Resolved Stray voltage running on 220/240V

Discussion in 'iMac' started by Kanunu, Sep 10, 2012.

  1. Kanunu, Sep 10, 2012
    Last edited: Sep 15, 2012

    Kanunu macrumors 6502

    Joined:
    Apr 18, 2009
    Location:
    Hawaii
    #1
    I brought my US purchased iMac to Vietnam after checking out posts here and on Apple's user group. I have a late 2010 so it is dual voltage. It seemed to runs OK at first but I seem to be having stray voltage sometimes on my keyboard (Apple USB) and on the outer edges of the monitor case. It is slight as I can usually only feel it if the back of my hand touches these places. It is also more on the edges.

    All electricity in my home is 220/240 Type C which is two round receptacle holes with no ground. My iMac is plugged into a splitter/adapter which can accept the ground prong but I am sure it does not connect to ground as there is none.

    I can buy a voltage step-down transformer here but I don't know if that solves the problem unless it connects the ground line to the neutral.

    Also I have developed an impending HDD crash situation as confirmed by Disc Utility.app. The empirical evidence that made me check Disc Utility was slow read times and an increase in "beachballing" and momentary freeze-ups. I read elsewhere that stray voltage could cause HDD failure. Could my current problem be caused by stray voltage? If so, I want to solve the voltage situation before changing out the drive.

    Any help would be very much appreciated.
     
  2. skinny*k macrumors regular

    Joined:
    Feb 21, 2011
    Location:
    California
    #2
    Kanunu, yours is an electrical problem, not a Mac problem.

    What you 'feel' is likely a static electricity build-up, and yes, that can damage equipment. Go to your local version of Radio Shack and pick up a 1/4 watt (or greater) 1 mega ohm resister (one-million ohms) and attach one end of it to a cold water pipe, or any metal object rising from deep in the ground, and connect the other end to a wire connected to your computer's ground. If you still have problems other than with the drive—which may not recover—consult a good electrician in your area.

    I don't know anything about the quality of electricity available to you; if it is poor, you will likely need a line conditioner to protect your electronics. Still, grounding is a good idea. It is a good idea, too, to touch a grounded surface before touching your computer; that way you don't discharge static electricity to it.

    I hope that this helps.
     
  3. plumosa macrumors regular

    plumosa

    Joined:
    Mar 17, 2007
    Location:
    Australia
    #3
    Is there any way you can charge it somewhere else where it can be grounded and just use the battery when at home? It's an imperfect solution but, depending on your usage, it might work.
     
  4. cyclotron451 macrumors regular

    cyclotron451

    Joined:
    Mar 16, 2005
    Location:
    Europe
    #4
    get a UPS

    When I worked in asia I found it was a great idea to use something like an APC BK650 UPS (uninterruptible power supply) between the 220V power outlet and the iMac. This will handle any small brownouts - dips & spikes in teh supply voltage which would otherwise stress the computer supply. Even if its a small UPS with only a 10 minute battery - this is long enough to switch the system off when there's an extended power outage. The biggest gain however is de-stressing the computer power supply, in rural or semi-ruaral areas and developing nations the "220/240Volt mains" has been found to carry many kilovolt (Yes +1000Volt) spikes - which over time break everything! With a small and cheap UPS you have to throw away a $100 component every few years instead of an $2000 iMac!

    The tickling/buzzing feeling on the iMac case is simply due to capacitive coupling/leakage from the 220V live to the case of the iMac, as there is no actual ground. The iMac PSU EMC - (electromagnetic compatibility) compliance components shunt/leak a small amount of the mains voltage - really nanoamps - and the computer case 'floats' at around half the supply voltage. (This can be a problem in medical electronics - hence why they have special leakage requirements)

    The idea of dispersing the leakage currents to a water pipe or similar through a resistor should work fine; This effect is extremely unlikely to have affected the HDD inside the iMac. hard disks just fail! We don't know when, but it's a 100% failure rate over time

    Consider using carbon copy cloner app and make an external USB/firewire bootable image hard-disk of your internal iMac HDD, so that you have another backup.
     
  5. Kanunu thread starter macrumors 6502

    Joined:
    Apr 18, 2009
    Location:
    Hawaii
    #5
    Thanks for ideas

    Thank you skinny*k. I had been thinking this is static rather than leakage as it is not continuous. I don't know how it affects things but all the floors are tile here.

    I am sure there is a place I could buy a resistor as you suggest but my own lack of knowledge and language obstacles would make finding it difficult. I am looking on Amazon at an anti static mat that the iMac can sit on. I had actually thought about a screw and wire in to the aluminum case but that was a little to radical for me. The mats are for electronic work and seem to have a wire lead. Some go to wrist band for doing fine work but some just attach to ground. Do you think one of these would work? My main problem will be finding a good ground as the plumbing is mostly all PVC.

    Unfortunately the workers at the local equivalents of Best Buy seem fairly clueless. I bought an HP inkjet and they insisted on hooking it up to one of their laptops to see if it worked. After about 10 minutes I lost patience with the salesman and had to show him how to print out the test sheet. Of course the quick setup sheet is graphical but he still did not get it. Fortunately the authorized Apple repair shop seems competent. I paid them a visit and they will replace my HDD for $25 US labor. The drive (1 TB Seagate) will be about $88 or I may use a 420GB Corsair SSD that will set me back $240. Either way not too bad overall. I will discuss the static situation with them when I take it in. There are a few techs there who speak excellent English.

    The electrical quality is rather poor here. Only had one brief outage so far but I think the voltage may vary. People here use line conditioners on their refrigerators. I had a large UPS while in the US but did not bring it as it was a) 110V and b) too heavy. The APC brand has an authorized reseller here and I need to get something there sooner rather than later.

    Sorry but it is an iMac. Don't want to sound sarcastic but notice which forum this is in. There have been a lot of times here when I wished it was a MBP or MacMini especially since I will need to box it up and move it by taxi to have it repaired.
     
  6. Kanunu thread starter macrumors 6502

    Joined:
    Apr 18, 2009
    Location:
    Hawaii
    #6
    My appreciation.

    cyclotron451: your suggestions actually came on as I was writing my last post. Thanks for the detail. You have boosted the urgency with which I feel I need that UPS. Even if it really is current leakage as you describe and not static charge, what do you think about the idea of the antistatic mat under the pedestal and keyboard leading to ground?

    I hope you are right about the HDD and it is just wear and tear. Apparently the Seagate model I have is prone to failure but mine is out of warranty as I did not buy Apple Care. Yes I do have CCC and have two scheduled backups every day, one to a desktop external and one to a portable. Apparently the problem reported by Disc Utility.app is mechanical and not just cross linked files or such. I did a dry run by booting to the clone, formatting my internal drive and moving the data back from the clone. The process worked fine and boosted my confidence in being able to safely restore to a new drive. Much easier than trying to work with a new Lion install and Time Machine. I had hoped that it might clear up the disk problems but it did not. One question I was planning to check on CCC forum is: Can I move my data from my 500GB clone to a 420GB SSD replacement? The data plus OS X is actually less than 150 GB as I keep videos on an external drive.

    I know it is another whole controversy but is extending HDD life an argument to turn off machines when not in use? I have usually let my unit sleep since I bought it and only shut it down when I was planning to be away for more than a few days. Is the drive still spinning at 7200 when the machine sleeps?
     
  7. cyclotron451 macrumors regular

    cyclotron451

    Joined:
    Mar 16, 2005
    Location:
    Europe
    #7
    Hi, Yes - I have my MacBook on an antistatic mat on my desk - a good antistatic mat is a dissipative resistor - so meets the suggestions of the previous poster - but unless you connect the antistatic mat actually to a reliable and safe 'earth' then you're just going to make your whole desk 'tingly' or slightly live! (My mats have the press-stud at the four corners and one of these goes to an earth bond point with a further 1 megaohm resistor inside which is plugged into the - helpfully - three point mains socket, L, N and E. The reason we keep mentioning mega-ohm resistors and even the resistive/dissipative electrostatic-discharge antistatic mats - is under fault conditions of the electrical system you don't want low resistance mains voltage suddenly appearing on your anti-static/anti-leakage systems)

    Have you considered just using the Apple wireless bluetooth mouse and keyboard and avoiding to touch your iMac as much as possible? wireless means no tingles! set it to sleep & wake-up automatically...?

    Glad you agree that a UPS is a 100% requirement - I just mentioned APC as I bought one of their domestic UPS for a low price and it's still doing the job fine after a decade. If you could find a local radio ham he'd be able to sort your leakage earth out for you.
     
  8. skinny*k macrumors regular

    Joined:
    Feb 21, 2011
    Location:
    California
    #8
    It isn't just carpets that generate static electricity; clothing and atmospheric conditions play in, too. The anti-static mat will have the resistor built-in; try to get one with 'snap-connectors' for extra connections. If you also get an extra anti-static wrist band, cut off the band and strip the wire, loosen one screw on the memory-door on the bottom of your iMac, wrap the bare wire around the screw and then tighten the screw; when connected to the grounded mat, that should give you a good static protection.

    It sounds like a line-conditioner is called for; a poorly regulated sine-wave, the 'CPS' or cycles-per-second of AC power, is disastrous to electronics and electric motors. I would trust APC, and don't skimp; look for a "pure sine-wave" output—low-end units often have "stepped sine-wave" outputs, which don't fully solve the problem.
     
  9. Kanunu thread starter macrumors 6502

    Joined:
    Apr 18, 2009
    Location:
    Hawaii
    #9
    Partial fix effected

    I found that all the mats on Amazon will not ship to Vietnam. Not sure why but it may because there are kind of steep duties on electronic equipment here. Sadly I was about a week too late to have it shipped to the Hawaii and have a friend bring it over. I will ask the Apple techs if they know where I can get one.

    I found some solid 20 gauge solid coated wire (maybe stainless) and went a step beyond Skinny*k's suggestion and actually went from the memory door screw, out the door to the balcony, down to the water meter, and did a bunch of wraps around a valve that had dog ears to get some purchase on. Fortunately, I had brought a small connector kit with me so the indoor end has an eye connector and looks somewhat presentable. Of course no resistor and straight to the ground and I need to look for a proper clamp.

    Net result is that I have not felt any shock since so I suspect that cyclotron451's idea of "capacitive coupling/leakage" was probably right. My connection is before the meter which I though better as I know some meters can isolate because they have plastic in the unions. Hopefully, I will not be feeling a tingle in the shower tonight. :)

    I still want to get the mat and will be asking around but it may have to wait until my next "care package" opportunity. I am definitely checking out the local APC reseller next week. Thanks for pointing out the distinction on "pure sine wave". Hopefully the specs will be on the box.

    By combining your thoughts I got the job done. That's how these forums are supposed to work. Thanks to both of you.
     

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