I have a 2010 Macbook Pro with a MagSafe T Power adapter.

The power adapter makes a buzzing/hissing/fuzzy noise when it is plugged into the wall.

When it is plugged into my mac, my light turns green for about a second, then orange for 5-10 seconds, and then no charge.

I am not sure if the problem is my Macbook Pro battery, or my adapter?

How can I diagnose/troubleshoot, and what are the best recommendations?

  • Many power adapters do this, working or not. Swap in a different power adapter and see if your laptop charges all the way. – Brad Jul 21 '11 at 15:14

The troubleshooting is not particularly difficult, but you do need the extra equipment, and that is the trick. Most times, you end up having to buy a part or two based on your best guess as to what is wrong, and just hope that it works. You can avoid this if you have access to a multimeter and can test the power supply. You can also test your battery too.

With a multimeter, you would just test to make sure that the voltage output is what is listed on the adapter. If it is correct, it is probably not the adapter.

Other than that, it does sound like it is probably the adapter itself, so I would start buy buying a replacement. The noise will go away, and hopefully, your battery will charge fully. If the battery does not charge fully, you will need to replace that too.

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