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Fluke 87 V/AN Service Manual

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PN 2153596
July 2004
© 2004 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.
Limited permission for the U.S. Government to reproduce Fluke
Item #2153596 is provided pursuant to FAR 52.227.14 Alt. II.
87 V/AN
Digital Multimeter
Service Manual
®

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  Summary of Contents for Fluke 87 V/AN

  • Page 1 Limited permission for the U.S. Government to reproduce Fluke Item #2153596 is provided pursuant to FAR 52.227.14 Alt. II. PN 2153596 July 2004 © 2004 Fluke Corporation, All rights reserved. Printed in USA All product names are trademarks of their respective companies.
  • Page 2 Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the applicable international price.
  • Page 3: Table Of Contents

    Table of Contents Title Page Introduction ....................... 1 Contacting Fluke ....................1 Unpacking the Meter..................2 Inspection...................... 2 Inspection Interval ..................2 Preparations for Use..................2 Precautions and Safety Information ..............2 Electrical Symbols .................... 4 Specifications ....................5 General Specifications .................. 5 Detailed Specifications .................
  • Page 4 87 V/AN Service Manual Backlight....................... 18 Beeper ......................18 Troubleshooting ....................19 Restoration Actions..................19 Basic Maintenance .................... 19 Cleaning the Meter..................19 Opening the Meter Case ................20 Accessing the PCA and Replacing the LCD..........21 Reassembling the Meter Case............... 22 Replacing the Battery..................
  • Page 5 MIN MAX Recording Specifications..............8 Input Path Components ..................11 Overload Protection Components................12 Required Tools and Equipment ................24 Display Features ....................25 Accuracy Tests ...................... 27 Calibration Adjustment Steps................32 87 V/AN Final Assembly ..................33 A1 Main PCA ......................35...
  • Page 6 87 V/AN Service Manual...
  • Page 7 Opening the Meter, Battery and Fuse Replacement ..........20 Removing LCD Mask to Access LCD ..............21 Testing the Current Input Fuses................23 Display Features ....................25 Restoring the Default Password ................30 87 V/AN Final Assembly ..................34 A1 LED PCA......................39...
  • Page 8 87 V/AN Service Manual...
  • Page 9: Introduction

    • Replaceable parts and schematics For complete operating instructions, refer to the 87 V/AN Users Manual. Contacting Fluke To contact Fluke or locate the nearest Service Center, call one of the following telephone numbers: USA: 1-888-44-FLUKE (1-888-443-5853) Canada: 1-800-36-FLUKE (1-800-363-5853)
  • Page 10: Unpacking The Meter

    Open the Multimeter box. Inside you will find the 87 V/AN Digital Multimeter (hereafter referred to as “the Meter”) the test leads, the Product Manuals CD, the printed 87 V/AN User Manual, and the printed 87 V/AN Service Manual (this manual). Remove the Meter from its plastic wrapping.
  • Page 11 Digital Multimeter Precautions and Safety Information • Do not apply more than the rated voltage, as marked on the Meter, between the terminals or between any terminal and earth ground. • Never operate the Meter with the cover removed or the case open.
  • Page 12: Electrical Symbols

    87 V/AN Service Manual Electrical Symbols Electrical symbols used on the Meter and in this manual are explained in Table 1. Table 1. Electrical Symbols AC (Alternating Current) Earth ground DC (Direct Current) Fuse Conforms to European Union Hazardous voltage.
  • Page 13: Specifications

    Digital Multimeter Specifications Specifications General Specifications Maximum Voltage between any Terminal and Earth Ground: 1000 V rms Fuse Protection for mA or µA inputs: 44/100 A, 1000 V FAST Fuse Fuse Protection for A input: 11 A, 1000 V FAST Fuse Display: Digital: 6000 counts updates 4/sec.
  • Page 14 87 V/AN Service Manual Table 2. AC Voltage Function Specifications Function Range Resolution Accuracy 440 Hz - 1 45 - 65 Hz 30 - 200 Hz 200 - 440 Hz 1 - 5 kHz 5 - 20 kHz ± (0.7 % + 4) ±...
  • Page 15 Digital Multimeter Specifications Table 5. Current Function Specifications 1, 2 Function Range Resolution Accuracy Burden Voltage (typical) ± (1.0 % + 2) 60.00 mA 0.01 mA 1.8 mV/mA ± (1.0 % + 2) 400.0 mA 0.1 mA 1.8 mV/mA ± (1.0 % + 2) 6.000 A 0.001 A 0.03 V/A...
  • Page 16 87 V/AN Service Manual Table 8. Frequency Counter Sensitivity and Trigger Levels Minimum Sensitivity (RMS Sine wave) Approximate Trigger Input Range Level 5 Hz - 20 kHz 0.5 Hz - 200 kHz (DC Voltage Function) 600 mV dc 70 mV (to 400 Hz)
  • Page 17: Theory Of Operation

    Theory of Operation Theory of Operation This section provides the theory of operation for the 87 V/AN Digital Multimeter to a depth that is required for troubleshooting to the component level. The functional block diagram provides an overview for the description. The schematic diagrams included in the manual are referred to during the following detailed circuit descriptions.
  • Page 18: Power Supply And Voltage Reference

    Reference Supply ama101f.eps Figure 1. 87 V/AN Block Diagram Power Supply and Voltage Reference A 9-V alkaline battery supplies power to the Meter and is connected via a cable assembly to J3 on the A1 printed circuit assembly (PCA). Diode CR3 protects the Meter from damage due to accidental polarity reversal at J3.
  • Page 19: Function Selection And Overload Protection

    Digital Multimeter Theory of Operation enabled and disabled via control line V5* from microprocessor U2. C15 bypasses the output of U10. When U10 is enabled, 5 V is supplied to the voltage reference U8 input. U8 is a 2.5-V reference with a buffered output and accurately holds the COMMON input 2.5 V above the -2.5 V power supply or at 0 V.
  • Page 20 87 V/AN Service Manual The Meter uses diode clamps, a positive temperature coefficient thermistor, metal oxide varistors (MOVs) and fuses for protection when inadvertent overload conditions are applied across the input terminals. Table 12 shows the components that limit and direct overload currents to prevent damage to the Meter.
  • Page 21: Analog Signal Conditioning

    Digital Multimeter Theory of Operation Internal diodes on each pin of U1 clamp the voltage to a diode drop above or below the power supply levels. Further, U1 power supplies are internally clamped together to prevent overvoltage damage to circuits within U1. U1 pins 1 & 36 have the positive clamp tied to the voltage at CPH (U1 pin 32), which is approximately 5 V above the 2.5-V power supply when the charge pump and current source in U1 are enabled.
  • Page 22: Vdc

    87 V/AN Service Manual within the band pass specification of the Meter. The signal at ACAMP_O is routed to the Low-Pass Filter and/or the RMS Converter using multiplexer U12. The output of Low- Pass Filter or the RMS Converter is routed back into CONV_IN (U1 pin13), filtered, buffered and passed to FE_O (U1 pin 19) ready for measurement.
  • Page 23: Ohms In The 6 Mω & 50 Mω Range And Siemens In The 60 Ns Range

    Digital Multimeter Theory of Operation routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency or duty cycle measurement. Ohms in the 6 MΩ & 50 MΩ Range and Siemens in the 60 nS Range The U1 current source is enabled and routed to ISRC (U1 pin 36) and on to the V/Ohms input jack, which is also connected to DIV_A (U1 pin 3) via the components indicated in Table 11.
  • Page 24: Ma, Μa And Adc

    87 V/AN Service Manual scaled voltage at ACAMP_O is also routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency measurement. mA, µA and ADC The mA/µA input and the A input are connected to R4 (U1 pin 10) as described in Table 11.
  • Page 25: Analog To Digital Converter

    Digital Multimeter Theory of Operation Analog to Digital Converter U3 is a 20-bit Σ∆ analog-to-digital converter (ADC). C21 & C22 are power-supply bypass capacitors. The DC signal at FE_O (U1 pin 19) provides the signal input for U3. The reference for conversion is supplied by U8 as described in 1.3 to the REF and VIN* (compliment of VIN) inputs.
  • Page 26: Microprocessor & Support Circuits

    87 V/AN Service Manual sense lines PB1, PB2 & PB3 with one switch from each strobe group per sense line. U2 pulls each strobe line to -2.5 V in sequence and monitors the sense lines. U2 can determine which switch is closed, debounce and handle multiple switch closures.
  • Page 27: Troubleshooting

    Meter. Periodically wipe the Meter case with Fluke “MeterCleaner” or a damp cloth and mild detergent. Dirt or moisture in the A or mA µA input terminals can affect readings and can falsely activate the Input Alert feature without the test leads being inserted.
  • Page 28: Opening The Meter Case

    87 V/AN Service Manual Opening the Meter Case WCaution To avoid unintended circuit shorting, always place the uncovered Meter assembly on a protective surface. When the case of the Meter is open, circuit connections are exposed. To open the Meter case, refer to Figure 2 and do the following: 1.
  • Page 29: Accessing The Pca And Replacing The Lcd

    Digital Multimeter Basic Maintenance Accessing the PCA and Replacing the LCD Once the case has been opened, the A1 Main PCA can easily be removed. The shields disconnect from the PCA as follows: 1. Remove the five Phillips-head screw securing the top and bottom shields to the PCA. 2.
  • Page 30: Reassembling The Meter Case

    87 V/AN Service Manual Reassembling the Meter Case To reassemble the Meter case: 1. Verify that the rotary knob and circuit board switch are in the position, and that the gasket remains secured to the bottom case. 2. Place the PCA into the bottom case.
  • Page 31: Replacing The Fuses

    Digital Multimeter Basic Maintenance 3. The display should indicate between 00.0 Ω and 00.5 Ω. If the display reads OL, replace the fuse and test again. If the display reads another value, further servicing is required. 4. To test F1, move the probe from the A input terminal to the mA/UA input terminal. 5.
  • Page 32: Required Equipment

    87 V/AN Service Manual Required Equipment Required equipment for the performance tests is listed in Table 13. If the recommended models are not available, equipment with equivalent specifications may be used. XW Warning • To avoid shock or injury, do not perform the verification tests or calibration adjustment procedures described in this manual unless you are qualified to do so.
  • Page 33: Basic Operability Tests

    Digital Multimeter Performance Tests Basic Operability Tests Refer to the following sections to test the basic operability of the Meter. Testing the Fuses Refer to “Testing Fuses (F1 and F2)”. Testing the Display Turn the Meter on while holding down D to view all segments of the display. Compare the display with the appropriate examples in Figure 5 and Table 14.
  • Page 34 87 V/AN Service Manual Table 14. Display Features (cont.) Number Feature Indication The battery is low. XWWarning: To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator appears.
  • Page 35: Testing The Pushbuttons

    Digital Multimeter Performance Tests Testing the Pushbuttons To test the pushbuttons 1. Turn the Meter rotary knob to J. 2. Press each button and note that the meter responds with a beep for each button press. 3. Press and hold B a second time to exit MIN MAX mode. Testing Meter Accuracy Perform the accuracy test steps in Table 15.
  • Page 36 87 V/AN Service Manual Table 15. Accuracy Tests (cont.) Step Test Function Range 5500A Output Display Reading 60 nS Open input -0.10 to 0.10 Conductance 60 nS 100 MΩ 9.80 to 10.20 3.0 V dc 2.939 to 3.061 Diode 3.0 A, 60 Hz 2.968 to 3.032...
  • Page 37: Calibration Adjustment

    Digital Multimeter Calibration Adjustment Calibration Adjustment The Meter features closed-case calibration adjustment using known reference sources. The Meter measures the applied reference source, calculates correction factors and stores the correction factors in nonvolatile memory. The following sections present the features and Meter pushbutton functions that can be used during the Calibration Adjustment Procedure.
  • Page 38: Restoring The Default Password

    87 V/AN Service Manual Restoring the Default Password If the calibration password is forgotten, the default password (1234) can be restored using the following steps. 1. While holding down B, turn the rotary knob from OFF to VAC. The Meter displays “Z CAL”.
  • Page 39: Meter Buttons Used In The Calibration Steps

    Digital Multimeter Calibration Adjustment Meter Buttons Used in the Calibration Steps The Meter buttons behave as follows when performing the Calibration Adjustment Procedure. This may be of help determining why a calibration step is not accepted and for determining the input value without referring to Table 16. Press and hold to show the measured value.
  • Page 40 87 V/AN Service Manual Notes Set the calibrator to Standby prior to changing the function switch position and or after completing adjustment of each function. If the calibration adjustment procedure is not completed correctly, the Meter will not operate correctly.
  • Page 41: Service And Parts

    Digital Multimeter Service and Parts Service and Parts Replacement parts are shown in Table 17, Table 18, and Figures 7 and 8. To order parts and accessories, refer to “Contacting Fluke”. Table 17. 87 V/AN Final Assembly Reference Part Manufacturer’s Description...
  • Page 42 87 V/AN Service Manual TL75 Test Lead Set MP31 AC72 (Option) Holster Alligator Clips MP15 Tilt Stand H1 (4) MP22 H5, 6 axp015.eps Figure 7. 87 V/AN Final Assembly...
  • Page 43 Digital Multimeter Service and Parts Table 18. A1 Main PCA Reference Part Manufacturer’s Description Cage Designator Number Part Number CAPACITOR,FILM,POLYESTER,0.022UF, 2117948 65964 MMK10223K1000A04L4 1 +-10%,1000V,10MM LS RADIAL,BULK CAPACITOR, SMR,CAP,CER,0.01UF, C2 C39 C57 644838 04222 06035C103KAT2A +-10%,50V,X7R,0603 CAPACITOR, SMR,CAP,CER,180PF, 689588 04222 08051A181JAT1A +-5%,100V,C0G,0805 C4-5 C8 C12...
  • Page 44 87 V/AN Service Manual Table 18. A1 Main PCA (cont.) Reference Part Manufacturer’s Description Cage Designator Number Part Number NPN,MMBT3904 Q3 Q6 Q14 SMR,TRANSISTOR,SI,NPN,60V,350MW,SO 742676 89536 742676 T-23 TRANSISTOR,SI,NPN,MMBT5089,30V,50M Q4-5 Q8 Q17 820902 65940 SST5089 A,50MHZ,200MW,SOT-23,TAPE TRANSISTOR,SI,PNP,MMBT3906,40V,200 742684 89536 742684...
  • Page 45 Digital Multimeter Service and Parts Table 18. A1 Main PCA (cont.) Reference Part Manufacturer’s Description Cage Designator Number Part Number RESISTOR, SMR,RES,CERM,475K, R44 R47 943530 18612 CRCW-1206-4753F-RT2 2 +-1%,.125W,100PPM,1206 RESISTOR, SMR,RES,CERM,1K, 649720 18612 CRCW-0603-1001FRT1 +-1%,.063W,100PPM,0603 RESISTOR, SMR,RES,CERM,12.1,+- 930081 18612 CRCW-0805-12R1F-RT1 1 1%,0.1W,100PPM,0805 RESISTOR,METAL FILM,24.9K,+- 2094011...
  • Page 46: Schematic Diagrams

    87 V/AN Service Manual Table 18. A1 Main PCA (cont.) Reference Part Manufacturer’s Description Cage Designator Number Part Number IC,RMS CONVERTER,AD737J-5,+-2.5V,LOW 2089072 24355 AD737JR-5 POWER,LOW SUPPLY VOLTAGE,SO8,TAPE IC,VOLTAGE REFERENCE,LT1790,2.5V,0.1%,25PPM/C,60 1622188 64155 LT1790ACS6-2.5 UA,SOT-23-6,TAPE IC,VOLTAGE REGULATOR, LINEAR, TPS77050,5V,50MA,LDO,LOW POWER,SOT- 1642135 01295...
  • Page 47 Digital Multimeter Schematic Diagrams 8X-5-4001 Figure 8. A1 LED PCA...
  • Page 48 87V/AN Service Manual TEST POINTS 800 HZ FILTER (MODEL 87 ONLY) (MODEL 83 ONLY) REF DES NAME REF DES NAME S1-9 R112 RMS/AVG CONVERTER 0.0068U +2.5 S1-14 SERIAL COMM S1-10 TP23 R113 S1-3 TP24 +2.5 S1-1 AD737J-2.5 S1-2 JTAG MMBT3906 102K 107K 97.6K...
  • Page 49 Digital Multimeter Schematic Diagrams POWER SUPPLY TEST POINTS TP17 TP16 TP15 IRLML6302 +2.5 REF DES NAME REF DES NAME TPS77050 5.0V S1-9 845K S1-14 SERIAL COMM 1.00M S1-10 TP23 0.1U 1.00M 1.00M S1-3 TP24 +0.8 S1-1 GF1B S1-6 JTAG TPS71533 LCD COMPENSATION S1-7 TP25...
  • Page 50 87V/AN Service Manual...