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Please Help! Trying to fix Keyboard PCB

Posted: 17 Jul 2019, 02:19
by Draxion
So basically I took apart my ducky one 2 to lube my switches. I expected something to go wrong as it's my first time doing this. I've lubed a soldering all the switches back onto the keyboard however as expected some don't work. I've fixed some that didn't work using a bridge, however these, 6, 7, Y, U, H, J, N and M don't work and I can't find which connections to bridge. Help and input would be great, Thanks for the help in advance!
IMG_20190713_182923__01.jpg (261.43 KiB) Viewed 1627 times

Re: Please Help! Trying to fix Keyboard PCB

Posted: 19 Jul 2019, 08:25
by DMA
Definitely something with a column - or may be two. I see you have 3 greenwires (even if they're blue - they're still greenwires). Are you sure they're correctly soldered? If they are - get your voltmeter out and measure voltages on both terminals of a key that works (pressed AND released) and then on the ones that don't.
You should see +5V and 0V (relative to ground, which is usually black wire from the cable, but the bolts are usually ground too) on the working one - but it can be +5V when pressed, or +5V when released. Note the direction of current, too - i.e. what terminal is +5 when released.

On the ones that don't - several scenarios possible.
1) 0V. You have a crack in one of the traces. You'll need a magnifying glass.
1a) it may also be that you fried a MCU pin. But those are quite tolerant nowadays, should withstand several minutes of being shorted to the ground.
2) +5V. Same - or may be something shorted to +5V rail. Which is extremely rare, power rails are usually away from matrix.
3) +0.6V. There's a solder bridge between this trace and the ground. Patience and magnifying glass help with that.

Good luck! :)