Wrong SNES video

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jcarlos
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Wrong SNES video

Post by jcarlos »

Hi, I have a SNES PAL that gives me errors in the video. Attached image. Anyone know what can happen. Thanks
Attachments
IMG20211220193858.jpg
IMG20211220193854.jpg
IMG20211220193852.jpg
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Dwedit
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Re: Wrong SNES video

Post by Dwedit »

Looks like problems between the PPU and the video memory, like some address lines aren't connected properly.

Or it could be a problem where the PPU has an error inside of it where it's picking the wrong address to fetch tiles from.
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jcarlos
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Re: Wrong SNES video

Post by jcarlos »

I have continuously tested the address and data connections of the PPU with the memories and everything seems correct.
creaothceann
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Re: Wrong SNES video

Post by creaothceann »

You'd have to swap components in from another SNES to see what part(s) is/are defective - PPU, VRAM, perhaps even the CPU.
My current setup:
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
jcarlos
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Re: Wrong SNES video

Post by jcarlos »

The problem is that I do not have a hot air station to desolder the components. I only have a 25W soldering iron and a 15W soldering iron. I don't know if that is enough.
jcarlos
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Re: Wrong SNES video

Post by jcarlos »

I already have parts for the SNES. I have got two plates at a low price that did not work, one does not turn on, does not give any signal and the other black screen. I could risk changing the memory of the PPU1 seems easier than the PPU itself, since I do it without a hot air station, but with soldering iron, Flux and tin. Or if someone suggests that I should change something else or if I should change the PPU1 or even the PPU2 I will be grateful.
jcarlos
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Joined: Mon Dec 21, 2020 11:38 pm

Re: Wrong SNES video

Post by jcarlos »

I have replaced both 32K bytes U4 and U5 memories and I get the same result, exactly the same images. I think the next one to replace is the PPU1, which is the one that communicates with the memories, but for this I am going to buy a hot air station. I've seen one at a good price.
jcarlos
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Re: Wrong SNES video

Post by jcarlos »

I have asked for the Super NES burn-in Test, I don't know if I will be able to see that it fails. My question is if what fails is the PPU1, will it mark it for me in the last test where it says APU?
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test.jpg
creaothceann
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Re: Wrong SNES video

Post by creaothceann »

No, APU is the audio processing unit.
My current setup:
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
jcarlos
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Re: Wrong SNES video

Post by jcarlos »

So I can't see a bug in the PPU?
creaothceann
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Re: Wrong SNES video

Post by creaothceann »

Just run Super Mario World again, or the SNES Test Program if you have a SD2SNES / FXPAK Pro / Super EverDrive. You can even compare it side-by-side with the output of bsnes/higan.
My current setup:
Super Famicom ("2/1/3" SNS-CPU-GPM-02) → SCART → OSSC → StarTech USB3HDCAP → AmaRecTV 3.10
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Fisher
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Re: Wrong SNES video

Post by Fisher »

Some time ago, DogP repaired a bunch of Super System Arcades.
They're based on the SNES board.
He was kind to share his logs here.
They were very helpful to me, hope they can help you too. :-)
jcarlos
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Re: Wrong SNES video

Post by jcarlos »

Good. I have reviewed, I think all the connections, between the PPU1 and the video memories and some more connections, but everything seems to be OK. I think that surely, as Dwedit said, it will be some integrated circuit like the PPU1, but I don't know which one, I have spare parts for all of them and a hot air station to extract them, but I have to make sure which one is faulty. Can it also be the S-ENC video decoder (BA6592F), ie the U7 on the mainboard? Thanks.
jcarlos
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Joined: Mon Dec 21, 2020 11:38 pm

Re: Wrong SNES video

Post by jcarlos »

Dwedit wrote: Tue Dec 21, 2021 8:25 am Looks like problems between the PPU and the video memory, like some address lines aren't connected properly.

Or it could be a problem where the PPU has an error inside of it where it's picking the wrong address to fetch tiles from.
Good. I have reviewed, I think all the connections, between the PPU1 and the video memories and some more connections, but everything seems to be OK. I think that surely, as Dwedit said, it will be some integrated circuit like the PPU1, but I don't know which one, I have spare parts for all of them and a hot air station to extract them, but I have to make sure which one is faulty. Can it also be the S-ENC video decoder (BA6592F), ie the U7 on the mainboard? Thanks.
lidnariq
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Re: Wrong SNES video

Post by lidnariq »

Definitely not S-ENC - that's "only" responsible for converting from RGB to YUV and s-video and composite.

My hunch is that either this is something wrong with the PPU's RAMs, and you can replace them, or it's something broken in PPU2 and you can't really do much about it.
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