Need help troubleshooting odd issue

Learning and discussion Custom keyboards
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So quick intro I have a KBD75 board that has been running perfectly fine for the last 2 years. Recently my power went out and came back as you’d expect from a tropical storm hitting your area, not sure if it matters but this issue started after my power came back.

Anyway it turns out SOME keys such as q,w,e,r,t,y,u,c,v,b don’t work while others obviously do. The LEDs on the build are working fine for all keys. I’m not too educated on shorting issues, or really any possible issue that may be causing this so I’m looking to you guys for help or any ideas on how to fix this.

Just wanted to inquire with you guys in case this can be fixed on my end before sending it out for repair.

Thanks

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I’m not an expert, but it sounds like your board may have possibly been hit with a surge. If you’re comfortable doing so, I might try taking the keeb apart and looking closely at the PCB, looking for any damaged components or traces. Some things can be fixed / replaced, others would require a new PCB.

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Thanks for replying. I’m about to take this thing apart, what should I look for in terms of any signs/traces of damage? Would there be burns or something? Might sound stupid but I don’t know what surge damage looks like on a PCB.

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You’ll be looking for anything that is burnt basically. When a power surge hits it’ll blow components & burn traces. So anything that is discolored is suspect.

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As said others you should look for anything visually strange on your pcb first hand.

Your MCU looks to be not completely dead:

  • only a few keys not working.

Things to check:

  • if I O P and other keys on the same row as Q W E R T Y U keys are working.
  • same for Z X and other keys on the same row as C V B keys.

If they are not then maybe some MCU IO pins took the surge.

Then check diodes, either visually (not the most reliable, some components can be damaged without anything visible) and better with a multimeter.

Good luck!

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Though I do suspect component damage, have you tried unplugging it, and leaving it unplugged for a few minutes?

I have seen electronics, do weird things, in my IT tenure, most of which get chalked up to static build up.

Also, I’d highly recommend investing in a UPS. I’ve seen electronics die, from power flickering on and off. Low power scenarios AKA brownouts, can be just as bad, if not worse, then a surge, as a surge protectors can’t compensate for them, where as a UPS, will kick over to battery power, when the voltage drops below a predetermined amount.

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