On Jan 14, 10:01, John Allain wrote:
> > The best way to check those #$%#$%^# caps is to use an ESR meter. And
> > only then should yo buckshot them. And replace them with good grade
>
> Seems like a simple enough question: how do you test them?
> I don't have an ESR meter, should I get one? No other way?
The quick and dirty test is to use an *analogue* meter (what Americans used
to call a VOM, not a VTVM) on the ohms range across the capacitor. The
needle should flick violently across (indicating zero or low resistance)
and then fall quickly (at first) as the capacitor charges (and the current
drops). Ideally it should end up showing virtually infinite resistance.
It needs a bit of experience, though, as the violence of the flick depends
on ESR and capacitance, and there tends to be some leakage in an
electrolytic so the final reading is often not zero current. It may be
worth trying if you have a known-good capacitor of similar voltage and
capacitance to compare.
A digital multimeter is rarely any use for this, though. The response of
the meter is just too slow; by the time it's shown the first reading the
event is all but over. Also most DMMs use very low voltages and currents,
not enough to give a big electrolytic a good fright.
--
Pete Peter Turnbull
Network Manager
University of York
Received on Mon Jan 14 2002 - 11:29:21 GMT