What's currently the best AV mod for the Famicom?

Pretty sure I used a polarised cap on mine - wrapped it in heatshrink and laid it horizontal on the PCB. No problems squeezing the case together IIRC either.

 

Sweet, and this is the 100uf capacitor on pin 22 and 20 of the ppu right? What pin did you end up putting the positive leg on?

 

PPU 22 is positive and 20 in ground.

 

Awesome, thanks, I'll go order a polarized 100uf capacitor then

 

What Pikkon said

 

Cool, I've just orderd a set of Rubycon brand 100uF capacitors!

This whole thing's comin' together! I've ordered a 3.5mm 4 Pole chassis-mounted jack, some 300 ohm and 110 Ohm resistors, the aforementioned 100uF capacitors, and I've already got some 220uF capacitors. Ah, I still need to order the cable though! Will any cable with the three RCA plugs on one end and a 3.5mm 4 Pole Plug on the other do the trick?

 

Putting a capacitor on pin 22 makes no sense. 22 is /RESET, an input, and an input that doesn't even toggle! For it to do ANYTHING towards jailbars you'd either really be decoupling 5V (pin 40), or by miracle creating a resonant filter which reduces non-existent noise somehow coupled from /RESET to video, but without actually resetting the PPU....

Since jailbars have a clear pattern--they appear every 8 pixels, they're very obviously switching noise.

 

I see, I did read something about lifting a certain pin and/or removing RF functionality to resolve jailbars. Is this what you're talking about here?

 

?? I'm talking about the 100 uF you're planning to put between pin 20 and 22. That's something FC World came up with to allegedly reduce jailbars, it has nothing to do with composite-modding the FC.

 

Yeah, I know that But on a similar topic, I had read something about disabling RF on the Famicom (by lifting a certain leg on the PPU or something) that's suppose to help with the jailbars. Isn't that what you're talking about when you said "decoupling 5V (pin 40)"?

 

No, its not what he meant by decoupling.

 

That would be pin 21 on the ppu.

 

So disconnecting pin 21 from the board when installing the AV mod should remove the jailbars? :confused-new:

 

The pin is cut or lifted and is connected to the base of the transistor.

 

Cool, thanks for the clarification.

 

Just a random thought with regards to the wiring for the audio, guides I've seen suggest using a shielded wire to protect the signal from interference. In my PC Engine RGB mod thread, it was suggested I put a 1uF cap on the audio to protect the audio signal from interference. Would this also work for the Famicom AV mod? It would be preferable to use Kynar wire instead of thick shielded wire if possible.

 

Unsure mate - these days I always use shielded cable for all AV mods for the internal wiring and haven't had much drama from noise as yet.

 

Here's a video I made of my mod (Kyuusaku schematic) where I poke Pin 21 back and forth between total isolation and regular logic board contact.
You can really see the difference it makes! View in HD for best effect.

 

Hmmmm... I might give it a shot with just the unshielded kynar wire, see how it goes. From the looks of things, pin 21 is the most likely thing to cause the jailbars.

Nice! That really shows the difference! Have you simply lifted pin 21 or have you also attached something to it?

 

I had Pin 21 in its normal position, but with all solder removed. It was perfectly centered, not touching anything
I then scraped my video-out wire up and down the pin so the wire would periodically also touch the pin's PCB's contact point.