Problem NEO-GEO MV2FS blank screen, no boot.

[Georgian2]

Hello,
here I have an 2 slot neo-geo mvs motherboard. It first boots to ~1 second of green pixels then darkness on the screen.
If i short some pdata pins on the 27C1000 on position C5 I get the folowing screen. I did swap the two srams on B8 (KM62256CLG-7 should be faster) but it dosen't make any difference.

Anybody got experience with these boards? Maybe the work ram is bad?

Any help is appreciated.

 

[Georgian2]

I swapped the two CXK5864BSP-10L from the B8 with no difference at all. Something in between must be at fault. I'm not familiar with neo-geo this is my first repair attempt.

 

[Georgian2]

quick update....
I put the latest unibios in it and it starts the game but massive color/graphics issues. most of the lower addresses on the pallete ram are stuck low. these come from the neo-b1, so thet fat custom must be bad.

 

[Georgian2]

Acording to this website the neo-b1 handels the address lines between the 68000 processor and the srams. Maybe I ccould find a way and bypass these address lines... Maybe I should salvage my slot ne-geo for this?
If anybody knows if I can bypass this IC please do let me know.

 

[Georgian2]

So, I swapped that NEO-B1 with an working one from my 1-Slot motherboard. Testmode works with all the colors, no error at all, however graphics problem. Everything is messed up. Any ideea what could be bad? I did try 3 cartiges and all are the same. The cartiges worked well in the 1-slot thing before I sacrificed it.

 

[Ace`]

neo-zmc2 most likely or traces in that area if the battery has leaked.