The IBM ThinkPad T40 is a notebook computer with a high priority on durability and mobility. The T40 model was released in March 2005 as part of Lenovo's T Series mobile workstations and is marketed towards mainstream professionals.

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Works perfectly, unless it's twisted.

Found a T40 that seems to work perfectly except for one tiny detail that I’m having a !&&* of a time figuring out: When you “twist” the computer slightly, the computer “sort of” momentarily crashes.

Deeper explanation…

Set the computer on a table, turn it on, and it works perfectly. However, if you pick it up off the table and slightly twist the base, the screen goes dark and a few other things happen (explained in a moment). It’s a specific twisting action; with the computer open, the hard drive is under the right palm rest and the PCMCIA cage is under the left palm rest. If you apply pressure on top of the right palm rest and below the left palm rest, the base will slightly twist so that the right side (the hard drive side) is lower. In that position the screen goes black (as if the video cable were unplugged) and the hard drive stops accessing; the computer is effectively “crashed” at this point. It doesn’t respond to a network ping or anything. Twist it back so that the left side (the PCMCIA side) is lower and the screen and hard drive both “wake up” and things continue like nothing ever happened. As long as the computer is kept flat/level/twist-free, it will work perfectly.

Once in awhile, like when I’m experimenting by twisting it multiple times, the screen will get some odd artifacts on it. Even more rarely, the computer will actually crash (complete lack of all activity).

In testing…

  • Definitely not software-related as I’ve clean-installed the OS, so nothing bad is there.
  • Disconnecting the on-board video cable and driving only an external screen does not solve the problem.
  • Removing the keyboard and track pad assemblies does not solve the problem.
  • Unplugging, cleaning, and reseating every internal cable/harness/etc does not solve the problem.
  • Removing the battery and running only on AC power does not solve the problem.
  • I was thinking perhaps there was a short happening below the ATA bus (not SATA) at the lower enclosure, so I insulated it with a bit of electrical tape. No help there.

Clearly there’s some kind of intermittent contact issue happening. Twisting in one direction disconnects “something” and twisting in the other reconnects it. I just have no idea where I might look to find where that “something” might be. Ideas?

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What about the hard drive? Could it be the culprit here, especially given its age? Do you happen to have a USB to ATA adapter so you can test the drive with another computer (like gently lifting it and balancing it from left to right)?

Does that particular model have a broken free-fall sensor that gets triggered every time you twist the laptop (those are accelerometers that are supposed to detect if the computer is falling, turn off the display and the drive in case it does)?


It's definitely not the hard drive. Even if I remove the hard drive and give it the "twist test", the problem persists.

It's definitely a bad connection on the motherboard somewhere. I've removed the motherboard from the case and powered it up that way with only an external monitor attached and the problem persists. I've decided to forego the repair and part out the machine instead.




This is actually quite a common problem for this generation of laptop from IBM. The T4x series have an issue with the internal GPU coming ‘loose’ from the motherboard over time, usually increasing the problem when you lift the unit from the palmrest area. The only way to fully repair this would be a reflow job or motherboard replacement, but many people have found temporary fixes by applying pressure to the GPU, etc.

There is a good post about it on the ThinkPad Forums that I’d recommend checking out.


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Hello, I have the same problem with my IBM T40, After three times moving our house I took it out of our storage box and installed a new OS (antix) and it was running perfectly until I lifted one side of the machine or apply pressure on a corner. If I press two diagonal corners the screen turns on and when I loosen the pressure it goes black but with the background light still on. I dissassebled/reassembled all the câbles and connections and the problem is less severe now. But as Alex Niculescu pointed out I found a little black switch on the screen cable connexion and got an idea that maybe when the plastic frame is distorted it pops up and turns the screen off? It's kinda funny this problem. Thanks Alena




Steve Godun crwdns2893898:0crwdne2893898:0

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