My Macbook Pro (aluminium case) gives me a very mild electrical tingle when I rest my arms on the palm rests either side of the track pad. I’ve noticed similar sensations from other things such as my home theatre receiver. Anyone know what is causing this and whether it is bad?
If it was just the Macbook, I’d suspect an electrical problem such as a bad ground, or maybe that you’re just trembling with excitement from touching a shiny Apple product.
But if it’s a whole range of things, then it’s got to be something to do with your hands, or maybe your house wiring.
Does anyone else report this phenomenon when touching your equipment in the same way? Does it happen on other people’s kit, at other people’s houses?
I’ve only started noticing it on the Macbook at someone else’s house. That’s not to say it didn’t happen at my own house but I haven’t been back there since I noticed it while away. The only other person in a position to notice it at out house is my wife and she doesn’t generally touch the home theatre stuff (not because she’s a simple woman who doesn’t deal with manly electrical stuff, she just has no reason to use anything other than the remote.)
The power adapter has also been acting up a bit, it can be plugged in in any orientation but won’t charge the battery when plugged in a certain way (though it will still power the laptop.) I think, but am not sure, that this has all started happening after a violent electrical storm that fried the telephone and DSL modem in this house a couple of nights ago. The Macbook was running on battery at the time but the adapter was plugged into the wall.
I notice something similar when I use the 2-prong adapter, but it goes away when I use the 3-prong adapter (ie 2+ground) adapter.
This is happening with the three prong as well as the two prong. It’s only really noticeable on the sensitive skin on the underside of my wrists.
I get the same thing with my Mac Book Pro. My power lead is showing exposed wiring near the bit that connects into the computer itself though not sure if that wiring is actually carrying current. Those Apple leads are terrible.
I’m planning on calling their support tomorrow and I’ll see if I can get a replacement power adapter. The fact it won’t charge the battery when plugged in a certain way would suggest there’s something wrong with it.
Or, worse, a problem with the connector on the laptop itself. Depending on how its set up, that repair can be anywhere from $20 to over $100. I hope you are still under warranty, if it is the more expensive case (i.e. directly connected to the motherboard).
I’ve only had it for a couple of weeks.
It might not be an electrical tingle, it might be a vibration caused by the 50Hz (or 60Hz depending on your location) AC.
I have an iPod dock like this. When the iPod is docked and charging, touching it produces a tingling sensation, but I’m pretty sure it’s just a mechanical vibration, because touching non-metal parts of the iPod produce the same effect. It definitely feels electrical, but I don’t think it is.
If it’s like any power adapter I have seen in recent days, the output is DC voltage, probably under 25VDC. You are not getting this tingling from the adapter. I heavily suspect some neuropathy in your hand that has developed from heavy use, such as a mouse or mouse pad or other work you do repeatedly. It might even be the early signs of carpal tunnel syndrome, but I am not a doctor.
I’d say the outlet itself isn’t grounded. I’m in an old house with knob and tube wiring, which doesn’t have a ground plug built into it. I can plug my TV into it just fine, but anything that needs three prongs (like the HTPC) will ground out if I try to plug coax cable into it.
What I experience when using the 2-prong adapter is difficult to explain: if I drag a finger across the metal surface of the laptop I will experience a sort of “vibratory friction”. This is absent if the laptop is on battery power or a 3-prong outlet. It could be described as a tingling sensation.
16.5V DC according to Wikipedia. So perhaps it is due to vibrations as suggested by Colophon and iamnotbatman. I doubt it being a neurological problem as I’ve had that kind of problem before and it felt different. It’s so subtle that I’m beginning to think I’m imagining it.
The Macbook connectors are magnetic breakaway, so they can be removed without any real “jerk.” Get your hands into position so you can feel the phenomenon, then have someone else pull the connector off and see if it stops.
This is caused by a Common-mode noise suppression capacitor in the power supply. This capacitor connects the primary side of the power supply to the secondary side, through a very small capacitance. It causes a very small amount of leakage voltage, which you can feel it the case is ungrounded.
This skin effect annoys me very much.
I’m going to cut-off that capacitor from my power adapter.
beowulff, do you know how to locate this capacitor?
Don’t do it.
Not only do you risk destroying the power supply, but you also risk damaging the computer or yourself!
Those power supplies are not made to be serviced- they are ultrasonically welded together, and have to be cut apart to open. Even Apple doesn’t repair them.
You might want to try a different power supply- some third-party ones may not bother you as much.
There is a video of how to open a power adapter: How to repair an Apple MacBook power supply (MagSafe) - YouTube
Seems not to be a rocket science. And I’m an electrical engineer.
There is a risk everywhere, but if this capacitor is just an EMI reducer, I prefer to throw it away and work comfortably.
Please make a video. For science.