Electric shocks from powerbook 12"
 

Hi All,

I just realised today that my powerbook G4 is giving me tiny zaps on my hands depending on where I touch the powerbook. This only occurs when it is plugged in to the main power supply. If I touch the very edge it feels like a pin prick - ouch! Running my fingers over the flat metal areas next to the track pad feels weird - as though the surface were made of velvet.

I have read other reports on the net about this but thought it was sorted out - obviously not. Does Apple fix this problem or do they just say it's normal and has to be put up with? Not happy about this.

S

My 12" has given various shocks, including the 'velvet' feeling. However, I can't get it to do it anymore. It used to be if I touched a metal surface at the same time as touching the case I would notice it.

I have a highly sensitive electrical screwdriver (cheapo thing) but its brilliant at detecting any amount of charge (for some weird reason). It shows a charge in the case when its plugged in, but when its unplugged there is no charge.

A simple way to prove there is a circuit is to hold the power plug (end that goes into the powerbook) by the outer metal contact and touch the case. Mine glows a weak green.

-- iNemo

Edit - And if you touch the case and the pin in the middle of the power plug, it glows a very weak orange.

Your Mac Power supply should be completely isolated from the line. If you're getting AC current (that tingly feeling) from the case, your power supply must be replaced. If it's still under warranty, contact Apple about a replacement. If you're out of warranty, still check with Apple about possible recalls. If not, you'll have to replace the supply.

By power supply do you mean the white power brick?

If so why do I get the current with my power supply, the power supply that came with my dads 15" Albook, The power supply off his girlfriends 15" Albook also causes the charge to be there in the case.

check your house wiring
 

You might also have a problem with your wiring. The hot-side and ground side of the wall socket may be mis-wired.

You are forming a circuit to ground via your body. I would be cautious about this; it can actually be very dangerous. Does it do this on all plugs in your house? If not, you may have the neutral and hot reversed on the plug(s) where it does happen.

I have had it on various power supplies as previously mentioned. In different locations as well. Including a University with a checked power supply. And that is on at least three different powerbooks (admittedly only one of them is a recent one, the rest are 6 months + old.)

-- iNemo

Same here - no matter where I plug it in be it at home or the university, it still has this "live" feeling. I'm taking it to Apple tomorrow. I'll post the result here.

S

I imagine it's possible that the Mac itself has a DC/DC switching power supply within. This should be totally isolated from the case though. If so, we're dealing with fairly high voltage, but such low current that it couldn't possible injure you. It's current that kills… I would test this with a good/sensitive digital meter, testing the two points that you're in contact with when you feel the tingle.

I have a 15 Titanium PB thats does the same, AT ANY LOCATION when plugged into the mains. I look forward to your post after you call Apple. ;)

I also had this problem on my PBook/12"/867. It was very tingly when I ran my fingers over the areas to the left and right of the trackpad. I sold my PBook a while ago and got a 15" version. I haven't experienced this problem on the new PBook, so perhaps Apple fixed it? Either way, I will also be interested in your phone call to Apple...

It must, to power the flourescent tubes for the display. As far as I know those still require rather high voltage.

As it might not be obvious:

If you use the cable-connection instead of the snap-on-connector directly on the power supply, you get a grounded connection (if the outlet you use is wired correctly).

That should solve the "tickle"-issue, which is probably due to floating ground.

That sounds like it's worth a try. However, I've already taken the pbook to Apple service here in Sydney and they are looking at it now. They said they had seen it before and it wasn't normal. I should get the full scoop on this in a few more days. Will keep you all posted.

Scott

The 3 prong cord that the power supply uses does not use the ground prong. It does polarize the other two though. But, like I said, the power supply should be totally isolated from the line, and wouldn't cause a "tingly" sensation. More like a "buzzing" at 60Hz. Painful too, since it would be 120v (rather low voltage comparatively) and high current.

My Sixpenceworth
 

Well, I had that on my 12 inch 1Ghz Powerbook AND my 17 inch. I have just sold the 12 inch.

I just bought a new iBook and that's fine because it has a plastic casing......until you touch the screen-release button! Then you get a rare tingle.

As with iNemo and others, it matters not where, or how, I plug into the power.

Looking forward to hearing what Apple say.
Cheers
Gavin

It might be summat to do with the earthing in my dads house as I can't get it to happen at home, but as soon as I plug into dads, its there. Mind you if you have a cut and you touch a certain point on his kitchen tap it gives you an electric shock.

Haven't noticed it for a while now, probably for about a day after this post started was the last time I noticed it. Coincidence?

-- iNemo

I probably would not have cared to correct.
But my multimeter can get mighty polemic at times and convinced me to post, let me quote it:

"...[some ramblings about how people get political leaders and 3 prong cords they merit deleted] (my multimeter and me are from "old Europe")...
The ground connector definitely +is+ connected to the recessed feather-contacts that clip onto the power supply."

It also suggests that iNemo should see the faulty electric installation gets fixed before it does more than just tingle...

Yeah i think he's waiting for the people he rents it off to get an electrician out to check it.

And it also happens at college (old building, but the wiring has to be to a standard, rite?) and at my mates house, which is about 15 years old and has had a full electrical check on it (kept on blowing RCJ? Units up. Turns out Powergen can't wire them in properly...).

Thank-you voldenuit. I stand corrected.

Hi folks,

Well I got my powerbook back today. In fact I had to go into the Apple repair centre to demonstrate the problem to the repairman! He was the size of brick s**thouse with fingers the size of sausages so couldn't feel anything. So another guy comes over and agrees with what I'm saying (velvet feel). The next thing we do is examine the power supply and here's the problem: If you use the short plug adapter, it is not grounded as stated earlier by Las Vegas. In fact, if you look inside the plug attachment, there is no metal on the inside of it. Now look at the inside of the corded plug. This one (in Australia anyway) has the ground pin on it and the metal inside the groove (for ground). As soon as I plugged in the grounded cable, the problem was gone. So the question is, why did Apple not ground the mini/travel plug for the power supply? A major oversight if you ask me. The Apple guy said to plug in a mouse if using the travel adapter...apparently it will ground it but haven't tried.

Scott