Famicom A/V Help!

[133MHz]

Well if you want to stick to the RF output no matter what, yes you can just replace the RF modulator board entirely, but you'd need to get one from another Famicom.

As for re-tuning the modulator, inside the metal cage there are lots of inductors (coils). Two of them adjust the video frequency and another one adjusts the sound carrier. You have to stretch/compress each of the video coils with a plastic screwdriver in small increments until you get the best picture quality, then adjust the sound coil until the sound comes on clearly. If you get a clear picture with no sound, maybe you can get away with adjusting only the sound coil until you get audio. I strongly advise against doing this if you don't know what you're doing and/or don't have the right tools. Don't just mess with every coil in sight - you WILL turn your RF modulator into a useless piece of junk!

BTW I'm planning on writing a tutorial about this if there's enough interest and if anyone can provide high quality pictures of the insides of the RF modulator box. Whatcha think?

[petik1]

Fine then. I

[petik1]

OK. As to what you said about the AV, I know there a tutorial on he site, but could you explain to me how to fit the jacks through the switch "holes" in the back? BTW, I'm all for the tutorial!

[133MHz]

To avoid drilling holes and ruining your Famicom's pristine appearance forever (I'm picky about that, too) my idea was to take advantage of the holes left by the missing switches to route an AV cable from the inside of the system to the outside, for plugging into your TV. Here's a picture of my Famicom, this is what I'm talking about:



Mine came without that switch (hardwired into CH1), so I took advantage of the situation and used its hole for a non destructive AV mod.
Whatcha think?

[petik1]

Ok, that looks excellent! So what exactly did you do? Cut off the other end of an AV cable, and solder it on to certain areas on the board? And I see that the cable are yellow and red. Would white work instead of red, or are they both just the same?

[manuel]

White or red doesn't matter, they are the same except the plug color.

[petik1]

Ok, thanks. Cou

So what exactly did you do? Cut off the other end of an AV cable, and solder it on to certain areas on the board?

Could someone answer that?

[133MHz]

Correct. Get an AV cable, cut off one end, solder the wires to the FC motherboard. You need to build a small video amplifier to get adequate brightness though. It's so simple that you can just solder the components together without using a circuit board. Also the components are really cheap and easy to find. You can replace the C1815 with any suitable low power NPN transistor.



Show this schematic to your neighbor. If he can build this, the AV mod is yours!

[petik1]

YES!!! Thanks guys your such a help. Ill check out the specs, supplies, the AV mod wep page, and i'm done! Thanks alot!!!

[petik1]

Do you think you could take pics of your video amp, the +5v, the audio input, and the Ground  if you don't mind? Just somthing as a reference.   And what is that R3 75 on the diagram? I have everything found, but that.

[133MHz]

My pics won't be of much use to you because:

• I've built the video amp in a printed circuit board, and


• There are several revisions of the Famicom motherboard, with different soldering points. My board might not be the same as yours.

R3 is a 75 ohm resistor, simple as that .

If you need help with assembly, don't hesitate to post .

[petik1]

Excellent! What would you suggest? On a printed circuit board? Because I went by Radio Shack yesterday and saw one. Or would it be easer just to solder them together? And I don't know if this will help, but i've got a 1984 board. Where do I solder on the +5V and the audio input? I clearly see where it is marked VIDEO and GND on the board but nothng else familiar...
Here's a picture of a 1984 board similar to mine with minor differences but it shouldn't affect anything.
http://yfrog.com/4ffamicomboardrearzr8j

Also, I'm having trouble finding that 75 OHM. I went to radio shack and no luck. Is this what I need? http://cgi.ebay.com/PACK-OF-100-75-OHM-5-RESISTORS-RADIO-SHACK-1-4-WATT_W0QQitemZ360173163796QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53dbfe5514&_trksid=p3286.c0.m14

[133MHz]

Excellent! What would you suggest? On a printed circuit board? Because I went by Radio Shack yesterday and saw one. Or would it be easer just to solder them together?

I suggest just soldering them together "in mid-air" because of space constraints. I've built it in the smallest circuit board I could possibly etch and I had a pretty hard time fitting it inside the Famicom. It's a really tight fit in there .

Also, I'm having trouble finding that 75 OHM. I went to radio shack and no luck. Is this what I need? eBay Link

Yes, those are exactly what you need, perfect for modding 100 Famicoms .

Where do I solder on the +5V and the audio input? I clearly see where it is marked VIDEO and GND on the board but nothing else familiar

The audio point should be labeled SOU (as shorthand for SOUND). The +5V supply is a little bit trickier, you can pull it from lots of places, this is a good place if you've got this particular motherboard revision:



Also there might be a point marked VCC, if there is you can get your +5V from it.

[petik1]

100 famicoms? Sweet... I guess then I'll order those resistors and wait for my neighbor to come back from vacation. You've been a real help, thanks! I guess my last question is, is there like a rubber stopper to put on the cable right before the hole so that if I pull on it the solder doesn't break off? If not, I'll just improvise...

[cubelmariomadness]

Tell us how it turns out afterward.