Google sci.electronics.repair for "sony video" sony blank video" "Sony
no picture" tons of hits on how to troubleshoot.

Barring that, you need a little more information as there are at least
4 common causes for your symptom and approximately 10 uncommon causes.


I would mark the G2 control and write down the voltage read on G2 and
then slowly turn it up to see if anything becomes visible. That alone
will tell a lot about the problem. Do not run the set in the fault
condition with the G2 turned up, some causes for the loss of video can
crack the picture tube if left with the G2 cranked up.