CPS3 motherboard graphics issues

PCB problems and fixes
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denson
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CPS3 motherboard graphics issues

Post by denson »

Hi,

I have some CPS3 motherboards that have graphics issues and wonder if anyone can help :(

I've tested my faulty boards, and this time I've made notes so that I don't forget what the issues are!

So, the boards test as follows:

2 x have completely corrupt graphics, and won't let me enter the test menu.

1 x has corrupt sprites and backgrounds, but everything tests OK (memory and Simms)

1 x Sprite Ram: NG 24000000
Character Ram: NG 24100000

1 x Character Ram: NG 24100002

1 x Memory checks all OK, Simms 3-5 show as NG (they are known working Simms Nd the slots have been thoroughly cleaned)

Can anyone shine any light on these issues? Especially the board that tests as all ok as it's part of my SF3 kit... :(

Thanks,
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leonardoliveira
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Re: CPS3 motherboard graphics issues

Post by leonardoliveira »

The RAMs are part of the mainboard, if the test list them as bad, they must be indeed bad.

The board uses a X/Y mapping to label chips. The RAMs related to graphics are:

1D, 2D, 3D, 4D and 5D.

8E and 9E seem to be related to palette (colors).

15J is the CPU work RAM.

Broken traces (corrosion) or broken solder joints on the PPU chip (or other of the smaller chips) may also cause that kind of issue, including RAM test errors (since the PPU chip controls the access to graphics memory) and failing on a test simply means the CPU could not read back what it wrote to the RAM.
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denson
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Re: CPS3 motherboard graphics issues

Post by denson »

leonardoliveira wrote:The RAMs are part of the mainboard, if the test list them as bad, they must be indeed bad.

The board uses a X/Y mapping to label chips. The RAMs related to graphics are:

1D, 2D, 3D, 4D and 5D.

8E and 9E seem to be related to palette (colors).

15J is the CPU work RAM.

Broken traces (corrosion) or broken solder joints on the PPU chip (or other of the smaller chips) may also cause that kind of issue, including RAM test errors (since the PPU chip controls the access to graphics memory) and failing on a test simply means the CPU could not read back what it wrote to the RAM.
Thank you for taking the time to reply.

So in your opinion, is it worth having the ppu reflowed?, and possibly the other chips if that makes no difference? Or are they only good for spares now :(

I will have a better look at them for any damage (broken traces etc) also, just in case.

Thanks again.
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leonardoliveira
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Re: CPS3 motherboard graphics issues

Post by leonardoliveira »

It's always worth the time troubleshoot and try repair when we're talking of old hardware which is difficult to replace. I insist, try everything you can before tossing the board into a parts bin.
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denson
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Re: CPS3 motherboard graphics issues

Post by denson »

8-) :thumbupright: ok, I'll ask a local guy to reflow the ppu chip on a couple to start with and see what happens. I'll report to let you know the outcome :)

Thanks again.
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