Neo Geo CD with graphical glitches

[Hawwa]

Hello there!

I've recently bought another ngcd (I know, really, I do know) and this unit has graphical glitches, otherwise works perfectly fine.

Tried swapping the CDA board with my other ngcd (which works just fine) but the problem is still there, so I'm ruling the CDA board out of the table.

I've checked the mainboard thoroughly but couldn't fine anything worth noticing. No corrosion, nothing seems to be missing, broken, not connected...

Any suggestion as where to start looking?

 

[Hawwa]

Nobody? Not even a small clue?

 

[HeavyMachineGoob]

Could be a bad VRAM chip, maybe both. Does the NGCD still use 32KB SRAM chips for that? I never bothered to look last time I was in my front loader.

 

[Hawwa]

I guess I'll be needing an oscilloscope in roder to check those VRAM chips, I'm I right?

I'm not confident enough to try swapping the ones in my working one to try them on the bad one and see if it works that way...