ack

Trace D4.

Confirmed, it was the YM3016 😃

Update: i found the answer in this thread: https://www.neo-geo.com/forums/index.php?threads/neo-geo-not-enough-voltage-current.251251/...

Sounds like its the YM3016.

could be. Another thing you can try is pressing down on different chips / parts of the board while its on and see if anything changes...

warm is usually ok, to hot to touch is not.

Try checking the 68k data pins going into the LSPC. Maybe there is something wrong with D8 (floating?)

It would depend on whats being executed on the cpu. If its the diag bios its likely ok because it puts up the memory error then goes...

work ram wont cause that.

I would guess the error it is complaining about 32K VRAM Upper. It looks like its trying to say ADDRESS: 000000 ACTUAL: 0100...

That image is saying the backup ram has dead output, but AES's dont have backup ram. Are you buy chance holding down C when booting...

I would start by replacing the slow/32k vram chips and see if helps with the screen showing the right data characters...