A few years ago I traded someone on here (I forgot who!) a nice original Coregrafx I for a PAL unit. I just wanted to see what was inside it. There was an RF unit, but attached to it was a custom PCB featuring a CXA1145, which is the video encoder that was used in the Genesis/Megadrive, Amiga, etc.
You should be able to remove all this and solder a DIN socket back in, but if I remember there was a missing capacitor or two, and maybe some other components missing. I don't remember how the 50/60hz was dealt with though.