Can not get the back light to light system is working but backlight is not

Hi Jason,
Generally there are two reasons for no backlight in LED TVs. Either it is the inverter which produces necessary power to drive the backlight stops working or some of the LEDs in the backlight array fail. In some TVs even one failed LED will cause no backlight.

To modern sets, with LED based back-light system, the back light inverter will be a part of the main power supply regulator board. 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.

Most common failures in these LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply C242 470uF 10V, C241 & C242 1000uF 16V, C261 & C319 680uF 35V failed as indicated in the attached picture, replace them at once.

If the power supply board is working then it is back light problem, first do a flash light test. If you can see the image in the flash light test, follow the steps how to test back light voltages: https://how-to-repair.org/repair/lg-tv-repair-manual-pdf/lg-led-tv-no-backlights-32ln5300-32ln5310-32ln5700-voltage-test-troub/2pyuXwNkBMA.html and follow the steps how to repair back light LEDs: https://www.youtube.com/watch?v=_poWTEihIJU Fix Led Backlights for TV or Monitor Lg Led Tv No Backlights 32ln5300 32ln5310 32ln5700 Voltage Test Troub Lg... Fix Led Backlights for TV or Monitor

If pressing of the light bulb icon does not work at relighting the screen the LEDs/back-light may have burnt out. You may have to get the system replaced.

Hi Piergiorgio,

Nothing in the registry or BIOS however, in the Flybook control center, you can manually set your brightness on the system and turn off auto backlight. That way the system will always turn on and your system will always remember the setting of the back light.

Let us know if that helps!

You are lucky it works at all. The system board has been compromised.

If you can see the picture under bright light then suggest you navigate to System->settings->backlight->configure and try to raise the brightness level. Have you tried a hard reset - small slide switch on the bottom edge. If this does not work then the back light or control electronics may well be broken.

Hi,
For latitude systems they have this ambient light sensor. it basically adjusts the brightness of the screen depening on room lighting. try to go to bios by hitting F2 on the dell logo. go to video and try to look for ambient light sensor. however, im not sure if your computer has that feature I have a second option for you though. based on the troubleshooting you've done, it seems that the video back lighting is affected by movement. it would be a good try to reseat the LCD cable. you can use this link to guide you in fixing the computer : http://support.dell.com/support/edocs/systems/latd505/sm/keyboard.htm
all you need to do is to take out the keyboard with 2 screw holding it in place. the LCD cable should then be accessible. it a thick cable that coming out of the Left hinge.

Hope this helps.

thanks.

It is possible that by holding the power button down too long, that you turned off the backlight. When you hold down the power button, a menu eventually comes up with "Backlight Off" highlighted. The easiest way to undo this, is to simply do a soft reset. Or, you can hold down the power button again, and "Backlight On" will be highlighted (if there's enough ambient light you can see this message); just tap it, and the backlight will come on again. Also check out your backlight settings by tapping: [Start][Settings]tab[System][Backlight] the tab [Battery Power] should be highlighted; adjust as desired. Next tap the tab [External Power]; adjust as desired. Finally, tap the tab [Brightness] and make sure the sliders are high enough.