Backlight goes out when unplugged

[Do It All Computers]

Working on an issue that this lady has had for the past year. The backlight goes off when the laptop is on battery power. Asus x555L, working perfectly except for that issue.

Things tried:

Replaced Battery
Brightening the screen when unplugged.
Updated Bios.

Next up: screen replacement?

Stumped

 

[NJW]

The backlight goes off when the laptop is on battery power. Asus x555L, working perfectly except for that issue.

Known issue with the display panel – power supply choke out of tolerance, from memory – but changing the panel won't fix it. There is a fix, if you're prepared to do component-level repair on the display; I'll try to find details and add them here.

Edit to add: see Badcaps forum (several threads, but this takes you straight to the details): https://badcaps.net/forum/showthread.php?t=68578&page=2

The choke in question is not too small and can be replaced without exotic soldering facilities.

 

[sapphirescales]

Update the graphics driver. I know it sounds weird, but trust me, I've had some weird issues where the screen wouldn't light up due to an improper driver. You can also try to manually adjust the screen brightness using the hotkeys on the keyboard. If it works when you adjust the brightness levels with the hotkeys, that could be a driver related issue too.

 

[backwoodsman]

First you'd want to boot from a Linux disk (or anything other than the installed Windows) to be sure of whether it's a hardware or software problem. Then you'll know which direction to go.

 

[Do It All Computers]

Update the graphics driver. I know it sounds weird, but trust me, I've had some weird issues where the screen wouldn't light up due to an improper driver. You can also try to manually adjust the screen brightness using the hotkeys on the keyboard. If it works when you adjust the brightness levels with the hotkeys, that could be a driver related issue too.

Have tried this along with reinstalling windows. This is definitely hardware as it will do the same on boot up and booting into WinPE.

 

[Do It All Computers]

Known issue with the display panel – power supply choke out of tolerance, from memory – but changing the panel won't fix it. There is a fix, if you're prepared to do component-level repair on the display; I'll try to find details and add them here.

Edit to add: see Badcaps forum (several threads, but this takes you straight to the details): https://badcaps.net/forum/showthread.php?t=68578&page=2

The choke in question is not too small and can be replaced without exotic soldering facilities.

Looked at the tread, but haven't read it all. Thanx!

 

[NJW]

I'd recommend not swapping the display panel – the issue seems to be the panel specification, which must be borderline with a new computer. Eventually, it can't power the backlight with the voltage that the X555 main board supplies to the panel when on battery power. You may be lucky with a replacement panel and the backlight will work, but fail again with similar symptoms within a few months.

I had one of these (customer machine) a couple of years ago and tried everything but swapping that inductor – reinstall Windows, dozens of different graphics drivers, power settings, replacement battery, Linux test install and probably a few other fixes from the Internet. A replacement panel was on long leadtime at the time (fortunately, as it turns out). Changed the choke with a component from a salvage panel and it's still working fine.

I suppose it's possible that something on the main board drifts out of spec over time. I don't know if/how much the battery voltage to the panel changes from new.