Sorry for bumping this old thread.
I don't have much experience in modding, I only did a stereo mod on a PAL NES.
I'm going to buy too a Famicom AV, but since the audio and video are mixed I'd like to mod it to get the audio through RCA like the NES mod.
I kinda hardly understood the docs on emu-docs.org, but I can assume safely that there's no real difference between the NES and the Famicom except the shell and the top loader, right ?

just crack it open and look for the 2A03 chip.  I forget which pins the squares and tri/DPCM/noise are...  I think you can probably find that info on emu-docs.org.  You can wire up the two points on the chip and the two grounds (or daisy chain with one ground point coming off).  It is probably good to put a signal diode (something like a 1N4001) or a fuse on each of the lines before it heads into the rca jack to prevent reverse current from blowing the 2A03.  the 2A03 is much more delicate than the Gameboy sound chip.

Hello, I have little experience with hardware modding but have been really interested in the stereo mod for the NES perhaps like in this video http://www.youtube.com/watch?v=RLGo_P-MNG4. However, I own a "New AV Famicom" HVC-101, and haven't been able to find tutorials written specifically for this model and particular mod besides this one in Japanese, http://homepage3.nifty.com/F-LABO/ProductsList.html just wondering if there were any alternatives.

Thanks in advance for any help!