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

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Anonymous @anonymous1072

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发帖于: 2015年4月5日

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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.

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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.

由 unsubstantiated 完成的 2017年6月29日

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mayer @mayer

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发帖于: 2015年4月6日

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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.

由 Anonymous 完成的 2015年4月6日

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!

由 Nicolae Mogoreanu 完成的 2017年5月18日

Had the same problem.

I found on few solutions to heat up the power adaptor, first I thought it's stupid....

But as described above, had only that 0,44V on power line, after about 15 minutes of sitting on power adapter suddenly the MacBook Air (mid2011) switched on by it self !

Don't know what might be the reason for it.

由 Sylwester Sirocki 完成的 2018年4月19日

Sylwester - It's best to replace the charger with a new one. Heating it won't really fix it only postpone the inevitable.

由 Dan 完成的 2018年4月19日

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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. — unsubstantiated
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. — Anonymous
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! — Nicolae Mogoreanu
Had the same problem.

I found on few solutions to heat up the power adaptor, first I thought it's stupid....

But as described above, had only that 0,44V on power line, after about 15 minutes of sitting on power adapter suddenly the MacBook Air (mid2011) switched on by it self !

Don't know what might be the reason for it. — Sylwester Sirocki
Sylwester - It's best to replace the charger with a new one. Heating it won't really fix it only postpone the inevitable. — Dan

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

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