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barebackbadger8
Jan 12, 2013, 06:16 PM
Noticed this for a while now, when my macbook air is fully charged or near full the screen lid and trackpad area feels like electricity is running through it
Now i never get this when using the long cable but only when i use little plug on the charger.... Could there be a fault with my macbook air or just the little plug?



kage207
Jan 12, 2013, 06:19 PM
Noticed this for a while now, when my macbook air is fully charged or near full the screen lid and trackpad area feels like electricity is running through it
Now i never get this when using the long cable but only when i use little plug on the charger.... Could there be a fault with my macbook air or just the little plug?
Uh, I never feel anything like that.

micrors4racer
Jan 12, 2013, 08:27 PM
Have you checked if it does it even when not fully charged? Is it a buzzing feeling? I have noticed this on my Air and Mac Mini. I also tried it at the laptops at the store. The buzzing feeling is coming from the texture of the metal and has nothing to do with electricity. It doesn't always happen but its pretty weird when it does. You really have to try and feel for it while softly running your fingers along the metal.

I think your hands/climate have to be pretty dry for it to happen but I have noticed it many times. Probing the metal with a multimeter showed that it has no residual voltage so it came to the conclusion that the feeling is caused by your skin and the texture of the metal.

maxosx
Jan 12, 2013, 08:31 PM
The buzzing feeling is coming from the texture of the metal and has nothing to do with electricity.

I'd like to see you post a link to verify this please.

Thanks

BeeJee
Jan 12, 2013, 08:42 PM
The long cable is grounded. The stubby insert is not so there's a greater chance of shock. I always use the grounded cable however, I let my sister borrow my charger so I put the stubby on. She left her computer plugged in on the sofa and when I picked it up it shocked the **** out of me. This is how I know that's the cause. Use the long cable or maybe a surge protector since that would be grounded.

micrors4racer
Jan 12, 2013, 08:50 PM
I'd like to see you post a link to verify this please.

Thanks

I observed it my self and at the Macs at the store. Theres no way a bunch of macs would be leaking current through their cases. And the fact that it happens on both my 2 Airs and Mac Mini shows that it the feeling is from the interaction of your skin with the metal. Using a volt meter on the case would also show if it has current running through it but it does not. If you try it out on your mac it might happen. I notice it happens alot easier on the areas near the keyboard on my air.

It maybe a random occurrence because of the way the metal is bead blasted and then anodized so some macs might have it more than others.

If you google it there are alot of threads.
https://www.google.com/webhp?hl=en&tab=ww#hl=en&sugexp=les%3B&gs_rn=1&gs_ri=hp&tok=fpW3inIRJHdQlw2OYkcl6g&cp=6&gs_id=l&xhr=t&q=mac+tingling+feeling&pf=p&safe=off&tbo=d&output=search&sclient=psy-ab&oq=mac+ti&gs_l=&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.1357700187,d.b2U&fp=7dca8a2ea6a13f68&biw=2316&bih=1251

https://www.google.com/webhp?hl=en&tab=ww#hl=en&safe=off&tbo=d&biw=2316&bih=1251&sclient=psy-ab&q=mac+vibrating+feeling&oq=mac+vibrating+feeling&gs_l=serp.3...25850.28578.0.28682.11.9.1.0.0.3.538.1766.0j4j0j2j0j1.7.0.les%3B..0.0...1c.1.IvWw02yJt YY&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&fp=7dca8a2ea6a13f68

There are threads that discuss actual earthing issues with power which is an actual problem with some Macs but more often what happens is what I previously described.

A quote from the apple community forums
reirei norwich
Re: Vibration (tingling) sensation on the Mac Book Pro
May 12, 2010 5:03 AM (in response to jojozep73)
Im not sure if this what the rest of you are talking about. But the tingly feeling you get when you run your finger along your palm rest (for example) has nothing to do with power but is merely the friction between your skin and the engineered aluminum surface being overcome. you'll feel it on any engineered aluminum block! on titanium blocks its worse..

A thread talking about it
https://discussions.apple.com/thread/2732288?start=0&tstart=0

Many people experience an issue with the ground but other people notice that the vibrating/buzzing feeling doesn't go away with switching to the 3 prong plug. The feeling only appears when your hand moves across the surface but not if you keep it in one place. This leads me to believe it is the surface of the metal.

iMacC2D
Jan 13, 2013, 04:57 AM
The Duckhead adapter, as opposed to the longer AC cable, does not have the third grounding pin and therefore doesn't earth the case of static electricity. If you look at each adapter where it connectors to the power brick, you can see it slides in over a metal post to lock it in. The cable version has metal rails inside the portion that slides over this post that touch that grounding post. The smaller, duckhead adapter does not.

https://discussions.apple.com/___sbsstatic___/migration-images/177/17764390-1.jpg

http://i50.tinypic.com/91cpa9.jpg

In the first image you can see the power adapter with metal center post on the right, and a duckhead adapter on the left. Inside the channel that slides over the post on the power adapter, there is nothing but white plastic. However in the second image, with the power cable, you can see shiny metal slide rails inside the channel that contact that post and ground the computers case when connected. (Click each to zoom.)

It's an incredibly common issue across aluminium-bodied Apple computers. I have these come in every few days. Swap to the cable and the issue goes away.

If it doesn't, I look to the power adapter next, and then the grounding in the building it's used with.

Barche
Jan 13, 2013, 07:05 AM
Many people experience an issue with the ground but other people notice that the vibrating/buzzing feeling doesn't go away with switching to the 3 prong plug. The feeling only appears when your hand moves across the surface but not if you keep it in one place. This leads me to believe it is the surface of the metal.

I have the same issue with the 2-prong plug only. I did some tests, and conclude that this can only be related to a grounding phenomenon, not the metal surface:
- testing between any two points on the surface of the laptop with the voltmeter in "beep" mode comes up negative, suggesting just holding the voltmeter probe on the surface of the laptop is not a good method to measure
- With the 2 prong plug, I see 0.1V difference between the house ground and the end of the magsafe plug. With the 3-prong this goes away
- moving my hand over the surface only produces a tingling sensation when the 2-prong connector is used AND when I am not insulating myself from the floor. This clearly indicates some small current flowing from the laptop through me to the floor.

The differences in comments on this issue can be explained:
- the amount of leakage probably varies from laptop to laptop
- some people well be bare-footed, others always wearing shoes, resulting in much better insulation from the floor, which may be enough to eliminate the problem
- even when using 3-prong cables, there might be a fault with the cable, the adapter, an extension cord or the grounding of the socket itself
- some people will be more sensitive to this sensation than others

I'm just disappointed that there's no grounded short plug for the adapter.

barebackbadger8
Jan 13, 2013, 10:28 AM
I have even tried the 'duckhead' (never known it called that before lol) from my ipad and it still does the same so thats what made me believe there was a problem with the duckhead build/lack of earth etc
As soon as i unplug it the static i feel immediately disappears so its definitely that

Not sure if making a genius appointment is worth it, i have never once had a problem with the long cable (i always charge the macbook in the same electric socket on wall)

I have applecare (got well over 2 years left on it) so i might just see how it goes, just hope if i do use the duckhead plug that it doesnt damage the MBA.

justperry
Jan 13, 2013, 10:44 AM
The problem here is that the Common wire is not 0 Volts, in many countries (mine as well) the Common wire is connected to the Ground pin at the entrance of the house.
When I am there I don't have the problem, yet here in Asia I do have this.
If I disconnect the charger's connector from my Laptop it's also gone.

There is a small charge/Voltage on the common wire, this is also connected to the body of the laptop, that's the reason you feel it, it is not dangerous though.

If I lift my feet from the ground it's also gone.