I find leaky caps that test fine for ESR all the time. If they are mounted
so that you can't see the legs, which most larger caps are, you have to
perform the "smell" test or remove them to inspect them. The smell test
consists of heating the legs and noting whether you smell bad tuna or not.

When in doubt replace. A few caps is not worth the time to have to go back
into the unit a second time.

Leonard

"larrymoencurly" wrote in message
om...
If an electrolytic capacitor tests out OK with an ESR meter, is it
normal for it to go bad (high ESR, bulging) just two weeks later, even
if it's one of those Taiwan brands that was made with defective
electrolyte?

I noticed that my computer's 2-3 year old 300W Antec power supply had
a leaking electrolytic, so I replaced it and checked ESRs of all the
other caps. They all measured less than 0.05 ohm (out of circuit --
too many in parallel), with no leaks or bulges, the bad one about 0.6
ohm. Two weeks later, I just happen to have the power supply apart
(no problems with it) and see that one of the capacitors that tested
OK is now bulging, and its ESR is 0.15 ohm. This computer isn't a
power hog but draws only 50W or so (1A @ +12V, the rest from +5V), and
I don't think the power useage or temperature have changed recently.