Which model/size, date of manufacture, etc of LG? it may be the logic card.does the tv control menu come up?
It's an LG 42LN5700-UH smart tv 2014. When I turn it on the LG logo flashes for a second then goes black. There is sound and see the back light with a flashlight.
ok, here's a bunch of info:
https://www.lg.com/us/support-product/lg...
things to try:
1- what happens if you hook up a laptop? does it display? (it does have a VGA input?)
2- if you can see the logo and it is nice and bright then the screen is _probably_ OK
3- can you bring up the tv control menu (where you can set Source, Color, etc) and see it? if so, the screen is definitely OK. if not, then it's bad
4- the backlight can actually work but be too dim (worn out). can you run the Brightness up/down?
5- carefully examine ALL circuit boards for blown capacitors. they can bulge out the top, the bottom, or even leak a nasty looking stuff (it will be obvious, do a Google Image search for 'blown capacitors'). Badcaps.net is a great reference for this kind of stuff too
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SOURCE: No picture on mu LG television.
Try the old flashlight test, turn off the lights in the room. Turn on the set and flash a bright flashlight on the screen. Do you see the image or is the screen totally black?? If you see the image, then most likely you have a backlight problem. Verify that you have 24V on the power supply for the inverter
SOURCE: lg 47lk520 reset
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.
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.
The backlighting has failed. If it is an older fluorescent bulb type you most likely need an inverter board.
Do flashlight test to see if y0ou can see an image - if so replace the inverter board that powers backlights. If no image then go for the main board.
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