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What's DOS?
Posts: 2
Registered: ‎09-14-2011
Location: TX
Views: 3,181
Message 1 of 3

T400 Screen Issue - Half Dark

I have been having issues with my screen /backlight  in the last month.  I actually took a video of the problem hoping it would give you a better idea of what's going on.

I have a WXGA LED screen 1280x800 w/ camera and keyboard light.  T400 purchased Dec 2009.



- Right side of the screen is visible but a lot darker than the left

- Adjusting brightness does not work on either side when it is like that

- Sometimes screen will flicker ever so lightly

- Sometimes screen will go completely dark, but text is barely visible if you look at point blank range (backlight issue?)

- Closing the screen for sleep mode and then awakening will fix the problem, sometimes for extended periods (hours), sometimes for seconds

- When the screen is working properly, changing brightness works; however adjusting to darkest setting will only yield a darker right side, and no change on the left
- Sensitive to movement; if the screen is working, moving the laptop around or adjusting the screen will cause right side to go dim or all to go dark.


Is the problem the led screen, backlight, connection, motherboard or something else?


Hopefully someone has seen this same problem and can help.  Thanks!


Here is the video for reference.

Former Employee
Posts: 2,437
Registered: ‎04-10-2011
Location: Malaysia
Views: 3,129
Message 2 of 3

Re: T400 Screen Issue - Half Dark

hey dztech,

could be an internal cable issue, in which i would recommend calling the support team via

1-800-426-7378 [Select "Option #1"]
24 hours/day - 7 days/week

While you do that, i would recommend uninstalling the current video driver of your unit, let windows install its generic drivers.

run the same test as you did in the video and see if the result is the same.

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What's DOS?
Posts: 2
Registered: ‎09-14-2011
Location: TX
Views: 3,112
Message 3 of 3

Re: T400 Screen Issue - Half Dark

Yesterday I decided to open up the lcd assembly to examine and copy down the exact part # of my led sub card and lcd screen.  I thought it had to be the sub card or lcd panel. But as i observed b4, the lcd would work fine for hours as long as the laptop was on a stable flat surface, which led me to believe the lcd should be ok.


Anyways, after removing the front and back bezels, I detached and reattached the led sub card.  Then I visually inspected the lcd panel.  Everything looked fine.


I turned it on and lo and behold, the screen has been working perfectly for the last 24 hrs.  No dimness, no blackout.


My conclusion is that perhaps one or both connections on the led sub card were not seated properly.  Anyways, I will continue to observe and hopefully, everything is fine now, knock on wood.

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