deskthority

Long time lurker, first time poster. I got a cheap Model M that needs some significant attention. When I got it, the arrow keys, page up, page down, and the b and n keys did not register. It was also filthy. That's easy enough to clean up, but I'm trying to diagnose the problem with the keys. I have taken everything apart, and I need to more carefully continuity check the membranes, but so far I can't find a problem near the malfunctioning keys. I'm wondering if it could be an issue with the connection to the controller. It has the integrated LED/controller above the number keys. When I got it apart, only one membrane was pressure affixed under the board, the other was not. I'm not sure how it was making any connection. I don't have a great picture of that, I can get one later if it's helpful.

I haven't been able to see great pictures of how this is SUPPOSED to work, but I assume both membranes fold over and are held with pressure against the pads on the controller board. I haven't found a good way to remove the board, I'm afraid of breaking the plastic. Any tips there? I also need to replace the LEDs, all of which seem to have been smashed.

Thanks for any advice!

One of the M's i got also has this smaller controller, it was also a bit of a puzzle for me how to take it out but eventually i figured it out and it's very simple, i found it's easier to explain with a video so i hope this helps:

This is a very cheapified version of the keyboard, and the they intend on the pressure from the small strip of foam to spread out and just press the foils to the contacts on the controller pcb. I guess over time it sort of flattens and stops working. Maybe you could replace it with a new strip of simmilar foam to fix your issues, also try cleaning up the foils with soft eraser, to remove some of the dark oxidation. For fixing the traces on the foils i found what works best is "silver conductive paint", that stuff meant for fixing TV remotes. Good luck!

Thanks, I have gotten that clip off, I was just afraid to apply too much pressure on the pegs on the bottom. Looks like I should just try wiggling it some.

Good thing I didn't pay squat for it, seems as far as Model Ms go I got what I paid for.

Am I right that both layers tuck on top of each other against the board?