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ThinkPad NotebooksThinkPad: T400 / T500 and newer T series Laptops
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T500 - Lid Close Sensor broken?

2017-09-05, 12:32 PM



I have the problem that the backlight of my T500 is not working anymore. I already checked Fuse F7 which is working and I also changed the Inverter, but nothing solved the problem. My last idea is that the lid closing sensor is not broken, so how can I test it? Where is it located?


Also if I connect an external monitor, the BIOS will be always displayed there which I think is because the Lid Closing Switch always sends the signal the lid is closed.


I hope you can help me and thank you in advance!


Best regards



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Re: T500 - Lid Close Sensor broken?

2017-09-05, 15:11 PM

It has a CCFL bulb, and they do die, sometimes.


I don't remember where the switch is on the T500 - it may be near the camera, but it is easy to figure out.  The switch (Hall sensor) is a magnetic switch inside the lid that is triggered when the face of the screen approaches the palm rest.  There is a magnet that operates the switch inside the palmrest.  Take a little screw and push it around on the palmrest until it snaps to the magnet.  My guess is that it will be near the touchpad buttons, but sometimes they are about halfway up a hinge, usually on the left side.


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