How to fix a Powerbook G4 power adapter

February 26th, 2007

All products seem to know when their warranties are going to run out ;), unfortunately even Apple Products. We have several macs in our group and suddenly 3 of them went kaput one after the other. After calling Apple I found out that the (3 year extended Apple Support) warranties had run out in Nov. 2006, and we would need to buy three new ones, $79 each.

This is obviously not a new problem as I found out from an old blogpost.

Usually one of three things go wrong:

i) There is a snag in the wire, and it shorts itself, burning out at the snag. This snag usually develops very close to where the DC (thinner wire) comes out of the power adapter. In fact so close, that the we have to open the box to solder the wires, after cutting out the burnt part.
ii) The pin at the DC end drops out or gets bent

iii) The whole thing smokes, and thats the end of it.
I had one of each. So, I took the good end from the smoked one, to replace the broken one. For the one with the burnt/snagged cable I meant to cut out the burnt part and solder it back again.

But there were some more complications. For DC voltage I had expected two wires. It turns out that its actually a very thin coax, which makes it a bit harder to peel, separate, and solder. The outer one is Ground, and the inner one is 24.5V, see below:
It seems, Apple never meant for these things to be opened. There are no screws and I had to pry it apart using a screw-driver and a hammer. Even worse, its not merely push-fit, it is super-glued together making it harder to take apart.

Here is what you need: (i) A small flat-head screw-driver, (ii) A hammer, (iii) A sharp razor blade, or wire peeler, and (iv) a soldering gun. The image below also shows the inners of the plastic half, with some glue still sticking to it.

Once I got the two wires soldered together, it worked just fine, tested it on a multimeter first of course.

The other one didn’t turn out as I expected, it had some other damage inside after I managed to pry the plastic covers apart, some solders had come loose and there wasn’t enough wire to solder it together. So ended up trashing two, but nevertheless managed to make one good one.

Soldered together and insulated

I put a knot around the soldered ends, so the soldered joint wouldn’t get pulled apart if accidentally strained. Doesn’t look pretty :) but works fine.
The newer MacBook has a sturdier wire and will hopefully last longer than the older version. Also the magnetic contacts won’t have the the pin related problems — there is no pin.