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Released May 2004. Identified by model number T42 of the ThinkPad T40 series.

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failure of fingerprint reader, usb, and sound

I lost all three of these hardware options at once. I am trying to figure out what is the root source of the problem.

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I am hoping that AB Cellars will catch my post and respond back to me. I found that the USB circuit is completely dead after testing the USB with an optical mouse. While this Laptop is a little slow and aged, I would like to get it working at full capacity again.


Rich, check his user profile. His email address is posted on there and you might want to contact him through email.


The problem is in the USB power circuit(s) on the USB ports. I may have reference to a couple of web sites that cover troubleshooting those circuits. The problems with the others could be power circuit(s) or the Southbridge. Until you test the power circuits you won't know. Repairing the power circuit(s) will be replacing the MOSFETs and what ever caused them to go out and/or they took out when they died. If there is a problem with the Southbridge, it will need relowed or reballed. You might be better off buying a motherboard or selling this for parts, depending on your skill level with electronic repair. Then again it might be a good board to learn on, before you do either. Here is a link to the service manual: http://download.lenovo.com/ibmdl/pub/pc/...


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Gewählte Lösung

The sound and the fingerprint reader are piggy backed into the USB channels through emulation on this. Each channel handles 2 devices. Hook up a USB powered device such as a known good optical mouse - something with a LED light. If the LED on the optical mouse works, but the computer doesn't respond to the gestures, then most likely the power circuit is good and the southbridge (USB controller) is bad. If the LED is not lit on the mouse/device then the power circuit is bad on those channels - most likely the MOSFET(s) or what drives them. Please let us know the results of the LED test so we can further advise you.

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Thanks for the input. Trying to locate an optical mouse to perform the test. I will reply once test is performed.


Allright, I found a USB Optical device which did not work at all on either of the USB ports. I will await your comments on how to proceed from here.


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Rich wird auf ewig dankbar sein.

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