Lenovo T420 - LCD displaying nothing (Except backlight), external outputs work.

[Blue House Computer Help]

I need a quick hand....

I have a Lenovo T420 where the LCD is displaying nothing (Except the backlight), but the external VGA & DP outputs work fine. I changed the LCD screen and the display cable, but it's still the same.

Tell me there's something else I can do besides scrapping it or replacing the mobo??

 

[NviGate Systems]

You likely have a failed mainboard. In reality, it's probably a blown fuse or other component. However, that's expensive to diagnose and repair.

You could see if you can find a service manual or schematic, it might show you test points for some of the more common failure points.

Failing that, replace the board. Granted the T420 is getting long in the tooth, so it might be time for a new system.

 

[Larry Sabo]

You could see if you can find a service manual or schematic, it might show you test points for some of the more common failure points.

Here's one. Good luck troubleshooting the problem though! If it has backlight, I doubt there's a fuse gone (although there are a couple).

 

[britechguy]

Shades of my ongoing Dell G15 issue. I truly wish you best of luck and hope that you do find a solution.

The symptoms are exactly the same, and I've given up. I don't have the diagnostic equipment (nor experience, even if I suddenly had access to it) to address something at the motherboard level.

 

[Blue House Computer Help]

So... given the age of the computer, he opted not to go with a motherboard replacement. But I may get some work transfering his files to a new laptop, so that would be good too.

Thanks for your help guys.