Airport Express Power Supply Repair
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:
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:
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.
Here's what the two boards look like after yanking them from the plastic shells:
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:
Here's the back side 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:
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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