SNES SNES OBJ L OVER FAIL using test cartridge.

[Ergot]

This is the first time I have got anything other than all PASS or just a black screen. The SNES works but has graphical glitches. Can somebody whittle it down to a specific part/trace from the OBJ L OVER FAIL!
Thank you.

 

[bart_simpson]

ppu or cpu

 

[Pikkon]

This site has awesome info.

DogP's Nintendo Super System page

 

[Ergot]

This site has awesome info.

DogP's Nintendo Super System page

I have read through this page before and it has a lot of useful info, but there is nothing about the OBJ L OVER Fail.

I'm thinking it could be the PPU2 chip. I have some spares so I can replace it, but I wanted to narrow it down so I don't have to remove and replace too many chips.

 

[Ice Man]

According to this schema: https://console5.com/techwiki/images/d/dd/Snes_schematic_color.png
/OVER is located at PPU1 (Pin 94).

OBJ (OBJect) is also known as OAM (Object Attribute Memory) afaik. Which is indeed located in PPU1.

 

[Ergot]

I wish I had this information before I started removing chips. I replaced PPU2 first, which obviously did not fix it, but at least I know that the original PPU2 chip is working and could be used as a replacement in future.
Replacing PPU1 did fix the problem.

I wonder why the PPU1 chip didn't undergo any revisions like the CPU and PPU2 chips? Even the S-WRAM has a revision B. The DogP page that was linked mentions several PPU1 failures.

 

[Ice Man]

Glad it is fixed now. As to why there's no other revisions. No idea, but my guess is they wanted to save costs before producing the 1-CHIP SNES perhaps? I still prefer the original 3-CHIP version (PPU1, PPU2, CPU) to be honest as it has better compatibility compared to 1-CHIP and is more stable. The only downside is the video quality.