Rosewill Computer Case 422 Technické informace stáhnout pdf (Strana 81)

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Chapter 4 • Disassembly and Power

Chapter Summary

• Wearing a wrist strap or staying in contact with unpainted metal keeps you and the

computing device at the same electrical potential so you won’t induce current into any

part and weaken/damage it.

• EMI and RFI cause issues. Move the computer or the offending device and replace all

slot covers/openings.

• When removing parts, have the right tools, lighting, antistatic items, and ample work

space. Take notes. Don’t use magnetized tools. Avoid jarring hard drives.

• Be careful installing an I/O shield and be aware of standoffs when dealing with the

motherboard.

• Laptops and mobile devices frequently have compartments for memory and expansion

card. These devices frequently have plastic parts that must be removed. A scribe helps

with prying plastics and covers off. Laptop speakers and DC power plug frequently have

cables that run along the back or sides of the device. Keep screws separated and take

notes for any parts removal.

• Ribbon cables have a colored stripe indicating pin 1. Pin 1 of a cable must attach to pin

1 of a connector.

• Preventive maintenance procedures prolong the life of the computer. Vacuum before

spraying compressed air.

• An MSDS describes disposal and storage procedures and contains information about

toxicity and health concerns. Cities/states have specific disposal rules for chemicals, bat-

teries, CRTs, electronics, and so on. Always know the disposal rules in the area where

you work.

• AC power goes into the power supply or mobile device power brick. DC power is pro-

vided to all internal parts of the computing device. AC and DC voltage checks can be

done and only with DC power does polarity matter. Use the highest meter setting pos-

sible with unknown voltage levels. Power is measured in watts.

• Continuity checks are done on cabling and a good wire shows close to 0 ohms.

• A power supply converts AC to DC, distributes DC throughout a unit, and provides cool-

ing. The power supply must be the correct form factor and able to supply the current

amount of wattage for a particular voltage level such as +5V or +12V. Multiple “rails”

are commonly available for +12V since the CPU commonly needs its own connection.

The number and type of connectors vary, but converters can be purchased.

• Li-ion batteries are used with mobile devices. If a device must be attached to AC power

or a USB port to work, replace the battery with one of with the correct DC power jack,

appropriate DC voltage level, and current (amperage) equal to or higher than the origi-

nal power brick.

• Conserve mobile device power by adding more RAM, turning off wireless/Bluetooth,

configuring power options, reducing screen brightness, and avoiding temperature

extremes.

• You use ACPI to control power options through BIOS and the operating system. Wake

on LAN and Wake on Ring are power features that allow a device to be powered up from

a lowered power condition for a specific purpose.

• An AC circuit tester, multimeter, and power supply tester are tools used with power

problems.

• Power issues include overvoltage conditions such as a surge or spike that can be helped

with surge protectors, power conditioners, and UPSs. Power conditioners and UPSs help

with undervoltage conditions such as a sag. A UPS is the only device that powers a com-

puter when a blackout occurs.

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Rosewill Computer Case 422 Technické informace Strana 81

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