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VenkatReddy
Fanfold Paper
Posts: 12
Registered: ‎12-10-2009
Location: India
Views: 10,100
Message 1 of 29

T400 motherboard replacement advice needed?

i have a T400 2764cto model thinkpad bought 2 years back with following config

Intel® Core™ 2 Duo Processor P8700 (2.53GHz)
Windows 7 Professional
14.1 WXGA TFT, w/ LED Backlight, Camera
ATI Mobility Radeon 3470 with 256MB
4GB DDR3
UltraNav (TrackPoint and TouchPad) with Fingerprint Reader
Express Card Slot & 7-1 Media Card Reader
250 GB Hard Disk Drive 5400rpm
DVD Recordable 8x Max Dual Layer, Ultrabay Slim (Serial ATA)
Integrated Bluetooth PAN
Intel Wifi Link 5300
9 cell Battery (replaced it in aug 2011)

Suddenly i lost the display (but works with external monitor) when sent to service center they say that motherboard got damaged and need to be replaced and also bluetooth.

NOTE: dont have any other problem other than above ones

SO

is it better to get the motherboard replaced? which they say costs about 500 USD (and 50 USD for bluetooth)

thanks for your thoughts

VenkatReddy
Fanfold Paper
Posts: 12
Registered: ‎12-10-2009
Location: India
Views: 10,063
Message 2 of 29

Re: T400 motherboard replacement advice needed?

updated above...

vnn1206
What's DOS?
Posts: 1
Registered: ‎09-28-2011
Location: abc
Views: 10,036
Message 3 of 29

Re: T400 motherboard replacement advice needed?

May be there are problem with your hight voltage board or lcd panel.

Wendel
802.11n
Posts: 514
Registered: ‎07-03-2009
Location: AD
Views: 10,020
Message 4 of 29

Re: T400 motherboard replacement advice needed?

If the external monitor works and everything else works, how can they say it's the motherboard? If the external monitor didn't work either, then I can see the problem being the graphics chip and you'd need a new MB. I would look from the LCD connection on the MB to the LCD display itself for the problem.

Community SeniorMod
Community SeniorMod
Posts: 10,174
Registered: ‎01-01-2010
Location: US
Views: 10,011
Message 5 of 29

Re: T400 motherboard replacement advice needed?

The graphics chip has 2 separate outputs - one for the LCD and one for external.  Also, there is a fuse on the MB that controls the backlight.


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.
kaplac
Paper Tape
Posts: 3
Registered: ‎12-23-2011
Location: portland or
Views: 9,912
Message 6 of 29

Re: T400 motherboard replacement advice needed?

Sorry to revive an old thread, 

Do you know where I can find the fuse for the backlight? 

I have a feeling I might have blown mine and I'd rather not pay several hundred dollars for a replacement.

Community SeniorMod
Community SeniorMod
Posts: 10,174
Registered: ‎01-01-2010
Location: US
Views: 9,908
Message 7 of 29

Re: T400 motherboard replacement advice needed?

Check the one labled F7 (usually has a "P" on it) near the side of the LCD connector closer to the optical drive. The board uses lead-free solder which melts at a VERY high temperature. You cannot change it without a good rework station.  I just saw your other post which said no lights also.  You should also check another smaller fuse, which usually is not labled.  It is also next to the LCD connector, nearer to the CPU.  It should be blue or green.  They can blow at the same time and can be caused by a bad or the wrong inverter


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.
jack135
Paper Tape
Posts: 2
Registered: ‎12-30-2011
Location: Australia
Views: 9,842
Message 8 of 29

Re: T400 motherboard replacement advice needed?

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.

 

But when I connect to external monitor, it works. However, I can't see dual monitors display option any more, only external monitor is detected.

 

There is another thread saying it could be the switch that detects if the lid is closed not working, but it doesn't explain the LED lights not working either.

 

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

 

Thanks

Community SeniorMod
Community SeniorMod
Posts: 10,174
Registered: ‎01-01-2010
Location: US
Views: 9,838
Message 9 of 29

Re: T400 motherboard replacement advice needed?

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


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.
laptopfixer
Paper Tape
Posts: 1
Registered: ‎01-06-2012
Location: Kentucky
Views: 9,792
Message 10 of 29

Re: T400 motherboard replacement advice needed?

Does anyone know the value/specs of these two fuses? I would like to try to repair one of these motherboards.

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