How to revive a PDP-8e/f/m
- STOP! Do not re-insert any removed card. Don't take out any
cards with the idea of "looking at them" and then putting them
back in. If you have already removed some, leave them out.
- Remove the lid. Scrape the crumbly foam into the trash. Use
De-solve-it to gooify the adhesive that is left and scrape it off with a
plastic scraper. Clean the lid thoroughly.
- Write down the card numbers and locations, remove the cards and store
safely. Note the locations and orientations of those little top
connector blocks. Note the colors of the wires and where they go.
- Vacuum out the crumbly bits from the backplane and the rest of the
chassis. Dust the insides out, get all the bits.
- Undo the 2 hex head screws holding the knob on, remove. Remove the 4
bezel screws, remove the bezel and front cover. Undo the two screws
holding the front panel in, remove the wire(s), unplug it.
- Undo the power harness to the backplane, remove the hex screws holding the
backplane(s) down and remove them, remove the backplace(s).
- Pick up the foam pad under from the underside of the backplane (it
shouldn't be glued down), discard and vacuum again.
- Take the backplanes over to your sink. Invert them (ie, upside down)
and use your faucet squirter to spray into them (while upside down) to flush
out debris. Removing the tape that circles the backplane pins will
greatly aid in washing and drying, you can always replace it later with
black electrical tape if desired.
- Allow the backplane to drip-dry for a few minutes. Pour about 2
liters of 99% isopropyl alcohol into a shallow tray and submerge and slosh
around the backplane. Remove, shake off, dry thoroughly in warm air (a
hair dryer works well, or a convection oven).
- Examine dry backplane with flashlight and magnifying glass, pick out any remaining
bits of debris or fluff. If you see green corrosion on the contacts,
it's probably a lost cause, it will never work reliably. Sell it on
Ebay as "as is" ;-).
- Clean and dry those little top connect blocks exactly as above.
- Examine boards. If very dirty or exposed to corrosive atmosphere or
salt spray, consider cleaning, it's easy to do now. Simply wash in
water with your little squirter hose, drip dry, dunk in alcohol, dry thoroughly
in warm air. DO NOT CLEAN THE CORE PLANE. Examine gold
fingers, clean any gunk off. Green corrosion is a bad sign. Look
for component damage, in particular exploded or deformed electrolytic caps.
- Re-assemble after everything is dry.
- Have halon fire extinguisher handy.
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