Here's a video I made where I poke Pin 21 back and forth between total isolation and regular logic board contact. :gamer:
You can really see the difference it makes!
http://www.youtube.com/watch?v=qxCakPjK7Mc&hd=1
I don't get it...if pin 21 is video out, how can the image get to the TV if you disconnect it from the board?
Regards.
This is the difference between tapping into pin 21's contact on the PCB, and pulling the pin out of its hole to solder a wire directly onto the pin itself.
There's a lot of interference on nearby traces of the Famicom's logic board. Preventing pin 21 from touching the board greatly reduces jailbars when performing an AV mod.
Thanks a lot for your explanation. So, what you did to get the clear image was desolder pin 21 from the board and then do the AV mod as explained here: http://jpx72.detailne.sk/modd_files/fc/avmod.htm correct? did you have to wrap the PPU in copper foil?
Thanks!
I didn't go as far as the copper foil.
Isolating Pin 21 was the biggest reduction of jailbars.
The next biggest change was a 100uF capacitor between pins 20 and 22, like Step 4 in the page you linked. A 0.1uF capacitor (as listed) didn't seem to make a big difference, but 100uF did.