English Community

ThinkPad NotebooksThinkPad: T400 / T500 and newer T series Laptops
All Forum Topics
Options

2 Posts

07-01-2011

USA

20 Signins

26 Page Views

  • Posts: 2
  • Registered: ‎07-01-2011
  • Location: USA
  • Views: 26
  • Message 1 of 9

Thinkpad T400 Backlight Issue

2011-07-01, 19:15 PM

Now, I suspect that the inverters are fine and I'm wondering about the LCD switch or LCD cable. I suppose I could just buy a cable, but before that, I wanted to take a step back and try to figure out if I'm overlooking anything. I've not been able to find a picture or location of the t400 lcd switch in either the lenovo hardware manual for the t400 or elsewhere online.

Hi,

I've got a thinkpad t400 with CCFL backlight. I recently replaced a bad LCD (the backlight was working at the time) with a new one. However, while the new screen works, it's backlight did not. I ordered a new inverter and plugged that in - still didn't work. I grabbed the old screen's backlight and tried it with both inverters - did not come on. I then grabbed another laptop I have and plugged in the old screen's backlight - it came on. Plugged in the new screen's backlight (while lcd was still plugged into the thinkpad), it's backlight came on.

So, I know both backlights are fine, and suspected I just had a crappy inverter. I got a replacement new inverter and it still doesn't work. Tried new lcd and old backlight with all three again, no dice. Backlights still turn on when connected to spare laptop. So I now suspect the inverters are fine. I noticed that the laptop no longer goes to sleep or hibernation when the lid is closed. I changed the power settings so that it should sleep or hibernate, tried each power mode and it still refuses to do so.

 

So I think the issue is with the switch that detects when the lid is closed. Does anyone know where this switch is located on the t400?

Reply
Options

5 Posts

06-08-2008

NC, USA

6 Signins

51 Page Views

  • Posts: 5
  • Registered: ‎06-08-2008
  • Location: NC, USA
  • Views: 51
  • Message 2 of 9

Re: Thinkpad T400 Backlight Issue

2011-10-03, 19:48 PM

Did you ever figure your problem out.  I have the exact same issue...  Thank!

Reply
Options

2 Posts

12-30-2011

Australia

6 Signins

26 Page Views

  • Posts: 2
  • Registered: ‎12-30-2011
  • Location: Australia
  • Views: 26
  • Message 3 of 9

Re: Thinkpad T400 Backlight Issue

2011-12-30, 15:55 PM

My T400 just got same problem. LCD is blank, only faint Lenovo logo visible during bootup, then hardly can see anything on LCD screen. No LED indicator is on either, except the wireless LED. Power setting not working either, so the close lid power function is not working as it supposes to.

 

Anyone has any idea what happen? and how to repair it?

 

Thanks

Reply
Options

10711 Posts

01-02-2010

US

39401 Signins

409037 Page Views

  • Posts: 10711
  • Registered: ‎01-02-2010
  • Location: US
  • Views: 409037
  • Message 4 of 9

Re: Thinkpad T400 Backlight Issue

2011-12-30, 22:07 PM
If the backlight does not come on AND the indicators on the screen (power, battery, etc) don't come on, my guess is that 2 fuses on the motherboard are blown. Lenovo does not do that sort of repair, other than replacing the board.

Rich


To help with forum searches, check this out: https:/forums.lenovo.com/t5/Welcome-FAQs/Using-Browser-Search-to-find-your-answers-in-Lenovo-and-Moto-Community/m-p/5016916

I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
Reply
Options

2 Posts

02-09-2014

United States

2 Signins

9 Page Views

  • Posts: 2
  • Registered: ‎02-09-2014
  • Location: United States
  • Views: 9
  • Message 5 of 9

Re: Thinkpad T400 Backlight Issue

2014-02-09, 2:05 AM

Black  Screen (faintly visible with a bright light)  

Showing a little pink and small flicker just before if went dark.

Works with external screen.

Green indicators below are working.

 

The oddest this is that ir will show a windows screen at startup about 2 seconds into arriving at desktop.  It has also appeared briefly when I returned after it was idle for a while.

 

Is this something that can be fixed?  

 

Most of the posts said no green indicators.  Is this still a problem on the motherboard   -- a I read thoe pots, therefore one that can't be fixed at a reasonable rate????

 

Thanks

Reply
Options

2 Posts

02-09-2014

United States

2 Signins

9 Page Views

  • Posts: 2
  • Registered: ‎02-09-2014
  • Location: United States
  • Views: 9
  • Message 6 of 9

Re: Thinkpad T400 Backlight Issue

2014-02-09, 16:02 PM

Windows XP on the laptop.

Reply
Options

10711 Posts

01-02-2010

US

39401 Signins

409037 Page Views

  • Posts: 10711
  • Registered: ‎01-02-2010
  • Location: US
  • Views: 409037
  • Message 7 of 9

Re: Thinkpad T400 Backlight Issue

2014-02-09, 17:10 PM
to enorth - you have a blown bulb, and need a new panel. The pink flicker is the clue.

Rich


To help with forum searches, check this out: https:/forums.lenovo.com/t5/Welcome-FAQs/Using-Browser-Search-to-find-your-answers-in-Lenovo-and-Moto-Community/m-p/5016916

I do not respond to requests for private, one-on-one help. Your questions should be posted in the appropriate forum where they may help others as well.

If a response answers your question, please mark it as the accepted solution.

I am not an employee or agent of Lenovo.
Reply
Options

3 Posts

09-20-2017

PL

4 Signins

119 Page Views

  • Posts: 3
  • Registered: ‎09-20-2017
  • Location: PL
  • Views: 119
  • Message 8 of 9

Re: Thinkpad T400 Backlight Issue

2017-09-20, 17:23 PM

Hi there. I am aware it's been a long long time since the issue happened, but have you had any luck fixing it? I have the exactly same issue with my brother-in-law T400. He cracked the screen so I replaced it, and after replacing there is no backlight. I ordered new inverter but no luck as well. Please tell me this is no fuse and it can be fixed easily :(.

Reply
Options

1 Posts

11-20-2017

US

6 Signins

46 Page Views

  • Posts: 1
  • Registered: ‎11-20-2017
  • Location: US
  • Views: 46
  • Message 9 of 9

Re: Thinkpad T400 Backlight Issue

2018-02-19, 16:42 PM

wrote:
If the backlight does not come on AND the indicators on the screen (power, battery, etc) don't come on, my guess is that 2 fuses on the motherboard are blown. Lenovo does not do that sort of repair, other than replacing the board.

This is the exact issue going on with the T400 I'm working on. The LCD is very faint, barely able to see the ThinkPad logo as it boots up, and the indicator LEDs on the the display assembly are not lighting up. You mentioned that it might be 2 fuses on the motherboard. What other possible parts could cause this issue, how likely is it that these are the faulty parts, and are they something replaceable?

Reply
Forum Home

Community Guidelines

Please review our Guidelines before posting.

Learn More

Check out current deals!

Go Shop
X

Save