Hi, I have a double board Galaga PCB and have owned it for over 20 years with no issue. I believe it's an authentic however I can't find Midway or Namco etchings anywhere on it. The ROMS and such have stickers and numbers.
Recently, the unit will not boot up - right around the time of the explosion sound on boot up there's a pop noise and then it continually reboots.
I've taken the board out and reflowed the solder over 200 different things and have focused around the section where the custom explosion sound chip is. I've also recapped the board with new electrolytic caps. Board is in excellent condition, no water or moisture damage, but just some typical corrosion on some of the pins that are visible. I've used deoxit on all removable chips and wiggled them around.
No change in performance, power supply is strong and normal at 12 and 5 V, and I've even hotwired it with an auxiliary power supply and it has the same issue. It's being powered from a DC power supply so there's no AC conversion needed.
Really stumped as to what the issue is perhaps it's the custom explosion sound chip or something else.
Diodes and transistors all check good. Checked continuity on every chip I could find and nothing seems to be dead shorted throughout meaning I don't think there are any totally bad chips, but I don't have a definitive way to test.
Swapped the 3 Z 80s around and no change.
Here's a YouTube short, which contains the issue, I'd appreciate any advice you may have.