May 7, 2020

A. Kelvin-Varley. Voltage Divider. Instruction Manual. P/N mm (8) In the event of failure of a product covered by this warranty, John Fluke Mfg. Co., . The Fluke A Kelvin-Varley Voltage Divider generates V and 11W of power. A models provide an absolute linearity of ppm, a temperature. Find great deals for Fluke A Kelvin Varley Voltage Divider Shop with confidence on eBay!.

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Fluke A front and rear features There are no connectors, vent openings or anything else on sides and rear of the instrument. On coarse precision levels it may be possible to use this constant linear TCR value, and add simple linear correction.

If anyone knows details about this, please share.

Fluke A Kelvin Varley Voltage Divider | eBay

Teardown So now as we confirmed my unit is broken, time to remove covers and see what is inside. Of course, reason of why this article is published in repair section very simple.

Keep children and cats away during A service, with no pun intended. All other conductors within the instrument, as well as the solder employed, contain no metals or junctions that could contribute to thermal emf problems.

Contents Intro Disclaimer Exterior and overview Diagnostics and inspection Teardown Troubleshooting and repair Performance test Linearity test Conclusion Intro As was predicted not very long time agocomplete Fluke A standard got into out hands finally.

Wiring error on decade A. To achieve this ratio, calibrated HP A multimeter will be used. 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: Also PCB s are more usual modern green mask type there. Perhaps previous failed repair attempt by owner?


Internal construction of pole rotary switch, used in Dec. This KVD is fully passive device and does not generate any power or signals. Trim PCB assembly Also connection to input and output binding posts has got my attention, as soldering does not look very good. Bridge balance pot and trimmers accessible from front panel. Correct wiring from good F Maybe except screw or two… Internal switch for calibration for third decade. Internal calibration switch Little board with beautiful Fluke-made teal resistors mounted just above the oil tank from the top side.

Additional service and repairs Plastic shafts used to rotate decade switches were replaced as well.

720A Kelvin-Varley Divider

There are no connectors, vent openings or anything else on sides and rear of the instrument. The unit may be mounted in a standard inch rack.

Original ones were made of fragile acrylic plastic and cracked already: Instruction manual provide use, calibration and servicing information for the unit. Take a look on KVD conceptual schematics. Troubleshooting and repair Incorrect wiring on Decade A switch Continuity measurements 720x lack of connection from Input terminals to the beginning of Decade A resistor network.

If you willing to contribute or add your experience regarding any instruments repairs or provide extra information, you can do so following fluje simple instructions Exterior and overview Image 1: The KVD Kelvin-Varley Voltage divider employs precision resistors which have been aged, temperature and power cycled to maximize long-term stability, and matched to minimize temperature and power coefficients effects.


That reveals 40 year age of this instrument. Inside bottom side Bottom side reveals some serious touch on details, with oil-filled resistor chamber for most critical first decade A.

The single turn pots are wire wound, manufactured by CTS. Wiring around decade B. Fluke A Instruction manual. ToddlowimpedanceDr.

Markings on rotary switch and resistors If reading correct, date-code on on decade A switch is 6th weekand resistors on A trimmer board are 37th week Seven decades with position rotary switch in each allow to set 702a division ratio of an input voltage.

Bridge power and detector terminals are fpuke for calibration and linearity testing. Plastic shafts used to rotate decade switches were replaced as well. Wiring harness, all fixed in place There is also little 5K KVD -pot with co-axis fine and coarse adjustment for balancing bridge.

May the Volt be with you. Wiring error on decade A This reveals that all decade A resistors are wired incorrectly by one position counter-clockwise from switch rear view. The switches used have gold plated solid silver alloy contacts for long life, minimum contact resistance, and no tarnishing. Our unit still have old-style Fluke logo, bit yellowed switches and of course dirty connectors:. As usual with performance checks and testing, reference standard must have at least 2 better more times better uncertainty that DUT.

Schematic section of Decade A network.