Fluke 87 V-an User Manual

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Limited permission for the U.S. Government to reproduce Fluke

87 V/AN

Digital Multimeter

Service Manual

Item #2153596 is provided pursuant to FAR 52.227.14 Alt. II.

PN 2153596 July 2004

LIMITED WARRANTY AND LIMITATION OF LIABILITY

Each Fluke product is warranted to be free from defects in material and workmanship under normal use and service. The warranty period is one year and begins on the date of shipment. Parts, product repairs, and services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal conditions of operation or handling. Fluke warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non-defective media. Fluke does not warrant that software will be error free or operate without interruption.

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. Fluke reserves the right to invoice Buyer for importation costs of repair/replacement parts when product purchased in one country is submitted for repair in another country.

Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair, or replacement of a defective product which is returned to a Fluke authorized service center within the warranty period.

To obtain warranty service, contact your nearest Fluke authorized service center to obtain return authorization information, then send the product to that service center, with a description of the difficulty, postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal condition of operation or handling, including overvoltage failures caused by use outside the product’s specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of repair costs and obtain authorization before commencing the work. Following repair, the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges (FOB Shipping Point).

THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR THEORY.

Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court or other decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any other provision.

Fluke Corporation P.O. Box 9090 Everett, WA 98206-9090 U.S.A.

Fluke Europe B.V. P.O. Box 1186 5602 BD Eindhoven The Netherlands

11/99

To register your product online, visit register.fluke.com

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................................................................................. 5

Theory of Operation.......................................................................................... 9

Functional Block Diagram............................................................................ 9

Power Supply and Voltage Reference .......................................................... 10

Function Selection and Overload Protection ................................................ 11

Analog Signal Conditioning......................................................................... 13

VAC.......................................................................................................... 13

VDC.......................................................................................................... 14

mVDC ...................................................................................................... 14

Temperature.............................................................................................. 14

Ohms Below the 6 MΩ Range.................................................................. 14

Ohms in the 6 MΩ & 50 MΩ Range and Siemens in the 60 nS Range.... 15

Continuity in all Ohms and the Siemens Ranges...................................... 15

Capacitance............................................................................................... 15

Diode Test ................................................................................................ 15

mA, µA and AAC..................................................................................... 15

mA, µA and ADC..................................................................................... 16

Active Filter.................................................................................................. 16

800 Hz Low Pass Filter................................................................................. 16

RMS to DC Converter.................................................................................. 16

Analog to Digital Converter ......................................................................... 17

Secondary Analog Circuits........................................................................... 17

Keypad.......................................................................................................... 17

Microprocessor & Support Circuits.............................................................. 18

LCD .............................................................................................................. 18

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.................................................................................... 22

Testing Fuses and Current Circuitry............................................................. 22

Replacing the Fuses...................................................................................... 23

Required Equipment.......................................................................................... 24

Performance Tests............................................................................................. 24

Basic Operability Tests................................................................................. 25

Testing the Fuses .......................................................................................... 25

Testing the Display....................................................................................... 25

Testing the Pushbuttons................................................................................ 27

Testing Meter Accuracy................................................................................ 27

Calibration Adjustment..................................................................................... 29

Calibration Adjustment Counter................................................................... 29

Calibration Adjustment Password................................................................. 29

Changing the Password............................................................................ 29

Restoring the Default Password ............................................................... 30

Meter Buttons Used in the Calibration Steps................................................ 31

Calibration Adjustment Procedure................................................................ 31

Service and Parts............................................................................................... 33

Schematic Diagrams.......................................................................................... 38

List of Tables

Table Title Page

1. Electrical Symbols................................................................................................. 4

2. AC Voltage Function Specifications..................................................................... 6

3. DC Voltage, Resistance, and Conductance Function Specifications..................... 6

4. Temperature Specifications................................................................................... 6

5. Current Function Specifications............................................................................ 7

6. Capacitance and Diode Function Specifications................................................... 7

7. Frequency Counter Specifications......................................................................... 7

8. Frequency Counter Sensitivity and Trigger Levels............................................... 8

9. Electrical Characteristics of the Terminals............................................................ 8

10. MIN MAX Recording Specifications.................................................................... 8

11. Input Path Components......................................................................................... 11

12. Overload Protection Components.......................................................................... 12

13. Required Tools and Equipment............................................................................. 24

14. Display Features.................................................................................................... 25

15. Accuracy Tests ...................................................................................................... 27

16. Calibration Adjustment Steps................................................................................ 32

17. 87 V/AN Final Assembly...................................................................................... 33

18. A1 Main PCA........................................................................................................ 35

iii

87 V/AN

Service Manual

List of Figures

Figure Title Page

1. 87 V/AN Block Diagram....................................................................................... 10

2. Opening the Meter, Battery and Fuse Replacement.............................................. 20

3. Removing LCD Mask to Access LCD.................................................................. 21

4. Testing the Current Input Fuses............................................................................. 23

5. Display Features.................................................................................................... 25

6. Restoring the Default Password ........................................................................... 30

7. 87 V/AN Final Assembly...................................................................................... 34

8. A1 LED PCA......................................................................................................... 39

87 V/AN

Service Manual

Introduction

To avoid shock or injury:

• Read “Precautions and Safety Information” before

performing the verification tests or calibration adjustment procedures documented in this manual.

• Do not perform the verification tests or calibration

adjustment procedures described in this manual unless you are qualified to do so.

• The information provided in this manual is for the use of

qualified personnel only.

• The 87 V/AN Digital Multimeter contains parts that can be

damaged by static discharge.

• Follow the standard practices for handling static sensitive

devices.

The 87 V/AN Service Manual provides the following information:

XW Warning

WCaution

• Safety information

• Specifications

• Theory of operation

• Basic maintenance (cleaning, replacing the battery and fuses)

• Performance test procedures

• Calibration adjustment procedures

• 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) Europe: +31 402-675-200 Japan: +81-3-3434-0181 Singapore: +65-738-5655 Anywhere in the world: +1-425-446-5500

Or, visit Fluke's Web site at www.fluke.com

To register your product, visit register.fluke.com

87 V/AN

Service Manual

Unpacking the Meter

Inspection

Inspection Interval

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.

Inspect all contents for any visible shipping damage. Look for scratches or any other damage. If the unit is damaged, contact Fluke immediately using the contact information stated previously.

Inspect the Meter and test leads before each use.

XWWarning

To avoid possible electric shock or personal injury, inspect the test leads for damaged insulation or exposed metal. Check the test leads for continuity. Replace damaged test leads before using the Meter.

Preparations for Use

Before using or servicing the Meter, read all associated safety information. Make sure you have complete understanding of all safety issues.

Precautions and Safety Information

In this manual, a Warning identifies conditions and actions that pose hazard(s) to the user; a Caution identifies conditions and actions that may damage the Meter or the test instruments.

XWWarning

To avoid possible electric shock or personal injury, follow these guidelines:

• Use this Meter only as specified in this manual or the

protection provided by the Meter might be impaired.

• Do not use the Meter if it is damaged. Before using the

Meter, inspect the case. Look for cracks or missing plastic. Pay particular attention to the insulation surrounding the connectors.

• Make sure the battery door is closed and latched before

operating the Meter.

• Replace the battery as soon as the battery indicator (M)

appears.

• Remove test leads from the Meter before opening the

battery door.

• Inspect the test leads for damaged insulation or exposed

metal. Check the test leads for continuity. Replace damaged test leads before using the Meter.

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.

• Use caution when working with voltages above 30 V ac rms,

42 V ac peak, or 60 V dc. These voltages pose a shock hazard.

• Use only the replacement fuses specified in this manual.

• Use the proper terminals, function, and range for

measurements.

• Avoid working alone.

• When measuring current, turn off circuit power before

connecting the Meter in the circuit. Remember to place the Meter in series with the circuit.

• When making electrical connections, connect the common

test lead before connecting the live test lead; when disconnecting, disconnect the live test lead before disconnecting the common test lead.

• Do not use the Meter if it operates abnormally. Protection

may be impaired. When in doubt, have the Meter serviced.

• Do not operate the Meter around explosive gas, vapor, or

dust.

• Use only a single 9 V battery, properly installed in the Meter

case, to power the Meter.

• When servicing the Meter, use only specified replacement

parts.

• When using probes, keep fingers behind the finger guards

on the probes.

• Do not use the Low Pass Filter option to verify the presence

of hazardous voltages. Voltages greater than what is indicated may be present. Make a voltage measurement without the filter to detect the possible presence of hazardous voltage, then select the filter function.

XCaution

To avoid possible damage to the Meter or to the equipment under test, follow these guidelines:

• Disconnect circuit power and discharge all high-voltage

capacitors before testing resistance, continuity, diodes, or capacitance.

• Before measuring current, check the Meter's fuses.

See " Testing Fuses (F1 and F2) ”.

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

B F

CAT III

AC (Alternating Current)

DC (Direct Current)

Hazardous voltage.

Risk of Danger. Important information. See Manual.

Battery

Continuity test or continuity beeper tone.

Underwriters Laboratories

IEC overvoltage category III

CAT III equipment is designed to protect against transients in equipment in fixedequipment installations, such as distribution panels, feeders and short branch circuits, and lighting systems in large buildings.

Inspected and licensed by TÜV Product Services.

CAT IV

Earth ground

Fuse

Conforms to European Union directives

Conforms to relevant Canadian Standards Association directives

Double insulated

Capacitance

Diode IEC overvoltage category IV

CAT IV equipment is designed to protect against transients from the primary supply level, such as an electricity meter or an overhead or underground utility service.

Digital Multimeter

Specifications

General Specifications

Maximum Voltage between any Terminal and Earth Ground: 1000 V rms

W Fuse Protection for mA or µA inputs: 44/100 A, 1000 V FAST Fuse W Fuse Protection for A input: 11 A, 1000 V FAST Fuse

Display: Digital: 6000 counts updates 4/sec. The Meter also has 19,999 counts in high-resolution mode. Analog Bargraph: 33 segments, updates 40/sec. Frequency: 19,999 counts, updates 3/sec at > 10 Hz.

Temperature: Operating: -20 °C to +55 °C; Storage: -40 °C to +60 °C Altitude: Operating: 2000 m; Storage: 10,000 m Temperature Coefficient: 0.05 x (specified accuracy)/ °C (< 18 °C or > 28 °C) Electromagnetic Compatibility: All ranges unless otherwise noted: In an RF field of 3 V/m total

accuracy = specified accuracy + 20 counts Except: Temperature not specified.

Relative Humidity: 0 % to 90 % (0 °C to 35 °C); 0 % to 70% (35 °C to 55 °C) Battery Type: 9 V zinc, NEDA 1604 or 6F22 or 006P Battery Life: 400 hrs typical with alkaline (with backlight off) Vibration: Per MIL-PRF-28800 for a Class 2 instrument Shock: 1 Meter drop per IEC 61010-1:2001 Size (HxWxL): 1.25 in x 3.41 in x 7.35 in (3.1 cm x 8.6 cm x 18.6 cm) Size with Holster and Flex-Stand: 2.06 in x 3.86 in x 7.93 in (5.2 cm x 9.8 cm x 20.1 cm) Weight: 12.5 oz (355 g) Weight with Holster and Flex-Stand: 22.0 oz (624 g) Safety: Complies with ANSI/ISA S82.01-2004, CSA 22.2 No. 1010.1:2004 to 1000 V Overvoltage

Category III, IEC 664 to 600 V Overvoltage Category IV. UL listed to UL61010-1. Licensed by TÜV to EN61010-1.

Detailed Specifications

For all detailed specifications: Accuracy is given as ±([% of reading] + [number of least significant digits]) at 18 °C to

28 °C, with relative humidity up to 90 %, for a period of one year after calibration adjustment. In the 4 ½-digit mode, multiply the number of least significant digits (counts) by 10. AC conversions are ac-coupled and valid from 3 % to 100 % of range. The Meter is true rms responding. AC crest factor can be up to 3 at full scale, 6 at half scale. For non-sinusoidal wave forms add -(2 % Rdg + 2 % full scale) typical, for a crest factor up to 3.

Tables 2 through 10 list the Meter’s detailed specifications.

87 V/AN

is a true rms responding meter. When the input leads are shorted together in the ac functions, the Meter

Service Manual

Table 2. AC Voltage Function Specifications

Function Range Resolution

600.0 mV

2,4

6.000 V

60.00 V

600.0 V

1000 V 1 V Low pass filter ± (0.7 % + 2)

1. Below 10 % of range, add 12 counts.

2. The Meter may display a residual reading between 1 and 30 counts. A 30 count residual reading will cause only a 2-digit change for readings over 3 % of range. Using REL to offset this reading may produce a much larger constant error in later measurements.

3. Frequency range: 1 kHz to 2.5 kHz.

4. A residual reading of up to 13 digits with leads shorted, will not affect stated accuracy above 3 % of range.

5. Specification increases from -1% at 200 Hz to -6% at 440 Hz when filter is in use.

0.1 mV

0.001 V

0.01 V

0.1 V

45 - 65 Hz 30 - 200 Hz

± (0.7 % + 4)

± (0.7 % + 2)

± (1.0 % + 4)

200 - 440 Hz

± (1.0 % + 4)

+1 % + 4

-6 % - 45

Accuracy

440 Hz - 1

kHz

unspecified

1 - 5 kHz 5 - 20 kHz

± (2.0 % + 4)

unspecified unspecified unspecified unspecified

± (2.0 % + 20)

unspecified

Table 3. DC Voltage, Resistance, and Conductance Function Specifications

Function Range Resolution Accuracy

6.000 V

1. When using the REL ∆ function to compensate for offsets.

2. Add 0.5 % of reading when measuring above 30 MΩ in the 50 MΩ range.

60.00 V

600.0 V 1000 V

600.0 mV 0.1 mV ± (0.1 % + 1)

600.0 Ω

6.000 kΩ

60.00 kΩ

600.0 kΩ

6.000 MΩ

50.00 MΩ

60.00 nS

0.001 V

0.01 V

0.1 V 1 V

0.1 Ω

0.001 kΩ

0.01 kΩ

0.1 kΩ

0.001 MΩ

0.01 MΩ

0.01 nS

± (0.05 % + 1) ± (0.05 % + 1) ± (0.05 % + 1) ± (0.05 % + 1)

± (0.2 % + 2)1 ± (0.2 % + 1) ± (0.2 % + 1) ± (0.6 % + 1) ± (0.6 % + 1) ± (1.0 % + 3) ± (1.0 % + 10)

Table 4. Temperature Specifications

Temperature Resolution Accuracy

-200 °C to +1090 °C

-328 °F to +1994 °F

1. Does not include error of the thermocouple probe.

2. Accuracy specification assumes ambient temperature stable to rated accuracy applies after 1 hour.

0.1 °C

0.1 °F

± 1 °C. For ambient temperature changes of ± 5 °C,

1 % + 10 1 % + 18

1,2

Digital Multimeter

Table 5. Current Function Specifications

Function Range Resolution Accuracy

(45 Hz to 2 kHz)

mA [

µA B

(45 Hz to 2 kHz)

µAF

1. AC conversions are ac coupled, true rms responding, and valid from 3 % to 100 % of range, except 400 mA range (5 % to 100 % of range) and 10 A range (15 % to 100 % or range).

2. The Meter is a true rms responding meter. When the input leads are shorted together in the ac functions, the Meter may display a residual reading between 1 and 30 counts. A 30 count residual reading will cause only a 2 digit change for readings over 3 % of range. Using REL to offset this reading may produce a much larger constant error in later measurements

3. W 10 A continuous up to 35 °C; < 20 minutes on, 5 minutes off at 35 °C to 55 °C. 20 A for 30 seconds maximum; > 10 A unspecified.

4. 400 mA continuous; 600 mA for 18 hrs maximum.

60.00 mA

400.0 mA

6.000 A

10.00 A

60.00 mA

400.0 mA

6.000 A

10.00 A

600.0 µA 6000 µA

0.01 mA

0.1 mA

0.001 A

0.01 A

0.01 mA

0.1 mA

0.001 A

0.01 A

0.1 µA 1 µA

± (1.0 % + 2) ± (1.0 % + 2) ± (1.0 % + 2) ± (1.0 % + 2)

± (0.2 % + 4) ± (0.2 % + 2) ± (0.2 % + 4) ± (0.2 % + 2)

± (1.0 % + 2) ± (1.0 % + 2)

± (0.2 % + 4) ± (0.2 % + 2)

1, 2

Burden Voltage (typical)

1.8 mV/mA

0.03 V/A

1.8 mV/mA

0.03 V/A

0.03 V/A 100 µV/µA

100 µV/µA

100 µV/µA 100 µV/µA

Specifications

Table 6. Capacitance and Diode Function Specifications

Function Range Resolution Accuracy

E 10.00 nF

100.0 nF

1.000 µF

10.00 µF

100.0 µF 9999 µF

0.01 nF

0. 1 nF

0.001 µF

0.01 µF

0.1 µF 1 µF

± (1 % + 2)1 ± (1 % + 2) ± (1 % + 2) ± (1 % + 2) ± (1 % + 2) ± (1 % + 2)

G 3.000 V 0.001 V ± (2 % + 1)

1. With a film capacitor or better, using Relative mode to zero residual.

Table 7. Frequency Counter Specifications

Function Range Resolution Accuracy

Frequency (0.5 Hz to 200 kHz, pulse width > 2 µs)

199.99

1999.9

19.999 kHz

199.99 kHz > 200 kHz

0.01 Hz

0.1 Hz

0.001 kHz

0.01 kHz

0.1 kHz

± (0.005 % + 1) ± (0.005 % + 1) ± (0.005 % + 1) ± (0.005 % + 1)

unspecified

87 V/AN

Service Manual

Table 8. Frequency Counter Sensitivity and Trigger Levels

Minimum Sensitivity (RMS Sine wave)

Input Range1

5 Hz - 20 kHz 0.5 Hz - 200 kHz

600 mV dc 600 mV ac 6 V 60 V 600 V 1000 V

Duty Cycle Range Accuracy

0.0 to 99.9 % Within ± (0.2% per kHz + 0.1 %) for rise times < 1 µs.

1. Maximum input for specified accuracy = 10X Range or 1000 V.

70 mV (to 400 Hz) 150 mV

0.3 V 3 V 30 V 100 V

70 mV (to 400 Hz) 150 mV

0.7 V 7 V (≤ 140 kHz) 70 V (≤ 14.0 kHz) 200 V (≤ 1.4 kHz)

Table 9. Electrical Characteristics of the Terminals

Common Mode Rejection Ratio

(1 kΩ unbalance)

Function

Overload

Protection

Input Impedance

(nominal)

L 1000 V rms 10 MΩ < 100 pF > 120 dB at dc,

50 Hz or 60 Hz

1000 V rms 10 MΩ < 100 pF > 120 dB at dc,

50 Hz or 60 Hz

Approximate Trigger

Level

(DC Voltage Function)

40 mV 

1.7 V 4 V 40 V 100 V

Normal Mode Rejection

> 60 dB at 50 Hz or 60 Hz

K 1000 V rms 10 MΩ < 100 pF (ac-

coupled)

> 60 dB, dc to 60 Hz

Full Scale Voltage Typical Short Circuit Current

Open Circuit Test Voltage

To 6.0 MΩ

e 1000 V rms < 7.5 V dc < 4.1

V dc

50 MΩ or

60 nS

< 4.5

V dc

600 Ω

1 mA 100 µA 10 µA 1µA 1 µA 0.5 µA

6 k 60 k 600 k 6 M 50 M

G 1000 V rms < 3.9 V dc 3.000 V dc 0.6 mA typical

1. 10

1. For repetitive peaks: 1 ms for single events.

V Hz max

Table 10. MIN MAX Recording Specifications

Nominal Response Accuracy

100 ms to 80 % (dc functions)

120 ms to 80 % (ac functions)

250 µs (peak)

Specified accuracy ± 12 counts for changes > 200 ms in duration

Specified accuracy ± 40 counts for changes > 350 ms and inputs > 25 % of range Specified accuracy ± 100 counts for changes > 250 µs in duration

(add ± 100 counts for readings over 6000 counts) (add ± 100 counts for readings in Low Pass mode)

Digital Multimeter

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.

Functional Block Diagram

Figure 1 shows the top-level function block diagram for the Meter. Each of the blocks in this diagram is discussed in detail in the following paragraphs.

The parameter to be measured is connected with test leads to the appropriate two input terminals shown at the left of the block diagram. After the Meter is set to the desired function, the signal is routed to the signal conditioning circuit. Either automatically or manually, a range is selected that puts the signal to be measured within the dynamic range of the analog-to-digital converter (ADC) or other signal conditioning circuits like the RMS-to-DC converter discussed in “RMS to DC Converter”. A scaled AC signal voltage is routed directly, or via an 800-Hz low-pass filter, to the RMS-to-DC converter circuit. A DC input signal or DC output of the RMS-to-DC converter (for AC functions) is routed to a low-pass, 6-Hz, 2-pole active filter to prepare it for ADC measurement. The conditioned analog input signal voltage is converted to a digital value by the ADC and sent to the microprocessor. The microprocessor converts this digital value for display on the LCD based on the function, range and keypad entered options. The output of the signal-conditioning block is also routed to the secondary analog circuits block to be further conditioned for input to the fast ADC contained within the microprocessor block. Other analog circuits that control the behavior of the Meter are located in the secondary analog circuits block and are discussed later.

87 V/AN

Service Manual

V/Ohms

mA/µA

AMPS

Common

Low Pass Filter

Power

Supply

Function

Selection

Overload

Protection

Active

Filter

Analog

Signal

Conditioning

Reference

RMS

Converter

Analog

Digital

Converter

Secondary

Analog Circuits

Microprocessor

Support

Circuits

Back-

light

LCD

Keypad

Beeper

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.

Q13 is used as a remote power switch that connects the battery to the power supply regulators when the Meter is turned on. When S1 is in the OFF position, Q14 is off to allow the battery voltage to turn off Q13 via R73. When the Meter is turned on, S1 makes a momentary contact to the battery voltage via R80, turning on Q14, which turns on Q13, which connects the battery voltage to R74, which holds Q14 until S1 is returned to the OFF position.

When Q13 is on, battery voltage is applied to regulators U6 and U10, bypass capacitors C12 and C14 and the low battery detect divider resistors R15 & R16. Note that since the power supply levels are referenced to the COMMON input terminal of the Meter, the negative end of the battery is the -2.5 V power supply.

U6 is a 3.3-V regulator that generates the +0.8-V (-2.5 V + 3.3 V) power supply. U10 is a 5.0-V regulator that generates the +2.5-V (-2.5 V + 5.0 V) power supply. U10 is

ama101f.eps

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. The triangular ground symbol represents this reference level throughout the Meter schematic. C16, C57, C50 and R109 bypass the output of U8 keeping the voltage between COMMON and the -2.5 V power supply noise free and stable. C50 and R109 form a low Q bypass that is directed at electromagnetic interference (EMI).

Function Selection and Overload Protection

Sections of rotary switch S1 connect the V/Ohms and mA/µA input jacks to the signal conditioning circuit as required for the respective Meter functions. The Meter schematic symbols for each of the sections of S1 have the functions that correspond to the closed positions listed next to them. Table 11 indicates the components that complete normal operation signal path/paths from input jacks to the required signal conditioning circuit/circuits for each Meter function.

Table 11. Input Path Components

Function Components

VAC

VDC

mV dc

L -

mV dc – HiZ

Temperature

Ohms (Below 6 MΩ)

Ohms (6 MΩ, 50 MΩ, nS)

Continuity (below 6 MΩ)

Continuity (6 MΩ, 50 MΩ)

HiZ

RT1, R1, R2, C1, Z1(9.997 M), C43, R94

RT1, R1, S1(1,3), Z1(9.997 M)

RT1, R1, S1(1,3), Z1(9.997 M), S1(29,5), R85

RT1, R1, S1(29,5), R85

RT1, R1, S1(1,2), R3, S1(29,5), R85, S1(1,3) Z1(9.997M)

RT1, R1, S1(1,2), R3, Z2, S1(4,5), R85

RT1, R1, S1(1,2), R3, S1(1,3), Z1(9.99 7M)

RT1, R1, S1(1,2), R3, Z2, S1(4,5) R85

RT1, R1, S1(1,2), R3, S1(1,3), Z1(9.997 M)

Capacitance

Diode Test

RT1, R1, S1(1,2), R3, Z2, S1(4,5) R85

RT1, R1, S1(1,2), R3, Z2, S1(4,5), R85

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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.

Table 12. Overload Protection Components

Function Components Protected Protection Components

U1 pin 3 Z1(9.997 M), U1-3 clamps K

VAC

VDC

S1(1,2)(1,3)(29,5)(4,5), Z1(9.997 M) RT1, R1, RV1, RV2, Z2, RV3 U1 pin 3 Z1(9.997 M), U1-3 clamps V

S1(1,2)(29,5)(4,5), Z1(9.997 M) RT1, R1, RV1, RV2, Z2, RV3

L, d

mV dc, Temperature

T, E,X

Ohms, Capacitance, Continuity

Diode Test

U1 pin 36 RT1, R1, CR10, VR1, CR8, CR9, R3, U1-36

clamps

U1 pin 3 RT1, R1, CR10, VR1, CR8, CR9, Z1(9.997 M),

U1-3 clamps

U1 pin 1 RT1, R1, CR10, VR1, CR8, CR9, R85, U1-1

clamps

S1(4,5) Z2, RV3, RV2, RT1, R1, CR10, VR1, CR8,

CR9

U1 pin 36 RT1, R1, CR10, VR1, CR8, CR9, R3, U1-36

clamps

U1 pin 3 RT1, R1, CR10, VR1, CR8, CR9, Z1(9.997 M),

U1-3 clamps

U1 pin 1 Z2, R85, U1-1 clamps

S1(29,5) RT1, R1, CR10, VR1, CR8, CR9

U1 pin 36 RT1, R1, CR10, VR1, CR8, CR9, R3, U1-36

clamps

U1 pin 3 RT1, R1, CR10, VR1, CR8, CR9, R2, C1,

Z1(9.997 M), U1-3 clamps

U1 pin 1 Z2, R85, U1-1 clamps

S1(1,3)(29,5) RT1, R1, CR10, VR1, CR8, CR9

S1(7,8)(7,6) F1, CR1, CR2 Voltage applied to

mA/µA input jack in any of the above functions or OFF

input jack in any function including OFF

U2 pin 3 after F1 opens R7, CR5

R5 F1, CR1, CR2, R6 mA/A

U2 pin 3 after F1 opens R7, CR5

R4 F1, CR1, CR2 µA

U2 pin 3 after F1 opens R7, CR5

R6 F2 (assuming enough current is available) Voltage applied to A

U2 pin 2 after F2 opens R10, CR6

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. When an overload voltage is present on the V/Ohms input jack with respect to the COMMON input jack, clamp diodes in U1 conduct enough to drop the offending voltage on resistors that handle the resulting overload current. Additional clamps, CR8, CR9, CR10 and VR1, are used to keep currents from large overload voltages out of U1 pin 36 by safely clamping the voltage at TP6 to approximately +8.9 V and -2.1 V with respect to COMMON. Positive temperature coefficient thermistor, RT1, will aid the safe handling of the overload by increasing in resistance and thereby reducing the overload current being handled by these additional clamps. R1 is a high voltage resistor that drops the overload voltage until RT1 can catch up.

During voltage overload conditions exceeding approximately ±2 kV at the V/Ohms input jack, the open contacts of S1 need to have the voltage across them kept below the arcover level. RV1, RV2 & RV3 MOVs will conduct and limit the voltage at TP5 and TP11 to a magnitude of less than 2 kV unless TP5 is connected to TP6 by S1(1,2). The voltage at TP6 will be held by clamps CR8, CR9, CR10 and VR1 as described above with RT1 and the high voltage resistor R1 safely dropping the overload voltage.

During voltage or current overload conditions at the mA/µA input jack with the mA/A or µA Meter function selected, current shunts R4, R5 & R6 and the closed contacts of S1 are protected by F1 opening. CR1 & CR2 limit the voltage at the mA/µA input to approximately ±2.1 V regardless of the Meter function selected, thereby protecting the open or closed contacts of S1 (and the current shunts, if connected) while allowing time for F1 to open.

During voltage or current overload conditions at the A input jack current shunt R6 is protected by F2 opening.

C43 and R94, which are in parallel with Z1 (9.997 MΩ), are used in conjunction with components in the signal conditioning circuit for frequency compensation. C3 reduces input noise in the signal path. R100, R101 & R103 provide a current limited connection to voltages that will minimize the leakage current of CR8, CR9 and CR10, which combines with the input signal creating a temperature-dependent error in the reading.

Inductors L1, L2, L4 & L5 attenuate electromagnetic interference (EMI) and capacitive coupled noise that is picked up by the input circuit and test leads that is passed to the signal conditioning circuit.

The operation of R7, R10, R11, R48, C26, C31, CR5 and CR6 is described in “Secondary Analog Circuits”.

Analog Signal Conditioning

U1 provides the switching that is necessary for range selection, the operational amplifiers that are used for buffering and filtering, various current source values and various voltage comparator functions, which are required to transform the input signal to a representation that can be measured and quantified.

VAC

The V/Ohms input is connected, as described in Table 11, to DIV_A (U1 pin 3) and routed by U1 internal switches to the inverting input of an internal operational amplifier. The overall gain to ACAMP_O (U1 pin 22) is set by the total resistance to the inverting input from the V/Ohms input, the selected range resistor in Z1, R105, R12 and R8. U1 works in conjunction with C43 & R94 to compensate the frequency response of this path. The signal at ACAMP_O is, therefore, a scaled representation of the AC input signal

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VDC

mVDC

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 LowPass 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. If the Hz function is selected, the 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.

The V/Ohms input is connected, as described in Table 11, to DIV_A (U1 pin 3) and routed by U1 internal switches to one of the other resistors in the Z1 network to be divided. The divided voltage is filtered, buffered and passed to FE_O (U1 pin19) ready for measurement. If the operator selects the Hz function, the signal is routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency or duty cycle measurement.

The V/Ohms input is connected, as described in Table 11, to SENSE_HI (U1 pin 1) and routed by U1 internal switches to be filtered, buffered and passed to FE_O (U1 pin19) ready for measurement. The resistor Z1 (9.997 MΩ), is used to provide a 10 MΩ impedance across the Meter V/Ohms to COMMON input jacks by connecting DIV_A (U1 pin 3) to R3 (U1 pin 9), which in turn is connected to COMMON by Z1 (440.4 Ω) and R8. This connection is opened by U1 when the HiZ input power up option is selected. If the operator selects the Hz function, the signal is routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency or duty cycle measurement.

Temperature

The V/Ohms input is connected the same as in mVDC to FE_O (U1 pin 19) with the exception that U1 provides a gain of 10 to the signal. Another measurement of the temperature of the input terminals where the thermocouple wire transitions to copper is required to calculate the actual temperature sensed by a thermocouple. Since U1 is controlled by the microprocessor, this measurement is done by routing two different values of current from the U1 current source via RJT_I (U1 pin 35) to Q3 and the resulting VBE is routed, buffered and passed to the FE_O (U1 pin 19) ready for measurement. The reference junction temperature is calculated from these measurements. Inductor L2 and capacitor C2 keep noise out of the measurement circuitry. Since thermocouples are easily broken and give incorrect readings, a periodic test of the thermocouple is required. A current from the U1 current source is routed to ISRC (U1 pin36) and on to the thermocouple that is connected from V/Ohms to COMMON. The resulting voltage drop across the thermocouple is connected to the U1 internal comparators and converted to a digital signal at COMP_O (U1 pin 24) ready for evaluation by the microprocessor.

Ohms Below the 6 MΩ 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 SENSE_HI (U1 pin 1) via the components indicated in Table 11. SENSE_HI is routed by U1 internal switches, filtered, buffered and passed to FE_O (U1 pin19) ready for measurement. Resistor R51 sets the reference for the 1 mA and 100 µA U1 current-source currents. Resistor R52 sets the reference for the 10 µA, 1 µA and 0.5 µA U1 current source currents. Capacitors C4 and C5 are used by the U1 current source charge pump to set the available compliance voltage at ISRC to

7.5 V with respect to COMMON. The 0.5-µA current source is not used for resistor measurements in these ranges. If the operator selects the Hz function, the signal is

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. DIV_A is routed by U1 internal switches to R0 (U1 pin 5) and on to Z1 (1.106 MΩ) to divide the sensed voltage by 10. The divided voltage is filtered, buffered with a gain of two, and passed to FE_O (U1 pin19) ready for measurement. Only the 1 µA and

0.5 µA current sources are used in these ranges. If the operator selects the Hz function, the signal is routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency or duty cycle measurement.

Continuity in all Ohms and the Siemens Ranges

The same measurement paths discussed above apply with the exception that the filtering is turned off to speed up the circuit response and the signal at FE_O (U1 pin 19) is routed to U1 comparators, which convert it to a digital signal at CONT_O (U1 pin 24) ready for evaluation by the microprocessor.

Capacitance

The U1 current source is enabled and internally routed to COMMON. ISRC (U1 pin 36) is routed to the V/Ohms input, which is also connected to SENSE_HI (U1 pin 1) via the components indicated in Table 11. The voltage signal at SENSE_HI is internally routed in U1 to the comparators converted to a digital signal at COMP_O (U1 pin 24) ready for evaluation by the microprocessor, buffered and passed on to FE_O (U1 pin 19) ready for measurement. The capacitor is discharged to below a value set on the comparator via ISRC (U1 pin 36), which is connected to COMMON or the negative voltage rail depending on how much voltage is on the capacitor being measured. Once the capacitor is discharged sufficiently, current is applied to it in accurately measured packets until the U1 comparator signals that the capacitor under test has been sufficiently charged. By measuring the voltage at discharge and after charge the value of the capacitor is calculated by the microprocessor.

Diode Test

The U1 1-mA current source is enabled and routed to ISRC (U1 pin 36) and on to the V/Ohms input, which is also connected to SENSE_HI (U1 pin 1) via the components indicated in Table 11. SENSE_HI is routed by U1 internal switches to R1 (U1 pin 7) and on to Z1 (110.01 kΩ) & R8 which form 10-to-1 divider with Z2. The divided voltage signal is filtered, buffered with a gain of two and passed to FE_O (U1 pin19) ready for measurement.

mA, µA and AAC

The mA/µA input and the A input are connected to R4 (U1 pin 10) as described in Table

11. The voltage at R4 is proportional to the product of the current being measured and the shunt resistance that is in use. The voltage at R4 is routed by U1 internal switches to the inverting input of an internal operational amplifier. The overall gain to ACAMP_O (U1 pin 22) is set by the total resistance from the shunt in use to the inverting input, either resistor Z1(1.106 MΩ) or Z1(110.01 kΩ), R105, R12 & R8. The signal at ACAMP_O is, therefore, a scaled representation of the AC current input signal. The signal at ACAMP_O is routed to either the Low-Pass Filter or the RMS Converter or both using multiplexer U12. The output of the Low-Pass Filter or the RMS Converter is routed back into CONV_IN (U1 pin13), filtered, buffered with a gain of two and passed to FE_O (U1 pin 19) ready for measurement. If the operator selects the Hz function, the

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mA, µA and ADC

Active Filter

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.

The mA/µA input and the A input are connected to R4 (U1 pin 10) as described in Table

11. The voltage at R4 is proportional to the product of the current being measured and the shunt resistance that is in use. The voltage at R4 is routed by U1 internal switches, filtered, buffered with a gain of 1 or 10 depending upon the range selected and passed to FE_O (U1 pin 19) ready for measurement. If the Hz function is selected, the signal at FE_O is also routed within U1 to comparators that will produce a digital signal at COMP_O (U1 pin 24) ready for frequency or duty-cycle measurement.

The U1 buffer amplifier connected to FE_O (U1 pin 19) is zeroed digitally by the microprocessor. The voltage at ZERO_IN (U1 pin 14) is routed by U1, buffered with the selected gain and passed on to FE_O ready for measurement.

C9, C10, R17 & R18 are used in conjunction with an operational amplifier internal to U1 to form a low-pass active filter. This configuration produces the equivalent of two cascaded filters, each at approximately 6 Hz. R18 is bypassed by switches in U1 when the input impedance of the range voltage divider is above 1 MΩ.

800 Hz Low Pass Filter

R86, R87, R88, C36, C37, C38 & U4 form an 800-Hz low-pass filter (three pole Butterworth) that can be selected in the VAC function. This filter is used to stop high frequency noise such as that encountered in motor drive controllers from passing on to the measurement circuits. The A switch of multiplexer U12 is used to select between either the input or output of this filter as an input to the RMS Converter. The B switch of multiplexer U12 can select the output of this filter for input to CONV_IN (U1 pin 13) and bypass the RMS Converter when the Frequency function or pm option is selected.

RMS to DC Converter

C6, U7 & C7 form the RMS-to-DC conversion circuit. C33 & C35 are RF-bypass capacitors. C32 & C34 are power-supply bypass capacitors for U7. R29, R30, R32, R33, Q6 & Q7 form the power-control circuit for U7.

The selected AC signal at the A output of U12 is passed to U7 pin 1 via DC-blocking capacitor C6. U7, with the aid of the averaging capacitor C7 on pin 5, produces a DC output at pin 6 that is proportional to the RMS of the input.

U7 is powered on and off as needed for the selected Meter function by the microprocessor controlling the AC* signal. When AC* is driven to a logic high (+0.8 V), Q6 is turned on, turning on Q7, which connects the positive end of the battery (6 V minimum) to the pin 3 of U7, thereby powering it down. When AC* is driven to a logic low (-2.5 V), transistor Q6 is turned off, turning off Q7, which allows U7 pin 3 to be pulled to +0.8 V through R33, thereby allowing Q7 to power on.

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. Since REF* (compliment of REF) is tied to -2.5 V and both pairs of inputs to U3 are handled differentially, the dynamic range of the VIN is ±1.25 V around COMMOM. The microprocessor U2 uses three digital lines to communicate with U3. U3 signals the microprocessor U2 that a conversion is completed by pulling the SDO signal line to logic low (-2.5 V), which is coupled through current limiting resistor R31 to DOUT. When U2 is ready for the reading, it pulls ADCS* of U3 to a logic low and clocks the data serially out of SDO with the signal ADSCK applied to SCK. Connecting F0 of U3 to -2.5 V sets the internal clock so that the normal mode rejection ratio (NMRR) of the digital filter will provide adequate rejection of both 50 Hz and 60 Hz.

Secondary Analog Circuits

Several secondary analog circuits are used to provide signals to a 12-bit, 200 kilo samples per second (ksps) (8000 sps is the highest rate used) analog to digital converter (ADC) with eight multiplexed-inputs in U2.

R7, R48 C31 & CR5 form a circuit that determines whether a plug is inserted into the mA/µA input jack. The signal MAJACK is held at -2.5 V via R48 if the split-jack J1 is not shorted by a plug. When a plug shorts split-jack J1, current will flow through R7 and the MAJACK signal is pulled to near COMMON via R28 or R4 and/or R5. MAJACK is measured by U2 to determine if the function selected by the rotary switch S1 is in conflict with the Meter inputs. C31 suppresses high frequency noise. Diode CR5 provides protection in case F1 is open. R10, R11, C26 & CR6 provide the same function for the

A input with the COMMON connection via R6.

Keypad

R97 & R98 allow the Meter model and possible revision number to be read by the microprocessor U2 as an analog signal over the single signal path MODEL.

R34, R35, R36, R37, C56 & U4 form a buffer and analog level shifter for allowing the ADIN signal to be sampled by the faster U2 ADC. This ADC is used for auto-ranging, for bar graph readings and p m. R34 and R35 set the DC gain at the output of U4 to 2. Since the dynamic range of ADIN is ±1.25, the signal at the U4 output is ±2.5 V. Since R36 and R37 form a voltage divider referenced to -2.5V, the signal at FASTADIN has a dynamic range of -2.5V to 0 V with respect to COMMON. C56 provides a band-limited response to the higher frequencies contained in signals that are being evaluated for p m. C39 bypasses U4 power supplies.

S1, R22, R53, R54, R55, R58, R59, R60, R61, R84 & C20 allow the position of the rotary switch S1 to be read by the microprocessor U2 as an analog signal over the signal path SWPOS. U2 reads the position of S1 by pulling the SWPWR signal to logic high (+0.8V) and reading the signal at SWPOS. The voltage divider formed by R61, R60, R59, R58, R55, R54, R53 & R84 creates a signature voltage for each switch position of S1. R22 will pull this voltage down slightly when the divider taps are connected, but will pull the SWPOS voltage to -2.5 V when S1 is between switch positions. C20 suppresses noise.

R15 & R16 form a voltage divider to allow the battery voltage to be monitored via signal LOWBATT. C28 suppresses noise.

R40, R43, R68, S3, S4, S5, S6, S7, S8, S9, S10 & S11 form the buttons that allow access to Meter functions that are not selected by rotary switch S1. The microprocessor U2 is connected to 9 switches with three strobe lines PB4, PB5 & PB6 to three switches each. The other end of each switch is pulled to +0.8 V by R40, R43 or R68 and connected to

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Microprocessor & Support Circuits

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.

U2 is the microprocessor and Y1 is the crystal used for the clock generator that is internal to U2. The 32.768-kHz oscillator is multiplied to above 1 MHz inside U2 when the Meter is not in sleep mode. This low oscillator frequency helps reduce the standby power required by U2 while the Meter is in sleep mode. C17, C18, C19, C25, C27 & C29 are power supply bypass capacitors.

R21 & C8 form the power on reset circuit that holds the RST* signal to U2 at logic low until C8 is charged to logic high on the way to 3.3 V (-2.5 V to +0.8 V).

U14 is an AND gate that allows the signal ODCMP from COMP_O (U1 pin 24) to gate the SMCLK signal from U2 back to the DCMP input of U2 to facilitate the measurement of duty cycle. When U2 sets SMCLK to logic high (+0.8 V), the ODCMP signal is counted by U2 and frequency is measured. When U2 drives SMCLK with an approximately 1-MHz clock, this signal appears at DCMP only when ODCMP is logic high (+0.8 V). The frequency of the signal ODCMP is measured directly while the multiple positive periods are measured referenced to the SMCLK. U2 uses the frequency of ODCMP and the accumulated time that the signal was high to compute both the positive and negative duty cycle.

LCD

U11 is a liquid crystal display (LCD) with four back planes that are multiplexed by U2 with the COM0-3 signals. Only 34 of the possible 40 segment drivers of U2 are connected to U11 and not all combinations of segments and back planes are used.

R20, R25, R26, R27, R41 & RT2 form a temperature-compensated voltage divider used to generate the four voltage levels used by the display multiplexer internal to U2. As the temperature of the Meter is increased, U11 requires less total voltage to maintain the desired contrast ratio. RT1 is a negative temperature coefficient device, so as the temperature increases the total current through R27 increases and the voltage across R20, R25 & R26 decreases, thereby maintaining the display contrast ratio. The opposite occurs as the temperature lowers.

Backlight

DS3, R14, R46, R50, R96, R99, Q4, Q8 & Q17 form the backlight and backlight control circuit. The microprocessor holds the backlight off or can turn it on with two levels of intensity available. When the BKLT and HIBEAM signals from U2 are at logic low (-2.5 V), Q4, Q8 & Q17 are off, allowing no current to flow through DS3. When U2 drives BKLT to logic high (+0.8 V), Q4 & Q8 are turned on. The current through DS3 is set by R50, R96 and Q8, and regulated by Q4, which adjusts the base current of Q8 to keep the voltage drop across R50 & R96 equal to the voltage drop across R46. When U2 drives HIBEAM to logic high (+0.8 V), Q17 is turned on and partially bypasses R96, thereby requiring more current through R50 to keep the voltage across R50, R96 and Q17 equal to the drop across R46 resulting in a brighter backlight.

Beeper

LS1, R19, R44, R47, R108, C11, Q5 & U5 form the beeper and beeper control circuit. When the BPR signal from U2 is at logic low (-2.5 V), Q5 is off, which disconnects the negative power supply connection of U5 disabling the beeper oscillator and drive circuit. When the BPR signal from U2 is at logic high (+0.8 V), Q5 is on, which allows U5 to power up. Pin 2 of piezoelectric beeper LS1 is driven by the parallel combination of two U5 inverters and pin 1 of LS1 is driven by two more U5 inverters to supply enough

Digital Multimeter

current to the beeper and ensure adequate loudness. R108 allows for limiting beeper current if necessary due to future component changes. R44 in parallel with R47 & C11 set the frequency of the beeper oscillator (note that the junction of R44, R47 & C11 operates at voltages beyond the power supply values). The remaining two U5 inverters are used in series to form the non-inverting buffer portion of the oscillator.

Troubleshooting

Refer to the “Theory of Operation” and “Schematics” sections to assist in troubleshooting the Meter.

Restoration Actions

Refer to “Performance Tests”.

Basic Maintenance

XWWarning

To avoid possible electric shock or personal injury:

• Remove the test leads and any input signals before opening

the case or replacing the battery or fuses.

• Repairs or servicing covered in this manual should be

performed only by qualified personnel.

Cleaning the Meter

To avoid possible electric shock, personal injury, or damage to the meter, never allow water inside the case.

To avoid damaging the Meter, never apply abrasives, solvents, aromatic hydrocarbons, chlorinated solvents, or methanolbased fluids to the 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. Such contamination may be dislodged by turning the Meter over and, with all test leads removed, gently tapping on the case.

Thoroughly clean the terminals as follows:

1. Turn the Meter off and remove all test leads.

2. Soak a clean swab with isopropyl alcohol and work the swab around in each input terminal to remove contaminates.

XWWarning

WCaution

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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. Disconnect test leads from any live source, turn the rotary knob to OFF, and remove the test leads from the front terminals.

2. Remove the battery door by using a flat-blade screwdriver to turn the battery door screws 1/4-turn counterclockwise.

3. The case bottom is secured to the case top by three screws and two internal snaps (at the LCD end). Using a Phillips-head screwdriver, remove the three screws.

WCaution

To avoid damaging the Meter, the gasket that is sealed to the bottom case, and is between the two case halves, must remain with the case bottom. The case top lifts away from the gasket easily. Do not damage the gasket or attempt to separate the case bottom from the gasket.

4. Hold the Meter display side up.

5. Pushing up from the inside of the battery compartment, disengage the case top from the gasket.

6. Gently unsnap the case top at the display end, see Figure 2.

Figure 2. Opening the Meter, Battery and Fuse Replacement

ama12.eps

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. Remove the top shield assembly that also houses the LCD and lightpipe for the LCD backlight.

3. To access the LCD, unsnap the LCD mask using a small flat-blade screwdriver. The LCD may now be removed. Refer to Figure 3.

Note

Two elastomeric connectors make electrical contact between the LCD and the PCA. These connectors usually stick to the LCD when it is removed. If the connectors are to be reused, do not handle them, as the electrical contact points might become contaminated. Use tweezers to remove these connectors.

4. To reinstall the connectors, replace the LCD and LCD mask and lay the top shield face down. Install the elastomeric connector strips into the slots on the top shield.

5. Place the PCA onto the top shield so that the screw holes align.

6. Place the bottom shield onto the PCA and secure the assembly with five Phillipshead screws. Ensure that the shields are tightly attached. Properly fitted shields are required for the Meter to perform to specifications.

LCD Mask

LCD

Figure 3. Removing LCD Mask to Access LCD

ama08f.eps

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Reassembling the Meter Case

To reassemble the Meter case:

1. Verify that the rotary knob and circuit board switch are in the the gasket remains secured to the bottom case.

2. Place the PCA into the bottom case.

3. Place the case top on the case bottom.

4. To avoid damaging the battery wire, ensure the wire exits the middle of the battery compartment.

5. Properly seat the case gasket and snap the case halves together above the LCD end. See Figure 2.

6. Reinstall the three case screws and the battery door.

7. Secure the battery door by turning the screw 1/4-turn clockwise.

8. Go to “Performance Tests” later in this document, and perform the procedures described.

Replacing the Battery

Replace the battery with a 9-V battery (NEDA A1604, 6F22, or 006P).

To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator (b) appears. If the display shows “bAtt” the Meter will not function until the battery is replaced.

OFF position, and that

XWWarning

Replace the battery as follows, refer to Figure 2:

1. Turn the rotary knob to OFF and remove the test leads from the terminals.

2. Remove the battery door by using a standard-blade screwdriver to turn the battery door screws one-quarter turn counterclockwise.

3. Remove the old battery and replace it with a new one.

4. Align the battery leads so that they not pinched between the battery door and the case bottom.

5. Secure the door by turning the screws one-quarter turn clockwise.

Testing Fuses and Current Circuitry

If a test lead is plugged into the mA/µA or A terminal and the rotary knob is turned to a non-current function, the Meter chirps and flashes “LEAd” if the fuse associated with that current terminal is good. If the Meter does not chirp or flash “LEAd”, the fuse is bad and must be replaced. Refer to Table 17 for the appropriate replacement fuse.

Before measuring current, test the quality of the appropriate fuse and the current shunt using the following procedure. See Figure 4.

1. Turn the rotary knob to N.

2. To test F2, insert a test lead into the I input terminal and touch the probe to the A input terminal.

The input receptacles contain split contacts. Be sure to touch the probe to the half of the receptacle nearest the LCD.

Note

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. The display should read between 0.995 kΩ and 1.005 kΩ. If the display reads OL, replace the fuse and test again. If the display reads another value, further servicing is required.

XWWarning

To avoid electrical shock or personal injury:

• Remove the test leads and any input signals before

replacing the battery or fuses.

• Install ONLY specified replacement fuses with the

amperage, voltage, and speed ratings shown in Table 17.

TRUE RMS MULTIMETER

MIN MAX

Peak MIN MAX

4½ DIGITS

1 Second

LOLO

OFF

AmACOM

10A MAX

FUSED

˚C/˚

AutoHOLD

RANGE

Hz %

REL

mA A

400mA FUSED

Good F2 fuse: 00.0 Ω to

00.5 Ω

Replace fuse: OL

Touch top half

of input contacts

Replacing the Fuses

To replace the fuse(s), perform the following procedure.

1. To open the Meter, refer to “Opening the Meter Case”. See Figure 2.

2. Grasp the fuse in the center with needle nose pliers. Pull straight up on the fuse

to remove it from the fuse clips.

3. Install ONLY specified replacement fuses with the amperage, voltage, and speed

ratings shown in Table 17.

4. To close the Meter, refer to “Reassembling the Meter Case”.

Good F1 fuse: 0.995 kΩ to

1.005 kΩ

Replace fuse: OL

Figure 4. Testing the Current Input Fuses

MIN MAX

Peak MIN MAX

4½ DIGITS

1 Second

LOLO

OFF

AmACOM

10A MAX

FUSED

TRUE RMS MULTIMETER

400mA FUSED

˚C/˚

AutoHOLD

RANGE

Hz %

REL

mA A

aom5f.eps

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.

• Repairs or servicing should be performed only by qualified

personnel.

Table 13. Required Equipment

Equipment Required Characteristics Recommended Model

Calibrator AC Voltage Range: 0 - 1000 V ac

Accuracy: ± 0.12 % Frequency Range: 60 - 20000 Hz Accuracy: ± 3 %

DC Voltage Range: 0 - 1000 V dc Accuracy: ± 0.012 %

Current Range: 350 µA - 2 A Accuracy: AC (60 Hz to 1 kHz): ± 0.25 % DC: ± 0.05 %

Frequency Source: 19.999 kHz - 199.99 kHz Accuracy: ± 0.0025 % Amplitude: 150 mV to 6V rms Accuracy: ± 5 %

Range: 1 Ω - 100 MΩ

Accuracy: 0.065 %

TC Adapter Accessory K-type Fluke 80 AK

K-type Thermocouple K-type, mini-plug on both ends

Fluke 5500A Multi-Product Calibrator or equivalent

Performance Tests

The following performance tests verify the complete operability of the Meter and check the accuracy of each Meter function against the Meter’s specifications. Performance tests should be performed annually to ensure that the Meter is within accuracy specifications.

Accuracy specifications are valid for a period of one year after calibration adjustment, when measured at an operating temperature of 18 °C to 28 °C and at a maximum of 90 % relative humidity.

To perform the following tests, it is not necessary to open the case. No adjustments are necessary. Make the required connections, apply the designated inputs, and determine if the reading on the Meter display falls within the acceptable range indicated.

Note

If the Meter fails any of these tests, it needs calibration adjustment or repair.

Digital Multimeter

pears in low pass filter mode. Also appears

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.

Number Feature Indication

Polarity indicator for the analog bar graph.

Figure 5. Display Features

Table 14. Display Features

Hi Res

TrigY

B X C W D g

Positive or negative slope indicator for Hz/duty cycle triggering.

The continuity beeper is on.

Relative (REL) mode is active.

Smoothing is active.

aom1_af.eps

G H I

m MAX

MIN AVG

Indicates negative readings. In relative mode, this sign indicates that the present input is less than the stored reference.

Indicates the presence of a high voltage input. Appears if the input voltage is 30 V or greater (ac or dc). Also ap in cal, Hz, and duty cycle modes.

AutoHOLD is active.

Display Hold is active. Indicates the Meter is in Peak Min Max mode and the response time is 250 µ

Indicators for minimum-maximum recording mode.

Low pass filter mode.

87 V/AN

terminal and the selected

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.

N O

A, µA, mA

V, mV

µF, nF

e, Me, ke

Hz, kHz

AC DC

°C, °F

610000 mV

HiRes

Auto

Manual

Amperes (amps), Microamp, Milliamp

Volts, Millivolts

Microfarad, Nanofarad

Nanosiemens

Percent. Used for duty cycle measurements.

Ohm, Megohm, Kilohm

Hertz, Kilohertz

Alternating current, direct current

Degrees Celsius, Degrees Fahrenheit

Displays selected range

The Meter is in high resolution (Hi Res) mode. HiRes=19,999

The Meter is in autorange mode and automatically selects the range with the best resolution.

The Meter is in manual range mode.

The number of segments is relative to the full-scale value of the selected range. In normal operation 0 (zero) is on the left. The polarity indicator at the left of the graph indicates the polarity of the input. The graph does not operate with the capacitance, frequency counter functions, temperature, or peak min max. For more information, see “Bar Graph”. The bar graph also has a zoom function, as described under "Zoom Mode".

bAtt diSC EEPr

Err CAL

Err

LEAd

Overload condition is detected.

Error Messages

Replace the battery immediately.

In the capacitance function, too much electrical charge is present on the capacitor being tested.

Invalid EEPROM data. Have Meter serviced.

Invalid calibration data. Calibrate Meter.

WTest lead alert. Displayed when the test leads are in the A or mA/µA rotary switch position does not correspond to the terminal being used.

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.

Table 15. Accuracy Tests

Step Test Function Range 5500A Output Display Reading

1 600 mV 330 mV, 60 Hz 327.3 to 332.7 2 600 mV 600 mV, 13 kHz 586.0 to 614.0 3 6 V 3.3 V, 60 Hz 3.275 to 3.325 4 6 V 3.3 V, 20 kHz 3.214 to 3.386 5 60 V 33 V, 60 Hz 32.75 to 33.25 6 60 V 33 V, 20 kHz 32.14 to 33.86 7 600 V 330 V, 60 Hz 327.5 to 332.5 8 600 V 330 V, 2.5 kHz 323.0 to 337.0 9 1000 V 500 V, 60 Hz 494 to 506 10 11 600 mV 150 mV, 99.95 kHz 99.93 to 99.97 12

13 6 V 0.7 V, 99.95 kHz 99.93 to 99.97 14 15 V Hz

17 6V 3.3 V dc 3.297 to 3.303 18 60 V 33 V dc 32.97 to 33.03 19 600 V 330 V dc 329.7 to 330.3 20 21 600 mV 33 mV dc 32.9 to 33.1 22 23 600 Ω 330 Ω ( Use 2 wire Comp)1 329.1 to 330.9 24 6 kΩ 3.3 kΩ (Use 2 wire Comp) 1 3.292 to 3.308 25 60 kΩ 33 kΩ 32.92 to 33.08 26 600 kΩ 330 kΩ 327.9 to 332.1 27 6 MΩ 3.3 MΩ 3.279 to 3.321 28

AC Volts

AC Volts Frequency

Sensitivity

Trigger level

V Hz

Duty Cycle

DC Volts

DC Volts e

Ohms

1000 V 1000 V, 1 kHz 986 to 1014

600 mV 150 mV, 199.50 kHz 199.48 to 199.52

60 V 7 V, 99.95 kHz 99.93 to 99.97 6 V 3.4 V, 1 kHz Sq. Wave 999.8 to 1000.2

6 V 5 V, 1 kHz, DC offset 2.5 V

Sq. Wave

1000 V 1000 V dc 998 to 1002

600 mV 330 mV dc 329.6 to 330.4

50 MΩ 30 MΩ 29.67 to 30.33

49.7 % to 50.3 %

87 V/AN

Service Manual

Table 15. Accuracy Tests (cont.)

Step Test Function Range 5500A Output Display Reading

1. Or short test leads and use REL to offset test lead resistance.

2. Remove test leads from unit.

3. To ensure accurate measurement, the Meter and thermocouple adapter must be at the same temperature. After connecting the thermocouple adapter to the Meter allow for reading to stabalize before recording display reading.

4. The Meter accuracy is not specified at this input signal frequency with Low-pass filter selected. The display reading shown, check that the Low-pass filter is active and follows an expected roll-off curve.

5. Use REL to compensate for internal Meter and lead capacitance. The test leads must be disconnected from the calibrator before pushing REL.

Conductance

Diode

AC Amps

DC Amps

AC Milliamps

DC Milliamp

AC Microamps

DC Microamps

E Capacitance

Low Pass Filter

Peak Min/Max

Temperature

Backlight

60 nS Open input -0.10 to 0.10 60 nS 100 MΩ 9.80 to 10.20

6 V 3.0 V dc 2.939 to 3.061

6 A 3.0 A, 60 Hz 2.968 to 3.032

6 A 3.0 A 2.990 to 3.010

60 mA 33 mA, 60 Hz 32.65 to 33.35

400 mA 330 mA, 60 Hz 326.5 to 333.5

60 mA 33 mA 32.89 to 33.11

400 mA 330 mA 329.1 to 330.9 600 µA 330 µA, 60 Hz 326.5 to 333.5

6000 µA 3300 µA, 60 Hz 3265 to 3335

600 µA 330 µA 328.9 to 331.1 6000 µA 3300 µA 3291 to 3309

10 nf Open input2 0.21 to 0.31

100 nf 5 nf5 4.7 to 5.3 100 µf 9.5 µf 9.2 to 9.8

1000 V 400 V, 400 Hz 372 to 408

1000 V 400 V, 800 Hz

6 V

0 °C -1.0 to 1.0

100 °C 98.0 to 102.0

Press backlight button Backlight comes on

Press backlight button Backlight Intensifies

Press backlight button Backlight off

8 Vpp, 2 kHz Sq. Wave, DC offset 2 V

226 to 3404

Max = 5.896 to 6.104

Min = -1.898 to -2.102

Digital Multimeter

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. Perform the Calibration Adjustment Procedure should the Meter fail any performance test listed in Table 15.

Calibration Adjustment Counter

The Meter contains a calibration adjustment counter. The counter is incremented each time a Calibration Adjustment Procedure is completed. The value in the counter can be recorded and used to show that no adjustments have been made during a calibration cycle.

Use the following steps to view the Meter's calibration counter.

1. While holding down B, turn the rotary knob from OFF to VAC. The Meter should display “Z CAL”.

2. Press D once to see the calibration counter. For example "n001".

3. Turn the rotary knob to OFF.

Calibration Adjustment Password

To start the Calibration Adjustment Procedure, the correct 4-button password must be entered. The password can be changed or reset to the default as described in following paragraphs. The default password is “1234”.

Changing the Password

Use the following steps to change the Meter's password:

1. While holding down B, turn the rotary knob from OFF to VAC. The Meter displays “Z CAL”.

2. Press D once to see the calibration counter.

3. Press D again to start the password entry. The Meter displays "????".

4. The Meter buttons represent the digit indicated below when entering or changing the password:

A = 1 B = 2 C = 3 D = 4 H = 5 E = 6 F = 7 G = 8

Press the 4 buttons to enter the old password. If changing the password for the first time, enter A (1) B (2) C (3) D (4).

5. Press C to change the password. The Meter displays "----" if the old password is correct. If the password is not correct, the Meter emits a double beep, displays "????" and the password must be entered again. Repeat step 4.

6. Press the 4 buttons of the new password.

7. Press D to store the new 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”.

2. Remove the Meter's top case. Leave the PCA in the bottom case. (See “Opening the Meter Case”.)

XWWarning

To avoid electrical shock or personal injury, remove the test leads and any input signal before removing the Meter's top case.

3. Through an access hole provided in the top shield, short across the keypads on the PCA. See Figure 6. The Meter should beep. The default password is now restored.

4. Replace the Meter's top case and turn the rotary knob to OFF. (See “Reassembling the Meter Case).

Access Hole For PCA Keypad

Figure 6. Restoring the Default Password

ama01f.eps

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. The measurement value is not calibrated so it may not match the input value. This is normal.

B Press and hold to display the required input amplitude. G Press and hold to display the frequency of the required input.

Press to store the calibration value and advance to the next step. This button

is also used to exit calibration mode after the calibration adjustment sequence is complete.

Calibration Adjustment Procedure

Use the following steps to adjust the Meter's calibration. If the Meter is turned off before completion of the adjustment procedure, the calibration constants are not changed.

1. While holding down B, turn the rotary knob from OFF to VAC. The Meter displays “Z CAL”.

2. Press D once to see the calibration counter.

3. Press D again to start the password entry. The Meter displays "????".

4. Press 4 buttons to enter the password.

5. Press D to go to the first calibration step. The Meter displays "C-01" if the password is correct. If the password is not correct, the Meter emits a double beep, displays "????" and the password must be entered again. Repeat step 4.

6. Using Table 16, apply the input value listed for each calibration adjustment step. For each step, position the rotary switch and apply the input to the terminals as indicated in the table.

7. After each input value is applied, press D to accept the value and proceed to the next step (C-02 and so forth).

Note

After pressing D, wait until the step number advances before changing the calibrator source or turning the Meter rotary knob.

If the Meter rotary knob is not in the correct position, or if the measured value is not within the anticipated range of the input value, the Meter emits a double beep and will not continue to the next step.

Some adjustment steps take longer to execute than others (10 to 15 seconds). For these steps, the Meter will beep when the step is complete. Not all steps have this feature.

8. After the final step, the display shows "End" to indicate that the calibration adjustment is complete. Press D to go to meter mode.

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.

Table 16. Calibration Adjustment Steps

Switch Position

(Function)

(AC Volts)

(DC Volts)

(DC Millivolts)

Ω

(Ohms)

Input

Terminal

Calibration Adjustment

Step

C-01 600.0 mV, 60 Hz C-02 600.0 mV, 20 kHz C-03 6.000 V, 60 Hz C-04 6.000 V, 20 kHz C-05 60.00 V, 60 Hz C-06 60.00 V, 20 kHz C-07 600.0 V, 60 Hz C-08 600.0 V, 10 kHz C-09 6.000 V, 0 Hz C-10 60.00 V, 0 Hz C-11 600.0 V, 0 Hz C-12 600.0 mV, 0 Hz C-13 60.00 mV, 0 Hz C-14 600.0 Ω C-15 6.000 kΩ C-16 60.00 kΩ C-17 600.0 kΩ C-18 6.000 MΩ C-19 0.000 Ω C-20 50.0 MΩ

Input Value

O (Diode Test)

A, mA

(Amps, milliamps)

(Microamps)

mA /UA

C-21 3.000 V, 0 Hz

C-22 6.000 A, 60 Hz C-23 6.000 A , 0 Hz C-24 60.00 mA, 60 Hz

C-25 400.0 mA, 60 Hz C-26 60.00 mA, 0 Hz C-27 400.0 mA, 0 Hz

C-28 600.0 µA, 60 Hz C-29 6000 µA, 60 Hz C-30 600.0 µA, 0 Hz C-31 6000 µA, 0 Hz

Digital Multimeter

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

Designator

A1 PCA Main Assembly 2174143 89536 2174143 1 AC72 Alligator Clip, Black 1670652 89536 1670652 1 AC72 Alligator Clip, Red 1670641 89536 1670641 1 BT1 Battery, 9 V 2139179 83740 522VP 1 BT2 Cable Assy, 9 V Battery Snap 2064217 89536 2064217 1 CR6 Lightpipe 2074057 89536 2074057 1 F1W Fuse, 0.440 A, 1000 V, FAST 943121 0FB96 DMM-44/100 1 F2 W Fuse, 11 A, 1000 V, FAST 803293 0FB96 DMM-11 1 H2-4 Screw, Case 832246 89536 832246 3 H5-9 Screw, Bottom Shield 448456 89536 448456 5 J1-2 Elastomeric Connector 817460 89536 817460 2 MP2 Shield, Top 2073906 89536 2073906 1 MP4 Shield, Bottom 2074025 89536 2074025 1 MP5 Case Top (PAD XFER) with Window 2073992 89536 2073992 1 MP6 Case Bottom 2073871 89536 2073871 1 MP8 Knob, Switch (PAD XFER) 2100482 89536 2100482 1 MP9 Detent, Knob 822643 89536 822643 1 MP10-11 Foot, Non-Skid 824466 89536 824466 2 MP13 Shock Absorber 828541 89536 828541 1 MP14 O-Ring, Input Receptacle 831933 17506 5-143-N1472-70 1 MP15 Holster w/ Tilt Stand 2074033 89536 2074033 1 MP22 Battery Door 2073938 89536 2073938 1 MP27-MP30 Contact RSOB 1567683 89536 1567683 4 MP31 Mask, LCD (PAD XFER) 2073950 89536 2073950 1 MP41 Housing, RSOB 2073945 89536 2073945 1 MP390-391 Access Door Fastener 948609 89536 948609 2 NA Tiltstand 2074040 89536 2074040 1 S2 Keypad 2105884 89536 2105884 1 TL75 Test Lead Set 855742 89536 855742 1 TM1

(not shown) TM2

(not shown) TM3

(not shown)

80BK

WTo ensure safety, use exact replacement only.

CD ROM, 87 V/AN 2153570 89536 2153570 1

87 V/AN Users Manual 2153581 89536 2153581 1

87 V/AN Service Manual (this manual) 2153596 89536 2153596 1

LCD, 4.5 DIGIT,TN, Transflective, Bar Graph, OSPR80

Thermocouple Assembly, K-Type, Beaded, Molded Dual Banana Plug, Coiled

Description

Part

Number

2065213 89536 2065213 1

1273113 89536 1273113 1

Cage

Manufacturer’s

Part Number

Qty

87 V/AN

Service Manual

MP5

MP8

MP6

H1 (4)

BT1

H5, 6

MP8

MP31

CR6

MP4

MP2

MP1

MP22

Holster

MP15

Figure 7. 87 V/AN Final Assembly

TL75

Test Lead Set

Tilt Stand

AC72 (Option)

Alligator Clips

axp015.eps

Digital Multimeter

Table 18. A1 Main PCA

Service and Parts

Reference

Designator

C2 C39 C57

C3 C4-5 C8 C12

C14 C19-21 C25 C28

C9-10

C11

C15

C16

C17 C18 C22 C27

C29 C26 C31

C32-35

C36

C37

C38

C43

C50

C56

CR1 CR3

CR2

CR5-6 CR8-10

DS3

J1 INPUT RCPT ASSY 826214 89536 826214 1

L2 L4

Q13

CAPACITOR,FILM,POLYESTER,0.022UF, +-10%,1000V,10MM LS RADIAL,BULK CAPACITOR, SMR,CAP,CER,0.01UF, +-10%,50V,X7R,0603 CAPACITOR, SMR,CAP,CER,180PF, +-5%,100V,C0G,0805

CAPACITOR,CERAMIC,0.1UF, +-10%,25V,X7R,0805,TAPE

CAPACITOR,ELECTROLYTIC,TANTALUM, 22UF,+-10%,6V,3216,TAPE CAPACITOR,ELECTROLYTIC,TANTALUM, 33UF,+-20%,16V,6032,0.300 OHM ESR,TAPE CAPACITOR, FILM,POLYPHENYLENE,0.022UF, +-10%,50V,5750,TAPE CAPACITOR, SMR,CAP,CER,470PF, +-5%,50V,C0G,1206 CAPACITOR, SMR,CAP,TA,4.7UF, +-20%,16V,3528 CAPACITOR,ELECTROLYTIC,TANTALUM, 47UF,+-20%,10V,3528,TAPE CAPACITOR,CERAMIC,0.1UF, +-20%,16V,X7R,0603,TAPE CAPACITOR, SMR,CAP,TA,10UF, +-20%,10V,3528 CAPACITOR, SMR,CAP,CER,0.01UF, +-10%,50V,X7R,1206 CAPACITOR, SMR,CAP,CER,1000PF, +-10%,50V,X7R,0603 CAPACITOR,CERAMIC,2700PF, +-5%,50V,C0G,1206,TAPE CAPACITOR,CERAMIC,390PF, +-5%,50V,C0G,1206,TAPE CAPACITOR, SMR,CAP,CER,6800PF, +-10%,50V,X7R,0805 CAPACITOR,CERAMIC,1.5PF, +0.1PF,1KVAC/DC,COK,5MMLS,RADIAL, BULK CAPACITOR,CERAMIC,100PF, +-5%,100V,C0G,0805,TAPE CAPACITOR SMR,CAP,CER,100PF, +-10%,50V,C0G,1206 DIODE,GF1B SMR,DIODE,SI,100V,1A, DO-214 DIODE,SI,PN,DF01S,100V,1A,BRIDGE, 4 PIN SURFACE MOUNT,3530,TAPE DIODE,SI,PN,BAV199,70V,140MA,3US, DUAL,SERIES,SOT-23,TAPE LED,WHITE,NICHIA NSCW100,310MCD,20MA,4V,IV RANK S-T,COLOR RANK B1-B2,1208,TAPE

CONNECTOR,HEADER, CONNECTOR, 1 ROW, 2MM CTR, VERTICAL PCB MOUNT, 2 PIN, BULK INDUCTOR,BEAD,60 OHMS@100MHZ,6ADC,10MOHM,1806,TAPE INDUCTOR,BEAD,220 OHMS@100MHZ,200MA,0603,TAPE MOSFET,SI,P,IRLML6302,20V,780MA,600 MOHMS,540MW,SOT-23,TAPE

Description

Part

Number

2117948 65964 MMK10223K1000A04L4 1

644838 04222 06035C103KAT2A 3

689588 04222 08051A181JAT1A 1

942529 04222 08053C104KAT3A 10

2053857 04222 TAJA226K006R 1

1614265 31433 T495C336_016AS 1

802501 65964

943365 04222 12065A471JAT1A 1

745976 04222 TAJB475M016R 1

1663963 04222 TAJB476K010R 1

1579869 04222 0603YC104MAT2A 1

603032 04222 TAJB106M010R 4

747261 04222 12061C103KAT1A 2

605342 04222 06035C102KAT2A 4

688986 04222 12065A272JAT1A 1

887278 04222 12065A391JAT1A 1

604238 04222 08055C682KAT1A 1

2138739 89536 2138739 1

601028 04222 08051A101JAT1A 1

740571 04222 12065A101KAT1A 1

912451 24444 GF1B 2

912456 0KTV3 DB104S-T 1

605805 5

2096202 1B1N5

2002420 27264 87553-0210 1

944645 32897

1554422 32897 BLM18AG221SN1D 2

1641929 81483 IRLML6302TR 1

Cage

Manufacturer’s

Part Number

SMC5.7 223K50J31 TR12

NSCW100 (RANK ST,B1-B2)

BLM41PG600SN1D (T/R)

Qty

87 V/AN

Service Manual

Table 18. A1 Main PCA (cont.)

Reference

Designator

Q3 Q6 Q14

Q4-5 Q8 Q17

R7 R10

R11 R48

R12

R14 R99

R15

R16 R29-30 R32

R17-18 R33 R73-74 R80

R19

R20 R25-26 R35-37 R40 R43 R53-55 R58-61 R68 R98

R21 R63

R22 R103

R27

R28

R31

R34 R84

R41

Description

NPN,MMBT3904 SMR,TRANSISTOR,SI,NPN,60V,350MW,SO T-23

TRANSISTOR,SI,NPN,MMBT5089,30V,50M A,50MHZ,200MW,SOT-23,TAPE

TRANSISTOR,SI,PNP,MMBT3906,40V,200 MA,250MHZ,225MW,SOT-23,TAPE

RESISTOR,CERMET COMPOSITION,1K, +-10%,1W,-1300+-300PPM,TAPE

RESISTOR, SMR,RES,CERM,1K, +-5%,1W,200PPM,2512

RESISTOR,CERMET,2K, +-1%,0.1W,100PPM,0805,TAPE

RESISTOR,METAL FILM,110, +-

0.1%,0.25W,25PPM,1210,TAPE RESISTOR, SMR,RES,WW,1,

+-1%,2W,75PPM,1270 RESISTOR,WIREWOUND,0.010,+-

2%,1W,100PPM,RADIAL,BULK RESISTOR, RES,CERM,1M,+-

5%,1W,200PPM RESISTOR,METAL FILM,856,+-

0.5%,0.1W,50PPM,0805,TAPE RESISTOR, SMR,RES,CERM,1M,

+-1%,.125W,100PPM,1206 RESISTOR,CERMET,10M,

+-1%,0.1W,400PPM,0805,TAPE RESISTOR,CERMET,3.01K,

+-1%,0.125W,100PPM,0805,TAPE RESISTOR, SMR,RES,CERM,5.62K,

+-1%,0.1W,100PPM,0805 RESISTOR,CERMET,845K,

+-1%,0.1W,100PPM,0805,TAPE RESISTOR, SMR,RES,CERM,226K,

+-1%,.063W,100PPM,0603 RESISTOR, SMR,RES,CERM,1M,

+-1%,.063W,100PPM,0603 RESISTOR, SMR,RES,CERM,40.2K,

+-1%,.063W,100PPM,0603

RESISTOR, SMR,RES,CERM,100K, +-1%,.063W,100PPM,0603

RESISTOR, SMR,RES,CERM,10K, +-1%,.063W,100PPM,0603

RESISTOR, SMR,RES,CERM,1M, +-1%,0.1W,200PPM,0805

RESISTOR, SMR,RES,CERM,4.32K, +-1%,.063W,100PPM,0603

RESISTOR, SMR,RES,MF,1K, +-0.1%,0.1W,50PPM,0805

RESISTOR, SMR,RES,CERM,49.9K, +-1%,.063W,100PPM,0603

RESISTOR,CERMET,200K, +-1%,0.063W,100PPM,0603,TAPE

RESISTOR, SMR,RES,CERM,21.0K, +-1%,.063W,100PPM,0603

Part

Number

742676 89536 742676 3

820902 65940 SST5089 4

742684 89536 742684 1

1275713 59124 PCF1-102K-T631 <D> 1

601176 18612 CRCW2512-102JR82 1

928742 18612 CRCW-0805-2001F-RT1 1

2064399 59124 RN732ELTD1100B25 1

642790 18612 WSR-2,1-OHM,+-1% 1

2117705 18612 SPU101R01000GD 1

912589 ODBE5 RG1/2-1M-5%(W/LEAD) 2

2093973 59124 RN732ALTD8560D50 1

836387 18612 CRCW-1206-1004F-RT2 1

943659 18612 CRCW-0805-1005F-RT2 2

1591278 18612 CRCW08053011FRT1 1

930110 18612 CRCW-0805-5621F-RT1 2

1292164 18612 CRCW08058453FRT1 1

643871 18612 CRCW-0603-2263FRT1 4

643848 18612 CRCW-0603-1004FRT1 6

689700 18612 CRCW-0603-4022FRT1 1

643863 18612 CRCW-0603-1003FRT1 17

605052 18612 CRCW-0603-1002FRT1 2

928945 18612 CRCW-0805-1004F-RT2 2

605250 18612 CRCW-0603-4321FRT1 1

802469 0DBE5 PCF-W0805R-02-1001-B 1

643921 18612 CRCW-0603-4992FRT1 1

1562307 18612 CRCW06032003FRT1 2

642261 18612 CRCW-0603-2102FRT1 1

Cage

Manufacturer’s

Part Number

Qty

Digital Multimeter

Table 18. A1 Main PCA (cont.)

Service and Parts

Reference

Designator

R44 R47

R46

R50

R51

R52

R85

R86

R87

R88

R94

R96

R100-101

R105

R108

R109

RT1

RT2

RV1-3

Description

RESISTOR, SMR,RES,CERM,475K, +-1%,.125W,100PPM,1206

RESISTOR, SMR,RES,CERM,1K, +-1%,.063W,100PPM,0603

RESISTOR, SMR,RES,CERM,12.1,+1%,0.1W,100PPM,0805

RESISTOR,METAL FILM,24.9K,+-

0.5%,0.063W,50PPM,0603,TAPE RESISTOR,METAL FILM,249K,+-

0.5%,0.063W,50PPM,0603,TAPE RESISTOR, SMR,RES,CERM,49.9K,

+-1%,0.1W,100PPM,0805 RESISTOR, SMR,RES,CERM,102K,

+-1%,.063W,100PPM,0603 RESISTOR, SMR,RES,CERM,107K,

+-1%,0.1W,100PPM,0805 RESISTOR,CERMET,97.6K, +-

1%,0.063W,100PPM,0603,TAPE RESISTOR SMR,RES,CERM,499K,+-

1%,.125W,100PPM,1206 RESISTOR, SMR,RES,CERM,32.4,

+-1%,0.1W,100PPM,0805 RESISTOR, SMR,RES,CERM,499K,

+-1%,0.1W,100PPM,0805 RESISTOR, SMR,RES,CERM,2.8K,

+-1%,.063W,100PPM,0603 RESISTOR,CERMET,JUMPER,0,+0.05

MAX,0.063W,0603,TAPE

RESISTOR, SMR,RES,CERM,10, +-1%,0.1W,100PPM,0805

THERMISTOR,POSITIVE,1.1K,+20%,COATED,RADIAL,TAPE

THERMISTOR, SMR,THERMISTOR,CHIP,NEG,50K,+-5%

VARISTOR, R05R,VARISTOR,910, +-10%,1.0MA

IC,ASIC,LTC984-1,+-2.5V,DMM FUNCTIONS W/O AD OR RMS CONVERTERS,SSOP36,TAPE

IC,MICROCONTROLLER,MSP430F448,16 BIT,1.8-3.6V,3.3MHZ,FLASH,PQFP100,TRAY

IC,ADC,LTC2435-1,2.7/5.5V,20BIT,DIFF,SERIAL,DELTA SIGMA,SSOP16,TAPE

IC,OP AMP,OPA2347,2.3 - 5.5V,6MV OFFSET,350KHZ,DUAL,U-PWR,R/R,SO8,TAPE

CMOS 4069 SMR,IC,CMOS,HEX INVERTER,SOIC

IC,VOLTAGE REGULATOR, LINEAR, TPS71533,3.3V,50MA,LDO,LOW POWER,SOT323-5,TAPE

Part

Number

943530 18612 CRCW-1206-4753F-RT2 2

649720 18612 CRCW-0603-1001FRT1 1

930081 18612 CRCW-0805-12R1F-RT1 1

2094011 59124 RN731JLTD2492D50 1

2126890 18612

928697 18612 CRCW-0805-4992F-RT1 1

605060 18612 CRCW-0603-1023FRT1 1

686748 18612 CRCW-0805-1073F-RT1 1

2065578 18612 CRCW06039762F-RT1 1

821678 18612 CRCW-1206-4993F-RT2 1

641974 18612 CRCW-0805-32R4F-RT1 1

944285 18612 CRCW-0805-4993F-RT1 2

688572 18612 CRCW-0603-2801FRT1 1

604394 18612 CRCW-0603-000-RT1 1

928924 18612 CRCW-0805-10R0-RT1 1

1277360 58090 YS3961 1

807875 18612 NTHS1005N01(50K-5%) 1

876193 34371 V910LSX1399 3

2103969 64155 LTC984-1 (SL10327) 1

2155866 01295

2063400 64155 LTC2435-1CGN 1

1618826 01295 OPA2347UA/2K5 1

838375 07263 CD4069UBCM 1

1999667 01295 BQ71533DCKR 1

Cage

Manufacturer’s

Part Number

TNPW06032493DT2RT1

MSP430F448IPZ (TRAYS)

Qty

87 V/AN

Service Manual

Table 18. A1 Main PCA (cont.)

Reference

Designator

U10

U12

U14

VR1

XF1- XF2 FUSE CONTACT 659524 89536 659524 2 XF3 XF4 FUSE CONTACT 707190 89536 707190 2

IC,RMS CONVERTER,AD737J-5,+-2.5V,LOW POWER,LOW SUPPLY VOLTAGE,SO8,TAPE

IC,VOLTAGE REFERENCE,LT1790,2.5V,0.1%,25PPM/C,60 UA,SOT-23-6,TAPE

IC,VOLTAGE REGULATOR, LINEAR, TPS77050,5V,50MA,LDO,LOW POWER,SOT23-5,TAPE

IC,ANALOG SWITCH,74HCT4053,5V,140 OHMS,TRIPPLE,SPDT,TSSOP16,TAPE

IC,LOGIC,7S08,2.0V-6.0V,SINGLE AND GATE,SC70-5,TAPE

ZENER,UNCOMP,MMSZ5237B,8.2V,5%, 20MA,500MW,SOD-123,TAPE

CRYSTAL,32.768KHZ,30/105PPM,7PF,CLIP CAN,SMD,TAPE

OEIGHTY-4R01T-N,R-NET, MF, POLY, SIP, OEIGHTY HI V DIVIDER

76-4R01T-K,R-NET, CERM, SIP, HI V PROTECT

Description

Part

Number

2089072 24355 AD737JR-5 1

1622188 64155 LT1790ACS6-2.5 1

1642135 01295 TPS77050DBVR 1

2064876 01295 CD74HCT4053PWR 1

2075176 07263 NC7S08P5X 1

1597952 89536 1597952 1

1627036 89536 1627036 1

2057204 89536 2057204 1

103454 89536 103454 1

Cage

Manufacturer’s

Part Number

Schematic Diagrams

Reference designator drawings and schematic diagrams are provided on the following pages.

Qty

Digital Multimeter

8X-5-4001

Schematic Diagrams

Figure 8. A1 LED PCA

87V/AN

COM

OUT CAV

PDN

VIN

VSP

VSM

V-

V+

V-

V+

VCC

VEEGND

9.997M

1.106M

110.01K

10.4K

440.4

AMP

V+

FE_O

FIL_C

FAMP_M

OUTPUT

CURRENT SOURCE

ISRC

CPC_S2

RJT_I

CPC_H

CURRENT

CONTROL

OUTPUT

LATCH

COMPARATOR

COMP

CONTROL

AMP

FILTER

GUARD

GRD

CONV_IN

FIL_IN

AGND

COMP_O

GRD

DIV_A

SCK SDI

ACAMP_O

V-

SENSE_HI

GRD

CNTL

CS*

POR*

IR2

IR1

CPC_S1

ZERO_IN

FAMP_O

DC AMP

3635

COMPUTER

INTERFACE

FREQ

ACAMP_M

SATION

AC COMPEN-

LEVEL

ADJUST

COMPARATOR

AC AMP

V-

GRD

4 3

DT, mA

TP6 S1-2 TP7 S1-6 TP8 S1-7 TP9 S1-8

REF DES NAME

TP3 S1-10 TP4 S1-3

TP36 PB3/BTXD

TP2 S1-14

TP1 S1-9

REF DES NAME

TEST POINTS

TP32,33 RST*

MODEL

TP17 +2.5

TP35 BRXD

mVDC (Temp)

(MODEL 87 ONLY)

RMS/AVG CONVERTER

(MODEL 83 ONLY)

TP23 RXD

PEAK DETECT

MUX

(MODEL 87 ONLY)

TP11 S1-4

TP29,30 TMS

TP28 -2.5

BOOTLOAD

TP24 TXD

TP5 S1-1

TP18 LCD_R23

TP16 POWER

TP15 BTP

TP12 GND

COMMON

TP13 Vbe

AMPS

TP20 SWPOS

mVDC (Temp) Ohms (Cap, Cont)

V/OHMS

TP21 VRSOB

UPPER TOP SHIELD CONTACT

TOP/BOTTOM SHIELD CONTACT

800 HZ FILTER (MODEL 87 ONLY)

TP14 BACKLIGHT

TP10 S1-5

MODEL 87 ONLY

TP34,38 +0.8

(MODEL 83 ONLY)

TP31 TCK

Ohms (Cap, Cont)

VDC, mVDC (Temp)

TP37 MODEL

JTAG TP25 TDO TP26,27 TDI

LOCATE NEAR

V TERMINAL

SERIAL COMM

MA/UA

TP22 LOWBATT

TP19 LCD_R13

Ohms (Cap, Cont)

uAmps

mAmps

.010 R6

TP4

MUXSW2

R30

NOLOAD

100P

NOLOAD

C47

0.001U

220 OHM

TP7

1000V

AC*

LPSW

LOWPASS

0.5%

10MM

2.5MM

910V

1.5MM

0.001U

C33

+2.5

R94

499K

R52

249K

100P

C56

100K

8MM

65 MIL

440MA

AC1

8MM

10.0M

-2.5

0.001U

C32

0.001U

C34

CR2

RV2

2.5MM

C43

226K

R29

R87

102K

CR1

COMMON

MMBT3904

0.1U

100K

0.0027U

0.01U

3.01K

2.80K

GRD

ASCK

+2.5

-2.5

DIN ACS* APOR*

2.5MM 2.5MM

1.00M

22U

8.2V

97.6K

1.00M

BAV199

CPH

220 OHM

-2.5

0.01U

MAJACK

261_MIL_WIDTH

BAV199

60_OHM

10.0M

499K

COMMON

8MM

MECCA

0.0068U

0.0

24.9K

ICNTL

+2.5

OPA2347

+2.5

1.00 1%

COMMON

226K

390P

0.1U

BAV199

1.10K

910V

11A

8MM

261 MIL

0.01U

1.00M

0.022U

AJACK

1.00M

0.022U

MMBT3904

107K

20%

BAV199

CPH

1000V

0.01U

60_OHM

100P

-2.5

910V

NOLOAD

10.0

-2.5

NOLOAD NOLOAD

60_OHM

+0.8

6.5MM

0.022U

NOLOAD

ADIN

100K

RT1

C10

R17

R18

R12

RV3 RV1

R51

132

R28

R35 R34

R10

C26

C31

R11

R48

AC2

R85

R86 R88

C36

C37

C38

R36

R37

R32

TP6

TP5

TP10TP11

TP8

TP9

TP13

TP12

R104

CR5

CR6

CR9

R100

VR1

CR10

R103

C39

R105

R111

856

-2.5

313334 30 21

11 12 1613 17

27 26 25

-2.5

BTP

0.0

U12

74HCT4053

-2.5

226K

MMBT3906

-2.5

OPA2347

0.0

R33

1.00M

33U

AD737J-2.5

0.001U

C35

+2.5

BAV199

CR8

499K

R101

110

-2.5

FASTADIN

ODCMP

R112

R113

1.5P

180P

C52

C58

NOLOAD

200K

MMSZ5237B

180P

49.9K

C46

8X-5-1001

(1 of 2)

Service Manual

Figure 8. A1 LED PCA (cont)

Digital Multimeter

P5.5/R13

P5.6/R23

P5.7/R33

R03

VEREF

VeREF-

VREF-/

VREF

XOUT/TCLK

P4.2/STE1/S39

DVCC2

XT2IN

RST*/NMI

DVCC

URXD1/P4.1

P4.3/SIMO1/S38

UTXD1/P4.0

AVCC

XT2OUT

P1.2/TA1

P1.3/TBOUTH/SVSOUT

P1.4/TBCLK/SMCLK

TCK

TDI

TMS

XIN

S10

S9 S8 S7 S6 S5 S4 S3 S2

S11

S17 S16 S15 S14 S13 S12

S18

S19

S20

S21

S23 S22

S33 S32

P3.0/STE0

P3.1/SIMO0

P3.3/UCLK0

P3.4/TB3

P3.5/TB4

P3.6/TB5

P3.7/TB6

P2.0/TA2

P2.1/TB0

P2.2/TB1

P2.3/TB2

P2.4/UTXD0

P2.5/URXD0

P2.6/CAOUT

P2.7/ADC12CLK

P1.0/TA0

P1.1/TA0/MCLK

P1.5/TACLK/ACLK

P1.6/CA0

P1.7/CA1

P6.0/A0

P6.1/A1

P6.2/A2

P6.3/A3

P6.4/A4

P6.5/A5

P6.6/A6

TDO/TDI

P4.7/S34

P4.6/S35

P4.5/UCLK/S36

P4.4/SOMI1/S37

S24

S25

S26

S27

S28

S29

S30

S31

P6.7/A7/SUSIN

P5.0/S1 P5.1/S0

COM1/P5.2

COM3/P5.4

COM2/P5.3

COM0

AVSS

DVSS1

DVSS2

P3.2/SOMI0

VIN

GND

VIN

REF

VCC

SCK

SDO

B32 B30 B25

B10

--X34 ___

B27

B22

B18B17 BT2 B15 B8

H4 5D

---

B11

B12

AUTO

B20

S35 S34 S33 S32 S31

S29

S30

S28

H2 H3 H4

S10 S9 S8 S7

S11

S13 S12

S15 S14

S16

S19 S18 S17

S20

S21

S25 S24 S23 S22

S26

S27

S4 S3 S2 S1

X19

X18X21

DEG_F

X13

X12

DEG_C

---

--X10 X20 MV

MIN

BT0 X32 X1

BT1

BT3

X22

BT4 B31 B24

---

MAX

X36

B16

B14

X37

B23

X23

X17

X7 X5

--X14 X15

AVG ---

2E 2C 3E 3C 4E 4C

---

1B,C

B19 X28 B13

B6 B3 X30 X33 X35

X29

B21

X26

X24

X11

B29 B26

B28

MAN

X25

X16

LOCATE C18, C19 NEAR PIN 100, TRACE TO 98

BACKLIGHT

PUSHBUTTON SWITCHES

BKLT

TP36 PB3/BTXD

TP35 BRXD

TP32,33 RST* TP34,38 +0.8

RSOB POSITION

IR COMMUNICATION

4.5 DIGIT LCD

TEST POINTS

REF DES NAME

TP12 GND

TP37 MODEL

BEEP

CAL

TP25 TDO

TP14 BACKLIGHT

BOOTLOAD

DEVELOPMENT ONLY

TP24 TXD TP5 S1-1 TP6 S1-6

TP18 LCD_R23

TP20 SWPOS

Ohms

CONVERTER

TP2 S1-14

TP10 S1-5

TP9 S1-8

TP4 S1-3

TP1 S1-9

TP7 S1-7 TP8 S1-8

OFF

COMPARE TO 1.2 V

REL

BEEPER

Diode Test

uAmps

mVDC

mA/Amps

TP21 VRSOB

TP17 +2.5

TP15 BTP TP16 POWER

RANGEMINMXSHIFT

A/D

HOLD

VAC VDC

MOMENTARY ON

C21,22 NEAR U3

TP19 LCD_R13

TP11 S1-4

TP3 S1-10

MODEL

SERIAL COMM

FLASH / BOOT

LCD COMPENSATION

TP13 Vbe

LOCATE C25, C29 NEAR PIN 1 AND 60, TRACE TO 99

MICROPROCESSOR

LOCATE C17, C27 NEAR PIN 10, TRACE TO 98

TP23 RXD

JTAG

TP22 LOWBATT

MODEL SELECTION

TP31 TCK

TP29,30 TMS

TP28 -2.5

TP26,27 TDI

REF DES NAME

POWER SUPPLY

LCD_R23

-2.5

NSCW100

DS3

TPS71533

3.3V

GND

OUT

R16

C28

BTP

C57

R110R109

TP38

R108

TP37

11 10

9 8 7 6

39 38 37 36 35 34

33 32 31 30 29 28 27 26 25 24

23 22 19 18 17 16 15 14 13 12

3 2

U11

C51C50

2823

2625

2423

149

109

C17

R98

R97

R99

Q17

R96

1615109871

TP19

TP22

TP18

TP21

TP20

TP14

TP17

TP16

TP15

TP3

TP2

TP1

Q12

TP24

TP23

TP33

TP30

TP27

TP36

TP35

TP34

TP32

TP31

TP29

TP28

TP26

TP25

U14

R84

R62

R73 R74

C18

11 10

21 20 19 18 17 16

51 50 49 48 47 46 45 44 43 42

41 40 39

37 36 35 34 33 32

31 30 29 28 27 26 25 24 23 22

13 12

59 58 57 56

6 5 4 3

2 97 96 95

62 63

65 66 67 68 69 70 71

72 73 74 75 76 77 78 79

80 81 82 83 84 85 86 87

5554535298

100

C29

R68

C27

R80

Q13

Q14

R47R44

C11

R53

R54

R55

R58

R59

R60

R61

C20

R22

R50

R46

R43R40

S10

R64

C24

R63

R65

R66

DS1

DS2

Q11Q10

R41

RT2

R27

R20

R25

R26

U10

C21 C22

R15

R31

S11

C16

C13

C12

C15

C14

R19

10 11

LS1

CR3

R14

C25

R21

C19

10U

NOLOAD

LCD40P

GF1B

1.00M

BTM

+0.8

VIN

IRLML6302

TCK

TDO

+0.8

RST*

TMS

TDI

-2.5

PB6

PB1

7S08

SEG25

0.1U

SEG16 SEG15

SEG10

SEG23

1.00K

MAJACK

4.7U

RXD

MMBT5089

LPSW

LOWBATT

SWPOS

AJACK

FASTADIN

MODEL

10V

-2.5

0.1U

10U

0.1U

GND

OUT

VOUT

1.00M

40.2K

BPR

LTC2435-1

1.00M

100K

12.1

MMBT5089

ADIN

100K100K

100K

226K

0.1U

GNDGND

845K

-2.5

10V

0.1U

100K

SWPWR

PB4 PB6

+0.8

-2.5

200K

BKLT

32.4

5.62K

HIBEAM

0.1U

1.00M

-2.5

SWPOS

100K

MMBT5089

CD4069

BTP

100K

-2.5 BTM

100K

50.0K 5%

100K

21.0K

100K

4.32K

LCD_R33

LCD_R23

LCD_R13

LCD_R03

-2.5

0.1U

49.9K

+2.5

-2.5

BTP

DOUT

ADCS*

ADSCK

MMBT3906

4.7K

100

SFH426

10.0K

MMBT5089

SFH325FA

MMBT5089

0.0082U

+0.8

TXD

-2.5

RXEN

COM2

COM3 COM1

-2.5

LCD_R13 LCD_R03

ACS*

SEG29

SEG30 SEG28

SEG27 SEG26

SEG24 SEG22

SEG21 SEG20 SEG19

SEG17

SEG18 SEG16

SEG15 SEG14

SEG12

SEG13 SEG11

SEG10 SEG9

SEG7

SEG8 SEG6

SEG5 SEG4 SEG3

TDI

TMS TDO

PB2

RST*

ASCK

10U

10V

SEG31

SEG32

SEG33

-2.5

DCMP

10.0K

+0.8

NOLOAD

SEG4 SEG3 SEG2 SEG1 SEG0

SEG27

SEG24

SEG25

SEG26

SEG23 SEG22

SEG19

SEG20

SEG21

SEG18 SEG17

SEG14

SEG11

SEG9

SEG7

SEG8

SEG6 SEG5

SEG28

SEG30 SEG29

COM1

SEG31

SEG13 SEG12

SEG2 SEG1 SEG0

MODEL

475K

CD4069

0.0

ADSCK

LCD_R33

COM0

SEG33 SEG32

ADCS*

COM0

APOR* DIN

0.1U

-2.5

475K

MMBT5089

RXEN

+0.8

COM3

COM2

NOLOAD

+0.8

-2.5

32.768KHZ

TPS77050

5.0V NC

100K

NOLOAD

100P

NOLOAD

10.0

NOLOAD

470P

CD4069

PB5

V5*

DOUT

ICNTL

TCK

SMCLK

MSP430F448

5.62K

1.00K

BPR

AC*

BKLT

TXD

RXD

PB5

PB4

BRXD

PB3/BTXD

MUXSW2

HIBEAM

PB3/BTXD

BRXD

SWPWR

LOWPASS

+0.8

PB2

PB1 PB3/BTXD

ODCMP

1.00K

4.7U

+2.5

100P

10.0

-2.5

16V

10U

47U

-2.5

LOWBATT

V5*

0.01U

LT1790

2.5V

MMBT3904

8X-5-1001

(2 of 2)

Schematic Diagrams

Figure 8. A1 LED PCA (cont)

87V/AN

Service Manual

Fluke 87 V-an User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Table of Contents

List of Tables

List of Figures

Introduction

Contacting Fluke

Unpacking the Meter

Inspection

Inspection Interval

Preparations for Use

Precautions and Safety Information

Electrical Symbols

Specifications

General Specifications

Detailed Specifications

Theory of Operation

Functional Block Diagram

Power Supply and Voltage Reference

Function Selection and Overload Protection

Analog Signal Conditioning

mVDC

Temperature

Continuity in all Ohms and the Siemens Ranges

Capacitance

Diode Test

Active Filter

800 Hz Low Pass Filter

RMS to DC Converter

Analog to Digital Converter

Secondary Analog Circuits

Keypad

Microprocessor & Support Circuits

Backlight

Beeper

Troubleshooting

Restoration Actions

Basic Maintenance

Cleaning the Meter

Opening the Meter Case

Accessing the PCA and Replacing the LCD

Reassembling the Meter Case

Replacing the Battery

Testing Fuses and Current Circuitry

Replacing the Fuses

Required Equipment

Performance Tests

Basic Operability Tests

Testing the Fuses

Testing the Display

Testing the Pushbuttons

Testing Meter Accuracy

Calibration Adjustment

Calibration Adjustment Counter

Calibration Adjustment Password

Changing the Password

Restoring the Default Password

Meter Buttons Used in the Calibration Steps

Calibration Adjustment Procedure

Service and Parts

Schematic Diagrams