On Tuesday, 18 August 2020 04:06:53 UTC+1, Ralph Mowery wrote:
In article ,
says...

** You misunderstand the purpose of such checkers- which is to test the C value or ESR vale of a GOOD cap. In order for them to work, the cap must NOT be faulty.

The C value of a leaky cap will be way off and the ESR value of a shorted cap tells you nothing.

So do an ohm meter test FIRST !!




I see what you are telling me. The way many of the capacitor checkers
work a leaky capacitor will throw them way off. I just had not even
thougt that out very well.

that is the usual result

Of course the shorted one is no use to even check that on the
capacitor checker. The China checkers will probalby tell me that I have
a resistor of zero to very low ohms.

So it's told you the cap is faulty and what's wrong with it. Sounds useful to me.

I much prefer these cheap testers to the old Heathkit. The China special gives a quick reading of C (which is indeed affected by C faults), ESR & Vloss. High R caps show up with high ESR, leaky caps show up with high Vloss, and some caps show up with C loss. The one big limitation is it only tests at 5v, but so far I've found it still picks up caps that fall over at higher voltages, ie their 5v performance isn't ok either.


NT