Assessments - 1, GPA: 4
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Flat-bladed screwdriver . Magnetic screwdriver . Phillips P0 and P1 screwdrivers Service considerations The following sections include some of the considerations that you must keep in mind during disassembly and assembly procedures. NOTE: As you remove each subassembly from the computer, place the subassembly (and all accompanying screws) away from the work area to prevent damage. Plastic parts CAUTION: Using excessive force during disassembly and reassembly can damage plastic parts. Use care when handling the plastic parts. Apply pressure only at the points designated in the maintenance instructions. Cables and connectors CAUTION: When servicing the computer, be sure that cables are placed in their proper locations during the reassembly process. Improper cable placement can damage the computer. Cables must be handled with extreme care to avoid damage. Apply only the tension required to unseat or seat the cables during removal and insertion. Handle cables by the connector whenever possible. In all cases, avoid bending, twisting, or tearing cables. Be sure that cables are routed in such a way that they cannot be caught or snagged by parts being removed or replaced. Handle flex cables with extreme care; these cables tear easily. Preliminary replacement requirements 29 Drive handling CAUTION: Drives are fragile components that must be handled with care. To prevent damage to the computer, damage to a drive, or loss of information, observe these precautions: Before removing or inserting a hard drive, shut down the computer. If you are unsure whether the computer is off or in Hibernation, turn the computer on, and then shut it down through the operating system. Before handling a drive, be sure that you are discharged of static electricity. While handling a drive, avoid touching the connector. Handle drives on surfaces covered with at least one inch of shock-proof foam. Avoid dropping drives from any height onto any surface. After removing a hard drive, an optical drive, or a diskette drive, place it in a static-proof bag. Avoid exposing a hard drive to products that have magnetic fields, such as monitors or speakers. Avoid exposing a drive to temperature extremes or liquids. If a drive must be mailed, place the drive in a bubble pack mailer or other suitable form of protective packaging and label the package “FRAGILE.” 30 Chapter 4 Removal and replacement procedures Grounding guidelines Electrostatic discharge damage Electronic components are sensitive to electrostatic discharge (ESD). Circuitry design and structure determine the degree of sensitivity. Networks built into many integrated circuits provide some protection, but in many cases, ESD contains enough power to alter device parameters or melt silicon junctions. A discharge of static electricity from a finger or other conductor can destroy static-sensitive devices or microcircuitry. Even if the spark is neither felt nor heard, damage may have occurred. An electronic device exposed to ESD may not be affected at all and can work perfectly throughout a normal cycle. Or the device may function normally for a while, then degrade in the internal layers, reducing its life expectancy. CAUTION: To prevent damage to the computer when you are removing or installing internal components, observe these precautions: Keep components in their electrostatic-safe containers until you are ready to install them. Use nonmagnetic tools. Before touching an electronic component, discharge static electricity by using the guidelines described in this section. Avoid touching pins, leads, and circuitry. Handle electronic components as little as possible. If you remove a component, place it in an electrostatic-safe container. The following table shows how humidity affects the electrostatic voltage levels generated by different activities. CAUTION: A product can be degraded by as little as 700 V. Typical electrostatic voltage levels Relative humidity Event 10% 40% 55% Walking across carpet 35,000 V 15,000 V 7,500 V Walking across vinyl floor 12,000 V 5,000 V 3,000 V Motions of bench worker 6,000 V 800 V 400 V Removing DIPS from plastic tube 2,000 V 700 V 400 V Removing DIPS from vinyl tray 11,500 V 4,000 V 2,000 V Removing DIPS from Styrofoam 14,500 V 5,000 V 3,500 V Removing bubble pack from PCB 26,500 V 20,000 V 7,000 V Packing PCBs in foam-lined box 21,000 V 11,000 V 5,000 V Preliminary replacement requirements 31 Packaging and transporting guidelines Follow these grounding guidelines when packaging and transporting equipment: . To avoid hand contact, transport products in static-safe tubes, bags, or boxes. . Protect ESD-sensitive parts and assemblies with conductive or approved containers or packaging. . Keep ESD-sensitive parts in their containers until the parts arrive at static-free workstations. . Place items on a grounded surface before removing items from their containers. . Always be properly grounded when touching a component or assembly. . Store reusable ESD-sensitive parts ...
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