(TV - LCD) Samsung T220M - power supply IP-54135 (A/B) issue

Hi. I'm new to EDABoard, but have a question already.

I've been asked to repair a Samsung T220M TV/Monitor. But after some inspection, I can't find any component worth of replacing.
The symptom is backlight going off after about 2.5 seconds after being turned on (LCD is still working, but w/o backlight). I've tested what I could and found nothing wrong, but tested via scrap and found that the output voltage that goes to the fluorescent lamps keeps decreasing after the power-up.
Usually a capacitor issue, but the ones I've replaced (3x 1000uF 25V and 2x 1000uF 10V) ended in no result and the others, which I can't find replacement where I'm currently living, aren't stuffed or even seem to be nearly. Of course, the issue is most likely due to the capacitors, but could someone, please, share some light?
The power supply board is stamped as IP-54135A, but after searching the internet, the "A" is quite different, and the IP-54135B looks the same as the one in question.

When power is supplied, a humming noise higher than 15kHz can be heard coming from the region one of the 3.3uF 50V, 47uF 25V, 680 25V, 330 25V capacitors (which would mean problem) or the Trafo, but that's quite unlikely. The noise intensity gets higher after the symptom shows off.
Well, can't think of anything else right now, so I'll leave this question. Definitely need help from someone experienced.

Glad for your attention.

NM. I've searched the board again having in mind that every componente was in perfect shape and finally found the issue in the wiring to the upper backlight. It's working good now.

Do you have schematic of the section of fluorescent voltage regulation?

Maximiano said:

NM. I've searched the board again having in mind that every componente was in perfect shape and finally found the issue in the wiring to the upper backlight. It's working good now.

Click to expand...

burt007 said:

Do you have schematic of the section of fluorescent voltage regulation?

Click to expand...

I'm sorry, I don't. Just searched through the power supply board over and over until accepting that the issue should be somewhere else. Just then realized a possible short-circuit when testing with most parts disassembled. All I did was redo the wiring and insulate some contacts and terminals.