I'd like to use different arcade boards in my DK Jr cocktail table.
It has the original Sanyo monitor installed. Since I want to leave the monitor and harness unchanged, I will need to invert the colors. I'm aware that having the colors inverted twice (once on a separate inverter board I put together and then again on the inverter board of the monitor) is not ideal, but I'm hoping it will be ok.
I have put together a little adapter, which literally just directs the connections from the Nintendo female bracket to a JAMMA bracket, with provisions to direct the color signals through my separate inverter board.
Now the strange thing is that some of the original boards I've tried work just fine (I haven't got any upright boards, but I tried horizontal ones, like Tetris, Moon Patrol. Colors are good, sound sounds good), but with some boards I'm getting very strong interference on the screen and a 112Hz hum (on top of the usual game sounds). It is like this on an Elevator Action board, and most crucially, as that's what I actually want to use, a Pi2JAMMA adapter (using the Pi for emulation).
Can anyone imagine why some boards play without problems and why the others don't?