Lexmark Model M - dead matrix?

[Barabbas]

I just did a "bolt mod" on my 1391412 and some keys aren't working, also NumLock LED isn't working either.



I need some advice regarding troubleshooting of the problem. I don't know
what can be the cause and where to start looking.

(I did check the connections, the matrix seems to be connected properly to the
board)

[Barabbas]

Anyway, so this board (Lexmark btw) contunues to dissapoint me on a daily basis. If only I could get my hands on an US made Model M, they are kind of rare here in Europe.

I used a piece of wire to simulate the key presses on the logic board, turns out that lines 9 and 14 are broken somewhere, I believe it is the connector (damn, I was super careful while handling it),also there is a thin black line visible on these wires, which I am trying to fix.

Does anyone have any tips about repairing the matrix? I can't solider this stuff, it's like soldering paper

[rknize]

Rear window defroster repair kit.

[rknize]

You can also order new membranes from Unicomp, but that may not make sense if you are not in the states.

[Barabbas]

You can also order new membranes from Unicomp, but that may not make sense if you are not in the states.

I already sent an email to Unicomp about that issue. But why, Is the postage that high? A new membrane assembly is only 10$:
http://pckeyboard.com/page/Misc/MEM

The window repair kit costs more than that.

In the meantime, I will try to fix this with some ALU-FOIL or something, and start looking for a new board.

[hasu]

Seems like 9 and 14 traces in your membrane sheet are broken.
Recently I repaired two model Ms with defective membrane sheets, both keyboards has defect on connector part of the sheet. Like this picture:


I used a nickel conductive pen from CircuitWorks to repair those and works well for me so far.
I think a defogger repair kit and a shielding paint for guitar cavity also work if length of repair path is short.
Conductive pen is expensive, also repair kit and paint are not so cheap so I think buying new sheet from Unicomp might be better option.

And also copper tape with conductive adhesive work though it is a bit difficult to connect it to membrane trace. I think Alu also is usable.

[ch_123]

Anyway, so this board (Lexmark btw) contunues to dissapoint me on a daily basis. If only I could get my hands on an US made Model M, they are kind of rare here in Europe.

Lexmark didn't make the European Model Ms, IBM did themselves. Although it's open to some debate as to how much IBM actually made, and how much came from Lexmark.

[mbc]

I can sell you a spare membrane plus controller for 10eur plus shipping