Help With Famicom A/V Mod

[Ze_ro]

So, I bought a Famicom off eBay, and even though the seller never mentioned it, it turns out it's already been AV modded. It has a standard 8-pin DIN port on the side that looked suspiciously like a Genesis video port, but I didn't get a cable with the system, and I was hesitant to just hook stuff up without knowing for sure, so I decided to open the system up:



Well, the yellow wire is clearly composite video... but I'm a little confused with the red and blue wires. Searching the web for AV mods is easy enough, but for whatever reason, none of the pictures ever seem to show where audio is getting hooked into.... and as far as I know, the Famicom doesn't do stereo. Can anyone enlighten me as to what's going on here?

At any rate, RF works fine for me, and I actually get fairly good reception on channel 95... but since the port is already there, it would be nice to make use of it.

--Zero

[133MHz]

The red and blue wires are going to pins 1 and 2 of the CPU, so yeah they're actually pseudo-stereo audio. It works fairly well but keep in mind that you won't get enhanced cartridge sound from the AV out unless you rewire it to use the standard mono audio output.

[133MHz]

Not in Japan. That DIN plug was used in many consoles and home computers of the time as an AV output, like the MSX computers, the PC Engine, Mega Drive and some others I can't quite recall right now. Makes sense to use it if the cables are readily available.

[b1aCkDeA7h]

Hey, if it can do A/V off of a generic and easy to find cable, I would be all over that.

My mod looks like a trainwreck but it works.

If you need a model 1 mono Genny cable, I think I have one.

[Ze_ro]

keep in mind that you won't get enhanced cartridge sound from the AV out unless you rewire it to use the standard mono audio output.

Where would that output be?

--Zero

[b1aCkDeA7h]

Take a picture of the whole board and RF unit and we should be able to help you out and point you to the right place.

Theoretically, it should be just moving the audio wire to a different pin. Don't quote me on that though.

[Ze_ro]

Is this good enough of a pic, or do you need to see the top of the PCB? The AV mod is a little delicate, so I don't want to move the board any more than I have to.



(Yeah, I'm a little slow with this... it wasn't until I got an FDS that sound issues got noticable, and I didn't have a lot of free time until recently).

--Zero

[ericj]

If you want, you can put some hot glue over the connections on the PCB to make it more secure. The arms on transistors have a tendency to snap off pretty easily.

[NintendoKing]

^
Incredible, from this angle the mod looks almost like something standard to the system. Its very well done.

[133MHz]

Desolder the red and blue wires from the CPU pins, join them together and solder them to the point marked as SOU.

[Ze_ro]

Awesome! It's working great now, thanks a lot!

--Zero