Electronics > Repair

Capacitor has different readings if stored upside down

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I'm working on an amplifier and have removed all of the large 100v 4700uf caps for testing outside of the board. I tested all of them last week and they were all within 20%....

The super odd thing is.... This week, while they've been sitting upside down (legs up on my desk), they all measure 1pf or 2pf. I have a brand new one, so I know the DE-5000 is correct and on the right settings.

Has anyone seen anything like this before?

Kim Christensen:
Those capacitors would have gone tits up whether they'd spent the night with their legs up or not.  ;D

In seriousness though, it's odd that they tested OK the week before and now are completely open. I guess they've got to fail sometime.

Sounds more like the test leads went open circuit. Or the capacitors have a D.C. bias fooling the meter.

- Confirm you are making good contact to the cap terminals, oxide coatings can be thicker than you think.

- Check the meter wires don't have an intermittent break in them somewhere

I have a similar situation. When carrying out measurements on the board, the capacitance tends to zero. When you unsolder it everything is back to normal. Good capacitor on the board shows 9uF out of 10.
I take measurements by R&S LCR meter.
Apparently my capacitors recover after warming up.

Try warming up yours and measure again.


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