Keithley 2000 Repair Manual
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Keithley 2000 Repair Manual

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Model 2000
Multimeter
Repair Manual
A G R E A T E R M E A S U R E O F C O N F I D E N C E

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  • Page 1 Model 2000 Multimeter Repair Manual A G R E A T E R M E A S U R E O F C O N F I D E N C E...
  • Page 2 WARRANTY Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 3 years from date of shipment. Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries, diskettes, and documentation.
  • Page 3 Model 2000 Multimeter Repair Manual ©1995, Keithley Instruments, Inc. All rights reserved. Cleveland, Ohio, U.S.A. Second Printing, March 1997 Document Number: 2000-902-01 Rev. B...
  • Page 4 Revision of the manual. Each new Revision includes a revised copy of this print history page. Revision A (Document Number 2000-902-01) ..............May 1995 Revision B (Document Number 2000-902-01) .............. March 1997 All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
  • Page 5 afety Precautions The following safety precautions should be observed before using this product and any associated instrumentation. Although some instruments and accessories would normally be used with non-hazardous voltages, there are situations where hazardous conditions may be present. This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury.
  • Page 6 bles or jumpers, installing or removing switching cards, or making internal changes, such as installing or removing jumpers. Do not touch any object that could provide a current path to the common side of the circuit under test or power line (earth) ground. Al- ways make measurements with dry hands while standing on a dry, insulated surface capable of withstanding the voltage being measured.

  • Page 7: Table Of Contents

    Table of Contents Routine Maintenance Introduction..................1-2 Setting line voltage and replacing fuse ..........1-2 AMPS fuse replacement ..............1-4 Troubleshooting Introduction..................2-2 Repair considerations................2-3 Power-on test ..................2-3 Front panel tests...................2-4 Principles of operation.................2-5 Display board checks.................2-11 Power supply checks................2-11 Digital circuitry checks..............2-12 Analog signal switching states............2-13 Built-In Test overview ...............2-18 Built-In Test documentation ..............2-22 Disassembly...
  • Page 8 List of Illustrations Routine Maintenance Power module..................1-3 Troubleshooting Power supply block diagram ............... 2-6 Digital circuitry block diagram ............2-7 Analog circuitry block diagram............2-9 Disassembly Trigger link line connections............... 3-6...
  • Page 9 List of Tables Routine Maintenance Fuse rating ...................1-3 Troubleshooting Power supply circuits................2-7 Display board checks.................2-11 Power supply checks................2-11 Digital circuitry checks..............2-12 DCV signal switching................2-13 ACV and FREQ signal switching ............2-13 Ω2 signal switching ................2-14 Ω4 signal switching ................2-14 Ω2/Ω4 reference switching..............2-15 DCA signal switching................2-15 ACA signal switching ................2-15 DCV signal multiplexing and gain ............2-16...
  • Page 10 Routine Maintenance...

  • Page 11: Routine Maintenance

    Routine Maintenance Introduction The information in this section deals with routine type maintenance that can be performed by the operator. This information is arranged as follows: • Setting line voltage and replacing fuse — Explains how to select the alternate power line voltage setting, and how to replace a blown power line fuse.

  • Page 12: Routine Maintenance

    Routine Maintenance Figure 1-2 Model 2000 Power module WARNING: WARNING: NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY. NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY. MADE IN U.S.A. IEEE-488 (CHANGE IEEE ADDRESS 1000V FROM FRONT PANEL) 350V...

  • Page 13: Amps Fuse Replacement

    Routine Maintenance AMPS fuse replacement WARNING Make sure the instrument is disconnected from the power line and other equipment before replacing the AMPS fuse. Turn off the power and disconnect the power line and test leads. From the front panel, gently push in the AMPS jack with your thumb and rotate the fuse carrier one-quarter turn counter-clockwise.

  • Page 14: Troubleshooting

    Troubleshooting...

  • Page 15: Introduction

    This section of the manual will assist you in troubleshooting the Model 2000. Included are self-tests, test procedures, troubleshooting tables, and circuit descriptions. It is left to the discre- tion of the repair technician to select the appropriate tests and documentation needed to trouble- shoot the instrument.

  • Page 16: Repair Considerations

    Troubleshooting Repair considerations Before making any repairs to the Model 2000, be sure to read the following considerations. CAUTION The PC-boards are built using surface mount techniques and require special- ized equipment and skills for repair. If you are not equipped and/or qualified, it is strongly recommended that you send the unit back to the factory for re- pairs or limit repairs to the PC-board replacement level.

  • Page 17: Front Panel Tests

    Troubleshooting Front panel tests There are two front panel tests: one to test the functionality of the front panel keys and one to test the display. In the event of a test failure, refer to “Display Board Checks” for details on trou- bleshooting the display board.

  • Page 18: Principles Of Operation

    Troubleshooting Principles of operation The following information is provided to support the troubleshooting tests and procedures covered in this section of the manual. Refer to the following block diagrams: Block Diagrams: Figure 2-1 — Power supply block diagram Figure 2-2 — Digital circuitry block diagram Figure 2-3 —...

  • Page 19: Power Supply Block Diagram

    Troubleshooting Key matrix The front panel keys (S401-S430) are organized into a row-column matrix to minimize the number of microcontroller peripheral lines required to read the keyboard. A key is read by strob- ing the columns and reading all rows for each strobed column. Key down data is interpreted by the display microcontroller and sent back to the main microprocessor using proprietary encod- ing schemes.

  • Page 20: Digital Circuitry Block Diagram

    Troubleshooting Table 2-1 Power supply circuits Supply Rectifier Filter Regulator +5VD CR104 C128, C156 U144 +37V CR116, CR117 C104, C108 U101 +15V CR102 C148 U125 -15V CR102 C131 U119 +5V, +5VRL CR103 C146 U124 Digital circuitry Refer to Figure 2-2 for the following discussion on digital circuitry. Figure 2-2 Digital circuitry NVRAM...
  • Page 21 Troubleshooting Microprocessor U135 is a 68306 microprocessor that oversees all operating aspects of the instrument. The MPU has a 16-bit data bus and provides an 18-bit address bus. It also has parallel and serial ports for controlling various circuits. For example, the RXDA, TXDA, RXDB and TXDB lines are used for the RS-232 interface.

  • Page 22: Analog Circuitry Block Diagram

    Troubleshooting Analog circuitry Refer to Figure 2-3 for the following discussion on analog circuitry. Figure 2-3 AMPS Analog circuitry Current block diagram Shunts K103, R158, R205 AC Switching & Gain K102, U102, U103, U105, U112, U118, U111, U110 ACV, FREQ DCV &...
  • Page 23 2-10 Troubleshooting Signal switching Signal switching for DCV and OHMS is done by the DCV & Ohms Switching circuit. FETs Q113, Q105, Q104 and Q108 connect the DCV or ohms signal to the ×1 buffer (U113). (Tables 2-5 through 2-8 show the switching states of these FETs for the various DCV and OHMS ranges.) Note that the reference current for OHMS is generated by the Ohms I-Source circuit.

  • Page 24: Display Board Checks

    Troubleshooting 2-11 Display board checks If the front panel DISP test indicates that there is a problem on the display board, use Table 2-2. See “Principles of Operation” for display circuit theory. Table 2-2 Display board checks Step Item/component Required condition Remarks Front panel DISP test.

  • Page 25: Digital Circuitry Checks

    2-12 Troubleshooting Digital circuitry checks Digital circuit problems can be checked out using Table 2-4. See “Principles of Operation” for digital circuit. Table 2-4 Digital circuitry checks Step Item/component Required condition Remarks Power-on test RAM OK, ROM OK. Verify that RAM and ROM are functional.

  • Page 26: Analog Signal Switching States

    Troubleshooting 2-13 Analog signal switching states Tables 2-5 through 2-11 provide switching states of the various relays, FETs and analog switches for the basic measurement functions and ranges. These tables can be used to assist in tracing an analog signal from the input to the A/D multiplexer. Table 2-5 DCV signal switching Range...

  • Page 27: Ω2 Signal Switching

    2-14 Troubleshooting Table 2-7 Ω 2 signal switching Range Q101 Q102 Q114 Q136 Q109 K101* K102* Q113 Q105 Q104 Q108 Q121 100Ω RESET 1kΩ RESET 10kΩ RESET 100kΩ RESET 1MΩ RESET 10MΩ RESET 100MΩ RESET *K101 set states: Pin 8 switched to Pin 7 Pin 3 switched to Pin 4 K102 reset states: Pin 8 switched to Pin 9 Pin 3 switched to Pin 2...

  • Page 28: Troubleshooting

    Troubleshooting 2-15 Table 2-9 Ω 2/ Ω 4 reference switching U133 U133 Range Q123 Q125 Q124 Q126 Q120 /.7V 100Ω 1kΩ 10kΩ 100kΩ 1MΩ 10MΩ 100MΩ Table 2-10 DCA signal switching Range K103 10mA 100mA Table 2-11 ACA signal switching U105 U105 U111...

  • Page 29: Troubleshooting

    2-16 Troubleshooting Table 2-12 DCV signal multiplexing and gain Signal U129 U129 U129 Gain Range (U163) pin 1 pin 8 pin 9 (U166) ×100 100mV ×10 ×1 ×10 100V ×1 1000V Table 2-13 ACV and ACA signal multiplexing and gain Signal U129 U129...

  • Page 30: Ω4 Signal Multiplexing And Gain

    Troubleshooting 2-17 Table 2-16 Ω 4 signal multiplexing and gain Signal U129 U129 U129 Gain Range (U163) pin 1 pin 8 pin 9 (U166) ×100 100Ω S4 then S7 ×10 1kΩ S4 then S7 ×10 10kΩ S4 then S7 ×10 100kΩ...

  • Page 31: Built-In Test Overview

    2-18 Troubleshooting Built-In Test overview Built-In Test is used to test and exercise various circuits and components. The Built-In Tests are listed in Table 2-18. Many of the tests are actual pass/fail type tests, while others are circuit exercises that are used for subsequent tests. Each Built-In Test can be run manually. After a test is manually run, operation is “frozen”...

  • Page 32: Built-In Test Summary

    Troubleshooting 2-19 Table 2-18 Built-In Test summary Test Circuit tested Bank 100 100.1 100.2 101.1 TestCal 101.2 TestCal 101.3 TestCal Bank 200 REF/MUX 200.1 Reference 200.2 Reference 201.1 A/D Mux Lo 201.2 A/D Mux Lo Bank 300 DC/OHM 300.1 Front End Lo 301.1 Hi Ohms 301.2...
  • Page 33 2-20 Troubleshooting AUTO testing Press SHIFT and then TEST to access the self-test options. Use the key to display “TEST: BUILT-IN” and press ENTER. Use the key to display “BIT: AUTO” and press ENTER. Use the key to display the bank of tests that you wish to run and press ENTER.
  • Page 34 Troubleshooting 2-21 MANUAL testing Press SHIFT and then TEST to access the self-test options. Use the key to display “TEST: BUILT-IN” and press ENTER. Use the key to display “BIT: MANUAL” and press ENTER. Use the keys, or the keys to display the desired test series number. For example, if you wish to run test 302.2, display the series 302 test number as shown: MANUAL: 302 With the desired test series number displayed, press ENTER.

  • Page 35: Built-In Test Documentation

    • Input Requirements — Indicates the required state of the input terminals for the test. Note that input requirements are displayed by the Model 2000 when Built-In Test is run. • Expected Value and Limits — Provides the measurement or reading value (and limits) that is expected for the test as explained in the “Description”.
  • Page 36 Troubleshooting 2-23 TEST BANK: A/D Test 100.1 — A/D Bank Inputs Open Expected Value 153661550 counts Limits 1200000 counts Fault Message NO A/D COMM Description This A/D test uses the default conditions of the ADC word and the ACDC word. This sets up the front end of the instrument to a stable configuration. The MUX word is applied to register U130 which sets lines A0, A1 and A2 of U163 high.
  • Page 37 2-24 Troubleshooting Test 100.2 — A/D Bank Inputs Open Expected Value <none specified> Limits 100 counts Fault Message SIGNAL NOISY Description This test has the identical setup as the 100.1 test. Signal LO is connected to the A/D circuit for ten readings and a min/max comparison is done to en- sure that all readings are within 100 counts of each other.
  • Page 38 Troubleshooting 2-25 Test 101.1 — TESTCAL Bank Expected Value <none specified> Limits <none specified> Inputs Open Description TESTCAL is a way to calibrate the unit with internal references so that the remaining tests can be displayed in the form of voltages. Given that there are errors in the internal references and in the A/D circuitry, the voltages on the display of the unit may vary from the value that is measured at A/D-IN with a calibrated test meter.
  • Page 39 2-26 Troubleshooting Test 101.2 — TESTCAL Bank Inputs Open Expected Value (101.2) - (101.1) = 76275970 counts Limits 1800000 Fault Message NO 7V AT A/D Description This A/D test uses the default conditions of the ADC word and the ACDC word.
  • Page 40 Troubleshooting 2-27 Test 101.3 — TESTCAL Bank Inputs Open Expected Value 1.03 volts Limits 0.06 volts Fault Message NO 1V AT A/D Description This test uses the default conditions of the ADC word and the ACDC word. This sets up the front end of the instrument to a stable configuration. The MUX word sets shift register U130 to disable U163 by setting line /EN low.
  • Page 41 2-28 Troubleshooting TEST BANK: REF/MUX Test 200.1 — REFERENCE Bank REF/MUX Inputs Open Expected Value 1 volt Limits 0.1 volts Fault Message 1VREF/AD X10 Description The 7V REFHI signal is routed through R189 and R185, which forms a 0.014/1 voltage divider with R188. The 0.1V result (0.014 × 7V = 0.1V) is then applied to S1 of U163.
  • Page 42 Troubleshooting 2-29 Test 200.2 — REFERENCE Bank REF/MUX Inputs Open Expected Value 10 volts Limits 1 volt Fault Message AD X100 Same as test 200.1 except the A/D MUX is configured for ×100 gain (/ Description ×100 control line is low). The gain path is through U129 pin 10 to 11. Resis- tor network R271 is used to configure the x100 gain.
  • Page 43 2-30 Troubleshooting Test 201.1 — A/D MUX LO Bank REF/MUX Inputs Open Expected Value 0 volts Limits 0.0001 volts Fault Message SENSE LO 0 Description Signal LO is routed through R181 and Q122 (/LOMUXA control line high) into unity gain amp U126. Signal LO is then routed to S7 of U163. The A0, A1 and A2 bit pattern on U163 connects S7 to the D output, which then routes signal LO through Q117 to U166.
  • Page 44 Troubleshooting 2-31 Test 201.2 — A/D MUX LO Bank REF/MUX Inputs Open Expected Value 0 volts Limits 0.0001 volts Fault Message MUX LO Description This test is similar to test 201.1, except signal LO is routed through R274 to S8 of U163. Signal LO is then routed through Q117 to U166, which is con- figured for ×1 gain.
  • Page 45 2-32 Troubleshooting TEST BANK: DC/OHM Test 300.1 — FRONT END LO Bank DC/OHM Inputs Open Expected Value 0 volts Limits 0.01 volts Fault Message FRONT END LO Description This test is for the DC volts front end LO path. Control line DIVLO is high making the U120 comparator output (pin 2) open collector.
  • Page 46 Troubleshooting 2-33 Test 301.1 — HI OHMS Bank DC/OHM Inputs Open Expected Value 7 volts Limits 0.7 volts Fault Message 7V REFBOOT Description +7V is generated by buffering REFHI with op amp U139. This +7V, which is used by the ohms circuit as a voltage reference, is switched by U133 (/7V control line low) to op amp U123 which is a unity gain buffer.
  • Page 47 2-34 Troubleshooting Test 301.2 — HI OHMS Bank DC/OHM Inputs Open Expected Value 12.4 volts Limits 0.5 volts Fault Message 13.3 REFBOOT Description This test is the same as 301.1 except that the +13.3V ohms reference is tested. The +13.3V reference is generated by the same circuit as the +7V ref- erence.
  • Page 48 Troubleshooting 2-35 Test 302.1 — 2W SENSE Bank DC/OHM Inputs Open Expected Value 7 volts Limits 0.7 volts Fault Message 2W SENSE 7V Description The +7V reference is again switched to REFBOOT, and routed through R272, Q109, the 9.9MΩ half of divider R117, the parallel combination of R115, R324 and L109, and then through R113, R107, R103, R108, and K101.
  • Page 49 2-36 Troubleshooting Test 302.2 — 2W SENSE Bank DC/OHM Inputs Open Expected Value 12.4 volts Limits 0.5 volts Fault Message 2W SENSE 13V Description Same as test 302.1 except the +13.3V reference is used. This voltage does not go through the ohms zener clamp path but is clipped by the A/D circuit itself at about 12.4V due to the fact that 13.3V approaches the power supply limits of the op amps.
  • Page 50 Troubleshooting 2-37 Test 303.1 — LO OHM PATH Bank DC/OHM Inputs Open Expected Value 7 volts Limits 0.7 volts Fault Message 7V SOURCE Description This test uses the ohms circuit. The +7V reference is switched to REF- BOOT by closing U133 (/7V line low). Q123 and Q125 are turned on by set- ting the OHMA control line high.
  • Page 51 2-38 Troubleshooting Test 303.2 — LO OHM PATH Bank DC/OHM Inputs Open Expected Value 12.4 volts Limits 0.5 volts Fault Message 13.3V SOURCE Description This test is similar to test 303.1. The +13.3V reference is switched to REF- BOOT again by closing U133 pins 6 to 7. Q124 and Q126 are turned on by setting the OHMA control line low.
  • Page 52 Troubleshooting 2-39 Test 304.1 — INPUT /100 Bank DC/OHM Inputs Open Expected Value 7 volts Limits 0.7 volts Fault Message INP SIG/100 Description The ohms circuit current is set up the same as test 303.1. A 1mA current flows into the OHM node but instead of flowing into the clamping circuit, it flows through K101 (RESETK2 control line high) through Q102, Q101, R117, and Q114 to LO.
  • Page 53 2-40 Troubleshooting TEST BANK: VAC Test 400.1 — NON INV PATH Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This test places the ACV front end in the non-inverting configuration. Logic levels for this configuration are as follows: K102: /SETK1 low, /RESETK1 high U103: Pins 8 and 9 low U105: Pin 9 high...
  • Page 54 Troubleshooting 2-41 Test 400.2 — NON INV PATH Bank Inputs Open Expected Value 5.6 volts Limits 0.6 volts Fault Message NON INV PATH Description The previous test sets up the circuit for this test. There is a routine in soft- ware that generates a waveform for the ACV tests.
  • Page 55 2-42 Troubleshooting Test 400.3 — NON INV PATH Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This phase resets the circuit to a known state and turns the waveform sig- nal off. Subsequent tests require that the A/D be in the normal operating mode.
  • Page 56 Troubleshooting 2-43 Test 401.1 — INVERT PATH Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This test places the ACV front end in the inverting configuration. Logic levels for this configuration are as follows: K102: /SETK1 high, /RESETK1 low U103: Pins 8 and 9 high U105: Pin 9 low...
  • Page 57 2-44 Troubleshooting Test 401.2 — INVERT PATH Bank Inputs Open Expected Value 0.108 volts Limits 0.02 volts Fault Message INVERT PATH Description The previous test sets up the circuit for this test. There is a routine in soft- ware that generates a waveform for the ACV tests. This is done by selecting the 13.3V reference by closing analog switch U133 (/.7V control line low).
  • Page 58 Troubleshooting 2-45 Test 401.3 — INVERT PATH Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This phase resets the circuit to a known state and turns the waveform sig- nal off. Subsequent tests require that the A/D be in the normal operating mode.
  • Page 59 2-46 Troubleshooting Test 402.1 — NON INV /10 Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This test places the ACV front end in the non-inverting configuration. Logic levels for this configuration are as follows: K102: /SETK1 low, /RESETK1 high U103: Pins 8 and 9 low U105: Pin 9 high...
  • Page 60 Troubleshooting 2-47 Test 402.2 — NON INV /10 Bank Inputs Open Expected Value 0.108 volts Limits 0.02 volts Fault Message NON INV /10 Description The previous test sets up the circuit for this test. There is a routine in soft- ware that generates a waveform for the ACV tests.
  • Page 61 2-48 Troubleshooting Test 402.3 — NON INV /10 Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This phase resets the circuit to a known state and turns the waveform sig- nal off. Subsequent tests require that the A/D be in the normal operating mode.
  • Page 62 Troubleshooting 2-49 Test 403.1 — NON INV BEX2 Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This test places the ACV front end in the non-inverting configuration. Logic levels for this configuration are as follows: K102: /SETK1 low, /RESETK1 high U103: Pins 8 and 9 low U105: Pin 9 high...
  • Page 63 2-50 Troubleshooting Test 403.2 — NON INV BEX2 Bank Inputs Open Expected Value 1.08 volts Limits? 0.2 volts Fault Message NON INV BEX2 Description The previous test sets up the circuit for this test. There is a routine in soft- ware that generates a waveform for the ACV tests.
  • Page 64 Troubleshooting 2-51 Test 403.3 — NON INV BEX2 Bank Inputs Open Expected Value <none specified> Limits <none specified> Fault Message <none> Description This phase resets the circuit to a known state and turns the waveform sig- nal off. Subsequent tests require that the A/D be in the normal operating mode.
  • Page 65 2-52 Troubleshooting TEST BANK: SENSE Test 500.1 — 4W SENSE Bank SENSE Inputs 4-wire short Expected Value 0 volts Limits 0.0001 volts Fault Message SENSE LO Description This test requires a 4-wire short at the input. The SLO node is the Sense LO jack on the front or rear panel.
  • Page 66 Troubleshooting 2-53 Test 500.2 — 4W SENSE Bank SENSE Inputs 4-wire short Expected Value 0 volts Limits 0.0001 volts Fault Message SENSE HI Description This test requires a 4-wire short at the input. The SHI node is the Sense HI jack on the front or rear panel.
  • Page 67 2-54 Troubleshooting TEST BANK: AMP/OHM Test 600.1 — OHM/AMP Bank AMP/OHM Inputs INPUT HI to AMPS Short Expected Value 0.0095 volts Limits 0.001 volts Fault Message 1mA SOURCE Description This test requires a jumper wire from the INPUT HI jack to the AMPS jack on the front panel.
  • Page 68 Troubleshooting 2-55 Test 600.2 — OHM/AMP Bank AMP/OHM Inputs INPUT HI to AMPS short Expected Value 0.025 volts Limits 0.015 volts Fault Message .1 OHM SHUNT Description This test requires a jumper wire from the INPUT HI jack to the AMPS jack on the front panel.
  • Page 69 2-56 Troubleshooting Test 601.1 — AMP SHUNT Bank AMP/OHM Inputs INPUT HI to AMPS short Expected Value <none specified> Limits <none specified> Fault Message <none> Description This test requires an external jumper wire be installed from the INPUT HI jack to the AMPS jack on the front panel. There is a routine in software that generates a test signal current for the ACV AMP test.
  • Page 70 Troubleshooting 2-57 Bit patterns Bit pattern Register 87654321 87654321 87654321 87654321 —U106— —U109— —U134— —U121— ACDC_STB 110v0010 11011111 1v10110v 10110000 —U130— MUX_STB 10011101 IC pins: Q8=11, Q7=12, Q6=13, Q5=14, Q4=7, Q3=6, Q2=5, Q1=4...
  • Page 71 2-58 Troubleshooting Test 601.2 — AMP SHUNT Bank AMP/OHM Inputs INPUT HI to AMPS Short Expected Value 0.084 volts Limits 0.02 volts Fault Message AC AMP SHUNT Description The previous test sets up the circuit for this test. There is a routine in soft- ware that generates a waveform for the ACV tests.
  • Page 72 Troubleshooting 2-59 Test 601.3 — AMP SHUNT Bank AMP/OHM Inputs INPUT HI to AMPS Short Expected Value <none specified> Limits <none specified> Fault Message <none> Description This phase resets the circuit to a known state and turns the waveform sig- nal off.

  • Page 73: Disassembly

    Disassembly...

  • Page 74: Introduction

    Disassembly Introduction This section explains how to handle, clean, and disassemble the Model 2000 Multimeter. This section is organized as follows: • Handling and cleaning — Describes how to properly handle, clean, and solder PC boards. • Static sensitive devices — Explains how to handle ICs and CMOS devices.

  • Page 75: Handling And Cleaning

    Disassembly Handling and cleaning To avoid contaminating PC board traces with body oil or other foreign matter, avoid touching the PC board traces while you are repairing the instrument. Motherboard areas covered by the shield have high impedance devices or sensitive circuitry where contamination could cause de- graded performance.

  • Page 76: Static Sensitive Devices

    Use the following assembly drawings to assist you as you disassemble and re-assemble the Model 2000. Also, refer to these drawings for information about the Keithley part numbers of most mechanical parts in the unit. The drawings are located at the end of this section of the man- ual.

  • Page 77: Case Cover Removal

    Disassembly Case cover removal If you need to troubleshoot the instrument or replace a component, you must gain access to the components by removing the case. WARNING Before removing the case cover, disconnect the line cord and any test leads from the instru- ment.

  • Page 78: Changing Trigger Link Lines

    Routine Maintenance Changing trigger link lines The Model 2000 uses two lines of the Trigger Link rear panel connector as External Trigger (EXT TRIG) input and Voltmeter Complete (VMC) output. At the factory, line 1 is configured as VMC and line 2 as EXT TRIG.

  • Page 79: Motherboard Removal

    Disassembly Motherboard removal Perform the following steps to remove the motherboard. This procedure assumes that the case cover is already removed. Remove the IEEE-488 and RS-232 fasteners. The IEEE-488 and the RS-232 connectors each have two nuts that secure the connectors to the rear panel.

  • Page 80: Front Panel Disassembly

    Disassembly Front panel disassembly Use the following procedures to remove the display board and/or the pushbutton switch pad: NOTE You must first remove the case cover, the front/rear input switch, and the front input terminal wires as described in earlier in this section. Unplug the display board ribbon cable from connector J1014.

  • Page 81: Main Cpu Firmware Replacement

    Disassembly Main CPU firmware replacement Changing the firmware may be necessary as upgrades become available. The firmware revi- sion level for the main CPU is displayed during the power-on sequence. The firmware for the main CPU is located in the EPROMs U156 (EVEN) and U157 (ODD), leadless ICs that resides in chip carriers on the PC board.

  • Page 82: Removing Power Components

    Perform the following steps to remove the power transformer: Remove motherboard. Unplug the transformer wires that attach to the power module at the rear panel. During re-assembly, use drawing 2000-050 as a reference and replace the wires as fol- lows: Top wire...

  • Page 83: Power Module

    Perform the following steps to remove the power module: Remove motherboard. Unplug the transformer wires that attach to the power module at the rear panel. During re-assembly, use drawing 2000-050 as a reference and replace the wires as fol- lows: Top wire...

  • Page 84: Instrument Re-Assembly

    3-12 Disassembly Instrument re-assembly Re-assemble the instrument by reversing the previous disassembly procedures. Make sure that all parts are properly seated and secured and that all connections are properly made. To en- sure proper operation, replace and securely fasten the shield. WARNING To ensure continued protection against electrical shock, verify that power line ground (green and yellow wire attached to the power module) and the power transformer ground (black...

  • Page 89: Replaceable Parts

    Replaceable Parts...

  • Page 90: Parts Lists

    Model 2000. Parts list The electrical parts lists for the Model 2000 are shown in Tables 4-1 to 4-3. For part numbers to the various mechanical parts and assemblies, use the Miscellaneous parts list and the assem- bly drawings provided at the end of Section 3.

  • Page 91: Factory Service

    Write ATTENTION REPAIR DEPARTMENT and the RMA number on the shipping la- bel. Components layouts The component layouts are provided in the following pages: Motherboard: 2000-250, pages 1 and 2 Connector board: 2000-250, pages 1 and 2 Display board: 2000-250, pages 3 and 4...
  • Page 92 Replaceable Parts Table 4-1 Model 2000 connector board, parts list Circuit desig. Description Keithley part no. C101 CAP, .1UF, 10%, 25V, CERAMIC (0805) C-495-.1 J1034 CONN, MALE RT ANGLE, 32-PIN CS-456 P1017 CABLE ASSEMBLY CA-123-14A R196 RES, 2.21K, 1%, 100MW, THICK FILM (0805) R-418-2.21K...
  • Page 93 Replaceable Parts Table 4-3 Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. CONTACT, FUSE 2001-314B CRIMP CONTACT ROUND CS-760 HEAT SINK FOR U124 HS-41 SOCKET PLCC-032-T-A FOR U156,157 SO-143-32 SPRING, COMPRESSION SP-5 4-40X5/16 PHILLIPS PAN HD FOR IEEE CS TO BD...
  • Page 94 Replaceable Parts Table 4-3(cont.) Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. C241 CAP, .01UF, 10%, 50V CERAMIC(0805) C-491-.01 C242,243 CAP, .01UF, 10%, 50V CERAMIC(0805) C-491-.01 C244 CAP, 1000pF, 20%, 50V, CERAMIC (1206) C-418-1000P CR102,103 DIODE,BRIDGE,VM18 RF-52...
  • Page 95 Replaceable Parts Table 4-3(cont.) Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. R109 RES, 1K, 1%, 125mW, METAL FILM (1206) R-391-1K R110,133 RES NET, 9K-1K, MICRO DIVIDER TF-246-2 R114 RES, 604, 1%, 100MW THICK FILM(0805) R-418-604 R115 RES, 5K, .1%, WIREWOUND...
  • Page 96 Replaceable Parts Table 4-3(cont.) Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. R220,221,264,212,217 RES, 2.21K, 1%, 100MW, THICK FILM (0805) R-418-2.21K R225 RES, 470,5%, 125MW, METAL FILM(1206) R-375-470 R226,228,235,237,250,252,255 RES, 475, 1%, 100MW, THICK FILM (0805) R-418-475 R234 RES, 5.11K, 1%, 100MW, THICK FILM (0805)
  • Page 97 Replaceable Parts Table 4-3(cont.) Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. U106,109,121,130,134 IC, 8 STAGE SHIFT/STORE,MC14094BD(SOIC) IC-772 U107,108 IC, PHOTO, DARLINGTON TRANS, PS2506L-1 IC-911 U110 IC,TRMS TO DC CONVERTER, 637JR (SOLIC) IC-796 U112 IC, J-FET OP-AMP LF357M(SOIC)
  • Page 98 4-10 Replaceable Parts Table 4-3(cont.) Model 2000 motherboard, parts list Circuit desig. Description Keithley part no. VR101,114 VAR, 576V METAL OXIDE VR-5 VR102 DIODE, ZENER 6.2V, BZX84B6V2 (SOT-23) DZ-87 VR103,104 DIODE, ZENER, 6.8V,MMSZ5235BT1 (SOD-23) DZ-100 VR105,106,115,116 DIODE, ZENER 11V,MMSZ11T1 (SOD-123)
  • Page 99 Replaceable Parts 4-11 Table 4-4(cont.) Model 2000 mechanical, parts list Description Keithley part no. BANANA JACK, PUSH-IN, BLACK BJ-13-0 BANANA JACK, PUSH-IN, RED BJ-13-2 BEZEL, REAR 428-303D BRACKET, REAR PANEL SCANNER COVER PLATE 2001-328C CABLE CLAMP FOR DISPLAY CABLE & TR-299 WIRE CC-37 CABLE CLAMP TIE WRAP, NYLON, 4"...
  • Page 100 4-12 Replaceable Parts Table 4-5 Model 2000 miscellaneous, parts list Description Keithley part no. CALIBRATION MANUAL PACKAGE 2000-905-00 COVER PANEL, SCANNER 2001-372A DISK PROGRAMMING 2000-DSK-81 HANDLE 428-329F LINE CORD CO-7 QUICK REFERENCE GUIDE PACKAGE 2000-903-00 TEST LEADS CA-22 USER'S MANUAL PACKAGE...

  • Page 103: Specifications

    Specifications...
  • Page 104 Speeds include measurement and binary data transfer out the GPIB. ASCII READINGS TO RS-232 (19.2K BAUD): 55/s. Auto zero off. MAX. INTERNAL TRIGGER RATE: 2000/s. Sample count = 1024, auto zero off. MAX. EXTERNAL TRIGGER RATE: 500/s. Auto zero off, NPLC = 0.01.
  • Page 105 2000 6 ⁄ -Digit Multimeter TRUE RMS AC VOLTAGE AND CURRENT CHARACTERISTICS ACCURACY : ±(% of reading + % of range), 23°C ±5 °C VOLTAGE CALIBRATION 3 Hz– 10 Hz– 20 kHz– 50 kHz– 100 kHz– RANGE RESOLUTION CYCLE 10 Hz...

  • Page 106: Frequency And Period Characteristics

    2000 6 ⁄ -Digit Multimeter FREQUENCY AND PERIOD CHARACTERISTICS TRIGGERING AND MEMORY RESOLUTION ACCURACY READING HOLD SENSITIVITY: 0.01%, 0.1%, 1%, or 10% of reading. FREQUENCY PERIOD GATE ±(ppm of 90 DAY/1 YEAR TRIGGER DELAY: 0 to 99 hrs (1ms step size).
  • Page 107 Index AMPS fuse replacement 1-4 Main CPU firmware replacement 3-9 Analog signal switching states 2-13 Motherboard removal 3-7 Assembly drawings 3-4 Ordering information 4-2 Built-in Test documentation 2-22 Built-in Test overview 2-18 Parts list 4-2 Power supply checks 2-11 Case cover removal 3-5 Power-on test 2-3 Changing trigger link lines 3-6 Principles of operation 2-5...
  • Page 108 Service Form Model No. _________________ Serial No. ______________________ Date_________________ Name and Telephone No. ________________________________________________________ Company ______________________________________________________________________ List all control settings, describe problem and check boxes that apply to problem. _________________________ __________________________________________________________________________________________ __________________________________________________________________________________________ Intermittent Analog output follows display Particular range or function bad; specify _______________________________ IEEE failure Obvious problem on power-up...
  • Page 109 Specifications are subject to change without notice. All Keithley trademarks and trade names are the property of Keithley Instruments, Inc. All other trademarks and trade names are the property of their respective companies. Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: 440-248-6168 1-888-KEITHLEY (534-8453) •...

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