Airport Express Power Supply Repair

Posted: Mar 25, 2009

I bought an Apple Airport Express off Craigslist a couple months ago so I can send music to my living room stereo via Airtunes. The little bugger quit working about a month in though, so I tossed it in a drawer to be put on Ebay for scrap or otherwise dealt with. As is wont to happen this semester, however, one day recently I got bored and went hunting around my room for things to do. I ran across the Airport Express and started wondering what was wrong with it. Here's the story of the teardown and my attempts at repairing it:

Apple, being Apple, decided to make it im-freaking-possible to get into the guts of the Airport Express. The case is two halves of thick plastic ultrasonically welded together, making it a serious pain in the ass to get it open. I tried prying it apart with a series of screwdrivers:

Attempting to pry it open

This was the wrong way to go about it. After a half hour of struggling with various sizes of screwdriver, I got impatient and grabbed my hand-saw. I carefully sawed around the three sides without the connectors. I tried to saw down the plastic until I was just starting to break through to the inside of the box, but this was pretty tricky in spots. Eventually I got impatient and went back to the screwdrivers:

Back to screwdrivers

After a good bit of prying and swearing, I managed to get the thing open. The Airport Express internals are split into two halves... a power board, and the airport-express-stuff board, with just a power cable connecting the two:


Once the Airport Express is open, there are a few screws holding the Airport motherboard in place. I pulled those screws and then popped the metal shielding off of the board.

Airport motherboard

Here's what the two boards look like after yanking them from the plastic shells:

The boards

The motherboard is actually made out of two boards. The larger board holds all the RF and computing stuff, and the smaller daughterboard holds the audio interface circuit. Here's a pic of the two separated:

Board and Daughterboard

Here's the back side of the motherboard:

Back of the motherboard

Next, I sat down to try to figure out what was wrong with the airport express. I tossed a volt-meter on the power supply outputs and plugged it in, and it turns out the power supply was shot. Neither the 5V or 3.3V outputs were pumping out any juice. I briefly considered trying to troubleshoot the supply, but I decided it was easier jut to chuck it  and throw some wall-warts on the inputs. I had a 3.3V wall-wart, but no 5V supply, so I used the 3.3V supply and a 12V supply running through a TI PT5101A 5V, 1A switching power supply:

Complete with warts

Unfortunately, the 3.3V and 12V wall warts I had sitting around were only 300mA and 500mA supplies, whereas the Airport Express's original power supply was spec'd at 1.21A and 0.7A for each voltage. I was hoping that the Airport wouldn't require that much power to operate, but it turns out that it does. When I plugged the power supplies in, the green LED briefly lit up and slowly faded out. I'm going to try to hunt down some more powerful supplies and try again.

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