Computer Service and Repair, 3rd Edition Page 642 (642 of 976)

642 Computer Service and Repair
The most appropriate utility for diagnosing a problem after the logon is
the System Configuration Utility (msconfig.exe). This and other utilities for
diagnosing problems during this stage are covered in the Recovering from a
System Startup Failure and the Windows Diagnostic Utilities section.
A malicious software program (virus or worm) can attack a
computer at any time, not just after the system logon. For
example, if the MBR is corrupted by a virus, the computer
will fail before switching from text mode to graphic mode.
Typical Startup Problems
Startup problems are a tough class of computer error that you are bound to
run into. A startup problem is a problem that causes the computer to lock up
during the boot process. These problems occur too early in the PC operation to be
solved by system diagnostic tools. This section details some of the most common
and catastrophic boot problems that you will encounter while starting the PC.
Each of the following problems is described as a symptom. Possible solutions
are provided as a guide. The list of symptoms is condensed and centers on the
problems encountered before the boot process is completed. Keep in mind that
there are hundreds of possible computer symptoms. What follows are a few of
the most common system hardware failures during the boot.
Think about the boot process and the steps involved. System boot failures
involve the power supply, CPU, hard drive (boot device), BIOS, CMOS,
system configuration,
autoexec.bat
file, loading of drivers, and the loading of
the operating system. Now let’s look at some of the most common hardware
problems and their symptoms during the boot process.
When reading the list that follows, assume that there is one hard drive
labeled
C
and a CD drive labeled D. Note that these are recommended
procedures, not absolute procedures. Also, viruses can imitate some of the
described symptoms. Always check for the presence of a virus and protect your
disk while doing so.
Remember, always attempt the simplest tests first. Then, move on to the more
complex and labor-intensive tests.
Symptom 1:
There is no power light, no fan running, and no sound of boot operation at
all. It appears that the PC is completely dead.
Items to check:
Before you open the case, make sure the PC is plugged in. Next, check the
power from the wall outlet or power strip or both. Be sure there is power to the
unit. If you have power, then the likely problem is the computer’s power supply.
Open the case and test the power supply outputs. Swapping out power supplies
is generally more cost effective than fixing a broken one.
Symptom 2:
The power light (LED) is on and the fan is running, but there is no activity.
The system appears dead.
Tech Tip:
startup problem
problem that causes
the computer to lock
up during the boot
process.

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Extracted Text (may have errors)

642 Computer Service and Repair
The most appropriate utility for diagnosing a problem after the logon is
the System Configuration Utility (msconfig.exe). This and other utilities for
diagnosing problems during this stage are covered in the Recovering from a
System Startup Failure and the Windows Diagnostic Utilities section.
A malicious software program (virus or worm) can attack a
computer at any time, not just after the system logon. For
example, if the MBR is corrupted by a virus, the computer
will fail before switching from text mode to graphic mode.
Typical Startup Problems
Startup problems are a tough class of computer error that you are bound to
run into. A startup problem is a problem that causes the computer to lock up
during the boot process. These problems occur too early in the PC operation to be
solved by system diagnostic tools. This section details some of the most common
and catastrophic boot problems that you will encounter while starting the PC.
Each of the following problems is described as a symptom. Possible solutions
are provided as a guide. The list of symptoms is condensed and centers on the
problems encountered before the boot process is completed. Keep in mind that
there are hundreds of possible computer symptoms. What follows are a few of
the most common system hardware failures during the boot.
Think about the boot process and the steps involved. System boot failures
involve the power supply, CPU, hard drive (boot device), BIOS, CMOS,
system configuration,
autoexec.bat
file, loading of drivers, and the loading of
the operating system. Now let’s look at some of the most common hardware
problems and their symptoms during the boot process.
When reading the list that follows, assume that there is one hard drive
labeled
C
and a CD drive labeled D. Note that these are recommended
procedures, not absolute procedures. Also, viruses can imitate some of the
described symptoms. Always check for the presence of a virus and protect your
disk while doing so.
Remember, always attempt the simplest tests first. Then, move on to the more
complex and labor-intensive tests.
Symptom 1:
There is no power light, no fan running, and no sound of boot operation at
all. It appears that the PC is completely dead.
Items to check:
Before you open the case, make sure the PC is plugged in. Next, check the
power from the wall outlet or power strip or both. Be sure there is power to the
unit. If you have power, then the likely problem is the computer’s power supply.
Open the case and test the power supply outputs. Swapping out power supplies
is generally more cost effective than fixing a broken one.
Symptom 2:
The power light (LED) is on and the fan is running, but there is no activity.
The system appears dead.
Tech Tip:
startup problem
problem that causes
the computer to lock
up during the boot
process.

Help

Chapter 15 PC Troubleshooting 641
requiring the similar DLL file. While the older game runs perfectly, one or more
of the other games may now run incorrectly or may not run at all.
DLL files usually have a DLL file extension such as mon.dll. Sometimes the
DLL will have an
.exe
file extension. Look at Figure 15-3 to see the results of a
search for files with the “dll” extension. There are 11,497 files that have a “dll”
extension on this particular computer. As you can see, there are thousands of
possible DLL files that can be used as part of software application programs and
hardware drivers.
Blue screen error
The system may also experience a blue screen error. A blue screen error
is a blue screen that appears with an error code and then freezes the system.
Microsoft also refers to blue screen errors as fatal errors, stop errors, and stop error
messages because the system is not recoverable at the time of the error. The system
must be restarted before you can attempt to remedy the problem. Some of the
most common causes for blue screen errors include the following:
✔ Defective hardware, such as memory chips and video adapter cards.
✔ Corrupt files on the hard drive.
✔ System BIOS settings that are beyond the capabilities of the hardware.
✔ Third-party software containing bad code.
✔ Bad code in the Windows operating system.
The error codes displayed on the blue screen can be quite cryptic. You should
copy the error code and use it as a reference when searching Microsoft’s support
Web site.
Figure 15-3.
DLL files are
called by software
applications to
perform common
tasks.
blue screen error
a blue screen that
appears with an
error code and then
freezes the system.
Also referred to by
Microsoft as fatal
errors, stop errors,
and stop error
messages.

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Chapter 15 PC Troubleshooting 643
Items to check:
Check the power supply for a power good signal. The power good signal is
sent back to the BIOS system to signal that the power supply is on and ready.
The signal back should be approximately 5 volts. Pin 1 is usually the power good
pin. Pull the connector back just far enough to check for 5 volts (+/–1 volt). If the
power is very low, there may not be sufficient voltage to power up the system.
The power output does not have to be completely dead to affect startup.
If the power good signal checks out, check the connection from the power
supply to the motherboard. Reseat this connection. Try reseating the CPU.
Sometimes the CPU is not making a good electrical contact. CPUs operate on
fairly low voltages. A slight oxidation buildup on one of the CPU’s pins that is
operating at 3.3 volts is sufficient to render the CPU dead. Cleaning the oxidation
will bring it back.
If you perform all of the listed operations and the system still fails to activate,
you probably have a defective motherboard.
Symptom 3:
The system tries to boot. There are two or more beeps, and then nothing (no
video). The fan is running, and there is a power light.
Items to check:
Make sure the monitor is plugged in correctly (both the data plug and the
power cord). Check the video card. Try reseating the card. If those actions do
not help, try to decode the beep error code. If you have the manual that came
with the motherboard, start there. Newer manuals are often CDs as opposed
to the traditional paper booklet. If there is no manual, look up the BIOS chip
manufacturer on the Internet. First, copy all information from the BIOS chip or
motherboard and then head to the manufacturer’s Web site.
Symptom 4:
You see a setup error indicated on the screen.
Items to check:
This is probably a CMOS setup problem. Access the BIOS setup routine by
using the key combination indicated on the screen. If no setup routine is given, try
key combinations you are familiar with. Some popular combinations can be found
in Figure 3-39 from Chapter 3—Motherboards. You can also look up the keystroke
combination for accessing the BIOS at the BIOS manufacturer’s Web site.
Normally, CMOS settings do not change. However, sometimes when you
install a new hard drive and the drive is automatically detected, the settings
change. Also, if the battery used to hold the CMOS data is going bad, you could
lose the settings. The date and time not matching the true date and time is a good
indication that your battery is going bad.
Be sure to write down the existing CMOS settings before you make any
changes to them. This is extremely important if you are going to try something
like the
Return to default settings
option. When that option is selected, many
settings will change instantly, and you will not be able to tell which settings have
changed or what they changed from. Check the manufacturer’s Web site for the
correct CMOS settings for your particular model of PC.
Sometimes people get curious and go into the BIOS setup to see what it looks
like. They also make changes either intentionally or accidentally. What makes it
worse is they generally deny going into the setup program.

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