Dead MVS MV-1F... Sorta?

this one's kind of stumped me.

I have an MVS MV-1F, and it's dead. No games work in it, I get the same scrambled chunk at the top of the screen, and it flickers.

I have two BIOS chips, one SP-S2, the other an SP-U2. I get the identical result with both.

On a whim I burned myself a uni-bios and it works fine! My theory was that maybe the backup RAM was corrupted, it's been a couple of years since I used it last, and that the uni-BIOS (with it's fresh-start approach of paving the save-RAM) had cleared the corrupted settings memory.

But throwing the two original ROMs into the PCB have no effect. They were stored in different places so I have a hard time believing they've both crapped out on me, but what's the other possibility?

Is it just a backupRAM issue? Or something more sinister? <gasp!>

Ideas are welcomed!

sounds more like both of the bios chips are wither faulty of have dirty legs.

Raz

EPROMs don't last forever... bits change value... and if you don't have them covered then they will change due to light too...

If those are the mask proms or OTP proms (no window on them) then it's corrosion on the legs/socket or just plain faulty chips. Check your power supply to make sure your 5v line isn't too high. Logic chips like to run between 4.75 and 5.25 volts. Any lower and things don't work... any higher and things burn up.

RJ

Oxidization is a good idea, I'll have to give their legs a good scrubbing to see if that helps.

I find it odd both chips failed at the same time (or over the same span). They were stored in different boxes, one in an anti-static carrier and the other just stacked in a pile of ICs.

These are original SNK PROMs, not EPROMs. They appear to read fine in the EPROM burner, tho I haven't compared them against a ROM image 'cause I don't have any...

Possible oxidation is my best guess, but the board was well wrapped in plastic in a sealed box, which I'd have thought would minimize the effect.