Sega ST-V EEPROM Check BAD

[yavuzg]

Hey guys,

What might be the cause of the "EEPROM check" on ST-V shows up BAD?

Changed the BIOS, cleaned the socket, still shows BAD. The boards boots up fine though...

 

[deibit]

do you have a multiregion BIOS?

In my case, i get a failed EEPROM check with the multiBIOS installed, replacing it with the original BIOS removes the error.

I can play for hours and nothing happens thought.

 

[yavuzg]

The original BIOS also shows BAD and then I programmed a modbios v1.11 and that one also shows BAD. However, my other ST-V mobo in the cabinet also has modbios on it and it does show GOOD, go figure...

That particular ST-V in the cabinet (which shows GOOD) is a newer revision mobo though (i.e. there is no patch cable on the back side).

As you said, neither has problems in game play...

 

[stj]

try a new eeprom, they do die.
it's only an 8pin chip.

 

[yavuzg]

try a new eeprom, they do die.
it's only an 8pin chip.

I thought that the "EEPROM Check" is the BIOS check (although the BIOS is and EPROM). Which one is the EEPROM then?

 

[skate323k137]

I would guess it's used for test mode settings. Try changing options in test mode like credit cost or game difficulty and see if you lose them after poweroff on the board with bad EEPROM.

 

[yavuzg]

OK, solved my problem!

Thanks @stj for pointing me the right direction...

To summarize, I was getting this...

I've examined the ST-M mobo to find out which chip might be the EEPROM and finally found it. It is identified as IC101 and also AK93C45F is written next to it.

I removed it...

And snatched another one from my parts board (this IS a parts board. Funny thing about it is that someone even tried to repair it at one time) I got it from the local operator for free

Soldered the salvaged EEPROM hoping it is still working...

And re-tested the EEPROM...

So mystery is solved, at least for me that I always thought this test is related with the BIOS EPROM which apparently was not.

 

[l_oliveira]

As with any kind of writable non volatile memory with erase cycles (nandflash, eeprom, norflash) there's a finite number of times it can be erased. When that expires it's no longer writable and there's where that error comes from.