Double Dragon 3 Repair Logs
Symptom: Dead/missing parts
IC 79, one of the pair of system ROMs was missing. Burned a replacement EPROM and installed it but board would not boot. Inspected the bottom of the board closely as it looked like it had been badly abused. Fixed 3 shorts (pins from a chip laying over shorting a trace) on the bottom of the board and patched 8 cut traces. Board booted but had no sound. Installed a missing YM3012 Sound DAC (Pulled from a parts board) but still no sound. A closer inspection showed the Z80 CPU had NO activity on its address and data busses. No logic highs, no lows, just dead. Replaced the Z80 and had the same symptoms. Checked the reset line and it was cycling from low to high but doing it incredibly fast. Traced the reset circuit back and found legs in the board but no capacitor in the circuit. Replaced 1 cap in the reset circuit and played the game through to the end.