Download IC100D Chapter 11

OBJECTIVES
1. Describe the characteristics of a good work space.
2. Outline steps for using a digital multimeter to perform voltage,
resistance, and current checks on a system, as well as identify common
DMM tests associated with personal computers.
3. List preliminary steps for diagnosing computer problems.
4. Perform visual inspections of a system.
5. Describe the three general categories of problems into which symptoms
can be grouped, and differentiate between them.
6. Differentiate between software- and hardware-based troubleshooting
techniques.
7. Use disk-based diagnostic tools to isolate system problems.
8. Describe the function of a POST card.
9. Describe quick checks that can be used to determine the nature of system
hardware problems.
10. Describe FRU-level troubleshooting.
11. Describe the steps for isolating power supply problems.
12. Outline checks to isolate problems that produce a dead system.
13. Discuss methods of dealing with symptoms that are not defined well
enough to point to a particular component.
Identify basic troubleshooting procedures and
good practices for eliciting problem symptoms
from customers:
Troubleshooting/isolation/problem
determination
Determine whether a problem is a
hardware or software problem
Gather information from user regarding:
Customer environment
Symptoms/Error codes
Situation when the problem occurred
The following list identifies some of the
organizational aids you need:
A parts organizer to keep track of small parts
such as screws and connectors you may remove
from the device. This organizer need not be
extravagant. A handful of paper cups or clear
plastic sandwich bags will do nicely.
A small note pad or notebook to keep track of
your assembly/troubleshooting steps.
The following list identifies some of the
organizational aids you need: (continued)
A roll of athletic or masking tape. You can use
the tape to make tags and labels to help
identify parts, where they go, and how they are
connected in the circuit. Take the time to write
notes and stick them on your parts organizers,
circuit boards, and cables you remove from the
system, and so forth.
Figure 11-1: IC Pullers
Figure 11-2: Hand Tools
Figure 11-3: Digital Multimeter
WARNING
Setting the meter—It is normal practice
to first set the meter to its highest voltage
range to make certain that the voltage
level being measured does not damage
the meter.
Figure 11-4: dc Voltage Check
WARNING
Power off—Unlike the voltage check,
resistance checks are always made with
power removed from the system.
TEST TIP
Know what readings to expect from
a multimeter when testing fuses,
speakers, and typical power-supply
voltages in a PC.
Careful observation—The most important thing
to do when checking a malfunctioning device is
to be observant. Begin by talking to the person
who reported the problem. You can obtain many
clues from this person. Careful listening also is a
good way to eliminate the user as a possible
cause of the problems. Part of the technician’s
job is to determine whether the user could be
the source of the problem—either trying to do
things with the system that it cannot do, or not
understanding how some part of it is supposed
to work.
TEST TIP
Be well aware that the user is one of
the most common sources of PC
problems. In most situations, your
first troubleshooting step should be
to talk to the user.
Error message formats—Whenever a
self-test failure or setup mismatch is
encountered, the BIOS may indicate the
error through a blank screen, or a visual
error message on the video display, or an
audio response (beep codes) produced by
the system’s speaker.
Figure 11-5: Error Messages and Beep Codes
Figure 11-5:
Error
Messages and
Beep Codes
(continued)
Check the outside—Check all
externally accessible switch settings.
Documenting things—Take time to document the
problem, including all of the tests you perform
and their outcomes. Your memory is never as
good as you think it is, especially in stressful
situations such as with a down computer. This
recorded information can prevent you from
making repetitive steps that waste time and may
cause confusion. This information also proves
very helpful when you move on to more detailed
tests or measurements. Also, label all cables and
connectors prior to removing them. This will
assist you in reconnecting things as you progress
through the troubleshooting process.
Observing bootup—Carefully observing
the steps of a bootup procedure can
reveal a great deal about the nature of
problems in a system. Faulty areas can
be included or excluded from possible
causes of errors during the bootup
process.
The observable actions of a working system’s
cold-boot procedure are listed as follows, in
their order of occurrence:
1
When power is applied, the power supply fan
activates.
2
The keyboard lights flash as the rest of the system
components are being reset.
3
A BIOS message displays on the monitor.
4
A memory test flickers on the monitor.
5
The floppy disk drive access light comes on briefly
(if enabled in the CMOS bootup sequence.)
The observable actions of a working system’s
cold-boot procedure are listed as follows, in
their order of occurrence: (continued)
6
The hard disk drive access light comes on briefly.
7
The system beeps, indicating that it has completed
it power on self tests and initialization process.
8
The floppy disk drive access light comes on briefly
before switching to the hard drive. At this point in
the process, the BIOS is looking for additional
instructions (boot information), first from the
floppy drive and then from the hard drive
(assuming that the CMOS setup is configured for
this sequence).
The observable actions of a working system’s
cold-boot procedure are listed as follows, in
their order of occurrence: (continued)
9
For Windows machines, the “Starting Windows
message” appears on the screen.
TEST TIP
Memorize the order of the series of
observable events that occur during
the normal (DOS) boot up.
You can still group errors that occur before
the beep into two distinct categories:
Configuration errors
Hardware failures
Configuration problems—You can trace
the majority of all problems that occur
in computer systems back to
configuration settings.
It is usually necessary to run the system’s CMOS
setup utility in the following three situations:
1
The first situation occurs when the system is
first constructed.
2
The second occurrence happens if it becomes
necessary to replace the CMOS backup battery
on the system board.
3
Whenever a new or different option is added to
the system (such as a hard drive, floppy drive,
or video display), it may be necessary to run
the Setup utility (although see the note “CMOS
Setup Utility and Plug-and-Play”).
CMOS Setup Utility and Plug-and-Play—In
most newer systems, the BIOS and operating
system use Plug-and-Play (PnP) techniques to
detect new hardware that has been installed in
the system. These components work together
with the device to allocate system resources
for the device. In some situations, the PnP
logic will not be able to resolve all the system’s
resource needs and a configuration error will
occur. In these cases, the user must manually
resolve the configuration problem.
Table 11-1: Common Configuration Error Codes
TEST TIP
Know the situations that cause
a Press F1 to Continue error
message to display.
Errors that occur between the beep and the
presentation of the operating system’s user
interface (command prompt or GUI) generally
have three possible sources:
Hardware failure (physical problem with the
boot drive)
Corrupted or missing boot files
Corrupted or missing operating system files
Figure 11-6: The Main Menu
Figure 11-7: The System Information Menu
Figure 11-8: The Advanced Diagnostics Tests
Figure 11-9: The Burn-In Test Report
Figure 11-10: A Typical POST Card
Ground yourself—Because there may be
Metal Oxide Semiconductor (MOS)
devices on the board, you want to ground
yourself before performing this test. You
can do so by touching an exposed portion
of the unit’s chassis, such as the top of
the power supply.
Field-Replaceable Units (FRUs) are
the portions of the system that you
can conveniently replace in the field.
TEST TIP
Know which devices in a typical
PC system are FRU devices.
Figure 11-11: The Typical FRUs of a Microcomputer
System
Exchanging FRU components—Once
a hardware error has been indicated,
start troubleshooting the problem by
exchanging components (cards, drives,
etc.) with known good ones.
Write it down—Make certain to take
the time to document the symptoms
associated with the problem,
including all of the tests you make,
and any changes that occur during
the tests. This information can keep
you from making repetitive steps.
Work backwards—Once you have
isolated the problem, and the computer
boots up and runs correctly, work
backwards through the troubleshooting
routines, reinstalling any original boards
and other components removed during
the troubleshooting process.
Error messages typically associated with
configuration problems include the following:
CMOS Display Type Mismatch
CMOS Memory Size Mismatch
CMOS Battery State Low
CMOS Checksum Failure
CMOS System Options Not Set
CMOS Time and Date Not Set
Typical error messages associated with boot-up
problems include the following:
General Failure Error Reading Drive x
Bad or Missing Command Interpreter
Non-System Disk or Disk Error
Bad File Allocation Table
Identify common symptoms and problems associated with each module and how to troubleshoot
and isolate the problems. Contents may include:
Mouse
Parallel ports
Hard drives
Power supply
Motherboards
Modems
BIOS
USB
CMOS
Slot covers
Floppy drive failures
Sound card/audio
Processor/Memory symptoms
Monitor/Video
Large LBA, LBA
POST audible/visual error
codes
Troubleshooting tools (for
example, multimeter)
Typical symptoms associated with power-supply
failures include:
No indicator lights visible, with no disk drive
action, and no display on the screen. Nothing
works, and the system is dead.
The ON/OFF indicator lights are visible, but
there is no disk drive action and no display
on the monitor screen. The system fan may
or may not run.
The system produces a continuous beep tone.
Figure 11-12: Power Supply Interconnections
Special consideration must be taken
when a system is inoperable. In a
totally inoperable system, there are no
symptoms to give clues where to begin
the isolation process. In addition, it is
impossible to use troubleshooting
software or other system aids to help
isolate the problem.
When the system exhibits no signs of life the best
place to start looking for the problem is at the
power supply:
1
Begin by checking the external connections of
the power supply. This is the first step in
checking any electrical equipment that shows
no signs of life.
2
Confirm that the power supply cord is plugged
into a functioning outlet.
3
Check the position of the ON/OFF switch.
4
Examine the power cord for good connection at
the rear of the unit.
When the system exhibits no signs of life the best
place to start looking for the problem is at the
power supply: (continued)
5
Check the setting of the 110/220 switch setting
on the outside of the power supply. The normal
setting for equipment used in the United States
is 110.
6
Check the power at the commercial receptacle
using a voltmeter, or by plugging in a lamp (or
other 110 volt device) into the outlet.
TEST TIP
Remember the first step of checking
out electrical equipment that appears
dead.
WARNING
Turn It Off First!—Before changing any
board or connection, always turn the
system off first. In an ATX-style system,
you should also disconnect the power
cable from the power supply. This is
necessary because even with the power
switch off, there are still some levels of
voltages applied to the system board in
these units.
The presence of the lights and the fan operation
indicate that power is reaching the system and
that at least some portion of the power supply is
functional. This type of symptom results from
the following two likely possibilities:
1
A portion of the power supply has failed, or is
being overloaded. One or more of the basic
voltages supplied by the power supply is
missing while the others are still present.
The presence of the lights and the fan operation
indicate that power is reaching the system and
that at least some portion of the power supply is
functional. This type of symptom results from
the following two likely possibilities:
2
A key component on the system board has failed,
preventing it from processing, even though the
system has power. A defective capacitor across
the power input of the system board can
completely prevent it from operating.
Figure 11-13: Power Supply Connections
Typical steps for removing a power supply:
1
Disconnect the exterior power connections
from the system unit
a. Unplug the power cable from the commercial
receptacle
b. Disconnect the monitor’s power cable from
the power supply
Typical steps for removing a power supply:
(continued)
2
Disconnect the interior power connections
a. Disconnect the power supply connections from the
system board
b. Disconnect the power supply connector from the
floppy disk drive
c. Disconnect the power supply connector from the
hard disk drive
d. Disconnect the power supply connector from the
CD-ROM drive (if present)
e. Disconnect the power supply connector to the front
panel switch (if used in your case style)
Typical steps for removing a power supply:
(continued)
3
Remove the power supply unit from the system
a. Remove the 4 retaining screws that secure the
power supply unit to the rear of the system unit
(Note: in some AT style cases, an additional pair
of screws are used along the front edge of the
power supply to secure it to the metal bracket it is
mounted on)
b. Store the screws properly
c. Remove the power supply from the system unit by
lifting it out of the unit
Typical symptoms associated with system board
hardware failures include:
The On/Off indicator lights are visible, the display
is visible on the monitor screen, but there is no
disk drive action and no bootup.
The On/Off indicator lights are visible, the hard
drive spins up, but the system appears dead and
there is no bootup.
The system locks up during normal operation.
The system produces a beep code with 1, 2, 3, 5, 7,
or 9 beeps is produced.
Typical symptoms associated with system board
hardware failures include: (continued)
The system produces a beep code of 1 long and 3
short beeps is produced.
The system will not hold date and time.
An “8042 Gate A20 Error” message displays—
Error getting into Protected mode.
An “Invalid Switch Memory Failure” message
displays.
A “DMA Error” message displays—DMA
Controller failed page register test.
Typical symptoms associated with system board
hardware failures include: (continued)
A “CMOS Battery Low” message displays,
indicating failure of CMOS battery or CMOS
checksum test.
A “CMOS System Option Not Set” message
displays, indicating failure of CMOS battery or
CMOS checksum test.
A “CMOS Checksum Failure” message displays,
indicating CMOS battery low or CMOS checksum
test failure.
Typical symptoms associated with system board
hardware failures include: (continued)
A 201 error code displays, indicating a RAM
failure.
A parity check error message displays, indicating
a RAM error.
TEST TIP
Memorize standard IBM error
code numbers.
Typical symptoms associated with system board
setup failures include:
A “CMOS Inoperational” message displays,
indicating failure of CMOS shutdown register.
A “Display Switch Setting Not Proper” message
displays—Failure to verify display type.
A “CMOS Display Mismatch” message displays—
Failure of display type verification.
A “CMOS Memory Size Mismatch” message
displays—System Configuration and Setup failure.
Typical symptoms associated with system board
setup failures include: (continued)
A “CMOS Time & Date Not Set” message
displays—System Configuration and Setup
failure.
An IBM-compatible error code displays,
indicating that a configuration problem has
occurred.
Typical symptoms associated with system board
I/O failures include the following:
Speaker doesn’t work during operation. The rest
of the system works, but no sounds are produced
through the speaker.
Keyboard does not function after being replaced
with a known good unit.
Figure 11-14: Moving Information to an I/O Port
Figure 11-15: Speaker-Related Components
In Pentium-based systems, check the
advanced CMOS configuration and
enabling settings in the BIOS and
Chipset Features screens. These settings
usually include the disk drives,
keyboard, and video options, as well as
on-board serial and parallel ports.
Figure 11-16: BIOS Enabling Settings
Typically, if the boot-up process reaches the
point where the system’s CMOS configuration
information displays onscreen, you can safely
assume that no hardware configuration conflicts
exist in the system’s basic components. After
this point in the boot-up process, the system
begins loading drivers for optional devices and
additional memory. If the error occurs after the
CMOS screen displays and before the boot-up
tone, you must clean boot the system and singlestep through the remainder of the boot-up
sequence.
Figure 11-17: The System Board Voltage Check
Location
TEST TIP
Know what type of failures hardand soft-memory errors are and
how they affect the system.
TEST TIP
Know the effects on the system of
heat buildup and microprocessor
fan failures.
Figure 11-18: Keyboard-Related Components
Typical symptoms associated with keyboard
failures include the following:
No characters appear onscreen when entered
from the keyboard.
Some keys work, whereas others do not work.
A “Keyboard Is Locked—Unlock It” error
displays.
A “Keyboard Error—Keyboard Test Failure”
error displays.
A “KB/Interface Error—Keyboard Test
Failure” error displays.
Typical symptoms associated with keyboard
failures include the following: (continued)
An error code of 6 short beeps is produced
during bootup.
Wrong characters display.
An IBM-compatible 301 error code displays.
TEST TIP
Memorize the IBM-compatible
error codes.
TEST TIP
Know the most common conditions
that will produce a keyboard error
message.
TEST TIP
Be aware that standard 5-pin DIN
and PS/2 mini-DIN keyboards
cannot be hot swapped and that
doing so can cause damage to the
keyboard and system board.
TEST TIP
Be aware of the condition that
causes the cursor to jump and
freeze on the display.
Figure 11-19: Mouse Properties
Figure 11-20: The Joystick Properties Dialog Box
Figure 11-21: Video-Related Components
Figure 11-22: Video Failures
Other common symptoms associated with
display problems include the following:
No display.
Wrong characters displayed onscreen.
Diagonal lines onscreen (no horizontal control).
Display scrolls (no vertical control).
An error code of 1 long and 6 short beeps is
produced by the system.
A “Display Switch Setting Not Proper—Failure
to verify display type” error displays.
Other common symptoms associated with
display problems include the following:
(continued)
A “CMOS Display Mismatch—Failure to verify
display type” error displays.
An error code of 1 long and 2 short beeps
indicates a display adapter problem.
Figure 11-23: Video Adapters Resources
Figure 11-24: The Circuitry Inside a Typical CRT
WARNING
Lethal voltage levels—You must exercise
great caution when opening or working
inside the monitor. The voltage levels
present during operation are lethal.
Electrical potentials as high as 25,000V
are present inside the unit when it is
operating.
TEST TIP
Memorize the values of lethal voltage
associated with the inside of the CRT
video monitor. The values given on
tests may not be exactly the same as
those stated in the textbook, but they
will be in the same high range.
Typical symptoms associated with floppy disk
drive (FDD) failures during boot up include the
following:
FDD errors are encountered during bootup.
The front-panel indicator lights are visible,
and the display is present on the monitor
screen, but there is no disk drive action and
no boot up.
An IBM-compatible 6xx (that is, 601) error
code displays.
Typical symptoms associated with floppy disk
drive (FDD) failures during boot up include the
following: (continued)
An FDD Controller Error message displays,
indicating a failure to verify the FDD setup
by the System Configuration file.
The FDD activity light stays on constantly,
indicating that the FDD signal cable is
reversed.
Additional FDD error messages commonly
encountered during normal system operation
include:
Disk Drive Read Error messages.
Disk Drive Write Error messages.
Disk Drive Seek Error messages.
No Boot Record Found message, indicating
that the system files in the disk’s boot sector
are missing or have become corrupt.
Additional FDD error messages commonly
encountered during normal system operation
include: (continued)
The system stops working while reading a
disk, indicating that the contents of the disk
have become contaminated.
The drive displays the same directory listing
for every disk inserted in the drive, indicating
that the FDD’s disk-change detector or signal
line is not functional.
TEST TIP
Memorize the IBM error codes
for different types of hardware
devices.
Causes of floppy disk problems—A number
of things can cause improper floppy disk
drive operation or disk drive failure. These
items include the use of unformatted disks,
incorrectly inserted disks, damaged disks,
erased disks, loose cables, drive failure,
adapter failure, system board failure, or a
bad or loose power connector.
Figure 11-25: FDD-Related Components
Levels of troubleshooting—Basically
three levels of troubleshooting apply
to FDD problems: configuration, the
software level, and the hardware level.
No Windows-level troubleshooting
applies to floppy disk drives.
Typical symptoms associated with hard disk
drive failures include:
The computer does not boot up when turned on.
The computer boots up to a system disk in the A:
drive, but not to the hard drive, indicating that
the system files on the HDD are missing or have
become corrupt.
No motor sounds are produced by the HDD while
the computer is running. (In desktop units, the
HDD should always run when power is applied to
the system—this also applies to portables because
of their advanced power-saving features.)
Typical symptoms associated with hard disk
drive failures include: (continued)
An IBM-compatible 17xx error code is produced
on the monitor screen.
In HDD Controller Failure message displays,
indicating a failure to verify hard disk setup by
system configuration file error.
A C: or D: Fixed Disk Drive Error message
displays, indicating a hard disk CMOS setup
failure.
Typical symptoms associated with hard disk
drive failures include: (continued)
An Invalid Media Type message displays,
indicating the controller cannot find a
recognizable track/sector pattern on the drive.
A No Boot Record Found, a Non-System Disk or
Disk Error, or an Invalid System Disk message
displays, indicating that the system boot files are
not located in the root directory of the drive.
The video display is active, but the HDD’s
activity light remains on and no boot up occurs,
indicating that the HDD’s CMOS configuration
information is incorrect.
Typical symptoms associated with hard disk
drive failures include: (continued)
An Out of Disk Space message displays,
indicating that the amount of space on the disk is
insufficient to carry out the desired operation.
A Missing Operating System, a Hard Drive Boot
Failure, or an Invalid Drive or Drive
Specification message displays, indicating that
the disk’s master boot record is missing or has
become corrupt.
Typical symptoms associated with hard disk
drive failures include: (continued)
A No ROM BASICS—System Halted, or ROM
BASIC Interpreter Not Found message displays,
followed by the system stopping, indicating that
no master boot record was found in the system.
This message is produced only by PCs, XTs, and
some clones.
A Current Drive No Longer Valid message
displays, indicating that the HDD’s CMOS
configuration information is incorrect or has
become corrupt.
TEST TIP
Be able to describe the conditions
indicated by Invalid Drive or Drive
Specification, Missing Operating
System, and the Hard Drive Boot
Failure error messages.
Figure 11-26: Hard Disk Drive-Related Components
Hard Drive Systems—Hard drive systems
are very much like floppy drive systems in
structure—they have a controller, one or
more signal cables, a power cable, and a
drive unit. The troubleshooting procedure
typically moves from setup and
configuration, to formatting, and, finally,
into the hardware component isolation
process.
TEST TIP
Know that there can only be one
master drive selection on each IDE
channel.
TEST TIP
Be aware that mixing drive types
on a single signal cable can disable
both devices.
TEST TIP
Know that in newer systems, SCSI
drive support and large drive
support are both enabled in the
BIOS.
If the clean boot disk has a copy of the FDISK
program on it, attempt to restore the drive’s
master boot record (including its partition
information) by typing the following at the A:
prompt:
FDISK /MBR
Provided that the hard disk can be accessed
with the DIR command, type and enter the
following command at the DOS prompt (with
the Clean Boot Disk still in the A: drive):
SYS C:
TEST TIP
Know how and when to use the
FDISK /MBR and SYS C:
commands.
Three conditions will produce a Bad or Missing
COMMAND.COM error message. These
conditions include the following:
1
The first condition occurs when the
COMMAND.COM file cannot be found on the
hard drive (because it has become corrupted),
and no bootable disk is present in drive A:.
2
The COMMAND.COM file is not located in
the hard drive’s root directory. This message is
likely when installing a brand new hard drive,
or a new DOS version.
Three conditions will produce a Bad or Missing
COMMAND.COM error message. These
conditions include the following: (continued)
3
The message also occurs if the user
inadvertently erases the COMMAND.COM file
from the root directory of the hard drive.
Figure 11-27: IDE Master/Slave Settings
The troubleshooting steps for a CD-ROM
drive are almost identical to those of an
HDD system. The connections and data
paths are very similar. Basically, four levels
of troubleshooting apply to CD-ROM
problems. These are the configuration level,
the DOS level, the Windows level, and the
hardware level.
Figure 11-28: Components and Drivers Associated
with CD-ROMs
Figure 11-29: Control Panel/Device Manager/Settings
TEST TIP
Know how to retrieve a CD from
a disabled CD-ROM drive.
TEST TIP
Remember that card-mounted IDE
host adapters can be used to repair
system boards with defective onboard IDE controllers and to
upgrade older IDE systems.
There are basically three levels of testing
that apply to troubleshooting port
problems. These are the DOS level, the
Windows level, and the hardware level.
Generally, there are only four possible causes
for a problem with a device connected to an
I/O port:
The port is defective.
The software is not configured properly
for the port.
The connecting signal cable is bad.
The attached device is not functional.
Figure 11-30: Components Associated with I/O Ports
Typical symptoms associated with serial, parallel,
or game port failures include:
A 199, 432, or 90x IBM-compatible error code
displays on the monitor (Printer Port).
The on-line light is on but no characters are
printed by the printer.
An 110x IBM-compatible error code displays
on the monitor (Serial Port).
Device not found error message displays, or
you have an unreliable connection.
Input device does not work on the game port.
Checking ports on newer Pentium-based
systems—With newer Pentium systems,
you must check the advanced CMOS
setup to determine whether the port in
question has been enabled, and, if so,
whether it has been enabled correctly.
Figure 11-31: Moving Information Through an AT
Port
Figure 11-32: Parallel Port Loopback Connections
Figure 11-33: Serial Port Loopback Connections
Figure 11-34: Accessing Windows 95 Troubleshooting
Help
Figure 11-35: Port Settings Entry
Check under the Windows 9x Control Panel/
System/Device Manager window for correct
serial port settings.
1
Click the Port Settings option to see the setup
for the ports. Most serial printers use settings
of 9600 Baud, No Parity, 8 Bits, 1 Stop Bit,
and Hardware Handshaking (Xon-Xoff).
2
Click the Resources button to determine the
IRQ Setup for the port.
3
Check the user’s manual to document the
correct settings for the device using the port
in question.
Problems associated with USB ports can be
addressed in three general areas:
The USB hardware device
The USB controller
The USB drivers
Figure 11-36: The USB Controller Properties Page
Authority Needed—To use the Windows 2000
Device Manager utility to troubleshoot USB
problems, you must be logged on as an
administrator, or as a member of the
Administrators group or as a member of the
Administrators group.
Removing Potentially Conflicting USB Drivers:
1
Disconnect any USB devices connected to the
system and start the system in Safe mode.
2
Under Windows 2000, you are asked about
which operating system to use. Use the up- and
down-arrow keys to highlight Windows 2000
Professional or Windows 2000 Server, and then
press ENTER.
If alert messages appear, read each alert and
then click the OK button to close it.
Removing Potentially Conflicting USB Drivers:
(continued)
3
Open the Device Manager, click the USB device,
and then click the Remove option.
4
Click the Start menu, select the Shut Down option
followed by the Restart entry, and then click the
OK button.
5
Connect the USB device directly to the USB port
on your computer. If the system does not
autodetect the device, you must install the drivers
manually. You may need drivers from the device
manufacturer to perform this installation.
Most scanners have three important
configuration parameters to consider.
These are: the I/O address, the IRQ
setting, and the DMA channel setting.
Figure 11-37: Scanner-Related Components
Typical symptoms associated with IRQ
conflicts include:
The image on the screen appears misaligned.
The scanning function appears to be activated
and the scanner light comes on, but no image
is produced onscreen.
The basic components associated with
the tape drive include: the tape drive, the
signal cable, the power connection, the
controller, and the tape drive’s operating
software.
Common points to check with the tape include:
Is the tape formatted correctly for
use with the drive in question?
Is the tape inserted securely in the
drive?
Is the tape write-protected?
Is the tape broken or off the reel in
the cartridge?
A section on troubleshooting modems has
to be subdivided into two segments:
external modems
internal modems
Figure 11-38: Internal and External Modem
Components
Typical symptoms associated with modem
failures include:
No response from the modem.
Modem does not dial out.
Modem does not connect after number
has been dialed.
Modem does not transmit after making
connection with remote unit.
Cannot get modem installed properly
for operation.
Typical symptoms associated with modem
failures include: (continued)
Garbled messages are transmitted.
Cannot terminate a communication
session
Cannot transfer files.
As stated earlier, every COM port on a PC
requires an IRQ line in order to signal the
processor for attention. In most PC systems,
two COM ports share the same IRQ line. The
IRQ4 line works for COM1 and COM3, and
the IRQ3 line works for COM2 and COM4.
This is common in PC compatibles. The
technician must make sure that two devices
are not set up to use the same IRQ channel.
TEST TIP
Be aware that the system may conflict
with non-PNP devices for resources if
it is not informed they are have been
reserved.
The modem’s IRQ setting is typically IRQ=3.
Other common modem settings are:
COM1 with IRQ=4, 5, or 7
COM2 with IRQ=3, 5, or 7
COM3 with IRQ=4, 5, or 7
COM4 with IRQ=3, 5, or 7
The modem’s IRQ setting is typically
IRQ=3. Other common modem settings
are:
Setting up user accounts
Sharing network resources
Assigning users permission to
access resources
Change the DTR setting by entering AT&Dn.
When:
n = 0 the modem ignores the DTR line
n = 1 the modem goes to async command
state when DTR goes off
n = 2 DTR off; switches modem to off-hook
and back to Command mode
n = 3 DTR switching off initializes modem
During the data transfer, both modems
monitor the signal level of the carrier to
prevent the transfer of false data due to
signal deterioration. If the carrier signal
strength drops below some
predetermined threshold level, or is lost
for a given length of time, one or both
modems will initiate automatic
disconnect procedures.
Figure 11-39: The Connection Tab of the Standard
Modem Properties Dialog Box
Figure 11-40: The Diagnostics Tab of the Modem
Properties Dialog Box
Modems have the capability to perform three
different kinds of self-diagnostic tests:
The local digital loopback test
The local analog loopback test
The remote digital loopback test
Figure 11-41: Loopback Tests
With an external modem, you can use
the front-panel lights as diagnostic tools
to monitor its operation. You can
monitor the progress of a call, and its
handling, along with any errors that
may occur.
Figure 11-42: Modem Front Panel Indicator
Some very basic components are
involved in the audio output of most
computer systems: a sound card, some
speakers, the audio-related software,
and the host computer system. Several
software diagnostic packages enable
you to test sound card operation.
Figure 11-43: Sound Card-Related Components
TEST TIP
Know how to correct a balance
problem that occurs with add
on stereo speakers.
Typical symptoms associated with
multimedia failures include the following:
Sound not working.
The system will not capture video.
Software cannot access the CD-ROM.
The system will not play video.
Figure 11-44: Multimedia Components
Identify the ramifications of repairs on the
network. Examples include:
Reduced bandwidth
Loss of data
Network slowdown
Figure 11-45: Network-Related Components
Be aware that in a network environment,
no unit really functions alone. Unlike
working on a stand-alone unit, the steps
performed on a network computer may
affect the operation of other units on the
network.
For example, disconnecting a unit from a
network that uses coaxial cable creates an
unterminated condition in the network. This
condition can cause several different types of
problems:
Data moving through the network can be lost.
A general slowdown of data movement across
the network can occur due to reduced
bandwidth.
Nodes may not be able to “see,” or connect to,
each other.
TEST TIP
Be aware of the affects of a missing
terminator or bad cable/connector can
have on an Ethernet network.
TEST TIP
Be aware of the effects that running
applications across the network can
have on its performance.
TEST TIP
Be aware that many ISA NIC cards
are not PnP configurable, so they must
be configured manually.
One of the major concerns in most network
environments is data security. Since all of
the data around the network is potentially
available to anyone else attached to the net,
all LAN administration software employs
different levels of security. Passwords are
typically used at all software levels to lock
people out of hardware systems, as well as
out of programs and data files.
No Network Node is an Island—In a network, no
node is an island, and every unit has an impact on
the operation of the network when it is on line.
Changes made in one part of a network can cause
problems, and data loss, in other parts of the
network. You should be aware that changing
hardware and software configuration settings for
the adapter can have adverse effects when the
system is returned to the network. In addition,
changing hard drives in a network node can have
a negative impact on the network when the unit is
brought back on line.
Figure 11-46: Cable Tester
Figure 11-47: Isolating Network Printing Problems
KEY POINTS
It is normal practice to first set the meter
to its highest voltage range to make certain
that the voltage level being measured does
not damage the meter.
KEY POINTS
Unlike the voltage check, resistance checks
are always made with power removed from
the system.
KEY POINTS
The most important thing to do when checking a
malfunctioning device is to be observant. Begin by
talking to the person who reported the problem.
Many clues can be obtained from this person.
Careful listening is also a good way to eliminate the
user as a possible cause of the problems occurring.
Part of the technician’s job is to determine whether
the user could be the source of the problem—either
trying to do things with the system that it cannot
do, or not understanding how some part of it is
supposed to work.
KEY POINTS
Whenever a self-test failure or setup
mismatch is encountered, the BIOS may
indicate the error through a blank screen,
or a visual error message on the video
display, or through an audio response
(beep codes) produced by the system’s
speaker.
KEY POINTS
Check all externally accessible switch
settings.
KEY POINTS
Take the time to document the problem,
including all of the tests you perform and
their outcomes. Your memory is never as
good as you think it is, especially in stressful
situations such as with a down computer.
This recorded information can prevent you
from making repetitive steps that waste time
and may cause confusion. This information
will also be very helpful when you move on
to more detailed tests or measurements.
KEY POINTS
Carefully observing the steps of a bootup
procedure can reveal a great deal about the
nature of problems in a system. Faulty areas
can be included or excluded from possible
causes of errors during the bootup process.
KEY POINTS
The majority of all problems that occur
in computer systems are in the area of
configuration settings.
KEY POINTS
In most newer systems, the BIOS and
operating system use Plug-and-Play
techniques to detect new hardware that has
been installed in the system. These
components work together with the device to
allocate system resources for the device. In
some occasions, the PnP logic will not be able
to resolve all of the system’s resource needs
and a configuration error will occur. In these
cases, the user will be required to manually
resolve the configuration problem.
KEY POINTS
Since there may be MOS (Metal Oxide
Semiconductor) devices on the board, you’ll
want to ground yourself before performing
this test. This may be done by touching an
exposed portion of the unit’s chassis, such
as the top of the power supply.
KEY POINTS
Field Replaceable Units (FRUs) are
the portions of the system that can be
conveniently replaced in the field.
KEY POINTS
Once a hardware error has been indicated,
start troubleshooting the problem by
exchanging components (cards, drives, etc.)
with known good ones.
KEY POINTS
Make certain to take the time to document
the symptoms associated with the problem,
including all of the tests you make, and any
changes that occur during the tests. This
information can keep you from making
repetitive steps.
KEY POINTS
Once you have isolated the problem, and the
computer boots up and runs correctly, work
backwards through the troubleshooting
routines, reinstalling any original boards
and other components removed during the
troubleshooting process.
KEY POINTS
Special consideration must be taken when a
system is inoperable. In a totally inoperable
system, there are no symptoms to give clues
where to begin the isolation process. In
addition, it is impossible to use
troubleshooting software or other system
aids to help isolate the problem.
KEY POINTS
In Pentium-based systems, check the
Advanced CMOS configuration and
enabling settings in the BIOS and Chipset
Features screens. These settings usually
include the disk drives, keyboard, and
video options, as well as on-board serial
and parallel ports.
KEY POINTS
Typically, if the bootup process reaches the
point where the system’s CMOS configuration
information is displayed on the screen, it can be
assumed that no hardware configuration
conflicts exist in the system’s basic components.
After this point in the bootup process, the
system begins loading drivers for optional
devices and additional memory. If the error
occurs after the CMOS screen is displayed and
before the bootup tone, it will be necessary to
clean boot the system and single-step through
the remainder of the bootup sequence.
KEY POINTS
A number of things can cause improper
floppy disk drive operation or disk drive
failure. These items include the use of
unformatted diskettes, incorrectly inserted
diskettes, damaged disks, erased disks, loose
cables, drive failure, adapter failure, system
board failure, or a bad or loose power
connector.
KEY POINTS
There are basically three levels of
troubleshooting that apply to FDD
problems: configuration, the DOS level,
and the hardware level. There is no
Windows-level troubleshooting that
applies to floppy drives.
KEY POINTS
Hard drive systems are very much like floppy
drive systems in structure—they have a
controller, one or more signal cables a power
cable, and a drive unit. The troubleshooting
procedure typically moves from setup and
configuration, to formatting, and, finally, into
the hardware component isolation process.
KEY POINTS
The troubleshooting steps for a CD-ROM
drive are almost identical to those of an
HDD system. The connections and data
paths are very similar. There are basically
four levels of troubleshooting that apply to
CD-ROM problems. These are the
configuration level, the DOS level, the
Windows level, and the hardware level.
KEY POINTS
There are basically three levels of testing
that apply to troubleshooting port problems.
These are the DOS level, the Windows level,
and the hardware level.
KEY POINTS
With newer Pentium systems, it will be
necessary to check the Advanced CMOS
Setup to determine whether the port in
question has been enabled, and, if so,
whether it has been enabled correctly.
KEY POINTS
Most scanners have three important
configuration parameters to consider. These
are the I/O address, the IRQ setting, and the
DMA channel setting.
KEY POINTS
The basic components associated with the
tape drive include the tape drive, the signal
cable, the power connection, the controller,
and the tape drive’s operating software.
KEY POINTS
Every COM port on a PC requires an IRQ
line in order to signal the processor for
attention. In most PC systems, two COM
ports share the same IRQ line. The IRQ4 line
works for COM1 and COM3, and the IRQ3
line works for COM2 and COM4. This is
common in PC-compatibles. The technician
must make sure that two devices are not set
up to use the same IRQ channel.
KEY POINTS
During the data transfer, both modems
monitor the signal level of the carrier to
prevent the transfer of false data due to
signal deterioration. If the carrier signal
strength drops below some predetermined
threshold level, or is lost for a given length
of time, one or both modems will initiate
automatic disconnect procedures.
KEY POINTS
Modems have the capability to perform
three different kinds of self-diagnostic
tests.
KEY POINTS
With an external modem, the front panel
lights can be used as diagnostic tools to
monitor its operation. The progress of a
call, and its handling, can be monitored
along with any errors that may occur.
KEY POINTS
The components involved in the audio
output of most computer systems are very
simple. There is a sound card, some
speakers, the audio-related software, and
the host computer system. Several software
diagnostic packages are available with the
capability of testing sound card operation.
KEY POINTS
Be aware that in a network environment,
no unit really functions alone. Unlike
working on a stand-alone unit, the steps
performed on a network computer may
affect the operation of other units on the
network.
KEY POINTS
One of the major concerns in most network
environments is data security. Since all of
the data around the network is potentially
available to anyone else attached to the net,
all LAN administration software employs
different levels of security. Passwords are
typically used at all software levels to lock
people out of hardware systems, as well as
out of programs and data files.
KEY POINTS
No Network Node is an Island—In a network, no
node is an island, and every unit has an impact
on the operation of the network when it is on
line. Changes made in one part of a network can
cause problems, and data loss, in other parts of
the network. You should be aware that changing
hardware and software configuration settings for
the adapter can have adverse effects when the
system is returned to the network. In addition,
changing hard drives in a network node can have
a negative impact on the network when the unit
is brought back on line.
REVIEW QUESTIONS
1
If the system issues a single beep and the
C:\> prompt appears on the screen, what
condition is indicated?
REVIEW QUESTIONS
2
List the FDD-related hardware components
that should be checked when floppy disk
problems are suspected.
REVIEW QUESTIONS
3
List three situations that would normally
require that the CMOS Setup routines
be run.
REVIEW QUESTIONS
4
What type of problem is indicated by a
“Strike F1 to continue” message during
bootup?
REVIEW QUESTIONS
5
What is the recommended method of
using a digital multimeter to check
voltage in a computer system.
REVIEW QUESTIONS
6
If you are replacing components one
at a time and the system suddenly
begins working properly, what can
be assumed?
REVIEW QUESTIONS
7
List three items commonly tested using
the resistance function of a multimeter.
REVIEW QUESTIONS
8
What resistance reading would normally
be expected from a fuse if it is functional?
REVIEW QUESTIONS
9
If you are measuring across a capacitor
on the system board with a DMM, what
voltage reading would you normally
expect to see from a DMM?
REVIEW QUESTIONS
10 Which non-computer possibility should be
eliminated early in the troubleshooting
process?
REVIEW QUESTIONS
11 What range should the voltage function
of a DMM be set to for an initial
measurement?
REVIEW QUESTIONS
12 Logon passwords and scripts are
designed to _______.
REVIEW QUESTIONS
13 In a LAN environment, access and
privileges to programs and data can be
established by the ______.
REVIEW QUESTIONS
14 What is the first step in checking a
networked computer?
REVIEW QUESTIONS
15 Describe two actions that should be
taken if a networked printer stalls
during a remote printing operation.
EXAM QUESTIONS
1
If an error occurs before the single beep
tone in the bootup sequence, what type of
failure is probable?
a. The problem is probably associated with
the operating system.
b. The BIOS code has become corrupted.
c. A setup or configuration problem.
d. The problem is hardware related.
EXAM QUESTIONS
2
If an error occurs after the single beep in
the bootup process, what type of problem
is likely?
a. The problem is probably associated with
the operating system.
b. The BIOS code has become corrupted.
c. A setup or configuration problem.
d. The problem is hardware related
EXAM QUESTIONS
3
If the system refuses to boot up after a new
component is installed what type of problem
is normally assumed?
a. The problem is probably associated with
the operating system.
b. The BIOS code has become corrupted.
c. A setup or configuration problem has
occurred.
d. A hardware-related problem has occurred.
EXAM QUESTIONS
4
What component has the ability to affect
the operation of all the other sections of
the computer system?
a. The power supply
b. The ROM BIOS
c. The microprocessor
d. The system board
EXAM QUESTIONS
5
What function and reading would be
appropriate for checking a system’s
speaker?
a. Infinity
b. Near zero ohms
c. 4 ohms
d. 8 ohms
EXAM QUESTIONS
6
What type of problem is indicated by a
continuous beep tone from the system?
a. A power supply failure
b. An undefined problem
c. A configuration problem
d. A bootup problem
EXAM QUESTIONS
7
If a system appears to be completely dead,
what item should logically be checked first?
a. The system board
b. The microprocessor
c. The hard disk drive
d. The power supply
EXAM QUESTIONS
8
The error message “Bad File Allocation
Table” indicates _____ problem.
a. an operating system
b. a Run Time
c. a configuration
d. a bootup
EXAM QUESTIONS
9
If a “CMOS” Display Type Mismatch”
message appears on the screen, what type
of error is indicated?
a. An operating system problem
b. A Run Time error
c. A setup or configuration problem
d. A bootup failure
EXAM QUESTIONS
10 Which of the following is not normally
considered an FRU?
a. A system board
b. A floppy disk drive
c. A power supply
d. A video controller IC