PC Repair Troubleshooting Course Manual

PC Repair Troubleshooting Course Manual

(Parte 1 de 4)

A typical PC contains the following hardware:

Case Power Supply Motherboard CPU Memory Hard Disk Floppy Disk CD-ROM Video Adapter Sound Card Modem Mouse Keyboard Monitor .

There are many other possible hardware components, such as a DVD, CD-RW, Zip drive or network card. There are also many subcomponents of a PC, such as the cooling fan, printer port or reset switch to name a few. This article focuses on the basic PC hardware. The hardware in the list above is nearly universal to a basic PC.

While a PC is built up from hardware components, the hardware is only half of the equation. The other vital part of a PC is the software. Without software, the hardware is useless; and vice versa.

The fundamental software for a PC is called an "operating system". Without an operating system or "OS", a PC can't do much. The operating system tells the components of a PC what to do and when to do it. Windows, MAC OS, Linux and Unix are all examples of operating systems.

C H A P T E R1111
++ + +

In This Chapter

Who Should Read this Book

How this Book is Organized

Of Special Note for the eBook

Conventions Used in this Book

The Parts of a Personal Computer The Case

The case is the box that houses the PC. All of the hardware, except for the peripherals, is housed inside the case. There are two common styles of cases: "desktop" and "tower." The desktop case usually sits under the monitor and is roughly the size of two or three shoe boxes side by side. The tower case stands upright on one end and is usually placed on the floor. Tower cases can be the same size as a desktop case but often range up much larger. Another, less common, case style is the "rack mount" case which slides in and out of an equipment rack.

The Power Supply

Where the power cord connects to the back of the PC is the power supply. The power supply converts AC current from the wall outlet to the appropriate DC voltages for the various components of the computer.

The power supply has a fan built into it to keep itself and the PC cool. Most PC's have at least one additional cooling fan, often mounted directly on the CPU. The power supply or its internal fan can wear out. Fortunately, the entire unit is easily replaced.

The Motherboard

The motherboard is the largest and most fundamental component of a PC. Every other hardware component is somehow attached to the motherboard. The motherboard is the common link for every component to communicate and work together.

The motherboard has a series of slots, sockets and connectors for connecting the various components of a PC. The memory, accessory cards, and CPU are installed directly onto the motherboard in most cases. The drives and peripherals communicate with the motherboard through wired connections.

It is becoming increasingly common for motherboards to integrate features that used to require separate accessory cards. Most motherboards integrate drive controllers and communication ports; and with greater frequency they integrate sound, video and network features as well.

There are a wide range of motherboards to choose from. They differ in features, speed, capacity and the CPU supported. They also differ in size, shape and layout, this is commonly referred to as the "form factor".


The CPU, which stands for Central Processing Unit, is the brain of the PC. It is often referred to as the "processor" or "chip". The CPU directs, coordinates and communicates with the hardware components and performs all of the "thinking". What a CPU actually does is perform mathematical calculations. It is the software that people write that translates those calculations into useful functions for us.

The speed of the CPU, generally speaking, is the number of calculations it can perform in one second. It is more complicated than that, but it is a reasonable way to think of the speed. A 500 MHz (megahertz) CPU performs about 500,0,0 mathematical calculations per second.

As the speed of new CPUs increase, the difference is becoming less obvious to computer users. A CPU that is twice as fast as another one will not result in a PC running twice as fast. The CPU has to wait for other, slower components and for the user too. The CPU spends a lot of time sitting idle, waiting for something to do.

CPUs have something called a "cache" or memory cache. The memory cache is where information is stored that the CPU is likely to need soon. This memory is in addition to the normal memory installed in a PC. The difference is that the cache is built right onto the CPU (and/or very near the CPU), and it is much faster than conventional memory. Cache memory was developed to reduce the time the CPU had to wait while information was retrieved from the standard memory.

The RAM Memory

The memory chips store information, temporarily, for short term use. A PC's memory is an entirely different thing from the hard disk "memory". The hard disk stores information "permanently" for long term use.

A PC's memory only contains information when the PC is on. When the PC is turned off, the information in the memory chips disappears. The information in memory is similar to a thought, it gets replaced when you start thinking about something else. Hard disk memory is like writing down the information and storing it in a filing cabinet.

The Hard Disk Drive

A hard disk (also called a "hard drive") is much like a filing cabinet. The programs and data are stored on the hard disk and the computer accesses them as needed. When the computer accesses the hard drive, it is reading the stored information into memory. That memory is the temporary workspace. The original file on the hard disk is left undisturbed. When the computer stores information, it writes the data to the hard disk. That process results in the old file being replaced or modified with the new information. If you save data to a new file, or install new software, the information is written to the disk in an available, unused portion of the disk.

The Floppy Disk Drive

The floppy disk drive is a device that records data onto a removable storage disk called a floppy disk. Floppy disks, also called "floppies", are the most basic storage medium for data. However their limited capacity, typically 1.4 megabytes, makes them of limited use.

A floppy disk can be used to copy files from one PC to another PC or for making backup copies of files. Replacing a floppy drive is very easy and inexpensive to do, should the need arise.


The CD-ROM drive is a device that reads information or music off of a compact disk (CD). CD-ROM stands for Compact Disc Read Only Memory. Most software is distributed on CDs because of their low cost and large capacity (650MB or more).

The CD is spun at high speed inside the drive while a laser is directed at the surface to read the data or music. The CDROM speed is referenced as 12X or 12 speed (or any other number). This simply means that it spins the CD that many times faster than the original industry specification. So, a 48X CD-ROM spins the CD up to 48 times faster than the original specification. Faster is better.

Many PCs are now built with a CD-RW drive, which stands for Compact Disc, Read-Write. Unlike a standard CDROM, you can write data onto a CD with a CD-RW drive. CD-R disks allow you to write to the CD once and read it an unlimited number of times. With the use of RE-writable CDs (CD-RWs) you can reuse the disk and rewrite over it again many times.

The speeds of a CD-RW are expressed like this, 4X 4X 32X. This means it can write to the CD up to 4 times the spec speed, rewrite the CD up to 4 times spec speed and read the CD up to 32 times the spec speed.

The Graphics Card or Video Card

The video adapter card or graphics adapter translates information into graphics and text that appear on the monitor screen.

The graphics adapter plugs into a slot on the motherboard or is incorporated directly into the electronics of the motherboard. Most motherboards now include a slot specifically designed for the graphics adapter called the AGP slot (Advanced Graphics Port).

Modern graphics adapters usually incorporate some memory right on the card to improve their performance. To further improve the performance of the video output, a second graphics accelerator card can be used in tandem with the graphics adapter.

The Sound Card

Most PCs are typically equipped for multimedia. They can play sounds, music, and speech. The sound card processes the information and outputs the signal to the speakers.

The sound card plugs into a slot on the motherboard or is incorporated directly into the the motherboard. With a basic sound card a microphone, speakers, joystick and an auxiliary sound source can be connected to it. More advanced cards may offer additional input and output features.

The Modem

The modem is a device that enables the PC to use a telephone line to communicate with other PCs and devices. The name comes from "MOdulation DEModulation".

The modem plugs into a slot on the motherboard or is incorporated directly into the electronics of the motherboard. It converts data into signals that can be transmitted over the telephone line and receives data to convert back for the PC to use.

The Mouse

The mouse is a user input device that enables you to communicate with your PC. By moving the mouse and pressing the two or three buttons, you can highlight and select images on the screen to give directions to your PC. Some mice offer a wheel to aid in the scrolling of a window without having to move the mouse.

A mouse is usually connected by a wire but wireless mice are also available. Wired mice may use a serial, PS/2 or a USB port. Other variations of mice available include the trackball and touchpad.

The mouse detects movement either as a ball underneath the mouse rolls along your desk

The Keyboard

The keyboard is the primary user input device. It enables you to communicate with your computer. While the mouse is also a fundamental device to control the PC, the keyboard goes one step further by allowing you to enter specific information as opposed to simply pointing and clicking.

The keyboard connects to the computer through a wire, although wireless keyboards are also available. Variations of the classic keyboard include the addition of action specific buttons, most commonly for Internet features, and split keyboards which angle the two halves of the keyboard to reduce stress on your wrists as you type.

The Monitor

Monitors obviously display what is going on in your computer. They can run at various resolutions and refresh rates. 640x480 is the default resolution for the Windows operating systems (this is a low resolution where objects appear large and blocky). 640x480 just means that 640 pixels are fit across the top of your monitor and 480 up and down. Most users prefer higher resolutions such as 800x600 or 1024x768 all the way up to 1600x1200 (and higher for graphics professionals). The higher resolutions make objects smaller, but clearer (because more pixels are fit in the screen). You can fit more objects on a screen when it is in a higher resolution. Larger monitors are better for running at the higher resolutions. If you run a high resolution on a small monitor, the text may be hard to read because of its small size, despite the clarity.

smoother your picture will be and the less "flicker" you will see

The refresh rate is how fast the monitor can refresh (redraw) the images on the screen. The faster it can do this, the

your monitor is dim and blurry, the picture will come out the same way

The monitor has a lot to do with the quality of the picture produced by your video card, but it doesn't actual "produce" the graphics - the video card does all this processing. But, if your video card is producing a bright detailed picture and C H A P T E R 2

OUTCOME: Students will map out and disassemble the PC. Through a hands on approach students become familiar with the components and the architecture of the PC. Their map of the PC will be used in the reassembly of the PC. Through this activity students will become familiar with the organization of the digital computer system.

MATERIALS: Paper, pencil, Paper cup, toolkit, clear table (to lay out all the components), operating PC, have already documented BIOS, CMOS.

*Teacher will give a demo sheet. (see worksheet attached) * Teacher will instruct the students On the purposes of this lesson

* Each student will work in groups of two or three (max three)

*Students will be given appox. Three to four periods to complete this task.

*Teacher must check the students map of the computer before they

Are to proceed.

*Students will add notes to their Personal journal.

*Students will take off the computer cover and draw a detailed map as to how the computer is put together. All the components must be described and sketched before the students can proceed.

*Once the teacher has graded your map then slowly disassemble the PC in the order specified on the worksheet?

*Now using your map lay the parts out on the table in an organized fashion as to how the computer fits together.

*Follow the instructions on the worksheet labeled "ASSEMBLY".

*Final operation check by your teacher.

Disassembling the Computer It’s Not A Race

If you are familiar with the procedure of disassembling a computer, then you can skip this section. If you are a beginner and actually want to learn something, then document well, and learn or re-affirm your knowledge about everything you see inside. Given a screwdriver, a 10-year old could probably have the computer apart in a half-hour or so. If you're using this section as a lab or learning assignment, and you have your computer apart in the same time as a 10-year old, then that's the level you'l be at. But if you take a slow relaxed approach, discuss, question and research each component as it's removed, you'l learn alot. Read the sections on What's Inside and What You See, fal back on your own knowledge, use the Internet, your books and resource material. It's impossible to retain all the information, so one of the most important computer skills you can learn is how to research and use your resources to find what you need. Here's an example of some questions to think about or discuss as you proceed:

Should I document everything I do or everything I remove?

Am I taking the best ESD precautions available to me right now. When you remove an expansion card what kind of card is it? What kind of expansion slot did it come from? How many bits wide is that slot? What is the bus speed? What does the card do? If there's any wires attached to the card, what's the other end attached to and what are the wires or cables for. What kind of port is on the end of the card? When removing a drive, what kind of drive is it? Is there information documented right on the drive itself? What kind of power connector does it use? Are there jumper settings on the drive? What for? Are any drives connected together or do they all have their own cable? Does it matter which cable I hook up when I reassemble? What are some of the things I know about this particular type of drive? When removing wires or cables, what are the cables for? Which connectors are actually being used and what could the other ones be for? Are they following the pin-1 rule? Is pin-1 actually designated on the device the cable is attached to? Is it designated in more than one way? Am I still taking proper ESD precautions and is my antistatic strap still hooked up? Look at the motherboard again when there's not so much in the way. Can you point out the CPU? How about the BIOS chip, the battery, cache RAM, keyboard connector? Is it an AT, Baby AT, or ATX format? Is there a math coprocessor? Where is it? Is the system memory supplied on SIMMs or DIMMs? How many pins on the memory module? How many memory slots are thee for each bank of system memory? Is the CPU installed in a ZIF socket or a friction socket? Are there any jumpers on the motherboard? Is there any information silkscreened on the board itself?

(Parte 1 de 4)