Noticed a "ribbed" feel to your mbp's aluminum?

[Collin973]

I've got one of the first C2D Macbook pros and I've noticed that (sometimes) when I move my hand across the palm rests that the aluminum feels ribbed and makes my hand vibrate. You need to apply light pressure and move your hands back and forth and you should feel it.

Does anyone else's do this or am I just special? It feels pretty cool and you'll notice if it happens. On mine, it also happens over the speaker grates. Give it a try and let me know!

[joekix]

it could be a light shock.

[Abstract]

Yep, noticed that on my old 12" PB. Even after 3 years of ownership, it was a pretty weird feeling.

[Collin973]

it could be a light shock.

Nope, I don't think it is. It's a continuous feeling and only seems to happen if my hands aren't just washed. I just took a shower and now I can't feel it, but 10 minutes ago I could. I think it has to do with the tiny crevasses between each ridge of your fingerprints and the microscope ribs in the aluminum. And when those crevasses has just the amount of oil/sweat/junk in between, they match up with the ridges to produce the feeling.

I've been shocked by a lot of things and this doesn't feel "electric."

[Nermal]

I know what you're talking about and I assumed it was the hard drive vibrating.

[mayoko185]

yeah I made a post (http://forums.macrumors.com/showthread.php?t=322417) about this a while back too. IMO it feels kinda cool :cool:

[RichL]

Isn't that....just...friction?

[gr8tfly]

Nope, I don't think it is. It's a continuous feeling and only seems to happen if my hands aren't just washed. I just took a shower and now I can't feel it, but 10 minutes ago I could. I think it has to do with the tiny crevasses between each ridge of your fingerprints and the microscope ribs in the aluminum. And when those crevasses has just the amount of oil/sweat/junk in between, they match up with the ridges to produce the feeling.

I've been shocked by a lot of things and this doesn't feel "electric."

I don't think that's what's causing it. It probably feels like there's something between you and the MBP's metal skin, but it vibrates. Leakage current (normally, very low) from a less than perfect grounding system in your a/c power wiring can feel like that. Changes in your skin's conductivity will affect how good a connection it is making with the metal skin.

Try using the 3-pronged a/c extension cable that shipped with your power supply.

[Dizzee]

yes all you are feeling is friction.
i just tried it out on my mbp, couldnt feel a thing, but then i washed my hands and i understand what you are saying.
deff not any type of electrical shock.
but it also is not because of microscopic ribs

[Cali_Man]

Yup, ribbed for your pleasure!

I guess now we finally know why there are so many problems with excessive thermal paste?

[PkennethV]

Yup. I used to get it on my 12" PowerBook, but not on my MBP. Thought it was kinda cool. No idea what it was though.

[weckart]

Good, I thought it was just me. It is particularly noticeable on my MBP just above the F7 key and sometimes along the palmrests. I think it might be a conductivity issue depending upon how greasy my fingertips are.

[Kilamite]

It is a static shock. It isn't a problem for UK users since we have a 3 pin plug system here - the 3rd pin being an earth wire.

Since we have an earth wire, any static electricity is taken away from the casing and down to the earth. I don't suffer from this problem at all.

Unless, I plug my MBP in by just using the power brick (not the chord extension). The UK adapter for the power brick doesn't use the earth wire, so I get the static shocks when using it.

Also, another way to replicate this problem is to run your MBP on battery and plug in an external hard drive. Most external hard drives can provide some sort of static (mine does anyway) and I get the same thing happening.

It's due to the case being metal. The beauty of the earth wire!

[anirban]

Does it happen only when connected to AC power? Or even when running off the battery?

Mine does leak out a tiny bit of current while on AC, and I do get that feeling over the metallic parts... but not when its running off the battery.

[Tom B.]

It is a static shock. It isn't a problem for UK users since we have a 3 pin plug system here - the 3rd pin being an earth wire.

I notice it on my 12" PowerBook, and I'm a UK user. I spent 5 minutes trying to work out how i still felt it, then i noticed the obvious...

I'm using a US 3rd party charger with an adapter plug on the end! :p

[Kilamite]

I notice it on my 12" PowerBook, and I'm a UK user. I spent 5 minutes trying to work out how i still felt it, then i noticed the obvious...

I'm using a US 3rd party charger with an adapter plug on the end! :p

Well if you are using a US charger then that won't have an earth wire will it? US plugs are 2 pins, UK are 3 pins.

[CalBoy]

Well if you are using a US charger then that won't have an earth wire will it? US plugs are 2 pins, UK are 3 pins.

Not true. I use the plug that has a grounder. We get a choice with Apple:cool: It's really more a matter of common sense to me.

[Tom B.]

Well if you are using a US charger then that won't have an earth wire will it? US plugs are 2 pins, UK are 3 pins.

Yeah, thats what I was implying.

[MaddieBrad]

Yup, ribbed for your pleasure!

I guess now we finally know why there are so many problems with excessive thermal paste?

HAhaha... I was scrolling through all the posts to see if anyone else posted "for your pleasure" It was the first thing that came to my mind when reading the thread title.

LOL

[jamesarm97]

Yeah, thats what I was implying.

Most US stuff has been 3 pin for a while. It is the cheap extension cords that are 2 pins a lot. (off topic): I had a co-worker that was very anal and always pointed out that most of the US sockets are installed upside down. The ground pin according to him was supposed to be on the top so if something metal 'fell on it' it would hit the ground first. I have only seen a few places where they are installed that way. Most have the two pins on the top and the ground on the bottom.

[10-Dee-Q]

it's a static (electricity left over) or something, i don't know what the exact name for it
but it's almost the same feeling when you touch the screen of normal Television (tubes one) only on the MBP is milder.

in my country the electric socket only have 2 prongs without negative ground tha'ts why if i touch MBP without wearing shoe or sandals the static become very strong , almost like you are electrocuted.

that's why i sold of my MBP and bought Black MB instead :P

[VideoFreek]

(off topic): I had a co-worker that was very anal and always pointed out that most of the US sockets are installed upside down. The ground pin according to him was supposed to be on the top so if something metal 'fell on it' it would hit the ground first. I have only seen a few places where they are installed that way. Most have the two pins on the top and the ground on the bottom.Staying off-topic a moment longer in order to clear up some misinformation: your co-worker is wrong. NEMA 5-15 and 5-20 wall receptacles can be found installed in several orientations. Neither NEMA, U.S. National Electrical Code nor Canadian Electrical Code specify a preferred orientation. (see more info here (http://en.wikipedia.org/wiki/NEMA_connector)). North American convention, however, is to install with the ground pin down.

[ab2650]

I've had this experience too and just assumed it was hard drive vibration. I haven't tested to see if it makes a difference when my hands are washed or if the MBP is running on grounded AC, ungrounded AC, or battery.

If it is indeed electrical, shouldn't a multimeter pick it up? My meter is at work so I plan to test this come Monday, but if anyone else has one, I'd be interested to know their results.

The more you know(tm).
-ab

[gr8tfly]

It's not static electricity. That's the stuff that creates a spark when it discharges through you. It's tens of thousands of volts, but very low current.

A bit of clarification on the Apple a/c supply: Although the "hide-away" plug is two-prong, the extension that can be used in its place is 3-prong. The grounding pin (3rd conductor) connects to the power supply's ground (and your MBP's) through the metal button the adapter slides onto.

[rijiMacDij]

My powerbook does it, but my new SR MBP 17 does it way more! In support of the static shock theory I unplugged my MagSafe power cord and it stopped instantly, plugged back in and away she goes!

Weirdly, after resting my acrylic wool clad forearms on the palm rests for a few minutes it has stopped while being plugged in!

Who cares, as long as my girlfriend doesn't try using it as a vibrator.

[Caezar]

I posted a message on this forum a year back. I realized that the vibration you feel is because your body conducts electric current.

You can do an easy experiment:
- Rub your notebook barefoot. You will feel the vibration.
- Wear a pair of shoes with rubber soles and rub your notebook. You should no longer feel the vibration. That's because rubber does not let electricity pass through.

The bottom line: nothing to worry about.

[gr8tfly]

I posted a message on this forum a year back. I realized that the vibration you feel is because your body conducts electric current.

You can do an easy experiment:
- Rub your notebook barefoot. You will feel the vibration.
- Wear a pair of shoes with rubber soles and rub your notebook. You should no longer feel the vibration. That's because rubber does not let electricity pass through.

The bottom line: nothing to worry about.

Which also points to a grounding problem. As mentioned here (and other threads), try using the 3-prong, grounded extension. If it's still there and becomes annoying and/or uncomfortable, it might require a call to an electrician. Otherwise, as Caezar posted - "nothing to worry about".

[Kilamite]

Not true. I use the plug that has a grounder. We get a choice with Apple:cool: It's really more a matter of common sense to me.

Uh...?

I'm British so not fully aware of American style plugs, but as far as I know they are only two pins and don't offer support for an earth wire.

That was the point in my post.

[gr8tfly]

Uh...?

I'm British so not fully aware of American style plugs, but as far as I know they are only two pins and don't offer support for an earth wire.

That was the point in my post.

I believe grounded outlets have been a building code requirement for probably 50 years or longer, depending on the location (city/county/state).

Depending on the particular device, it might or might not have a ground (3 prong). Standard computer and electronic equipment a/c cords (the squarish female plug that goes in the back of equipment) are grounded. Many "wall-wart" a/c adapters do not (2-prong).

[CalBoy]

Uh...?

I'm British so not fully aware of American style plugs, but as far as I know they are only two pins and don't offer support for an earth wire.

That was the point in my post.

American outlets have had a grounder for quite some time. Most heavy appliances have a grounder (blenders, computers, etc). Perhaps it's time to break that false paradigm of yours;)

[Kilamite]

American outlets have had a grounder for quite some time. Most heavy appliances have a grounder (blenders, computers, etc). Perhaps it's time to break that false paradigm of yours;)

Thanks for the advice, I'll dump it with the rest. I already said I'm not familiar with American plugs - I was only after an explanation not an instruction.

[CalBoy]

Thanks for the advice, I'll dump it with the rest. I already said I'm not familiar with American plugs - I was only after an explanation not an instruction.

No need for sarcasm. Your first post was written as if you knew American outlets thoroughly. The paradigm I was refering to was the one that implies safety standards are behind in the US (though in certain ways, they still are).

[Kilamite]

No need for sarcasm. Your first post was written as if you knew American outlets thoroughly. The paradigm I was refering to was the one that implies safety standards are behind in the US (though in certain ways, they still are).

Alright, sorry. I'm still confused by the matter though (or that I've missed a direct explanation) - 2 pin U.S. plugs; do they support earthing?

[gr8tfly]

Alright, sorry. I'm still confused by the matter though (or that I've missed a direct explanation) - 2 pin U.S. plugs; do they support earthing?

2-prong would be "hot" and "neutral", but no earth ground.

[CalBoy]

Alright, sorry. I'm still confused by the matter though (or that I've missed a direct explanation) - 2 pin U.S. plugs; do they support earthing?

No, 2 pin plugs do not support grounding (what we call it in the US). Common items do not have a grounder (like my iPod wall charger), but appliances with a higher wattage will have a grounder (like a blender or leaf blower). Like you said, the MBP power brick comes with two plugs: one with a grounder, and one without. I always use the one with a grounder, because it's common sense.

[gr8tfly]

Another thought on the leakage current:

Sometimes, it can be reduced by reversing the plug. (turn it 180 degrees)

Grounding would still be the better solution, though.

[Kilamite]

No, 2 pin plugs do not support grounding (what we call it in the US). Common items do not have a grounder (like my iPod wall charger), but appliances with a higher wattage will have a grounder (like a blender or leaf blower). Like you said, the MBP power brick comes with two plugs: one with a grounder, and one without. I always use the one with a grounder, because it's common sense.

Sorry for being ignorant but that's where the confusion is - there is 3 pin plugs in the U.S for things like a blender? So U.S. sockets support 2 and 3 pin plugs?

[CalBoy]

Sorry for being ignorant but that's where the confusion is - there is 3 pin plugs in the U.S for things like a blender? So U.S. sockets support 2 and 3 pin plugs?

Yes, US outlets support both 2 and 3 pin plugs. I can plug the blender into any outlet in the house, and I can do the same with something as small as my iPod charger.

[gr8tfly]

Sorry for being ignorant but that's where the confusion is - there is 3 pin plugs in the U.S for things like a blender? So U.S. sockets support 2 and 3 pin plugs?

Here's a picture: NEMA 5-15 Outlet 120V/15A (http://en.wikipedia.org/wiki/Image:P2050397.JPG)

The two top, rectangular, pins are compatible with any 2-prong, ungrounded, plugs. The ground pin is round, centered pin at bottom. (2 complete sockets in this example).

[ppc_michael]

Edit: Bah! gr8fly beat me to it.

An image to clear this American plug confusion up! :)

http://images.acclaimimages.com/_gallery/_SM/0001-0408-1013-2913_SM.jpg

This picture shows US power outlets with three prongs (left and right are standard, the hole at that bottom is the ground.) This also shows an appliance that is not grounded plugged in. But other appliances (computers, etc) have the third prong.

And hooray, I thought I was crazy for having the vibrations.

[Kilamite]

Ahh I understand now!

I've never been to the U.S and all the pictures I saw of appliances had only 2 pins, wasn't aware there was a 3 pin option. Is your sockets meant to look like a man screaming?

Thanks for clearing that up.

[CalBoy]

I've never been to the U.S and all the pictures I saw of appliances had only 2 pins, wasn't aware there was a 3 pin option. Is your sockets meant to look like a man screaming?

Thanks for clearing that up.


LOL we like to think of them as bunny faces. I'm glad I could help.

[gr8tfly]

Ahh I understand now!

I've never been to the U.S and all the pictures I saw of appliances had only 2 pins, wasn't aware there was a 3 pin option. Is your sockets meant to look like a man screaming?

Thanks for clearing that up.

I always thought it looked surprised. Kinda like when you have your fingers touching the prongs as you plug something in. :eek: (don't ask - I was very young.)

Glad to help, too.