Bally S9000 MBR fail after swapping MPU

[Elbandingo]

General description of problem: MBR error after swapping MPu that had bad nvram

I originally had an issue with nvram battery being low. Swapped, cleared, all was fine. Couple months pass, and sure enough battery dies again. New batteries, doesn’t clear giving error that nvram clear failed. After searching through many forums, the consensus was to replace MPU. Sourced an MPU on eBay all it was missing was BIOS and JUR chip. When it arrived, I swapped the bios and jurisdiction from old bad board to new one. Booted it up with clear card in it. Gets error after doing a memory check that MBR is failing.

I am lost as to why. When I moved the chips back to the old machine, it lets me boot to clear screen but I still get an nvram clear error. I believe I am missing some important information that might be related to the specific MpU replacement I bought even tho the board is identical. See specs below


Old board: PCA39456-0-0 rev D 428330-0738
Bios: AVBPROD807-00
317 OS
312 clear


New board: PCA39456-0-0 rev E 428330-5006


When I put the bios chip in, it is recognized on boot, and even matches previous display when I’d boot the bad board.

[Elbandingo]

To add to this, I do understand there is a matrix out there that shows what OS and clear is needed based on the BIOS, but given that I’m keeping the same BiOS, I would think my OS and clear are ok

[rickhunter]

You may have a bad cf reader on the new mpu, have you tried using the other slot for the clear card.  If it works on the other slot, it means there's probably a missing or bent pin inside the cf card reader of the slot that failed.