Hello,
I have a SOny KV-35S42 that seems to be doing much the same thing.
Picture comes on fine at first, then in a minute or two, it comes on
and off at around 2 second intervals. The picture seems to be fine
when it is "on". I have been looking into the ABL circuits for
possible troubles or other video "blanking" circuits. Also, so far I am
suspicious of D519? (High speed switching recitfier in that that feeds
an input to the video select chip. I have scoped the outputs of this
chip and they are turning on and off during this....(of course.) This
TV is a 1999 model and is in great shape other than this. I would be
interested in what the service tech told found or what he did, if
anything to fix this???

Thank
Lew