Fluke T5-1000

Thread Starter

eyesee

Joined Oct 19, 2013
60
I'm trying to repair a Fluke T5-1000 current clamp meter.

There appears to be remnants of leaked batteries on some components.

When I temporarily attached the back cover back on to test the meter after cleaning, I noticed a burning smell when the probes were connected to mains (230V AC).

The burning seems to have come from a short across the PCB from the battery negative contact to one of the thermistor contacts. What is the purpose of the thermistor and could a loose battery connection have caused the burnt short?
 

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Irving

Joined Jan 30, 2016
1,070
If there is corrosion on the board repair is likely to be unsuccessful. Clean as much as you can off with IPA and a stiff toothbrush. Then replace any component showing signs of damage/corrosion.

The 'thermistor' is a overcurrent protective device. Putting 230v AC on a damaged board may have damaged it further.

For your own safety this is not a rookie repair job.
 

Thread Starter

eyesee

Joined Oct 19, 2013
60
Thanks for your reply Irving.

I think mostly the trim potentiometers have a little dried battery electrolyte which is causing fluctuating readings.

I have repaired many items previously including mains powered so well aware of the dangers.

I wanted to know the purpose of the thermistor in a meter and what might have caused the arcing between tracks?

I'll scrape out the burnt section on the PCB and lacquer it.
 
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