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geekhack Community => Keyboards => Topic started by: monotux on Sun, 20 November 2022, 15:19:13

Title: Three keys dead, how to fix?
Post by: monotux on Sun, 20 November 2022, 15:19:13

I recently assembled my first board in years (hello family commitments!) and it seems three of the switchtes aren't registering.

My troubleshooting this far:

• I tested all three switches with a multimeter, and I got a beep from the continuity mode when pressing down the switch. I think that means that the switch is OK, and that the soldering is OK.
• I then resoldered each switch to make sure it was fine, continuity tested OK but still no keypress registered
• I then unsoldered one switch and tested it, passed the continuity test
• I then tested the PCB holes for the switch with the same continuity tester, and nothing. Nothing registered.

So I guess that the switches are fine, but that the socket or the PCB is broken. How do I fix it?

https://imgur.com/a/lf66Zb2

The picture shows (with too little depth of field, sorry...) the three switches having issues.

Title: Re: Three keys dead, how to fix?
Post by: suicidal_orange on Sun, 27 November 2022, 04:55:52

Sorry, somehow missed your post!  A better pic would be good but lets have a go anyway.

From what I can see it looks like you've damaged a lot of the half-pads that should be linked to the diodes - the red, pink and blue dot pairs should have continuity, if they don't you'll need to solder a jumper wire from the switch pin to the end of the diode.  Why the diodes are so small I don't know, that will make it harder :(

That might fix it but if not the XD75 is a community DIY PCB which means it's sane so there should be continuity running up the columns, like the yellow and green dots.  If there isn't you'll need to solder jumpers to reconnect them.

[attach=1]

Title: Re: Three keys dead, how to fix?
Post by: monotux on Wed, 06 December 2023, 02:53:53

Thank you very much for your reply! It helped me figure out and fix the issue. And sorry for taking more than a year to reply :)

Turned out that the columns was the issue in this case. I just soldered some jumper wires between them and it solved the issue.

Not the prettiest solder job but it was Good Enough (tm):

https://imgur.com/a/t0F4wCA

Edit: not sure if the imgur link will work forever, attaching the same image to this post as well: