Dim Screen on Laptop

dballs · December 10, 2019

I have a fleet of a dozen or so Lenovo T540p laptops. One has an issue with it's screen being incredibly dim from power up/splash screen/boot screen, on. So dim I cannot see the screen unless the lights are out or I get real close.

I have replaced the screen entirely and the cable connecting the screen to the mobo
The FN brightness buttons do nothing.
I have pulled the battery and CMOS battery to try and reset the bios completely.
I can plug in an external screen with VGA and it works fine. I have gone in and reset all BIOS settings to factory.

I also have another of the same model I can pull parts from (hence were I got the spare screen and cable from). This has nothing to do with Windows settings.

Any thoughts? Is the mobo just toast? When I plug in an external screen via VGA it works great so I'd hate to trash a working computer.

Thanks!

kelvinhall05 · December 10, 2019

Very strange. I would assume that since a replacement display didn't fix the issue there's something wrong with the mobo.

Have you closely looked at the pins for the screen cable? Both on the cable and on the motherboard. It's possible there's just a bent pin or something.

dballs · December 16, 2019

Just checked. No bent pins...

This is strange. I have been a tech coordinator here for 8 years and have seen/worked on 1000's of laptops. I have never encountered this issue before. Like I said the computer works find when an external screen is plugged in and I would hate to trash a working computer. Maybe it is just a desktop now that will need to live connected to an external screen. lol.