How to: repair a broken fan in an external hard drive

I'm feeling kind of proud of myself after this ordeal, so I decided to post about it.A couple months after I bought this Maxtor OneTouch III external hard drive, it started making honking, buzzing noises. I like the fact that the enclosure has a fan (most don't) to actively keep the drive cool; I've had drives fail from overheating in the past. After a couple more months of ugly noises, it fell silent; the fan was dead. I decided to either repair the enclosure or move the drive to a new one.

I found it remarkably difficult to open. This page instructs you to open the drive by making yourself a finicky little tool to pop open several internal hooks. However, this YouTube video tells you you can just tear it off with brute force. I opted for the latter. (I have a spare enclosure in case this one couldn't be reassembled.)

The fan is tiny, only 30mm square. I found only this one in that size, so I ordered a couple. Once they arrived, I discovered they run on 12V whereas the fan they're replacing runs on 5V. DC motors usually will run on lower voltages, only slower, so I gave it a try. However, using a variable voltage source I found that the new fan would not start moving until the voltage exceeded 9V, so the 5V source wouldn't cut it.

Luckily the enclosure's power brick supplies 12V, so I knew it would be available in there somewhere. It turned out that two of the four power wires feeding the drive itself carried 12V, so I spliced them to tap in the fan wires. The drive wires were very short. The only way I was able to make the spliced wire reach the drive was by cutting all the excess plastic off the bottom of the twist connectors (blue, at the upper right corner in the photo).

I plugged it in. I turned it on. The drive came on. The fan came on. Woo! Hoo!