Before it arrived I ordered a new z80, thinking it would be just a matter of replacing it.
First thing I tried was putting the Uni BIOS from my 4-slot in. The Uni Bios allows some errors including the z80 to be ignored and further troubleshoot the board.
Sure enough games would load but with no sound and lines through sprites.
The board was nice and clean with no obvious signs of damage.
From RJ's repairlogs:
http://www.arcadecomponents.com/index.html"channelmaniac wrote:Error could be caused by the Z80, Sound ROM, 6116 SRAM IC, NEO-257 IC, NEO-G0 IC, or they YM2610 sound IC. Basically any problem that causes the sound system to appear unresponsive will give this error.
I probably should have read up a bit before I went ahead and ordered the chip, but never mind.
Broke out the magnifying glass, still couldn't find any damage. Flipped the board over and this time something caught my eye. The headers where the cartridge connector board joins the main motherboard had bent pins all over the place.
2 of the pins were shorted together, leading straight to the z80.
Straightened the pins using a click pencil threaded over the pins like this:
http://people.sinclair.edu/nickreeder/E ... ngTips.htm"
The board now booted with a normal bios back in but still with the graphical glitches. At this point I went ahead and checked continuity with a multimeter on every pin on these connector solder points.
I found one broken trace that was impossible to see by eye. So I dropped a quick patch lead of wire wrap over the trace and sure enough the board was restored to proper operation.
So I cut the rough patch and made a proper repair with Kynar.
I'll finish the repair when my Green Nail Varnish arrives which will seal the Kynar in place and look totally awesome on my toenails.
