Hi Simisker,
Chap in Quuq files suggests check/replace Caps 2465, 2508, 2540 and 2541 (all 100/16)
Good luck - Inverter/tube problems usually cut backlight in seconds, never 30 mins, as CCFL tubes are warm - Chris.
Just realised 'Goes off' might mean 'reverts to standby' - Guess Simisker will clue us.