Super Nintendo without sound

Last month I was checking out a pawn store and left with a "broken" NES and a few games. I after giving the NES a much needed cleaning (the outside was really grimy and there was soda all over the inside), I repositioned the connector pins and disabled the security chip. It worked perfectly fine. I went back to the shop a few days later to get some more games and I mentioned the the guy that I got the NES working. He reaches behind him and holds out a SNES and says that it worked when he got it but not anymore and that I could have it for $5. I felt so bad for the thing, it was as grimy and the NES and some stupid brat had drawn on it with a marker. I take it and and when I open it looks like the soda fiend has struck again. And an army of little water bugs crawled in to get at the soda and decided it was so nice and cozy in the system that they stayed til they all died. It was gross.
So the immediate issue I saw with the system was that the plastic inside of the power port was snapped off. I replace it and no power. I put in a new fuse and it powers on but nothing on screen. I give the cartridge slot a good cleaning (the crap that came out was blue-ish) and the system plays! But there is no sound. Now I'm stumped as to what to do now. This system has board revision SNS-CPU-GPN-02. I'm not having any other issues with it other than the lack of sound. I played a few levels of Super Mario World, Donkey Kong Country, and StarFox and there weren't any graphical hiccups.

 

Start with the most simple and work your way up.

-Does another SNES works sound with the Same AV cable on the Same TV.
-Test with both AV out and RF adapter.
-IF still nothing check continuity of audio trace from output to source and see if something is broken.
-Replace capacitors.

 

-My AV cable is working fine, I tested with my own SNES on the same TV.
-I tried it with an RF cable and still no sound.

I have most of the capacitors needed to replace the old ones with the exception of the two 33uF 25V near the voltage regulator. Does it make any difference whether or not I use audio grade caps?

Edit: Herp derp, forgot to ask which traces to test.

 

Using audio caps should not be a problem, as long as you respect the values. Those should be for filtering the power rail.

You may want to just recap the thing, no sound is a common cap related issue, and IIRC the SNES does not have too many of them.

As for which trace to test, just follow the audio pathway, I have no picture for you.
If you need a schematic for the SNES there is one on NESDEV forum. It is for an earlier version of the console but many things are similiar.
It might be a good idea to check the traces, especially since you said there was liquid in the console, might be there some corrosion.

Beyond that might be a defective chip... Or a problem with the mute function. ( Could be a broken trace again )

 

I haven't found any broken traces yet but I pulled off the connector to have a look and there is definitely some corrosion on a few pins. And some more soda.

 

My Super Famicom (1990 original release unit) had bad caps and corroded traces. I replaced the caps (was really easy) and the unit was back to it's former glory in less than an hour of work poured in.

 

I replaced some caps but no luck. It looks like some traces leading to the sound chip are corroded. I'll post a picture when I get off work.

 

Mine had corroded traces too. Mending them being required for successful repair don't even need to be mentioned, right ?

 

I think I've got it figured out. I tested the some of the corroded traces that connect to the S-SMP chip and they seemed fine. I noticed a trace that connected to the S-DSP chip that looked pretty bad. I checked and no continuity. I looked up the schematic and it connects to the audio amplifier circuit. Now I need to try fixing it. What would be the best way to repair it? The cartridge slot sits right on top of the spot.

 

I would just solder a thin wire between the two ends of the the trace.
If the trace is big enough you can scratch to reveal copper and solder on the trace.

 

Alright, I soldered a bit of wire from the through hole and to the DSP chip. I popped in StarFox, hooked up the power and AC adapter, turned on the system...



I CAN HEAR IT! THE SOUND WORKS AGAIN!

That one little break was the problem. This system is fully functional once again. I'm gonna clean up the rest of the corrosion first before I try to sell it. Hopefully it will go to someone that will take care of it and not spill soda all over it.

 

Good job, congrats on your repair dude. Way to go

 

Thanks for the assistance. I'm really proud of getting this system working again, I think it was a good learning project. The SNES is one of my favorite consoles so I'm really happy to save one from getting stripped for parts or, worse, getting thrown out.