Ms. Pacman/Galaga reunion PCB issues - missing starfield on Galaga

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Ms. Pacman/Galaga reunion PCB issues - missing starfield on Galaga

Hey guys,

I recently purchased a Ms. Pacman/Galaga 20 Year Reunion (Class of 1981) original cocktail arcade cabinet. Everything works great except Galaga and the main game selection screen are missing the starfield. Instead you just get a black screen in the background while playing Galaga. When the board boots up it display no errors and all ROM checks are good. Gameplay is perfectly fine and there are no graphic glitches except for the missing starfield.

I went ahead and purchased a used PCB on Ebay, swapped it out, and now everything is great. I took the 2 chips (U13, U14) off the defective PCB, placed them in the new board, and everything still worked just fine. I then took the 2 chips off the new board and placed them in the old board, booted it up, and it's still missing the starfield. Obviously all the chips are good and there's something wrong with the PCB itself.

Based on research I've done on this site and in general, it seems that sometimes the Galaga PCB needs more power. I've tried adjusting the power on my power supply, and my multimeter read 4.85v originally, and I adjusted it up to 5.3v...no difference, so power doesn't seem to be an issue here.

Anybody have any idea what could be wrong with the board? I haven't had much luck finding troubleshooting information on these reunion boards, mostly the original individual boards. Any ideas would be greatly appreciated.

Thanks.
 
No. It's completely missing. Screenshots attached.

Thanks.
 

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Aren't the reunion boards emulation ?

If Galaga was like Galaxian there was a hardware circuit to make the starfield and there was a signal to turn it on/off.... if the reunion boards are emulation, there may be a setting somewhere to turn the starfield on/off.

Just a guess mind you as I don't have one of these (yet ? :) ).
 
I don't think the reunion boards are "emulation"... I'm pretty sure it's just new code. AFAIK, the code runs on a Zilog Z180, and the majority of the rest of the circuitry is in the two large CPLDs (usually with the heatsinks on top).

I'd guess that the starfield is generated by one of those CPLDs. Seems strange that just the starfield circuit would fail in the CPLD... but it could be missing a signal that it needs to run. I'd use a magnifier and inspect the pins of the CPLDs and see if any of them look to be lifted, damaged, etc.

Chances are ... its the ceramic capacitors . Im on the same boat. I cant find anyone to fix it.
Just curious... why do you think it's ceramic capacitors causing that problem? I haven't really been following reunion PCB repairs... is that a common solution or something?

DogP
 
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Thanks, guys. You've given me some good direction.

I briefly inspected the board before work this morning. All the pins of the CPLDs appear to be intact. If what I'm looking at is what Neilhdz mentioned as being a ceramic capacitor, then I found one (C3, near the JAMMA connector) that appears to have one side lifted up off the pad. I'll try soldering it after I get home from work today and I'll post my results.
 
Just curious... why do you think it's ceramic capacitors causing that problem? I haven't really been following reunion PCB repairs... is that a common solution or something?

DogP


I've purchased enough of these boards in bulk to compare the ceramic capacitors. Theres nothing else to repair on those boards except that. Sucks i dont have the tools if not i'd be repairing these boards.
 
although I don't have the web link handy, I read a resource that stated the Namco reunion and anniv pcbs are not emulation. the pac party which contains a handful of games is, though.
 
I've purchased enough of these boards in bulk to compare the ceramic capacitors. Theres nothing else to repair on those boards except that. Sucks i dont have the tools if not i'd be repairing these boards.
Huh? There are plenty of parts on these boards that can go bad besides ceramic capacitors (CPU, CPLDs, RAMs, ROMs, video output circuit, etc).

Generally, the ceramic capacitors are simply bypass caps placed next to each IC, and while not recommended, a board would work just fine without them.

DogP
 
Well, no such luck. I did a quick soldering hackjob to fix C3, but the behavior hasn't changed. Everything still works fine, but the entire starfield is missing. I inspected the area pretty thoroughly and verified that I didn't accidentally bridge the 2 sides of the capacitor. I was also able to fully trace one side back to the individual pin on one of the CPLDs, and the other side to ground. C3, while not pretty, is definitely re-attached. However, the problem remains. I checked for any obvious damage across the board and came up empty.

Any other thoughts/ideas?
 
Well, no such luck. I did a quick soldering hackjob to fix C3, but the behavior hasn't changed. Everything still works fine, but the entire starfield is missing. I inspected the area pretty thoroughly and verified that I didn't accidentally bridge the 2 sides of the capacitor. I was also able to fully trace one side back to the individual pin on one of the CPLDs, and the other side to ground. C3, while not pretty, is definitely re-attached. However, the problem remains. I checked for any obvious damage across the board and came up empty.

Any other thoughts/ideas?
Sorry for the necromancy, but did you ever learn more on this?
 
I never found anymore on this when I looked but I have the same problem. I check both roms and both checked out so the problem is not on my roms. I just don't know what component is responsible for the starfield.
 
No updates from me either. If anyone has any other ideas I am willing to take a closer look, but I'm just not motivated since I replaced this with a fully working board.
 
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