Fluke 10 User manual

®
10,11,12
Multimeters
Service
PN 900824
March 1992 Rev.1, 7/93
© 1992-1993 Fluke Corporation, All rights reserved. Printed in USA
All product names are trademarks of their respective companies.

WARRANTY
Fluke warrants to the original product purchaser that each product it manufactures will
be free from defects in material and workmanship under normal use and service. The
warranty period is controlled by the warranty document furnished with each product and
begins on the date of shipment. Fluke’s warranty does not apply to fuses, batteries,
CRTs or any product which, in Fluke’s opinion, has been misused, altered, neglected, or
damaged by accident or abnormal conditions of operation or handling.
To obtain warranty service in the USA, call 1-888-99-FLUKE (1-888-993-5853). Outside
the USA, contact your nearest Fluke sales or service representative. Fluke assumes no
risk for damage in transit. Fluke will, at its option, repair or replace the defective product
free of charge or refund the purchase price. However, if Fluke determines that the failure
was caused by misuse, alteration, accident, or abnormal condition of operation or
handling, you will be billed for the repair and the repaired product will be returned to you
transportation prepaid.
THIS WARRANTY IS EXCLUSIVE 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
OR USE. FLUKE WILL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL,
OR CONSEQUENTIAL DAMAGES OR LOSS OF DATA, WHETHER IN CONTRACT,
TORT, OR OTHERWISE.
Some states do not allow the exclusion or limitation of incidental or consequential
damages, or implied warranty periods, so the above limitations may not apply to you.
Other rights may vary from state to state.
Fluke Corporation Fluke Europe B.V
P.O. Box 9090 P.O. Box 1186
Everett, WA 98206-9090 5602 BD Eindhoven
U.S.A. The Netherlands

MULTIMETER SAFETY
The Fluke 10, 11, 12 Multimeters have been designed and tested according to IEC
Publication 348, Safety Requirements for Electronic Measuring Apparatus. This manual
contains information and warnings which must be followed to ensure safe operation and
retain the meter in safe condition. Use of this equipment in a manner not specified herein
may impair the protection provided by the equipment.
These mutimeters comply with part 15 of the FCC Rules. Operation is subject to the
following two conditions: (1) these multimeters may not cause harmful interference, and
(2) these multimeters must accept any interference received, including interference that
may cause undesired operation.
Some common international electrical symbols used in this manual are shown below.
BAC - ALTERNATING
CURRENT YDANGEROUS VOLTAGE
FDC - DIRECT
CURRENT JEARTH GROUND
DEITHER AC OR DC
CURRENT WSEE EXPLANATION
IN MANUAL
IFUSE TDOUBLE INSULATION
FOR PROTECTION
AGAINST ELECTRIC
SHOCK
Before using the meter, read the following safety information carefully. In this manual,
"WARNING," is reserved for conditions and actions that pose hazard(s) to the user;
"CAUTION," is reserved for conditions and actions that may damage your meter.
•Avoid working alone
•Follow all safety procedures for equipment being tested.
•Inspect the test leads for damaged insulation or exposed metal. Check test lead
continuity. Damaged leads should be replaced.
•Be sure the meter is in good operating condition.
•Select the proper function for your measurement.
•To avoid electrical shock, use caution when working above 60V dc or 30V ac RMS.
•Disconnect the live test lead before disconnecting the common test lead.
•Disconnect the power and discharge high-voltage capacitors before testing in Ωand
LR.
•When making a current measurement, turn the circuit power off before connecting
the meter in the circuit.
•Check meter fuses before measuring transformer secondary or motor winding
current. An open fuse may allow high voltage build-up, which is potentially
hazardous.
•Use clamp-on probes when measuring circuits exceeding 10 amps.
•When servicing the meter, use only the replacement parts specified.
•Do not allow meter to be used if it is damaged or if its safety is impaired.

i
Table of Contents
Chapter Title Page
1 Introduction and Specifications ........................................................ 1-1
1-1. Introduction........................................................................................... 1-1
1-2. Specifications........................................................................................ 1-1
2 Theory of Operation ........................................................................... 2-1
2-1. Introduction........................................................................................... 2-3
2-2. Theory of Operation.............................................................................. 2-3
2-3. Analog Measurement IC (U1).......................................................... 2-3
2-4. Microcomputer IC (U2).................................................................... 2-3
2-5. VCHEK Input Resistance................................................................. 2-3
3 Maintenance........................................................................................ 3-1
3-1. Introduction........................................................................................... 3-3
3-2. Disassembly and Reassembly............................................................... 3-3
3-3. Cleaning................................................................................................ 3-7
3-4. Performance Tests................................................................................. 3-7
3-5. Calibration ............................................................................................ 3-8
4 Replaceable Parts and Schematics................................................... 4-1
4-1. Introduction........................................................................................... 4-3
4-2. How To Obtain Parts ............................................................................ 4-3
4-3. Schematics............................................................................................ 4-3
4-4. Warranty and Service Centers .............................................................. 4-4

iii
List of Tables
Table Title Page
1-1. Specifications......................................................................................................... 1-2
2-1. Electrical Components on Main PCA.................................................................... 2-4
2-2. U1 Pinout Table ..................................................................................................... 2-5
3-1. Required Equipment............................................................................................... 3-7
3-2. Performance Tests for Fluke 10 ............................................................................. 3-9
3-3. Performance Tests for Fluke 11 and 12.................................................................. 3-10
4-1. Final Assembly....................................................................................................... 4-5
4-2. A1 Main PCA......................................................................................................... 4-7

v
List of Figures
Figure Title Page
2-1. Typical VCHEK Input Resistance with DC Volts Function Selected ................... 2-7
3-1. Disassembled Unit.................................................................................................. 3-4
3-2. Removing and Reinserting the Printed Circuit Assembly...................................... 3-5
3-3. Calibration Adjustment.......................................................................................... 3-10
4-1. Final Assembly Drawing........................................................................................ 4-6
4-2. A1 Main PCA Components.................................................................................... 4-9
4-3. Fluke 10 Schematic................................................................................................ 4-10
4-4. Fluke 11 Schematic................................................................................................ 4-12
4-5. Fluke 12 Schematic................................................................................................ 4-14

1-1
Chapter 1
Introduction and Specifications
Title Page
1-1. Introduction........................................................................................... 1-3
1-2. Specifications........................................................................................ 1-3

Introduction and Specifications
Introduction 1
1-3
1-1. Introduction
WARNING
SERVICE PROCEDURES DESCRIBED HEREIN SHOULD BE
PERFORMED BY QUALIFIED PERSONNEL ONLY. TO AVOID
ELECTRIC SHOCK, PERFORM ONLY THOSE SERVICE
PROCEDURES IN THIS INSTRUCTION SHEET.
The 10 Series Service Manual provides the information necessary to service the Fluke
Model 10, Model 11, and Model 12 Multimeters. The following information is provided
in this publication:
•Specifications (Section 1)
•Basic theory of operation (Section 2)
•Disassembly and reassembly (Section 3)
•Performance tests (Section 3)
•Calibration (Section 3)
•Illustrated parts lists and schematic diagram (Section 4)
•Refer to the Users Manual for operating instructions.
1-2. Specifications
Specifications are in Table 1-1. Accuracy is specified for a period of one year after
calibration, at 18°C to 28°C (64°F to 82°F) with relative humidity to 90%. AC
conversions are ac-coupled, average responding, and calibrated to the rms value of a sine
wave input.
Accuracy specifications are given as:
±([% of reading] + number of least significant digits])

10, 11, 12 Multimeters
Service Manual
1-4
Table 1-1. Specifications
Maximum Voltage
Between any Terminal
and Earth Ground
600V ms
Display 3 3/4-digits, 4000 counts, updates 4/sec
Operating Temperature -10°C to 50°C
Storage Temperature -30°C to 60°C indefinitly (to -40°C for 100 hrs)
Temperature Coefficient 0.1 x (specified accuracy)/°C (<18°C or >28°C)
Relative Humidity 0% to 90% (-10°C to 35°C) 0% to 70% (35°C to 50°C)
Battery Type 9V, NEDA 1604 or IEC 6F22
Battery Life 650 continious hours with alkaline 450 continious hours with carbon-zinc
Shock, Vibration 1 meter shock. Per MIL-T-28800D for a Class 3 Instrument
Size (HxWxL) 1.35 in x 2.75 in x 5.55 in (3.46 cm x 7.05 cm x 14.23 cm)
Weight 10 oz (286 g)
Safety Designed to Protection Class II requirement of UL1244, ANSI/ISA-S82,
CSA C22.2 No 231, and VDE 0411, and IEC 1010 overvoltage category
III.
EMI Regulations Complies with FCC Part 15, Class B, and VDE 0871B.
Accuracy (50 to 400 Hz)Function Range Resolution
Model 10 Models 11/12
Volts AC 4000 mV* 1 mV ±(2.9%+3) ±(1.9%+3)
4.000V 0.001V ±(2.9%+3) ±(1.9%+3)
40.00V 0.01V ±(2.9%+3) ±(1.9%+3)
400.0V 0.1V ±(2.9%+3) ±(1.9%+3)
600V 1V ±(2.9%+3) ±(1.9%+3)
Volts DC 4000 mV 1 mV ±(1.5%+2) ±(0.9%+2)
4.000V 0.001V ±(1.5%+2) ±(0.9%+2)
40.00V 0.01V ±(1.5%+1) ±(0.9%+1)
400.0V 0.1V ±(1.5%+1) ±(0.9%+1)
600V 1V ±(1.5%+1) ±(0.9%+1)
Resistance 400.0Ω0.1Ω±(1.5%+2) ±(0.9%+2)
4.000 kΩ0.001 kΩ±(1.5%+1) ±(0.9%+1)
40.00 kΩ0.01 kΩ±(1.5%+1) ±(0.9%+1)
400.0 kΩ0.1 kΩ±(1.5%+1) ±(0.9%+1)
4.000 MΩ0.001 MΩ±(1.5%+1) ±(0.9%+1)
40.00 MΩ0.01 MΩ±(1.9%+3) ±(1.5%+3)
Capacitance 1.000 µF 0.001 µFNA ±(1.9%+2)
10.00 µF 0.01 µFNA ±(1.9%+2)
100.0 µF0.1µFNA ±(1.9%+2)
1000 µF1µFNA±(1.9%+2)
10000 µF 10 µF NA ±(10%+90) Typical
Continuity/Diode
Test 2.000V 0.001V ±(1.5%+2) ±(0.9%+2)
* The 4000 mV range can only be entered in the manual range mode. Use the 4000 mV range with
accessories.
** The beeper is guaranteed to come on at <25Ωand turn off at >250Ω. The meter detects opens or shorts
of 250 µs or longer.

Introduction and Specifications
Specifications 1
1-5
Table 1-1. Specifications (cont)
Function Overload
Protection* Input Impedance (Nominal) Common Mode Rejection Ratio
(1 kΩUnbalance)
Normal Mode
Rejection
Volts DC 600V rms >10 MΩ<100 pF
kCHEK & LoZ= >2 kΩ
<200 pF**
>100 dB at dc, 50 Hz,
or 60 Hz >50 dB at 50 Hz or 60 Hz
Volts AC 600V rms >5 MΩ<100 pF kCHEK
& LoZ= >2 kΩ<200
pF** (ac-coupled)
>60 db, dc to 60 Hz
Resistance Open Circuit
Test Voltage Full Scale Voltage To 4.0 MΩ40 MΩShort Circuit Current
600V rms <1.5V dc dc <450 mV 1.5V dc <500 uA
Diode 600V rms 2, 4-3. 0V dc 2,400V dc 0.95 mA typical
* 3 x 106 V Hz Maximum
** Models 11 and 12 only
MIN MAX Recording with Elapsed Time (Model 12 Only)
Specified accuracy of the measurement function ± 12 digits for changes >200 ms in duration (±40 digits in
ac). Typical 100 ms response to 80%.
Elapsed Time Resolution Accuracy
0 to 100 hours 1 minute 0.3% typical
(99:59)
Continuity Capture (Model 12 Only)
Detects opens or shorts of 250 µs or longer.

2-1
Chapter 2
Theory of Operation
Title Page
2-1. Introduction........................................................................................... 2-3
2-2. Theory of Operation ............................................................................. 2-3
2-3. Analog Measurement IC (U1).......................................................... 2-3
2-4. Microcomputer IC (U2).................................................................... 2-3
2-5. VCHEK Input Resistance................................................................. 2-3

10, 11, 12 Multimeters
Service Manual
2-2

Theory of Operation
Introduction 2
2-3
2-1. Introduction
Section 2 provides a basic theory of operation for the Series 10 Multimeters. Electrical
components on the printed circuit assembly (A1 Main PCA) are listed in Table 2-1.
Refer to Figure 4-2 for the location of these components and Figures 4-3 through 4-5 for
the schematic diagrams.
2-2. Theory of Operation
The analog/digital IC (U1) implements the electrical measurement functions. See Table
2-2 for pin names and descriptions. The microcomputer (U2) controls U1, the LCD (U3),
and the user interface. Discrete components support U1 and U2, provide reference
standards for measurements, and provide input overload protection.
2-3. Analog Measurement IC (U1)
U1 implements the following analog functions: a/d converter, ac to dc converter,
VCHEK circuitry (Models 11 and 12 only), active filter, passive filter, power supply,
range configuration circuitry, signal routing circuitry, beeper driver, digital control
circuitry, and digital U2 interface circuitry.
The a/d converter is a patented dual-rate, dual-slope converter. The dual-rate conversion
allows for MIN MAX (Model 12 only) and fast autoranging functions. The ac to dc
converter is full-wave rectified and average-responding. The active and passive filters
are two-pole and one-pole low-pass filters (respectively) that are used for signal filtering
prior to a/d conversion. The internal power supply generates a ground voltage nominally
+3V relative to VSS. Range configuration circuitry connects the Z1 resistor network as
needed for different ranges. Routing circuitry connects the various signal conditioning
circuits as needed. The a/d converter and a counter are controlled by a state machine.
Finally, digital circuitry interfaces with U2 via a parallel address and bidirectional data
bus.
Voltage is measured using a ratio comparison of the unknown voltage to the reference
voltage (REFI pin). Resistance is calculated using a ratio comparison of the voltage
across the unknown resistor to the voltage across a precision reference resistor, with the
same current in both. Capacitance is measured by determining the amount of charge
added for a given dc voltage change.
2-4. Microcomputer IC (U2)
U2 writes range settings and a/d converter information to U1. U2 reads a/d converter
results and status information. This includes the low battery check, slide-switch position,
continuity check, and VCHEK data. The microcomputer performs math operations on
the raw data from U1 and configures it for the LCD. U2 also reads pushbutton inputs.
Finally, the 2.1 MHz clock signal at U2 is divided down to 131 kHz and sent to U1
(CLK pin) for the counter.
2-5. VCHEK Input Resistance
As shown in Figure 2-1, the input resistance for the VCHEK function is non-linear. The
data in the graph are for the volts dc function (any range) and are the steady state values
obtained after the PTC thermister (RT1) has stabilized. The data also apply for the volts
ac function.

10, 11, 12 Multimeters
Service Manual
2-4
Table 2-1. Electrical Components on Main PCA
Circuit and Function Component Designator(s)
Analog Measurement IC U1
Microcomputer IC U2
Input Divider and Ohms Reference Resistor Network Z1
Input Divider AC Coupling Capacitor C14
J2 Input Receptable Voltage Sense Resistor R17
J1 Input Receptable Voltage Sense Resistor R14
Reference Voltage for Volts Measurements VR1, R4, R5, R6, R26
A/D Converter Integrate Capacitor C2
A/D Converter Autozero Capacitor C1
A/D Converter Gain Resistors R1, R3, R15
Active Filter Components R7, R8, C5, C6
Passive Filter Components R9, C7
AC to DC Converter Gain Resistors R11, R12, R13
AC to DC Converter AC Coupling Capacitor C8
Bias Current Setting Resistor R2
DGND-VSS Voltage Setting Resistors R10, R24
Power Supply Bypass Capacitors C3, C15
Reverse Battery Protection CR1
System Clock Y1
VCHEK Input Current Limiters R16, R18, R29
VCHEK input Positive Temp. Coef. Thermistor RT1
VCHEK Input Voltage Clamp Circuit Q1, Q2, CR2, R28
VCHEK Input Fusible Resistor R19
Microcomputer Reset Circuit R23, R25, C10, C13, CR3
On/Off and VCHEK Select Slide Switch S1
Beeper LS1
Beeper Current Limiter R22
Slide Switch Protection E1
Switch Sense Bypass Capacitor C9
Input Divider Bypass Capacitor C16
Zero Ohm Jumpers R20, R21, R27