Help fixing a non-working key

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SwissArmyTin

08 Jul 2018, 01:42

Today I was finally putting the final touches to my first project board, got the new switches swapped in, new keycaps on, aaaaaaaaaaaaaaaaaaand one of the keys doesn't work.

I've tried swapping the switch with spares 3 times, cleaning the PCB of any stray flux, the pads look fine, the solder joints look fine, no noticeable broken traces, and it worked before I swapped the switches. This is my first time working on something like this, and to be honest I'm completely baffled.

Any help?

Edit: forgot to add some details that would help. PCB is a generic tenkeyless, double-sided, has diodes and SMD LEDs, and switches are Box Jades. All the diodes are fine, all but one of the LEDs are ok. The bad LED is under the Escape key, while the key I'm having problems with is the Enter key. Hope this helps.

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Sangdrax

08 Jul 2018, 04:10

My bet is the diode is in backwards. That would give you that behavior. Might be the same problem with your LED too. If not, did you use a multimeter in continuity mode to check traces instead of just your Mk I's?

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SwissArmyTin

08 Jul 2018, 04:33

Sangdrax wrote: My bet is the diode is in backwards. That would give you that behavior. Might be the same problem with your LED too. If not, did you use a multimeter in continuity mode to check traces instead of just your Mk I's?
Both the diode and LED check out as far as I can tell, I'll try testing for continuity again tomorrow. I'll be doing it essentially blind since for some reason there's no traces leading to/from that switch on the underside of the PCB.

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SwissArmyTin

08 Jul 2018, 17:16

Well, poking and prodding around with my multimeter and I discovered there's no continuity between one of the top pads and the bottom pads. Digging through a pile of the original switches, it seems I accidentally ripped the copper out that connected the two pads -_-

Guess I'll have to run a jumper at some point...for now, I've just remapped the \ key to act as a temporary enter, so I can get some use out of it for now.

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