Domain 2 Diagnosing and Troubleshooting

CompTIA A+ Exam Objectives Covered in This Chapter

  • 2.1 Recognize common problems associated with each module and their symptoms, and identify steps to isolate and troubleshoot the problems. Given a problem situation, interpret the symptoms and infer the most likely cause.
  • 2.2 Identify basic troubleshooting procedures and tools, and how to elicit problem symptoms from customers. Justify asking particular questions in a given scenario.

When you’re troubleshooting hardware, there are a few common problems that any experienced technician should know about. These common issues usually have simple solutions. Knowing these problems and their solutions will make you a more efficient troubleshooter.

Recognizing, Isolating, and Troubleshooting Common Problems

Most computer technicians spend a great deal of time troubleshooting and repairing systems, and Domain 2.1 of the exam tests your knowledge of basic troubleshooting procedures. To study for it, you’ll need to familiarize yourself with common problems and solutions related to motherboards, hard disks, RAM, cooling, and the other major system components.

Critical Information

Your value as a technician increases as you gain experience, because of the reduced time it takes you to accomplish common repairs. Your ability to troubleshoot by past experiences and gut feelings will make you more efficient and more valuable, which in turn will allow you to advance and earn a better income. This chapter will give you some guidelines you can use to evaluate common hardware issues that you are sure to face.

POST Routines

Every computer has a diagnostic program built into its BIOS called the power on self-test (POST). When you turn on the computer, it executes this set of diagnostics. Many steps are involved the POST, but they happen very quickly, they are invisible to the user, and they vary among BIOS versions. The steps include checking the CPU, checking the RAM, checking for the presence of a video card, and so on. The main reason to be aware of the POST’s existence is that if it encounters a problem, the boot process stops. Being able to determine at what point the problem occurred can help you troubleshoot.

One way to determine the source of a problem is to listen for a beep code. This is a series of beeps from the computer’s speaker. The number, duration, and pattern of the beeps can sometimes tell you what component is causing the problem. However, the beeps differ depending on the BIOS manufacturer and version, so you must look up the beep code in a chart for your particular BIOS. Different BIOS manufacturers use the beeping differently. AMI BIOS, for example, relies on a raw number of beeps, but uses patterns of short and long beeps.

Another way to determine a problem during the POST routine is to use a POST card. This is a circuit board that fits into an ISA or PCI expansion slot in the motherboard and reports numeric codes as the boot process progresses. Each of those codes corresponds to a particular component being checked. If the POST card stops at a certain number, you can look up that number in the manual that came with the card to determine the problem.


BIOS Central is a website containing charts detailing the beep codes and POST error codes for many different BIOS manufacturers:

Motherboard and CPU Problems

Most motherboard and CPU problems manifest themselves by the system appearing completely dead. However, “completely dead” can be a symptom of a wide variety of problems, not only with the CPU or motherboard but also with the RAM or the power supply. So, a POST card (described in the preceding section) may be helpful in narrowing down the exact component that is faulty.

When a motherboard fails, it is usually because it has been damaged. Most technicians cannot repair motherboard damage; the motherboard must be replaced. Motherboards can become damaged due to physical trauma, exposure to electrostatic discharge (ESD), or short-circuiting. To minimize the risk of these damages, observe the following rules:

  • Handle a motherboard as little as possible, and keep it in an antistatic bag whenever it is removed from the PC case.
  • Keep all liquids well away from the motherboard, because water can cause a short circuit.
  • Wear an antistatic wrist strap when handling or touching a motherboard.
  • When installing a motherboard in a case, make sure you use brass stand-offs with paper washers to prevent any stray solder around the screw holes from causing a short circuit with the metal of the screw.

A CPU may fail because of physical trauma or short-circuiting, but the most common cause for a CPU not to work is failure to install it properly. With a PGA-style CPU, ensure that the CPU is oriented correctly in the socket. With an SECC-style CPU, make sure the CPU is completely inserted into its slot.

I/O Ports and Cables

I/O ports include legacy parallel and serial, USB, and FireWire ports, all of which are used to connect external peripherals to the motherboard. When a port does not appear to be functioning, check the following:

  • Cables are snugly connected.
  • The port has not been disabled in BIOS Setup.
  • The port has not been disabled in Device Manager in Windows.
  • No pins are broken or bent on the male end of the port or cable being plugged into it.

If you suspect that the cable, rather than the port, may be the problem, swap out the cable with a known-good one. If you do not have an extra cable, you can test the existing cable with a multimeter by setting it to ohms and checking the resistance between one end of the cable and the other.

Use a pin-out diagram, if available, to determine which pin matches up to which at the other end. There is often—but not always—an inverse relationship between the ends. In other words, at one end pin 1 is at the left, and at the other end it is at the right on the same row of pins.

Cooling Issues

A PC that works for a few minutes and then locks up is probably experiencing overheating due to a heat sink or fan not functioning properly. To troubleshoot overheating, first check all fans inside the PC to ensure they are operating, and make sure that any heat sinks are firmly attached to their chips.

In a properly designed, properly assembled PC case, air flows in a specific path from the power supply fan through the vent holes. Cases are designed to cool by making the air flow in a certain way. Therefore, operating a PC with the cover removed can actually make a PC more susceptible to overheating, even though it is “getting more air.”

Similarly, operating a PC with empty expansion slot backplates removed can inhibit a PC’s ability to cool itself properly because the extra holes change the airflow pattern from what was intended by its design.

Although CPUs are the most common component to overheat, occasionally chips on other devices, particularly video cards, may also overheat. Extra heat sinks or fans may be installed to cool these chips.

Case Issues

A PC case holds the drives in its bays, holds the power supply, and has lights and buttons on the front. For the first two of those functions, simply make sure that the drives and the power supply are tightly fastened in the case with screws.

If one of the lights or buttons on the front of the PC is not functioning, remove the cover and check the wires that run from the back of that button/light to the motherboard. If the wire has become detached, reattach it. Refer to the motherboard manual or the writing on the motherboard itself to determine what goes where.

Hard Disk System Problems

Hard disk system problems usually stem from one of three causes:

  • The adapter (that is, the IDE or SCSI interface) is bad.
  • The disk is bad.
  • The adapter and disk are connected incorrectly.

The first and last causes are easy to identify, because in either case the symptom will be obvious: The drive won’t work. You simply won’t be able to get the computer to communicate with the disk drive.

However, if the problem is a bad disk drive, the symptoms aren’t as obvious. As long as the BIOS POST routines can communicate with the disk drive, they are usually satisfied. But the POST routines may not uncover problems related to storing information. Even with healthy POST results, you may find that you’re permitted to save information to a bad disk, but when you try to read it back you get errors. Or the computer may not boot as quickly as it used to, because the disk drive can’t read the boot information successfully every time.

In some cases, reformatting the drive can solve the problems described in the preceding paragraph. In other cases, reformatting brings the drive back to life only for a short while. The bottom line is that read and write problems usually indicate that the drive is malfunctioning and should be replaced soon.


Never low-level format IDE or SCSI drives! They are low-level formatted from the factory, and you may cause problems by using low-level utilities on these types of drives.

Modem Problems

The most common peripheral problems are those related to modem communications. The symptoms of these problems include the following:

  • The modem won’t dial.
  • The modem keeps hanging up in the middle of the communications session.
  • The modem spits out strange characters to the terminal screen.

If the modem won’t dial, first check that it has been configured correctly in Windows, including its resource assignments.

Some modems work only under Windows because some of their functions rely on Windows software; these are called Winmodems or software modems. If such a modem does not work immediately upon installation, try running the Setup software that came with the modem.

If the configuration is correct, and Windows recognizes the modem, it should work for dial-up networking connections.

AT Commands

When you’re using a terminal application such as HyperTerminal, it is important to use the correct initialization commands. These are the commands sent to the modem by the communications program to initialize it. These commands tell the modem such things as how many rings to wait before answering, how long to wait after the last keystroke was detected for it to disconnect, and at what speed to communicate.

Modem initialization commands are known as the Hayes command set or the AT command set, because each Hayes modem command started with the letters AT (presumably calling the modem to ATtention).

Each AT command does something different. The letters AT by themselves ask the modem if it’s ready to receive commands. If it returns OK, the modem is ready to communicate. If you receive Error, there is an internal modem problem that may need to be resolved before communication can take place.

Table 2.1 lists a few of the most common AT commands, their functions, and the problems they can solve. You can send these commands to the modem by opening a terminal program like Windows Terminal or HyperTerminal and typing them in. All commands should return OK if they were successful.

Table 2.1: Common AT Commands





Tells the modem that what follows the letters AT is a command that should be interpreted

Used to precede most commands.

ATDT nnnnnnn

Dials the number nnnnnnn as a tone-dialed number

Used to dial the number of another modem if the phone line is set up for tone dialing.

ATDP nnnnnnn

Dials the number nnnnnnn as a pulse-dialed number

Used to dial the number of another modem if the phone line is set up for rotary dialing.


Answers an incoming call manually

Places the line off-hook and starts to negotiate communication with the modem on the other end.

ATH0 (or +++ and then ATH0)

Tells the modem to hang up immediately

Places the line on-hook and stops communication. (Note: The 0 in this command is a zero, not the letter O.)


Resets the modem to factory default settings

This setting works as the initialization string when others don’t. If you have problems with modems hanging up in the middle of a session or failing to establish connections, use this string by itself to initialize the modem.


Resets the modem to power-up defaults

Almost as good as AT&F, but may not work if power-up defaults have been changed with S-registers.


Waits n rings before answering a call

Sets the default number of rings that the modem will detect before taking the modem off-hook and negotiating a connection. (Note: The 0 in this command is a zero, not the letter O.)


Waits n seconds for a dial tone before dialing

If the phone line is slow to give a dial tone, you may have to set this register to a number higher than 2.


Pauses briefly

When placed in a string of AT commands, the comma will cause a pause to occur. Used to separate the number for an outside line (many businesses use 9 to connect to an outside line) and the real phone number (for example, 9,555-1234).

*70 or 1170

Turns off call waiting

The click you hear when you have call waiting (a feature offered by the phone company) will interrupt modem communication and cause the connection to be lost. To disable call waiting for a modem call, place these commands in the dialing string like so: *70,555-1234. Call waiting will resume after the call is hung up.


Displays when a successful connection has been made

You may have to wait some time before this message is displayed. If this message is not displayed, the modem couldn’t negotiate a connection with the modem on the other end of the line, possibly due to line noise.


Displays when the number dialed is busy

If this message is displayed, some programs will wait a certain amount of time and try again to dial.


Displays when the modem has detected a ringing line

When someone is calling your modem, the modem will display this message in the communications program. You type ATA to answer the call.

If two computers can connect, but they both receive garbage on their screens, there’s a good chance that the computers don’t agree on the communications settings. Settings such as data bits, parity, stop bits, and compression must all agree in order for communication to take place.

Keyboard and Mouse Problems

Usually, keyboard problems are environmental. Keyboards get dirty, and the keys start to stick.


If a keyboard is actually malfunctioning (for example, sending the wrong characters to the display), it is most cost effective to replace it rather than spend hours attempting to fix it, because keyboards are fairly inexpensive.

One way to clean a keyboard is with the keyboard cleaner sold by electronics supply stores. This cleaner foams up quickly and doesn’t leave a residue behind. Spray it liberally on the keyboard and keys. Work the cleaner in between the keys with a stiff toothbrush. Blow away the excess with a strong blast of compressed air. Repeat until the keyboard functions properly. If you have to clean a keyboard that’s had a soft drink spilled on it, remove the key caps before you perform the cleaning procedure; doing so makes it easier to reach the sticky plungers.


Remember that most of the dollars spent on systems are for labor. If you spend an hour cleaning a $12.00 keyboard, then you have probably just cost your company $20.00. Knowing how to fix certain things doesn’t necessarily mean that you should fix them. Always evaluate your workload, the cost of replacement, and the estimated cost of the repair before deciding on a course of action.

Similarly, most mouse problems, such as the pointer failing to move in one direction or the other, or the pointer jumping around onscreen, are due to dirt building up inside the mouse. To clean a standard mouse, remove the plate on the bottom of the mouse that holds the ball in place; then remove the ball and clean the inside chamber with an alcohol-dipped cotton swab. Clean the ball itself with mild soap and water. Do not use alcohol on the ball, because it tends to dry out the rubber.

Display System Problems

There are two types of video problems: no video and bad video. No video means no image appears on the screen when the computer is powered up. Bad video means the quality is substandard for the type of display system being used.

No Video

Any number of things can cause a blank screen. The first three are the most common: the power is off, the monitor’s cable is unplugged, or the contrast or brightness is turned down.

If you’ve checked the power as well as the brightness and contrast settings, then the problem could be a bad video card or a bad monitor. Most monitors these days display a Working message briefly when you turn them on, so you can ascertain that the monitor is working and that an amber light appears on the front. When the PC starts up, the light on the front of the monitor changes from amber to green, indicating that the monitor is receiving a signal.

If the monitor is working but not receiving a signal from the PC, the video card may be bad. However, no video can also mean a problem with the motherboard, RAM, or CPU, so it is not a given that the video card is at fault when no video appears.

Malfunctioning monitors are usually not worth fixing, because the cost of the labor involved exceeds the cost of a brand-new monitor. In addition, it may be difficult to find a technician to work on a monitor, because it is not part of most standard PC technician training programs (due to the risk of electric shock from the high-voltage capacitor inside the monitor).

Bad Video

A monitor that does not display one of the three basic colors (red, green, or blue) probably has a bad cable, a bent or broken pin, or a loose connection at either the PC or the monitor. This is the case because different pins on the connectors—and wires in the cable—control different colors.

Color problems may also result from the monitor being out of adjustment. With most new monitors, this is an easy problem to fix. Old monitors had to be partially disassembled to change these settings. New monitors have push-button control panels for changing these settings.

Exposure to a magnetic field can cause swirls and fuzziness even in high-quality monitors. The Earth itself generates magnetic fields, as do unshielded speakers and power surges. Most monitors have metal shields that can protect against magnetic fields. But eventually these shields can get polluted by taking on the same magnetic field as the Earth, so they becomes useless. To solve this problem, these monitors have a built-in feature known as Degauss. This feature removes the effects of the magnetic field by creating a stronger magnetic field with opposite polarity that gradually fades to a field of zero. A special Degauss button or feature in the monitor’s on-screen software activates it. You need only press it when the picture starts to deteriorate. The image will shake momentarily during the Degauss cycle, and then return to normal.


If you have a monitor that shows bad distortion, and changing the settings or Degaussing has no effect, then look for magnetic interference caused by nearby florescent lights or large power sources.

Floppy and Other Removable Disk Drive Problems

Most floppy-drive problems result from bad media. Your first troubleshooting technique with floppy-drive issues should be to try a new disk.

One of the most common problems that develops with floppy drives is misaligned read/write heads. The symptoms are fairly easy to recognize—you can read and write to a floppy on one machine but not on any others. This is normally caused by the mechanical arm in the floppy drive becoming misaligned. When the disk was formatted, it was not properly positioned on the drive, thus preventing other floppy drives from reading it.

Numerous commercial tools are available to realign floppy drive read/write heads. They use a floppy drive that has been preformatted to reposition the mechanical arm. In most cases, though, this fix is temporary—the arm will move out of place again fairly soon. Given the inexpensive nature of the problem, the best solution is to spent a few dollars and replace the drive.

Another problem you may encounter is a phantom directory listing. For example, suppose you display the contents of a floppy disk, and then you swap to another floppy disk but the listing stays the same. This is almost always a result of a faulty ribbon cable; a particular wire in the ribbon cable signals when a disk swap has taken place, and when that wire breaks, this error occurs.

Sound Card Problems

Sound cards are traditionally one of the most problem-ridden components in a PC. They demand a lot of PC resources and are notorious for being very inflexible in their configuration. The most common problems related to sound cards involve resource conflicts (IRQ, DMA, or I/O address). The problem is much less pronounced on PCI than on ISA cards.

Luckily, most sound-card vendors are quite aware of the problems and ship very good diagnostic utilities to help resolve them. Use your PC troubleshooting skills to determine the conflict, and then reconfigure until you find an acceptable set of resources that are not in use.

Some sound cards are not completely Plug-and-Play compatible. Windows might detect that new hardware has been installed, but be unable to identify the new hardware as a working sound card. To fix this problem, run the Setup software that came with the sound card.


CD-ROM and DVD problems are normally media related. Although compact disc technology is much more reliable than floppy disks, it is still not perfect. Another factor to consider is the cleanliness of the disc. On many occasions, if a disc is unreadable, simply cleaning it with an approved cleaner and a lint-free cleaning towel will fix the problem.

If the operating system does not see the drive, start troubleshooting by determining whether the drive is receiving power. If the tray will eject, you can assume there is power to it. Next, check BIOS Setup (for IDE drives) to make sure the drive has been detected. If not, check the Master/Slave jumper on the drive and make sure that the IDE adapter is set to Auto, CD-ROM, or ATAPI in BIOS Setup.

In order to play movies, a DVD drive must have MPEG decoding capability. This is usually accomplished via an expansion board, but it may be built into the video card or sound card, or it may be a software decoder. If DVD data discs will play but not movies, suspect a problem with the MPEG decoding.

If a CD-RW or DVD drive works normally as a regular CD-ROM drive but does not perform its special capability (does not read DVD discs, or does not write to blank CDs), perhaps software needs to be installed to work with it. For example, with CD-RW drives, unless you are using an operating system such as Windows XP that supports CD writing, you must install CD writing software in order to write to CDs.

Network Interface Card

In general, network interface cards (NICs) are added to a PC via an expansion slot. The most common issue that prevents network connectivity is a bad or unplugged patch cable.

Cleaning crews and the rollers on the bottoms of chairs are the most common threats to a patch cable. In most cases, wall jacks are placed 4 to 10 feet away from the desktop. The patch cables are normally lying exposed under the user’s desk, and from time to time damage is done to the cable or it is inadvertently snagged and unplugged. When you troubleshoot a network adapter, start with the most rudimentary explanations first. Make sure the patch cable is tightly plugged in, and then look at the card and see if any lights are on. If there are lights on, use the NIC’s documentation to help troubleshoot. More often than not, simply shutting down the machine, unplugging the patch and power cables for a moment, and then reattaching them and rebooting the PC will fix an unresponsive NIC.


Although this is not on the test, it’s useful information: Wake On LAN cards have more problems than standard network cards. In my opinion, this is because they are always on. In some cases, you will be unable to get the card working again unless you unplug the PC’s power supply and reset the card.

BIOS Issues

Computer BIOSes don’t really go bad; they just become out-of-date. This is not necessary a critical issue—they will continue to support the hardware that came with the box. It does, however, become an issue when the BIOS doesn’t support some component that you would like to install—a larger hard drive, for instance.

Most of today’s BIOSes are written to an EEPROM and can be updated through the use of software. Each manufacturer has its own method for accomplishing this. Check out the documentation for complete details.


If you make a mistake in the upgrade process, the computer can become unbootable. If this happens, your only option may be to ship the box to a manufacturer-approved service center. Be careful!

Power Supply Problems

Power supply problems are usually easy to troubleshoot. The system does not respond in any way when the power is turned on. When this happens, open the case, remove the power supply, and replace it with a new one.

Be aware that different cases have different types of on/off switches. The process of replacing a power supply is a lot easier if you purchase a replacement with the same mechanism. Even so, remember to document exactly how the power supply was connected to the on/off switch before you remove it.

Problems with Notebook PCs

Notebook PCs have many of the same problems and solutions as desktop PCs. Most of their unique problems have to do with power.

When a battery does not hold a charge well, it is probably a Nickel Cadmium (NiCad) battery. This type of battery has a memory, so if it is not fully discharged before recharging, it fails to hold as much of a charge the next time. The solution is to replace it with a different type of battery, such as Lithium Ion, or to replace it with the same type of battery and then be careful to let it discharge each time.

When a notebook computer will not enter Standby or Hibernate mode, or will not wake up from it, suspect a conflict between the BIOS’s power management and Windows’. Disable one or the other to prevent the conflict.

An older BIOS may support the older Advanced Power Management (APM) standard rather than the newer Advanced Configuration and Power Interface (ACPI) power management. Updating the BIOS may provide the support needed for ACPI, which is more trouble-free.

In the short term, to wake up a PC that is stuck in Hibernate or Standby, try pressing and holding the Power button for 5 to 10 seconds. If this does not work, try unplugging the PC from the AC outlet and removing the batteries. Then replace the battery and turn it back on.

Sometimes an outdated video driver can cause power-management problems; updating the video driver may solve the problem.

Miscellaneous Problems

Some common problems do not fit well into categories. This section lists some common hardware issues you will be faced with.

Dislodged Chips and Cards

The inside of a computer is a harsh environment. The temperature inside the case of some Pentium computers is well over 100 F! When you turn on your computer, it heats up. Turn it off, and it cools down. After several hundred such cycles, some components can’t handle the stress and begin to move out of their sockets. This phenomenon is known as chip creep, and it can be really frustrating.

Chip creep can affect any socketed device, including ICs, RAM chips, and expansion cards. The solution to chip creep is simple: Open the case and reseat the devices. It’s surprising how often this is the solution to phantom problems of all sorts.

Another important item worth mentioning is an unresponsive but freshly unboxed PC. With the introduction of the Type II and Type II-style of processors, the number of dead boxes increased dramatically. In fact, at that time I was leading a 2,000-unit migration for a large financial institution. As with any large migration, time and manpower were in short supply. The average dead PC ratio was about 1 out of every 20. When about 10 DOAs had stacked up, I stayed after work one night to assess the problem. After checking the power supply, RAM, and cables on these integrated systems, an examination of the chip provided me with the fix. These large, top-heavy processors can become dislodged during shipment. Shortly after, manufacturers began using a heavier attachment point for the slot style of processor, which has helped tremendously.

Environmental Problems

Computers are like human beings. They have similar tolerances to heat and cold. In general, anything comfortable to us is comfortable to computers. They need lots of clean, moving air to keep them functioning.

Dirt, grime, paint, smoke, and other airborne particles can become caked on the inside of the components. This is most common in automotive and manufacturing environments. The contaminants create a film that coats the components, causing them to overheat and/or conduct electricity on their surface. Simply blowing out these exposed systems with a can of condensed air from time to time can prevent damage to the components. While you are cleaning the components, be sure to clean any cooling fans in the power supply or on the heat sink.


To clean the power supply fan, blow the air from the inside of the case. When you do this, the fan will blow the contaminants out the cooling vents. If you spray from the vents toward the inside of the box, you will be blowing the dust and grime inside the case or back into the fan motor.

One way to ensure that the environment has the least possible effect on your computer is to always leave the blanks in the empty slots on the back of your box. These pieces of metal are designed to keep dirt, dust, and other foreign matter from the inside of the computer. They also maintain proper airflow within the case to ensure that the computer does not overheat.

Exam Essentials

Be familiar with the purpose of POST routines.The POST routines perform entry-level hardware troubleshooting as a PC starts. Be familiar with the abilities of the POST and its use.

Be able to diagnose port problems.When a port is not functioning, make sure you know the steps to take to ensure that it is physically connected, enabled in BIOS, and recognized in Windows.

Know how to troubleshoot hard-disk system problems.Be aware of the common causes of hard-disk problems, including improper jumper configuration, BIOS Setup, and formatting/partitioning issues.

Identify problems that can result from overheating.Overheating can cause spontaneous rebooting or shutdown, and is often caused by nonfunctioning cooling fans or improper airflow through the PC.

Be able to determine display system problems.The most common display problems relate to power, brightness, or contrast. Simply adjusting the monitor controls should be your first step when troubleshooting.

Recognize the symptoms of floppy-drive problems.Most floppy-drive problems result from bad media. Your first troubleshooting technique with floppy-drive issues should be to try a new disk.

Know how to troubleshoot sound-card problems.Sound cards demand a lot of PC resources and are notorious for being very inflexible in their configuration. The most common problems related to sound cards involve resource conflicts (IRQ, DMA, or I/O address).

Learn to identify BIOS issues.BIOS issues are related to the inability to support hardware. In most cases, a program or flash upgrade is available to update the BIOS so that components can be supported.

Recognize power supply problems.Become familiar with the symptoms of a dead, failing, or overloaded power supply.

Know the symptoms of dislodged chips and cards.Dislodged components are the most common issues you will face. Become familiar with the symptoms and their fixes.

Basic Troubleshooting Procedures and Tools

Just as all artists have their own style, all technicians have their own way to troubleshoot. Some people use their instincts; others rely on advice from other people. The most common troubleshooting tips can be condensed into a step-by-step process. You try each step, in order. If the first step doesn’t narrow down the problem, you move on to the next step.

Critical Information

In this section we’ll look at each step in the troubleshooting process.

Step 1: Define the Problem

If you can’t define the problem, you can’t begin to solve it. You can define the problem by asking questions of the user. Here are a few questions to ask the user to aid in determining what the problem is, exactly:

Can you show me the problem?This question is one of the best. It allows the user to show you exactly where and when they experience the problem.

How often does this happen?This question establishes whether this problem is a one-time occurrence that can be solved with a reboot, or whether a specific sequence of events causes the problem to happen. The latter usually indicates a more serious problem that may require software installation or hardware replacement.

Has any new hardware been installed recently?New hardware can mean compatibility problems with existing devices. Some Plug-and-Play devices install with the same resource settings as an existing device. This can cause both devices to become disabled.

Have any other changes been made to the computer recently?If the answer is “Yes,” ask if the user can remember approximately when the change was made. Then ask them approximately when the problem started. If the two dates seem related, then there’s a good chance that the problem is related to the change. If it’s a new hardware component, check to see that the hardware component was installed correctly.

Step 2: Check the Simple Stuff First

This step is the one that most experienced technicians overlook. Often, computer problems are the result of something simple. Technicians overlook these problems because they’re so simple that the technicians assume they couldn’t be the problem. Some examples of simple problems are shown here:

Is it plugged in?And plugged in on both ends? Cables must be plugged in on both ends in order to function correctly. Cables can be easily tripped over and inadvertently pulled from their sockets.

Is it turned on?This one seems the most obvious, but we’ve all fallen victim to it at one point or another. Computers and their peripherals must be turned on in order to function. Most have power switches with LEDs that glow when the power is turned on.

Is the system ready?Computers must be ready before they can be used. Ready means the system is ready to accept commands from the user. An indication that a computer is ready is when the operating system screens come up and the computer presents you with a menu or a command prompt. If that computer uses a graphical interface, the computer is ready when the mouse pointer appears. Printers are ready when the On Line or Ready light on the front panel is lit.

Do the chips and cables need to be reseated?You can solve some of the strangest problems (random hang-ups or errors) by opening the case and pressing down on each socketed chip. This remedies the chip-creep problem mentioned earlier in this chapter. In addition, you should reseat any cables to make sure that they are making good contact.

Step 3: Check to See If It’s User Error

This error is common but preventable. The indication that a problem is due to user error is when a user says they can’t perform some very common computer task, such as printing or saving a file. As soon you hear these words, you should begin asking questions to determine if it is simply a matter of teaching the user the correct procedure. A good question to ask following their statement of the problem would be, “Were you ever able to perform that task?” If they answer “No” to this question, it means they are probably doing the procedure wrong. If they answer “Yes,” you must move on to another set of questions.

The Social Side of Troubleshooting

When you’re looking for clues as to the nature of a problem, no one can give you more information than the person who was there when it happened. They can tell you what led up to the problem, what software was running, and the exact nature of the problem (“It happened when I tried to print”), and they can help you re-create the problem, if possible.

Use questioning techniques that are neutral in nature. Instead of saying, “What were you doing when it broke?” be more compassionate and say, “What was going on when the computer decided not to work?” It sounds silly, but these types of changes can make your job a lot easier!

Step 4: Reboot the Computer

It is amazing how often a simple computer reboot can solve a problem. Rebooting the computer clears the memory and starts the computer with a clean slate. Whenever I perform phone support, I always ask the customer to reboot the computer and try again. If rebooting doesn’t work, try powering down the system completely and then powering it up again. More often than not, that will solve the problem.

Step 5: Determine If the Problem Is Hardware- or Software-Related

This step is important because it determines what part of the computer you should focus your troubleshooting skills on. Each part requires different skills and different tools.

To determine if a problem is hardware- or software-related, you can do a few things to narrow down the issue. For instance, does the problem manifest itself when you use a particular piece of hardware (a modem, for example)? If it does, the problem is more than likely hardware-related.

This step relies on personal experience more than any of the other steps do. You will without a doubt run into strange software problems. Each one has a particular solution. Some may even require reinstallation of the software or the entire operating system.

Step 6: If the Problem Is Hardware-Related, Determine Which Component Is Failing

Hardware problems are pretty easy to figure out. If the modem doesn’t work, and you know it isn’t a software problem, the modem is probably the piece of hardware that needs to be replaced.

With some of the newer computers, several components are integrated into the motherboard. If you troubleshoot the computer and find a hardware component to be bad, there’s a good chance that the bad component is integrated into the motherboard (for example, the parallel port circuitry) and the whole motherboard must be replaced—an expensive proposition, to be sure.

Step 7: Check Service Information Sources

As you may (or may not) have figured out by now, I’m fond of old sayings. There’s another old saying that applies here: “If all else fails, read the instructions.” The service manuals are your instructions for troubleshooting and service information. Almost every computer and peripheral made today has service documentation in the form of books, service CD-ROMs, and websites. The latter of the three is growing in popularity as more and more service centers get connections to the Internet.

Step 8: If It Ain’t Broke...

When doctors take the Hippocratic oath, they promise to not make their patients any sicker than they already were. Technicians should take a similar oath. It all boils down to, “If it ain’t broke, don’t fix it.” When you troubleshoot, make one change at a time. If the change doesn’t solve the problem, revert the computer to its previous state before making a different change.

Step 9: Ask for Help

If you don’t know the answer, ask one of your fellow technicians. They may have run across the problem you are having and know the solution.

This solution does involve a little humility. You must admit that you don’t know the answer. It is said that the beginning of wisdom is “I don’t know.” If you ask questions, you will get answers, and you will learn from the answers. Making mistakes is valuable as well, as long as you learn from them.


Throughout my career in the computer business, the reluctance to share information has been the thing that most concerns me about this industry. As computer professionals, we are valued due to the extent of our knowledge. Some of us intend to keep our value high by limiting the flow of knowledge to others. My position is different than that of those tight-lipped people. I like to help and to teach. This factor has been my best asset as I climbed from the help desk to become an IS manager. The most amusing thing is that despite my impressive title, many certifications, and two published technical books, I still ask for advice and help on a daily basis. If I don’t know the answer, I ask, and it doesn’t bother me a bit. If I know and I’m asked, I share and try to bring the other person to the understanding that I have of that particular subject. One of the greatest assets you can have is another opinion or another person to bounce ideas off.

Exam Essentials

Know the basic steps of troubleshooting.Troubleshooting is a process of trial and error. For the exam and your career, use this system to diagnose and repair hardware-related issues.

Check your information sources.Service manuals are your instructions for troubleshooting and service information. Almost every computer and peripheral made today has service documentation in the form of books, service CD-ROMs, and websites.

Ask for help.If you don’t know the answer, ask one of your fellow technicians. They may have run across the problem you are having and know the solution. This is one thing I feel very strongly about. Don’t be embarrassed to ask, and don’t be too tight-lipped to help others.

Review Questions


Would the POST test identify a problem with RAM?

yes. one of the components the post checks is the ram.


If a legacy serial port is physically fine but does not show up in Windows’ Device Manager, how might you enable it?

it may be disabled in bios setup; try enabling it there.


When testing a cable for broken wires, what type of measurement should the multimeter be set up to register?

ohms (resistance).


If an IDE drive’s Master/Slave jumper was set incorrectly, and therefore the drive did not appear in Windows, would the drive appear in BIOS Setup?



What AT command resets the modem?

 atz .


If the mouse pointer is jumping around erratically on-screen, how can you fix the problem?

clean the mouse.


If a peripheral device such as a sound card shows up in Device Manager as an Unknown Device after being detected by Plug and Play, how can you get it to be recognized fully?

run the setup software that came with it.


If a notebook PC will not wake up from Standby mode, how can you force it to start up?

remove all power from the pc, including removing the battery.


A client calls you, saying his PC will power up, but not boot. What are some questions you would ask to help narrow down the problem?

yours may vary, but here are some possible questions: (1) have you installed any new hardware recently? (2) have you installed any new software? (3) what were you doing when the problem occurred? (4) will the pc boot into safe mode? (5) will the pc boot from a floppy? (6) does the problem happen every time you try to boot, or only sporadically?


True or false: The best way to clean a mouse’s ball is with alcohol.

false. alcohol dries out the rubber. the mouse ball is one of the few computer components that should be cleaned with soap and water.



Yes. One of the components the POST checks is the RAM.


It may be disabled in BIOS Setup; try enabling it there.


Ohms (resistance).






Clean the mouse.


Run the Setup software that came with it.


Remove all power from the PC, including removing the battery.


Yours may vary, but here are some possible questions: (1) Have you installed any new hardware recently? (2) Have you installed any new software? (3) What were you doing when the problem occurred? (4) Will the PC boot into safe mode? (5) Will the PC boot from a floppy? (6) Does the problem happen every time you try to boot, or only sporadically?


False. Alcohol dries out the rubber. The mouse ball is one of the few computer components that should be cleaned with soap and water.

A+ Fast Pass
A+ Fast Pass
ISBN: 735608547
Year: 2002
Pages: 103 © 2008-2020.
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