Troubleshooting a malfunctioning PCB

[Mindspider]

Hello all,

The top row of my keyboard recently started malfunctioning, and I could use some help troubleshooting. Each key is activating the column of keys below: ESC also activates Tab/Caps/Shift/Ctrl, 1 also activates QAZ, 2 activates WSX, etc. My PCB is a DZ60RGB-ANSI v1 hotswap from KBDfans. No known cause of damage: no drops, no spills, haven't moved the keyboard recently.

I took apart the board and did not find any obvious damage, poor soldering joints, etc. I also tried flashing the board several times, which did not fix the issue. Any suggestions?

[suicidal_orange]

My head isn't clear enough to work this out but what happens if you press other keys at the same time, say 2 and T?  If it's diodes I think you would get an extra key registering (5 or W) if a short ... not?

Neither make much sense assuming the board lives in a case as the chances of a whole row of diodes dying while the rest of the board are fine must be really slim, and shorts don't usually happen randomly either.

[Mindspider]

Good question. I just tried it out, and I didn't get any extra keys registering. Is there a way to identify and report a short on a PCB like this, or should I plan to replace the board?

[suicidal_orange]

To test for shorts you need a continuity tester or multimeter in diode test or continuity mode (so it beeps when the probes touch) The diodes connect down the columns on the left pins looking at the back of the board so there should be no continuity between rows on the right switch pins.  A short between the right pins on the top row and an LED could also cause this, but unless you added LEDs it's another unlikely option.    If you have a tester you can also test the diodes - they should beep with the probes one way round but not the other, if they beep both ways they are dead.

If it's in a metal case you could have given it a static shock and killed the controller pin for the top row making it constantly live, that may well do the same thing.

I'm sure it should be fixable but I'm medically retarded at the moment and incapable of thinking things through so I'm not much help

Also I think there are two versions of the DZ60, if this happened after flashing the firmware double check you're using the right revision.  I should know what the changes are as I've fixed a few of these but again, brain = mush.