Famicom Av Mod problem: Garbled screen.

[Dzordz]

Hi all, I've done the Famicom AV mod but I always get a garbled screen when trying to turn on the console. However, the sound is fine.

Details: I don't know which kind of model is the Famicom cause the back of the console shows it's HVC-002 and the box shows it's HVC-001 (I suppose that it's a HVC-002). The board shows the next kind of CPU: HVC-CPU-07:



I've tried 4 different mods and only works these with the same result: garbled screen.

1. http://www002.upp.so-net.ne.jp/jsrc/densi/fcav.html -> But I use a 4,7uF capacitor instead of 0,47uF as suggest in this website. The transistor I use is NPN 2SC1815 as suggest this website http://www.briconsola.com/esp/p23.htm (and the same site too).

2. http://nfggames.com/forum2/index.php?topic=4055.0 -> I use a 3x300ohm in serie, and 82ohm the other resistor. It just works like the other mod: garbled screen.

The 2 mods I've tried that it didn't work are:

3. http://www.briconsola.com/esp/p23.htm

4. http://old8bits.blogspot.com.es/2013/03/famicom-mod-av-para-el-modelo-esquemas.html

I tried to change the transistor to a BC546 but with this It didn't work (it shows black screen).

I don't know where can be the problem (maybe PPU ?). I've been researching in some forums but I can't find the solution.

Pictures (The game is Rockman 5, but I've been trying with Double Dragon II, Ninja Ryukenden, Punchout with the same results):







Picture of the mod (it can be confuse but I REALLY follow the next scheme)





Video:

View My Video

Thank you in advance !!!!

[KillingBeans]

It's definitely a digital error of some sort. My guess would be that you have either fried some IC (PPU or its RAM?), or you have unknowingly shorted one or more of the lines on the data BUS. It's hard to tell from your picture... It's a mess.

[Dzordz]

It's definitely a digital error of some sort. My guess would be that you have either fried some IC (PPU or its RAM?), or you have unknowingly shorted one or more of the lines on the data BUS. It's hard to tell from your picture... It's a mess.

Thank you for ur reply. I've tried to clean the slot, checked all the connections, etc. and there's no solution. I'll buy another console .

PS: The RF connection has never worked since I've this console, and there's no problem of the RF lead or the TV cause I've a Super Famicom and the RF connection works (very ugly xD but works).

[phreak97]

Your av mod is working perfectly, the picture looks Great.
The problem you're having is somewhere other than the video output section as said above. Probably ram or ppu problems if cleaning the cartridge and cartridge slot doesn't make any difference.
Where are you located? I'm after a dead famicom to steal some bits from.

[Dzordz]

Your av mod is working perfectly, the picture looks Great.
The problem you're having is somewhere other than the video output section as said above. Probably ram or ppu problems if cleaning the cartridge and cartridge slot doesn't make any difference.
Where are you located? I'm after a dead famicom to steal some bits from.

I'm from Spain.