Technos Renegade arcade PCB repair
Renegade is a JAMMA pcb and the predecessor to Double Dragon. Initially it seemed the vertical sync was broken on this board – the image rolled vertically very fast. I traced the sync line from the JAMMA connector back on the top board and found it goes to the bottom (video) board. After cleaning up a lot of dirt and dust, a massive gouge in the bottom board became clear! Must have been a fairly heavy impact as you can see two TTL pins are sheared clean off.
Bridged the broken traces with wire and sync was restored but the image was cut into three pieces.
Re-checked the repair with a logic probe and found no activity on one of the repaired traces. There was actually a through-hole to the other side of the pcb in the damaged area that need soldered back on the trace. Then everything worked 100%.