SNES won't turn on 2

Discussion of hardware and software development for Super NES and Super Famicom.

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marcorosa13
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SNES won't turn on 2

Post by marcorosa13 » Mon Jan 25, 2021 11:09 pm

Hi, I have this issue, can anyone help me?
I change all caps, and the problem still there
I change the VA1 and nothing happend

https://youtu.be/ueK9pKLF02w


I turn on (led indicator works)....since a while, It looks a black screen, and then nothing.....and the led indicator is still on

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Fisher
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Re: SNES won't turn on 2

Post by Fisher » Tue Jan 26, 2021 6:24 am

I've heard that most of the time the cause of the SNES' black screen is related to problems on the CPU or WRAM.
It's good if you can get a test cartrige and try to run it.
But depending on how bad the CPU/WRAM is it won't even boot.

Would be possible to disable the onboard WRAM and piggyback an SRAM, just so it can try to boot the test cartridge?

marcorosa13
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Re: SNES won't turn on 2

Post by marcorosa13 » Tue Jan 26, 2021 1:08 pm

Sorry, but how can I disable the WRAM? there's any guide around there?

gorgyrip
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Re: SNES won't turn on 2

Post by gorgyrip » Tue Jan 26, 2021 1:25 pm

wram=work ram. how the console will "work" if you disable it?

I have never seen a dead wram. Most of the time is the cpu. Very rarely it's a broken trace.

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Fisher
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Re: SNES won't turn on 2

Post by Fisher » Wed Jan 27, 2021 3:39 am

According to these logs WRAM is the second most common cause of non-booting SNES-like systems.
The suggested test I have in mind is to pull up the enable pin of the chip so it won't be enabled and piggyback another one for testing.
If there's a quick way of doing this it will become a nice time saver for non-booting SNESes. :-D

Or there's a better way to figure it out with a scope or logic analyzer?

lidnariq
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Re: SNES won't turn on 2

Post by lidnariq » Wed Jan 27, 2021 12:32 pm

I think my take-away from helping diagnose poot36's SNES is that unless you have a pool of multiple SNESes with failures, and a hot-air rework station, it's just too hard to fix most failures, so it's not worth it to do more than cursory testing (i.e. vreg, fuse, CIC)

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