cancel
Showing results for 
Search instead for 
Did you mean: 
Reply
weethomas
Paper Tape
Posts: 2
Registered: ‎07-01-2011
Location: USA
Views: 3,963
Message 1 of 9

Thinkpad T400 Backlight Issue

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?

pjusken
Paper Tape
Posts: 5
Registered: ‎06-08-2008
Location: NC, USA
Views: 3,816
Message 2 of 9

Re: Thinkpad T400 Backlight Issue

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

Highlighted
jack135
Paper Tape
Posts: 2
Registered: ‎12-30-2011
Location: Australia
Views: 3,719
Message 3 of 9

Re: Thinkpad T400 Backlight Issue

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

Community SeniorMod
Community SeniorMod
Posts: 10,054
Registered: ‎01-01-2010
Location: US
Views: 3,708
Message 4 of 9

Re: Thinkpad T400 Backlight Issue

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


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.
enorth
What's DOS?
Posts: 2
Registered: ‎02-08-2014
Location: United States
Views: 3,170
Message 5 of 9

Re: Thinkpad T400 Backlight Issue

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

enorth
What's DOS?
Posts: 2
Registered: ‎02-08-2014
Location: United States
Views: 3,149
Message 6 of 9

Re: Thinkpad T400 Backlight Issue

Windows XP on the laptop.

Community SeniorMod
Community SeniorMod
Posts: 10,054
Registered: ‎01-01-2010
Location: US
Views: 3,137
Message 7 of 9

Re: Thinkpad T400 Backlight Issue

to enorth - you have a blown bulb, and need a new panel. The pink flicker is the clue.

Rich


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.
Draccoz
Paper Tape
Posts: 3
Registered: ‎09-20-2017
Location: PL
Views: 1,903
Message 8 of 9

Re: Thinkpad T400 Backlight Issue

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 Smiley Sad.

alex473x
Paper Tape
Posts: 1
Registered: ‎11-20-2017
Location: US
Views: 1,612
Message 9 of 9

Re: Thinkpad T400 Backlight Issue


@richkwrote:
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?

Check out current deals!


Shop current deals

Top Kudoed Authors