Agilent Technologies 1141A User'S Manual And Service Manual Download Page 20 | Manualshive

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1141A and 1142A User’s Guide

1

Operating the Probe

Grounding

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 screw where the ground lead attaches fastens to this ground.
See

. 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.

Figure 9

Probe Grounds

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Summary of Contents for 1141A

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

Page 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...

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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 _____________...

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

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

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

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

Page 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...

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

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

Page 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...

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

Page 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...

Page 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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