I have a LG 47ln5700 smart tv. The screen goes black but the sound still works. I replaced the LED strips and the tv worked for about 4 hours and then the same thing happened. Any suggestions?

Hello !! first of all check for bad connection on the led strips if all connection ok , test the single led one by one , at the end Do not Hesitate replace the leds strips . Because problem could happen after heating .

Replace the jack wires going to the LED strips. Or look for the one bad jack wire going to the LED's and fix it. Use a volt meter on ohms to find the bad wire.

Defective LED back lights strips, need change them all.

Clean with eraser LVDS cable and fix correctly if not working replace it

Chances are you have bad lamps in the panel...you will need to take the front cover off and get under the panel and test them and see if some are bad, if they are replace the strip...good luck as its not all that easy to get the panel off and back on without damaging it, use extreme care handling it or once you get the lamps working the panel can be damaged and then it has to be recycled as it can't be fixed

Main digital board fault. Check and replace it. If you wish to get more details visit the site linked here. http://electronicshelponline.blogspot.com/

You have wasted your time and money. The LED power supply and LED strips are only the backlighting. The only thing that might fix is a situation where you have a blank screen with the sound working.

If you don't know what you're doing, DON'T OPEN THE TV UP TO FIX IT, THERE ARE HAZARDOUS VOLTAGES ON THE POWER SUPPLY BOARD, EVEN WEEKS AFTER THE TV IS UNPLUGGED!

If you don't know how to do it yourself, find some local Electronic repair shops, get quotes, try to find reviews on the shops.

If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
http://electrotechnician.blogspot.com/

If it was the LEDs, then you should still have some working. My first thought would be the LED driver circuits.

Best of luck.

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