you could hack a scart cable from a dvd just to see if it gives a picture(using the r,g,b)but you can't leave the picture on too long-to be honest if you work in the trade then just whip out the monitor,take it to work and rig it up on a video cab-like i said before you're going round in circles because you don't know if the fault is on the monitor or the cabinet,you have to prove one is o.k
blanking faults are usually caused by the i/c that decodes the signal from the game board in the monitor itself