TechSpot

Teen electrocuted while salvaging parts from a computer

By Shawn Knight
Oct 12, 2012
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  1. shamus087

    shamus087 TS Rookie Posts: 27

    Well this has been educational! I always take apart the PSU when I clean the computer, only one time have I heard that those capacitors store power even when switched off and disconnected from the wall, glad I took those words to heart when my buddy told me >.>....

    The PSU I noticed attracts allot of dirt, and then when the fan fails and you have to custom mod it to fit the new 120mm fan.

    This is crazy, didn't really realize I was playing with fire like I was. Definitely going to take allot more care when I clean it again...

    Like other users mentioned though, I always discharge the power before I take it apart, I switch the unit off then disconnect it from the wall then press the power button to make sure none is left over.
     
  2. Shocking...
     
  3. Boys and girls, is this really can happen? I mean zapped from capacitor could lead to death? from my experience I once accidentally bumped with the capacitor with the size of a gluestick (but shorter in height) when checking/stripping one of my lab device (of course it's unplugged), I bumped it when I want to reach the cover, then what I got is a small electrical burn on left side of my boobs
     
  4. treetops

    treetops TS Evangelist Posts: 1,724   +63

    Lol its not bad luck the kid was messing around in a power supply unit, which clearly warns people do not f with it, all over it. They really just needs one big sticker saying EVEN WITH POWER CORD UNPLUGGED FATAL CHARGES REMAIN. I wonder if he knew the risk.

    My first computer repair college related class in chapter one was like do not ever take apart a psu or monitor unless your a trained professional, your risking deathly electrocution.
     
  5. spydercanopus

    spydercanopus TS Guru Posts: 802   +87

    Probably a high-powered VIDEA GAME chip. Yall happy now?! Gamin' KILLS!
     
  6. Benny26

    Benny26 TechSpot Paladin Posts: 1,578   +47

    This is going to put the creeps into the next time I open up my PSU for cleaning. Even though I've done it probably more than a 100 times without a single shock I'll still have this on my mind for next time.

    There was more to this story I feel.
     
  7. wiyosaya

    wiyosaya TS Enthusiast Posts: 282   +34

    Doublers have not been needed on well-designed, modern power supplies for years. I'm sure you can check this out by reading the specs on any well-designed modern supply - which will not have an input voltage selection switch. Many modern switchers have an input voltage range of 100V-240V, and you don't need to select the input voltage with a switch. Just get the right line cord and plug it in to the local outlet. For example - http://www.antec.com/pdf/flyers/BP550PLUS_flyer.pdf For a buck converter, it really does not matter what the input voltage is as long as it is sufficiently high enough over the output voltage to overcome conversion inefficiencies.

    So, what you are saying is that the kid had not unplugged the supply?
     
  8. This is rather scary.

    I open my PSU every now and then to clean or to maintain it's fan.

    Best thing to do is to turn off power and leave the PSU unplugged for 24 hours before maintenance, especially anything with big capacitors.
     
  9. Per Hansson

    Per Hansson TS Server Guru Posts: 1,933   +126 Staff Member

    Wiyosaya: Uh yea if you had continued to read my post you might have come to the part where I talk about APFC
    I guess I could have made it clearer but with APFC there is no voltage doubler stage, only the APFC stage.
    But as for the charge in the capacitor this is actually even worse because it is an even higher voltage, which was my whole point to begin with
     
  10. cliffordcooley

    cliffordcooley TechSpot Paladin Posts: 6,406   +1,595

    Remember the 35mm camera's with flash? Them little bad boys put out a jolt as well.

    It never occurred to me how much voltage was needed to operate a camera flash, until I discharged the capacitors in one with my fingers. Talk about a wake up call, that was worse than being shocked by a wall outlet. I instantly formed a question of how a 3V DC device could shock worse than 120V AC wall outlet.

    How Camera Flashes Work
    200V :eek: 1000 - 4000 :eek::eek::eek:
    From a 3V camera??? WOW
     
  11. This REEKS of Urban Myth to me.
     
    pidjones and avoidz like this.
     
  12. PSUs should be replaced not repaired. They are so cheap these days, even excellent quality high wattage units are reasonably priced for the job they do. The closest I ever get to the inside of a PSU is with compressed air to blow dust particles out.

    Over recent years of fixing computers I have also had instances of a computer running normally at a client's house only to have the PSU "blow" back at the workshop due to excess dust arcing and blowing the PSU as soon as the power cord was attached. Since then I have dusted PSUs out with compressed air before attaching a power cord. Respect electricity.
     
  13. Well, maybe it is just sensationalism or maybe just bad luck?, I work as IT fixing computers and printers and in my 7+ years in the business I've been shocked by flybacks (CRT Monitors), I have shortcircuited capacitors of around 200V (the big ones), and maybe the worst was the flyback, it left me with headaches for 3 days, but didn't kill me, if this is true, the guy was either bare feet and/or wet and/or suffered of heart affections, only accurate info would tell us.
     
  14. andymac26

    andymac26 TS Rookie

    Or just short the cap out with an insulated screwdriver, been doing it for years in my industry. never damages anything.
     
  15. 9Nails

    9Nails TechSpot Paladin Posts: 994   +89

    My heart goes out to the father. I couldn't imagine the pain and loss of a child. The young man who lost his life working on a hobby that I've done thousands of times myself for business and personal use and never considered to be this dangerous. I hope that this is one of those very unusual set of circumstances and peculiar accidents which aren't common. But to lose a son, a young man starting his life, it is such a heart breaker.
     
  16. IT always makes me wonder of how ignorant people are! Most users comment that they press the power after having disconnected the power cord. So let me guess you think the capacitor just going to discharge? Let me see. A computer using maybe 5 volts and is run by a 120 volt power source. So you think that small electronics going to just discharge it real quick. A laptop runs 3 to 8 hours on battery. So your system being a little bigger like lets say a desk top computer uses much more power then that. Think again. Even if you press that button for 3 hours there is still a chance that you will have a kick in there. Your best bet is to use gloves. Also when working on power supplies don't ground yourself for that is a deadly mistake. Also think of this a capacitor is an independent circuit. It stores over flow not usage. If there is a circuit it steps down the current by taking the access off. So how do you think you going to discharge it by simply pressing the power button while it is not plug in genius.
     
  17. cliffordcooley

    cliffordcooley TechSpot Paladin Posts: 6,406   +1,595

    Firstly - A normal desktop does not have a battery to keep it running for hours (thats what a power cord is for).
    Secondly - They were referring to pressing the Power Button and the motherboard sending a power good signal to the PSU, therefore switching the power rails on and quickly discharging any stored power inside the PSU.
    What???
    In short, capacitors are used to level off peak AC voltages to regulate a flat DC output for usage. These capacitors are not a sideline component, they just as important as any other component in the system. One faulty power capacitor and you could have massive amounts of voltage ripple through out the entire electronic system. Notice I said power capacitors because capacitors do have other functions of filtering frequencies.

    Your comment disgust me after reading your first sentence. You should never speak of others ignorance, unless you know exactly what you are saying.
     
    ghasmanjr likes this.
  18. Prosercunus

    Prosercunus TS Enthusiast Posts: 122   +9

    I wondering what he was doing. You never try to save or take parts from a PSU. Don't even open them.

    Properly dispose of them when they go bad.
     
  19. I sugest that you don't comment if you have no clue of what you are talking about. Here is a quote for you.
    Capacitors are widely used in electronic circuits for blocking direct current while allowing alternating current to pass, in filter networks, for smoothing the output of power supplies, in the resonant circuitsthat tune radios to particular frequencies, in electric power transmission systems for stabilizing voltage and power flow, and for many other purposes.[
    So as you see it is exactly as I commented. You can see a capacitor as an independent of AC or alternating current. It stores direct current while letting AC pass through. So if there is no ac to pass through do you think a stupid thing like a capacitor going to grow brains and convert dc to ac just so in can discharge for you genius.
     
  20. cliffordcooley

    cliffordcooley TechSpot Paladin Posts: 6,406   +1,595

    Wrong, the capacitor charges creating a DC voltage which kills AC voltage. There is no pass through AC voltage. The property of having a DC PSU is to convert AC to DC. If you have an AC signal on the output of a DC power supply something is wrong. You should stop now before you embarrass yourself further. Ohhh, thats right you are hiding behind a guest account, no wonder you are saying things that don't make sense.
    Just to let you know you are implementing the definition of a filter capacitor as a power capacitor. The difference is one is in series with the circuit while the other is in parallel with the circuit. A power capacitor is placed in parallel with the circuit. A capacitor used as a filter placed in series with the circuit will allow AC frequencies to pass and effectively blocking DC voltages. DO NOT GET THE TWO MIXED UP!!!
    Lets get one thing straight, by that statement you seem to think that AC is a requirement for discharge. AC voltage can never be stored, therefor never discharged. A discharge will always be the release of a stored DC voltage. AC voltage can jump but that is not the same as discharging.
    Do us all a favor and be quiet so we can get back on topic. Paying our respects to the teen that died from a discharge that you obviously don't understand.
    Ohh and thanks for the links but I don't need a refresher course in basic electronics.
     
  21. cliffordcooley

    cliffordcooley TechSpot Paladin Posts: 6,406   +1,595

    The voltages don't get stepped down, they are switched off, disconnected from the motherboard. Step-down is a term used when voltage goes through a step-down transformer. You can't even get the most basic terminology correct, so why would I listen to you about electronics. Stop talking **** and confusing people. If you didn't spread trash I wouldn't have anything to try and correct. And OMG for the first time in my 40 years of life someone is calling me a bully.

    I've derailed this thread long enough, good luck spreading your misconceptions and misguided truths around the Internet. I have had my fill of this conversation and have nothing further to say to you. Its sad really that you would pick this thread of all threads to play your games in.
     
  22. wartech0

    wartech0 TS Rookie

    PSU are nothing to mess with. The capacitors do carry enough current to kill if you grab a live terminal and ground with both hands. I have had a cap shock me out of a disposable camera before, it hurt pretty bad and luckily I was holding it in one hand. 60mA is enough to kill that isn't really a whole lot either.
     
  23. That doesn't work. Where does the electricity go if it's not connected to a ground? It stays inside the power supply.
    Pressing the power button after it's turned off would only drain any electricity in the motherboard or peripherals back into the PSU. Which is good, unless you plan on opening it...
     
  24. veLa

    veLa TS Booster Posts: 533   +88

    It's very simple. Never open a power supply.
     
    avoidz likes this.


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