I haven’t done one of these in quite a long time as writing up logs and taking all the required photographs takes up a lot of time and I wanted to power through a lot of my backlog of repairs.
So let’s start us off again with something good…
A bit of back story:
So recently a lot of CPS1 arcade PCB have ended up being sold cheaply on AliExpress and while I was hearing a few horror stories, some people were getting good working boards so I decided to take the risk with a seller “Self Love” to make a test single purchase of a cheap CPS1 Motherboard to see how it would turn out as I would like to have more complete CPS1 stacks instead of having to rely on just my single working CPS1 Dash Motherboard.
So it arrives and it is an all original CPS1 Dash board! A Good start!
I then try to boot games with it and well nothing boots, I cycle through a bunch of B+C boards while testing and my Three Wonders boots up to a SCR 1 RAM NG error:
I check around the board and find many bodged trace repairs:
Corrosion on several pins of a LS253:
and suspect ram that looks like it has over heated on the right hand side:
I really was not happy with the state of this CPS1 motherboard and it simply does not work so I reached out to the seller who then made every nonsensical claim trying to get out of that they sent a broken PCB.
In the end they stopped talking to me and I decided to claim a dispute with them directly with AliExpress.
The sellers only response was:
DO NOT REFUND.
Buyer should close dispute and file claim with courier. We test all our products before sending.
I rejected that and after a few days AliExpress thankfully sided with me and issued me a full refund with no need to return it.
So now I can see if I can repair it.
But after eliminating the obvious visual damage I had already noted, I started looking at the potentially bad SCR Ram and pulled several of them out of circuit:
After looking up schematics for the RAM I learn they can be tested as 62256 but all three fail:
At this point this is not getting me anywhere and who knows what other issues I might run into on this trash condition CPS1 motherboard so I abandon attempts to repair it.
Not the greatest end to my first new repair log in a long time right?
Oh well…