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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

W

Warning

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:  +31 402-678-200
Japan:  +81-3-3434-0181
Singapore:  +65-738-5655
Anywhere in the world:  +1-425-446-5500

For additional information about Fluke, its products, and services, visit Fluke’s web site at:

www.fluke.com

Summary of Contents for 26 III

Page 1: ...eter 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 warran...

Page 2: ...l 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 term...

Page 3: ... 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 Confo...

Page 4: ...mV 0 3 1 e 400 0 Ω 0 1 Ω 0 4 2 4 000 kΩ 0 001 kΩ 0 4 1 40 00 kΩ 0 01 kΩ 0 4 1 Not Applicable 400 0 kΩ 0 1 kΩ 0 6 1 4 000 MΩ 0 001 MΩ 0 4 1 40 00 MΩ 0 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 µF 0 1 µF 1 9 2 9999 µF 1 µF 10 Typical R 400 Ω 0 1Ω 5 Typical Not Applicable 40Ω 40 Ω 0 01 Ω 5 Typical Lo Ohms 400...

Page 5: ...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 kΩ Unbalance Normal Mode Rejection ...

Page 6: ...B 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 equivalen...

Page 7: ...ement 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...

Page 8: ... 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 th...

Page 9: ... between 10 Ω and 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 W Warning 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...

Page 10: ...led 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 sub...

Page 11: ... single Phillips screw underneath the fuse Lift out the LCD subassembly from the bottom case 3 Remove the mask by inserting a small screwdriver under the edges and gently pry the mask from the snaps Lift out the LCD 4 Before installing a new LCD make sure that all connector contact points are clean Refer to Cleaning for more information 5 The LCD has a bump on the right edge When replacing the LCD...

Page 12: ...Meter and check the accuracy of each meter function against the Meter s specifications i e calibration If the instrument fails any part of the test calibration adjustment and or repair is indicated In the performance tests the Meter is referred to as the unit under test UUT Setup WWarning To prevent arc blast and possible injuries install only specified replacement fuses with the speed amp interru...

Page 13: ... V short 0 to 001 V dc 2 4 V 3 5 V 3 488 to 3 512 V dc 3 4 V 3 5 V 3 488 to 3 512 V dc and within 2 counts of 3 5 V reading 4 40 V 35 V 34 88 to 35 12 V dc 5 400 V 350 V 348 8 to 351 2 V dc 6 1000 V 1000 V 996 to 1004 V dc Testing the mV DC Function 1 Set the UUT to mL mV dc and connect the dc voltage calibrator output to the VΩG and COM input terminals of the UUT 2 Referring to Table 4 set the dc...

Page 14: ... Voltage Test Step Range Voltage Freq Display Reading 1 400 mV 20 mV 100 Hz 19 2 to 20 8 mV ac 2 400 mV 350 mV 100 Hz 343 0 to 357 0 mV ac 3 400 mV 350 mV 1 kHz 343 0 to 357 0 mV ac 4 4 V 200 mV 100 Hz 194 to 206 V ac 5 4 V 3 5 V 100 Hz 3 432 to 3 569 V ac 6 4 V 3 5 V 1 kHz 3 432 to 3 569 V ac 7 40 V 35 V 1 kHz 34 46 to 35 55 V ac 8 400 V 350 V 1 kHz 344 6 to 355 5 V ac 9 1000 V 1000 V 1 kHz 983 t...

Page 15: ... MΩ 10 MΩ 9 87 to 10 13 MΩ Decades of 1 9 2 400 Ω 190 Ω 189 0 to 191 0 Ω plus 0 reading 3 4 kΩ 1 9 kΩ 1 891 to 1 909 kΩ 4 40 kΩ 19 kΩ 18 91 to 19 09 kΩ 5 400 kΩ 190 kΩ 188 8 to 191 2 kΩ 6 4 MΩ 1 9 MΩ 1 891 to 1 909 MΩ 7 40 MΩ 19 MΩ 18 78 to 19 22 MΩ Decades of 3 5 2 400 Ω 350 Ω 348 4 to 351 6 Ω plus 0 reading 3 4 kΩ 3 5 kΩ 3 485 to 3 515 kΩ 4 40 kΩ 35 kΩ 34 85 to 35 15 kΩ 5 400 kΩ 350 kΩ 347 8 to ...

Page 16: ... 3 1000 nF 800 nF 784 6 to 815 4 nF 4 10 µF 1 1 µF 1 077 to 1 123 µF Conducting performance tests of the 400 Ω 4 kΩ 40 kΩ and 10 µF ranges verifies that the discrete and integrated circuitry needed to support the other capacitance ranges are working within specifications Therefore these tests indirectly verify that the meter will meet specification in the 10 µF 100 µF 1000 µF and 10 000 µF ranges ...

Page 17: ... limits shown Table 10 mA DC and AC Test Step Range A Freq Display Reading 1 40 mA dc 35 mA 34 80 to 35 20 dc Note To enter mA ac press the yellow button 2 40 mA ac 35 mA 1 kHz 34 45 to 35 55 ac 4 Set the output of the current calibrator to standby and connect it to the 10 A and COM input terminals of the UUT 5 Return the UUT to A dc 6 Set the current calibrator to the output shown in Table 11 and...

Page 18: ...alibrator to the VΩG and COM input terminals of the UUT 4 Set the dc voltage calibrator for an output of 3 5 V dc 5 The UUT should display 3 500 V dc 0 001 If necessary remove the four case screws and top cover and adjust R21 to obtain the proper display 6 Set the UUT to the K function and set the source for an output of 3 500 V ac at 100 Hz 7 The UUT should display 3 500 V ac 0 002 If necessary r...

Page 19: ...displayed 8 Verify the UUT reads 0 2 Ω 9 Set the decade box to 40 Ω 10 Note the difference between the displayed resistance on the UUT and 40 Ω This value will be used in step 12 11 Set the decade box to 200 MΩ 12 Multiply the value from step 10 by 017 13 If the measured value in step 10 was greater than 40 Ω decrease the measured voltage on the Meter by the calculated value from step 12 by adjust...

Page 20: ...0 VAC DC Min Interrupt Rating 17 kA 943121 943118 1 1 BT1 Battery 9 V Alkaline NEDA 1604A IEC 6LR61 614487 1 U5 LCD 686417 1 MP21 MP22 Connection Elastomeric LCD to PCA 650264 1 H7 10 Screws Case 832246 4 H2 6 Screws PCA to subassembly 448456 4 H1 Screw Subassembly to bottom case 519116 1 MP5 Tilt Stand 648961 1 MP4 Probe Holder 648748 1 S2 Keypad 649290 1 F1 F2 Top Case Assembly BT1 U5 S2 H7 10 4...

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