Does anybody know what I've done wrong here?
This is a Jamma PCB going to the RGB scart input on my TV. The board output is fine when going into a scaler/line-doubler thing I've got. The TV is fine when plugging in any RGB game consoles. I get the same effect on another spare CRT too.
It's not really a black and white image, it's almost totally black with only the outlines of sprites etc visible, these pics were taken with brightness wacked up full.
The Jamma harness has a plug with R,G,B,GND,SYNC wires. Those are going to the appropriate pins on the scart plug, as shown in the OP. The only difference is I'm using one GND wire daisy chained to all the returns, instead of lots of seperate grounds... is this what's causing the problem? All the grounds are joined together on the board anyway so I don't see how it would make a difference.
I've added +5V to the blanking pin 16, this made no difference good or bad. I added a 100 Ohm resistor to this wire, still no change. I added 150 Ohm resistors to the RGB wires, obviously this doesn't help either. I haven't sent any voltage to pin 8 since I can just use the remote control to switch to the scart channel for now.
(My theory was if I can get this simple board working then I'd tackle the whole vga soft-15khz thing next...)