Ive got a LG 55" LED tv model #55LA6200 it will turn on and show the LG screen then goes black after a few seconds. Audio works and i can see the screen with flashlight which part do i need.

Defective LED back lights strips, need change them all.

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

Test your panel lamp voltage lines and see if they drop off when the screen goes black

Sounds like the backlight has failed.

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://electronicshelponline.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.

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/
http://electronicshelponline.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.

LG LED TV has no picture (black screen) but still sound ...

www.tomsguide.com/answers/.../led-picture-black-screen-sound-fixed.ht...

7 days ago - My 32' LG LED TV has suddenly lost picture! The sound is all right but theScreen is pitch black. After switching it on the picture flashes for a second and thenthe ... LG LED TV has no picture (black screen) but still sound - can it be fixed? Tags: ... a touch on the screen reveals nothing so it's not the back light.

Monitor going black after 2 seconds [Solved] - CCM.net

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Oct 9, 2012 - Brightness goes down, display draws less juice, and you can at least use .... it's the LCD's Inverter ... you have to replace it for it to go back to ... If the screen is turning off every two seconds or so and then it comes ... i turn my tv on it comes right on, but then after a few minutes turns off, .... Digital Trends for LG. No display in monitor
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