There are 2 types of psu which can be fitted in this set, one is a 17PW26 and the set will have a separate inverter, and the other is a 17IPS10-3, which has an onboard inverter. If it is the former then check the horizontally mounted UF5402 diode near the centre of the board for s/c. Check to see if the set will switch on with the inverter disonnected. If it is the latter replace the two blue 5pF/3kv disc ceramics in the inverter outputs (normally this results in a flash of backlight but the set comes out of standby ok, so less likely). Let me know what PSU is used, I may have a new one in stock. I need the 8 number part code from the white paper label too.
Main pcb faults are rare but can happen of course.
regards
Ken