Yeah, I was wondering what would happen if you ground out a column on the matrix. I didn't want to blow up my encoder. I was happy to use the +5V and ground off of the PS2 to go to the interface, then I went to hook up the "key presses" and went "uh oh", how come there aren't 8 connections, only 4.
I'll probably buy a comercial encoder and replace the keyboard, Hans splitter keyboard circuit (I can't believe I spent 8 hours building this), and a couple of custom optical hacks. I built the panel in 1998, so I guess it's due. I just was kind of liking what could be used "for free". Call it recycling.