03-03-2013 06:18 PM
First it was cracks on the lid, then there was a stuck battery latch, then it stopped booting, and now there is no screen backlight. Oh Lenovo, what have you been doing to the beloved Thinkpad brand? :-(
It works with an external display, but that is not really the point of a laptop computer.
I have seen this thread ("T420 no backlight bad fuse?") here and this thread ("T420s with broken backlight - replace the whole panel?") in thinkpad.com forums and I am somewhat confused as on how to proceed from here. I would like to avoid an expensive repair if this is something I could fix myself. I am not entirely sure it is a blown fuse issue, because the no backlight problem occured a few times (it would not work sometimes on boot, sometimes it would) before it the backlight stopped working entirely. It possibly is a loose contact somewhere. Hopefully. I suppose the hardware manual could help, but I am not sure what is it that I should look for.
Would you folks have any advice for me?
Solved! Go to Solution.
06-26-2013 04:27 AM
06-26-2013 06:16 PM - edited 06-26-2013 06:18 PM
There is also a switch that senses that the lid is closed. I have seen one fail. On that machine, I could unplug the cable on the left side that has the connectors that control the LEDs on the control board. The backlight would magically light.
06-27-2013 12:28 AM
On my machine it turned out that the problem was being caused by the graphics driver. We uninstalled and reinstalled a newer one and it now works fine.
There were a couple of expert opinions;
1. it's your inverter (hardware problem)-based on the fact that the screen brightness faded suddenly (but didin't disappear) and that the screen was not bright on a reboot from before the login screen
2. It's a software problem- for which the solution was back everything up and do a reinstall
Was very glad that the guy who had seen exactly this problem before spotted it before either solution a or solution b happened.