CPS3 Character RAM error

[kazuo]

Hey all!

One of my CPS3's decided it wanted to start randomly glitching out, so I ran a memory test on a whim and got the following:

CHARACTER RAM NG 24100000

I did a visual inspection of the traces and vias on both sides of the board around the RAM ICs, and I probed the PPU pins in case any of them came loose... didn't find anything unusual. :/

The only thing I really dug up during some searching was this thread from TheCrow, detailing that the character RAM is at location 2D-5D; this seems to line up with what's in the MAME driver. I assume the value in the error code is some address in RAM, but I haven't the first clue how to figure out which IC it maps to, and I'm reluctant to shotgun the chips if I can simply replace one (assuming that only one is a problem)... does anyone know how I might be able to figure out which IC I want to try swapping out first?

Thanks!

 

[GoldenGlover]

My guess is that it’s at 2D given the error begins with a “2”. Try replacing that one first & see if it fixes things.

 

[kazuo]

Was leaning toward that myself... glad to hear I'm not the only one. Makes me feel better about the time investment.

Appreciate the tip! Keep 'em coming, folks.

 

[kazuo]

Unfortunately this did not work - getting the exact same error. I made sure to inspect all the traces and vias under the chip, as well as buzz them out. No apparent issues.

I have another board I can use in the meantime, so I will slowly get around to just shotgunning all the chips unless someone knows how to map that address to a specific chip (presumably it is either 3D, 4D, or 5D?).