mvs mv2f ram error write 5555 read b200

[jago]

hi there,

i have a mv2f that i want to fix,

he constantly crash, when i force the test mode with unibios i have this message:

backup ram region write 5555 read b200

when i force to aes, i have a garbled neo geo logo at the splash screen from unibios, then crash with random read/write adress errors and reboot .

i tried to replace one of the 2 backup rams but i found brand new sony cxk5864cm-10ll , i mistaked , and i don't know if that component can work .

i checked traces on the backup ram region, seems to be correct,
also i replaced the battery with a new 3.6 v.

any help will be nice

 

[jago]

also a tutorial with error codes from unibios could be nice ! if somebody can where find one?

 

[shadowkn55]

You need to replace the rams with 256k sram chips. 62256 is the generic part number. Various manufacturers make them.

 

[HeavyMachineGoob]

It sounds like the board also has the click of death, going by "he constantly crash". Check the connections between the BIOS, 68k and Work RAM chips. Go look in my "broken MV-1" thread in Tech Support, it's still on the first page, it contains pinouts for connections between those components.

 

[jago]

You need to replace the rams with 256k sram chips. 62256 is the generic part number. Various manufacturers make them.

do you know any good site to buy them?
thanks!

 

[HeavyMachineGoob]

www.arcadecomponents.com

There's probably electronic part dealers more in your part of the world though, just look around.

 

[Xian Xi]

If it has the 00, it means it's missing control signals. Check the /CS, /OE and /WE lines. Most likely /CS.

 

[jago]

many thanks. i will check again and post when i tested something

 

[channelmaniac]

With that error, I'd check the transistor in the battery backup circuit.