On May 29, 3:25 pm, Rob wrote:

Have you tried Google?

I certainly did. The answer I was looking for was that DMMs have
effectively infinite impedance when measuring voltage and would not
discharge a capacitor when connected across it.

The answer you were "looking for", or the actual answer? And since
when is impedance to be taken for resistance?

Luckily, the Flukes should have internal fuses and should *just* be
able to accept a charge from a small electrolytic cap without
permanent damage. Capacitors will deliver a near-infinite amount of
*current* for a very brief period... the bigger the cap, the ever-
closer-to-infinite-current it will deliver. Can you say OUCH!!

I am not quite sure what your point is after all. Are you attempting
to test the quality of the cap? The voltage in the circuit? Both?
Neither? If you are attempting to test a cap, you need a cap tester.
Preferably one that will test the cap at full operating voltage. After
that, an ESR meter. Short of this, a VOM will only just barely test a
cap, and only after full discharge and only then on the Ohms setting
for internal resistance, and only then to an _extremely_ limited
degree with results that are only just better than none at all.

I keep a very nice Fluke with an internal capacitance checker... this
measures capacity only with leakage (on electrolytics) tending to show
up as excess capacitance. In the field, it is better than nothing, and
it is very useful testing new caps when precision values are required.
But when I am testing electrolytics, a meter that will test at full
voltage is the only way to fly.

Peter Wieck
Wyncote, PA