How are you supposed to repair while avoiding electrostatic discharge?

[sltech]

I've looked at various web pages and forums and there seem to be a lot of opinions on how you are supposed to make repairs to a computer while avoiding damage from static electricity.

First of all, there seems to be a difference between a desktop computer and a laptop computer. For a desktop computer, you could just wear an anti-static wrist band and then attach it to the metal chassis. But apparently most laptops don't have a metal chassis. So what would you attach the anti-static wrist band to if you are working on a laptop?

Second of all, some people say that you should leave the computer plugged into the outlet, that way it remains grounded and any static electricity that has accumulated on your body can dissipate by going to the ground. But I have seen other people say that you should unplug the computer to eliminate any chance of electrocution. So should you unplug the computer or leave it plugged in? Is it also necessary to turn off the power supply (I guess for a laptop that would mean removing the battery)?

Third, some people say that grounding the computer isn't necessary at all. They say the only thing necessary is for you to touch the computer so that the charge potential between you and the computer is equalized. Once equalized, there won't be any static discharges as you touch the computer. So what if you have a RAM module (or some other component) sitting next to the computer and you want to install it in the computer? You touch the computer and equalize the charge potential between you and the computer... but then wouldn't there be a static discharge when you pick up the RAM module, since it is at a different charge potential than you and the computer?

 

[dave_the_nerd]

1) Most of the anti-static straps I've used plugged directly into the wall, not into the computer. (They just had a plug with a single ground ping, rather that the three prongs, since that would kill you.) If you are using a strap which is attached to the computer and not the wall, you would need to have the computer plugged in, so you're actually grounded and not just tied to a computer.

2) If you do not have an anti-static strap, you can discharge by touching a still-plugged-in power supply or case, which are grounded. Leaving a computer plugged in while you're working on it would provide an easy way to keep/stay grounded. (Just touch the PSU every now and then.) This is riskier though, since you're not 100% grounded. But this is how I usually work.

2a) As long as you're not doing something stupid like opening up the power supply, there's no voltages you'd be exposed to - even with the computer running - which would be harmful. Just lots of things you could break. Accidentally turning a computer on while you're in the middle of installing RAM is... potentially bad.

3) This is wrong. Do not do this.

 

[DigDog]

you attach the wristband to anything grounded, so a radiator or a water faucet would be ok.

also, you need to be in a problem area (really bad, old building with poor grounding, extreme synthetic carpeting and reflux air circulation) to have enough static to damage components.

 

[CoPhotoGuy]

Or you just don't bother with a strap. I've never used one and done tons of computer repair. Never any issues. Just touch the case to dissipate any charge and you're fine after that unless you go away from where you are working.

 

[sltech]

1) Most of the anti-static straps I've used plugged directly into the wall, not into the computer. (They just had a plug with a single ground ping, rather that the three prongs, since that would kill you.)

I know what you are talking about, but I can't find that plug anywhere online. All of the anti-static wrist straps I've seen have the alligator clip.

If you are using a strap which is attached to the computer and not the wall, you would need to have the computer plugged in, so you're actually grounded and not just tied to a computer.

2) If you do not have an anti-static strap, you can discharge by touching a still-plugged-in power supply or case, which are grounded. Leaving a computer plugged in while you're working on it would provide an easy way to keep/stay grounded. (Just touch the PSU every now and then.) This is riskier though, since you're not 100% grounded. But this is how I usually work.

Do you have to turn the PSU power switch off?

2a) As long as you're not doing something stupid like opening up the power supply, there's no voltages you'd be exposed to - even with the computer running - which would be harmful.

I was wondering if I was working on a laptop, could I attach the anti-static wristband to the chassis of my desktop computer, while the desktop computer is running. That wouldn't be a problem then?

also, you need to be in a problem area (really bad, old building with poor grounding, extreme synthetic carpeting and reflux air circulation) to have enough static to damage components.

In the winter I sometimes feel static shocks walking around the house. Also, I've heard that you don't need to feel a shock in order to damage electronic components.

Or you just don't bother with a strap. I've never used one and done tons of computer repair. Never any issues. Just touch the case to dissipate any charge and you're fine after that unless you go away from where you are working.

What if you are working on a laptop - what would you touch? I've heard most laptops don't have anything metal inside that you can touch.

 

[bryanl]

Second of all, some people say that you should leave the computer plugged into the outlet, that way it remains grounded and any static electricity that has accumulated on your body can dissipate by going to the ground. But I have seen other people say that you should unplug the computer to eliminate any chance of electrocution. So should you unplug the computer or leave it plugged in?

Unplugged. The people who say otherwise are ignorant and don't understand the purpose of the megaohm resistor in series with the grounding cable of anti-static straps. They may also not know the difference between earth ground and chassis ground and why the latter matters more in regards to ESD.

See what the semiconductor industry recommends for ESD protection since they know more about it than anybody else. Examples:

http://www.minicircuits.com/app/AN40-005.pdf
http://cds.linear.com/docs/en/quality/esdprotection.pdf

It's desirable to be constantly connected to chassis ground since static builds up very quickly, and merely touching the case periodically isn't nearly adequate. Using an anti-static work surface is better and more convenient than relying solely on an anti-static wrist strap.

but I can't find that plug anywhere online. All of the anti-static wrist straps I've seen have the alligator clip.

They're common:

http://solutions.3m.com/wps/portal/...le-Metal-AMWS121M?N=7575749+3294757973&rt=rud

But they're probably not what you need. Plug-in wrist straps are for use in labs and assembly lines where the anti-static work areas have grounding receptacles for them.

Raise the humidity level of your home.

 

[CoPhotoGuy]

What if you are working on a laptop - what would you touch? I've heard most laptops don't have anything metal inside that you can touch.

Then I would just touch another case or whatever. I've probably fixed hundreds of laptops and build several hundred computer systems and never wore an ESD strap. We had a rubber mat on the floor so we weren't walking on carpet and some padding down on the workbench but that's it. Never any issues.

 

[piasabird]

Only an idiot leaves his computer plugged in and then opens it to work on the motherboard or a drive or something like that. Even when you power down a computer, the motherboard still has power running to it. Otherwise, how could your power supply know when to turn on when you press the power button or the mouse or the keyboard? Only way to make sure all the power circuits are off is to unplug the computer.

Better safe than sorry.

I suppose you could just turn the power off on the power strip you are using and also on the switch on the back of the power supply if it has one. However, that one time you forget you could zap something.

I have on an occasion removed a side panel to see if all the fans keep working. It still is not a good Idea to try to move wires around while the computer is running or unplug a DVD drive or something like that.

 

[CoPhotoGuy]

Only an idiot leaves his computer plugged in and then opens it to work on the motherboard or a drive or something like that. Even when you power down a computer, the motherboard still has power running to it. Otherwise, how could your power supply know when to turn on when you press the power button or the mouse or the keyboard? Only way to make sure all the power circuits are off is to unplug the computer.

Better safe than sorry.

I suppose you could just turn the power off on the power strip you are using and also on the switch on the back of the power supply if it has one. However, that one time you forget you could zap something.

I have on an occasion removed a side panel to see if all the fans keep working. It still is not a good Idea to try to move wires around while the computer is running or unplug a DVD drive or something like that.

That's a pretty sweeping statement. You can do some work, just depends on what and how careful you are. Last night I added an SSD in my system with it powered off but plugged in. Everything still works. Amazing. Now, am I going to go removing or adding PCIe cards, RAM or fiddling with the motherboard? No.

 

[mfenn]

Unplugged. The people who say otherwise are ignorant and don't understand the purpose of the megaohm resistor in series with the grounding cable of anti-static straps. They may also not know the difference between earth ground and chassis ground and why the latter matters more in regards to ESD.

Absolutely 100% agree.

You're trying to remove the difference in potential between your body and the components. Whether or not you're at true earth doesn't matter, as long as you're at the same potential as the things you're working on.

Plugging in the PC doesn't give you any benefit and just increases the risk of accidental damage to yourself (or more likely) your components.