UNIT-5

Introduction to Troubleshooting:
Troubleshooting is a systematic approach to solving a problem. The goal of troubleshooting
is to determine why something does not work as expected and explain how to resolve the
problem.

The first step in the troubleshooting process is to describe the problem completely. Problem
descriptions help you and IBM® Software Support know where to start to find the cause of
the problem. This step includes asking yourself basic questions:

 What are the symptoms of the problem?

 Where does the problem occur?
 When does the problem occur?
 Under which conditions does the problem occur?
 Can the problem be reproduced?

The answers to these questions typically lead to a good description of the problem, and that
is the best way to start down the path of problem resolution.

Computer Faults:
1. The Computer Won’t Start

A computer that suddenly shuts off or has difficulty starting up could have a failing power
supply. Check that the computer is plugged into the power point properly, if that doesn’t
work, test the power point with another working device to confirm whether or not there is
adequate power.

2. The Screen is Blank

If the computer is on but the screen is blank, there may be an issue with the connection
between the computer and the screen. First, check to see if the monitor is plugged into a
power point and that the connection between the monitor and computer hard drive is secure.
If the problem is on a laptop, then you may need to get a professional to fix it as some of the
internal wires may be worn.

3. Abnormally Functioning Operating System or Software

If the operating system or other software is either unresponsive or is acting up, then try
restarting your computer and run a virus scan. To avoid having this happen, install reliable
anti-virus software.

4. Windows Won’t Boot

 If you are having troubles booting Windows, then you may have to reinstall it with the
Windows recovery disk.

5. The Screen is Frozen

When your computer freezes, you may have no other option than to reboot and risk losing
any unsaved work. Freezes can be a sign of insufficient ram, registry conflicts, corrupt or
missing files, or spyware. Press and hold the power button until the computer turns off, then
restart it and get to work cleaning up the system so that it doesn’t freeze again.

6. Computer is Slow

If your computer is slower than normal, you can often fix the problem simply by cleaning
the hard disk of unwanted files. You can also install a firewall, anti-virus and anti-spyware
tools, and schedule regular registry scans. External hard drives are great storage solutions for
overtaxed CPU’s, and will help your computer run faster.

7. Strange Noises

A lot of noise coming from your computer is generally a sign of either hardware
malfunction or a noisy fan. Hard drives often make noise just before they fail, so you may
want to back up information just in case, and fans are very easy to replace.

8. Slow Internet

To improve your Internet browser performance, you need to clear cookies and Internet
temporary files frequently. In the Windows search bar, type ‘%temp%’ and hit enter to open
the temporary files folder.

9. Overheating

If a computer case lacks a sufficient cooling system, then the computer’s components may
start to generate excess heat during operation. To avoid your computer burning itself out, turn
it off and let it rest if it’s getting hot. Additionally, you can check the fan to make sure it’s
working properly.

10. Dropped Internet Connections

 Dropped Internet connections can be very frustrating. Often the problem is simple and may
be caused by a bad cable or phone line, which is easy to fix. More serious problems include
viruses, a bad network card or modem, or a problem with the driver.
Nature of Faults:
An error or failure. A software fault, also known as a "crash" or "abend," is when the
program directs the computer to go outside of its restricted memory boundary. A hardware
fault is a failure in one of the circuits.

There are three main types of faults:

o transient 
o intermittent
o permanent.

Transient 

A transient fault is a fault that happens once, and then doesn’t ever happen again. For example, a
fault in the network might result in a request that is being sent from one node to another to time out
or fail. However, if the same request is made between the two nodes again and succeeds, that fault
has disappeared, which is how we can define it as transient.

Intermittent:
 An intermittent fault is one that occurs once, seems to go away, and then occurs again!

Intermittent faults are some of the hardest ones to debug and deal with, since they masquerade

as transient faults at first, but then come back — sometimes with inconsistency. A good

example of this is with loose connections in hardware, where sometimes it seems like the

connection works, but occasionally (and often erratically) the connection just stops working

for a bit.

Transient, intermittent, and permanent faults, visualized.

Permanent:

Finally, a permanent fault is one that just does not go away after it first occurs. A

permanent fault occurs once, and then continues to persist until it has been addressed. For

example, if part of a system runs out of memory, hits an infinite loop, or crashes unexpectedly,

that “broken” state will just continue to be the same until someone (or some part of the

system) fixes it or replaces it entirely.

The two main “flavors” of faults.
Last but not least, each of these three types of faults come in two flavors! And this is where

faults become even more tricky. Every transient, intermittent, or permanent fault runs the risk

of either being a fail-silent fault or a Byzantine fault.

A fail-silent fault (also sometimes called a fail-stop fault) is one where the node where the

fault originated actually stops working. In this specific flavor of fault, when the origin node

stops working, it will either produce no result (error/output) whatsoever, or it will produce

some sort of output that indicates that the node actually failed. In a fail-silent fault, there is no

guarantee that the node with the fault will actually give us an error, so it’s possible that we

won’t even know that a fault occurred!

By contrast, in a Byzantine fault, the origin node does actually produce an error output, but it

doesn’t always produce the same error output. And, confusingly, even though the node is

producing errors, it continues to run! In a Byzantine fault, a node could behave inconsistently

in the exact errors that it surfaces, which means that a single fault within a node could actually

result in the node responding with various different errors, all of them potentially different

from one another!

As we might be able to imagine, both a fail-safe fault and a Byzantine fault seem like

treacherous scenarios. And our systems should aim to try to build for those situations

(although, it’s important to note that we can’t build completely fault-free, fault-tolerant

systems…though it’s nice to try to strive in that direction). Faults are a cornerstone of key

distributed systems discussions, specifically because they are hard to deal with, reason about,

and consider while building our systems. But now that we know how to talk about them, what

they’re call, and what they might look like, we’re far more equipped than before to take these

crafty creatures on whenever we encounter them next in the distributed system wilderness!
Resources:

Faults are a big topic in distributed system, specifically because many folks have written about

how to understand and design for fault-tolerance in a system. There’s a lot of good content out

there on faults and how they fit into the larger narrative of distributed systems, but the

resources below are some of my favorites.

Fault Elimination Process:

10 Common PC Problems And Solutions:

1. Computer won’t turn on

This is probably the no.1 problem faced by many of us. To understand this problem, you can

compare it to our human body.When we are sick, we often get a fever. It’s the body

mechanism to fight infection. In the same way, when the computer faces any problem, it

usually won’t turn on until you fix that.

There are hundreds of reasons why a PC won’t boot up. The issues can range from power

supply failure to virus infection. Normally, by following the steps given below, your computer

should be able to start.

Solutions:

1. Check the power supply

If it’s a laptop, a loss of power could result from a battery that has completely run out of

charge. So, the first thing to do is to plug it in and leave it to charge for a few hours. If that

doesn’t work, it could mean the charger is faulty, so, if you can try a different charger. If the

charger has a power indicator, check whether it lights up when you plug it in.

If your PC is a desktop computer and doesn’t start, check that it’s not the plug socket at fault

by plugging it into a different socket. If that doesn’t work, it could be that the power supply in

your PC has failed.

2. Make sure the monitor or display is functional

If you can see that your PC has power, because the fans start-up or the power lights come on,

but nothing else happens, there are a couple of possible faults.

If you have a desktop PC connected to an external monitor, it could be the display that’s

faulty. Check the power connection to the monitor and that it’s properly connected to your PC.

Try disconnecting it and reconnecting it. If that doesn’t work, try connecting a different

monitor, if possible. That way you’ll be able to either determine it’s the monitor’s fault or rule

it out.

If you have a laptop, or if you’ve ruled out the external display, it could be that your PC is in

sleep mode and is having trouble waking. To check that, shut it down completely and restart

from cold. To do that, hold down the power button for 5 seconds and then press it again to

start your PC.

3. Eliminate external hardware

If none of the steps above work, the peripherals could be the culprit. This could either happen

because of electrical issues or external hardware failures.After doing this, try restarting the

system again to see if it works or not. If it doesn’t, move on the next final step.

4. Reinstall system

If none of the steps work, the last thing you would want to do is to reinstall your Windows.

Because till this point, you can be sure that it’s the software and not a hardware issue.

Since you can’t turn your computer on, there’s no way to get access to your file. However,

there are methods to backup your files from the hard drive. A clean installation will help to

reset everything back to normal, should your system is infected or corrupted.

2. Slow Internet
Nothing can be more frustrated than a slow internet connection. I know, you can’t enjoy that

famous Netflix show or stay connected on Facebook.But this problem is usually pretty easy to

deal with. The problem lies in 2 areas, i.e. internal issue ( issues related to your internet

appliance) and external ( related to your Internet Service Provider )

Solutions:

1. Restart the modem

This solution is just like how you would resolve any gadgets. Sometimes a power fluctuation

or overused of the internet modem can overload it.In order to reset everything back to normal,

simply switch off the modem, wait for few minutes and turn it back on. You should be good to

go in most cases.

2. Fix your wifi signal

Speaking of wifi, you might find that your router and internet are fine, but your wireless signal

is weak. This can cause a slowdown—or, at minimum, a latency-filled browsing experience.

In that case, you may need to reposition, tweak, and boost your router with a few tricks.Check

out this link here to find out how to fix your wifi signal with some good tips.

3. Kill any unwanted background software

Sometimes, background processes like software updates or any other programs that require

internet maybe pulling your data, hence slow down your internet speed.

By simply check your task manager, you can see the list of this software and are able to kill

them off. Turn off any automatic updates in the setting and this should help.

4. Contact your ISP

If none of the above works, your problem is maybe an external issue, i.e. from your internet

service provider.This could be something like a network upgrade, bad weather, wires fixing,
etc. Definitely, they will assess your internet signal and inform you of the necessary action to

take.

3. PC Becoming Slow

I know that kind of feeling you feel when it takes like 5 minutes to open just an app. Well, this

is another common computer problems people face in their daily lives.The root cause is

usually due to the duration of how long you have been operating the PC. A computer that is

older than 2 years will experience this, regardless of their specifications.

Solutions:

1. Find resource-hungry program

With your system full of programs, there will definitely be one or two programs that use lots

of your resources, for instance, a ram.To find out, open the Task Manager. You can right-click

your taskbar and select the “Task Manager” option or press Ctrl+Shift+Escape to open it. On

Windows 8, 8.1, and 10.

Click the “CPU,” “Memory,” and “Disk” headers to sort the list by the applications using the

most resources. If any application is using too many resources, you might want to close it
normally — if you can’t, select it here and click “End Task” to force it to close.

2. Disable startup program

Autostart programs during system startup can be the major reason why your PC is slowing

down.On Windows 8, 8.1, and 10, there’s now a startup manager in the Task Manager you can

use to manage your startup programs.Right-click the taskbar and select “Task Manager” or

press Ctrl+Shift+Escape to launch it. Click over to the Startup tab and disable startup
applications you don’t need.Windows will helpfully tell you which applications slow down

your startup process the most.

3. Scan for malware and adware

Day-to-day usage of computers can make you accidentally catch malware and adware.These

are usually small malicious programs, caught from the internet when we browse or download

something.These programs are designed to steal your information and to that, they have to

transfer information over the internet, which can potentially slow down your system.To

remove them, simply use your built-in anti-virus software to scan and detect. For more

information on how to remove spyware and adware, check out my article here.

4. Windows Update Problem

Windows update errors can occur due to a bunch of reasons. Causes include Windows piracy,

core files missing, license issues, etc.The problem is, however, not that serious. But if you still

want to have the latest software and security installed, you have to fix it.

Solutions:

The solution is quite straight forward. With an in-built error detection and troubleshooting,
Windows has its own mechanism to fix this.But if you still cannot fix it, I recommend going

through the official Microsft Windows update errors fixing walkthrough here.

5. Noisy Hard Drive

Hard drives are usually nearly silent but some do make a muted clicking sound when they’re

being accessed or turned off — this is completely normal.On the other hand, if you start

hearing noises only occasionally or noises that you’ve never heard before — like clicking,

grinding, vibrations, or squealing — your hard drive may be failing.

Solutions:

1. Make sure the sound comes from the hard drive

Usually, when we hear the sound from our computers, it’s a hard drive sound. So when the

sound suddenly gets louder, we assume that it’s from the hard drive.To check this, you can

simply unplug the power and data cables from the hard drive and reboot the system. If you still

hear the sound, the issue is not with the hard drive.

2. Run a diagnostic software

If you’re certain that the sound comes from the hard drive itself, you can run a free hardware

diagnostic software which is already available on many computers or available on the internet.

3. Replace the hard drive

If the diagnostic software fails, it simply means there is an issue related to the hardware of the

drive. If in that case, there is nothing you can do except to replace it.Remember to make a

back up of your files before replacing it.

6. PC Fan Not Working

Another common computer hardware problem here. However, people usually get panic when

the fan stops working.In reality, that it is normal behavior for the CPU fan to stop spinning

when the CPU temperatures are low or you are not running any power-hungry applications.In

most cases, it’s happening due to the motherboard, and not the fan itself.

Solution:

1. Determine the root cause

As mentioned, the motherboard is usually the main reason why the fan stops spinning. This

could happen because the fan isn’t installed well on the board or there’s a problem on the

board wires.To check this, simply connect the fan to the external power source and see if it’s

still working. If not, then the problem is with the fan itself.

2. Assess the fan

Three common issues related to the fan are:

CPU Fan Save Dusts

The Bearing of the CPU Fan is Stuck

CPU Fan is Broken

For the first case, you can simply clean it with a cloth. For the second and third cases, which

are the more serious case here, you need to hire professional computer repair service to replace

the part.

7. Printer Isn’t Printing

There are many reasons why your printer won’t print, so start with the basics such as checking

to see whether there is an error message or warning light on the printer.Make sure there is

paper in the tray(s), check the ink or toner cartridges aren’t empty, the USB cable is plugged

in or the printer is connected to Wi-Fi.The solution provided below will help you solve most

of the underlying issues.

Solution:

1. Restart the printer

By simply cancel all the active printing work and restart the printer can do many wonders.This

is because the printer might be overloaded or the new ink cartridges are being installed. So to

get the things in place, simply restart the device.

2. Check for issues on the computer

Every printer has its own driver and is connected to the computer. So should there be any

issues related to it, the system will display that, along with the device troubleshooting

mode.Mostly things can be fixed at this point. Make sure your printer driver is up to date and

is functioning normally.

8. Blue Screen Of Death (BSOD)

A Blue Screen of Death (BSoD) — also referred to as “blue screen,” “stop error,” or just

“system crash” — will happen after a critical error that the system is unable to process and

repair automatically.Usually, you may see a blue screen while upgrading to a new version of

Windows, during startup, or suddenly while actively using the computer, and the most

frustrating thing is that it’s just a screen with a blue background and a sad character face

without enough information to figure out the problem.

Solutions:

1. Check that there is enough space for updates

2. BSOD is usually a problem occurring due to corrupted files, file system failures and

system spaces.

Sometimes, your system space may get filled during the update, causing some of the files to be

missing, hence resulted in a corrupted file.

2. Scan your system for viruses

Some viruses can cause a Blue Screen of Death, especially ones that infect the master boot

record (MBR) or boot sector.

3. Update your hardware drivers

Most Blue Screens of Death are hardware or driver related, so updated drivers could fix the

cause of the STOP error.

4. Return BIOS settings to their default levels.

An overclocked or misconfigured BIOS can cause all sorts of random issues, including

BSODs.

5. Perform diagnostic tests on all hardware you’re able to test

It’s highly likely that the root cause of any given Blue Screen of Death is a failing piece of

hardware

9. Computer Freezes

A slow or aged computer can freeze from time to time. The main reason behind this is due to

lack of enough resources.Before regularly encounter this problem, your Windows should start

becoming slow first. To fix that, you can read the above point.

10. System Automatically Restart

Last but not least for common computer problems here, and quite the most frustrated one

too!.There are many reasons for this problem. It can be a result of various issues, including

corrupted drivers, faulty hardware, and malware infection, among others.It can be difficult to

pinpoint exactly what keeps your computer in a reboot loop. In most cases, it usually happens

after the Windows update.

Solutions:

1. Deleting bad registry files

Before you do this, you have to be completely confident that you can complete the process

without making any mistake.Keep in mind that the Windows Registry is a sensitive database.

Even misplacing a comma can cause damages to your computer! As such, I suggest you opt

for a one-click solution like Auslogics Registry Cleaner.This freeware automatically searches

for duplicate or corrupted registry files.

2. Updating drivers

When your drivers are outdated, it is possible for your computer to get stuck in a reboot loop.

This is because your devices are not able to properly communicate with your system.As such,

it is important to check if your drivers are up to date

3. Checking hardware issues

In some cases, a computer may keep on restarting because of faulty hardware. The three main

hardware to check on are:

1.RAM 2.CPU 3.External Devices

4. Scanning for viruses or malware

It is possible that your computer has been infected by a virus or malware – that is why it keeps

on restarting. You can run a complete virus scan by using Windows Defender.

Systematic Troubleshooting:
Motherboard Troubleshooting:
Common symptoms of motherboard issues are similar to CPU problems: The system
does not display anything; an error code appears; one or more beeps occur; the system locks;
the system reboots; a Windows BSOD (blue screen of death) appears; or one or more of the
ports, expansion slots, or memory modules fails.
 Motherboard problems and power problems are probably the most difficult issues to
troubleshoot. Because various components are located on the motherboard, many things can
cause errors. POST (power-on self-test) is one of the most beneficial aids for troubleshooting
a motherboard. The meaning of any codes that appear on the screen should be researched. If
multiple POST error codes appear, you should troubleshoot them in the order they are
presented.

The following list helps with motherboard troubleshooting:

 Is the motherboard receiving power? Check the power supply to see if the fan is
turning. If the CPU or motherboard has a fan, see if it is turning. Check voltages going
from the power supply to the motherboard. See Chapter 5 for directions.
 Check the BIOS/UEFI settings (covered in Chapter 4) for accuracy.
 Check for overheating. Power down the computer and allow the computer to cool.
Power on the computer with the cover off.
 Check the motherboard for distended capacitors. These are small components that
might appear to be bulging. If sighted, replace the motherboard as soon as possible.
 Reseat the CPU, adapters, and memory chips.
 Remove unnecessary adapters and devices and boot the computer.
 Plug the computer into a different power outlet and circuit, if possible.
 Check to determine whether the motherboard is shorting out on the frame.
 Check the CMOS battery (see Chapter 5 for how to take voltage readings).
 With a motherboard that has diagnostic LEDs, check the output for any error code.
Refer to the motherboard documentation or online documentation for the problem and
possible solution.

Floppy-disk controller:
A floppy-disk controller (FDC) is a special-purpose chip and associated disk
controller circuitry that directs and controls reading from and writing to a computer's floppy
disk drive (FDD). This article contains concepts common to FDCs based on the NEC
µPD765 and Intel 8272A or 82072A and their descendants, as used in the IBM PC and
compatibles from the 1980s and 1990s. The concepts may or may not be applicable to, or
illustrative of, other controllers or architectures.

Troubleshooting Floppy Disk Drives

Typical symptoms associated with floppy disk drive (FDD) failures during bootup include the
following:

 FDD error messages are encountered during the bootup process.

 An IBM-compatible 6xx (such as, 601) error code is displayed.
  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 the following:

 Disk Drive Read/Write/Seek error messages appear.

 The No Boot Record Found message appears, indicating that the system files in the
disk's boot sector are missing or have become corrupt.
 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.

A number of things can cause improper floppy disk drive operation or 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.

Basic FDD Checks:

If there is a problem booting the system, insert the bootable floppy disk in the new A
drive and turn on the system. If the system does not boot up to the floppy, examine the
advanced CMOS setup to check the system's boot order. It might be set so that the FDD is
never examined during the bootup sequence.

If the system still does not boot from the floppy, check the disk drive cables for proper
connection at both ends. In many systems, the pin-1 designation is difficult to see. Reversing
the signal cable causes the FDD activity light to stay on continuously. The reversed signal
cable also erases the Master Boot Record (MBR) from the disk, making it nonbootable.
Because this is a real possibility, you should always use an expendable backup copy of the
boot disk for troubleshooting FDD problems.

NOTE

If the system has a second floppy disk drive, turn it off and exchange the drive's connection
to the signal cable so that it becomes the A drive. Try to reboot the system using this other
floppy disk drive as the A drive.
If there is a problem reading or writing to a particular disk, try the floppy disk in a different
computer to determine whether it works in that machine. If not, there is most likely a problem
with the format of the disk or the files on the disk. In the case of writing to the disk, you
could be dealing with a write-protected disk, but the system normally informs you of this
when you attempt to write to it. However, if the other computer can read and write to the
disk, you must troubleshoot the floppy drive hardware.

Hardware troubleshooting for floppy disk drives primarily involves exchanging the FDD unit
for another one that is working. If necessary, exchange the signal cable with a known-good
one. The only other option with most PC-compatible systems is to exchange the system board
with a known-good one.

Hard Disk Controller (HDC):

A hard disk controller (HDC) is an electrical component within a computer hard disk that
enables the processor or CPU to access, read, write, delete and modify data to and from the
hard disk. Essentially, an HDC allows the computer or its processor to control the hard disk.

Troubleshooting Hard Disk Drives

Typical symptoms associated with hard disk drive failures include the following:

 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 bootup.
 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 hard disk drive (HDD) are missing or have
become corrupt.
 The computer does not boot up when turned on.
 An IBM-compatible 17xx error code is produced on the display.
 No motor sounds are produced by the HDD while the computer is running. (In
desktop units, the HDD should generally always run when power is applied to the
system—however, this does not apply to all desktops or portables when advanced
power-saving features are used.)
 A HDD Controller Failure message appears, indicating a failure to verify hard disk
setup by system configuration file error.
 A C: or D: Fixed Disk Drive error message appears, indicating a hard disk CMOS
setup failure.
 An Invalid Media Type message appears, indicating the controller cannot find a
recognizable track/sector pattern on the drive.
  A No Boot Record Found, a Nonsystem Disk or Disk Error, or an Invalid System
Disk message appears, 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 bootup
occurs, indicating that the HDD's CMOS configuration information is incorrect.
 An Out of Disk Space message appears, indicating that the amount of space on the
disk is insufficient to carry out the desired operation.
 A Missing Operating System or a Hard Drive Boot Failure message appears,
indicating that the disk's MBR is missing or has become corrupt.
 A Current Drive No Longer Valid message appears, indicating that the HDD's CMOS
configuration information is incorrect or has become corrupt.

HDD Configuration Checks

While booting up the system, observe the BIOS's HDD type information displayed on the
monitor. Note the type of HDD that the BIOS recognizes as being installed in the system.
Possible error messages associated with HDD configuration problems include the Drive
Mismatch Error message and the Invalid Media Type message.

Check the drive to ensure that it is properly terminated. Every drive type requires a
termination block somewhere in the interface. For Integrated Drive Electronics (IDE) drives,
check the Master/Slave jumper setting to ensure it is set properly for the drive's logical
position in the system. Remember that there can only be one master drive selection on each
IDE channel. If both drives share an interface and are set to the same selection, neither drive
should work.

If you have more than one device attached to a single interface cable, be certain that they are
of the same type (for example, all are Enhanced Integrated Drive Electronics [EIDE] devices
or all are ATA100 devices). Mixing IDE device types creates a situation in which the system
cannot provide the different types of control information each device needs. The drives are
incompatible and you might not be able to access either device.

If the drive is a SCSI drive, check to see that its ID has been set correctly and that the SCSI
chain has been terminated correctly. Either of these errors results in the system not being able
to see the drive. Check the CMOS setup utility to ensure that SCSI support has been enabled
along with large SCSI drive support.

Cathode-Ray Tube:
A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, the
beams of which are manipulated to display images on a phosphorescent screen.[2] The images
may represent electrical waveforms (oscilloscope), pictures (television set, computer
monitor), radar targets, or other phenomena. A CRT on a television set is commonly called
a picture tube. CRTs have also been used as memory devices, in which case the screen is not
intended to be visible to an observer.

Here are some common CRT problems:

CRT displays no image

Check the obvious things first. Verify that the CRT is plugged in (and that the receptacle has
power), the video cable is connected to the video card, the computer and CRT are turned on,
and the brightness and contrast settings are set to the middle of their range. If none of these
steps solves the problem, your CRT, video card, or video cable may be bad. Check the
suspect CRT on a known-good system or a known-good CRT on the problem system.

CRTs contain multiple filaments, which can be broken, or gas may have leaked into the
vacuum inside the CRT. CRTs damaged this way are unrepairable without specialist
equipment. With the display open. check if all three filaments are glowing bright orange.
Excessive redness or purple arcing signifies gas has leaked in. There may also be an internal
short inside the CRT, which is also unfixable without specialist equipment.

CRT displays only a thin horizontal line or a pinpoint at the center.The horizontal and/or
vertical deflection system has failed. The CRT tube itself is fine, but the circuitry driving the
tube has failed. Replace the display.CRT flashes one color intermittently, even when the
screen is blanked

This is a hardware problem with one of the electron guns. Replace the CRT. This problem
may also manifest as a strong color cast during normal operation that is not correctable using
the normal color balance controls.

CRT snaps, crackles, or pops when powered up, or emits a strong electrical odorCatastrophic
CRT failure is imminent. The noises are caused by high-voltage arcing, and the smell is
caused by burning insulation. Unplug the CRT from the wall before it catches fire, literally.

CRT emits a very high-pitched squeal.There are two likely causes. First, you may be driving
the CRT beyond its design limits. Some CRTs display a usable image at resolutions and/or
refresh rates higher than they are designed to use, but under such abuse the expected life of
the CRT is shortened dramatically, perhaps to minutes. To correct this problem, change video
settings to values that are within the CRT's design specifications. Second, the power
receptacle may be supplying voltage lower than the CRT requires. To correct this problem,
connect the CRT to a different circuit or to a UPS or power conditioner that supplies standard
voltage regardless of input voltage.

CRT displays some colors incorrectly or not at all.This is usually a minor hardware problem.
The most likely cause is that the signal cable is not connected tightly to the CRT and/or video
card, causing some pins to make contact intermittently or not at all. Verify that no pins are
loose, bent, or missing on the cable or the connectors on the CRT and video card, and then
tighten the cable at both ends, If that doesn't fix the problem, open the computer, remove the
video card, and reseat it fully.
In elderly systems, another possible cause is that some hardware DVD decoder cards "steal"
one color (usually magenta) and use it to map the DVD video signal onto the standard video
signal. Remove the DVD decoder card. If your video adapter includes hardware DVD
support, or if you are upgrading to such an adapter, you don't need a DVD decoder card.

This is also a symptom of a weak CRT, in which case the display should be replaced.Image
rolls or a horizontal line scrolls constantly down the screen.The most likely cause is that the
CRT is receiving inadequate power. Connect it to a different circuit or to a backup power
supply that provides correct voltage regardless of fluctuations in mains voltage.The
horizontal or vertical deflection system may also have failed, in which case the display
should be replaced.

Image flickers:
The most likely cause is that the refresh rate is set too low. Change the refresh rate to at
least 75 Hz. Flicker also results from interaction with fluorescent lights, which operate on 60
Hz AC and can heterodyne visually with the CRT. This can occur at 60 Hz (which is far too
low a refresh rate anyway), but can also occur at 120 Hz. If you're running at 120 Hz refresh
and experience flicker, either use incandescent lighting or reset the refresh rate to something
other than 120 Hz.