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Section 1: Preparing for Service
Static Control Modern PCs depend on extremely complex integrated circuits, and those chips are very sensitive to Electrostatic Discharge (ESD). Unfortunately, static electricity is commonplace and is generated constantly by such innocent means as passing a comb through our hair or putting on a sweater. When ESD is allowed to discharge through a chip, the chip is destroyed. No outward signs of ESD damage occur: no smoke, no fire, and rarely any shock or other physical sensation. Still, the damage is quite real. ESD is controlled by a combination of grounding, protective materials, and environmental management. Here are some tips to prevent ESD:
• Use wrist straps. Grounding wrist straps are the first line of defense against ESD. They attach to your wrist and connect to a grounded surface or outlet through a wire. When properly connected, a wrist strap "bleeds off" any charge on your body and clothing, making it safer to handle delicate electronics.
• Use anti-static containers. You have probably noticed that all delicate electronics come packaged in blue or pink bags. These act as "Faraday cages" that dissipate charges before they can reach the device contained inside. Always keep devices inside anti-static containers until you are ready to actually install them, and then place any removed device into an anti-static container immediately.
• Use an anti-static mat. A mat works like a wrist strap by connecting to ground and bleeding off any accumulated charges. You can place boards, chips, or single inline memory modules (SIMMs) safely on a properly connected anti-static mat without having to place them in containers.Anti-static mats are very popular on PC repair workbenches where sensitive items are regularly installed and removed.
• Use anti-static chemicals. Monitor screens, most synthetic surfaces, and virtually all plastic enclosures are major sources of ESD. When properly and regularly applied, anti-static chemicals can go a long way toward preventing ESD damage from accidental or casual contact with sensitive electronics.
• Manage temperature and humidity. Static builds up discharges easily in cool, dry environments. Work in a warm area with adequate relative humidity (RH). Use a humidifier if necessary to maintain adequate RH.
Electricity Control
PCs and their peripherals use a raw alternating current (AC) as a power source. Although the myriad of plugs, outlets, and line cords used today are generally regarded as quite safe for end-users, technicians must often work in close proximity to exposed circuitry. In reality, the odds of electrocution are actually quite slim, but electricity can injure or kill when handled carelessly.
Follow these guidelines to prevent any electrical mishaps:
• Keep the PC unplugged when working inside at. As a rule, unplug the PC (don't just turn it off) during upgrades or repairs.
• Use one hand only for "hot" measurements. If you must make measurements or probe around inside a powered system (especially inside the power supply), keep one hand behind your back. If you should contact a live wire, there is no pathway through your heart...
