Lg 47ln5700 Tv lost backlight with sound still working. Did the flashlight test and the picture was dim but there. I thought replacing the power supply LED board would fix the problem but problem still persists. Any suggestions?

SOURCE: lg led tv backlight

Fault with its main board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

SOURCE: How do I fix my Samsung 40 LED TV that has sound but no picture?

Samsung 60-Inch 1080p 120Hz Slim Smart LED HDTV ...

? 10:42
www.youtube.com/watch?v=hcVhHU322Gk
May 18, 2015 - Uploaded by Thomas M. Landry
samsung un60h6350 60-inch 1080p 120hz smart led tv,samsung... 120hz smart hdtv,slim led tv,65 inch smart tv deals,samsung 40 led 1080p 120hz ... LCD & LED TV Repair - No Image & Blank Black Screen Flashlight Test ...

SOURCE: When testin a power supply or led board on tv do i test dc or ac with multimeter?

Your power supply board is working if you get audio and imgaes.

You test AC only the AC side of the transformer before the Rectifier Diodes. Everything after the Diodes will be in DC.

did you get to see any spec of backlight as shown in
LCD LED TV Repair No Image Blank Black Screen Flashlight Test How to Fix...

SOURCE: My tv has sound but no picture. Does the power supply board include the led driver?

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electro-medical.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

SOURCE: Model 50LA6970-UE LED. Has sound, but why no picture?

Hi Paul i have the same problem how do you fix it?