Frank Dresser wrote:

OK, I'll grab some of those old Ducatis and check 'em. I'm
sure they haven't seen a polorizing voltage in at least 25
years, because that's when I bought them as surplus.

Then I'll run 'em up to their rated voltage for 24 hours and
recheck.

I'll see how much extra voltage they take and hold them at
that voltage for another 24 hours.

Just for curiosity, I'll also check the ESR at each step
with my Dick Smith meter.

I know none of this is lab quality procedure, but if there's
any gross changes, I think I'll catch 'em.

Frank Dresser



That would be fine if you are looking to get doused with electrolyte.
A better test would be to measure the capacitance as they sit.
Then reform them with a 1.5K resistor in series with the supply.
Then retake the measurements.

If the cap isn't drawing current during the reform, it means the
maker got the electrolyte formulation right, you probably won't see
much change in measured characteristics. If the cap is drawing
heavy current during the reform, you should see greater differences
in the reformed cap vs the "NOS" cap. ESR should go down, capacitance
should go down, and so should leakage current.

-Chuck, WA3UQV