Re: Electrolytic caps and Apple analog circuits (semi on topic)

["Michael J. Mahon" <mjmahon@aol.com>]

jsnospam@cimmeri.com wrote:
> > Absorbing moisture from the air would be a serious problem, since
> > then they could absorb other things that would poison the electrolyte.
>
>
> Michael, one of the passages (at least) I came across on this odd air
> absorption claim:
>
>
> From: "Barry Ornitz" <ornitz@dpnet.net>
> Newsgroups: rec.radio.amateur.homebrew
> Subject: Re: How to form an old electrolytic ?
> Date: Wed, 13 Dec 2000 02:01:08 -0500
>
> If the electrolytic is a wet, or liquid filled electrolytic from
> before
> 1940, you may have to add distilled water.  Most electrolytics made
> after
> WWII are the "dry" type which are actually made with a paste
> electrolyte.
> The paste contains materials such as propylene glycol, sorbitol, etc.
> that
> absorb moisture from the air to keep the electrolyte moist.  So if the
> unit
> has been stored in an extremely dry place, let it set a few days in a
> typical home environment to re-moisten.  [Most electronic components
> store best when kept extremely dry.  Electrolytic capacitors are the
> exception.]

I regard this as anomalous.  If storing a capacitor in high humidity
"fixes" it, then it (or more precisely, its seal) is, by definition,
"broken".

The enemy is heat, not low humidity, and a properly sealed capacitor
(one made since the 1950s) should not have a problem with a dry
environment.

It is true that most electrolyte materials are hygroscopic, but that
is only an issue when they have leaked out of a failing capacitor and
attract moisture in the process of corroding a PC board.

-michael

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