why do you assume it's the monitors seeing neither work? Couldn't it be your U1?
Or possibly even the video cable.
I'm guessing the U1 has a 13w3 connector on the back, meaning you don't have a pc
or mac to bnc cable (I have a number of each). If you did, you could plug the monitors
into most anything to determine if the problem is indeed w/them. You may not get a legible
picture, or a single one, but that might tell the story. I never had to repair any Sony
monitor, which speaks to their reliability, so I couldn't help you w/repair issues.
The only issue I ever had was when, it seemed, someone rammed a vacuum cleaner into a
GDM-something, that refused to turn on, being the switch was decimated.
You could go the absolute low tech way and use jumper wires to connect a pc say to the Sun
video cable. If you're careful you should be able to determine something. I've
gone as far as to wind coils around tiny drill bits and pushing them onto pins. You get
the picture (I hope).