CGA - VGA converter will work without a JAMMA board, only needs PC and monitor. It will not output a native resolution, only scale to one resolution, and give you some ms delay, but gives you a good result for small money. There is possibility to run software to make your VGA card output 15 KHz directly without a converter, but it's difficult to get right, you can damage your monitor, it doesn't work with all VGA cards, and so on,