Electrolytics and Old Caps

[Nick England]

Something in me really likes keeping equipment in original shape if possible.
Since it is usually impossible to find the right multi-section electrolytic can
these days, you end up squeezing in several modern axials as a substitute.
And if the electrolytic was rated at 500v or 525v, you'll probably have to use
two lower-voltage modern caps. So - one old multi-section can = 3 or 4 modern
axials. You can either stuff them under the chassis (adding a terminal strip)
or possibly in the old can.

However, I have found that most old electrolytic cans from the 50's and early
60's will reform just fine. Ditto for NOS cans that I have found at hamfests. I
limit the re-forming current, take my time, and I measure leakage and
capacitance when I'm done. I have been very satisfied with this procedure and
have saved many pieces of ham and hi-fi gear. If the cap won't re-form to
original spec, OK I replace it - but more often than not I don't have to.

On the other hand, my experience has been that most old axial electrolytics
aren't up to snuff and usually won't reform. So they get replaced if out of
spec.

No, this isn't how I'd do it if I was in the radio repair business - but I'm
not. I restore and operate old equipment because I personally enjoy the process
and the results. I know what I am doing - I'm an electronics design engineer
who has been working on tube gear for over 40 years. Part of my pleasure comes
from keeping as much original as possible out of admiration for the engineers
at Heath and elsewhere who designed this gear so long ago. I am sure none of
the computer hardware I have designed will be in use 40 years from now!

Just another perspective.
best regards to all,
Nick KD4CPL

----- Original Message -----
From: "Malcolm Leonard" <radiorepair at MINDSPRING.COM>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Monday, August 02, 2004 1:03 PM
Subject: Re: Electrolytics and Old Caps


> Mike,
> Yours are words of wisdom!No good service tech would dream of charging
> anybody to refurbish any piece of gear twenty years or older without
> replacing at least the electrolytics.
> Time and again,leakage tests on old lytics have proven they were out of
> spec.You can't get good sound or any other top notch performance parameter
> with leaky caps in any electronic device.
> .Do it according to good,solid,proven science or don't do it at all!
> Malcolm

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