Electronics > Repair

Tantalums in Fluke Handheld 80xx Meters


I got the aluminum electrolytic capacitors changed in the meters I have that "slipped through the cracks," and just to be sure I re-checked the others.

I noticed that some of the oldest meters, the "A" variants have tantalum capacitors.    In this application, is it necessary to change those?  If so, can I replace them with aluminum electrolytic capacitors, or should I buy new tantalum capacitors?

That's an interesting question and my thought is that you don't have to change them at all.  There have been many previous discussions on solid tantalums and I think the need for replacement or upgrading to higher voltages is not there in battery powered devices.  Supposedly tantalums were studied determined to be the most reliable type of capacitor with their primary weakness being intolerance of reverse voltages exceeding 2% of their rating.  That sort of thing happens during power up (or down) in some mains PSUs but not in a battery operated device. 

I follow the same logic based on my experience with tantalums - battery operated equipment usually does not suffer power supply transients and spikes, thus I haven't seen tantalums blow up. Naturally, if the DMM suffered a heavy fall that cracked parts inside, then all bets are off.

I had a tantalum go shorted in the switching power supply section of a Berry trunk test set, powered by a bunch of D cells. The on-off switch is after that board, so I had to frantically remove all the screws and disassemble the unit while smoke was pouring out.

I would imagine that capacitor experienced a lot more Dv/Dt than one in a DMM.

Jeff eelcr:
I always check them for shorts first, if other problems still show then troubleshoot for source.
Very few times have I needed to replace all tant's in any units. (not Fluke)


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