Week 1

Process of Fault diagnosis

Before getting into the troubleshooting details, it is important to know about what goes on
during the startup process. The reason is, there are actually quite a few steps that occur in
between switching the power ON and hearing the familiar Windows 95, 98 or Windows
ME/XP startup sounds and seeing the Windows desktop. In fact, there are a whole series of
files that are automatically loaded one after the other when you turn your computer on. The
trick with troubleshooting startup problems is trying to figure out which of those files (or
what step in the process) causes a specific problem in the computer. If we know
approximately where in the startup process the problem occurs (Computer gets stuck), we
can
diagnose the problem easily.

This chapter explains the various problems that occur in a computer and the troubleshooting
procedures.

BIOS

When your computer is first turned on, it automatically loads a program called the BIOS, or
Basic InputOutput System, which is stored on a special chip on your computer's
motherboard. The BIOS is essentially a combination of software and hardware in that it
consists of software, but the contents of that software is stored in a hardware chip.

One of the first things we should see on your computer's monitor when we start the PC is
some type of message like "Hit Ese to enter Setup," although instead of Esc it may say F2 or
F10 or any number of other keys and instead of Setup it may say CMOS Setup or BIOS
Setup
or just CMOS. Make note of the key required to enter the Setup program because we may
need that later (some startup problems can only be solved by changing some BIOS/CMOS
settings via the Setup program).

Power-On Self Test (POST)

The first thing that the BIOS does when it boots the PC is to perform what is called the
Power-On Self-Test, or POST for short. The POST is a built-in diagnostic program that
checks the hardware to ensure that everything is present and functioning properly, before
the
BIOS begins the actual boot. It later continues with additional tests such as the memory test
and then it lists any devices that it finds attached to the computer's internal IDE controller(s).
(that is seen on the screen of the monitor) as the boot process is proceeding.

The POST runs very quickly, and you will normally not even notice that it is happening.
unless it finds a problem. You may have encountered a PC that, when turned on, made
beeping sounds and then stopped without booting up. That is the POST telling you
something
is wrong with the machine. The speaker is used because this test happens so early on,
before
the video is activated! These beep patterns can be used to diagnose many hardware
problems

with the PC, The exact patterns depend on the maker of the BIOS; the most common are
Award and AMI BIOS.

BIOS Starting Screen

When the system BlOS starts up, you will see its familiar screen display, normally after the
video adapter displays its information. These are the contents of a typical BIOS start up

Screen:

The BIOS Manufacturer and Version Number.

The BIOS Date: The date of the BIOS can be important in helping you determine its
capabilities.

Setup Program Key: The key or keys to press to enter the BIOS setup program.
(This is usually {Del), sometimes (F2;. and sometimes another key combination.
System Logo: The logo of the BIOS company, or in some cases the PC maker or
motherboard manufacturer.

The "Energy Star" Logo: This distinctive logo is displayed if the BlOS supports the
Energy Star standard, which almost all newer ones do.

The BIOS Serial Number: This is normally located at the bottom of the screen.
Since BIOSes are highly customized to the particular motherboard, this serial number
can be used in many cases to determine the specific motherboard and BIOS version
you are using. Check out Wim Bervoets" BIOS site for a huge list of these numbers

Troubleshooting B1OS Beep Codes

When a problem is identified with the system during the POST, the BIOS will normally
produce an error message. However, in some cases the problem is detected so carly in the
test
that the BIOS cannot even access the video card to print the message! In this case the BIOS
will produce a beeping pattern on the speaker to tell you what the problem is.

The exact meaning of the beep codes depends on the type and version of BIOS that you
have.
The three most popular types of BIOS are those made by Award, American Megatrends
(AMI) and Phoenix. The beep codes for these BIOS products are described in this part of the
troubleshooter. If you are using a PC made by a company that writes its own BIOS, you will
have to consult your owner's manual
A single beep during the boot process, usually right before the BIOS startup screen is
displayed, is normal and does not indicate a failure as long as the boot continues on.

Beep codes can be in several different patterns, depending on the BIOS that you are using
Some BIOSes use very simple beep codes in a pattern of varying numbers of short beeps,
while others may mix short and long beeps. The Phoenix BIOS is famous for its complicated
beep patterns that are actually in up to four groups--one or more beeps and then a pause,
followed by as many as three more patterns.

Introduction to Troubleshooting

The problems that occur in a PC can be categorized mainly into two.

1.​ Problem of booting or starting up of the PC

2.​ Problem occurring after the boot up.

For successful troubleshooting, we must always gather some vital information as listed
below:

Description of the problem like what error message, unusual displays was seen before
the trouble

When did the problem start?

What was the situation when the problem started ?

What software or program was running when the problem occurred?

Was the computer moved in recent times?

Was there any electrical power (Mains) supply problem or a thunderstorm prior to the
trouble?

Were any hardware, software or configuration changes made in the computer?

Has someone else used the computer?

If the screen is blank and entire system is "dead" nor lights, no spinning drive or no fan, then
there
is obviously a power supply problem.

Troubleshooting the power supplv

First of all conduct a preliminary check as follows:

check for any burnt parts
Check all connections to the computer like the mains cord, monitor cord are loose and
ensure that they are well connected.

Check if the switches of UPS, Extension cords etc., are switched ON.

If the fan is not running, turn off the computer, open the case and check the
connections to the power supply.

In newer ATX power supplies, a wire runs from the power switch on the front of the
ATX case to the motherboard. Ensure that this wire is connected to the motherboard
and the switch turned on before the power comes up.

Check the output voltage from the power supply.

If there is no voltage from the power supply or if there is a low voltage, remove all
non essential cxpansion cards (modem, sound etc.,) and check the voltage. If there is
no voltage still then the power supply unit is faulty.

If the voltage is OK after all the cards are removed, Insert the cards one by one and
check the voltage. The voltage will fall or reduce when the defective card is inserted.
Using a soft brush clean the interiors of the case, slots ete., before putting the cover
back.

Trouble shooting of the Power supply unit

Some of the symptoms of the power supply failure in a PC are as follows:

The PC sometimes halts during booting and after several tries boots success fully.
Error codes or beep occur during booting but they come and go.

The computer hangs or stops for no reason. Sometimes it might even reboot itself.
Memory errors appear intermittently.
Data is written incorrectly to the hard disk.
The keyboard stops working at odd times.
The motherboard fails or is damaged.

The power supply overheats and will become too hot to touch.

Some remedial measures that can be carricd out are as follows:

An overheated system can cause intermittent problems. Use compressed air or an

antistatic vacuum to remove dust from the power supply and the vents over the entire
computer. Check the power supply fan and the fan over the CPU both work.

If a system is upgraded with additional drives and accessories, the power supply unit
may be operating above its rated capacity thus causing reboots and intermittent
otherwise unexplained errors⁹. Upgrade the power supply unit to withstand the
additional loads.
An electrical conditioner (Protective device like Surge suppressor) might solve the
problem of intermittent errors caused by noise in the power line connected to the PC.

Troubleshooting the power supply fan

An improperly working fan causes power supply problems. Usually before a an sops
working. it hums or whines, especially when the PC is first turned on. If this has just
happened , replace the fan or replace the power supply itself.

If the fan still does not work even after replacing the power supply then it is not the problem
with the fan A short somewhere else in the system and drawing too much power may be
causing the problem.

Do not operate the PC if the fan does not work. Computers without cooling fan can quickly
overheat and damage the chips. To troubleshoot a non functional fan, which might be a
symptom of another problem and not a problem of the fan itself, follow the steps:
1.​ Turn off the power and remove all power cord connections to all components,
including the connections to the motherboard and all the power cords to the drives.
Turn the power back on. If the fan works, the problem is with one of the systems that
was disconnected, not with the power supply or its fan.

2.​ Turn off the power and reconnect the power cords to the drives. If the fan comes on,
you can eliminate the drives as the problem. If the fan does not come on, then try
one drive at a time till the drive with a short is identified.

3.​ If the drives are not the problem, suspect the motherboard subsystem. With the
power off, reconnect all power cords to the drives
4.​ Turn off the power and remove the power to the motherboard by disconnecting P8
and P9 or P1. Turn back the power on.
5.​ If the fan works, the problem is probably not the power supply but a short in one of
the components powered by the power cords to the motherboard. The power to the
motherboard also powers interface cards.
6.​ Remove all interface cards and reconnect plugs to the motherboard.
7.​ If the fan still works, the problem is one of the interface cards. If the fan does not
work, the problem is the motherboard or something still connected to it.

Power problems with the motherboard

The motherboard, like all other components inside the computer case, should be grounded
to
the chassis. Look for a metal screw that grounds the board to the computer case. However,
a
short might be the problem with the electrical system if some component on the board
makes
an improper contact with the chassis. This short can seriously damage the motherboard
Check for missing standoff (small plastic spacers that hold the motherboard a short distance
away from the chassis), the problem that most often causes these improper connections.

Shorts in the circuits on the motherboard might also cause problems. Look for damage on
the
bottom of the motherboard. These circuits are coated with plastic, and quite often damage is
difficult to spot.

Frayed wires on cable connections can also cause shorts. Disconnect hard drive cables
connccted dircctly to the motherboard. Power up PS and P9 or Pl connected but all cables
disconnected from the motherboard. If the fan works, the problem is with one of the systems
you disconnected.

Overheating Issues

If your computer hangs after it has been running for a while, you may have an overheating
problem. First, check whether there is air flow within the case. Open the case and make sure
the CPU and the power supply fans are turning and that cables will not fall into the fans and
prevent them fromn turning when you close the case. While you have the case open, use an
antistatic vacuum designed to be used around electronic equipment or a can of compressed
air. To blow dust off the motherboard and the CPU heat sink. Check the vents of the case,
and clear any foreign material that may be blocking airflow.

After you close the case, leave your system off for a few hours. When you power up the
computer again, let it run for 10 minutes, go in CMOS setup, check the temperature reading,
and reboot. Next let your system run until it shuts down. Power it up again and check the
temperature in set up again. A significant diference in this reading and the first one you took
after running the computer for 10 minutes indicates an overheating problem. Try adding an
extra case fan or more powerful fans than those you already have. When adding extra fans,
for every fan that blows air out of the case, use one that blows air into the case. Also, you
can
monitor the temperature inside the case using a temperature sensor that sounds an alarm
when
a high temperature is reached or uses software to alert you of a problem.

Be careful when trying to solve an overheating problem Excessive heat itself may damage
the CPU and the motherboard, and the hard reboots necessary when your system hangs
may
damage the hard drive. If you suspect damaged components, try substituting comparable
components that you know are good.