Screen goes blank randomly during use while VGA signal present LED on front panel remains green. Possible backlight issue.

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Sounds like the main board as it has all control and signal processing on it.

it is possible a VGA card damage.

Ok, another words, monitor powers up for few seconds and shuts down by itself. If green LED on the front panel turns off as well or stays on?
If stays on, then inverter turns into protection mode because of old backlight lamps.
If it turns off in same time with an image on the screen, then there are some bad electrolytic capacitors in the power supply.

power control chip of the VGA input screen is not controling the input settings

power pack has issues could be a chip on the power pack or some capacitors on the power pack. the power pack supplies power to the inverter.

I too have a dual monitor Samsung SyncMaster 204 setup. My monitors started flickering, then a week later had turn on problems like your describe. I found a fix on this fixya website and followed the fairly techie suggestion. It worked. I wrote up a .pdf set of instructions so others might also benefit. Hope this helps. Doug

check if your signal cable is properly connected to your system unit and make sure that non of the pins of your signal cable is broken.if any of the pins are broken,try and change the whole signal cable and re-connect it again
after following the above instruction,reboot your computer
thank you for contacting as with your problems,you are always welcomed

You could check the VGA cable from the replicator to the monitor, but a problem with that will usually cause a "NO SIGNAL" message to appear. So your issue seems to lie within the monitor. It could be that the backlight has quit. That can be determined by booting the laptop and connecting it to the replicator, or perhaps to the monitor directly, and observe the screen using a good flashlight, place the flashlight flush on the screen in an area where you would expect to see an icon or some recognizable image. Look closely to see if the image can be seen. If the image is there, then the screen is ok but the backlight is out. The problem is usually the inverter. A reputable shop might be able to replace that.

It sounds to me that the monitors power supply is dying. I would replace it with a different monitor as soon as possible. I would consider this a dangerous situation, and a possible fire hazard.

Thanks for using FixYa,

Hope this helps,

Eric