AC adapter for MacBook, MacBook Pro, and MacBook Air

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Magsafe adapter doesn't work. What should I check?

Hi.

My Magsafe 1 AC adapter (from Macbook Air, 45W) doesn't work suddenly. No LED indication what so ever. No damaged visually find, even wire is fine.

I have a volt-meter, so I can check some resists or volt. Please let me know what should I check...

These are current status :

Pin 1+2 : Not shorted. 0.44V, 200k Ohm when not plugged in, 5M Ohm when plugged in.

Pin 4+5 : Not shorted. 0.44V, 130k Ohm when not plugged in, 2M Ohm when plugged in.

Pin 1+5 or 2+4 : Shorted, 0.0V, 0 Ohm

What I heard, it should about 6V when it's not connected to notebook. Mine does 0.4V only.

Help me please.

Answered! View the answer I have this problem too

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Standby output of Apple's MagSafe Power Adapters varies between models. Yes it is often said to be "6V", but that is "old knowledge" which pre-dates 45W and MagSafe 2 models. (I'll share two standby potentials which I measure: Model A1424 is around 3,15 V; Model A1435 is around 0,6 V.)

Unfortunately, I am not able to help you with your misbehaving unit. I hope this little bit of knowledge will be useful to anyone, whom suspects their unit is faulty just because its output potential is not 6 volt.

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Deck the Halls
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Here a picture (on the right) or the pin outs: http://en.wikipedia.org/wiki/MagSafe

Pin 1 0 V

Pin 2 V+ @ 14.5 / 16.5 / 18.5 / 20 V DC

Pin 3 Charge control pin

Pin 4 V+ @ 14.5 / 16.5 / 18.5 / 20 V DC

Pin 5 0 V

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I do know that. But currently pin 2 and 4 only out 0.44V which supposed to out 6.8V with regular reference like Wiki.

BTW, I checked well working adapter too and it also out 0.44V. I don't know what to do next.

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I tried to reuse a 45w MagSafe adapter for hobby purposes and I'm also getting 0.44v on the power line and 200k Ohm resistance. I tried to put a 39.41k load on it to make it start delivering power (works on other Mac power supply) and it didn't want to start. It would be helpful if anyone knows how to bootstrap this power adapter.

Thank you!

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