Using USB power in a pinch!

In my electronic repair experiences, I've twice has to find alternative power sources for cooling fans. One was an existing problem where the physical power connector on a laptop motherboard had somehow snapped off. The other was my own fault. I replaced the fan in my PS2 to reduce the noise, and accidentally shorted the leads (thank goodness for fuses; only the fan power was damaged).

To remedy both problems, I utilized an often forgotten power source: the Universal Serial Bus port. USB provides an easy source for 5 volts of direct current. This solution requires zero soldering (unless you really want to), and can be performed with a pair of scissors and a sacrificial Male-A USB cable.

Let's get started

1) First, snip the USB cable so that the MALE-A* size stays intact. You'll need enough length to reach from the external USB port (or you can solder directly to the port internally if you've got the ability) to the fan (12V-5V) you're powering.

2) Now take the Red and Black wires and strip the ends by about half an inch.**

3) Strip the ends of the fan's wire by about half an inch as well.

4) Now you'll want to plug in the USB cable, and test the fan. Make note of the configuration of wires that works. Mind the polarity! This is DC, bro, not AC.

5) Now unplug the USB cable.

6) Twist the correct stripped wire ends together, and then electrical tape them so that they don't come apart.

7) Install the fan, and then rig the wire however necessary to reach a port!

*Male-A example photo

**http://iruler.net/

After Notes:

Plan ahead. Make sure you're going to be able to reach the port from wherever the fan will sit. 

Since the power is now provided by a USB port instead of the default fan connector, there won't be any dynamic speed changes. This can be very noisy! In the case of my PS2, the fan runs constantly, but is way quieter than before. The laptop was a lot louder, however, since the fan usually only runs when the CPU reaches a set temperature.