Proper Procedures for Replacing Hardware

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The most basic task in adding or replacing hardware is in physically installing the device. There are three general classes of hardware, each of which requires different procedures: external devices, internal cabled devices (like hard disks and CD-ROM drives), and internal expansion cards. A few devices straddle the lines in some way.

External devices are plugged into the computer through an external port, such as an RS-232 serial port, a parallel port, a SCSI port, or a USB port. Many, but not all, of these devices also require power from a wall outlet, so the device itself has at least two cables. External connectors are usually shaped in such a way that they can only be plugged in one way, so it's impossible to plug the device in backward. Most devices should only be attached when the computer's and the device's power are turned off. USB devices, however, can be safely attached and detached when the power is turned on.

Internal cabled devices typically attach to the motherboard or an expansion card. They usually require connecting at least two cables: a power cable and a data cable. Power cables are keyed to prevent accidental backward insertion, as are some data cables. Some data cables, though, lack this keying. If you must use such a cable, check for a colored stripe along one edge, and insert it to match up with the "pin 1" markings on both the device and the motherboard or card. You should always power off a computer before attaching internal cabled devices.

Internal cabled devices are usually mounted to the computer's case using screws. Details vary from one computer to another. Sometimes you may need to partially disassemble a system to reach the screws, which can be a nuisance. For instance, I've seen mini-tower systems that require you to partially remove the motherboard to reach screws for 3.5-inch hard disks. If you've removed screws but you can't remove a drive, look for other areas (even hidden ones) where additional screws might be.

Internal expansion cards plug into slots on the motherboard, as shown in Figure 8.6. Note that because of size and placement differences, it's impossible to insert the wrong type of card into a slot—for instance, a PCI card won't fit in an ISA slot. (If you run out of one type, you may be able to find a device in the slot type that's available to you, or you may have to remove one card to make room for another. Sometimes you can resort to using another type of device, like a USB-to-Ethernet adapter rather than an incomputer Ethernet card.) To insert a card, you must power off the computer. Failing to do so is virtually certain to result in damage to the card or the computer. After the power is off, align the card so that its connector matches that of the slot, and apply some force to push it into the expansion slot. You should then use a screw to secure the top of the card to the computer's case. Some components, like RAM and even the CPU, are installed in slots or sockets similar to those used by expansion cards. Their installation procedures are similar, but these devices don't attach in a way that makes them accessible from outside the computer.

FIGURE 8.6 Expansion slots come in several different and incompatible varieties.

FIGURE 8.6 Expansion slots come in several different and incompatible varieties.

You've probably had the experience of walking across a carpeted room and receiving an electrostatic shock when you touch a door knob. This phenomenon is known as an electrostatic discharge (ESD). The same thing can happen when you work on computer hardware, but such an event can actually damage the computer or component. For this reason, it's important that you ground yourself when working on computer hardware—either a complete computer or individual components. The best way to do this is with an ESD wrist strap. This is a strap that resembles a bracelet or hospital ID tag, but it connects to a wall electrical outlet's ground prong. The result is that your body is electrically grounded, so any static you might build up is discharged, literally into the ground, before it can do any harm to a computer. If you lack an ESD strap, you should at least not move around on carpet wearing rubber-soled shoes when working on a computer (such movement is likely to build up electrostatic charges), and you should frequently ground yourself in other ways, such as by touching a radiator or water tap. If you fail to take such actions, you may destroy a computer or a component just by touching it, particularly if you're working in a dry environment.

Protecting the computer is important, but still more important is protecting yourself. You'll be safest if you unplug a computer from the wall before working on it. Modern computers don't shut off all power when they're turned off, so even if you've shut down a system, it will still have a few live circuits, which might give you a jolt if you accidentally touch one. A few computers have toggle switches on their backs that can cut all power, and using such a switch can have nearly the same safety effect as unplugging the computer. (When switched off but plugged in, a computer with such a switch is also a useful ground source—you can ground yourself by touching the power supply rather than a radiator or water tap.)

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The Ultimate Computer Repair Guide

The Ultimate Computer Repair Guide

Read how to maintain and repair any desktop and laptop computer. This Ebook has articles with photos and videos that show detailed step by step pc repair and maintenance procedures. There are many links to online videos that explain how you can build, maintain, speed up, clean, and repair your computer yourself. Put the money that you were going to pay the PC Tech in your own pocket.

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