Repair a old Acer 6312 Azerty

[4sStylZ]

Hi people,

I discovered an old keyboard in a cellar. Before washing it, I tested the keyboard. Unfortunately many keys are not functional :

 - Enter.
 - Arrow keys.
 - All the bottom row.
 - Verr num.

I don’t know how too identify what’s the problem. The membrane does not seems damaged.
Any suggestion ?

Some pictures :

[tp4tissue]

follow the traces,  there could be a crack. or a worn out part..   or a cold joint pcb side.

[chyros]

Probably one or more of the traces has been oxidised. If any of the traces have black stuff on them, gently rub it off with a rubber.

[Daniel Beardsmore]

With one of mine, I had to peel the membranes off the PCB. It probably wasn't glued on (it would be hard to keep the glue from obstructing the connections), but whatever they had done, I've never got it to work properly since. The connection between the membranes and the PCB no longer seems to work well. Some keys still work, but most of them don't register and a few keys may type something odd.

Most membrane keyboards can be disassembled and reassembled safely, but the Acer didn't, nor did either of my AppleDesign Keyboards (one Apple, one NMB) that both typed complete nonsense afterwards. I never even tried to fix those.

[4sStylZ]

Thank you for your help.

I have followed the trace and, sometimes traces were oxyded under the membrane. In fact, I have tested the connection with multimeter and the black trace is still connected.
After that, I have rubbed and clean the pcb and all of the membrane key connect plot. They was completely oxyded.

The result : I have now the led who work but but the keys that do not work before still does not work. That’s a fail.

This keyboard is total imperfection. That’s a big fat piece of metal and durable plastique. Cable and connection are good parts. The switch aren’t the best but for a 23 year old keyboard they work perfectly and seems to bring good feedback but the membrane kill of that. 

Bad.

The only things I can use are the keycap.

[Daniel Beardsmore]

I don't think they're even nice to type on. The keycaps are OK — nice contrast but the printing method is a bit wobbly. I converted one of mine to linear and it even feels rubbish as a linear keyboard. The click leaves seem to work in Alps SKCM switches, but they don't click in Alps switches: they're tactile only.