Famicom with scrambled/broken graphics

Started by JetBlackSVW, September 20, 2015, 11:37:50 am

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JetBlackSVW

September 20, 2015, 11:37:50 am Last Edit: September 20, 2015, 04:11:56 pm by JetBlackSVW
Hello,

I have problems with my newly acquired Famicom, on all games I have scrambled graphics like this:

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?

aguerrero810

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?

JetBlackSVW

Yes, the picture is from Rockman 3, a Famicom game, the same also happens with my other Famicom games, Batman and Ninja Ryukenden.

jensma

Moin,

Try to remove the AV circuit, maybe it's causing problems. And check for dripped solder.

Good luck!

HVC-Man

Looks more like a faulty PPU VRAM chip. They're easy to replace and are an off the shelf part.

JetBlackSVW

Okay, which one is the faulty RAM chip?

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?


80sFREAK

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 don't buy, sell or trade at moment.
But my question is how hackers at that time were able to hack those games?(c)krzy

HVC-Man

I've bought a Famicom before with a bad VRAM chip. Replacing it fixed the broken graphics.

JetBlackSVW

So, to be sure I should replace U4, U2 and U1, too?

And where I can buy these chips?

80sFREAK

I don't buy, sell or trade at moment.
But my question is how hackers at that time were able to hack those games?(c)krzy

JetBlackSVW

So, I replaced U4, U2 and U1 with new chips but still the same broken graphics :'(

Also looked for broken traces and found nothing.

HVC-Man

The PPU is bad then. Either find one from back in the RGB PPU days, or get another Famicom.