Ideas for repairing sad Model M with issue registering keys

[pixelheresy]

Just got a whole bunch of cool stuff from Woden as a part of the Rabbithole kit, since being new to mechanical keyboards, only had a few new and old boards of the Cherry MX/clone variety.

So I got the package yesterday and immediately fell in love with the Blue Label Model M. It was dirty but not too beat up and the back plate only had one plastic rivet popped and that on the outside corner not close to any keys (closer to the controller board). Testing it quickly with PS/2, some columns of keys (likely all on the same scan row) didn't register, but figured once I cleaned things up, it would be good.

So I cleaned up the case, the keycaps, etc. over lunch at work and it looked brilliant. New even, which was impressive for a filthy, over 20 year old board. I took it home and last night, cleaned up the contacts on the controller board and wired in a ProMicro with Soarer's flashed to it. Tested it out and it looked to work, so I buttoned up the case.

I then took it over to my desk to play with it and realized quickly that the same keys still were failing. So I opened it up and cleaned the (sparkling) contacts again. Nope. No improvement. Did some quick continuity tests on the controller board. Looked ok. Didn't seem like a crack there, or at least anywhere apparent.

The barrel plate was gooey in some places (including where one dead line is near the E and C) but no sign of anything in the barrels themselves. Offhand, it's F2, F3, 3, E, D, C, Ctl, Alt, Left, Up, Right, Num 0, Num 2, etc. So clearly something not registering on the membrane right? The backplate and plastic rivers are pristine, so no *really* wanting to perform a bolt mod if there is something else to try first. Also, from searching around, if traces are damaged or corroded, repairing is tricky. Since I live outside the US, ordering a replacement (if it is a bad membrane) entails paying shipping far and above the $10 replacement part.

Any suggestions? Especially ones to try prior to popping all the virgin rivets. Or am I looking at a membrane replacement (which as noted may prove more expensive than another board that functions, perhaps in worse cosmetic condition, since the case and caps I have look good as new).

Willing try try anything. Hell, at this point willing to soak the barrel plate assembly (sans keys and PCB). Know that is generally bad, but limited options.

[wobbled]

That's a hell of a lot of keys that aren't registering. Have you tried removing the spring and pushing down on the flipper to see if you can get the key to register? If you can then it may just need the spring reseating. If you can't then it may be worth opening up the board completely and cleaning the membrane the best you can and making sure the flippers are seated correctly. If that doesn't fix it you may just have to order a replacement membrane from unicomp or someone on here that may have a spare part.

That's what I'd do anyway, perhaps other people will have more ideas.

Good luck!

[pixelheresy]

That's a hell of a lot of keys that aren't registering. Have you tried removing the spring and pushing down on the flipper to see if you can get the key to register? If you can then it may just need the spring reseating. If you can't then it may be worth opening up the board completely and cleaning the membrane the best you can and making sure the flippers are seated correctly. If that doesn't fix it you may just have to order a replacement membrane from unicomp or someone on here that may have a spare part.

Yeah. Tried depressing the hammers and no. Nothing on those keys. Didn't remove the springs, but that's not a great idea anyway, right?

[wobbled]

Springs are easy to re-seat once you get the hang of it. Just put it on the end of a small screw driver and push it back on to the flipper and twist it on. After a few tries it should be seated properly. If you pull up on the spring and flipper and then push it back down does that do anything? Have a play about with it see if you can get anything to register. If you can then the membrane might be perfectly fine and you'll be in luck.

[pixelheresy]

Was able to trigger some working keys with a dental pick (with the key off) with a little fiddling and probing for the right spot, but was unable to get any response from the dead ones. Feels like the flipper moves somewhat but nothing registers.

[wobbled]

Was able to trigger some working keys with a dental pick (with the key off) with a little fiddling and probing for the right spot, but was unable to get any response from the dead ones. Feels like the flipper moves somewhat but nothing registers.

May be worth taking it completely apart, cleaning everything and re-assembling it but to me it's looking like a crapped out membrane.

[giokkk]

I've faced the same issue a while ago pixelheresy, wobbled was right, a crapped out membrane.
I solved with a new membrane, you have to take the keyboard apart.

Here is an excellent guide from madhias:

http://deskthority.net/workshop-f7/ibm- ... t9169.html

[pixelheresy]

Yup... No doubt.

Got back from a little weekend trip for Midsommar with the family and opened the bad-boy up. There was (even though I didn't see anything in the barrels) quite a bit of gunky stuff on top of and inbetween the membranes in some places. The in between looked like it seeped from the top. My guess is Cokepocolypse happened at some point and efforts may have been made to clean up somewhat inside, since I didn't see anything on the bottom case, just some sticky on the barrel plate. Or else, it continued to function for a while and eventually corroded.

Either way, cleaned it up and the membranes looked hazy in some places, but didn't look bad after. That it until I took a meter to test continuity. Whatever that stuff was, it seems to have damaged the membranes and the traces on them enough to cause them to be anywhere from non-functioning to touchy.

Anyway, yeah, the membrane is toast. Thanks for answering though!