I've finally gotten one of my PDP-8/Ls back on its feet - the solution:
remove *all* the cards, hose down the backplane with contact cleaner and
clean each and every finger of each and every card. The hit-and-miss stuff
just wasn't cutting it, nor was alcohol. I don't know what's in the contact
cleaner, but I have a small case of it I aquired from a now-defunct Commodore
Dealer here in town (there are *no* ingredients on the label, nor any
references to MSDS sheets, so it must be old).
As a bonus, I set up a tripod and an 8mm camcorder and took 1 second shots
between each card insertion. I now have a 1.75 minute time-lapse movie of
the cards popping in, one by one. What I _don't_ have is a way to digitize
the movie. :-(
When all was done, I fired up the machine and it ran the following program
the first time:
0020 7604 LSW / Clear accumulator and OR in the Switch REgister
0021 5020 JMP 0020 / Do it again
Core is fine, power fail/restart is fine, all the front panel switches appear
to be fine. This machine hasn't worked right for *years*. A good stiff
cleaning is all it took. Now, on to TTY tests and eventually, MAINDECs.
One gotcha with this box - one of the fuse holders is loose at the back of
the PSU. In its untightened state, it produces an open circuit if I move
the box around and don't wiggle it back to its groove. I may need to remove
most of the cards to remove the PSU to get to the nut. <sigh>.
One down, two to go.
-ethan
=====
Infinet has been sold. The domain is going away in February.
Please send all replies to
erd_at_iname.com
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Received on Fri Dec 10 1999 - 22:30:44 GMT