Monitor backlight turning off when signal cable plugged in
I have recently bought a faulty Samsung Syncmaster F2380 monitor in hope of fixing it and using it for personal purposes. The device used to work for a few seconds before turning off the backlight until pressing the power button. After opening up the device I noticed one cable of the CCFL backlight had burnt at the solder point on the CCFL tube. After resoldering the connections to the tubes and checking everything else I reassembled the whole thing back together.
Unfortunately now the monitor turns its backlights off when plugging in a signal cable (e.g. VGA or DVI), but remains on when not plugging one in (except it outputs the expected "Check signal cable" because nothing is plugged it)
I have also checked all capacitors on the main power board, as the CCFL lamps connect directly to it. I do not know how to check whether the CCFL Lamps are working or where the issue lies, but its just strange that the backlights only turn off when plugging in a signal cable. I would get an image for a few seconds, then the backlights would turn off. Perhaps the device turns on additional backlight lamps when it receives a signal?
I will open it up again sometime, and check which lamps actually turn on or not when plugging in a signal cable.
I really dont know what things to check next, so I would really appreciate help on this topic (especially as many others are having this issue as well)