Thursday, October 27, 2005

apple power supply repair

My power adapter for my little bitty powerbook decided to attempt a slow suicide. The wire that goes from the brick to the computer had become weak and seemed to have broken in the casing. If I wiggled it carefully, it caused pretty sparks.

So I decided to attempt bypass surgery, or at least crack the sucker open and see what was wrong. Surfing the web, I found one site where some dude had fixed a similar problem in his. His instructions called for a hammer and screwdriver.

I pried at the seams with a very small screwdriver, but couldn't get the sucker to budge, so I took a hammer to it and made a hole in the side big enough to insert a large screwdriver. With the big poppa in there, I twisted and cracked it open along the seams. This took quite a bit of time, but eventually I got the case to come apart.

Once I had the case apart, I plugged it back in to see where the wire was shorting. It was easy to spot, since when I flexed the wire it glowed and sizzled in a specific spot. After identifying it, I cut out a one-inch segment of the wire and proceeded with figuring out how to put it back together.

I noticed that there was a small wire that was encased and essentially shielded with stranded wire. The shielding and the smaller lead split off inside the case and are actually separate wires. Because of this, I stripped the wire all the way to separate the two for repair.

I also stripped the other newly-cut end of the wire after realizing there was just two wires (and not three like the end of the plug suggests). The internal one was pretty small, and I had to look at it through a magnifier to separate the wire strands from the kevlar or whatever the strengthening cord inside was. To avoid polluting my solder (and smelling bad), I removed the non-metal cord from the exposed parts of the wire.

All that taken care of, I twisted together the internal wire ends (grey), put a clip around it, crimped it, soldered the end, then sealed it shut with stretched electrical tape. Then I twisted and soldered the other pair, and taped it then taped the whole bundle together as best insulated as I could. Fitting that sucker back into the case was a trip (as you can see it's large) but I was able to weasel it back in and almost re-winch the wire in the round grommet thingy that holds the wire tight in the case. That stupid grommet thing caused the wire to weaken, but at least the wire didn't pull out of the circuit board.

Finally, I took a deep breath and plugged 'er in! No smoke, no strange noises. I wiggled the wire, no short, no sparks. Plugged it into the laptop and the power light turned orange! Yay for charging my battery. It charged my battery all night and didn't explode -- in fact, the power brick didn't even get as hot as it used to. Perhaps that weak wire was causing it to heat up in the past. After all, it is just a 45W supply (Apple currently sells a 65W supply that works on all of their laptops).

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