I will be building a computer this weekend, but don’t have an anti-static wrist strap. Could I tape a peice of electrical wire to my arm, and then to the case? I’m thinking of speaker wire, because of it’s flexability.
Also, when assembling a computer, should I have the case grounded as well before handling any parts?
I’m just looking for an alternative because I honestly don’t know where I could buy a wrist strap.
If you’re careful, you don’t need a wrist strap. Just make sure you are wearing things like rubber soles, a short-sleeve cotton shirt, and the like. Make sure to ground yourself constantly on the case. Personally, I’ve never shorted out a computer part, and I’ve never used a wrist strap.
Wrist grounding straps have a high value resistor in series with the grounding wire. This serves two purposes. It provides a high voltage drop and lower discharge rate for any static discharge, that is to say no big spark. If you don’t have this you’ve defeated the purpose of using a grounding strap in the first place. It is also a safety issue. In some situations you may accidentally touch a high potential point with your right hand while your left hand is grounded making for a current path through your heart. This is what electricians call a bad thing. If this happens you may need the immediate attention of a mortician.
I’m not always good about using a grounding strap but it’s cheap insurance.
Do you have Radio Shack stores up there? They sell inex[emsove wrist straps.
I agree with the others. You can ground yourself to the case by touching the power supply case before you touch anything else inside, but don’t attach yourself to the case with a straight wire. In the event of a short too much current could flow through you. Also, handle components by the edges, doing your best to not touch any electrical contacts at all. There’s usually enough space around the edges of the circuit boards to do this.
Whatever you do, don’t leave the computer plugged in while working on it. The newspaper/idiot/columnists repeatedly suggest this but it is a bad idea. Special note: unplugged means the plug is pulled out, get it? Unplugged, there is no voltage inside a computer case that could harm you. (This is not true for other devices such as CRTs, TVs, and microwaves.) As far as harming you, it all comes down to static electricity, which isn’t going to cause a heart attack.
Lot’s of ways to mess up the computer though. E.g., dropping a metal object (such as a screw) into the case can short out the CMOS backup battery, which is Not A Good Thing. So don’t do that.
You and the computer merely have to be at the same potential. Just touch bare metal on the case repeatedly or attach the wrist strap to an unpainted case point.
I think the OP said that he was building it from scratch, but in any case, there is often a way to discharge any residual power. On my Dell it’s holding the power button in for something like 5 or 8 seconds–I just normally keep it depressed the same amount of time it takes to force an ATX system to shut down, which I think is 8 seconds.
Even better (unfortunately) - wear cotton clothing. It absorbs moisture, and so creates a slightly conductive layer around you, dissipating static. (It’s why heavy cotton lab-coats are seen in electronics workshops/factories).
Other than that…ftg commented on the plug/unplug issue. The reason for recommending you leave it plugged in (but fully switched off, including the switch at the back) is that it keeps the case grounded. If you unplug, you need to ground yourself somewhere else, typically a cold water pipe. And if the computer is switched off properly, and assuming no problems with electrical wiring, then it’s fine to keep it plugged in.
It is not fine to leave it plugged in. You unplug the computer so that while you are working on it you don’t accidentally drop parts into the power supply or brush a screw driver against something powered in the computer. In most modern computers there is something powered when the computer is plugged in.
You need to ground yourself with respect to the computer parts. Not ground from a water pipe unless the computer is at that potential. The way that electronics companies work on electronic equipment is: They have a bench with a grounded conductive matt on it. This matt actually have a relatively high amount of resistance in it so that when you set electronics on the matt the charge is dissipated slowly so that there is never a very high current. The technician will be grounded through a resistive wrist strap or ankle strap. The electronics will not be plugged in.
You must have different power supplies that the ones I have seen. All of the power supplies I have seen have slots along the sides of the power supplies. Also most of the mother boards I have seen have front power switch plugging into the mother board. So there must be some amount of power so that the switch can turn on the power supply. Many mother boards are capable of being powered up from commands over the ether net cards. It is really somewhat irresponsible of you to advocate working on a computer while it is plugged in. You don’t get any benefit from have the computer plugged in and there is a small risk of damaging the computer or yourself.
It would be easy enough to take an old power cord and cut off the 2 prongs for the power wires, but leave the ground conductor intact. Using that cord would then keep your PC connected to the house electrical ground. Would this be a useful thing to do?
Personally, I’ve worked on PC’s a lot without a grounding strap, and never had a problem. I just make sure to ground myself frequently. When handling expensive components, like memory & CPU, I try to keep 1 hand grounded against the power supply case while installing it with the other.
P.S. If you do make such a special cord, it’s probably a good idea to mark it – prominently – like orange tiger stripes on both ends. Otherwise, someday someone will use it for a power cord, and wonder why their computer won’t work at all!
Clearly we’re talking about different power supplies. Every modern one I’ve seen has a master switch, which ends up somewhere inaccessable on the back panel, which cuts out everything - front panel switches, remote powerup, the lot. Maybe there’s differences with different electrical safety or other standards. But with one of these, there’s no way of doing any harm to anything. And indeed, you could drop anything into the supply and probably do no harm (although you’d need to find a way to get it out again!)
Yup. I have taken a PS apart, and the common wire goes to the transformer, and the hot wire goes to the hard switch first before doing anything else. Even if plugged in, if that switch on the back of the PS is off, no electricity is flowing anywhere. Plus, the slots are usually too small to get a screw into unless you really try. In addition, since he’s building from scratch, he won’t have the PS plugged into the mobo and the mobo hooked up to the power switches until the very end, when he plugs everything in just before powering on to see how badly he f*cked it up.
(At least that’s what my experiences tend to be.)