LG LCD Monitor Inverter Issue

[FercHeliX]

I have a LG L1510S LCD Monitor that has an issue with starting backlight
the problem is that the backlights start for a second and turn off one second after, the lamps are ok, I tested the lamp with another power board and they were fine, I changed all the electrolytic caps on the output line of the board ... but the problem remained. there are some MKT caps, one in the ac input line, 275 ac 330nf, and two on inverter side, one on each lamp circuit, 180nf 100v, each ... i read on a russian forum that they had the same problem and they changed the 180nf caps and a transistor next to it, and the problem solved, but the transistor on their board was a different one and had a burn mark under it, ... but mine is fine visually, does anyone have any opinion on this case ?! ... there's also a hissing sound when the boardtries to start the lamps, what component can make such a hissing noise ?! is it MKT caps or the 400v input cap ? or can it be the emi filter (a choke) ?!?!

- thanks

 

[Vesuvius]

You can easily test the caps so do that.

Here's a trick you can use to find the bad component......
It sounds like a component is quickly overheating then shutting down.

Use Alcohol and wet the board in small squareish places.
Turn it on and watch the alcohol.
You will see the alcohol evaporate extremely fast on the component that is hottest and probably shorted.

You could also use a thermal camera if you have one.

Last thing.....a picture is worth 1000 words. Post a good, hi res close up of the board.