LG tv model 47LK520 has audio but no picture screen is grey. what is the problem?

LG 42LS5700 - LG.com

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LG ElectronicsTV/Audio/Video; TVs; 42LS5700 ... TV Support Landing Page - HDTV/Netcast/webOS 1.0/webOS 2.0 ... Adjusting Picture Settings - webOS 2.0 Video ... quality and convenience of complimentary shipping when buying directly from LG.com. ... Curved TVs · 22 Inch to 29 Inch Class TVs · 32 Inch to 39 Inch Class TVs · 40 Inch ...

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Amazon.com, Inc.LG 42LS5700 42-Inch 1080p 120Hz LED-LCD HDTV with Smart TV (2012 Model). byLG. Size: 42-Inch ..... images are nice and crisp when viewing HD content.

Widescreen TV Black Screen - Repair LCD LED PLASMA ...

? 3:41
https://www.youtube.com/watch?v=RbZncfiOXQA
Jul 13, 2011 - Uploaded by FixItUrselfDummy
Fix your tv with black screen blinking light, popping sound noise. ... Watch QueueQueue ... TV Black Screen - Repair LCD LED PLASMA - Problems SONY LG .... I have a 60 inch samsung DPL tv how can I stop the humming or ... What do I do if my tvturns on but its just a black screen so sound no picture?.

T'Con board fault. Check and replace it. If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
Faults & possible causes to LCD screen are given with illustrations. You can get an idea about the fault to an extent.

Check all the capacitors in the power supply circuit. Replace all those that a bulging.
If still not coming on may need the MAIN PCB part# EBT61542106
This is for model: 47LK520UA AUSYLFR...So GO TO THIS WEB SITE:https://www.encompassparts.com/search/
& ENTER your COMPLETE model#

The back lights in your tv are not working. Please consult someone qualified to repair your set.

tried first to disconnect the supply connector going to the inverter board for back light just to ensure if their is no shorted component here. and then turn the power on again if the light stay then the inverter board was the cause why won't power on. by the way did you make a voltage checking at the power supply board does it have correct output voltages 5v,12-16v and the 24v.

Hi, That sounds like an issue with the board in the tv, can't say I've seen it happen with that model yet but I have with last years models. If it's too late to return it to the store where you bought it I'd suggest seeing if they'd exchange it for you if not talk to LG.

The display panel is bad, not worth to repair.

Our same TV is doing the same thing! Think solution is NOT to buy LG products if it has built in redundancy software. What a waste of money!!

Never had that model but had other similar models do that when dust shorted out the High Voltage section.
I suggest clean it out with a gentle vacuum and an upholstery attachment. First check to see if set is under warranty.
Unless you are checked-out with high voltages suggest have a qualified tech test and do this for you.