On Tue, 3 Aug 1999, Jay West wrote:
>One major problem with my 2100A has been solved (sort of). I had a card that
>wouldn't work properly in a particular slot, finally got the bright idea to
>move it to a different slot (I'm using polled mode, not interrupt, so this
>is possible). The card works great. Problem solved? No.....
>
>In the troubleshooting process I noticed a few slots that no cards would
>quite work right in. I checked the back of the backplane (it is a hand-wired
>backplane), no loose wires, etc. After very close inspection of the
>backplane slots, I determined the problem is the contacts are
>dirty/corroded/whatever. I tried the best I could to clean the contacts
>inside the slot, but this is virtually impossible. I also cleaned the card
>edge with an eraser just to be sure. Bingo - card now works fine but only in
>the cleaned slot (or one that worked previously).
>
>So, given that it's a delicate hand-wired backplane, does anyone have any
>magic tricks for how to clean the gold contacts inside of the backplane edge
>card connectors? I'm afraid to experiment and looking for wisdom... :)
>
>Thanks!
>
>Jay West
Using an eraser is a no-no.
See
http://www.spiritone.com/~nabil/pdp8/tools.html (Tools for old computers)
for a discussion of DeoxIT and PPE (polyphenyl ether). I have some more
material on PPE from the manufacturer that will be added soon.
If it's just dirty, something like Blue Shower/Tuner-wash followed by a
PPE spray might do the trick. Look at the connectors in an unused
socket, if you can see what look likes corrosion (green corrosion, purhaps)
in little spots (sometime slightly raised), the connectors are hopelessly
destroyed, it'll never be reliable again. That sort of electrolytic
corrosion damage is very common (it's caused by microscopic defects in the
plating (or people using erasers) and the metals migrating around), and short
of replacing them, un-repairable.
--
Aaron Nabil
Received on Wed Aug 18 1999 - 22:59:52 BST