Help fixing an Ergodox matrix problem

[alisdair]

I'm having a problem with my Ergodox build that I don't know what to do about.

The first column of switches on the right board (SW5:7, 4:7, 2:7, and 0:7) all activate the entire corresponding row. For example, pressing SW5:7 also activates SW5:8, 5:9, 5:10, 5:11, 5:12, and 5:13.

I can't see how this can be happening. Looking at the circuit I can't imagine any fault with my build that would have caused this.

Does anyone have any ideas for what to do to fix this? What could be the cause?

Attached are a couple of pictures of the back of the board in case I'm missing something obvious:

[alisdair]

A quick update on this: pin B0 (the cathode on the column causing the problems) appears to have a short to ground. I can't find a circuit diagram for the Ergodox anywhere but given that this is only true for this column, I guess it's the source of the problem.

I can't see where B0 could be shorted to ground, though. Any suggestions?

[dorkvader]

I can't find a circuit diagram for the Ergodox anywhere but given that this is only true for this column, I guess it's the source of the problem.

here are the gerbers:
http://ergodox.org/Downloads.aspx

If you need screenshots I can just grab a gerber viewer and screenshot it.

Glad you got it looked at. I had a similar problem with a trace I didn't cut enough grounding to my metal case.

[alisdair]

FIXED. I am an idiot.

There was a bridge between the LED cathode and the diode cathode. I thought they were meant to be connected. Here's the culprit:



So, in summary:

* LED should not be connected to the diode
* If you have a key which causes the entire row to activate, you probably have a short on the cathode of the diodes in the column of the key

Time to enjoy my new keyboard