Test Equipment Depot 88 User manual

88
Automotive Meter
Service Manual
For IEC 61010 CAT II Meters Only
PN 666856
November 1998 Rev.1, 11/99
© 1998, 1999 Fluke Corporation. All rights reserved. Printed in U.S.A.
All product names are trademarks of their respective companies.
Test Equipment Depot
99 Washington Street
Melrose, MA 02176-6024

Test Equipment Depot
99 Washington Street
Melrose, MA 02176-6024
www.testequipmentdepot.com
800-517-8431
781-665-0780 FAX

LIMITED WARRANTY & LIMITATION OF LIABILITY
Fluke Corporation (Fluke) warrants this product to be free from defects in material and workmanship under normal use and service for the life
of the product. This warranty extends only to the original buyer or end-user customer of a Fluke authorized reseller, and does not apply to
fuses, batteries or to any product which, in Fluke’s opinion, has been misused, altered, neglected or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate on appropriate Fluke instruments 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.
Fluke’s warranty obligation is limited, at Fluke’s option, to refund of the purchase price, or free of charge repair or replacement of a defective
product which is returned to an authorized Fluke Service Center within the warranty period.
To obtain warranty service, contact your nearest Fluke Service Center or send the product, with a description of the difficulty, postage and
insurance prepaid (FCA Destination), to the nearest Fluke Service Center. Fluke assumes no risk for damage in transit. Following warranty
repair, the product will be returned to Buyer, transportation prepaid (FCA Destination). If Fluke determines that the failure was caused by
misuse, alteration, accident or abnormal condition of operation or handling, 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 (FCA Shipping Point).
Warranty service is available outside the United States only if product was purchased through a Fluke Authorized Sales Outlet in the country
of use or the applicable Fluke international price was paid. Product transported from the United States for which the applicable Fluke
international price was not paid must be returned to the U.S. to receive warranty service, at the shipment expense and risk of Buyer. 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.
THIS WARRANTY IS PURCHASER’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, WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT,
RELIANCE OR ANY OTHER 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 of competent jurisdiction, such holding will not affect the validity or enforceability of any other provision of
this warranty. Fluke Corporation Fluke Europe B.V.
P.O. Box 9090 P.O. Box 1186
Everett WA 5602 B.D. Eindhoven
98206-9090 The Netherlands

Safety-1
Safety Information
This meter complies with EN 61010-1:1993, ANSI/ISA S82.01-1994 and CAN/CSA
C22.2 No. 1010.1-92 Overvoltage Category II. Use the meter only as specified in the
Users Manual, otherwise the protection provided by the meter may be impaired.
A Warning identifies conditions and actions that pose hazards to the user; a Caution
identifies conditions and actions that might damage the meter. International electrical
symbols used on the meter are shown below.
WWarning
To avoid possible electric shock or personal injury:
•Do not use the meter if it is damaged. Before use, inspect the
case for cracks or missing plastic. Pay particular attention to the
insulation surrounding the connectors.
•Always turn off power to the circuit before cutting, unsoldering,
or breaking the circuit. Small amounts of current can be
dangerous.
•Inspect the test leads for damaged insulation or exposed metal.
Check test lead continuity. Replace damaged leads.
•To avoid damage or injury, never use the meter on unprotected
circuits that exceed 4800 volt-amps.
•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.
•Do not apply more than 300 V dc or ac rms (sine) between
terminals or between any terminal and earth ground.
•Before each use, verify the meter’s operation by measuring a
known voltage.
•When servicing the meter, use only specified replacement parts.
•Use caution when working above 30 V ac rms, 42 V ac peak, or 60
V dc. Such voltages pose a shock hazard.
•Keep your fingers behind the finger guards on the probe when
making measurements.
•Connect the common test lead before connecting the live test
lead. Disconnect the live test lead first.
•Remove test leads from the meter before opening the case.
•Use only a single 9 V battery, properly installed in the meter case,
to power the meter.
•Follow all equipment safety procedures.
•Before measuring current, check the meter’s fuses (see “How to
Test the Fuse”).

Safety-2
•Never touch the probe to a voltage source when the test leads are
plugged into the 10 A input jack.
•Always use clamp-on probes (dc current clamps) when
measuring current exceeding 10 A.
•DO NOT connect thermocouple to voltages exceeding 30 V.
•Always use a high voltage probe to measure voltage if peak
voltage might exceed 300 V.
•To avoid false readings, which could lead to possible electric
shock or personal injury, replace the meter’s battery as soon as
the low battery indicator (N) appears.
•To avoid fire hazard, only use a fuse identical in type, voltage
rating, and current rating to that specified on the fuse rating label
located on the case bottom.
•Do not operate the meter if it is disassembled. Always operate the
meter with the case top and bottom properly assembled.
Disassembly procedures and warnings are in the 78 Automotive
Service Manual. Service procedures are for qualified personnel
only.
Caution
To avoid possible damage to the meter or to equipment under
test:
•Disconnect the power to the circuit under test and discharge all
high voltage capacitors before testing resistance, continuity or
diodes.
•Use the proper function and range for your measurement
applications.
•When measuring current, turn off circuit power before connecting
the meter in the circuit. Remember to place the meter in series
with the current.
Symbols
Symbol Meaning
Important information. See manual.
Ground
Fuse
Double insulation (Protection Class II)
Conforms to European Union directives

i
Table of Contents
Chapter Title Page
1 Introduction and Specifications........................................................ 1-1
1-1. Introduction.......................................................................................... 1-3
1-2. Organization of the Service Manual..................................................... 1-3
1-3. Conventions.......................................................................................... 1-4
1-4. Specifications....................................................................................... 1-4
2 Theory of Operation........................................................................... 2-1
2-1. Introduction.......................................................................................... 2-3
2-2. Functional Block Description............................................................... 2-3
2-3. Detailed Circuit Description ................................................................ 2-5
2-4. Input Overload Protection................................................................ 2-5
2-5. Rotary Switch................................................................................... 2-5
2-6. Input Signal Conditioning Circuits.................................................. 2-5
2-7. Volts............................................................................................. 2-6
2-8. Ohms............................................................................................ 2-6
2-9. Analog Section of Integrated Meter IC (U4)................................... 2-6
2-10. Microcomputer Control ................................................................... 2-8
2-11. Peripherals to U4.............................................................................. 2-9
2-12. AC Buffer .................................................................................... 2-10
2-13. AC Converter............................................................................... 2-10
2-14. Active Filter................................................................................. 2-10
2-15. A/D Converter ............................................................................. 2-10
2-16. Beeper.......................................................................................... 2-10
2-17. Reference Voltage ....................................................................... 2-10
2-18. Power Supply............................................................................... 2-10
2-19. Display............................................................................................. 2-11
2-20. Rotary Knob Switch and Potentiometer .......................................... 2-11
3 Maintenance....................................................................................... 3-1
3-1. Introduction.......................................................................................... 3-3
3-2. Required Tools and Equipment............................................................ 3-3
3-3. Operator Maintenance.......................................................................... 3-4
3-4. Disassembing the Case..................................................................... 3-5
3-5. Removing and Reinstalling the Circuit Assembly........................... 3-5

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Service Manual
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3-6. Reassembling the Case..................................................................... 3-6
3-7. Replacing the Battery....................................................................... 3-7
3-8. Testing Fuses ................................................................................... 3-7
3-9. Replacing Fuses ............................................................................... 3-7
3-10. Cleaning........................................................................................... 3-8
3-11. Input Terminals............................................................................ 3-8
3-12. Function Encoding Potentiometer ............................................... 3-8
3-13. Performance Test.................................................................................. 3-9
3-14. Testing the Display .......................................................................... 3-9
3-15. Testing Function Selection (Rotary Switch).................................... 3-10
3-16. Testing the AC Voltage Function.................................................... 3-10
3-17. Testing the Frequency Counter Function......................................... 3-11
3-18. Testing Frequency Sensitivity and Trigger Level............................ 3-12
3-19. Testing the DC Voltage Function.................................................... 3-12
3-20. Testing the DC mV Function........................................................... 3-13
3-21. Testing the Ohms Function.............................................................. 3-13
3-22. Testing the Diode Test Function...................................................... 3-13
3-23. Testing the mA Functions................................................................ 3-13
3-24. Testing the Amp Functions.............................................................. 3-14
3-25. Testing the Inductive Pickup............................................................ 3-14
3-26. Calibration............................................................................................ 3-18
3-27. Troubleshooting the Power Supply...................................................... 3-19
3-28. Common (Shunt) Regulator Troubleshooting.................................. 3-21
3-29. VDD (Series) Regulator Troubleshooting....................................... 3-23
3-30. Troubleshooting a Function Selection Malfunction............................. 3-23
3-31. Meter Does Not Turn Off (Problem 1)............................................ 3-24
3-32. Meter Enters Wrong Function (Problem 2) ..................................... 3-24
4 List of Replaceable Parts .................................................................. 4-1
4-1. Introduction.......................................................................................... 4-3
4-2. How to Obtain Parts............................................................................. 4-3
4-3. Manual Status Information................................................................... 4-3
4-4. Newer Instruments................................................................................ 4-4
4-5. Service Centers..................................................................................... 4-4
4-6. Parts Lists............................................................................................. 4-4
5 Schematic Diagrams.......................................................................... 5-1

iii
List of Tables
Table Title Page
1-1. Summary of Accuracy Specifications.................................................................... 1-5
2-1. Typical Voltage Levels and Tolerance.................................................................. 2-11
3-1. Required Equipment.............................................................................................. 3-3
3-2. Function Selection Test......................................................................................... 3-10
3-3. AC Voltage Test.................................................................................................... 3-11
3-4. Frequency Test....................................................................................................... 3-11
3-5. Frequency Counter Sensitivity and Trigger Level Tests....................................... 3-12
3-6. DC Voltage Test.................................................................................................... 3-12
3-7. Ohms Test.............................................................................................................. 3-13
3-8. Milliamp Tests....................................................................................................... 3-14
3-9. Amp Tests.............................................................................................................. 3-14
3-10. Functional Description of Power Supply Components ......................................... 3-20
3-11. Voltage Levels....................................................................................................... 3-20
4-1. Fluke 88 Final Assembly....................................................................................... 4-5
4-2. A1 Main PCA........................................................................................................ 4-7

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Service Manual
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v
List of Figures
Figure Title Page
2-1. Overall Functional Block Diagram........................................................................ 2-4
2-2. A/D Conversion..................................................................................................... 2-8
2-3. Function-Encoding Switch .................................................................................... 2-12
3-1. Battery and Fuse Replacement .............................................................................. 3-4
3-2. Assembly Details................................................................................................... 3-6
3-3. Display Test........................................................................................................... 3-9
3-4. Setup for Inductive Pickup Test ............................................................................ 3-16
3-5. Waveform for Inductive Pickup Test..................................................................... 3-17
3-6. Calibration Adjustment Points............................................................................... 3-19
3-7. Simplified Power Supply Schematic ..................................................................... 3-22
4-1. Fluke 88 Final Assembly....................................................................................... 4-6
4-2. A1 Main PCA........................................................................................................ 4-9
5-1. A1 Main PCA........................................................................................................ 5-3

88
Service Manual
vi
88
AUTOMOTIVE METER
MIN MAX RANGE HOLD
H
%DUTY ALERT
ZERO
RPM
AVG
H
M k
4000
mV
20 2 4 6 3108 2 4 6 8 420
TRIG
_
+
_ +
AUTO RANGE RECORD MAX MIN AVG
ACDC
m s %
m V A
+
T
Hz
RPM
12
POWER-UP OPTIONS
PRESS 2 SEC. WHILE TURNING METER ON
LOW, OHMS/HIGH RESOLUTION
DISABLE AUTOMATIC POWER-OFF
AUTORANGE VDC, VAC
HI IMPENDANCE mV DC INPUT
TURN OFF BEEPER
TEST ROTARY SWITCH
HI ACCURACY, 1 SEC. RESPONSE
ZERO
MIN MAX
RANGE
HOLD
ALERT
RPM
WARNING
TO AVOID ELECTRICALSHOCK REMOVE
TEST LEADS BEFORE OPENING CASE
TO PREVENT DAMAGE OF INJURY
INSTALL QUICKACTING FUSES WITH
AMP/VOLT RATINGS SHOWN.
POWER-UP OPTIONS
DISPLAY
PUSHBUTTONS
ROTARY SWITCH
ELECTRICAL SHOCK
AND FUSE WARNINGS
BATTERY TYPE
BACK
FUSE RATINGS
SKID
RESISTANT
FEET
INPUT TERMINALS
FRONT
9V NEDA 1604
F 44/100A 1000V
MIN INTERRUPT RATING 10 000A
F 11A 1000V
MIN INTERRUPT RATING 17 000A
FLUKE CORPORATION
MADE IN USA
PAT. RE. 34,428 DES. 314,715 DES. 312,534 4,217,543
4,556,867 4,532,470 5,073,757 4,940,204 4,951,834
PRODUCT
SERVICE
OFF
RPM
AmA COM RPM
V
400mA
FUSED
10A
FUSED
Hz ms-PULSE TRIGGER
SMOOTH
mV
V
V
mA
A
mA
A
+
300V
CATII
LR44340
aad01f.eps
Frontispiece