PDP-8/a cleaning

Pete Turnbull pete at dunnington.plus.com
Tue Apr 25 03:39:24 CDT 2017

On 25/04/2017 08:51, jim stephens via cctalk wrote:

> On 4/25/2017 12:45 AM, ben via cctech wrote:

>> I would go for distilled water, tap water could have chlorine it
>> it.

Not enough to do any harm if you dry it sensibly; besides, it's more 
likely to be choramines these days, not chlorine as such.  I'd be more 
concerned about calcium and magnesium salts if you live in a 
particularly hard-water area, but, again, just dry it sensibly.  I've 
done several backplanes with tap water, just blowing the excess water 
out with compressed air (but preferably from an oil-free compressor tank).

I'd start with a vacuum cleaner assisted by a small paintbrush, then 
wash in water with a little mild detergent.  Tap water if you live in a 
soft-water area, otherwise cheap distilled or deionised water, or from a 
dehumidifier.  Finally, blow dry.

> Good point.  Also with care, I've seen distilled water, then alcohol
> rinse (not rubbing, but pure of some sort), then air dry.  This is
> used on optics to get rid of water spotting.  The alcohol will flush
> out water that you could normally only wait out for evaporation, and
> rapidly evaporates itself w/o residue

"Little residue" would be more accurate, and some of that residue will 
be water (look up "azeotrope") - plus you need a lot of alcohol for 
something the size of a PDP-8 backplane.  Blow dry, even after an 
alcohol rinse.

Pete Turnbull

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