REPLY tv is a little over a year. just out of warranty of course! how do you change backlight ?

I doubt a main board will correct this, it sounds like LED backlight issues, if you have a multimeter use frame as ground and red lead to backlight B+, you should see 80+ VDC, if you do you have backlight failure and the strips need replacing

Your lcd screen itself or the led-backlight matrix of your lcd screen have this problem ( if there was not worked insite the house or room with wallpaper chipping or new wallpaper?), the answer is to get warranty if it is within the warranty-time in most cases its happens by over 4 a 5 years old SAMSUNG (led backlight matrix) lcd tv's ?? or younger have no heard of this problems by the older lcd ccfl lamp backlight devices.
There is usually no thorough repair option for known as it seems in practice
A great hobby capacitor-rolling option to do ?who should know ? if they look bulged or have leaked on some places, but if there where leaking capacitors there can be damaged print circuit lines on some places on the circuit boards to find if it is find by little brown spots under capacitors.

Beware of people watch out for those who want to empty the rack.

Its maybe a new worldwide problem in much cases and the service oft too. turns out.
To read use a add-on translator and read that its one of an little epidemic question.
Radar Toon onderwerp archief Samsung LCD LE 46M87BD

You were smart to test the image for burned out backlights! :)
Typically, on a screen this size, the backlight inverter is the first place to look.
I found the part number...
27-D026774 Funai TV Module, backlight inverter, PNF10092, I420H1-16A0, 42MF439BF7

You can by it here...

http://www.tristatemodule.com/p-13231-27-d026774-funai-tv-module-backlight-inverter-pnf10092-i420h1-16a0-42mf439bf7.aspx

Had this problem as well. Ran through a laundry list of possible solutions. Finally found that the key is to increase the backlight (Access via [Menu] [Picture] ) to 100% and the noise goes away. If this is bad for the life of the backlight, just pray the backlight burns out inside year 1 while the warranty is still valid!

That is exactly what it is. Mine, as well, (1yr and 4mos old) went out. But my sound, eventually, went out as well. However, I was lucky and had the two year warranty and it was covered. Apparently this is an issue. The fella's that picked up the TV made the remark that "this is another one".

Co-signed. I have the ic200bk stereo dock, and the damn thing died within a year. Of course, Emerson's products are only covered for 90 days. How convenient for them.

Do NOT buy their products. You'll live to regret it.

Your not alone with this problem.
I had to fix mine. The warranty is less than impressive.
The trouble is going to be the Power Supply/Backlight Inverter board.
This is the picture of yours:
This is board # BA71F0F01042. Replacement boards are hard to come by.
Fixing the board like I did seem to be the only option. If you need info on fixing it, let me know.

I have a ln-s4092d that had the same problem after a little more than a year of service. Replacing the main board seemed to fix the problem. But about a year later, the same problem has reappeared. I'm getting ready to replace the main board once again, but I don't really want to do this on an annual basis/

The backlights and their power supply has to be replaced to fix the set. You will have to bring the set in for service to have this done.

Jerry G.

Ditto - JVC KT-SR2000 backlight doesn't work (watched die yesterday), after 2 years, 10 months. Sadly JVC no longer represents quality.  
Note: Original JVC KT-SR2000 was a fire hazard - defective from start - overheated hardly describes it. BestBuy replaced first month.