MVS 6 Slot Backup Ram Error - help!

Hi,
Just bought a 6 slot MVS board with a known backup ram error for cheap…..
Booted it up with a regular bios and it reads:
Address Write Read
00D00000 5555 FEFE

Then booted it with a unibios (2.1):
Address Write Read
00D00010 5555 0010

On closer inspection it seems the 3.6v lithium battery that feeds the backup ram etc had suicided (prob. to do not only with the age, but the after market memory flush switch that had been fitted…)
So, I removed the old battery and tested without – got the same error. Installed a fresh battery, flipped all the harddips to flush the memory, booted again to the same error.
I’ve tested pin 28 on the backup ram with the new battery, and both have 3.6v current running through them……
The MVS won’t be forced to boot in AES mode either – comes up with a more indepth memory fail screen (am at work at the mo’ so can’t post this up). However when I try to force AES mode, then press C to reset, the unibios splash screen comes up without the Neo Geo header.
Any help would be appreciated to solve this1
Cheers in advance,
Dan.

That's a hard RAM error, not a corrupt RAM error... You either need to replace the 62256 RAM chips or you have a broken trace and need to fix it.

When the battery suicided, did it leak on the board? If so, you may have some traces that gotten eaten up and need to be fixed. More common of a problem than it should be.

RJ

Cheers RJ,
The battery had leaked on the board, thought i'd repaired all the traces - maybe I missed one....looks like I'll prob. buy a couple of 62256's from your site just to be safe.
Cheers again,
Dan.

Thanks, but I don't have any of the SMT types.

You can order them from Mouser.com - Part number: 870-IS62C256AL-45ULI

They are a great company to deal with - plus they are local to me. They have a warehouse on the South side of Ft. Worth, TX - just across the Metroplex from me.

Raymond