deskthority

Dear folks,

I recently found a white alps KB (seems to be wiki/NTC_KB-6251 or maybe wiki/Chicony_KB-5161), including a switch for A,S or X at the bottom.

https://imgur.com/a/ACRW9P1

The a-key and the c-key were not working, therefore I replaced them using white dampened alps switches from an old Apple AEK II and solderd them onto the PCB.

Unfortunately after reassembling the keyboard, it seems that no key is working anymore. Still, the LEDs get activated, after pressing CAPS, NUM or SCRL.

Is there anything, I can do, to rescue this board?

Many many thanks

Thomas

After completely reassembling it, it seems to be working now. even a and c key.

Topic can be closed now.

Need to open again. After cleaning the whole keyboard and replacing all switches, two switches cause the according key to be sent plus the adjacend. I thought that my soldering was not too bad. May this be caused, by compressed air I was using also on the pcb?
Any thoughts how I can overcome this issue?

Many thanks!
Thomas

Can't help you with the issue, but the keyboard seems to me like the Monterey K104:
wiki/Monterey_K104

Thanks Jan for your clarification. You were absolutely right!

Is there any option apart from handwiring, of how to replace a faulty PCB/circuit board?

What exactly is bad on your PC board that needs replacing? Anything visible should be repairable. I have a junk K104 PC board with many lifted pads from a botched desoldering job (not by me...) if that would help.

thanks for your reply.

I'm a bit stumped tbh. If I press "n" I get ",n" or "n,", if I press ",", I get the same result. E.g. for "6", I get "678". Still, most of the other keys work well. So it seems to me, that something must be faulty on the circuit board, but there's nothing visible to me and solerdering does not seem to be to bad.

Any clues?

Mechanical failure on the switches' end would not produce such an error. I'd recommend checking things out with a multimeter on the affected PCB contacts. You could also try desoldering the keys that have issues and see whether the problem persists when bridging the contacts manually.
Another possibility is a failing controller, but that's unlikely.

tko2007 wrote: ↑

11 Aug 2021, 11:18

thanks for your reply.

I'm a bit stumped tbh. If I press "n" I get ",n" or "n,", if I press ",", I get the same result. E.g. for "6", I get "678". Still, most of the other keys work well. So it seems to me, that something must be faulty on the circuit board, but there's nothing visible to me and solerdering does not seem to be to bad.

Any clues?

You said you cleaned the board, but any chance there's some sort of dirt or contamination? Maybe something spilled on the top side that got down between the plate and PC board? Just a wild guess...