12" powerbooks so hot - there's current on the case

peve · February 20, 2003 4:25PM

today a customer returned his 12" pb and told me: "there is electricity on the case".

i couldn't believe it and plugged it in.

he was right! there was a small amount of voltage on the case.

pb only with battery: none

pb with power adapter and the cable with grounding: none

pb with power adapter and the plug without grounding: 7.33v voltage on the screws of the case

looks like apple (and me) are heading for trouble!

to sell something that draws electricity in switzerland there are very tough test's to pass.

i have no idea how apple got trough with this!

applenut · February 20, 2003 4:30PM

isnt that why they have a grounding plug?

murbot · February 20, 2003 4:33PM

Yeah, this is the first we've heard of it... but they all must do it.

heh heh

peve · February 20, 2003 4:44PM

sure they do have a grounded cable.

but the fact that there is a non-grounded cable in the box leads to people that use it.

this is a "no-no" where i live.

(ok, i know that the swiss people tend to be over-secure)

paul · February 20, 2003 5:33PM

there is a grounded PB adapter?

aquatic · February 20, 2003 5:35PM

All of them do this? How do we fix it?

peve · February 20, 2003 5:36PM

the one's sold in switzerland do.

paul · February 20, 2003 5:37PM

anyone have a pic?

peve · February 20, 2003 5:40PM

to solve the problem: use the grounded cable!

but i think there will be discusstion's between apple and the empa (place where swiss electronic devices get tested... bevor they get sold).

peve · February 20, 2003 5:56PM

shetline · February 20, 2003 9:47PM

[quote]Originally posted by peve:

today a customer returned his 12" pb and told me: "there is electricity on the case".

i couldn't believe it and plugged it in.

he was right! there was a small amount of voltage on the case.!<hr></blockquote>

When you say "there is electricity on the case", you're saying there's a voltage potential on the case relative to what? If I touch one probe from my voltmeter to the case, then to what do I touch other probe where to see the voltage you speak of?

Most cars are negatively grounded, so there's "electricity on the chassis" relative to the positive battery terminal. This is normal. It's quite likely that the PB case is a negative ground relative to various internal voltages (+12, +5, +3.3... not sure exactly what the PB uses).

[ 02-20-2003: Message edited by: shetline ]

a@ron · February 20, 2003 9:51PM

Hey its the current that can kill you, voltage on the other hand does not do much at low current. For instance, a Macroshock begins to happen at 1A when you feel it tingle. So if this voltage of 7 V was lower then 1 A it wouldnt even be preceptiable to most normal people, there are some wierdos out there though.

A@ron

icruise · February 20, 2003 9:53PM

I've heard a lot of complaints about the tibook having the same issue, so it's not new to the Aluminum books. I can feel a very slight charge, almost like a subtle vibration, if I run the backs of my fingers lightly along the palmrest of my 12" book, but nothing if I just touch it. Doesn't bother me at all. Of course if there were some sort of side effect, it would be different.

n a d n e r b · February 21, 2003 12:33AM

I don't think it's a problem. I've licked 9v batteries a few times and nothing happened to me.

I don't think it's a problem. I've licked 9v batteries a few times and nothing happened to me.

I don't think it's a problem. I've licked 9v batteries a few times and nothing happened to me.

I..... <img src="confused.gif" border="0">

spotcatbug · February 21, 2003 7:36AM

[quote]Originally posted by Paul:

there is a grounded PB adapter?<hr></blockquote>

My old PowerBook 1400 has a grounded power brick (three prongs into the wall, three into the brick). My new iBook's brick is not grounded (two prongs).

I wonder why the change, and whether something like that should be grounded.

costique · February 21, 2003 7:43AM

Our best evidence by far is Matsu. If he's still alive, laptops rule. If not...

Matsu, are you alive?

matsu · February 21, 2003 7:54AM

But barely. hahaha

Actually, I've got to say that this and other boards had me very worried about the potential heat. The hotest my book has gotten so far is luke warm while playing a DVD. As for the fan, it's very quiet to me, and doesn't come on much. Heat/fan? Not an issue. Electric shock? Not yet.

[ 02-21-2003: Message edited by: Matsu ]

costique · February 21, 2003 8:04AM

Matsu-u-u-uuu. Alive. How good to know it in these dangerous times when PowerBooks are too hot and poor laptop owners are exterminated with electric shock. :eek:

fawkes · February 21, 2003 8:04AM

The case is almost certainly connected to chassis ground, which is likely directly connected or capacitively coupled to signal ground on the circuit boards. Aluminum (or Aluminium for my UK friends) makes a wonderful EMI shield and the powerbooks would not earn UL or FCC approval if the case were not grounded (too much radio emissions). I just spent two weeks working to get my latest project to pass in our EMI test chamber--but it just passed in the UL labs yesterday!!!

Are you measuring voltage across the screws or between the screw and something else (neutral/ground of the wall outlet)? If there is any transformer isolation in the power supply brick, a small voltage between the case and neutral isn't so odd. Unless there is a short in the powerbook onto the case, it is *highly* unlikely that this voltage is a problem. Just because there is a voltage there doesn't mean that enough current can be developed to be felt, let alone injure. I=V/R will only hold true if whatever is supplying the current is capable of reaching the theoretical result of Ohm's law.

You build up several *thousand* volts just shuffling across the carpet, but the spark when you touch something represents a miniscule amount of current because the charge on your body is so small that a large current can't be delivered.

If you see a voltage across two screws, hold a wire across those screws and then measure the voltage again. If it is gone, then a bit of a charge just built up somewhere. If the PB goes up in a puff of smoke, then maybe there IS a problem there!

I'd be rather surprised if there was a voltage across two screws since the whole case is conductive and of very low resistance; there *shouldn't* be a voltage across it!

alcimedes · February 21, 2003 9:05AM

there's a really easy way to test this. if you have an open/recent cut on a finger, stick that open cut on the PB. if you feel pain, there's current. if you don't, there isn't.

voltage over exposed nerves really hurts.

i'm 99% sure neither the TiBook or 12" PB's have a problem with this though.

peve · February 21, 2003 1:10PM

[quote]shetline:

When you say "there is electricity on the case", you're saying there's a voltage potential on the case relative to what?<hr></blockquote>

read carefully.

i didn't say "electricity" - the customer did

[quote]shetline:

If I touch one probe from my voltmeter to the case, then to what do I touch other probe where to see the voltage you speak of?<hr></blockquote>

one probe to case (screws) and one to ground.

otherwise you can't messure.

[quote]icruise:

I've heard a lot of complaints about the tibook having the same issue, so it's not new to the Aluminum books.<hr></blockquote>

yeah? i never saw that issue with 15" pb's.

[quote]icruise:

Doesn't bother me at all. Of course if there were some sort of side effect, it would be differen<hr></blockquote>

dosn't bother me to.

it's 7.x v and almost no a.

that will never harm anybody.

but if a customer feels something he will bring me the pb back. customers complain a lot about stuff that isn't really importend.

[quote]Fawkes:

I'd be rather surprised if there was a voltage across two screws since the whole case is conductive and of very low resistance; there *shouldn't* be a voltage across it!<hr></blockquote>

like i said:

there is voltage between screw and ground.

if there was voltage between two screws, that would be a nightmare!

i'll repeat myself:

this will not harm anyone - it's just odd and customers get scared.

it just shouldn't happen with a electronic device in a metal case.

since the empa (swiss electronic-control-department) should prevent things like that i wonder how apple got through with this.

imho:

use the f***ing grounded cable or live with it.

12" powerbooks so hot - there's current on the case

Comments