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Windows 7: Teen electrocuted while working on unplugged computer


10 Oct 2012   #21

Windows 8.1 Pro
 
 

Quote   Quote: Originally Posted by 0pTicaL View Post
Quote   Quote: Originally Posted by boohbah View Post
reading through the comments this one was the only decent comment, poor kids family will be devastated.

Quote:
The lack of respect here for the death of a young person is saddening. He was a geek like the rest of us and his death was accidental. He could've grown to be the next Steve Jobs and his family is likely crushed. RIP. Posted by kurokitsune
His death is tragic, yes, but he was not a geek. A real geek would have known better. A real geek would know how to discharge all remaining power before working on a PSU. Just like people who clean windows on skyscrapers know they should be wearing a safety harness at all times.

Apparently in the tech field, too often you see people who think they know it all, and sadly this is one of the more extreme results.
I have to somewhat disagree as all of us DON'T necessarily use safe practices while working around electronics. We should, but most of us just take for granted it won't happen since I've done this a thousand times. And when stories like this pop up we realize how lucky we were, and hopefully get back to the basics of safety.

That said, as a youngster I got a good jolt messing with the high voltage fly back wire on a picture tube. Taught me a good lesson about that wire! Thank god I'm still here. Recently while performing some repairs on my 40 inch CRT tubed TV, I made darn sure I discharged that cap.

I also have to admit I’ve opened up a few power supplies and poked around myself

Anyway, it's good that Brink posted this as a reminder that we can't take electricity for granted... even in a computer. Hopefully some learn from this tragedy.

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10 Oct 2012   #22

Win 7 Ultimate (64-bit), Win 8.1.1 (64-bit)
 
 

Quote   Quote: Originally Posted by bdstx4 View Post
All it takes is 28Vdc and 50milliamps to stop your heart. Be careful people.
It only takes a small amount of current to pass thru your heart and interrupt the rhythm of your heartbeat. How much voltage is required to do that varies greatly due to many factors such as how close to the heart the contact point is, the moisture content of your skin, humidity, etc...
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10 Oct 2012   #23
Microsoft MVP

 

Does holding the power button for x seconds actually discharge the residual power in the capacitors or is that for something else?

Yesterday my nephew was swapping in a new PSU for my Dad's desktop which was left only with a blinking green LED on back of PSU. He reported that when he plugged up the new PSU it had a solid green. Does this LED show residual power, or just power on?
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10 Oct 2012   #24

Dual-boot: Windows 7 HP 32-bit SP1 & Windows XP Pro 32-bit SP2.
 
 

I really do feel sorry for those parents. Whatever he thought he was doing, he obviously didn't heed any warnings etc at all.
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10 Oct 2012   #25

Operating System : Windows 7 Home Premium Edition 6.01.7600 SP1 (x64)
 
 

so sad 16 years is nothing thanks for sharing this brink
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10 Oct 2012   #26

Operating System : Windows 7 Home Premium Edition 6.01.7600 SP1 (x64)
 
 

Quote   Quote: Originally Posted by gregrocker View Post
Does holding the power button for x seconds actually discharge the residual power in the capacitors or is that for something else?

Yesterday my nephew was swapping in a new PSU for my Dad's desktop which was left only with a blinking green LED on back of PSU. He reported that when he plugged up the new PSU it had a solid green. Does this LED show residual power, or just power on?
even when you think you have discharged the psu by pressing the power button down the capacitors still hold power same as a old style tv etc, i used to work on coolers many years ago and when we unplugged them to refurbish them we had to discharge the capacitor connected to the refrigeration unit using a heavy insulated tool that shortened it out.
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10 Oct 2012   #27
Microsoft MVP

 

This thread may literally be a lifesaver because I was soon going to take apart my Uncle's big screen plasma TV to see if I can spot capacitor damage after it (possibly) fried during power surge. I have a video showing how to do this but with nothing said about discharging residual current. Will a voltage tester suffice held on the leads of a capacitor which appears to need replacement?
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10 Oct 2012   #28

Windows 8.1 Pro RTM x64
 
 

Discharging a capacitor involves placing a load across its terminals so that the stored energy is dissipated safely. The load is typically a wirewound power resistor, although a mains light bulb can also be used. If a voltmeter is connected in parallel, you can also see the residual voltage reduce until it is close to zero (although it will probably never actually be exactly zero).

A word of warning: Never touch the terminals of the capacitor directly, and also be aware that any residual power left in any other capacitors could potentially recharge the capacitor you have discharged. Ideally, you need to isolate one of the capacitor terminals from the rest of the circuitry to prevent this from happening. Above all, never try to discharge a capacitor by merely shorting its terminals, as this can lead to the capacitor rapidly overheating, with the resultant possibility of it exploding or even catching fire (or both).
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10 Oct 2012   #29

Windows 8.1 Pro
 
 

Quote   Quote: Originally Posted by gregrocker View Post
Does holding the power button for x seconds actually discharge the residual power in the capacitors or is that for something else?

Yesterday my nephew was swapping in a new PSU for my Dad's desktop which was left only with a blinking green LED on back of PSU. He reported that when he plugged up the new PSU it had a solid green. Does this LED show residual power, or just power on?
Yes. And some capacitors can hold charges for days, maybe even weeks! Also some can hold large amounts of current. But, I would think a typical power supply's capacitor would only hard a charge for a couple of hours.

- HowStuffWorks "How Capacitors Work"
- How to Discharge a Capacitor: 5 steps - wikiHow
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10 Oct 2012   #30

Operating System : Windows 7 Home Premium Edition 6.01.7600 SP1 (x64)
 
 

Quote   Quote: Originally Posted by gregrocker View Post
This thread may literally be a lifesaver because I was soon going to take apart my Uncle's big screen plasma TV to see if I can spot capacitor damage after it (possibly) fried during power surge. I have a video showing how to do this but with nothing said about discharging residual current. Will a voltage tester suffice held on the leads of a capacitor which appears to need replacement?
thanks dwarf has answered with good advice for you gregrocker exactly what i would of told you for discharging a capacitor.
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 Teen electrocuted while working on unplugged computer




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