Seeking help on rebooting Galaga PCB - see video

davismv

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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.

 
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make sure the Freeze dipswitch (in yellow) is not turned on. this is probably your problem because the self test is saying RAM OK ROM OK, and the Freeze dipswitch makes it bootloop like this. I have a couple Galagas that do this too and I think I tried changing the Freeze dipswitch with no improvement. I'm certain there's a resistor pack off the dipswitch bank and if you have the ones that look like flat green wafers those are extremely prone to just breaking. I haven't done Galaga experiments in a very long time, so obligatory YMMV lol

galaga.png
 
Thank you so much for the reply. It means a lot to be getting information from the community here!

I just checked and freeze is off and all my dip switches actually match your configuration in the picture so we must like our bonus fighters the same way!!

That said, I did check the dip switch by moving in a couple times looked at the resistor pack and it's solid next to it with no issue.

Same thing persists.

Also, I removed the custom chip, which I believe contains the "boom" audio, and now there's no pop or noise, but it's still continually rebooting.

I've also found out that this board appears to be a clone.
 
Did that too it's right now it's about 5.1, I even brought a little higher to maybe 5.3 with no change.
 
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