deskthority

Hi makers! On my recent build I have some keys "jittering", to be more specific only those keys in row6 and row7. I replaced all diodes in these rows by new ones which unfortunately didn't solve it. Does someone have a clue what could be the issue here? Here I'm trying to visualize my problem:

It does not look like a diode problem. It looks like you have a intermittent short between row6 and row7 wires. Or a fixed resistance between those wires is not infinite but around the pull(up/down) resistor resistance.

vvp! Alright, I checked the pins of the Atmega with a microscope but couldn't see any suspicious solder lumps which could create a bridge. However, I took my soldering iron and reflowed the solder joints anyway. God in heaven, that solved it! The lesson I learned is, that I can't even trust my 300x microscope, since lumps may hide between the pins at spots and angles where my magnifiers/microsopce can't see. My alternate theory is, that I forgot cleaning with Isopropyl (yes, I did), and little solder paste balls created a semi-bridge between the pins? Can that be? Anyway, keyboard hail!

Isopropyl would be good for excess flux, not so much for bridging. I haven't done much surface mount yet, but one trick I'd suggest is using soldering wick on top of the contacts to remove excess solder and potential bridges.

If it was SMD then it could be some soldering paste which was not melted and created a (high resistance) connection between the two pins. Or it could be other things. Hard to tell without detailed pictures. And even with the pictures we just may not know.

Ah alright... now. Marked the thread as [solved]