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Service

4

Troubleshooting

1141A and 1142A User’s Guide

65

Troubleshooting

Use the following paragraphs to assist in troubleshooting problems
with the 1141A/1142A Differential Probe.

Probe Troubleshooting

To troubleshoot the probe:

1

Apply a known signal to the input of the probe.

2

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 twice the amplitude of the input signal.

3

If the signal is incorrect, check the power supply voltages from the
1142A Probe Control and Power Module. Use the cable diagram on
the next page.

4

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 locater, and schematics are provided
later in this chapter.

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Содержание 1141A

Страница 1: ...Agilent Technologies Agilent 1141A Differential Probe and 1142A Probe Control and Power Module User s Guide and Service Guide...

Страница 2: ...ncy regulation or contract clause Use duplication or disclo sure of Software is subject to Agilent Tech nologies standard commercial license terms and non DOD Departments and Agencies of the U S Gover...

Страница 3: ...ng Functions 21 Remote Operation 23 Differential Amplifiers and CMRR 25 2 Calibrating the Probe dc Gain Accuracy 29 10x Attenuator Accuracy Test 32 100x Attenuator Accuracy Test 34 Bandwidth 36 CMRR T...

Страница 4: ...4 1141A and 1142A User s Guide Contents...

Страница 5: ...probe system the 1141A Differential Probe and 1142A Probe Control and Power Module In this document the two models will be treated as a system Each of the two instrument models that make up the diffe...

Страница 6: ...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 prob...

Страница 7: ...enuator Adapter 1 5063 2144 10 Flat blade Alignment Tool 1 8710 1961 3 100x Attenuator 1 5063 2145 11 Circuit Connection Posts strip of 20 1 1251 5943 4 ac Coupling Adapter 1 5063 2146 Probe Control a...

Страница 8: ...e 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 If you...

Страница 9: ...54830B P A dc source 100 mV to 7 Vdc E3632A P Test Board No substitute supplied accessory 01141 66504 A Load BNC feed through 50 Pasternack Enterprises PE6008 50 or Huber Suhner 22543742 P Cables 2 B...

Страница 10: ...Grounding one conductor of a two conductor outlet is not sufficient protection WARNING Only fuses with the required rated current voltage and specified type normal blow time delay etc should be used D...

Страница 11: ...rement NOTE The 1141A 1142A probe system specifically the 1142A requires a power source of either 115 230 Vac 47 to 440 Hz 25 VA maximum CAUTION Before connecting power to this instrument be sure the...

Страница 12: ...a flat bladed screwdriver b While the fuse holder is pushed in gently turn the fuse holder counterclockwise 3 Connect the 1141A probe cable power connector to the 1142A s rear panel PROBE connector 4...

Страница 13: ...he range of adjustment is about 4 mV DC Reject Gain adjusts the gain of the dc reject circuit to accurately null the dc component of an input signal The range of adjustment is about 0 5 Figure 4 1142A...

Страница 14: ...adapter to the supply and connect a BNC cable between the supply and the test board 8 Warm up the 1141A for 30 minutes before making adjustments 9 With the 1141A probe inputs unconnected adjust Offse...

Страница 15: ...ny method used to connect to the probe signal inputs also applied to the adapters Figure 6 shows in a general way the use of accessories Figure 6 Basic Accessory Connections Probe Tips Probe tips fit...

Страница 16: ...arameters 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 Connect the leads at right angles to the circu...

Страница 17: ...ters There are three adapters for use with the differential probe Two adapters are attenuators a 10x and a100x The other is an ac adapter for blocking dc from the probe input The adapters are installe...

Страница 18: ...adapter is 9 M for the 10x adapter and 10 M for the 100x adapter Connector Compatibility The following are general connector characteristics for the probe adapters and accessories The female connector...

Страница 19: ...Operating the Probe 1 Using the Accessories 1141A and 1142A User s Guide 19 Figure 8 Allowed Adapter Connections...

Страница 20: ...This reduces the effectiveness of the differential probe The mechanical connections at the input of the probe are ground for probe signals The screw where the ground lead attaches fastens to this gro...

Страница 21: ...There is a selectable low frequency corner with 3dB points at 0 05 Hz 0 5 Hz or 5 0 Hz The voltage reject range is 20V with the probe alone 200V with the 10x attenuator and 500V with the 100x attenua...

Страница 22: ...ge rating rather than the operating range of the offset To use offset 1 Remove the ac adapter if it is installed 2 On the front panel of the 1142A press Local and Variable offset 3 Adjust the Coarse a...

Страница 23: ...rolled through the rear panel standard 9 pin female D sub miniature connector The following table gives the connections NOTE To minimize dc offset errors and potential noise coupling electrically isol...

Страница 24: ...must be electrically isolated from the controlling system The following table shows the offset range and remote offset requirements for probe and adapter combinations Table 4 Remote Functions Select...

Страница 25: ...s in the probe However 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 thi...

Страница 26: ...ndent 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 o...

Страница 27: ...ipment 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...

Страница 28: ...e The recommended test interval is yearly or every 2 000 hours of operation Amount of use environmental conditions and the user s experience concerning need for testing will contribute to verification...

Страница 29: ...A Probe Amp disconnected from the test PCA adjust the Offset Null control on the 1142A until the DVM reads 0 Vdc If the probe output voltage cannot be set to 0V subtract this voltage from the subseque...

Страница 30: ...output 100 mV nom 6 Record the Vin1 measurement from the top DVM in Figure 11 7 Record the Vout1 measurement from the bottom DVM in Figure 11 8 Connect the Probe Amp to measure a negative voltage as...

Страница 31: ...of this calculation in the Calibration Test Record on page 42 To pass this test the probe gain 0 98 to 1 02 NOTE Failure of the gain accuracy test can be caused by mis adjustment of the probe Perform...

Страница 32: ...e probe 2 Carefully connect the input of the probe attenuator to the test board in the position shown in Figure 13 Figure 13 Signal to Input 3 Set the dc calibrator output 3V dc 4 Record the Vin1 meas...

Страница 33: ...on page 42 NOTE 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...

Страница 34: ...attenuator adapter 2 Carefully connect the input of the probe attenuator to the test board in the position shown in Figure 15 Figure 15 Signal to Input CAUTION Avoid excessive power dissipation in th...

Страница 35: ...result of this calculation in the Calibration Test Record on page 42 NOTE Failure of the accuracy test for the 100x attenuator can be caused by mis adjustment of the low frequency CMRR LF CMRR adjustm...

Страница 36: ...ut 2 Set the signal generator for 200 MHz at 0 dBm about 224 mVrms 3 Set the 1142A front panel switches to Local and Zero offset 4 On the oscilloscope press AUTOSCALE then set the parameters listed in...

Страница 37: ...n the position shown in Figure 17 Figure 17 Signal to Input 7 Record the Vp p reading on the oscilloscope Vp p 1 _____________ mV 8 Divide the reading from step 7 by the reading from step 5 9 Record t...

Страница 38: ...1 input 4 Connect the input of the probe to the test board in the position shown in the Figure 18 Figure 18 Signal to Input 5 Connect the signal generator to the test board 6 Set the signal generator...

Страница 39: ...nputs 10 Set the sensitivity to 1 mV div 11 After the measurement settles averaging is complete record the V P P reading Vp p 2 _____________ mV 12 Disconnect the probe amp from the test board and mea...

Страница 40: ...224 mVrms 632 mVp p 17 Set the oscilloscope to channel 1 and change the horizontal scale to 5 ns div 18 After the measurement settles averaging is complete note the V P P reading Vp p 1 _____________...

Страница 41: ...2 CMRR Test 1141A and 1142A User s Guide 41 24 Record the result of this calculation in the Calibration Test Record on page 42 The result in step 21 should be 10 representing a CMRR of 10 1 or more CM...

Страница 42: ...______________________________ Work Order No ____________________ Recommended Test Interval 1 Year 2000 hours Date____________________ Recommended next testing_________________ Temperature____________...

Страница 43: ...ns specified at the beginning of the respective procedures NOTE Warm up the instrument for 30 minutes before starting adjustment procedures Equipment Required A complete list of equipment required for...

Страница 44: ...can be connected to the test board in one of three ways as shown in the top row of Figure 22 The bottom row in the figure shows the position of the probe s A1 PC assembly on the test board At each po...

Страница 45: ...and mechanically vulnerable CAUTION Do these adjustment procedures in an ESD safe area CAUTION Avoid inadvertent contact between the powered assembly and nearby tools and equipment CAUTION Avoid mecha...

Страница 46: ...NOTE Note the position of the ground block at the input end of the probe The ground block is held through the A1 PC assembly by the grounding screw on the top of the probe The ground block must be re...

Страница 47: ...NC cables to connect the function generator to the oscilloscope Connect the generator OUTPUT to oscilloscope channel 1 input and the generator TRIG OUTPUT to the oscilloscope EXT TRIG 12 On the oscill...

Страница 48: ...MRR as shown in Figure 25 on page 48 Figure 25 R11 HF CMRR Adjustment 18 Adjust R9 HF GAIN so the Vp p 1 measurement is the same as in step 4 within 0 5 Make the adjustment slowly so the oscilloscope...

Страница 49: ...restart averaging Step 3 Adjust the 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 l...

Страница 50: ...ain and C4 LF BANDWIDTH for the flattest pulse top see Figure 28 on page 50 Again adjust slowly and press CLEAR DISPLAY frequently to restart averaging Figure 28 R14 and C4 Adjustment 27 Carefully con...

Страница 51: ...he probe meets all specifications except bandwidth Adjust R13 for unity gain at 200 MHz 31 Connect the signal generator to the test board and set it for 200 MHz and 300mVp p 107 mVrms 32 Carefully con...

Страница 52: ...connect the probe power cable at the rear panel of the 1142A 36 Remove the probe PC assembly from the test board Be sure the probe input connectors remain attached to the probe 37 Remove the grounding...

Страница 53: ...he bottom cover a Position the cable strain relief and with one hand hold the cable and top together NOTE The flange on the strain relief has a notch that fits around a protrusion in the top cover CAU...

Страница 54: ...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 substra...

Страница 55: ...board The short cable minimized ground loop voltages 4 Set the function generator for a 3 5 kHz square wave with the following amplitude Amplitude for 10x adapter 3 0 Vp p Amplitude for 100x adapter 1...

Страница 56: ...e HF RESP for best overall pulse response the flattest pulse top Use the figure below for adjust locations Figure 33 Adjustment Locations Table 16 Oscilloscope Settings Menu Selection Setting TIMEBASE...

Страница 57: ...adapter probe combination to the test board in the position shown in Figure 34 Figure 34 Signal to Both Input 12 Alternately adjust the LF CMRR and then the HF RESP for a minimum signal on the oscillo...

Страница 58: ...58 1141A and 1142A User s Guide 3 Adjusting the Probe Attenuator Adapter Adjustment...

Страница 59: ...nt of the assembly For complex parts the service policy is for assembly level repair For parts with simple circuitry the service policy is component level repair The service policy for the 1141A is as...

Страница 60: ...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...

Страница 61: ...ion 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 combine...

Страница 62: ...de 4 Service Theory of Operation Figure 35 1141A Differential Probe System Block Diagram 1142A Control and Power Module The control and power module provides offset functions local and remote control...

Страница 63: ...ff 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 cancellat...

Страница 64: ...Attenuator Adapter Simplified Schematic 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...

Страница 65: ...utput cable is not terminated or the coax is open the output signal will be about twice the amplitude of the input signal 3 If the signal is incorrect check the power supply voltages from the 1142A Pr...

Страница 66: ...66 1141A and 1142A User s Guide 4 Service Troubleshooting Figure 38 1142A Probe Control and Power Module...

Страница 67: ...embled If unsupported the weight of the cable can put strain on the PC board 2 Loosen the probe clamp ring at the cable end of the probe 1 4 turn counter clockwise and slide it down the cable 3 Remove...

Страница 68: ...g and put it on the new cable 3 Connect the cable connector to the PC board 4 Solder the two connections of the coaxial cable to the PC board On a new probe cable the conductors of the coaxial cable a...

Страница 69: ...en with the probe clamp ring If the covers do not fit together tightly and easily check for pinched wires see caution above To Disassemble the Probe Adapters Use the following procedure to disassemble...

Страница 70: ...ssembling the adapter is slightly harder because you have to align the connector pins and thumb wheel screw while sliding the inner housing and outer housing together 1 Be sure the input connectors an...

Страница 71: ...edure to disassemble the probe control and power module WARNING Hazardous voltages exist on the power supply To avoid electrical shock adhere closely to the following procedures 1 Remove the power cor...

Страница 72: ...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...

Страница 73: ...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 Table 17 Manufacturers Code List Mfr No Nam...

Страница 74: ...74 1141A and 1142A User s Guide 4 Service Replaceable Parts Figure 42 1141A Differential Probe Parts Identification...

Страница 75: ...Service 4 Replaceable Parts 1141A and 1142A User s Guide 75 Figure 43 Power and Control Board Component Identification...

Страница 76: ...76 1141A and 1142A User s Guide 4 Service Replaceable Parts Figure 44 Cabling Diagram...

Страница 77: ...4 Replaceable Parts 1141A and 1142A User s Guide 77 Figure 45 1142A Probe Control and Power Module IC Connectors not Shown Supply Pin No IC Group 15 14 U3 15 3 GND 15 15 7 U6 8 11 15 4 NC 1 5 8 5 16 U...

Страница 78: ...78 1141A and 1142A User s Guide 4 Service Replaceable Parts Figure 46 1142A Probe Control and Power Module...

Страница 79: ...E LABEL 28480 01141 94301 W1 01141 61603 1 PROBE CABLE ASSEMBLY 28480 01141 61601 10X Attenuator Adapter 01141 26102 2 PROBING PIN 28480 01141 26102 01141 24102 2 CAP PROBING PIN 28480 01141 24101 100...

Страница 80: ...28480 0340 1097 MP5 0403 1012 4 FOOT 28480 0403 0727 MP6 5041 0234 5 KEYCAP 28480 5041 0234 W1 8120 1521 1 POWER CORD 18 AWG 3 COND 90 IN LG US Canada only 28480 8120 1521 Table 18 1141A and 1142A Rep...

Страница 81: ...OR FXD 4 7UF 10 35VDC TA 28480 0180 3845 C11 NOT ASSIGNED C12 0160 5581 1 CAPACITOR FXD 0 033UF 10 63VDC 28480 0160 5581 C13 0160 6190 CAPACITOR FXD 0 33UF 10 50VDC 28480 0160 6190 C14 0160 7060 1 CAP...

Страница 82: ...HOLDER 6 3A 250A 28480 2110 0642 E2 2110 0565 1 FUSEHOLDER CAP 28480 2110 0565 F1 2110 0201 1 FUSE 0 25A 250V TD 28480 2110 0201 H1 0515 1579 1 SCREW MACHINE M5 18mm LG 28480 0515 1579 HS1 01142 21101...

Страница 83: ...F TC 0 25 28480 0698 6317 R17 0698 4002 RESISTOR 5K 1 0 125W TF TC 0 100 24546 CT4 1 8 TO 5001 F R18 0699 1203 RESISTOR 120 0 1 0 125W TF TC 0 25 28480 0699 1203 R19 0698 6317 RESISTOR 500 0 1 0 125W...

Страница 84: ...80 3101 3007 T1 9100 4750 1 TRANSFORMER POWER with mtg hardware 28480 9100 4750 U1 1826 1403 2 IC V RGLTER ADJ POS 3 40V 00000 LT317AT U2 1826 1670 2 IC V RGLTR ADJ NEG 37 1 2V TO 220 PKG 00000 LT337A...

Страница 85: ...B 5 CR13 C 3 R8 C 5 R25 B 2 R48 D 3 U8 B 3 C5 C 3 C21 B 5 CR14 C 6 MP1 H 1 R9 C 4 R26 B 2 U9 A 5 C6 C 5 C22 B 6 CR17 B 5 MP2 E 3 R10 C 5 R27 A 5 RP1 B 3 U10 C 2 C7 B 3 C23 B 4 CR18 B 6 MP3 D 3 R11 C 5...

Страница 86: ...86 1141A and 1142A User s Guide 4 Service Replaceable Parts...

Страница 87: ...robe connectors 18 circuit connector posts 16 cleaning instrument 8 CMRR definition 25 high frequency gain 47 low frequency response 49 test 38 common mode rejection ratio 25 compensating dc 21 connec...

Страница 88: ...tion 23 remote offset input 24 remote operation 23 removing assemblies 67 replaceable parts 72 replacing assemblies 67 S schematic probe power module 66 77 probe control power module 78 service policy...

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