best way to ground myself before opening the case

[bilebalar]

hi,

i need to change the motherboard of a computer (1st time doing this). what is the best way to ground myself? there's carpet on the floor. i usually just touch the metal part of the power supply when i swap memory stick. there's no other metal object around i can use to ground myself. please advise me of the best way to ground myself before changing the motherboard.

thanks.

 

[edfair]

Although you will get all sorts of contrary advice I suggest that you continue to do what you are doing.
Just make sure the power is totally removed (from the wall connection) before you start. And you might want to rest an arm on the case as you are pulling the board. That will prevent any buildup of static potential between the board and you while you are doing the work.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[bcastner]

To emphasis a point by Ed Fair, you are not looking for a metal object ground per se. You want to be at zero potential between yourself and any object you are going to handle.

You might do the swap on a non-carpetted surface. As long as a part of your body is in touch with the case as you do the work you should be fine. Computer stores carry a wrist strap you can purchase inexpensively, but I have never worn one for the level of repair you are discussing.

 

[orypecos]

What you are wearing has a effect too. A synthetic wig or cloths can cause a lot of static electricity in addition to wool rugs. In addition, usually the dryer the climate, the more static electricity build up. I usually try to avoid touching any conductive parts of what I am changing and use a high impedance grounding strap. Be aware that most power supplies have capacitors that retain power even with power disconnected. On a television/monitor it is enough to kill you.
Extensive study by Bell Labs has shown that most of static electricity damage is not evident immediatly. Failure is usually later and sometimes intermittant.

 

[cbs604]

Make sure you have everything you need within reach - screwdriver, new MB, coffee etc... and don't move about while doing the change - this is where a huge charge can build up, particularly if the air humidity is low.

Ground yourself on the PS case by holding your hand flat on the surface for a few seconds before removing the old MB. Only handle the new MB by the edges.

As orypecos said, the PS filter caps can hold a charge after the power is removed, however, that will dissipate very quickly while the MB is still connected.



Cheers,
Brodie

 

[garebo]

I agree with the statements here, but i hear one thing that contradicts what i have heard from others. I have heard a lot of people say to make sure the power supply is plugged into the wall so you can establish a good ground when you hold the case.
Someone up above suggested unplugging the computer, which, in effect, is unplugging the power supply.
I wonder which is better.




Good advice + great people = tek-tips

 

[edfair]

The damage comes from the discharge when you draw the spark, even though it may not be seen.

Both can be at many hundreds or thousand of volts (static potential) with regard to earth ground but as long as there is no potential difference between the board and the person there will be no discharge.

The whold thing about static discharge is overblown. Granted that there were chips in the late 1970s that would die if you looked at them crosseyed, the later designs have resolved the issues to the extent that once mounted on a board they are mostly immune to shock damage. This is not to say that you can practice scuffing your shoes then touching the board and get by with it, but reasonable precautions will suffice.

All good workbenches should be protected but that protection should be checked regularly to make sure that it is still effective and not degraded to the extent of danger to life.

As far as the use of the grounding supplied by the power cord, the risk of plugging or unplugging a live keepalive circuit presents more of a danger to the board than the possible static damage by not using it.

The key word in all this is "reasonable".






Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[garebo]

Well, i personally believe in unplugging the computer from the wall plug via the power supply, should have said that i guess.
Reasonable is a good word. As long as a person has grounded themself on the case then all will be well. Each time you move around a lot just hold the case and keep a hand or body part touching the case as much as you can and all will be well.
Most of the time the probs come when its a very dry climate
and a person has carpeting. But usually they know as they get a shock when grabbing a door handle or other metal objects.


Good advice + great people = tek-tips

 

[mainegeek]

I would offer the same advice mentioned above and perhaps keep your shoes on as well.

 

[micker377]

mainegeek:
I always take my shoes off. Synthetic shoe material scuffing on carpet, builds up a lot more than barefoot!

 

[Aussie2]

Just read this(By Scott Mueller}
Be sure to use a properly designed commercial grounding strap do not make one yourself commercial units have a 1-meg ohm resistor that serves as a protection if you accidentally touch live power the resistor ensures that you do not become the path of least resistance to ground
Also night class it tech lecturer maintains power cord should be left plugged in but power off at wall socket by grouding self to case only evens potential providing a earth via power cable gives continulty to ground I might also add that this particular lecturers system of choice is a p2 500mhz win95 so I will let you guys make your own conclusions

 

[edfair]

Scott Mueller also wrote the book for people who are not capable of building their own "protected" grounding system and are therefore more at risk of blowing a board.

Suspect that the lecturer might be the same one I taught with that never figured out why clone machines didn't get to basic the same way IBM machines did. But you have to recognize that the instructor might be right about his machine. More of mine are under 500 than are over 500 and it seems I use the slower ones more often.

Ed Fair
Give the wrong symptoms, get the wrong solutions.