Greetings!
I recently attempted to restore a 1999 IBM Model M 122 keyboard I got off eBay by doing a bolt mod and wiring it to a Teensy++, but I have run into a problem:
While working on the key mapping with QMK, I've noticed that sometimes pressing one key will cause the keys around it to register too, despite not being pressed. I've tried reseating the key stems, but that doesn't seem to help. I've also noticed that the effected keys 'move', as in a key that does this might eventually stop and another one start.
This leads me to believe the membrane is what is causing the trouble. The barrel frame was pretty badly warped when I got it; the bolt mod is helping with that some, but the membrane did not lie flat when I was reassembling the board. It had large 'bubbles' in it, for lack of a better term; places where the membrane did not lie flat against the barrel frame and metal backplate. I believe this 'warping' is likely causing the membrane to make contact improperly, which I think would explain the key overlap as well as why the effected keys seem to move around the board.
I'm really hoping to get this board working, and was hoping someone had any thoughts as to potential solutions, or any thoughts about other things to look at that might be causing this problem.
Thanks!
Lukaus