Is it safe to open an unplugged PC?

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Beaver
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Is it safe to open an unplugged PC?

Postby Beaver » Fri Sep 24, 2010 2:48 pm

Is it safe to open an unplugged desktop or laptop to replace parts such as memory and PC cards? Some websites I have read said this can be dangerous because a person can get a serious or lethal shock if they touch the power supply. Other websites I read said as long as the computer is unplugged it is safe to open because you can only get a minor shock or no shock at all if you touch the power supply. Which is correct? Here is some discussion:

http://answers.yahoo.com/question/index ... 744AAtKAMO

http://answers.yahoo.com/question/index ... 833AALF1eK

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Re: Is it safe to open an unplugged PC?

Postby jman111 » Fri Sep 24, 2010 2:59 pm

Well, as I am essentially technically illiterate and I have managed to place/replace memory cards in several computers, I think you'll be alright.
If you don't mess with the power supply, I think the risk is minimal. The risk is in discharging the capacitor(s). I have heard of people being killed by messing with the guts of an unplugged microwave oven, but I think they probably have much larger capacitors.
So, to paraphrase, I don't know...

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Re: Is it safe to open an unplugged PC?

Postby green union terrace chair » Fri Sep 24, 2010 3:30 pm

Never OPEN the power supply ... there are capacitors in there that can mess you up. But otherwise, if it's unplugged, you can do your thing with RAM, HDDs, etc.

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Re: Is it safe to open an unplugged PC?

Postby TAsunder » Fri Sep 24, 2010 4:29 pm

It's better if you ground yourself. You can get a wrist strap that you attach to the case to accomplish this I believe. There is some risk of static shock damaging the computer parts (though minimal risk of damaging yourself). Definitely don't touch any unshielded power source.

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Re: Is it safe to open an unplugged PC?

Postby ilikebeans » Fri Sep 24, 2010 7:29 pm

Yes, it's basically safe, since the power supply is fully encased and its connectors are recessed to shield from accidental contact.

The bigger concern, as noted, is accidental static electricity discharge from you to whatever it is you're touching. You can easily destroy components this way.

My procedure:

- Shut everything down. Unplug the computer. Open the case.
- Before you touch anything, and at regular intervals, touch bare skin to the metal chassis/case.
- Be absolutely sure you do this upon returning if you leave the computer and walk anywhere, especially on carpeting.
- Don't touch any metal parts on internal components if at all possible.

Also, don't put too much pressure on the motherboard when pushing in cards, etc. You can flex and crack connections and have very random and infuriating computer malfunctions.

If you're careful, you shouldn't have any problems. Good luck!

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Re: Is it safe to open an unplugged PC?

Postby Beaver » Sat Sep 25, 2010 10:09 am

Thanks for the tips.

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Re: Is it safe to open an unplugged PC?

Postby Petro » Mon Sep 27, 2010 7:18 am

ilikebeans wrote:- Shut everything down. Unplug the computer. Open the case.
- Before you touch anything, and at regular intervals, touch bare skin to the metal chassis/case.


Unplugging the computer severs the link between it's chassis and ground. Touching the chassis as a ground is ineffective at that point.

If the PSU has it's own power switch, set this to it's off position.

You'll sometimes find motherboards with small LEDs on them, or NICS that stay powered on for Wake-On-LAN - these generally only have 5V at some piddily amperage running through them. Even though they'll stay illuminated with the PSU plugged in, it's safe to work on the machine.

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Re: Is it safe to open an unplugged PC?

Postby Athena » Mon Sep 27, 2010 10:08 am

I've even changed out the power supply and lived to tell the tale. See if you can find the instruction manual for your computer (they're usually online at the company's website) and it should tell you anything extra you need to do and things you shouldn't mess with. I'd recommend not working on carpet if you can. It's really helpful to put the computer up on a kitchen table so you can see what you're doing. Make sure everything in unplugged before you open the case. Either the card you bought or the company website should have clear instructions and read through them before you start.

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Re: Is it safe to open an unplugged PC?

Postby ilikebeans » Mon Sep 27, 2010 12:48 pm

Petro wrote:Unplugging the computer severs the link between it's chassis and ground. Touching the chassis as a ground is ineffective at that point.

If the PSU has it's own power switch, set this to it's off position.

You'll sometimes find motherboards with small LEDs on them, or NICS that stay powered on for Wake-On-LAN - these generally only have 5V at some piddily amperage running through them. Even though they'll stay illuminated with the PSU plugged in, it's safe to work on the machine.

[geek]
My understanding was that, even with the cord disconnected and the machine isolated from ground, it's still a good idea to touch the chassis to bring your body and the computer to the same voltage potential, thus eliminating any static discharge from one to the other. Or is the danger then with handling a new component right out of the packaging?

Is there really much danger if you just unplugged the computer before doing the touching/installation work? Wouldn't the chassis, having just been at ground, still absorb any charge from your body, making the chance of problems almost nil?
[/geek]

But yes, I'd agree with you that if the power supply unit has its own power switch (most do), turn this off and leave the cord in to keep the chassis grounded. You still need to touch the chassis to bring yourself to ground as well before handling any components.

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Re: Is it safe to open an unplugged PC?

Postby Kenneth Burns » Mon Sep 27, 2010 1:01 pm

Desktop PCs are designed to be mucked around in. So unplug the computer, touch the chassis, and then start unscrewing screws and having fun. Consider backing up your hard drive before you start making big changes.

Typically, much less mucking around is possible with laptops. There may be a panel or two or three that you can remove to upgrade memory, swap out a hard drive, etc.

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Re: Is it safe to open an unplugged PC?

Postby rabble » Mon Sep 27, 2010 1:39 pm

ilikebeans wrote:[geek]
My understanding was that, even with the cord disconnected and the machine isolated from ground, it's still a good idea to touch the chassis to bring your body and the computer to the same voltage potential, thus eliminating any static discharge from one to the other. Or is the danger then with handling a new component right out of the packaging?

Is there really much danger if you just unplugged the computer before doing the touching/installation work? Wouldn't the chassis, having just been at ground, still absorb any charge from your body, making the chance of problems almost nil?
[/geek]

The whole thing about grounding and static is that it takes a very small static charge to kill some components. Small enough that we would never feel or notice it. Even though you grounded yourself by touching the chassis or any other piece of metal connected to ground somehow, you might be building up another charge with your shoes or your clothes, just waiting to silently kill your cpu without even making you flinch. Bwahahaha.

That's the standard line. In my case, in the dozen or so pc's I've built, modified or repaired over the last few years, sometimes under the influence, I have never bricked a component due to static discharge.

I had to put some real effort into it.


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