4RFV Row Not Working

[Kraligor]

Hey all,

got a cheapo Chinese keyboard on eBay for $10. Turns out the 4RFV row isn't working. It's definitively a keyboard issue, cross-checked with different computers. Any tips on how to resolve it?

Here are pics of the PCB, closeup of controller and affected row. I couldn't spot any faulty joints, but then, I'm not the most experienced spotter. Maybe C16 on the controller? Sorry for the bad quality, didn't have my other phone at hand.






Thanks in advance!

[tp4tissue]

It's unlikely for us to see cracks from these photos.

just follow the line that connects all these switches..


and short it manually down the line, until you find where the break is..

[TalkingTree]

just follow the line that connects all these switches..

and short it manually down the line, until you find where the break is..

Better yet, test continuity with a multimeter.

[Kraligor]

Thanks, will do. Always from the opposite switch pin to the next contact in the trace, yes?

[TalkingTree]

Always from the opposite switch pin to the next contact in the trace, yes?

Bear in mind that diodes are polarized and they will only allow the current flow in one direction. When in doubt, invert leads and test again.

[SamirD]

You can try the continuity test to find the exact break.  Or you could shortcut everything by baking the circuit board and seeing if that restores it.  I recently found out about this 'miracle fix-all' that apparently works very well on fixing equipment boards like gpus that stop working or have issues after a while.