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  1. #21

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    Originally posted by Currawong@Nov 24 2005, 08:02 AM
    I'm confused about the grounding as well. Regardless if the cable has 3 pins on the wall-socket side, it still only has 2 pins on the power brick side, so i don't understand what different it makes.
    The third pin on the adapter end of the power cable is the "post" on the adapter. If you take the cable off, and look in the slot, you will see some silver contacts. The "Duckhead" as it's known, (the small 2 prong power connector) which is only 2 pin, doesn't have this feature.

    Perhaps in the US where the voltage is only 110, not 240, they don't have such an induction problem.
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  2. #22

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    I'd guess this has nothing to do with the Powerbook power circuits and is more than likely static charge buildup. Even AC to DC adapters that have 3 prongs rarely have any earth connection on the DC side, so I suspect using an extension cord has nothing to do with whether you get a tingle - more to do with the dryness of the environment where you use the 'book with and without the extension cord. (A mere few percent difference in humidity can make an enourmous difference.)

    This would more logically explain how some people have complained of a 'book being killed by this sort of zap, too.
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  3. #23

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    I agree with stevejay that this is more than likely a static build-up issue. Other explanations seem highly unlikely. Again, I concur that the dryness or otherwise of the atmopshere is a major effect. I experience this in a high altitude, very low humidity city, where my iBook was continually charged and zapping me every few minuites, and it also made the trackpad almost useless.

    Also, the laptop user themselves will charge themselves to different potentials depending on humidity, clothing, carpets or rugs, fabric on chairs, types of shoes, shuffling feet, moving about in chair etc. Building up a substantial static charge is very easy.

  4. #24

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    MacAid: I hadn't noticed that before, thanks.
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  5. #25

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    Originally posted by Mac Aid+Nov 24 2005, 08:32 AM--></div><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Mac Aid &#064; Nov 24 2005, 08:32 AM)</td></tr><tr><td id='QUOTE'> Perhaps in the US where the voltage is only 110, not 240, they don&#39;t have such an induction problem. [/b]

    Mate, how would induced current coming down the 12V cable from the power adapter be any different to the intended 12V current? The issue here is a small amount of leakage current through the switching regulator circuit. An induced current would be isolated from the mains source, and therefore wouldn&#39;t give you a shock...

    BTW Half (or more? less? not sure on the specifics) the current coming through is &#39;induced&#39;, since that&#39;s these switching power supply designs are based around an inductor... :P

    If the leakage is caused by a resistor somewhere, then there would be half the amount of leakage current through your body when you were on 120V vs 240V. (110/120, you get the picture)




    This thread has some more info/speculation on this issue....



    <!--QuoteBegin-Mac Aid
    @Nov 23 2005, 10:30 PM
    What makes you say it&#39;s not double insulated? The shock is from induced current, not leakage of 240v [/quote]
    Well it could be, but normally devices have a logo which looks like two concentric squares to indicate double insulation (there&#39;s international regulations on this from memory) - check any plug packs you have lying around and you&#39;ll see what I&#39;m talking about.

    In fact, I&#39;ll do your homework for you: Click here for what Wikipedia has to say
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  6. #26

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    Hi all just wondering if anybody else was occasionlly getting a shock from the case of the powerbook? Seems to have stopped now but is a weird feeling when it happens&#33;

  7. #27

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    Never got a shock or zap as such. But when its plugged into power, and run my hand or finger over the powerbook casing i feel a little bit of a vibration or just a sensation.

    I think its because the case isnt grounded properly.

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  8. #28

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    Use the longer power cord instead of the beak.

  9. #29

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    Originally posted by Bahamut@Mar 11 2006, 03:00 PM
    Use the longer power cord instead of the beak.
    I don&#39;t think that solves the problem. I&#39;ve always used the long cord and I get the same tingly sensation
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  10. #30

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    yep mine does the same it is worse if you have something that earths you like an electric guitar in your hands,when I&#39;m doing some recording on my PB it sets up the worst buzz through my amplifier
    if you touch the computer and guitar at the same time
    :blink:

  11. #31

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    I&#39;ve had the same problem and I think I know why it&#39;s happening.

    My story goes like this:
    Sitting in my shorts with the powerbook partially on my bare leg with it plugged in. All of a sudden I get a little sensation. I couldnt figure it out for the longest time. I finally realized what I was doing. I was putting my foot up on my windoze tower which is made out of a metal as well, and because both the PowerBook casing and the tower casing are grunded, I was essentially providing a link between the two.

    No upon reflection, the specifics of that story don&#39;t seem completely correct, but that was the problem nonetheless.

    I&#39;d watch out for any electrical contacts you&#39;re getting near, be it positive or negative, because your body is a good conductor.

    At least, thats my two cents...

  12. #32

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    I had a some issues with my Ti book in certain weather conditions running on mains power. I would get the occasional shocks as well as the sensation of a current running through the area to the left of the trackpad. Never did solve the problem. My Al powerbook has no issues at all.
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  13. #33
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    There was an issue with certain PBs passing electrical current to it&#39;s owner, there was a fix, not sure what is, will look into. Think may have to take to shop.
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  14. #34

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    Mine does it all the time. Can&#39;t put it down to anything in particular. Asked The bloke from the Rockhampton store about this once and he said it had something to do with my watch.

  15. #35

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    You can do something cool (or dangerous, whichever way you look at it) with the iBook&#39;s power cable.

    One night I was holding the power cable by the metal tip (the bit that goes into the &#39;Book) whilst it was plugged in to the wall, and to my surprise the light on the end of the cable actually came on. Very dimly, but you could tell it was on. I was like "whoa". Then I realised I was also touching my metal bedside lamp, which was on.

    First I was all "cool&#33;", then I realised how dangerous(?) this could be&#33;






  16. #36

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    yeah there was a thread about this last year. for the vast majority (self included) the PB gave us a shock if we used the ungrounded power lead - the one with only a 2 prong plug but as soon as we switch to the longer lead with the 3 prong plug the problem disappeared.

    apple know about it but seem unconcerned so i guess the issue must be on the low voltage side or they would not risk it.

  17. #37

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    Use the 3-prong AC cord, not the 2-prong plug. The actual shock isn&#39;t dangerous - but it is less safe statistically then when using a 3-prong (earthed) adaptor. I&#39;m studying Electrical Engineering btw.

    If you use the 2-prong one and your power supply decides to melt, it won&#39;t set off your RCD, whereas the 3-prong one will. That said, if you have your laptop plugged into other things that are earthed when you are at home (monitors/speakers etc) then you can safely use the 2-prong adaptor, since your laptop will be earthed through the other devices. It may even get rid of an annoying earth loop that&#39;s causing hum in your speakers.
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  18. #38

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    My new MacBook Pro has the same problem, again isolated to the unearthed 2-pin plug, and again independent of location. It *isn&#39;t* static buildup, because it&#39;s a continuous tingling sensation whenever you touch the laptop. And it isn&#39;t dangerous, because it&#39;s totally isolated from 240V. The 240V is only in the power brick -- the laptop only gets 28V I think.

    The solution is not to use the 2-pin plug, but I keep the 3-pin long cable plugged in behind my desk at home, and the 2-pin plug in my laptop bag for use at Uni etc. because it&#39;s a big hassle to dig around underneath the desk every time I take my laptop with me and then again when I get home.

    Does anyone know where I can source another 3-pin long cable? I was previously using the one from my old Powerbook G4 but can&#39;t anymore since I&#39;ve lent it to my mum.
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