[sdiy] "Zerolytics"

mskala at ansuz.sooke.bc.ca mskala at ansuz.sooke.bc.ca
Tue May 5 20:08:43 CEST 2020

On Tue, 5 May 2020, Ingo Debus wrote:
> Not necessarily. I once repleced a few electrolytics in a real old radio
> (from the sixties or so). Some had become leaky but others had a much
> higher capacitance than the value printed on them.

Unless you have measurements of where they were at in the sixties, I
wouldn't conclude too much from this.  Electrolytic caps often have very
wide tolerance ranges, like -20% +100%, so if the printed value is 10000uF
and it now reads 12000uF, it could actually have started at 20000uF and
lost 40% of its initial value; or it could have started at 12000uF and
suffered no aging at all.

In my own experience, all-or-nothing kinds of failures are more typical of
electrolytics than slow gradual decline.  After ten years it might start
leaking, and then drop to 10% of its original value in the space of a few
months; or it might be still going strong after 20 years; it's not so
likely to smoothly lose 1% per year; but the world is a big place and I'm
sure that happens occasionally too.

Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before tribes.

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