[Plutox]

All advise using an anti static wrist strap when delving inside the computer works but there is never info on how to use it.
My query is:- Where does one attach the free end? To the computer case itself or to a water or central heating radiator pipe or to the earth pin of my house current plug or what?
Advice gratefully received.

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With hindsight.. wrong advice: edited to remove..

Fred..

[Fred Flintstone]

With hindsight.. wrong advice: edited to remove..

Fred..

[happyrock]

Make sure the power cord remains plugged in so the case itself is earthed / grounded.

the problem with this is...if the computer is plugged into the wall there is still power to the motherboard


While working with a electrostatic sensitive hardware you could place your wrist in the strap and plug the other end into an antistatic mat the device is laying on or into an antistatic workbench.

[hfcg]

Hello,
NEVER work inside of a computer while it is plugged in!
I rest one forearm on the case while I am working inside of it.
This makes me feel like I am grounded twice, one by the antistatic wrist strap, and by my physical contact with the case.
There are cordless wrist straps, like this Example, if you do not like the cord getting in your way.
Just a note, static electricity can carry several thousand Volts. Use some anti-static protection when working on sensitive electronics.

[SOORENA]

I was taught to just touch the power supply to get rid of any static and then touch other components, besides if you are opening your case chances are you've already grounded yourself by touching the chassis. And I too advise you not to touch computer parts while they are on, not unless you are professional.

Soorena

Edited by SOORENA, 02 March 2008 - 08:41 AM.

[Fred Flintstone]

Hi,
I bow to your hardware experience and have edited out the info in my original post.
Couple of points though:

While working with a electrostatic sensitive hardware you could place your wrist in the strap and plug the other end into an antistatic mat the device is laying on or into an antistatic workbench.

This is of course the correct way, but most people don't usually have access to this equipment when needed?

I rest one forearm on the case while I am working inside of it.

As do I.. never had any problems with this method when carrying out tasks like changing memory sticks / various cards etc.. but as far as the strap goes, unless you have it connected as above (to a mat or something) it would be of little use?
(No use just connecting it to the case if the power cord is not in) ??

Just a quick question since we are on the subject of voltages etc as hardware is not my best suit:
If the PC is powered down (though the cord is still in place) surely there would be no voltages going to the motherboard as suggested above??
Else, why the need for the CMOS battery to power the settings storage on the MB??

Thanks
Fred..

[hfcg]

When you "power down" a computer there is still electricity going to the motherboard.
Even if the computer is shut down hard there is risk of shorting out the motherboard, or other components. Plus electicution. (1 volt pushing 1 Amp, creating 1 Watt, can kill you.)
Why take the risk when it only takes 5 seconds to unplug the machine.
Yes, the capacitors do store a charge, so wait a moment before digging in.
The nature of static electricity is that it is high in voltage with little amperage. This allows it to be discharged easily.
Have you ever shocked youself, or some one else, by touching some thing metal (or some one)?
Here and here are some articles about static electricity.

[SOORENA]

Or you can always press the power button on the PSU to off or 0 which will get rid of any power in the motherboard. That should be the first thing you do before yanking out the cord.

Soorena

[Fred Flintstone]

Hi SOORENA,

Or you can always press the power button on the PSU to off or 0 which will get rid of any power in the motherboard That should be the first thing you do before yanking out the cord.

Soorena

Which brings me back to the point... why "yank the cord" if there's no power in the motherboard??
Switch the PSU off and the MB is effectively dead, leave the cord in place and the case is still earthed??

Thus, connect the strap to the case and you get the anti-static protection you need!??

[SOORENA]

Precisely although the PSU is off and the mobo has no power touching the PSU will send any static through the chassis of the PSU to the cord and then to god knows where.

Soorena

Edited by SOORENA, 02 March 2008 - 07:13 PM.

[hfcg]

The motherboard will still have power.
Most motherboards will put an ATX power supply in the standby mode if the front panel Power-on switch pushed and held in for 4 seconds. It is a long four seconds for most motherboards power supply combinations. Count one thousand, two thousand,... five thousand... The CMOS Setup for many motherboards has a setting that can change the 4 second "Power-off" (standby) to "Instant off." Many recent ATX power supplies have a separate power switch on the power supply that will turn-off the supply (including +5VSB) as surely as a light switch will turn-off the lights in a room. That switch is handy when installing expansion boards in a computer, etc., but should not be used for a normal power-down. To avoid damage, pull the power cord to kill all power (+5VSB) when installing expansion boards, drives, etc. if there is no such switch.

[james_8970]

Unplugging the computer restricts user error, which is why I like to ensure that the PSU is disconnected from the wall at all times.
James

Edited by james_8970, 02 March 2008 - 07:32 PM.

[Plutox]

Thanks for all your responses. There's a lot of opinion about this subject it seems. The company man from whom I bought my RAM to install said that he never uses any anti static devices - just slots it in!

Switching off the unit but leaving in plugged into the wall socket but also switched off there and connecting the strap to the chassis seems the most logical.

I've just called a local computer repair shop and he confirmed that procedure. Should have done that before but this thread may help others.
.

[jeffk813]

The theory of the anti-static strap is that if you and the computer chassis are at different levels of electrical charge, or electrical potential, there is the possibility of generating static electricity. This charge flow can be damaging to CMOS type components even if there is no spark. As little as 2000v can damage a CMOS IC, whereas it takes about 20,000v to generate a spark (yes, even the little ones at the tips of your fingers).

Connecting a static strap to your wrist, and the other end to the chassis will provide a connected path between you and the chassis for the electrical charges to flow, and therefore equalize. This will help prevent damage to components. It's irrelevant if the computer is plugged in or not as far as this is concerned, but it's indeed hazardous to have the PS plugged in. Calling them "grounding straps" is really a confusing thing. You don't so much "ground" yourself as much as you equalize the electrical potential between you and the computer.

Just touching the chassis with your bare skin while working on the computer will indeed do the same thing as the strap, but there's always the possibility that you'll forget. Also, as you move your feet on the carpet, you'll be generating charge, so your potential changes constantly. Just touching the chassis briefly and then grabbing a board is not a guarantee of safety. You must be in contact the entire time.

Another little trick we used at my old shop was to put a few drops of liquid fabric softener in a spray bottle of water and spritz down the carpeting around the shop benches every morning. This reduced the tendency of the carpet to produce static charge and made the room smell spring fresh too!

[Plutox]

Good post Jeff - that just about wraps it up.