Lg m4715ccba back light turn off then power down after 05 seconds

Sounds like 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://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/
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

If audio is OK, the backlight inverter is the part should suspected. 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.

You may have power supply problem due to bad caps, shorts circuits in the inverter circuits.
So try it with another PC to make sure it is not the PC problem.
If it is monitor problem, then
If you are going to DIY and have proper tools and know safety precaution then please read on:
Most common failures in the LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply (they should be replaced in a set), blown fuses; poor solder joints, failed inverter circuits (blown fuse, shorted transistors, shorted/open transformers), bad lamps (poor solder connections or worn out lamps). You will need to open it up and inspect the inside, see example of failed monitors to get some ideas what to look for: http://s807.photobucket.com/albums/yy352/budm/
Post back what you see inside so we can guide you further and it will help out other people in the future also.

Basic LCD monitor troubleshooting guide:
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide

http://en.wikipedia.org/wiki/Capacitor_plague

Learn about bad caps: Capacitors kit: http://lcdalternatives.auctivacommerce.com/ he can make you a set of caps for you.

Any luck getting this fixed?Please let me know.Thank You very much!
Tyler

You may have power supply DC filter caps problem or the back light inverter circuits, need to inspect the inside.
Most common failures in the LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply, blown fuses, poor solder joints, failed inverter circuits (blown fuse, shorted transistors, shorted/open transformers), bad lamps (poor solder connections or worn out lamps). You will need to open it up and inspect the inside, see example of failed monitors to get some ideas what to look for: http://s807.photobucket.com/home/budm/allalbums
Post back what you see inside so we can guide you further and it will help out other people in the future also.
http://en.wikipedia.org/wiki/Capacitor_plague
http://www.badcaps.net

First, check the power supply for the backlight. It's usually a 24 volt supply. Look for swollen caps. If that is ok, go to the inverter board and inspect for damage, ohm out the inverter transformers. Last is to test out the lamps seperately with an external inverter. If a lamp goes out this way, it is bad and causing the whole backlight to go out.

The problem can be in 3 places: bad caps in the power supply, shorts circuit in the back light inverter, or bad lamps. You need to open it up and inspect the board for bad caps or burnt parts, take some voltage measurement, you should have 12vdc for the inverter circuits. See example of monitors with bad caps: http://s807.photobucket.com/home/budm/allalbums

HI. I had the same problem with mine. It would flash the screen on for a split second and then turn black, the whole time the power light remained green. Upon opening up the case, I pulled the combo power supply board/inverter board out for inspection. I noticed one of the capacitors had a bulge on top indicating it was bad. It was the the 680uf 25v capacitor. I desoldered it, and soldered in the new one. After hooking everything back up, bingo!! Monitor now works perfectly. I couldn't find an exact match to the capacitance locally, but I had a 1000uf 35v cap in my utility box. It worked fine as a replacement. You can usually go within 30 percent of tolerance and be alright. Just don't go under on capacitance or voltage. I hope this helps.