I'm using a Samsung T240HDTV. The screen goes to very dark frequently so that I can hardly see the image, after I turn it on. I guess may be something wrong with the backlight. Can somebody help me out with it? THANK YOU!

You can try a tcon but I think it's going to be a panel issue

There is a very good answer to your monitor issue found here:

http://www.fixya.com/support/t467725-samsung_lcd_monitor_syncmaster_203b

Sounds like your Tcon board is giving issues.

i guess there is some problem with your panel. make sure you show it to the nearest service centre

The LCD can be replace just bring it to the samsung service center to replace new LCD and back to normal images.

have you checked your brightness controls

Have you tested it with an external monitor?

I would say you either have a damaged inverter board or screen baclight lamp. Usually the inverter board fails in one of the following ways:

1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor.
2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor.
3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.

Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.

If the power totally fails (i.e. power is cut off, LEDs turn off, fans stop, ... etc), then this more likely to be because of a short circuit developing in a failing semiconductor component, or a power supply problem.
However, if the laptop is still running & only the display on its LCD is cut off but the laptop itself stays powered on, then your laptop might be experiencing a failing screen inverter board, a failing screen backlight lamp, or a failing LCD screen cable.

TYPICAL INVERTER FAILURE SYMPTOMS

1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor.
2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor.
3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.

Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.

contacted sony and they said they are having same issues with many sony dsc-t1 cameras and they are fixing it for free. just have to pay shipping cost and they repair it for free. something internaly I guess.

get a new tv