Contents
- Intro
- Disclaimer
- Initial inspection
- Diagnostics and repairs
- Manuals references
- Calibration and verification
- Summary
In this article friendly lab’s Fluke 5700A calibrator will be serviced, repaired and calibrated, so get ready for teardown and deep dive into guts of expensive device. Fluke 5700A was first introduced in 1988, and today it is already discontinued, but still valued as gold in many labs. Many of these calibrators are still actively used, and actively supported even today, 30 years after. This particular unit however in need of repair, so we will see what it takes to bring it back to life and service.
MFC like 5700A is a high precision instrument that can be used as stable source to calibrate a wide variety of electrical measurement equipment. This model functions and provided output ranges allow to test performance, calibrate and adjust nearly any handheld and benchtop multimeters with a resolution scale all the way up to 7½ digits.
Top-end meters, like 8½-digit Keysight 3458A can be also tested with 5700A series, however in this case calibrator must be characterized for true output value to provide good TUR. This MFC in most of user cases allow to replace whole range of expensive calibration standards, and can be itself calibrated by only three external artifact standards – 1Ω 10KΩ and 10V DC.
This is not official accredited repair service, xDevs.com do not provide such service for 3rd-party, this was just friendly help.
We do our best effort to follow the service procedures published by manufacturer, however everything disclosed here is for educational purposes only.
Disclaimer
Redistribution and use of this article or any images or files referenced in it, in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
- Redistributions of article must retain the above copyright notice, this list of conditions, link to this page (/fix/f5700a_u2/) and the following disclaimer.
- Redistributions of files in binary form must reproduce the above copyright notice, this list of conditions, link to this page (/fix/f5700a_u2/), and the following disclaimer in the documentation and/or other materials provided with the distribution, for example Readme file.
All information posted here is hosted just for education purposes and provided AS IS. In no event shall the author, xDevs.com site, or any other 3rd party, including Fluke be liable for any special, direct, indirect, or consequential damages or any damages whatsoever resulting from loss of use, data or profits, whether in an action of contract, negligence or other tortuous action, arising out of or in connection with the use or performance of information published here.
If you willing to contribute or add your experience regarding Fluke instruments repairs or provide extra information, you can do so following these simple instructions
-1100 and +1100VDC voltages present inside of this calibrator when operation are dangerous and even lethal. Do not service alone, and follow safety rules when making connections and probing. Do not use hand probing unless absolutely required and safety is ensured. Use tools rated for CAT III operation while servicing high-power circuits in this instrument.
Initial inspection
Manuals references
Fluke does provide all main manuals, including service information right on their product page, without requirement of any registration or access requests, unlike Tektronix or Keysight. Thumbs up for Fluke, way to host the data on your product page, not hiding behind registration forms.
Brochure: The 5700A/5720A MFC: Taking Accuracy to New Level
Fluke 5700A/5720A Series II Operator Guide, May 1996, Rev.1
Fluke 5700A/5720A Series II Operators Manual, May 1996, Rev.2
Fluke 5700A/5720A Series II Operators Manual Supplement, Feb 2008, Issue 5
Fluke 5700A/5720A Series II Operators Manual Supplement, Feb 2008, Issue 9
Fluke 5700A/5720A Series II Service Manual, Nov 2007 w/o schematics
Fluke 5700A/5720A Series II Service Manual Supplement, Issue 6
Fluke 5700A/5720A Series II Service Manual Supplement, Issue 9
Fluke 5700A/5720A Series II Getting started, March 2002, Rev.2
Fluke 5700A/5720A Series II Getting started Supplement, Issue 6
Fluke 5700A/5720A Series II Remote Programming Reference Guide
Fluke 5700A Instrument Security Procedures
Fluke 5720A Instrument Security Procedures
Fluke 5725A Instrument Security Procedures
Fluke 5725A Getting Started, April 2014
Fluke 5725A Getting Started Supplement, Issue 3
Fluke 5725A Instruction Manual, Jan 1989 Rev.7
Fluke 5725A Instruction Manual Supplement, Issue 4
Fluke 5725A Instruction manual
Tech data: 5700A->5720A Upgrade Service
Model 5440A-7002 Low Thermal Test Lead Set – Specification
Fluke 5700A, 5720A CE Declaration of Conformity
Service notes
First goes the most important document for repairs/maintenance – 570-page service manual. Credits for hosting it freely going to KO4BB portal. We are lucky to also have schematics, list of parts, assembly drawings of the boards included in it!
Fluke 5700A MFC Service Manual with schematics, Rev.9,3/96, March 1996
Fluke 5700A Series II/5720A MFC Service Manual with schematics, Rev.1,3/02, June 1996
5700A Series I and 5700A/5720A Series II difference
According to An evaluation of the 5700A Series II Artifact Calibration document, major change in Fluke 5700A/5720A Series II are related to Artifact Calibration and high-frequency AC voltage. Artifact Calibration was improved on a number of ranges, to minimize biases. A new interpolation algorithm is also used for lower ACI ranges. Digital processor board A20 and it’s firmware was changed as a result.
From hardware standpoint, Model 5720/5700 Series II calibrator has a modification to the in-guard microprocessor circuitry and firmware to minimize noise in the low millivolt DC ranges. Also, because of the tighter specifications of the 5720A, there are more selected components in the calibrator circuitry, than in the 5700A Series I. Lot of circuit tweaks and changes are on A11 REFDAC and A16 Power Amplifier inguard assembly modules.
Diagnostics and repairs
This test graph shows 1mA output (2.2mA range), but all other ranges behave exactly the same as well. Culprit was A7 board.
Calibration and verification
Artifact calibration was performed using 10V solid-state zener standards and resistance standards.
Further verification was performed against well tested HP 3458A DMM.
AC voltage was inter-compared and tested with Wavetek 4920M.
Summary and conclusion
Unit was repaired, and verified for proper operation and stable output on all key ranges and functions over few month period.
Modified: Aug. 23, 2024, 6:15 a.m.