signal The LOW FREQ GAIN adjustment matches the gain of the low frequency path to the overall gain Control and Power Module The control and power module provides offset functions local and remote control and power to the probe system 60 Figure 3 5 Service Theory of Operation Offset Functions There are two offset functions developed in the control module variable offset and dc reject A variable offset voltage with coarse and fine adjustments can be selected by the front panel controls The offset level is buffered by U8 and selected by multiplexer U3 as the input to offset amp U7 The output of the offset amp is summed with the low frequency signal and feedback which gives dc coupling in the probe Front panel screwdriver adjustment Offset Null zeros the dc output from the probe when the dc input and offset are zero For dc Reject an output from the low frequency amplifier in the probe LFSIG is used to develop a voltage used to null the dc component o
70. tion 5 to 500 Hz 10 Random vibration 5 to 500 Hz 10 min minutes per axis 0 3grms per axis 2 41 grams Resonant search 5 to 500 Hz swept sine 10ctave min sweep rate 0 75g 5 min resonant dwell at 4 resonances per axis Power Voltage 90 to 132 198 to 264 Vac 47 to 440 Hz Requirements Power 25 VA maximum Te ron nae 00000 Weight Net approximately 1 8 kg 4 0 Ib Shipping approximately 2 7 kg 6 0 Ib Dimensions Refer to the outline drawings below 77 mm 3 e 159 mm 6 65 4 227 mm 8 9 171 mm 745 1142A Probe Control and Power Module 1141A Differential Probe m m oticos mm 4 45 in 1584 mm 62 4 28 110 E 1076 mm 42 3 5 1 a 19 7 mm 130 5 12 gt ke 46 mm 18 in 0 78in Mechanical Dimensions Oft E07 58 Figure 3 4 Service Theory of Operation Theory of Operation The following discussion covers block level theory for the 1141 1142 differential probe system Refer to the block diagram below The differential probe system consists of two units the 1141A Differential Probe with its accessories and the 1142A Probe Control and Power
71. tions and Characteristics Figure 3 1 30000 1 1000 1 40 Hz 100 Hz 1 kHz 10 kHz 100 kHz 1 MHz 10 MHz 100 MHz 01141M01 FREQUENCY CMRR Specifications and Characteristics Legend A CMRR specification for probe with no input adapters Low frequency CMRR specification for probe with the ac adapter Typical CMRR characteristic for differential probe with no input adapters Typical CMRR characteristic for differential probe with 100x attenuator adapter input Typical CMRR characteristic for differential probe with 100x attenuator adapter input moo wp 56 Service Performance Specifications and Characteristics Figure 3 2 1000 100Hz 1KHz 10KHz 100KHz 1MHz 10MHz 100MHz 1GHz 2 Maximum Input Voltage vs Frequency Legend A Input voltage limits for probe alone B Input voltage limits for 10x adapter C Input voltage limits for 100x adapter 57 Figure 3 3 Service General Characteristics General Characteristics The following characteristics apply to the 1141A Differential Probe with the 1142A Probe Control and Power Module Environmental Conditions Operating Non operating Temperature 0 to 55 C 32 F to 131 F 40 C to 70 C 40 F to 158 F Humidity up to 95 relative humidity non up to 90 relative humidity at 65 C condensing at 40 C 104 F 149 F Altitude up to 4 600 meters 15 000 ft up to 15 300 meters 50 000 ft Vibration Random vibra
72. ts to the PC board Disconnect the cable connector from the probe PC board 66 Figure 3 8 Service Removing and Replacing Assemblies Reassemble Probe The ground screw passes through the top cover and PC board and screws into the ground block Ifreplacing the PC board remove the input connectors from the old board and put them on the new one If replacing the cable note the orientation of the probe clamp ring on the old cable remove the ring and put it on the new cable Connect the cable connector to the PC board Solder the two connections of the coaxial cable to the PC board On anew probe cable the conductors of the coaxial cable are connected by a heavy single wire Cut the heavy wire so it matches the wire on the cable that was removed Assemble the PC assembly into the top cover The large hybrid is exposed when the assembly is in the top cover The figure on the below shows the sequence of the ground screw top cover PC board and ground block Reassembling Probe Insert the input connectors first and seat the cable end of the PC assembly over the pins at the rear of the cover b Position the ground block at the front of the PC assembly Insert the grounding screw through the top cover and screw it into the ground block as shown in the figure above 6 Replace the bottom cover Position the cable strain relief and with one hand hold the cable and top cover together The f
73. ty Description Mfr Mfr Part Number Code Number RP1 1810 1242 RESISTOR NETWORK 28480 1810 1242 51 3101 2609 SWITCH SL DPST STD 250VAC PC 28480 13101 2609 52 3101 3007 1 SWITCH 6 STATION ASSEMBLY 28480 13101 3007 TI 9100 4750 1 TRANSFORMER POWER with mtg hardware 28480 19100 4750 U1 1826 1403 2 ICVRGLTER ADJ POS 3 40V 00000 LT317AT U2 1826 1670 2 IC V RGLTR ADJ NEG 37 1 2V 0 220 PKG 00000 LT337AT U3 5081 9233 1 ANALOG MULTIPLEXER 4 CHNL 16 DIP P 28480 1820 2182 U4 1826 1403 IC V RGLTR ADJ POS 3 40V 00000 LT317AT U5 1826 1670 IC V RGLTR ADJ NEG 37 1 2V 220 PKG 00000 LT337AT U6 1826 1381 3 AMP LOW BIAS H IMPD 8 DIP P PKG 00000 LT1012CN8 U7 1826 1381 IC OP AMP LOW BIAS H IMPD 8 DIP P PKG 00000 171012 8 08 1826 1381 OP LOW BIAS H IMPD 8 DIP P PKG 00000 171012 8 09 1820 3177 1 MUXR DATA SEL 05 74 2 TO 1 LINE 04713 MC74HC157N U10 1826 0774 1 IC V RGLTR V REF FXD 1 22 1 24V 92 27014 LM385BZ 1 2 U1 1826 0635 1 IC OP AMP LOW OFS 8 DIP P PKG 06665 07 1902 0951 1 DIODE ZNR 5 1V 5 00 35 PD 4W 035 28480 1902 0951 w1 01141 61602 1 CABLE ASSEMBLY SAFETY GROUND 28480 101141 61602 84 Service Replaceable Parts Locator Table for Control and Power Supply Ref Grid Ref Grid Ref Grid Ref Grid Ref Grid Ref Grid Ref
74. typical for the probe system Performance Specifications and Characteristics Parameter Probe alone With 10x attenuator With 100x attenuator SPECIFICATIONS Bandwidth 3 dB dc coupled dc to 200 MHz Rise Time calculated 1 75 ns Gain Accuracy 2 0 4 096 CMRR See the graphs in figure 3 Maximum Input Voltage 200 peak ac 500 peak see figure 3 2 Differential Input Range DC mode with no offset 300 mV peak 3 0 V peak 30 V peak with DC Reject or appropriate 20 Vdc decreasing to 200 Vdc decreasing to 500 Vdc decreasing to offset 300 mV at 30 Hz 3 0 mV at 30 Hz 30 mV at 30 Hz Common mode Operating Range 20 200 500 dc to 30 Hz linear change linear change linear change 30 Hz to 200 MHz 0 5 V 5 50 dc Offset Range 20V 200 V 500 V Input Impedance Resistance 1MQ 9 10 MQ Capacitance 7 pF 3 5 pF 2 pF ac Low freq Response 3dB 15 Hz 1 5 Hz 1 5 Hz dc Reject Response 5 Hz 0 5 Hz or 0 05 Hz selectable irrespective of attenuator Output Impedance 500 Thermal drift lt 50 uVdc C Displayed noises lt 50 UVims Overload Recovery lt 1 ms from overdrive that is less than the common mode range Note 1 For maximum signal fidelity above 100 MHz limit the probe input without attenuators to lt 300 mV peak to peak 55 Service Performance Specifica
75. urement from the bottom DVM in figure 2 2 Calculate the 10x attenuator gain as out AV V out out 2 X Vin Record the result of this calculation in the Calibration Test Record on page 39 Failure of the accuracy test for the 10x attenuator can be caused by mis adjustment of the low frequency CMRR LF CMRR adjustment Perform the Attenuator Adapter Adjustment procedure in the Adjustments section later in this chapter then retest the attenuator adapter If if continues to fail repair is necessary 31 Figure 2 6 CAUTION Calibration Tests and Adjustment dc Gain Accuracy 100x Attenuator Accuracy Test If the gain test for the probe fails it will be reflected in the test for the 100x attenuator adapter Do not continue until the probe passes the gain test Disconnect the probe attenuator from the test board Remove the 10x attenuator adapter from the probe and connect the 100x attenuator adapter Carefully connect the input of the probe attenuator to the test board in the position shown in the figure below signal to input LS Signal to input Avoid excessive power dissipation in the termination on the test board Keep the voltage input at or below 7 Vdc 3 Setthe dc source output to 7 Vdc 4 Record the V measurement from the top DVM in figure 2 2 5 Record measurement from the bottom DVM in figure 2 2 32 Figure 2 7 NOTE
76. ustment CMRR Test 7 oscilloscope press AUTOSCALE and set the following parameters Menu Selection Setting TIMEBASE time div 500 ns div CHAN 1 sensitivity 200 mV div input R 50 Q DC ACQUISITION Sampling Mode Real Time Memory Depth Automatic Sample Rate Automatic Averaging Enabled of avg 32 8 On oscilloscope measure the peak to peak voltage of the channel 1 signal then V P P then press 1 and record the reading Vp p __________ 9 Connect input of probe to test board in position shown in the figure below signal to both inputs 1 CU Signal to both input 10 Set the sensitivity to 1 mV div 11 After the measurement settles averaging is complete record the V P P reading Nop 12 Disconnect the probe amp from the test board and measure pp channel 1 13 Calculate the CMRR result as follows V CMRR DP Vioisepp 14 The result in step 12 should be 3000 representing a CMRR of 3000 1 or more Record the CMRR in the Calibration Test Record 37 Figure 2 11 Figure 2 12 15 16 17 18 19 20 21 22 23 24 Calibration Tests and Adjustment CMRR Test Connect the input of the probe to the test board in the position shown in the figure below signal to input Signal to input Set the signal generator for 100 MHz at 0 0 dBm about 22

1141A Differential Probe and 1142A Probe Control

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