11.1 Troubleshooting Basics
11.1.11 Electrostatic issues
Computers primarily use two types of chips. These include the transistor-transistor logic (TTL) and the metal oxide semiconductor (MOS). The normal operating level of these chips, in terms of voltage, is 2.8V, 3.3V, or 5V. Normally, TTL chips run at 5 V and CMOS chips run at 3.3V or less.

Today, computer components are small and operate at fast speeds. These characteristics make computer components susceptible to Electro Static Discharge (ESD). ESD is the flow of current between two objects with different electrostatic potentials. For an electrical discharge to be destructive to a computer, it does not have to release high levels of energy. ESD can destroy internal components with a relatively low release of voltages. Most computer components can be damaged or completely destroyed with a charge between 10 and 20 volts. Humans cannot feel much below 30 volts of static electricity. Computer technicians or end users can unknowingly damage the computer. For this reason, it is important to consider ESD in the workspace. The best way to protect against ESD is to use precautionary tools and measures in work areas.

Release static electricity by either touching the metal case or wearing a wrist strap before contacting any internal components. However, static electricity can build up while working on the computer system. To help prevent against the harmful affects of ESD, touch the metal computer case throughout the troubleshooting process.

Prevention Measures
ESD is a product of the surrounding environment. ESD is more likely to develop in a cold, dry environment. A warm, damp environment will help reduce ESD. Humidifiers can be introduced into the environment to help provide a damp environment.

Another way to protect against ESD is by using preventive tools:

  • Wrist Straps – When handling computer components, use a wrist strap to guard against ESD. An anti-static wrist strap works by grounding the technician to the component they are working on. The technician and computer component will have the same electrical charge and static electricity will not flow between the two. An anti-static wrist strap must stay in constant contact with the technician's bare skin.
  • Bench and Floor Mats – Bench and floor mats help reduce static electricity. As the technician is moving around, the floor mat will drain any static electricity. Floor mats should have a grounding strap connected to a ground and should be cleaned frequently for effective prevention of ESD. Also, avoid plastic, vinyl, carpet, and finished or waxed surfaces in the work area.
  • Grounding – Workbenches should be grounded to dissipate static electricity. This will help prevent against the damages of ESD. Also, keep the workbench clear of any coffee, tools, and stereo equipment.
  • Anti-Static Packaging – Proper handling care should be taken to protect against ESD. Handle computer parts only at the edges. If a static release occurs directly with circuitry, the part might fail. Also, parts should be stored in antistatic bags or bins to protect against ESD. When removing computer components, place the parts directly in an anti-static bag.
  • Anti-static Sprays – Using anti-static sprays in the workplace helps reduce static electricity. Apply the anti-static spray with a soft cloth to the work area.

ESD is very important. Different ways to cope with ESD have been discussed throughout the previous chapters. ESD was discussed in Chapter 10, "Preventive Maintenance.