PDP 11 gear finally moved

Michael Thompson michael.99.thompson at gmail.com
Wed Jul 22 07:02:23 CDT 2015

> Date: Mon, 20 Jul 2015 14:11:46 +0000
> From: tony duell <ard at p850ug1.demon.co.uk>
> Subject: RE: PDP 11 gear finally moved
> >
> > Replace - yes, *especially* if you don't have a big budget. Aluminum
> > electrolytic capacitors are CHEAP and easy to obtain. Replacement
> > semiconductors by comparison are expensive and can be quite difficult to
> > find.

The RICM ignored the sage advice from experts and reformed the
electrolytics in the PDP-12 that we are currently working on. This decision
was based on our past experience on other restorations, the lack of
replacements in the same physical size, and the very high cost of the
replacements. So far the system is behaving nicely.

We have had several spectacular failures of the AC caps with the
ferroresonant circuit in DEC power supplies. We regularly replace the AC
caps because they are available and inexpensive.

Michael Thompson

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