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27-02-2012, 16:31   #1
 
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Nintendo Famicom AV Mod

A real retro one this, & oddball too. The Nintendo Famicom is basically the Japanese version of the NES. It does have superior sound capabilities, but essentially it's an 8-bit NES. The problem with these is, they are NTSC only only supporting RF out...all you'll get over here is a crappy black & white image.

Enter, the AV mod. Here's the Famicom, some slight differences to the NES as you can see...the joypad cables are integrated into the console [non removable] & are quite short. Pad 2 also has a built in mic which you can use in certain games.



Underneath



The video signal is taken from pin 21 of the ppu [picture processing unit]



It's then fed into this circuit I built. Most guides detail soldering these components directly onto the board, but I chose to use a small section of proto board. It's better for the console, & the video picture will be clearer because the signal will be cleaner.





5v & ground are taken directly off the power regulator, & fed appropriately into the circuit





The video output is then fed to an rca jack. I've one or two spare scart/av blocks, so I stripped one down & cut it to size rather than ordering chassic mounted ones. This will be much more sturdy, & better shielded



That's basically it, the rca jack is connected to the new circuit I built. Time for a quick shake down



What do ya know, it works!



Ok, back to work. I need sound. It's taken off of pin 46 of the underside of the cart connector, & a ground too.



It's then fed to the appropriate connectors on the back of the rca jack



With everything checked & working, I mounted the rca unit into the console by drilling three holes



Time to mount everything inside, & hot glue ot down. This is important because the cart eject mechanism is a moving slider & can easily snag/crush the new cables.



Voila



That's it, it's a nice little mod all in all. Took a while to get the technicalities correct because there's a good few board variations. Sometimes different value caps yield better results than others because of this. Also, there's an additional cap in place between pins 20 & 22 of the ppu to eliminate white bars on bright screen. I forgot to take pics of that bit, but it's done.

I used this guide, & the thread linked within for reference - http://jpx72.detailne.sk/modd_files/fc/avmod.htm

Last edited by Myrddin; 27-02-2012 at 16:59.
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27-02-2012, 18:33   #2
Doge
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Originally Posted by EnterNow View Post



Cute! I think this would be an appropriate moment to ask you a question about your mega drive mod. Imminent bumpage!
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27-02-2012, 19:17   #3
 
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Cute! I think this would be an appropriate moment to ask you a question about your mega drive mod. Imminent bumpage!
Whats the question?
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27-02-2012, 19:42   #4
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Whats the question?

It turns out there's none now!

I somehow confused your display mod, for some kind of "color correction" switch which does not exist!

So I'm good to go!
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21-01-2013, 19:58   #5
Alter Egotist
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Hi all,

Haven't been on boards in a while so hope ye can help. I bought a famicom on fleabay and hadn't looked into the problems you can encounter. After reading about your mod I'm very impressed. I'm have problem with my output however. I have a non modded famicom and a 50/60hz tv I'm using a standard rf lead with a nes rf switch. The power supply is the original and I'm using a step down transformer. My problem is I'm getting no video output at all. Not even the black and white picture described above. Does this mean I have a broken fami? The wrong tv? Wrong rf connector? Or all of the above?

Hope ye can help!

I'm at my wits end!

Al.
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23-01-2013, 13:15   #6
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Originally Posted by Alter Egotist View Post
Hi all,

Haven't been on boards in a while so hope ye can help. I bought a famicom on fleabay and hadn't looked into the problems you can encounter. After reading about your mod I'm very impressed. I'm have problem with my output however. I have a non modded famicom and a 50/60hz tv I'm using a standard rf lead with a nes rf switch. The power supply is the original and I'm using a step down transformer. My problem is I'm getting no video output at all. Not even the black and white picture described above. Does this mean I have a broken fami? The wrong tv? Wrong rf connector? Or all of the above?

Hope ye can help!

I'm at my wits end!

Al.
I'm pretty sure you won't be able to tune it at all using RF on modern TVs... that is if the unit is even functioning.
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25-01-2013, 17:02   #7
 
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that is if the unit is even functioning.
Not working? What do you think this is a modern console!

Anyway, the OP sent me the Famicom to have a looksee. There was nothing wrong with it, its just our TV's don't really like the NTSC signal over RF so there is but one solution - to AV mod it.

The mod itself has changed since I done Atavans one above, so I'll throw up some pics of how I got on with this one:

The OP asked if I could fit the av outputs at the rear of the console. Unfortunately this is where the power board lives, & a big RF modulator amongst other things. You could desolder & remove all these things but I'm not quite sure whats needed & not needed so I didn't fancy using someone elses console as a guinea pig. Safest option is to put them where there's room for them



Instead of adding in a transistor, the recommended way now is to remove this existing one, bend the pins a certain way, & solder it back into place on the underside of the board. Sorry for the blurry pic!







Its also recommended now to build the video circuit actually on the motherboard itself, rather than building it on breadbin board like I did above. Apparently this way the video leads picks up less interference.





Also new is adding this tiny cab between two pins of the PPU.



Time to test. You can see the jailbars pretty obvious here. Hmm, not good!





Ok so after some tinkering, & adding another higher value cap {33uF} cap between the same two pins of the PPU, I was able to reduce the jailbars by some degree, to show this:





Much improved. You can bearly see them at all, though they're not eliminated completely. To do that requires a lot more tinkering about!

Ok so, I'm happy I got the bars reduced as best I can....time to reassemble & finish off.







All done

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24-03-2014, 00:02   #8
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Looking for someone to carry out an av mod to my Famicom, how much does it usually cost?
Mod note: Welcome to the forum and to Boards. If somebody is offering this as a service you can find them in the Services thread at the top of the console modding forum. You can send the user a private message to discuss prices etc. At the top of the forum you can also find the rules thread, where you'll see we don't allow requests like your post so just be mindful in future
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