Wiring little wires to stuff or “How did I get fingerprint scanner”

So I had/have a semi-old dead laptop. The motherboard is dead, everything else works. It’s a Dell XPS M1330. It has a fingerprint scanner that made my curious. How does it work? How is it connected and can I use it?

I ripped the laptop open and extracted all kinds of fun stuff including the fingerprint sensor.

It has a little chip with a writing  / / TCD42A1DN0 / /

So I started investigating.

First thing that threw me off was the 6 pin ribbon cable (USB typically uses 4).

  • Finding ground pin is the easiest – Found that.

  • Found the power pin- It was a line that had a capacitor connected with the ground. So I assumed this was the power pin.

  • Two pins are unpopulated.

  • Two pins are connected to resistors – starts to seem like USB data lines~.





Interfacing it.

Typically all internal laptop stuff uses 3.3V. So that seemed a safe way to go. I need to use a voltage converter to step down from 5V.

It has a ribbon cable, so that’s a no go. Removed that and the plug and decided to connect wires directly to it.

This needs some soldering under a microscope because this stuff is tiny.

Soldered everything up and time to test.

USB data + and –  //connected it randomly, 50/50 chance that it goes correctly the first time. (But in real life I connect it always backwards the first time.)



Connected it a perforated board and hooked up the USB cable.



Time to roll

Connected to a computer. Windows detected it (Data+ and Data- went right ways the first time). Windows installed drivers automatically and restarted the computer.


Voila, it is working!



  1. hi i need a help here i don't know how to pinout my finger print reader ... can you help me

  2. Aluminum wire was used from the mid 1960's to the late 1970's. It is rare to find aluminum wire in homes constructed after 1980.Jim Rohal

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