Monday, January 14, 2008

Magsafe Connector Disassembly

The chord nearest the Magsafe plug on a modern Apple laptop is under a good deal of mechanical stress, and mine finally gave out; the outer layer of wire looked like loose steel wool. So I decided to take the plug apart:






Notice that black bit on the PCB in the left-hand image? That's a chip, identified by the following text:

A3
2100
613A1

It most likely controls the switch between the orange "charging" LED indicator and the green "powered" LED. However, I wonder if this chip doesn't hold the answer to another mystery: why won't the Macbook battery charge off the Magsafe airline adapter?

For further information on the subject, I'd suggest Stuart Schmitt's guide to hacking the MagSafe cable for use w/ a standard DC transformer.

16 comments:

Jean-Pierre said...

Hey Kieran, I had exactly the same problem. How did you solve it ?

I personnally soldered the thing back together, but this is just an fragile emergency fix :
- do you know where to find a replacement cord+plug ?

cheers from Paris,
Jean-Pierre

kieran hervold said...

My apologies for the delayed response.

My soldering held it together for a few weeks, but I wound up buying a new Magsafe tip on Ebay for around $15 -- much cheaper than a new transformer would have been.

Try searching ebay for "Kensington Smart Tip for Magsafe;" currently, there's one listed on ebay as item # 200242661468.

I replaced the wire w/ some proper copper wire I salvaged from an old power chord.

Zbigniewq said...

Hello,

I have most likely magsafe connector problem. Could you tell how non-destrutively go about disasembling the head of the connector? Thanks in advance

kieran hervold said...

Zbigniewq,

I can't say there was any particular trick to prying it apart; it was mostly a matter of wedging a knife between the white plastic shell and the underlying metal. Go in from the business end of the plug.

That said, any fix you manage will probably be short-lived. I'd strongly suggest searching Ebay for "magsafe Kensington," and soldering on one of those $15 tips.

Just make sure you get the polarity right. There's a nice diagram here:

http://en.wikipedia.org/wiki/MagSafe

Wireless Sensor Networks Research said...

Hi. Just wondering if you know how might the white housing should come off the magsafe for me to repair to cord (broke off from fraying). I don't want to break it, someone mentioned it should slide off. Would a certain type of tool help so that I don't damage the housing?

Thanks from Portland Oregon,
Judy

kieran hervold said...

Judy,

In order to get the white housing off, I slid a small knife blade between the housing and the underlying glue. (The assembly is protected and attached by something like glue-gun glue.)

I would recommend buying a replacement tip off ebay, however. Search for "Kensington Smart Tip for Magsafe." I found it impossible to re-solder the connection in a reliable fashion; it just broke and required more patching every couple of weeks.

Blake said...

Hi Kieran, my Magsafe died so I took it apart and wrecked the circuit board and housing. I can easily connect DC power to the proper pins and power up the computer, but the center pin is not connected to anything and the battery won't charge. Any ideas on what to do with the center pin? Thanks, Blake

kieran hervold said...

Blake: I don't know what the center pin does, exactly, nor what purpose the chip serves.

However, if you're willing to risk your laptop to experiment, Stuart Schmitt's guide notes that "With an ohmmeter, pin 3 registers about 426 kΩ to the V- pins and no circuit with the V+ pins."

I just tested a live, intact MagSafe connector, and I do see voltage between the center pin and the V+ ground, consistent with a connection between the center pin and the V- pin.

So you could try connecting V- to the center pin via a 500 kOhm resistor, if you can find such a thing. It might be risky.

Steve said...

Standard resistor values include 430kΩ. Here's a link to a Mouser part, only a nickel per!

Steve said...

Using this as encouragement, I performed surgery on my screwed-up Magsafe adapter today. I snipped the wire; removed the collar; slid a box cutter blade down each long side of the adapter; then gently tapped the core out with a small Torx screwdriver.

Once out, it was pretty easy to clear the three solder points of the old detritus, and tap in clean leads from the existing cable. I used a lot of well-placed and tight electrical tape to seal it up. Works great, just like the original.

It should be noted that I am not using a Radio Shack soldering iron, but rather a good iron with an SMT tip.

kieran hervold said...

Steve,

Nice! I'm glad I could provide the inspiration ;)

My only advice would be to make sure you really bind the repair up tightly. My original repair failed within a few weeks, and the magnetic attachment point and pin section eventually fell off the circuit board, necessitating a new Kensington-supplied plug.

Jeremy said...

I wonder if you know if you can replace the end connector on an iBook PSU unit for a macsafe connector.
There are no connectors coming up in eBay for 'Kensington Smart Tip for Magsafe' or combinations of... can you recommend shops that sold them before to try and source directly?
Thanks from England,
Jeremy

Anonymous said...

Hey everybody. The ground wire near the L section of the magsafe adapter was broken so i kinda opened it up to connect it again... The thing is that i found a small circuit inside that helps in lighting the LED. While i was opening i cut the circuit by mistake and so i removed the LED indicators from both the sides... In short my adapter only has the +ve and -ve connections... Now whenever i connect it to my laptop, I get the supply from the adapter but it doesn't charge my battery (battery status-"not charging") because the charge control pin is not connected to anything... Can anyone tell me what to do or how to connect the charge control pin so that it starts charging my battery again? I can add additional components like resistors, etc if necessary...

Matt said...

Hey blake... I have the same problem... Just wanted to know if kieran's idea worked...

kieran hervold said...

Anonymous, Blake:

I've verified that my Mac won't charge if the middle LED pin is covered with an insulator.

I imagine you could put a resistor between the middle LED pin and V-; Stuart Schmitt reports that "pin 3 registers about 426 kΩ to the V- pins."

However, there will be some risk to your Macbook ...

NustianUzair said...

my magsafe connector pin was separated from the cord. i tried to solder the wire with connector but didn't cared about the polarity of both soldering wires.after soldering and connecting it to my MacBook Pro,it didn't work.I also tried to charge my MacBook Pro from a brand new magsafe but it shows no chrging.please tell me what is problem? is my powersupply assembly got screwed?or is there any circuit breaker in the assembly which has turned off??all this mess up was due to changing polarity??