Hello,
I have problems with my newly acquired Famicom, on all games I have scrambled graphics like this:
http://i.imgur.com/G1vK5Fm.jpg (http://i.imgur.com/G1vK5Fm.jpg)
The background graphics are a broken mess, the sprites look fine though and the sound works without problems.
The Famicom worked totally fine after I did an AV-Mod, I could play Rockman 3 for a few minutes. After that I tried a Pal Mega Man 2 with a NES-to-Famicom pin adapter, it ran fine for 10 seconds then the graphics glitched out.
I already tried cleaning the cartridge connector and reflowing its pins, but no success. The mainboard looks ok optically.
Doe anyone know how to fix this?
I don't know about the graphics, but i do know that PAL games don't work very well on NTSC systems. On Ninja Gaiden for example, the pal version's music is horrendous. on Battletoads, the sprites are all garbled like your picture shows. Have you tried other games with the system?
Yes, the picture is from Rockman 3, a Famicom game, the same also happens with my other Famicom games, Batman and Ninja Ryukenden.
Moin,
Try to remove the AV circuit, maybe it's causing problems. And check for dripped solder.
Good luck!
Looks more like a faulty PPU VRAM chip. They're easy to replace and are an off the shelf part.
Okay, which one is the faulty RAM chip?
http://i.imgur.com/wGGRGZd.jpg (http://i.imgur.com/wGGRGZd.jpg)
What are the exact specifications of this chip? What I have to look for, when I want to order one?
Quote from: HVC-Man on September 20, 2015, 05:36:05 pm
Looks more like a faulty PPU VRAM chip. They're easy to replace and are an off the shelf part.
Not only VRAM(U4), but latch(74LS373) as well. That's something really new, faulty RAM chips ???
I've bought a Famicom before with a bad VRAM chip. Replacing it fixed the broken graphics.
So, to be sure I should replace U4, U2 and U1, too?
And where I can buy these chips?
I would start with U4 ???
ebay.com
So, I replaced U4, U2 and U1 with new chips but still the same broken graphics :'(
Also looked for broken traces and found nothing.
The PPU is bad then. Either find one from back in the RGB PPU days, or get another Famicom.