Same problem picture turns blk but there is sound

Black square on the screen Vizio Gallevia 47" 1080p - Fixya

www.fixya.com/support/t355299-black_square_screen_vizio_gallevia_47

Jan 16, 2008 - Black square sized app. 10"x10" pops up on the bottom right corner of the screen and won't go away. .... Model 42LG70. Why is nothing on screen except for horizontal green and pink pixel line? I am looking at replacing the ...

bad screens display vertical lines with a white background ...

https://www.ifixit.com/.../bad+screens+display+vertical+lines+with+...

iFixitJun 17, 2014 - I am now replacing a screen on a different G2 and I am on the secondscreen. ... A touchscreen smartphone made by LG Released: 09/2013 Model: VS980..... on the rigth side, from the top to the botton has 6/7 black lines.Missing: 42lg70 ‎pixel

Broken LG LCD TV Capacitor Black Screen My Wont Turn ...

? 6:27
https://www.youtube.com/watch?v=EbGiXqBAvvo
Aug 25, 2010 - Uploaded by FixItUrselfDummy
Broken LG LCD TV Capacitor Black Screen My Wont Turn On ...How I fixed my LG TV, Won't turn on or show picture Model: LG42LC7D ...Missing: horizontal ‎pink ‎pixel ‎line

picture board

Check the button for picture size and adjust accordingly.

have the mainboard checked...it may be that something is malfunctioning when cold that corrects when components are heated after some period of use. Sounds like a component error.
The standard avice with FP TVs is to reset to factory default and if that does not clear the problem you have to assume that a hardware fault is a possibility. In that case most folk would contact a technician for assistance
Or you could leave it alone if it does not get worse

Did you check trouble shooting section in manual? Is your TV hooked up to a home theater system? Then check power source to TV. If ok , then I would suspect the lamp blew out.

Sounds like main digital board fault. Contact the authorized service center for LG.
Gopakumar Gopalan Google

you may have a backlight problem. To verify this, dim the lights in the room. Turn on the set and shine a bright flashlight on the screen. If you see a faint picture, you have a backlight fault.

The power source has failed - the sound is the source that autooscillates because even its protections have been damaged and are no longer capable of safely shut it down.
It's a big failure so call a repairman, ther's nothing more you can do.

Go to menu and Reset all Settings

If you are using a set top box this might be caused by turnig the box on at the same tie as you turn the tv on or slightly after you turn the tv on.  If you are using compnent or HDMI inputs the set needs to see the signal as it is turned on to know what formt the signal is in. 

I’m happy to help further over the phone at https://www.6ya.com/expert/dewayne_4a10eab6caecdb92