I noticed something rather weird with my MacBook Pro, if I touch the computer after charging the battery it feels like it’s vibrating. It’s actually not vibrating but that’s the best word to describe the feeling when I touch the computer, especially above the F-keys and around the palm rest area. It’s some kind of static charge that I have no tools to measure but it’s quite noticeable. The only way to discharge it is to slide my hands a few times left-right along the computer surface and the thing is soon gone.
I wasn’t sure where it comes from so I asked in a few internet forums and someone suggested not to use the short power-plug adapter but the long cable instead. So I tried and it worked indeed. But why, I wondered. Some people mentioned possible bad earthing and I found it hard to believe as I have no problems with earthing in my house.
I took the power supply into my hands and noticed something unusual. There are two ways to connect your power supply to the power source, one is to use the long cable and the other is to use the small adapter that clicks into the power adapter itself. I noticed that the small adapter is not eartherd. See the image below, the one on the right has only two prongs, while the one on the left has three. The third prong is the earth lead.
The pictures are of the Australian standard power plugs, it may look different in your country but the adapter we have here has no earth at all.
If you look at the power supply itself, there is a big nipple that is actually the ground connector on the power supply. The connector that attaches the cable to the power supply has the metal contacts on each side of the slot (see below) while the small adapter doesn’t.
I’m not entirely clear why Apple hasn’t included earth connection on the adapter, could it be that there is valid reason or maybe someone in technical department just had a few too many the night before.
[tags] Macbook Pro, vibration [/tags]
I really don’t see why they didn’t bother including a third groundi ng prong on the non-chord plug. Makes little sense to me.
I’ve notice this too. In USA, I didn’t notice. I’m now in India and the shock is quite severe. I’ve found that if I rest the laptop on my bare legs, the wrist shock goes away. I’ll try the long cord next. I’ve been using the short plug.
Hi, and first let me thank you for this page. I’ve been wondering all the evening why my brand MBP was vibrating when it was plugged.
In France, some old plugs are not grounded, they have only two prongs. My MBP was plugged to one of them in my room (even with the long cable), that’s why it didn’t vibrate in my office equiped with normal grounded plugs. I have really no skill in technics, so I didn’t get it.
Thanks again for the help!
Yay!! More vibrating Macs!! Here in South Africa even the long plug only has live and neutral! Basically, I’m screwed unless I rip the end off the plug and put an earthed one on!! What a ridiculous oversight on such a pricey machine!!
The nightly curse, as soon as my arms get weak and I rest them on the mac, I get a ZAP…
I have the same thing here in Bahrain, the long cable has no ground, i dont know what to do? as soon as I pug in to charge i get the vibration.
Personally i quite like the vibrating feeling! I find myself absendmindedly stroking my macbook whenever it gets ‘the buzz’! ;)
Hi,
I am in India, with an American Macbook, and I still get the vibration even when using the three pronged long cord. I’ve tried it in about three different locations, but it’s quite possible that none of them have had grounded power.
Any ideas why my long cord isn’t grounding the power?
Is this bad for my hard drive or any other essential functions?
Thank you in advance for your help!!
Susan