ESR Meter Recommendations

Chris Elmquist chrise at
Wed Sep 30 13:35:39 CDT 2015

On Wednesday (09/30/2015 at 10:54AM -0700), John Robertson wrote:
> As for testing large capacitors, about the highest value that gives useful
> readings is around 10,000ufd. Larger than that and the ESR is too close to
> zero ohms unless the cap is really bad...

And that seems to be the usual situation for most ESR meters.  How are
folks testing the very large electrolytics in the 25,000, 80,000 or even
100,000 uF range that are encountered in the power supplies of some of
these old machines?

One approach I use has been to isolate the supply and then fire it up
with an electronic load while looking at voltage sag and ripple on a
scope while that load is swept from min to max capability of the supply.

There is also the Sencore LC53 "Z Meter" which can test large caps up
to 200,000 uF out of circuit but these are typically a $400+ instrument
on the used market.

Chris Elmquist NØJCF

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