ok i was reading over at hackaday
they used this same board..btw it is what turned me onto it
here is some of it
>The only way would be to use video downscaling. This part was hard to solve. We knew we had to downscale our 31Khz VGA signals to 15Khz RGB lines and this is no easy task, it requires powerful video algorithms and heavy processing using dedicated chips. Professional equipments to do this job usually cost hundreds of Euros (or more).
So we though we’d go through the old underground forums and dedicated pages for arcade parts in the hunt for a solution. And we found it.
Our pick is the GBS 8100. This beautiful piece of hardware takes VGA input at 31Khz, downscales the video and is able to output it at 15Khz over RGBS pins (which can be connected directly to the arcade CRT board, cable included), VGA db9, RCA composite video or S-Video. Furthermore it has an OSD menu system and you can calibrate brightness, contrast, video offsets and other details. Requires 5V to operate. And it costs approximately $30.
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>link
http://hackaday.com/2012/12/17/using-arcade-monitors-with-the-raspberry-pi/<
come down to the part about using a rasberry pi..follow the gbs-8100 link
ed