Capacitor testers / testing.

[Chris Wilson]

I would like to be able to do some basic testing of capacitors, i have already landed myself with a device that has been stood for years, powers up fine, but today, after being left on for a few hours failed with what i guess may be a power supply issue, I am new to electronics, but fancy a go at fixing it myself. It cost very little, if it all goes wrong its experience I suppose. What devices are around Internationally as I am in the UK, that are known to work OK and aren't mega money? I Googled capacitor testing and there are dozens of opinions on ways to do it. I have a half decent hand held multimeter, and a bench multimeter, but neither have a built in capacitance testing setup. I also read of using a scope and a frequency generator, and look at the DC offset, but it sounds a bit involved, although I do have a basic scope and a cheap signal generator.  Thanks

[Mint.]

Bump. Interested

[IanB]

I think people here will be better able to help you if you can be more specific about what aspects you want to test and what your goals are?

For instance do you want to do a basic test for capacity? Test for ESR? Test for leakage? Do you want to identify unknown capacitors, or look for faults in existing capacitors? Etc...

[kripton2035]

go to my web site and pickup and build yourself an esr meter
so you will be able to detect 99% of faulty capacitors, especially in power supplies
http://kripton2035.free.fr/esr-repository.html

[Rerouter]

Now just as a starting point if you pretty much only have a multimeter,
99.9% of the time if a capacitor has failed, it is an electrolytic or a tantalum

both can be given the same basic checks, but these are just crude checks which test the most basic operation

1. on ohms setting, measure across the legs of the capacitor, while there may be some components in parrellel with it, the value should not be a short,

2. using the diode test, hold your leads to the legs of the capacitor (IN THE CORRECT POLARITY) and wait until the value seems to level out, then switch to voltage and see that its holding somewhere near 2.2-3V (depending on value it will start discharging through the multimeter, and may seem to drop like a rock for less than 100n)

but yeah if you can, an esr meter is a much better tool to find problems, those checks are only as a starting point