ive got a cmvs based on an mv-2f motherboard
The problem is though, player 2 down won't register over either the controller port or the jamma edge.
Any clues what I should look into?
You'll have to trace back from the jamma edge and check for damaged traces on the board. I have a MV-1C which won't register when A button is pressed but the signal gets all the way to the YSA2 custom so in that case the IC is defective.