I turned Nintendo Famicom into a stereo, and listened to the music

2 audio outputs, AUX A and AUX B, are output from the Nintendo Famicom CPU.Typically, the outputs on these pins are mixed by resistors to produce a mono audio signal.

It is not a formal stereo sound, but separating them makes it look like stereo.In the comment of the article I wrote before, "gokichan" recommended this way, so I tried it.

　2 audio outputs

Pin 1 of the CPU of the Famicom is AUX A and pin 2 is AUX B.

The AUX A has a 2 channel rectangular wave sound source connected to it, and produces a mechanical sound characteristic of Nintendo Famicom.

The AUX B is connected to 3 types of sound sources : triangular wave, noise, and ADPCM. The AUX B mainly produces bass sounds and drum sounds.

Typically, these outputs are mixed by resistors to produce mono audio.

　Channel separation

Cut the cable before the mixing resistor that leads to each audio output.

Add a 47 uF capacitor to the cable connected here to produce an audio output.
This is all.

　Modification

The photo arrows are the third and fourth from the left of the resistor in the lower left of the board when the slot of the cassette is facing up.

Cut these feet or use solder to remove them.

Pull the shield wire from the photo arrow on the back of the board.

Connect a 47 uF electrolytic capacitor to the end of this shield wire.

I installed the audio connector there.

The shield wire is recommended to be thin and flexible so that it can be easily wired in narrow places.

　 Listen

Let's listen to the sound of SUPER MARIO BROS. 3.

I just assigned different sound sources to the left and right channels, so it's not stereo, but it feels like stereo.

If you mix AUX A to” left 1 : right 2” and AUX B to” left 2 : right 1 ”,without dividing them into left and right, it will look like stereo.

It is quite interesting.
I want to listen to the sound of other games later.

2019.1.15 Postscript

I listened to other games.

I listened to "Mother" and "ICE CLIMBER" on the Nintendo Famicom.

We are now selling a modified kit for high image quality and natural pseudo stereo sandwich with video output.
You can enjoy powerful Famicom on ordinary TV.

ebay.com