Wednesday, April 2, 2014

Overheating Apple Time Capsule

I was forced to convert to Apple products a few years ago to allow me to start building iOS Apps. For the most part I've been happy with their computers & mobile devices. One item that has caused me constant problems is the Time Capsule backup unit. As I found out, it looks cool, but runs HOT!

FYI: The TC is a 4th Generation 2TB model

On warmer days, it would lock up and eventually shut down. Of course, it happened at the most inopportune times. Since my office Internet routes through it, not only would my old backups go away, but Internet traffic would be down. When I started to explore what was going on, I found many people complaining about the same thing: an under-performing cooling system.

The Time Capsule seems poorly designed and/or badly constructed. I say that because the internal fan seems to only come on in an overheated situation. It doesn't keep it constantly cool. Additionally, the fan is butted up directly at the wall hard drive, leaving little room for airflow to come out and around the unit.

There are several online mods (here and here), but I decided to implement my own.  This mod combines their ideas, but the fan doesn't sound like a jet engine on takeoff when you get done.

As you can see from the infrared image of the drive, the hottest part seems to be in back, right where the power supply electronics are located.  The components that take line voltage and step it into a stable power supply create a lot of heat.  Often it was hot enough that I couldn't keep my hand pressed on the unit.

Strange enough, the hard drive was relatively cool.  It is located in the lower right quadrant on the infrared image.

The Nitty-Gritty of the Mod

After removing the rubber base with a heat gun, I got access to the bottom aluminum plate.  After removing about 1000 screws, the internals opened up.  Obviously, the unit must be disconnected from power.

After surveying the situation, I removed the fan and snipped the third wire (See pic).  I put it all back together and started up the unit.  With that wire snipped, the fan runs at 100%.  It cools like crazy, but is much too loud.  So, I needed to add resistance to the #1 wire.

I then took it all apart again.  Next, I removed the fan, snipped the #1 (see the arrows in the pic.)  Then I soldiered in two 100 ohm resisters in parallel.  The leads on each resistor are twisted with the duplicate lead on the other resistor putting them in parallel. The two ends of the #1 wire then were stripped and each end was soldiered to each side of the twisted resistors.

The new resistance (which turns in 50 ohms) causes the fan to run at a much lower speed, but still provide adequate cooling.  I finished the electrical job by wrapping the entire resistor assembly with electrical tape.

Next, with a Sharpie I also marked exactly where the fan was located on top of the aluminum plate.  I drilled a pilot hole, then a 1 1/2" diameter hole to get the max amount to air into the unit.

Finally, in putting it all back together, I rotated the fan 90 degrees so that the output of the fan was pointing at the electronic boards (not the hard drive.)  I used electrical tape to ensure the most of the air goes through the electronics and not out the sides (See pic).

To finish it all off, I put rubber feet from Lowe's on the unit to give it about 1" of clearance under the unit.

When I put it all back together two great things happened: first the fan ran at a level that can't be heard unless you put your ear up to the unit.  Second, it cooled the system down to a level it can handle.  The max temperature I could find was 91.4 F.  That's much better than the 120 F I was getting before the mod.

Thanks to my neighbor who works for Axis cameras for loaning me the best IR camera I've ever seen: the Axis Q1910.

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