SNES Repair Attempts - How'd you go for troubleshooting?

Hi everyone,

I recently got two non working SNESes and one NES control decks from the local flea market for a very cheap amount. I'm started troubleshooting the first SNES, but honestly i'm a bit stuck... Hoping anyone of you could shed some light.

Observed symptoms:
- The unit do powers on.
- NO video and no sound, just a black screen. Cleaned the cartridge connector and the mother board thoroughly and still no luck. Also cleaned my cartridges, no luck either.
- I noticed that the screen "jumps" as you'd expect when I turn the power on / off, so some kind of signal makes it to the video output I guess. The reset button also produces the same effect (similar effect as when the cartridge is dirty and can't boot).
- Carefully inspected the motherboard looking for broken traces, corrosion or any visible damage on the boards / chips: found some oxidization under one of the sides of the cart connector, just where the screw that holds it goes. Cleaned it, inspected again for more damage, nothing else was found (still no luck).
- No signs of leaked electrolytic caps.

In your experience, what should I look at next. What can I test without a logic analyzer / oscilloscope in the hopes to repair this unit. I guess replacing the SRAMs and/or all electrolytic caps and keep my fingers crossed could be an option :S.

Thanks a lot in advance.

The S-CPU seems to be overwhelmingly likely the device that fails in a dead SNES, and it's unfortunately not particularly repairable. ( viewtopic.php?p=157511#p157511 )

DogP's page has some good information: http://projectvb.com/nss/logs.htm

Thanks a lot guys. Those are certainly useful pieces of information .

Too bad that the only way to get those S-CPUs and PPUs is by scavenging them from another console .

I'll check and report back.

Thanks again!

To reiterate what dogp observed: A lot of games explicitly wait forever for the APU to get ready before they'll boot, so if you have a socketed APU, you could try re-seating it.

At least "loose APU" is the easier failure mode to repair...

That would be definitely worth a try. Unfortunately this unit's APU come as soldered chips in the mobo (not socketed nor removable).

I'll give it a closer look later, under magnifying glass. Maybe cold solder in the SOICs or QFPs can be the cause, and if so, reflowing the chips can help, I guess.

Thanks again guys.

Ugh... Just learned that the S-WRAM chip is a Nintendo-custom DRAM chip (with 3 /CS pins, system clock input and some other different things...), which means that one cannot replace it with an off-the-shelf component. I guess this makes things worse since It seems that my unit's failure rest either in the S-CPU or the S-WRAM...

Well, I'll try to source broken units for parts as my last resort (just for learning / pride sake XD).

Any thoughts on this?

Thanks!