Famicom | AV Mod

Success!

[video=youtube_share;w2E6u2D7L40]http://youtu.be/w2E6u2D7L40[/video]

I managed to find a set of 330R resistors (10% tolerance) in the box that my neighbour had donated to me. I used one to begin with (5v > 330R > Emitter). I managed to get an image but the colours were slightly off (as in the previous video). I added another 330R (ve- > 330R > video out [to TV] ) and that seemed to have sorted out the colour issue.. (I forgot to add the 330R before the cap so I've yet to try that out yet).

The image looks pretty good (bearing in mind that my capture device isn't great). The jail bars are only really noticeable when playing SMB, would it still be worth adding a cap to the PPU? (like in the pic above..)

Also there's no mixed sound yet, so Castlevania III will sound a bit weird

 

Ceramic isn't the only non polarized cap made. A quick check via Google shopping:
https://www.google.com/#hl=en&safe=...38,d.b2U&fp=681205aa08f4cf79&biw=1097&bih=568

Lots of hit for 220uF non polarized caps.

 

OK so you're talking about specialty axial NP electrolytics, which are 10+x more expensive and twice as big, for something that doesn't matter since like all amplifiers there's a DC bias, and more to the point there's no reason to worry about "golden-ears" distortion from the capacitor when the actual video signal itself is horrific. Overkill isn't always a good thing.

 

I've actually got a couple of these, I'll give it a try and see if it makes a difference, thanks.

You almost make it sound as if this mod isn't worth doing..

 

I'm going to mod my famicom using this guide http://jpx72.detailne.sk/modd_files/fc/avmod.htm


What wattage should the 100R & 150R resistors be?
What voltage should the 0.1uF, 33UF & 220uf capacitors be?

I don't want to end up buying the wrong stuff so some advice would be grateful. Thanks

 

5v or above i'd imagine....?

Do you really need a cap with the sound?

 

I would think any resistor with a wattage above 1/16 W would be fine. For the caps, you'll be OK with 6.3V or more.

 

Ok, thanks for replying. I though above 5v would be the right choice but I have no knowledge when it comes to electronics.
Going to order alll the stuff know and i'll update you when the mod is done.

 

I have noticed that the values of resistors a caps vary a lot between different guides, are the differing values likely to make much of a difference?

 

I think they vary because people have different experience with different brand of TV or monitor they used.

 

I see, thanks.

 

The truth is that 220 uF (or larger) is ESSENTIAL assuming you're going to connect the FC to a traditional TV. The 33 uF suggestion is completely moronic because in all cases the series capacitor forms a high-pass filter with the TV's input termination (generally 75 ohms to GND). The 33 uF high-pass filter's cutoff is way too high and attenuates the video signal's synchronization component to the point where sync edges are missed by the sync comparator -> an inconsistent, rolling, picture.

Don't listen to self-appointed authorities at FW--nobody knows what they're talking about.

 

I've been planning on doing this mod to my Famicom, and the number of slightly-different (and extremely different) instructions makes it a bit daunting.
The "snarled mass" option of concentrated components directly on the board doesn't seem pleasant.

Since I don't trust my soldering skills too much yet, I was going to assemble on a breadboard. The steps recommended on Famicom World state that the farther away you place the components, the more visible jailbars are. But those steps say nothing about lifting pin 21 and grabbing video directly from there. Would that allow a "remote" solution like a breadboard to work without much added interference?

I'd love to get this "right" the first time...

 

That's why I'm posting on here.. I found a decent guide and bought a solder-less breadboard so that I can try different parts and swap things around, Famicom World is VERY confusing..


My soldering skills are not great so I'm only soldering this thing up once and then I'm done lol

 

Glad to see you got it working! :smile-new: Game on!

 

Thanks, man! Good to see you on here

 

I'm about now and then, more then than now though at the moment! Back to it! (Life outside the internet that is!) :biggrin-new:

 

Ok, did the mod the other day and this is the result with out any cap between pin#20 & #22. As you can see there are jailbars, they look even worse on games like mario bros 3. (Note: this is being played on a sony LCD tv that upscales the image. I think?)
Today I did try to remove the ppu but couldn't lift out the chip. I though I had killed the famicom but it's still working ok. *phew*

I'm probably going to cut pin#21 and take the video directly from there.

 

I just my 2nd video amp,this time I used the AV Famicom circuit and I still have jail bars,even added a 47uf cap to pin 22 on the ppu and still have this problem.

 

I don't believe any video amp will get rid of the jail bars on its own (Something that isn't mentioned in any of these guides). I think the only way is to cut pin 21, shield the ppu and add extra caps to "remove noise from power line".

Here are some of the different video amps I've come across. I've only tried the first one but i'll be trying the others at some point.
The 3rd one down is meant to reduce the jail bars by making the picture blurry?