Fluke 79 III Use and care manual

®
PN 659349 December 1997 Rev.2, 3/00 ©1997, 1999, 2000 Fluke Corporation. All rights reserved. Printed in U.S.A. 1
79/26
Series III Multimeter
Calibration Information
Introduction
WWarning
To avoid electric shock, do not perform any servicing other than that contained
in the Users or Service manual unless you are qualified to do so. These service
instructions are for use by qualified personnel only.
This Calibration Information for the 79/26 Series III Multimeter (hereafter known as “the Meter”) provides
the information necessary to calibrate the meter and verify its performance. This information sheet provides
the following information:
•Product specifications
•Specifications
•Basic Maintenance
•Disassembly and reassembly
•Performance test procedures
•Calibration and calibration adjustment procedures
•Replacement parts
For complete operating instructions, refer to the 79/26 Series III Instruction Sheet.
Service
The Meter has a limited lifetime warranty. To contact Fluke, call one of the following telephone numbers:
USA: 1-888-99-FLUKE (1-888-993-5853)
Canada: 1-800-36-FLUKE (1-800-363-5853)
Europe: [phone]
Japan: [phone]
Singapore: [phone]
Anywhere in the world: [phone]
For additional information about Fluke, its products, and services, visit Fluke’s web site at:
www.fluke.com

79/26
Calibration Information
2
Safety Information
WWarning
To avoid electric shock and personal injury:
•Do not use the Meter if it is damaged. Before you use the Meter, inspect the
case and look for cracks or missing plastic. Pay particular attention to the
insulation surrounding the connectors.
•Inspect the test leads for damaged insulation or exposed metal. Check for
continuity in the test leads. Replace damaged test leads before you use the
Meter.
•Do not use the Meter if it operates abnormally. Protection may be impaired.
When in doubt, have the meter serviced.
•When you service the Meter, use ONLY replacement parts specified in the
manual.
•Do not operate the Meter around explosive gas, vapor, or dust.
•Never apply more than rated voltage between any input terminal and
ground.
•Be sure the test leads and rotary switch are in the correct position for the
desired measurement.
•Never measure resistance in a circuit when power is applied.
•Never touch the probe to a voltage source when the test leads are plugged
into the 10 A or 40 mA input terminal.
•Be careful when working with voltages above 60 V dc or 30 V ac rms. Such
voltages pose a shock hazard.
•Keep your fingers behind the finger guards on the test probes when making
measurements.
•Use only a single, 9V battery that is properly installed in the meter case to
power the Meter.
To avoid false readings which could lead to possible electric shock or personal
injury, replace the battery immediately after the battery symbol displays.

Series III Multimeter
Specifications
3
Specifications
Specifications are in Table 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 and true rms
responding.
Table 1. Specifications
Display: Digital: 4000 counts, updates 4/sec
Analog: 63 segments, updates 40/sec
Frequency: 9,999 counts
Capacitance: 9,999 counts
Response Time of
Digital Display: V ac <1.5 s (for upscale only) V dc <1 s
Ω<1 s to 40 kΩ, <2 s to 4 MΩ, <10 s to 40 MΩ
Operating Temperature: 0 °C to 55 °C
Storage temperature: -40 °C to 60 °C
Temperature Coefficient: 0.1 x (specified accuracy)/ °C (<18 °C or> 28 °C)
Relative Humidity: 90 % (0 °C to 30 °C)
75 % (30 °C to 40 °C)
45 % (40 °C to 50 °C)
35 % (50 °C to 55 °C)
Altitude: Operating: 2,000 meters
Storage: 12,000 meters
Battery type: 9 V, NEDA 1604A or IEC 6LR61
Battery Life: 500 hrs typical with alkaline
Continuity Beeper: 4096 Hz
Vibration: Per MIL-T-PRF-28800F, Class III
Sinusoidal, Non Operating
Drop: 1 meter drop per IEC 1010-1
Enclosure: Conforms to IP-40 per IEC-529
Size (HxWxL): 3.7 cm x 8.9 - 7.8 cm x 19 cm
(1.5 in x 3.5 - 3.1 in x 6.55 in )
Weight: 365 g (12.9 oz)
EMC: V ac and A ac only: RF field = 3 V/m. Total accuracy = specified accuracy +
2.0 % of range. EN 61326-1: 1997
Surge Protection: 6 kV peak per IEC 1010-1, 1990-09
Safety: 600 V CAT III and 1000 V CAT II per ANSI/ISA-S82.01-94, UL3111-1,
CSA/CAN C22.2 No 1010.1-92, EN 61010 part 1:1993
Certifications: , ,
TUV pending

79/26
Calibration Information
4
Table 1. Specifications (cont.)
Accuracy specifications are given as: ±([% of reading] + number of least significant digits) ac readings
are ac-coupled, true rms, and are valid from 5 % to 100 % of range. Add ±(2 % of reading + 2 % of
range) for 1.4 < CF ≤maximum CF. Maximum CF is 3 full scale, 6 half scale.
Function Range Resolution Accuracy Burden Voltage (Typical)
K400.0 mV 0.1 mV ±(1.9 %+4)
(45 Hz to 1 kHz) 4.000 V 0.001 V ±(1.9 %+2)
40.00 V 0.01 V ±(1.5 %+2) Not Applicable
400.0 V 0.1 V ±(1.5 %+2)
1000 V 1 V ±(1.5 %+2)
L4.000 V 0.001 V ±(0.3 %+1)
40.00 V 0.01 V ±(0.3 %+1) Not Applicable
400.0 V 0.1 V ±(0.3 %+1)
1000 V 1 V ±(0.3 %+1)
mL*40.00 mV 0.01 mV ±(0.3 %+5) Not Applicable
400.0 mV 0.1 mV ±(0.3 %+1)
e400.0 Ω0.1 Ω±(0.4 %+2)
4.000 kΩ0.001 kΩ±(0.4 %+1)
40.00 kΩ0.01 kΩ±(0.4 %+1) Not Applicable
400.0 kΩ0.1 kΩ±(0.6 %+1)
4.000 MΩ0.001 MΩ±(0.4 %+1)
40.00 MΩ0.01 MΩ±(1 %+3)
Capacitance 99.99 nF 0.01 nF ±(1.9 %+2)**
999.9 nF 0.1 nF ±(1.9 %+2)**
9.999 µF 0.001 µF±(1.9 %+2)** Not Applicable
99.99 µF 0.01 µF±(1.9 %+2)**
999.9 µF0.1µF±(1.9 %+2)**
9999 µF1µF±10 % Typical
R400 Ω0.1Ω5 % Typical*** Not Applicable
40Ω40 Ω* 0.01 Ω5 % Typical***
(Lo-Ohms) 400 Ω0.1 Ω5 % Typical*** Not Applicable
G2.450 V 0.001 V ±2 % Typical Not Applicable
* In 40 Ωand 40 mV ranges, thermals may introduce additional errors. Maximum accuracy is obtained when
both probe tips are maintained at the same temperature.
** Accuracy applies when measuring film capacitors or better and the open lead reading is subtracted from the
measurement. This meter uses a dc-type measurement technique.
*** Accuracy applies after lead resistance compensation.

Series III Multimeter
Specifications
5
Table 1. Specifications (cont.)
Function Range Resolution Accuracy Burden Voltage (Typical)
?(45 Hz to 1 kHz) 4.000 mA 0.001 mA ±(1.5 %+4) 11 mV/mA
40.00 mA 0.01 mA ±(1.5 %+2) 11 mV/mA
4 A 0.001 A ±(1.5 %+4) 0.03 V/A
10.00 A* 0.01 A ±(1.5 %+2) 0.03 V/A
A4.000 mA 0.001 mA ±(0.5 %+5) 11 mV/mA
40.00 mA 0.01 mA ±(0.5 %+2) 11 mV/mA
4 A 0.001 A ±(0.5 %+5) 0.03 V/A
10.00 A* 0.01 A ±(0.5 %+2) 0.03 V/A
Frequency** 99.99 0.01 Hz ±(0.01 %+1)
(1 Hz to 20 kHz) 999.9 0.1 Hz ±(0.01 %+1) Not Applicable
9.999 kHz 0.001 kHz ±(0.01 %+1)
20.00 kHz 0.01 kHz ±(0.01 %+1)
* Overload, 20 A for 30 seconds
** For rectangular waveforms 25 % ≤duty cycle ≤75 % . V ac ≤1 kHz.
Frequency Counter Sensitivity and Trigger Level
Input Range* Minimum Sensitivity (RMS Sine Wave)
500 Hz to 20 kHz 1.0 Hz to 500 Hz**
400 mV ac Not Applicable Not Applicable
4 V ac 0.3 V 0.7 V
40 V ac 3 V 7 V
400 V ac 30 V 70 V
1000 V ac 300 V Not Applicable
* Maximum input for specified accuracy = 10 x Range or 600 V.
** Display rattle for sine waves below 500 Hz = 5 counts.
Function Overload
Protection* Input Impedance (Nominal ) Common Mode Rejection Ratio
(1 kΩUnbalance)
Normal Mode
Rejection
L1000 V dc
1000 V ac rms (sine) >10 MΩ, <100 pF >120 dB at dc, 50 Hz, or 60 Hz >60 dB at 50 Hz or 60 Hz
mL1000 V dc
1000 V ac rms (sine) 10 MΩ, <100 pF >120 dB at dc, 50 Hz, or 60 Hz >60 dB at 50 Hz or 60 Hz
K1000 V dc
1000 V ac rms (sine) >10 MΩ, <100 pF >60 dB, dc to 60 Hz
(ac-coupled)
eOpen Circuit
Test Voltage Full Scale Voltage Short Circuit Current
<4.0 MΩ<40 MΩ
1000 V dc,
1000 V rms (sine) <1.3 V dc <450 mV dc <1.3 V dc <250 µA
G1000 V dc,
1000 V rms (sine) <3.1 V dc 2.45 V dc 600 µA typical
*107 V-Hz max.

79/26
Calibration Information
6
Recommended Equipment
Test equipment recommended for the performance tests and calibration is listed in Table 2. If the
recommended models are not available, instruments with equivalent specifications may be used.
Table 2. Required Equipment
Equipment Minimum Specifications Recommended Model
DMM Calibrator DC Voltage: 0-600V Fluke 5100B, 5101B,
plus Transconductance Accuracy: .05 % 5102B, 5700A) + 5220A or
or Power Amplifier AC Voltage: 0 to 1000 V
Accuracy: 0.2 %
Frequency: 45 Hz to 20 kHz
DC mA: 0 to 35 mA
DCA: 0 to 10 A
Accuracy: 0.1 %
AC mA: 0 to 35 mA
ACA: 0 to 10 A
Accuracy: 0.3 %
Frequency: 45 Hz to 1 kHz
Fluke 5500A Multi-Product
Calibrator, 5700A + 5725A
Function Generator Sinewave voltage: 0 to 1 V rms
Frequency: 1 Hz to 20 kHz
Frequency Accuracy: 002 %
5500A Multi-Product Calibrator
or equivalent
Decade Resistor Resistance 0 to 35 MΩ:
Accuracy: .05 % Fluke 5500A Multi-Product Calibrator or equivalent
Decade Capacitor Capacitance: 100 pF to 1.1 µF
Accuracy: 0.5 % Fluke 5500A Multi-Product Calibrator or equivalent

Series III Multimeter
Basic Maintenance
7
Basic Maintenance
WWarning
To avoid electrical shock or personal injury, remove the test leads and any
input signals before opening the case, and close and secure the case before
operating the Meter.
To prevent damage or injury, install only specified replacement fuses with the
speed, amp interrupt rating, and voltage ratings that are shown in Table 12.
Opening the Meter Case
Refer to Figure 1, and use the following procedure to open the case:
1. Remove the test leads from any input signal.
2. Set the rotary switch to OFF and remove the test leads from the terminals.
3. Remove the four Phillips screws from the bottom case.
4. Turn the meter face up, grasp the top case, and pull it up. The top case “hinges” open from the bottom.
pdoo8f.eps
Figure 1. Opening the Case

79/26
Calibration Information
8
Replacing the Battery
WWarning
To avoid false readings, which could lead to possible electric shock or personal
injury, replace the battery as soon as the battery indicator Mappears.
The meter is powered by a single 9 V battery (NEDA 1604A/IEC 6LR61).
Refer to Figure 2, and use the following procedure to replace the battery:
1. Remove the top case as described under “Opening the Meter Case.”
2. Lift the battery from the bottom case and install the new battery.
3. Reinstall the top case as described below in “Reassembling the Meter Case.”
F2
F1
pd002f.eps
Figure 2. Replacing the Fuses and Battery
Reassembling the Meter Case
1. Verify that the rotary switch is in the OFF position.
2. Place the top case on the bottom case and snap them together.
3. Reinstall the four Phillips screws into the bottom case.
Go to “Performance Tests” later in this document, and perform the procedures described.

Series III Multimeter
Basic Maintenance
9
Testing Fuses
Refer to Figure 3, and use the following procedure to test the internal fuses of the Meter:
1. Turn the rotary switch to the ΩEposition.
2. To test the F2 fuse (11 A, 1000 V), plug a test lead into the VΩGinput terminal and touch the probe
to the 10 A input terminal.
3. The display should read between 0.1 Ωand 0.5 Ω.
If the display reads OL (overload), replace the fuse and test again. If the display reads any other value,
further servicing is required.
4. To test the F1 fuse (F44/100, 1000 V), move the probe from the 10 A input terminal to the 40 mA input
terminal.
5. The display should read between 10 Ωand 12 Ω.
If the display reads a high resistance or OL (overload), replace the fuse and test again. If the display
reads any other value, further servicing is required.
RANGE
pd001f.ep0s
Figure 3. Fuse Testing
Replacing Fuses
WWarning
To avoid possible arc blasts and injuries that result from the blasts, install only
specified replacement fuses with the speed, amp interrupt rating, and voltage
ratings that are shown in Table 12.
Refer to Figure 2, and use the following procedure to examine or replace the Meter’s fuses:
1. Remove the top case as described under “Opening the Meter Case.”
2. Remove the defective fuse by gently prying one end of the fuse loose and sliding the fuse out of the
fuse bracket.
3. Install only the specified replacement fuses with the speed, amp interrupt rating, and voltage ratings
that are shown in Table 12.

79/26
Calibration Information
10
4. Ensure that the rotary switch and circuit board switch are in the OFF position.
5. Reinstall the top case as described in “Reassembling the Meter Case.”
Replacing the Bottom Case Assembly
Caution
To avoid contamination with oil from the fingers, handle the pca by the edges
or wear gloves. PCA contamination may not cause immediate instrument
failure in controlled environments. Failures typically show up when
contaminated units are operated in humid areas.
Refer to Figure 4, and use the following procedure to remove the subassembly and replace the bottom case
assembly:
1. Remove the top case as described under “Opening the Meter Case.”
2. Remove the F2 (F11 A) fuse to access the screw that holds the subassembly to the bottom case (refer to
“Replacing Fuses”).
3. The subassembly may now be removed.
4. Install a new bottom case onto the pcb.
5. Reinstall the top case as described in “Reassembling the Meter Case.”
F2
Screw
pd006f.eps
Figure 4. Removing the Subassembly