Thinkpads Forum

Very grateful to have found this forum, and I was able to run down the cause of my T410's spontaneous wake up issue as a result of reading it. The method for the T410 is a little different than that described elsewhere, so I thought I would share.

There are many posted gripes on the WWW regarding a Thinkpad with lid closed spontaneously waking up when the owner doesn't want it to. It will awaken in a computer bag, and gladly cook away until the battery runs out or the thermal switch goes open. On many occasions I opened my bag and found my precious T410 blazing hot.

Another post informed me that the lid detector is a Hall effect sensor in the screen bezel that detects the proximity of a magnet in the keyboard frame.

The critical piece of information in the case of the T410 is that the hidden magnet lies very close to the upper edge of the frame at about 11 o'clock to the blue ThinkPad button. I found it by sweeping the area with a small razor blade until it stuck to the magnet--sort of like a stud finder.

After some trial and error, it was clear that lid jiggling varies the distance between the Hall sensor and the magnet, which leads to a signal from the sensor, which leads to a wake up.

By mounting a vinyl bumper (used to damped the closure of cabinet doors; a rounded disk 25mm in diameter and 9mm tall) on top of the magnet location, it was possible to completely inhibit false signals, and thus my baby is now able to remain asleep while in its crib : - )

Hope this works for you.

Nice find.

Generally, the best way it to just disable sleep on lid close (which also disable wake on lid open). However, some Thinkpads (e.g. X220, and probably others in this series) have a bug where even if you disabled sleep on lid close, sometimes it wakes up on lid open. In that case, you can have the issue you described. I am not sure if it can happen on a T410, but it never happened to me.

I have difficulty understanding how the lid can close over a 9mm high obstacle.
Can you link to a picture please?

The way I read between the lines of this fix, the bumper goes on the top of the lid. When the laptop is inserted into the laptop bag, it provides some pressure and/or prevents the lid from flexing since the bumper would be in contact with the (side) of the laptop bag. At least that is what makes sense to me. You're right - you can't close the lid over something that's 9mm thick (i.e., bumper placed on top of the keyboard bezel). Besides, doing that would be counterproductive because now you are increasing the distance between the LCD bezel (Hall-effect switch) and the keyboard bezel (magnet) and the system would probably never detect the lid closing.

Were it my problem, I'd opt to install a block of extra padding down inside the bag instead of putting something on the outside of the laptop.