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Chapter 1. PC Technician Essentials > Preventing Electrostatic Discharge

Preventing Electrostatic Discharge

Electrostatic discharge (ESD) occurs when two objects of different voltages come into contact with each other. The human body is always gathering static electricity, more than enough to damage a computer component. ESD is a silent killer. If you were to touch a component without proper protection, the static electricity could discharge from you to the component, most likely damaging it, but with no discernable signs of damage. Worse yet, it is possible to discharge a small amount of voltage to the device and damage it to the point where it works intermittently, making it tough to troubleshoot. It only takes 30 volts or so to damage a component. On a dry winter day, you could gather as much as 20,000 volts when walking across a carpeted area! Ouch! There are several ways to equalize the electrical potentials, allowing you to protect components from ESD:

  • Use an antistatic wrist strap— The most common kind is inexpensive and only takes a moment to put on and connect to the chassis of the computer (an unpainted portion of the frame inside the case). By using an antistatic wrist strap, you are constantly discharging to the case’s metal frame instead of to the components that you handle. Of course, the chassis of the computer can only absorb so much ESD, so consider another earth-bonding point to connect to or try to implement as many other antistatic methods as possible. Most wrist straps come equipped with a resistor (often 1 megaohm) that protects the user from shock hazards when working with low-voltage components.

    More advanced types of wrist straps are meant to connect to an actual ground; a ground strip or the ground plug of a special dedicated AC outlet. These are used in more sophisticated repair labs. Do not attempt to connect the alligator clip of a basic wrist strap (purchased at an office store), to the ground plug of an outlet in your home.

  • Touch the chassis of the computer— Do this to further discharge yourself before handling any components. This is also a good habit to get into for those times when an anti-static strap is not available.

  • Use an antistatic mat— Place the computer on top of the antistatic mat and connect the alligator clip of the mat to the computer’s chassis in the same manner that you did with the wrist strap. (Some people stand on the mat and connect it to the computer.)

  • Use antistatic bags— Adapter cards, motherboards, and so on are normally shipped in antistatic bags. Hold on to them! When installing or removing components, keep them either inside or on top of the bag until you are ready to work with them.


  

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