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Bad Motherboard or Bad Repro Cart?

seggy

seggy

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Hey everyone!

Took a gamble a few weeks ago and bought a CPSIII from the 'bay. It came "untested", with a Darksoft repro cart and a full set of simms. Everything on the board and cart seems to be in good shape visually.

Unfortunately, I am getting garbage graphics both with and without the cart inserted. They are different however.
I have done the following in my troubleshooting:
-Reseated the cart MULTIPLE times.
-Verified a nice and even 5V on the jamma edge.
-reseated all the simms and cleaned their contacts (shouldn't be necessary to boot from my understanding, but why not)
-lightly took some 2000 grit sandpaper to the edge of the cartridge
-reflowed the bios/29F400B, just in case.
There was testing between each of the steps above.

After cleaning the contacts of the cartridge with 2000grit, I began consistently getting a garbage screen I would only occasionally get before:
Sad_Garbage.jpg


It is 100% identical nearly every powerup with the cartridge now (may need to seat twice if I remove the cart).
Searching through the CPSIII Section of the forum, I think I only saw one occurrence of a repro cart failing? I'm not sure if I should consider a consistent garbage display a good sign or a bad sign. I understand that the main issue is that I am testing unverified gear with unverified gear - just looking for some insight.

Has anyone ever had a similar experience? Specifically a consistent garbage display? I think my next step is trying to find someone to send the cart to test/replace the bios if necessary, or purchase a programmer to do it myself.
Any feedback is welcome, thanks!
 
Ah yes, the rabbit hole of untested test equipment :-/ you have my sympathy.

As you’ve rightly said, it’s highly unlikely that the repro card is bad, darksoft engineers a reliable multi :)

Those garbled graphics don’t look like “bad bios” to me, they look way further down the stack, it doesn’t even quite look like 240p…

I’ll check my notes (repaired 4x CPS3 recently) and come back, in the meantime, quick question, are the garbled graphics static, or do they move around. And are they the same each time, or different?
 
hatmoose said:
Ah yes, the rabbit hole of untested test equipment :-/ you have my sympathy.

As you’ve rightly said, it’s highly unlikely that the repro card is bad, darksoft engineers a reliable multi :)

Those garbled graphics don’t look like “bad bios” to me, they look way further down the stack, it doesn’t even quite look like 240p…

I’ll check my notes (repaired 4x CPS3 recently) and come back, in the meantime, quick question, are the garbled graphics static, or do they move around. And are they the same each time, or different?
Click to expand...
Thanks for looking into it!
They are pretty static - there is some continuous movement and slight variations to the white blotches in the background but the green web-like overlay is pretty constant. I've uploaded a video of a few powercycles to illustrate: imgur (the first and last screens look like identical images)

I agree, based on what you posted and the other posts I've checked out this looks pretty new to me. That said I'm no pro though.
 
CoolFox said:
Reflow the GPU
Click to expand...
I will probably end up doing this but want to verify the cart first - while I trust my reflowing skills I would be lying if I said I haven't fried an IC before:whistling: Plus I hear these customs are pretty fragile.
 
seggy said:
I will probably end up doing this but want to verify the cart first - while I trust my reflowing skills I would be lying if I said I haven't fried an IC before:whistling: Plus I hear these customs are pretty fragile.
Click to expand...

If you are uneasy about doing it, send it to Ken @ irepairsega.
 
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