Maybe there's no signal getting to the monitor. Did you try hooking the monitor up directly to the Sony's VGA port?
Well = every now and again, the monitor mysteriously comes “On”!
So I know it is getting the signal.
However, it is a real surprise when the monitor comes on and it never lasts...it does not flicker. It just goes black again after awhile.
I was wondering if some key on this wireless keyboard was mashed somehow causing this problem because I had not been having this problem up until say about a month ago....LOL Yes am slow getting things fixed...