Adding cap to sound on AV modded famicom

[fredJ]

First - please don't respond with "lolololol, need lubricating". You know who you are and if you can't make better responses than flames/insults please don't bother posting. You will be IGNORED. Thank you.

I have an AV modded famicom with cable out that has interference on the sound. I would like to add a cap to filter the interference, but not sure where to place the cap. Could it be placed on the wires? Or on the other side? What direction should I place it, and how big should the cap be (uF)?

Or could interference come from the ground (marked with yellow)?

I cut it up to remove the glue. Red goes to red (sound), and green to green (video). Yellow is ground.

The buzzing doesn't come from the microphone I know that much. It starts when the music in the game starts, so it is related to the power somehow.

[133MHz]

A capacitor in series or parallel with the audio line won't remove any interference, best case scenario it'll do nothing, worst case it'll degrade audio quality even further. Your problem could be caused by video crosstalk - try a game with little to no music and see if the interference changes with the picture content.

In case it is a power issue as you say then you'll need to replace the electrolytic capacitors on the voltage regulation stage, not randomly add capacitance here and there.

[fredJ]

Yes, the interference changes a little with picture contect.
Sometimes when I start up a game, there is no "buzzing". But the buzzing always starts when the gameplay starts.
But it depends. Sometimes the buzzing interference is there from the beginning too.

Do you have any suggestion what I can do about it?

[famifan]

TS deserves insulting 

you should start with proper shielding (sticky thread about AV mod) and dedicated separated audio mixing circuit

1 well lubricated cap can't resolve all the issues

[jpx72]

Use another shielded cable and solder it to the pad marked SOU (if you have the model with these solder pads), or directly to pin 46 of the cartridge connector
http://jpx72.detailne.sk/modd_files/fc/avmod/sound.png
Don't forget to connect the shielding to ground.

[80sFREAK]

1 well lubricated cap can't resolve all the issues

lubricated

And it wasn't me 

Not the best spot to take A/V signals. Cable looks melted. And no, 1 "well lubricated cap" will not help - spectrum of videosignal is quite wide. Geez, man, whats happened? Not so long time ago we discussed about cables and their shielding.