On Thu, 2008-06-26 at 16:18 -0700, Jim WA9YSD wrote:
> The R.L.Drake L7 amp power supply had the same issues. The same for their
> other amps. My L-7 amp was no different.
>
> What I did was buying some computer grade caps put them in series with
> equalizing resistors. I all so added the SB-200 kit that ramped the input
> power supply voltage slowly to prevent the shock of the in rush when first
> turning it on. This totally defies the authentic value of the equipment in
> its original restoration shape. Sure worked well, and did not have the caps
> blowing.
>
Computer grade caps were made with higher purity in the aluminum foil so
bad spots didn't happen as often and they were also made to handle lots
of ripple current.
> It is characteristic for electrolytic caps to go cause they dry out. Even
> the USA made ones. I had to replace many in tube type radios and TVs cause
> the heat generated from the tubes would dry them out.
>
But electrolytics fail fastest when not used. The electrolytic eats away
at the insulating film. In ordinary operation that insulating film on
the aluminum foil is maintained by the operating voltage. At the least
new old stock and unused capacitors need to be reformed. Having failed
at that a few times that lead to blown up capacitors, I'm very picky
about the age of what I buy as NEW. If it can't read the date code, I
buy some other product. If I can read the date code and its more than a
year old, I buy some other product. Sticking to that, I've not had to
clean shredded foil and electrolyte soaked crepe paper out of a chassis
in decades.
> Keep The Faith, Jim K9TF/WA9YSD
>
73, Jerry, K0CQ
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