Saturday, May 10, 2008

Repairing an 85W Magsafe Power Adapter

A little different post today - not about leadership, process, or some great new technology. It's about fixing something yourself; fixing things sometimes pleases me almost as much as creating things. After you read this, go get a copy of Sam Martin's How to Mow The Lawn.

I love my Macbook Pro. I like the idea of the Magsafe adapter, but I'm not happy with the fact that it's single sourced. I guess iGo hasn't reached a licensing agreement with Apple for the technology, because it isn't as complex as you might think. Since it's expensive, I carried around the one adapter I have. That is ... until the cord wore out - the wrapping and unwrapping of the magsafe side eventually wore out the cable. When I took it to the Apple store I learned it wasn't repairable (don't get me started on sustainability concerns). I bought another adapter, and was hoping I might be able to fix the one I have so I don't have to repeat this problem.

I was expecting a lot of complexity in that cable, since it has numerous pins at the laptop end, and operates the little orange/green LED somehow. However, this is a no brainer to fix electrically, it's really a packaging problem, because the case was not designed to be disassembled (or re-assembled). So I thought I'd document what I did so others can keep these little guys out of the landfill, and maybe save $60 in the process. The one I repaired was the older, larger adapter.

The case appears to be a press fit with some glue. I couldn't pry it open with a screwdriver or putty knife, and since I wasn't expecting this to be so successful, I very quickly pulled out the Dremel tool cutting wheel. I arbitrarily chose the side with the metal post -- which turns out to be the best place to start. There is a heat sink behind this side that won't get hurt if you cut into it a little bit. I cut into it and started to pry.




I was doing pretty well - the sides opened up pretty easily, but was afraid to crack the case so decided to cut a little bit into the opposite side.





At this point I was a little exuberant and let the corner pieces fall out when I finally got the case open. Not a big deal but pay attention to how they fit. There are three pieces per corner where the cord wrapper device is.

This is where the real surprise hit me. There are only two wires in the coaxial cable. The white one goes down the middle and the black one is the wrapper. I was expecting the little cord protector to just slide off, but it won't.

So rather than unsolder the wires and resolder the cable to the board, I decided to use a razor knife and cut away the cord protector. This turned out to be pretty easy. After stripping away the insulation I soldered the wires to each other, and wrapped in electrician's tape (I was too lazy to find the heat shrink tubing - but that is the correct way to do it - get some at Radio Shack).


I then tested the beast before physically reassembling the case. Be careful here - I felt a slight shock when I touched the metal parts. It worked.

I superglued the case together and added hot glue where I had a large gap from the first cut, as well as around the hole where the cord comes out. I clamped it together in a vise to let it dry. Here I apparently didn't have one of the corner pieces in completely right and I broke a pin off. I used a palm sander to clean up the case exterior (and learned, by the way, that hot glue doesn't sand very well - keep it neat and remove excess with a razor. Not beautiful, and probably no longer rugged enough for travel, but it is safe and it works.

Level of Difficulty: Low
Time: 30 minutes if you don't break anything
Tools: soldering iron, Dremel with cutting wheel, #10 and #16 wirestrippers, hot glue gun, sander, vise (or clamps or rubber bands), screwdriver or putty knife, Box Cutter or Xacto
Supplies: Solder, Electrical Tape (or Heat Shrink Tubing), hot glue, superglue

12 comments:

Angel said...

Heii I´m Angel from Mexico City, and the last weekend i saw your blog because i had the same problem.

I just want to give thanks for the tip.

Jeffrey Paul Anderson said...

By the way I really wish I had used the heat shrink. The electrical tape tends to unravel... moreover you may be better off using liquid electric tape around the entry in lieu of hot glue - I suspect it is more pliable.

I also heard Apple will replace these for you -- that wasn't offered to me but maybe you need to push. It is clearly a design defect.

superserious said...

the cord right nr the magnetic connection of mine has begun to come apart - the plastic's melted round it and some wires have separated? i'm in south africa and would have to wait for apple usa to ship me one at vast expense [in my currency anyway] in the new year ... any idea whether those wires could be soldered?

gawwwwwwwwwd i am depressed

superserious said...

the cord right nr the magnetic connection of mine has begun to come apart - the plastic's melted round it and some wires have separated. i'm in south africa and would have to wait for apple usa to ship me one at vast expense [in my currency anyway] in the new year ... any idea whether those wires could be soldered?

gawwwwwwwwwd i am depressed

Jeffrey Paul Anderson said...

@superserious: I didn't open up that end, but the connection in is still just two wires. Since you've got nothing to lose I would get out the dremel and try to open it up. This would be harder than what I did.

superserious said...

Thanks mate, I think I'm going to do just that.

Giraffe said...

I used a wood chisel and a hammer to split the two sides apart. It was a 1 inch wood chisel, and worked like a charm.

Joshua S. said...

Hey thanks for posting this. I'm doing a project regarding my MacBook charger and I didn't want to have to shell out $60 just to have a spare for testing. I know the brick plugs into AC, but does it output AC, or DC (if you know)?

Joshua S. said...

*$80, not $60.

noise said...

Don't ever expect to carry it onto a plane without complications again, though. There are some available on the net now for $39

Richard said...

I just repaired mine. Had to re-solder the Plug and the Brick (60w)
Tip for those working on this.. Tie a knot in the chord so that it fits inside of the power brick.. that way no matter how had you pull there is no pressure on the leads only the case. ;)

It took me about 5 hours total.. But I'm a perfectionist and used a screw driver & hammer to break open the case.

Thanks for the post. The pics helped immensely!

Mikey UM said...

I have the same problem long ago, i just pput a hard cord in thr middle and "fix it", but withe the electrical tapes is not a good idea... so now im going to open it...

Im going to try... thanks for the tutorial hope i find some heat tubbing shrink...

From Ecuador