Restoring rubber keyboard on a logic analyzer
paulkoning at comcast.net
Sun Apr 29 12:28:18 CDT 2018
> On Apr 26, 2018, at 12:32 PM, Electronics Plus via cctalk <cctalk at classiccmp.org> wrote:
> Easier solution is to apply some conductive light lube. Radio Shack used to
> carry it, and I repaired a LOT of remote controls with it!
I made a successful repair. Here are the steps I used:
As I mentioned, I tried cleaning with isopropyl alcohol, without much success.
I realized that I could test the rubber contact points with a multimeter, probing two spots on the surface. The offending keys had much higher resistance or simply tested open. That made it easier to try other options without having to assemble/disassemble each time.
I found a spray can of "contact cleaner/lubricant" and tried that. OOPS. Made it much worse. Looked at the ingredients: one is "mineral oil". Ok, so that's fine for metal wiping contacts I suppose, but not for this. Washed the keypad thoroughly with dishwashing soap and water, then wiped several times with alcohol, that got me back to where I was.
Then I realized I still have a tube of powdered graphite (the stuff sometimes used for lubricating locks, though it turns out that's not a good idea. Squirted some onto a Q-tip and rubbed the bad contact pads with that. They look shiny as a result rather than dull black. But it works!
So that's the answer: graphite powder. I now have a working analyzer again. It will be interesting to see if the graphite wears off eventually, I suppose it might but that's ok, I can just do it again.
Thanks everyone for the suggestions.
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