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

Collin973

macrumors 6502
Original poster
Mar 29, 2006
259
0
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!
 

Collin973

macrumors 6502
Original poster
Mar 29, 2006
259
0
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."
 

gr8tfly

macrumors 603
Oct 29, 2006
5,298
48
~119W 34N
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

macrumors member
Jul 2, 2007
67
0
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
 

weckart

macrumors 601
Nov 7, 2004
4,752
1,789
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.
 

kolax

macrumors G3
Mar 20, 2007
9,186
115
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

macrumors 6502a
Jan 9, 2007
690
0
Houston, TX
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.

macrumors 65816
Mar 22, 2006
1,459
0
London
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
 

kolax

macrumors G3
Mar 20, 2007
9,186
115
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

macrumors 604
May 21, 2007
7,849
36
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.
 

MaddieBrad

macrumors regular
Apr 8, 2007
188
0
New York City
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

macrumors 65816
Sep 29, 2006
1,060
65
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

macrumors 6502
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

macrumors 6502
May 12, 2007
454
53
Philly
(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). North American convention, however, is to install with the ground pin down.
 

ab2650

macrumors 6502a
Jun 21, 2007
714
0
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

macrumors 603
Oct 29, 2006
5,298
48
~119W 34N
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.
 
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.