Street Fighter 2 extra dip switch..??

[BaldiGit]

Hi All,

Does anyone know what the forth set of dip switches are on board 'B'?

I have a very odd CP1 Jamma Street Fighter 2 Champion edition board, that I think has a bootleg 'B' board. Both the 'A' and 'C' boards have Capcom silk screened on them but not the 'B' board. From pictures on the web, it looks exactly like a Final fight or a Magic sword board. Accept all the chip sockets are populated and the kick harnes is on board 'B' along with this extra dip switch...

The board functions ok, but with issues. I recieved it with all the dip switches in the off position. And like this the sound is occasionally distorted and the sound effects come and go. By fiddling with the extra dip switch the sound comes up perfect, but then the board randomly resets and random blocks of missing video occasionally appear.

I believe this dip switch is for the chip type settings. But I have no idea of the correct combination. Has anyone got one set correctly? Or knows what it should be?

Many thanks for reading