Need help trying to understand SNES Burn-in Test Cart result

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pkmpad
Posts: 2
Joined: Sun Nov 11, 2018 2:53 pm

Need help trying to understand SNES Burn-in Test Cart result

Post by pkmpad » Sun Nov 11, 2018 3:08 pm

Hello everyone.

Today, I finished my repro Burn-in test cartridge. I tried in my three non-working super famicoms, but I would need some help for understanding what do the errors mean, where do they come from and wether there is any possibility to fix them. I have attached photos of the results to this post.

SFC number 1:
This console is able to load games with good sound but terribly glitched graphics. I suspected from bad PPU1. The results of the tests are totally glitched. It is possible to see a red result in the third option from the bottom. Should that correspond to OBJ L OVER? If so, what does this mean? What is the chip responsible of this failure?

SFC number 2:
This system is able to load games untill sound is supposed to be emmited, when it freezes. It acts exactly the same as a SFC with the sound board removed. I thought it could be a bad APU (replaced the sound board with a working one and the problem persisted). The results of the tests indicate a bad OAM (01 FAIL). How should I interpret this? Is it a bad CPU?

SFC number 3:
Not even able to load the cartridge. No video output (neither a black screen). Revised and good power circuit and capacitors (LED turns on and every IC has enought voltage supplied). I have an oscilloscope to test the board depper. Any advice about where should I start? I know this may also be a bad CPU. Any way to get sure about that?

Any help will be welcomed.
Thank you very much.
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WhatsApp Image 2018-11-11 at 14.39.27.jpeg
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Nicole
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Joined: Sun Mar 27, 2016 7:56 pm

Re: Need help trying to understand SNES Burn-in Test Cart re

Post by Nicole » Sun Nov 11, 2018 3:34 pm

OAM is the memory used for sprite attributes, which is located in PPU1.

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Fisher
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Re: Need help trying to understand SNES Burn-in Test Cart re

Post by Fisher » Sun Nov 11, 2018 3:53 pm

According to these logs, a black screen on a SNES has lots of chances to be caused by a bad WRAM.
There's also some more explanation about other errors. Hope this helps!
Good luck!

pkmpad
Posts: 2
Joined: Sun Nov 11, 2018 2:53 pm

Re: Need help trying to understand SNES Burn-in Test Cart re

Post by pkmpad » Sun Nov 11, 2018 4:07 pm

Nicole wrote:OAM is the memory used for sprite attributes, which is located in PPU1.
Nice. Then, does that mean that I should replace PPU1? It seems strange to me, since everything pointed to a failure in the APU or sound system. Any clue about what is that 01 code?
Fisher wrote:According to these logs, a black screen on a SNES has lots of chances to be caused by a bad WRAM.
There's also some more explanation about other errors. Hope this helps!
Good luck!
Thank you for the link. According to that, it may be either a bad WRAM or a bad CPU. Any way to test the CPU with an oscilloscope?

Thanks.

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