On 11/03/2017 02:44 PM, william degnan wrote: > Hi...I am working on a PET 2001-32B with a bad keyboard. The circuit > board is OK, the keyboard logic is OK, the computer itself is fine. I > have isolated the problem to the black carbon tips that touch the > circuit board upon a tap of a key from the keyboard. > > I have cleaned the tips with 91% isopropyl alcohol and that has had > little effect. I speculate a glaze has formed on the tips and the > conductivity has been lost. > > Should I clean "harder"? > > I have heard one should paint/brush a metallic paint onto these tips, > but I am thinking there must be a way to restore the conductivity > without adding paint, something that will lead to issues down the road. > I have also seen a page stating the solution is to scribble on the tips > with a pencil. Also not to me a good long-term solution. > > Would it make sense to simply use a pencil *eraser* on the tips instead, > or a very smooth sandpaper/file to buff them in order to clear off a > thin layer/film that may have formed? > > I figure someone here has been through this. I searched the web, > surprised to have not have found more written about this. Up to this > point I have had spare keyboards and this issue never came up. You might want to read this text then: http://plus4world.powweb.com/plus4encyclopedia/500009 It talks about restoring a plus/4 keyboard. I also heard that it'd a good idea to apply some graphite powder to the carbon tips, but I haven't tried that yet. Then there is this: https://www.amazon.com/dp/B0026PRMVM (Just found via google) Gerrit Message was sent through the cbm-hackers mailing listReceived on 2017-11-03 14:00:02
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