Screen is dark and pixalated

You have a bunch of burned out LED buttons in the LED strips that light the panel, new strips will fix the issue. You didn't give the model so I can't help with part numbers but go to shopjimmy.com and put the number in there in search and you will find the parts, they generally run around $75 for a 55" set with shipping plus your local sales tax. Watch several youtube vids on changing them, it's a time consuming job but not hard to do just handle the panel with extreme care as it can be damaged then the set is junk. Once you get it fixed do a software update to extend the life of the new strips.

In the dark with the set on do you see light if you look through the vent holes in the back?

Sounds like the backlight has failed.

Samsung LCD TV with no video and high pitched sound - Digital TV ...

www.tomsguide.com/forum/54120-4-samsung-video-high-pitched-sound

Jan 7, 2010 - 26 posts - ‎15 authors
Hi, I have a Samsung LN40A550 LCD TV which I have had for just over a year. ... I was watching TV yesterday and all of a sudden the picture went all. ... started makinga very high pitched buzzing sound with no picuture coming on. We did have a bunch of green vertical lines, but now just a black screen.

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What is the last thing that happened before you noticed there was a problem?

If still under warranty, I would suggest going that way as this is a bad matrix driver....

I had the same problem a few months after buying the TV, called LG and they sent a tech to replace two boards in the tv. No further problems since.

From what you are describing, it sounds like the inverter board is failing. This board sits under the LCD screen and is responsible for taking the DC voltage from the battery and AC adapter and converting that voltage to high voltage AC power for the backlight lamp that sits inside the lcd screen. Without that high voltage the screen goes dark. Most inverters do not fail right away, there are voltage fall offs etc. Inverters are approx. 15-20 bucks on ebay, for most laptops, they can be changed out simply by removing the bezel around the screen, unplugging the two connectors on the inverter and changing it out. In most cases except Dell, the inverter is just sitting in there and is not held in by screws.

sounds like your monitor is shot or one of the connections in the back hope this helps regards Jim

Make sure that the color control level is set to the default or 50% to start with. This should be in the Video menu.

The colour for the tuner and for the encoded base-band video uses a circuit area called the colour demodulator. It is possible that this cirucuit area has failed and needs servicing.

Jerry G.