Rosewill Computer Case 422 Informações Técnicas descarregar pdf (Página 39)

122

Chapter 4 • Disassembly and Power

computer is a good idea. A power supply provides a small amount of power to the motherboard

even when the computer is powered off. Always unplug the computer and use an antistatic

wrist strap when removing or replacing parts inside a computer!

EMI (Electromagnetic Interference)

EMI (electromagnetic interference, sometimes called EMR, for electromagnetic radiation) is

noise caused by electrical devices. Many devices can cause EMI, such as a computer, a pencil

sharpener, a motor, a vacuum cleaner, an air conditioner, and fluorescent lighting. The electri-

cal devices around the computer case, including a CRT-type monitor and speakers, cause more

problems than the computer.

A specific type of electromagnetic interference that affects computers is RFI (radio fre-

quency interference). RFI is simply those noises that occur in the radio frequency range.

Anytime a computer has an intermittent problem, check the surrounding devices for the

source of that problem. For example, if the computer goes down only when the pencil sharp-

ener operates or when using the optical drive, EMI

could be to blame. EMI problems are very hard to track

to the source. Any electronic device including comput-

ers and printers can be a source of EMI/RFI. EMI/RFI

can affect any electronic circuit. EMI can also come

through power lines. Move the computer to a different

wall outlet or to a totally different circuit to determine

if the power outlet is the problem source. EMI can also

affect files on a hard drive.

Disassembly

Before a technician disassembles a computer, several steps should be performed or considered.

The following disassembly tips are helpful:

• Do not remove the motherboard battery, or the configuration information in CMOS will

be lost.

• Use proper grounding procedures to prevent ESD damage.

• Keep paper, a pen, a phone, and a digital camera nearby for note taking, diagramming,

and photo taking. Even if you have taken apart computers for years, you might find

something unique or different inside this one.

• Have ample flat and clean workspace.

• When removing adapters, do not stack the adapters on top of one another.

• If possible, place removed adapters inside a special ESD protective bag.

• Handle each adapter, motherboard, or processor on the side edges. Avoid touching the

gold contacts on the bottom of adapters. Sweat, oil, and dirt cause problems.

• Remember that hard drives require careful handling. A very small jolt can cause damage

to stored data.

• You can remove a power supply, but do not disassemble a CRT-style monitor or power

supply without proper training and tools.

• Document screw and cable locations. Label them if possible.

Tools

No chapter on disassembly and reassembly is complete without mentioning tools. Tools can be

divided into two categories: (1) those you should not leave the office without and (2) those that

are nice to have in the office, at home, or in the car.

Replace empty slot covers

To help with EMI and RFI problems, replace slot

covers for expansion slots that are no longer being

used. Slot covers also keep out dust and improve

the air flow within the case.

Tech

Tip

1 2 ... 34 35 36 37 38 39 40 41 42 43 44 ... 149 150

Comentários a estes Manuais

Sem comentários

Rosewill Computer Case 422 Informações Técnicas Página 39

Comentários a estes Manuais