Famicom AV Modification / Mod

[paletti]

Hi I guess I have exactly the same problem. I got all the parts to do the mod, I made the audio/video circuit and when I opened my famicom it was completely different then the one in the tutorial on this site  Here is a big detailed photo of my board: http://www.signsofshift.com/gfx/famicom.jpg

Then I took a look at http://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http://www.h3.dion.ne.jp/~kuboken/famicom/famav.html which shows the mod for a different mod than the one in the tutorial and I guess it the same board I have but because the photos are so bludy tiny and the crappy translation it's not clear to me what i have to do at all, i can guess where all the parts go but attaching the wires is pretty vague.

Please help me! I'm more than happy to make a new mod page for boards like this to put on this site but I really need some clear (i'm not a pro with electronics) info to understand it myself first!  Thanks!!!

[133MHz]

Use the points clearly marked as VCC, GND, VIDEO and SOU.

[paletti]

Use the points clearly marked as VCC, GND, VIDEO and SOU.

Thanks! I put some more effort into it and I uploaded a new photo (http://www.signsofshift.com/gfx/famicom.jpg)  in which I described how I understand the instructions mentioned on http://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http://www.h3.dion.ne.jp/~kuboken/famicom/famav.html . I might have done something wrong (if so please tell me) but if not I'll give the mod a go. I intend to keep this photo online on my server and hope that it will save other people time/puzzling so please share the photo if it's correct.

Oh yeah and is it necessary to use the 2SC1815 transistor or is the 2N3704 (the one in the tutorial) fine as well?

[paletti]

bump...

[paletti]

Well I gave the mod a go like mentioned on http://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http://www.h3.dion.ne.jp/~kuboken/famicom/famav.html, however I used a 2N3704 Transistor and a 47 uF capacitor. When I hooked it up to my PAL TV (which supports NTSC through the scart) I got a pretty sharp video signal straight away

However, there's no audio at all, although I do hear humming noises and cracks that seem to correspond with the original music in the game. I'm using a 3.5mm stereo jack but i only have 2 wires coming from the board to connect to it (1 signal and 1 ground i reckon) so I guess this might be the problem. I tried different kinds of connection on the jack socket but am a bit scared for short cicuit. Do I need a mono jack to get some sound?

[paletti]

Found out that I connected the audio signal to the wrong point on the board, audio + video is working fine now  New instructions can be found at  http://www.signsofshift.com/gfx/famicom.jpg

[JC]

Just thought I'd post some pics of my AV modded Famicom. Might come in handy for someone, though this mod seems to output faded color. Notice that the white wire, which goes from the amp circuit to the RF port, is audio. The black cord to the right is the video. The gray ribbon wires steal the audio and video from the main board for the amp circuit. The trace for the RF on the small green board is cut, which you can kind of see under the white wire near the RF port.

[133MHz]

Speaking of that, I've recently AV modded my Famicom, which luckily had a board like the one on the site, so I just promptly followed the guide on Famicom World. It worked, except for these:

• Picture was WAY TOO BRIGHT


• Oversaturated, lacking in contrast and color


• Sometimes it would lose vertical sync (picture rolling down the screen)

Coming back to this thread I've seen that some people have the same problem as I am.
Good thing is: I've found a fix. Just add a 75 ohm resistor in series with the video output and there you go! Perfect video!
Try to get a 1% tolerance resistor for this. The more exact the value is, the better .

You might want to consider adding this info to the Famicom AV mod page. I also drew a much nicer schematic if you're interested .



EDIT: Added schematic

[xyzzy32]

I've had a me4taki9oh AV- modded fami for a year now, and I still haven't solved its issue with not playing enhanced cartridge sound. It looks like he does a rather quick and sloppy job of the mod:



Rotated 90 degrees:





It's difficult to see in the pictures (testament to my ancient camera and poor photography skills), but he tapped video from the VIDEO pin (yellow wire), audio from the SOU pin (white wire), then grounded both to the VCC pin, then takes those wires directly to RCA plugs for the TV.
The problem is that this only takes internal-generated sound, leaving out that additional sound from the FDS and other cartridges. Is it possible to capture that sound as well via simple soldering and without additional capacitors, resistors, etc.?

[133MHz]

If the audio is being tapped off the CPU pins, then you're not going to get any FDS sound through.
To get FDS sound you need to tap the audio signal from the point where it leaves the motherboard and enters the RF modulator board.

[xyzzy32]

OK. so I can simply remove the audio wire from the SOU pin and re-solder it to another pin on the main board?

am I getting the right idea here? note the purple numbers on the pins at the bottom of the image.



unfortunately I'm not experienced in this at all, so sorry if I'm not understanding.

[Rogles]

Exactly how difficult is the AV mod to do? I've been thinking of doing this, but I've never used a soldering iron in my life. Should I get someone else to do it? My uncle's pretty tech-smart, he might be able to help.

[xyzzy32]

the cheap version, as was done to my famicom, is actually very simple. get your uncle or someone to show you soldering, which isn't as tough as it looks, and the rest is a cinch, but if you're using an FDS or AD3, I still haven't found out how to get the extra audio.

Edit: Pin 3 (counting from left and looking towards RF modulator) contains the mixed audio, so my A/V modified famicom is now functioning perfectly with a very easy mod (solder just a few wires).

[cheaters5677]

Found out that I connected the audio signal to the wrong point on the board, audio + video is working fine now  New instructions can be found at  http://www.signsofshift.com/gfx/famicom.jpg

Hi I'm new here. Congrats on your successful mod. I just want to know whats the voltage rating on the capacitor you used? And on which side is the + soldered to? Thanks a bunch.

[cheaters5677]

Speaking of that, I've recently AV modded my Famicom, which luckily had a board like the one on the site, so I just promptly followed the guide on Famicom World. It worked, except for these:

• Picture was WAY TOO BRIGHT


• Oversaturated, lacking in contrast and color


• Sometimes it would lose vertical sync (picture rolling down the screen)

Coming back to this thread I've seen that some people have the same problem as I am.
Good thing is: I've found a fix. Just add a 75 ohm resistor in series with the video output and there you go! Perfect video!
Try to get a 1% tolerance resistor for this. The more exact the value is, the better .

You might want to consider adding this info to the Famicom AV mod page. I also drew a much nicer schematic if you're interested .



EDIT: Added schematic

Hi. I'm not much of the electronics guy, but i noticed that your video circuit is way different from the tutorial by Kefka. His circuit has 2 inputs with the +5V on the emitter. Yours on the other hand, has 1 input and +5V on the collector. I'm a bit confused. I may need an explanation.

Where to solder the ground on Kefka's mod is also not indicated. I guess i need help on that too.