Is my game gear power adapter inner positive or inner negative?

Hi,

I have a a Game Gear VA1 (Europe version, 837-9130), the power board has number 171-6391B (also has 837-9131). I don't have the power supply, but before buying a replacement I wanted to make sure whether I need a 9V adapter with inner positive or inner negative.

I can't figure it out from the Power board, does anyone know why one I would need?

Thank you!

Simone