[Solved] CPS2 White screen

PCB problems and fixes
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darkcrono
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[Solved] CPS2 White screen

Post by darkcrono » April 14th, 2019, 8:16 pm

Hi otakus!

I have a problem with a SSF2J, when i fire up the cab, it shows a white screen, i cleaned the whole B board with IPA alcohol, it sometimes boots when i unplug it and plug it back (hard :fastlove: ) but only some times and if i put back the case, i don't manage to make it work, only decased, tried 2 different A board same problem, and other B board on both, working like a charm in the first go, I need some pointers, the white screen is sympton of what? the battery had 3,7 healthy volts when start trying it, it behave like this since i got it, as i managed to boot it randomly, i took out the battery, shorted the cap and made a nobatterycps2 job (arduino nano injecting the keys on boot). I got it working decased with this setup with the same plug out plug in hard system, but when casing again, no luck, some crc in the pins didn't do the job neither.

Please gurus and enthusiasts throw some light in my despair :awe:
Last edited by darkcrono on April 24th, 2019, 8:04 pm, edited 2 times in total.

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leonardoliveira
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Re: CPS2 White screen

Post by leonardoliveira » April 14th, 2019, 11:46 pm

Try it with the B board disassembled. If it works every time, mount it on the casing and press the connectors in with your fingers, check if they bend in when you push. If they do the casing is damaged and need repair.
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darkcrono
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Re: CPS2 White screen

Post by darkcrono » April 15th, 2019, 12:30 am

Thats how i (sometimes) make it work, the bare B board against the cased A board, and it's the only way i saw it working... I read here and there, suicided boards display blue or purple, black if dead for other reasons, but i don't find white screen meaning, i thought i could sort out faster with the reasons behind a white screen...

Thanks a lot leonardoliveira for your time and interest

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leonardoliveira
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Re: CPS2 White screen

Post by leonardoliveira » April 15th, 2019, 2:47 pm

The color on the solid screen when it did not boot is not a signal of anything, each unique board chipset has a tendency to power on in a specific state by chip production characteristics. It varies from A board to A board. And it means nothing.

Edit: Depending on how the games are programmed, some test if the QSOUND circuit is operating properly before clearing the video registers, which means it may crash at a solid colored screen if the Z80 or the roms 01/02 are bad or missing.
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darkcrono
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Re: CPS2 White screen

Post by darkcrono » April 15th, 2019, 7:55 pm

I'll check continuity and so, it's hard to Tell when it randomly works... Thought about the psu, but tried in 2 diferent cabs...

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darkcrono
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Re: CPS2 White screen

Post by darkcrono » April 24th, 2019, 5:29 pm

I was reading about the cps2 security in eduardo's blog, aside of a very instructive and interesting reading, did not find a solution for my board, i was about to check traces and so to the two customs assigned to the encryption process, but i wanted to see how a dead cps2 looked like, so i killed a Dungeon and dragons i had around, and the behavior was pretty much the same, so i ran another test on my ssf2j, and unplugged the vcc of the arduino nano, and plugged it after the white screen, the keys where successfully injected and working like a charm, i'll add some delay on the key injection of the arduino, problem solved.

I'll like to thank leonardo for his time, and hope this will help other users in the near future.

As using the arduino way keeps original roms, it's cheapper than a battery, prevents suicides, and removes the dread leaking battery, this should be the way to preserve boards.

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leonardoliveira
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Re: [Solved] CPS2 White screen

Post by leonardoliveira » April 25th, 2019, 2:32 am

The problem is not a delay or anything, two of the signals used to setup the key writing are actually bus control signals, the arduino must release them completely after programming the key, so turn them all into inputs so they don't affect the board when key programming is done.
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darkcrono
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Re: [Solved] CPS2 White screen

Post by darkcrono » April 25th, 2019, 5:53 am

The thing is that even when it was "working" with the battery (3'7v measured) had the same issue, and the screen was white yellowish, and managed to boot like twice.

That's why all this case was so confusing for me.

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Re: [Solved] CPS2 White screen

Post by leonardoliveira » April 25th, 2019, 2:24 pm

Well, it's not made to have something connected there all the time, you see. lol
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