When repairing computers, like anything else, safety is always first. There are few tricks and tools of the trade to keep you safe and help with the repair of any computer. This section will start with things to look out for to keep you safe and end with the tools of the trade to help you complete your task.
Electrostatic Discharge (ESD)
Electrostatic discharge (ESD) is the release of static electricity when two objects come into contact. Familiar examples of ESD include the shock we receive when we walk across a carpet and touch a metal doorknob and the static electricity we feel after drying clothes in a clothes dryer. A more extreme example of ESD is a lightening bolt. While most ESD events are harmless, it can be an expensive problem in many industrial environments.
ESD first requires a build-up of an electrostatic charge. This occurs when two different materials rub together. One of the materials becomes positively charged; the other becomes negatively charged. The positively-charged material now has an electrostatic charge. When that charge comes into contact with the right material, it is transferred and we have an ESD event. The heat from the ESD event is extremely hot, although we do not feel it when we are shocked. However, when the charge is released onto an electronic device such as an expansion card , the intense heat from the charge can melt or vaporize the tiny parts in the card causing the device to fail. Sometimes an ESD event can damage a device, but it continues to function. This is a called a latent defect, which is hard to detect and significantly shortens the life of the device
Many electronic devices are susceptible to low voltage ESD events. For example, hard drive components are sensitive to only 10 volts. For this reason, manufacturers of electronic devices incorporate measures to prevent ESD events throughout the manufacturing, testing, shipping, and handling processes. For example, an employee may wear a wrist strap when working with devices or may wear ESD control footwear and work on an ESD floor mat that causes the electrostatic charge to go into the ground instead of into the device. Sensitive devices can be packaged with materials that shield the product from a charge.
Anti-static Tools
Anti-static tools are just as they sound. They are tools with the sole purpose of expelling static from computer, you, and the computers parts. Some of these tools include wristbands, mats, and bags.
Anti-static Wrist Strap
An anti-static wrist strap is a key piece of safety gear that helps to prevent the buildup of static electricity near sensitive electronics or other projects where static charge could damage electronics or cause safety issues. The wrist strap is often used with an anti-static mat or other type of work space covering. Special, highly conductive threads on the wrist strap lead to a ground conductor in order to discharge static electricity safely.
While users often take advantage of an anti-static wrist strap to protect items like circuit boards during construction, testing or other activities, some of these devices also qualify as personal protective equipment (PPE), where grounded anti-static devices can help protect wearers in higher voltage situations. Other common situations for using anti-static tools may be based on specific protocols. For example, when an ESD wrist strap is used to protect a PC, the ground is often attached to the computer chassis.
Manufacturers will usually provide items like a wrist strap devices in accordance with specific industry standards. Many of these items have been evaluated by Underwriter Laboratories, a prime tester of electronics handling equipment. Most products will also be marked according to maximum voltage.
Anti-static Mat
In anti-static floor mat or ground mat is an anti-static device that safeguards an individual or piece of equipment like a PC from an electrostatic discharge (ESD). Computer components that are sensitive to static electricity or ESD are motherboards, CPUs, expansion cards and memory devices.
Anti-static mats are used under keyboards or mice and may also be placed on or under other equipment. They are particularly useful when working on computer components. Once an anti-static mat is grounded, it is important not to lift the component off the mat because it will be susceptible to ESD.
An anti-static mat is designed to help lessen the effects of an electrostatic discharge (ESD) on an individual or static-sensitive component. It also assists in preventing explosions and fires when working with flammable material found in certain gases and liquids.
An anti-static mat contains a conductive material that accumulates static. Because it collects electricity, it needs to be grounded or earthed. This is accomplished by plugging it into a grounded electrical outlet.
Devices that are sensitive to an electrostatic discharge are mostly electrical components. Common modules on a PC that are electrostatic-sensitive are:
• Complementary metal-oxide-semiconductor (CMOS) chips, found in CPUs and graphic cards
• Transistor-transistor logic (TTL) chips
• Metal-oxide-semiconductor field-effect transistors (MOSFET)
• Laser diodes (LD)
• High precision resistors
• Blue-light-emitting diodes (LEDs)
Aside from an anti-static mat, there are other electrostatic devices, including anti-static straps, anti-static bags, anti-static agents and anti-static garments.
EMI (electromagnetic interference) is the disruption of operation of an electronic device when it is in the vicinity of an electromagnetic field (EM field) in the radio frequency (RF) spectrum that is caused by another electronic device.
The internal circuits of personal computers generate EM fields in the RF range. Also, cathode ray tube (CRT) displays generate EM energy over a wide band of frequencies. These emissions can interfere with the performance of sensitive wireless receivers nearby. If you have a wireless receiver of any kind and use it at the same time as you operate your personal computer, you will probably hear RF noise in the receiver that originates in the PC system.
Moderate- or high-powered wireless transmitters can produce EM fields strong enough to upset the operation of electronic equipment nearby. If you live near a broadcast station or in the downtown area of a large city, you have probably experienced EMI from radio or television transmitters. Cordless telephones, home entertainment systems, computers, and certain medical devices can fail to work properly in the presence of strong RF fields.
Problems with EMI can be minimized by ensuring that all electronic equipment is operated with a good electrical ground system. In addition, cords and cables connecting the peripherals in an electronic or computer system should, if possible, be shielded to keep unwanted RF energy from entering or leaving. Specialized components such as line filters, capacitors, and inductors can be installed in power cords and interconnecting cables to reduce the EMI susceptibility of some systems. Before performing any modifications to equipment, contact the manufacturer for technical assistance. This is especially important if modifications might void an existing warranty, and it is imperative with medical devices of any kind.
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