Not a project, but wanted to share something I did the other day.
Emma, my trusty Model M keyboard has been ill with a case of rotten membrane contacts since the day I was given her for free. Some conductive ink helped mitigate it, but without a proper method to paint the traces decently and a good quality ink, this was only a temporary (albeit long-lasting) solution.
I tried a few last-resort methods of exposing the traces underneath the conformal coating before retiring her, which is why it looks even worse for the wear in this shot. While I haven't fully given up on her yet, I needed a temporary substitute.
Meet Marlena, Emma's younger sister. Despite being an M2 keyboard, sadly she's rubber dome and not buckling spring. Still, she feels like a fair substitute to her older sister. I rescued Marlena years ago from being tossed away from a hackerspace I worked at. The problem is she seemed just as reluctant to work So as Emma, so now I have two defective keyboards on my hands...
So I started to take Marlena apart, and in doing so I found some interesting cost-cutting methods I'd never seen in a keyboard before. Where metal braces would be on longer-width keys such as spacebar and backspace, Lexmark molded plastic springs instead. Except for the enter key, which had the standard metal brace for some reason, go figure.
Time for a well-earned bath... the keyboard had seen better days, I never properly cared for it since I rescued it years ago (which is why I never noticed it wasn't working). I thought it was only dirt keeping it from working right, but there was more to it than met the eye...
When I put everything back together once it was dry, half the keys still wouldn't work. In fact even with a clean membrane underneath, pushing on it directly without the rubber layer, some keys showed no sign of working at all... until I pushed down on the PCB. Ah. These membranes connect to the edge bus on a controller PCB through pressure alone, and on Marlene's case, this was provided by a piece of foam that was long since gone into mushy hell. First, I cleaned the contacts on the edge of the membrane, and then padded the space under them with a few bits of cardstock, which properly pushed them together.