PDP-8/a cleaning

Philipp Hachtmann hachti at hachti.de
Tue Apr 25 10:42:00 CDT 2017

Hi Pontus,

I reply to the original post, but I have read many funny comments. None 
of them I considered harmful.

> My PDP-8/A is up for restoration. More specifically and 8A100 according
> to it's ID plate. It is in overall "ok" shape but oh so dusty.

> I'd like to give it a good cleaning so I'm tearing it down. And I'm
> looking for suggestion to cleaning the backplane and regulator board.
Most important: Get away any possible residues of foam (don't know if 
there's foam in an 8/a, but 8/e has).

> I'm considering putting the Omnibus part under warm water and perhaps a
> bit of mild detergent.
Wash it, rub it, scrub it, dry it! I see no problem.

> Should I get distilled water or will tap do? The
> water here is not very "hard"

All those distilled water/alcohol/etc. tricks are not very relevant for 
your backplane. Dry it well. Compressed air can help. Ignore the 
compressor/oil discussion on that kind of application.

The complicated rinsing and drying gets more interesting with high 
impedance electronics.
I have an ISDN phone that I used in the tub too much :-) It started to 
think eventually that all buttons are pressed the same time. To get that 
going again, I needed a sequence of vinegar -> hot water -> distilled 
water -> alcohol.

> The regulator backplane has a relay and a button which will never dry
> out if I soak it...
I would pull the relay before washing. And never put relays into an 
ultrasonic cleaner - even when they are sealed and approved to be washed!

One sad thing about washing minicomputer pieces is that you most 
probably lose or at least damage any original paper labels.

Kind regards


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