PC Technician Chapter 2: Safety and Protecting Against ESD

Static electricity

*Static electricity* is the accumulation of an electric charge (produced by friction) on a non-grounded object. The static charge on the surface of a non-grounded object can jump when it contacts the surface of any grounded object. This electric discharge is known as *electrostatic discharge (ESD)*. ESD can be very destructive to a computer. The threat of ESD begins when the fragile components (including the processor, hard drives, memory, mobo, and expansion cards) inside the computer are exposed. Damage can occur simply by placing a fingertip too close to a component inside an open computer case. ESD charges can travel through wires and into components, where the wires can explode or fuse together, causing the components to fail. ESD can cause immediate failure of components, or could gradually degrade components, causing only intermittent problems. It takes very little ESD to damage a component. -A discharge of as little as 300 volts can damage a component, but 3,000 volts or more of ESD must occur before you can even feel it.

What is the proper way to lift heavy objects?

-Bend your knees and keep your back straight, using your legs to lift objects. -If your job requires frequent lifting, wear a back brace for added protection. -Use carts and other tools when moving heavy objects for any significant distance. -If necessary, ask for help when lifting or moving heavier objects. -Follow the weight limitation guidelines defined by your employer.

Which specific computer components require special care that will protect your safety when handling them?

-Components such as the CPU heat sink and fan, the printing head of a dot matrix printer, or components inside a laser printer can be hot. After turning off a computer, allow components to cool sufficiently before servicing to prevent burns. -Power hazards can cause electrical shock and burns. Before handling a system component, make sure that it is powered off and that the main power cord is unplugged from the wall socket. Ensure that the grounding pin on a PC power plug is intact. Because newer power supplies constantly pull power from the socket, unplug the system before working on internal components. The power inverter (power supply) converts AC current to DC current. The power supply can retain an electrical charge, even when not plugged in. Replace faulty power supplies instead of trying to repair them. Avoid opening the power supply which houses a capacitor (stores a large charge of electricity). Capacitor -Be sure to discharge capacitors or turn the equipment over to qualified personnel for servicing. Similarly, exercise caution when working with the DC converter in a laptop display. ESD and High Voltage Exercise great care when working with electricity. ESD wrist straps not only protect components, but can reduce the chance of accidental electrical shock. Properly ground yourself before working with components. Do not use an ESD wrist strap when working with monitors, power supplies, laptop LCD panels, or other high-voltage components. You should be especially careful when wearing jewelry because it readily conducts electricity and could cause burns or even electrocution. Peripherals can present a safety hazard to you. Do not use a regular multimeter or other electrical testing equipment to measure charge inside a monitor. Never clean the monitor's glass with a liquid solvent while the monitor is powered on. Some studies suggest that laser printers emit tiny particles which could be dangerous when inhaled. As a precaution, do not locate laser printers immediately next to desks, and keep the area ventilated. Avoid handling leaky batteries. The leaking electrolytes can be harmful if they get into your eyes. Never look into the end of a fiber optic networking cable. Laser light can damage your eyes.

What steps can you take to reduce ESD if you do not have the proper equipment handy?

-Keep the relative humidity in the room high, ideally around 70%, and temperature between 72-77 degrees. -The key is to avoid dry air in the computer repair location to prevent ESD. -Use antistatic mats under the PC and on the floor. -Discharge yourself before touching any computer component. -When touching anything inside the computer, wear an antistatic wrist strap that is attached with an alligator clip to the metal PC chassis. -Ground both yourself and the computer to the same ground. This provides a single path for the flow of electrical potential. -Use static resistant materials to handle computer components. -Never touch the metal connectors on a circuit board. -Keep the computer repair location free of materials that accumulate electric charges (e.g., plastic or Styrofoam). -Store sensitive components in static shielding bags (also called antistatic bags; they are usually tinted gray). Static resistant bags are not nearly as effective (usually tinted pink or blue). If a wrist strap is unavailable, keep your body in constant contact with the metal frame when working inside the computer.

Measures to protect you against ESD.

-Keep the relative humidity in the room high, ideally around 70%, and temperature between 72-77 degrees. The key is to avoid dry air in the computer repair location to prevent ESD. -Use anti-static mats under the PC and on the floor. -Discharge yourself before touching any computer component. -When touching anything inside the computer, wear an antistatic wrist strap that is attached with an alligator clip to the metal PC chassis. -Ground both yourself and the computer to the same ground. This provides a single path for the flow of electrical potential. -Use static resistant materials to handle computer components. -Never touch the metal connectors on a circuit board. -Keep the computer repair location free of -materials that accumulate electric charges (e.g., plastic or Styrofoam). -Store sensitive components in static shielding bags (also called anti-static bags; they are usually tinted gray). Static resistant bags are not nearly as effective (usually tinted pink or blue). -If a wrist strap is unavailable, keep your body in constant contact with the metal frame when working inside the computer. -Unplug the system before working on internal components. Do not rely on the power cord for an electrical ground.

What is the MSDS? When would the information that it provides be important?

MSDS describes safe handling and disposal procedures for dangerous materials and can provide you with the knowledge to resolve an uncertain situation.

What is the difference between a static shielding bag and a static-resistant bag?

Static shielding (aka antistatic) bags are usually tinted gray). Static resistant bags are not nearly as effective (usually tinted pink or blue).

How can ESD be a hazard to electronic computer components?

The threat of ESD begins when the fragile components (including the processor, hard drives, memory, motherboard, and expansion cards) inside the computer are exposed. Damage can occur simply by placing a fingertip too close to a component inside an open computer case. ESD charges can travel through wires and into components, where the wires can explode or fuse together, causing the components to fail. ESD can cause immediate failure of components, or could gradually degrade components, causing only intermittent problems. It takes very little ESD to damage a component. A discharge of as little as 300 volts can damage a component, but 3,000 volts or more of ESD must occur before you can even feel it.