LCD hissing repair

[Kralik]

Hi,
I started using my old (4:3 ratio)Fujitsu Siemens lcd as my secondary monitor. it runs perfecly, but the hissing sound drives me crazy. The monitor is pretty old so i dont know if some of the caps are damaged or they dried out (it might me ) or the sound is making the CCFL tube. The sound starts right after i turn the lcd on, even before the image comes on, but i guess the CCFL tubes must be already on. I read that the tubes start making noise when they are set on low brightness (bcs PWM) but after i turn the brightness down, it starts making different noise(without effect on the first one)
Do you know whats causing the sound? or is it just common problem with older models?
Thanks very much,
kralik

[coppercone2]

i had a shitty TV that would be unusable at low brightnesses because of noise

[Kralik]

yeah, but even on high brightness the noise is the same and it drives me crazy, only if i turn down the brightness the second noise starts... can there be something to repair or its just a deal with old models of monitors?
thanks

[Dacke]

I've worked on and repaired more TVs and monitors than I can count and the few times I've heard hissing it's almost always been a bad CCFL that's arcing within the tube or there is a bad connection with one of the CCFL sockets and it is arcing there or onto the metal lcd frame.  If you have good hearing and are in a quiet place,  you can put your ears up to differrent parts of the monitor and usually pinpoint what area it's coming from.  You may also smell ozone there.  The area where it is occurring will generally look black/burnt or even rusted (ozone accelerates corrosion).

[Armadillo]

Since it's old;

The first step would be;

Open up and blow all the dust away with compressed air.

that's the first step, before even delving into electronics.