Low End PC

Practice Safe Computing

How to work on your computer without zapping it to death

- 2002.04.04

In most books about fixing your own computer, and also in curriculum for preparing for the CompTIA A+ exam, you don't find guidelines for preventing electrostatic discharge at the front of the book. This is unfortunate, because ESD (let's call it static, just to make things simple and easy) is the cause of so many problems that manifest themselves in a computer.

You've all experienced that "zap!" feeling you get when your body picks up a static charge and you touch something metal. What you might not realize is that with that "zap!" you just discharged 20,000 volts or so of electrical energy. The amperes are extremely low, so no trouble at all with potential electrocution. But yeah, that's 20,000 volts of static electricity.

I cannot stress this enough: It doesn't take any more than a few volts to fry computer circuitry. That's way below the range where you actually feel it. And if something isn't damaged to the point of immediate failure, it can be damaged enough to cause transient problems that will have you tearing your hair out trying to chase it down. So you'd better make sure that you are protected before you open up your computer.

Here are Ms. Geek's 5 commandments for static prevention.

  1. Thou shalt not wear synthetic fabrics or wool when thou workest on a computer.
  2. Thou shalt wear rubber soled shoes, not leather-soled shoes, when thou workest on a computer.
  3. Thou shalt wear thy static strap at all times when working on a computer, except if thou art foolhardy enough to open up your monitor to "fix" it.
  4. Thou shalt consider buying an antistatic mat to lay parts on while thou art working. Failing this, thou shalt keep the parts resting on antistatic foam or an antistatic bag.
  5. Thou shalt work on thy computer in an uncarpeted room whenever possible. If thou canst not avoid working on a computer in a carpeted room, thou shalt be doubly careful with antistatic precautions in this environment.

The first and second commandment can be taken together. Synthetic fabrics are notorious for building up static. You know those commercials for "Static Guard" spray where people are shown with clothes adhering to their bodies? That's an object lesson in how easily synthetic fabrics build up a static charge. Wool is also not a good choice, because it is made of animal fur and easily charged.

Cotton is your best choice because it's close to being static-neutral. Rubber is a static insulator, so it's a good choice for shoe soles in a static-controlled environment.

The third one takes a bit of explanation. There are two kinds of static straps: one is the kind that clips to a grounded metal object, the other is a special kind that dissipates static into the air via ionization. I like the latter just for the freedom it gives you - it's great not being tethered to something while you're working on a computer. The corded type is the kind you want to use if you live in a super-arid climate like Arizona, New Mexico, or Texas (or northern climes in those dry, cold winters), because the ionization static straps will not work in low-humidity conditions. Actually if humidity gets below 25% you would be wise to put off any sort of computer construction, repair, or upgrade project, period. The corded type of static strap is available in any Radio Shack or other store that sells electronic components. The cordless type is available on the Internet at several stores. Here are two links:

The only time you don't want to be wearing a static strap is when you have a monitor open and you're working on the components. In order for your monitor to "wake up" quickly, it holds lots of electricity in a capacitor. It's several thousand volts at enough amperage to kill you! Not a good situation.

Most of the time you don't want to open a monitor up. Unfortunately, with all-in-one computers like the Mac Classic, the CRT iMac, the Mac 52xx series, and the G3 All-In-One, you have no choice in the matter. There are a few PCs built this way, too, but they are few and far between - and Apple usually gets on the manufacturer's case if their computers get too close to their iMac's design for comfort.

The fourth commandment is easy. Antistatic mats are great for protecting your components against static discharge. They consist of a mat with insulating materials on the top and bottom with conductive materials in the middle of the "sandwich." The ground cord is attached to the conductive center and is clipped to a grounded metal object. They are not really expensive but are a bit more pricey than some might be comfortable with. They are worth it if you do a lot of work on your own computers. Here's a link to a source for them:

Failing that, the antistatic bags and antistatic foam computer parts are packaged with will provide you more protection than nothing. First, keep parts in their static-resistant packaging for as long as you possibly can before taking them out. Second, keep those bags and foam!

Once you take a motherboard or an expansion card out of your computer, its next stop should be a static-resistant bag. The silver ones work best; use the pink ones only if you have absolutely no silver bags left. You might want to even consider buying some to make sure you never run out. Buy the big ones so that you can keep them on hand for motherboard swaps.

Ideally you should use antistatic protection to secure your workspace against static, which brings us to commandment five. Worst of all for static buildup is a carpeted surface, like what you find in most homes. Linoleum and wood covered floors provide some protection, but are still not great. The best antistatic surface is a bare concrete slab, like what you would find in your garage. Even there, ideally you should work in a protected environment. There is an industry group, the ESDA, which has lots of good information about static protection on their website. Here is the example they give of an ideal static-protected environment:

ESDA ideal work station

Note that there is a protected surface on top of the workbench and another for you to stand on. There is just about everything you need to create a protected working environment at www.anti-staticmat.com. This can get pricey, so if you are not doing computer repair professionally, maybe all this would be overkill. For the casual computer "shade tree mechanic" just making sure you do your work in your garage or on your kitchen table would be fairly sufficient.

If you have to work on a carpeted surface, you have to be really careful about protection against static. There are sprays you can use on carpet which you can purchase, and a good homemade static protection spray even recommended by the US Military can be made with one part fabric softener, like Downy, to three parts water. Put that in a spray bottle and spray it over your carpet from time to time. It's good practice to make this a part of your cleanup routine in the room you use your computer in.

Also make sure you have your static strap on at all times when you have the case off your computer for any reason, and consider getting a static protection mat for placing parts on.

A few more tips: Always pick up expansion cards by the metal bracket. It's designed to ground the circuit board. Pick up circuit boards that don't have brackets, like sticks of memory and motherboards, by the edges that do not have contacts on them. Crucial.Com has a great tutorial on how to install RAM you should read when you get the chance. In an emergency situation, you can keep yourself grounded by holding one hand on a computer's power supply while uninstalling/installing parts. This is not ideal by any means, but it's better than nothing.

Here's some more good info on static, starting with the most basic and building to the most technical:

Next article: More about the beauty of bitty boxen. LEPC

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