I'm asking for your help because I have the same problem of black screen with 2 dreamcast.
When the console starts, I have no image or sound, I have a black screen. One of the consoles is equipped with a gdmem and a pico-psu and the other is not modified.
I have of course tried several rgb cables.
I guess the problem is with the motherboard. Does anyone have a better idea of what component would be at fault ?
Thank's for your help.