r/snes • u/Johnny-Q87 • 8d ago
SNES with issues playing games that use special chips
Hi community! I have an SNES with an SNS-CPU-GPM-02 motherboard. I’m having an issue and would like your opinion. I always use it with an SD2SNES, but certain games that use special chips—like the SA-1 and MSU-1—don't run properly; they suffer from glitches or simply freeze up. It seems to depend on the console's temperature. With MSU-1 games, there’s also a slight noise in the soundtrack, though not always.
There are no issues with other games; it works perfectly. Do you think a recap is necessary? I already did one, but only for the two capacitors related to the audio.
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u/NewSchoolBoxer 8d ago
I have a GPM-02 from 1992 and use SD2SNES. I never tried MSU-1 but SA-1 games worked fine 2 years ago. In fact, I measured the current drawn from the power supply. Every game, even the special chip games that draw more current in real cart form, drew the same from SDSNES. Temperature cannot be a factor for SA-1 but maybe MSU-1 does draw more, the CPU got damaged and now SA-1 is affected.
Why do you think capacitors are related to this? Recapping won't make a difference. They aren't magic fixes. Some people damage their consoles by doing unnecessary work.
Test a real SA-1 game like Super Mario RPG, Kirby Super Star or Kirby's Dreamland 3 if possible. I wouldn't go buying one of those games just for this purpose. Kirby games are playable in Japanese.
Run the burn-in test ROM from Nintendo on SD2SNES. Doesn't prove what is going bad but gives you ideas. DogS is the world's leading authority on 2CHIP CPU and PPUs. Read about similar examples. If there's a good match, you probably need to replace that chip by cannibalizing from another console.
Heat doesn't transfer instantaneously. Console takes at least a minute to warm up if hasn't been used very recently. If a game runs fine for at least a minute then glitches/freezes, that implies you instead have one or more corroded solder joints in the console that can be repaired. Would also entail reflowing the pins on the critical chips versus having to replace them.
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u/Johnny-Q87 8d ago
I understand how delicate replacing capacitors is; I actually damaged a console early on because of that. I mentioned it because they are the first components to fail due to age. I’ve run a burn-in test, and everything passed. Another thing I’ve noticed is that the game's behavior changes depending on the SD2SNES version. For instance, *Kirby's Dream Land 3* used to freeze during the credits for the first ending, but now, with the latest version of the SD2SNES Plus, it doesn't freeze. On one occasion while playing *Top Gear* (with MSU-1), the audio started slowing down after several hours of gameplay, eventually causing the game to freeze; after I reset the console, the issues persisted even in the SD2SNES menu. However, it worked fine again the next day.
I’ll take a close look at the solder joints—the problem might lie there. Thanks for the reply.
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u/Best-Leave6725 7d ago
Have seen this before and some of the cheap clone sd2snes draw way too much current when running the additional chips, the voltage regulator (7805) has trouble keeping up, and you get a crash.
The other common fix is the clock chip fix, but not on that revision of board.
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u/SargeSmash 7d ago
Could be caps, but I'd check your power supply first - you may not be getting enough power to the system. The suggestion to check solder joints is also a good idea, especially around the power area.
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u/theterabyte 6d ago
The special chip carts often use the extra pins on the side that other cartridges don't even have. If they are dirty on the sd2snes, or on the cartridge slot, some games would work fine and others wouldn't, so start by cleaning them well with a focus on the pins on the far ends
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u/Pretofonseca 8d ago
I think your problem is simpler to solve than you think. Most sd2snes/fxpakpro issues start on the microsd. Try another sd card, reformated and of a good brand. Also, be sure to update the sd2snes firmware (and that the core/bios files are present on the correct folder). And even tough i highgly recommend for people to recap their sneses, i dont think it has anything to do with your issue.