Andrew - thanks very much for the suggestions. We must share some ESP: I tried cleaning the two half-circles, but nothing changed. I then removed the keyboard and used a magnifying glass searching for a crack somewhere - no luck. I also used alcohol on a q-tip, but still no improvement. I didn't try cleaning the rubber cup "stud" however.
I then noticed a small area of one of the circuit traces, with a strange "yellow" color, like the metal in that area had somehow worn off. I checked for continuity and found none, but when I jumpered the bad spot with a bent paperclip, again, no improvement. That "bad" spot was nowhere near the problematic key. Alas, my backup 102 may soon be relegated to the back of the garage. Thanks Tom M. On Sun, Jul 6, 2025 at 6:27 PM Andrew Ayers <keepe...@cox.net> wrote: > I've never taken a 102's keyboard apart, nor have I seen the "insides" > like you describe them, but that little thing in the rubber cap you > mention as a "metal stud"...likely isn't metal. > > Based on keypads and other similar kinds of "button devices" I've taken > apart (remote controls, calculators, etc) - it's actually some kind of > plastic or rubber compound impregnated with carbon. It does actually > complete the circuit, as you stated. > > But I've also found when I've tried to bridge such a circuit with just a > piece of metal...getting it to work can be "finicky" - assuming in your > case it works at all, and the break isn't somewhere else. > > Cleaning of the contacts as suggested is a good step, though I don't > know if you need to necessarily use an eraser; they tend to be abrasive, > which in the case of cleaning contacts you'd think would be okay, but > realize that the metal layer of those contacts is very thin. One such > "cleaning" won't harm it, but do it enough times...hopefully that won't > be needed or necessary, of course. > > You might try just using the alcohol (and a swab), first (I have a > "thing" when cleaning things, especially if solvents and plastics are to > be involved: start with the least harmful first, then move up the chain > - that's usually either soap and water, or rubbing alcohol; end of the > chain, of course, is a right angle grinder and/or "blue wrench" and/or > BFH). > > Regardless, try also some rubbing alcohol on that little stud, as it can > sometimes get dirt and/or other deposits that can prevent the circuit > from being made. > > Good luck! > > Andrew L. Ayers > Glendale, Arizona > phoenixgarage.org > github.com/andrew-ayers >
