SNES Mainboard Repair No Sound [Serial: UP17388130]

Ah! What do you know! Teach us Master!

 

It's not an op-amp. Why would Nintendo go to the trouble of having one custom printed? It just makes expense.

 

Any ideas on what it could be or a suitable replacement then?
Maybe you've got a spare S-MIX chip you're keen to post to the other side of the world! :victorious:

 

I have no bloody clue - it's been bugging me, too! lol. I guess from the MIX part it could be some sort of mixer. I haven't really studied one in a long time.

Somewhere I have a SNES missing parts, but I doubt I'll come across it for a long time!

 

NECRO THREAD TIME

I am currently trying to fix a SNES mini that has noise in the right channel, but not the left. The sound still outputs but it has what sounds like analog tv static on top of it. Quite annoying. It happens as soon as you power the snes, whether there is a game in the machine or not.
I ruled out the cabling, AC adapter, recapped the whole machine, still no magic.

So I got interested in that S-MIX chip. I tried reflowing it, no change.
But then, while the console was running, I applied a freezing liquid drop on the s-mix and it and it immediately made the static worse, it then came back to normal as the freezing evaporated and the temperature comes back up.

This seems like pretty strong evidence that the static originates from the s-mix. This chip is likely a mixer and amplifier all in one. Unfortunately a replacement chip wont be easy to find.

 

There's the 8 pin NEC chip near it. That's the D/A converter. Try the freeze spray on the 8 pin chip too.

The APU chip talks to the DAC through a I2S link (3 wires) and if the transmission link is faulty (there's three signals: clock, data and left/right clock) you can have such a problem where you have mono sound on one side and static on the other side.

The serial data (which is digital)on the data line would sound exactly like modem noise or analog tv static if it's forwarded to the analog side of the circuit due to a malfunction...

 

Yep, you are right there is a NEC 6379A D/A Converter right next to it. I tried the freeze spray on it but it did not change anything.

Btw I get stereo sound. Both channel have the actual audio. But the right channel has the static on top of it. This seems to point toward a problem that is downstream from the D/A conversion stage. Maybe I could try lifting the R channel input pin of the s-mix and ground it. If the noise is still there then the problem would be the S-mix or after.

But not sure it is worth the trouble, I might just put this console back in the pile until I find a donor board for a s-mix.