There are 2 power supplies. One is always on & supplies
the micro & on/off relay ( if it has one.). Second one supplies
B+ for horz/HV. Its on/off is via a relay or other method.
You will need a schematic for at least the power supplies
to check them & see if one isnt working.
Use care changing the IC's the board is double sided & you will
probably lift some top etch. If you have very small dikes
you can try nipping off the IC pins & saving the etch. Otherwise
you will need jumpers.
We were a authorized Sony dealer / warranty station at that time.
Never seen a bulletin on the problem & Sony TA changed the subject !
It was common, I had the 30" & went through 3 sets in abt 5 yrs.
Shame of it is the 30 & 34" widescreens were the best CRT sets
ever made pix wise.
good luck Zeno
LFOD !