> >>
>>> Heat and charge cycles do affect a capacitor's life, but they're
>>> not the only factors. Humans who smoke, drink, and do drugs have a
>>> shorter life than those who don't, but we all will die eventually.
>>
>> Hmmm. Not really a valid analogy!
>>
>>> I've had plenty of electros in stock go off value, become leaky,
>>> and go up in ESR just from sitting in a nice quiet bin. I don't
>>> install any cap without running through my Z meter, and I will toss
>>> an entire lot of caps if one is bad.
>>
>> I managed to find 8 electros in my bin that could used in parallel
>> to get the equivalent of the failed ones I've removed. I've checked
>> them all for ESR, leakage and Capacitance and the readings I've got
>> have come out indistinguishable from new caps of the same value &
>> voltage rating. I've picked the best 6 (with the lowest ESR) and am
>> re-forming them over the course of this weekend.
>> I'll report back in due course on the success (or failure) of this
>> method. I certainly wouldn't want to hit them with their rated
>> voltage straight away after so long in limbo as that *would* be
>> inviting disaster.
>
> The final test is leakage, set the cap up with an ammeter in series
> and put it on a power supply running around 75% of the rated maximum
> voltage. Leakage should be very low after the cap has stabilized.
>
> Here is a nice write-up:
>
>
formatting link
>
> Heathkit made a great cap checker that we use to check older off the
> shelf NOS caps. Has the Magic-Eye tube and everything - except ESR.
Thanks for that link.