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Question on ESD

Discussion in 'A+' started by loretta, Jan 24, 2007.

  1. loretta

    loretta New Member

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    Hi all,

    I'm going through the A+ course and have got an old computer I can work on. I've managed to purchase an anti-static wrist strap but when I asked the tech guy about a mat he told me that I didn't really need one and that as long as I had the strap on and was plugged in at the mains so I was grounded it would be ok.

    Does anybody have any advice on this as I really don't fancy playing about with something that is plugged in to electricity!!

    Thanks in advance,
    Loretta
     
    Certifications: HND Computing
    WIP: BSc Honours Degree
  2. Bluerinse
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    Bluerinse Exabyte Poster

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    Then unplug it, as long as you have your wrist strap on and the clip is connected to the case of the PC it will be fine. You do not need to plug the computer in to effectively elliminate the static problem. You just need to make sure that you and the computer have the same tribo-electric charge. The strap alone will do this - The tech that told you otherwise was mis-informed.

    As for the mat, well that is optional I would say, I don't use one.

    What we are talking about here has little or nothing to do with the way conventional electronic circuits work and static is confusing for many IT people that don't have a background in electronics.
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  3. BosonMichael
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    BosonMichael Yottabyte Poster

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    Yes, according to books and such, you're supposed to take all sorts of anti-static protection to prevent damage to computer components. But to be honest, I never use them, and after working on thousands of computers, I have yet to see one damaged by ESD. I've built all my home PCs, and the worst that's happened thus far is a failure in two cooling fans, which have nothing to do with ESD.

    Just take reasonable precautions... touch the side of the case or a metal object to release built-up static charge, don't work on a carpeted surface, don't drag your feet on carpet while working on a computer, minimize touching any traces or leads... and obviously, unplug everything that is powered (power cord, monitor cable, network cable, phone line for those of you still living in the '90s).
     
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  4. Bluerinse
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    Bluerinse Exabyte Poster

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    Yes it's true that you don't even need to wear the strap, many people can't be bothered and take other precautions as BBM has stated.

    The damage that could be caused is real enough, it is not a myth but static charge depends a lot on the environment you are working in i.e. humidity, carpeting, clothing etc. So, it's probably best to advise new people to use the strap and minimise the risk.
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  5. Mitzs
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    Mitzs Ducktape Goddess

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    i work on them with it plugged in, wearing a wrist strap, and still making some kind of contact with the metal casing. I have had some tell me that this is too much, but then i think those that do nothing are not being a responable tech either. I've never been shocked with them plugged in. Not saying it can't happen, just saying that it has never happen to me.
     
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  6. Bluerinse
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    Bluerinse Exabyte Poster

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    As long as you do not delve inside the PSU (power supply unit cage) you should be fine. In fact it is safer to unplug the computer as with some MOBOs there are still voltages applied to the motherboard - you can still see LEDs lit on some boards when they are shut down. Clearly the voltages outside the PSU are not sufficiently high to give you a jolt but they are capable of damaging tiny components on the board if you accidentally shorted something out.
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  7. Mitzs
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    Mitzs Ducktape Goddess

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    i'll have to be honest blue, i've not acome across any like this yet. But I only do family and friends now and all theirs are older computers. As a matter of fact my mom and I are the only ones with xp, and I have a sister inlaw who is still on windows 95:eek:
     
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  8. Bluerinse
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    Bluerinse Exabyte Poster

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    Well if you think about it Mitzs there must be voltages still on the motherboard when the PC is shut down.

    For example, the on/off button is connected to the motherboard, not directly to the PSU. So, how could the PSU know that that button had been pressed if there was no voltage present - answer = it wouldn't know. Also USB I believe on some MOBO's the one I am using at the moment for example stays powered when this machine is shut down.

    Hence I unplug the PSU from the mains and wait a while for everything to die down before I jump in and start working on the thing.
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  9. tripwire45
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    tripwire45 Zettabyte Poster

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    Man, this thread went the distance. Books have to tell you to take all kinds of precautions because if they tell you it doesn't matter and you fry some obscure circuit path on your motherboard anyway, it's possible that you might sue them.

    What everyone has said thus far is true. When I'm working on other people's computers, I use a wrist strap just to be on the safe side. When I'm working on my own computers, I just grab the metal frame of the case before getting to work. Never had any problems so far.
     
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  10. Bluerinse
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    Bluerinse Exabyte Poster

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    You are safe here James, we don't sue other people for our own ineptitude, we couldn't be bothered and don't have the readies - that is a rich boy Boise thing :p
     
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  11. tripwire45
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    tripwire45 Zettabyte Poster

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    I meant in general, not here in River City, Pete. :tongue
     
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  12. BosonMichael
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    BosonMichael Yottabyte Poster

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    Yep - sorry if my post made it sound like I don't believe ESD to be a problem... because it certainly is real and can indeed damage components. Those of us who have been opening up computers for years have sorta figured out (sometimes the hard way!) how and where to handle components to minimize risk. But I definitely agree that it's best to advise new people to use the strap.

    "Use the strap... or you'll get the STRAP!" :cracking
     
    Certifications: CISSP, MCSE+I, MCSE: Security, MCSE: Messaging, MCDST, MCDBA, MCTS, OCP, CCNP, CCDP, CCNA Security, CCNA Voice, CNE, SCSA, Security+, Linux+, Server+, Network+, A+
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  13. BosonMichael
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    BosonMichael Yottabyte Poster

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    I've actually been mildly shocked inside the computer case by having the monitor plugged in! :ohmy Brushed up against the side of a video card and got a little ZOT! The components survived, but ever since then, I've made sure the monitor cable is unplugged before working inside a case.
     
    Certifications: CISSP, MCSE+I, MCSE: Security, MCSE: Messaging, MCDST, MCDBA, MCTS, OCP, CCNP, CCDP, CCNA Security, CCNA Voice, CNE, SCSA, Security+, Linux+, Server+, Network+, A+
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  14. BosonMichael
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    BosonMichael Yottabyte Poster

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    Most motherboards will even have a green LED on the board that indicates the presence of power (and sometimes, the Wake On LAN feature being active).
     
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  15. Bluerinse
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    Bluerinse Exabyte Poster

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    Hehe I wish I had been there to see that :twisted:
     
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  16. loretta

    loretta New Member

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    Thanks guys,

    I can now work in peace.

    Cheers,
    Loretta :biggrin
     
    Certifications: HND Computing
    WIP: BSc Honours Degree
  17. Boycie
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    Boycie Senior Beer Tester

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    When I went on a classroom course for PC building, the instructor gave us a lead to keep for our toolkit's.

    It was a mains lead intended for working on a PC that only had the earth pin in the plug. Because the earth pin is the longest (UK) it will go in the socket, allow your ESD strap to earth and not put any power in to the PSU.
     
    Certifications: MCSA 2003, MCDST, A+, N+, CTT+, MCT
  18. Bluerinse
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    Bluerinse Exabyte Poster

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    Again, I would argue that this is not necessary :wink:
     
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  19. C_Eagle

    C_Eagle Byte Poster

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    Wow this thread is getting bloated!

    I'm well known at my place for my attitude to ESD. All the engineers are provided with mats and wrist straps and the mains plug earth.

    I've been on a ESD course many years ago and the danger is very real. Not in a sense that the memory will explode or the HDD will fail to work etc but viewed under a microscope the damage to the tiny (microns) tracks in memory and CPU's are viewable. Although they won't cause the memory (in some cases) to fail they can seriously degrade the performance of the component affected. (Never more so than in server applications)

    Some places I've worked had static mat type flooring (laptop company) across the repairs area and the laptop build rooms at a cost of thousands! Why would they bother if there wasn't a risk of failure?

    (Can't help thinking I've thrown fuel on the fire but that's my view)

    I work with Techs who laugh at the matts they all have and never use them. When you go to the users desk to upgrade there memory and they say "don't you use any special equipment" etc. Even though they aren't techs it's well known that static bags and matts are needed.

    A good engineer will always use some kind of ESD kit when taking apart any electrical device with volitile components. (Or at least seen to be taking precautions!)

    I'm just a stickler for this as I've seen the damage it can cause. Also it looks professional when you break out your mat etc. I suppose I just take pride in my work!

    * Another point to add is when your changing the components in your PC you should always have your mains unplugged. Holding the case will do nothing for the ESD as the earth point is no longer connected? **
     
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  20. Bluerinse
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    Bluerinse Exabyte Poster

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    Static has nothing to do with earth. that is a misconception :wink:
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)

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