The cord coming out of my Powerbook AC adapter shorted out. Eventually, it even sparked and started to smoke. After this happened, having nothing to lose, I ripped it apart and made it work again. This is the story.
Step 1: The Problem
This explains how to fix an Apple Powerbook AC adapter that has a shorting cord. If your power adapter has a different problem, there might still be useful information here for you.
Step 2: Chop It
Since the cord is shorting, we ultimately want to cut out the place where the short is and splice the good parts back together. Go ahead and chop the cable off now as it will just get in the way if you have to open the case.
The short in my adapter was so close to the point where the cord enters the casing that I needed to open up the case to get to the length of good cord inside. Apple doesn't expect these cases to be opened and, as such, they super-glued them shut. This makes opening them a real pain.
Step 3: Get Inside
Now comes the hard part: getting the case open. I've seen suggestions of using a small screwdriver and a hammer. This might work fairly well to crack the seal. I didn't have a hammer, so I sawed away at the seam for a while and then pried around with a screwdriver. Experiment, pry, bend. Just get the seal around the outside cracked.
Once the seal is cracked, you still aren't quite home free because there's a metal shield inside that's glued to the top of the case. If you're pulling and it springs a little bit but doesn't open, get up under the shield with a screwdriver and gently separate it from the top. You can see the shield in image 2, below.
Step 4: Expose Some Wire
The power cord itself isn't your standard two-wire cable. Instead, it's a very thin coaxial setup. The core provides the ground and the outer cage acts as a ground. In order to splice these, we first need to separate them.
Start by carefully stripping off the outer casing. Wire strippers could work here, but be careful not to cut through the ground wires. I didn't have a wire stripper, so I used a knife and my fingernails. Once the outer casing is off, separate the ground wires and strip the casing from the inner cable. There will be some thin green floss mixed in to the ground cage that provides padding and strength to the cable that you can separate out and trim off.
Now we need to get a some exposed wire on the adapter side to splice the cord on to. See that little plastic thing that the cord passes through as it enters the case? It keeps the cord from getting yanked off of the board when you pull on it. Inside the plastic thing, the cord is tied in a knot. If you can cut away the plastic thing without cutting through the cable, you can untie the knot and get a decent length of wire to work with. As you can see in the second photo, I couldn't, but it worked out anyway.
Once you have the cord exposed, repeat the stripping process from earlier and splice away. To do this properly, you should probably twist the wires and then bind them with solder. I didn't feel like getting out my soldering iron so I just wrapped them with electrical tape.
Step 5: Wrap It Up
It's time to wrap things back up. Before you start reassembly, it's probably a good idea to test out your wiring to make sure it works.
When you're putting things together, wrap the cable in such a way as to protect both the splice point and the board connection from stress. You don't want all of your hard work to be undone by a careless yank on your cord.
Once you've got everything pretty secured the way you want it, tape it up (or glue it, or encase the whole thing in carbonite).