47" LG lcd have sound picture goes &have vertical & horizontal lines of different colours ..Some times works fine ?????

SOURCE: No picture after 20 mins on LG LCD Tv

i have a 32" lg hd flat screen an it now does the same thing i got it on boxing day an its not even 5 months old

SOURCE: LG RZ-42PX11 42

Common problem. See this site -

http://www.forums.hcsd.com.au/Blah.pl?v-print/m-1175589480/

SOURCE: multi coloured vertical stripes on plasma screen

With half of the screen working, and with a Plasma tv. I will look at the driver board as being bad. Take the back cover off, the driver pcb will be at the top or bottom of the set. They are only about 2 inches tall and will cover most of the lenth of the set (2 boards that run end to end). The board that is on the side of the tv that is bad is the bad board. Replace that board or have a tech replace it.

SOURCE: "47 LG LCD TV automatically turns off by itself"

Your Power Board is going bad. I think this set has a one year warranty on parts.

SOURCE: LG LCD TV - Buzzing Sound and Faint Horizontal Lines

From your description, the sound you are hearing is the inverter(s) that drive the back light for the LCD screen/module.
The inverters mounted on the back side (one lower right and one left side) of the LCD screen/module. They are under the sheet metal cover/shields.
The inverters are going out and or the LCD screen/module is going bad too.
That LG TV has only a 1 year on parts and labor from the date of purchase, but you could call LG and ask for their help for such a new TV. They might do it under a warranty, for little or no cost to you.
I hope this information has helped you.
Good Luck.