COMPUTER HARDWARE REPAIRS AND MAINTENANCE
Objectives
Knowledge of Computer Hardware
Identify computer hardware Issues/Problems
Determine faulty Computer hardware
Know Basic computer troubleshooting tips
Knowledge of Operating System and device Drivers
Identify hardware Peripherals
Basic knowledge of safeguarding hardware
Apply the knowledge to repair/maintain a computer.
Learning the Computer Basics
What is a Computer?
• An electronic device, operating under the control of instructions stored in its own memory that can:
– Accept data (input)
– Process the data according to specified rules (process)
– Produce results (output)
– Store the results (storage) for future use.
Examples and type of computer
Computer System is functional only if:
Basic Hardware components
Hardware represents the physical and tangible components of a computer i.e. the components that can be seen and touched.
Examples of Hardware are following:
Input devices : Keyboard, Mouse etc.
Output devices : Printer, Monitor, Speaker etc.
Secondary storage devices : Hard disk, CD, DVD etc.
Internal components : CPU, Motherboard, RAM etc.
Hardware Components
SMPS (Switch Mode Power Supply)
SMPS is known as the power supply of the computer. It is the component which supplies power to every other part of the computer such as motherboard, optical drives, etc.
SMPS is a device which changes the AC power coming to our wall socket into DC so that our computers can use it. You must be thinking why is there a need for AC to DC conversion? Well, the wall sockets in our home have AC power supply of 230 volts. 230 volts is very high voltage which can damage our computer if we use it directly. So, the computer is built to work on DC (Direct current) which is of low voltage. So AC power from the wall socket has to be changed to DC power. The SMPS takes the AC power from the wall socket. Inside the SMPS the AC power is changed to DC power. This DC power is then supplied by the SMPS to different parts of the computer.
Types of SMPS
A computer cabinet has certain specific dimensions which matches the dimension of the motherboard and SMPS. This is called the form factor of the cabinet. The form factor of the SMPS must match the form factor of the cabinet, only then will the SMPS fit into the cabinet.
There are two most used SMPS depending on the computer cabinet:
AT Type SMPS
ATX Type SMPS
ATX Type SMPS
They are used in ATX ((Advance Technology Extended) cabinet. They are popularly used now days. The ATX type SMPS has 24 pins in the power connector. The ATX power supply produces three main DC outputs, +3.3 Volts, + 5Volts and + 12 Volts. The power supply has different colored wires ending into a single 24 pin connector. Each color represents a fixed voltage.
Orange having 3.3 volt
Yellow having +12 volt
Red having +5 volt
Blue having -12 volt
Black having ground
Violet and gray having 5 volt
Green is for power switch
AT Type SMPS
They are used in AT (Advance Technology) cabinet. They are now out of use but you may find it in some old computers. The AT type SMPS has 20 pins in the power connector.
Uninterrupted Power Supply (UPS)
UPS is a device which stores power. The UPS has an in-built battery cell. When AC power from the wall socket is available, the UPS converts this AC power to DC power and stores it. When AC power from the wall socket is not available, the UPS converts the stored DC power to AC power and provides it to the load for use.
AC Power from Wall Socket-> Stored in UPS as DC Power-> During Load Shedding DC is converted to AC -> AC Power Supplied to SMPS-> AC Power changed to DC by the SMPS -> DC Power Supplied to PC
What is Computer Ports?
Port Is a connector on the motherboard or on a separate adapter that allows a device to connect to a computer; these may include keyboard, mouse, serial, parallel, network, sound, or video ports.
Ports vary with the type of equipment that connects to the ports.
Ports have gradually changed over (me as computers have changed to become faster and easier to work with.
• D-shell connector – A connector with more pins or holes on the top row than on the bottom so that a connected cable can only be a]ached in one direction and not accidentally connected the wrong way; generally represented with the letters DB and the number of pins such as, DB-9, DB-15, or DB-25.
• DIN connector – Round with small holes and normally keyed; the keyboard and mouse are usually this type of connector with either 5 or 6 pins.
Arrangement of computer Components/ Ports
Computer Software
What is Software?
Software is a set of programs, which is designed to perform a well defined function. A Program is a sequence of instructions written to solve a particular problem.
Types of software
System Software
The system software is collection of programs designed to operate, control, and extend the processing capabilities of the computer itself.
System software is generally prepared by computer manufactures.
System software serves as the interface between hardware and the end users. E.g. Operating system, Compilers, Interpreter, Assemblers etc.
Application Software:
Application software products are designed to satisfy a particular need of a particular environment.
Application software may consist of a single program, such as a Microsoft’s notepad for writing and editing simple text.
It may also consist of a collection of programs, often called a software package, which work together to accomplish a task, such as a spreadsheet package. E.g. Payroll Software, Student Record Software , Inventory Management Software, Microsoft Office Suite Software, Adobe Premiere suites etc.
• Utility Software
Allow a computer to perform tasks that are not part of the operating system, but are still practical and useful. For example, utility software might instruct a computer on how to copy (burn) information to a CD-ROM disk, or it might be an antivirus program
Proprietary Software vs. Open Source Software
Examples and types of software
Relationship between Hardware and Software
Hardware and software are mutually dependent on each other. Both of them must work together to make a computer produce a useful output.
Software cannot be utilized without supporting hardware.
Hardware without set of programs to operate upon cannot be utilized and is useless.
To get a particular job done on the computer, relevant software should be loaded into the hardware. I.e. a device driver is needed.
Device driver is a program that controls a particular type of device that is attached to your computer. There are device drivers for printers, displays, CD-ROM readers, diskette drives etc. When you buy an operating system, many device drivers are built into the product.
Hardware is a one-time expense.
Software development is very expensive and is a continuing expense.
Different software applications can be loaded on hardware to run different jobs.
Software acts as an interface between the user and the hardware.
If Hardware is the 'heart' of a computer system, then Software is its 'soul'. Both are complimentary to each other.
Electric Safety
Electrostatic Discharge
Every matter or object contains some electric charge which is called Electro Static Charge. When two objects touch each other, these charges are exchanged. The PC has internal electronic parts. When another object or human being touches these parts, there is a flow of charges. This flow of unwanted charges is known as Electro Static Discharge (ESD). Electro static discharge can lead to an electric shock and can also damage the internal parts of the PC. Any part or equipment that is ESD sensitive has the following mark shown on it.
You must be thinking how electrostatic discharge can lead to an electric shock?
Conductors and Non Conductors
Conductors:
They are the materials which allow electric charges to flow through them easily. Examples of electric conductors are metal, water, etc. Such materials that allow electricity to pass through them are referred to as “good conductors” of electricity. The human body is a good conductor of electricity. It allows electric charge to follow through it easily. That is why you get a shock when you touch any live wire or running electric component.
Non Conductors:
They are the materials which do not allow electric charges to follow through them. Examples of non conductors are wood, rubber, plastic, etc. Such materials are referred to as “bad conductors” of electricity.
Electric wires have metallic copper wires inside for electricity to flow. But they are covered with a material that does not allow current to pass through it, thus making the wire safe to touch. Such a material that resists the flow of current is known as an insulator. Copper wires have an insulator covering them, thereby protecting us.
Earthing
All electric equipments use electrical power. The power is used such that the body of the equipment is not exposed to any current. This allows the user to safely touch the equipment body, even if it is metallic. However, if the internal electric wire of the equipment is faulty, then electricity may leak to the metallic body of the equipment. This can also lead to electric shocks as the leaked electricity will travel to the ground through your body.
To prevent the user from getting a shock due to leakage of electric current, electronic devices today are provided with earthing wires. The earthing wire connects the equipment body to the ground. So in case of fault, the leakage power will flow to the ground from the equipment via this wire and not through the user’s human body. In this way the user is protected from electrical shocks. Therefore, we must always use equipments with 3-pin plug as it has the earthing pin included.
3-pin Plug
The 3-pin plug offers maximum safety to the user as it diverts the leaked current towards the ground. This protects the user from electric shocks.
The 3 pins are connected as follows:
L or the Live pin, through which electricity enters the load
N or the Neutral pin, which is the return path for the electricity
E or Earthing pin, which diverts any leakage current to the ground
Safety Tips while working with Electricity
Take these precautions while working with electricity:
Do not touch any electric part with live current.
Wear rubber slippers to stop electricity flowing through your body to the earth.
Water is a conductor; hence never touch any electrical point with wet hands. Also, make sure electrical socket is not on a damp wall and that you do not stand on wet ground.
Close sockets when not in use.
Do not allow wires to run under a carpet, as you may not know of any damages happening under the carpet.
Do not insert more than one cable in a socket. It leads to the flow of more current and may generate a lot of heat which can damage the socket.
Attend to any loose wire immediately. Press the switch OFF button at once and remove the plug from the wall-socket immediately. Then tighten the loose wire to prevent any accident.
Do not insert wires inside a socket without the plug top. This is very dangerous as there is a chance of touching a live wire.
Earthing is a safety element for the user. Hence never replace a 3-pin plug with a 2-pin plug. Similarly, do not use a 3-pin plug in a 2-pin socket.
To avoid damage due to ESD, wear an Electro Static Discharge safety-band on the wrist while working. If this is not available, then keep yourself grounded by touching a metallic surface every few minutes during work.
Internal components of the PC are made up of electronics and are delicate. Do not touch them unnecessarily. They can get damaged due to electrostatic discharge.
Safety Precautions during Computer Assembly
Handle all parts gently and with care.
Handle components from the edges. Do not hold from the center.
Use antistatic wrist band and anti-static mat. If antistatic metal strap is not available, touch the ground after every few minutes and strictly handle components by the edges.
Place the components on an antistatic mat.
Work in a clear dry area with minimum dust and no dampness.
Turn off the power plug or wall outlet during installation of components.
Ensure that earthing is proper. Earthing protects the user from fatal voltages inside SMPS.
Beware of the sharp edges inside the cabinet.
Some cabinets have the metal burr or their edges are not smoothened.
Do not install or remove a component when in power ON condition as it may damage the component.
Do not open or touch components like hard disk drive, SMPS or monitor while the electric power is switched ON. These components may retain electrical charge even after switching OFF the power. Touching them may lead to a fatal electric shock.
Identifying Computer Problems/Issues
Hardware or Software Problem?
Tips for Distinguishing Between Hardware Problems and Software Problems…
Note: Make sure you reduce possible “external” problems before proceeding. This means unplug any external devices (such as hard drives, scanners or printers), and remove any USB Flash disk, CD or DVD disks from their drives.
Were there any loud noises or smoke when the problem first appeared? Then it is probably a hardware problem, with the most likely culprit being the SMPS (Switched Mode Power Supply ) unit.
Is the computer entirely dead? Or the screen blank? Or the screen showing a poor/incomplete picture? These faults are probably also due to hardware problems.
Does the computer produce a series of beeps? This is a code that can be used to distinguish some hardware problems.
Does the system give any error codes or descriptions while booting? These can be due to hardware or software problems. Take careful note of all information given in the error code.
Does the computer produce error information after it has booted or only when you open specific programs? These error codes are probably due to software problems.
Have any recent changes been made to hardware or software (including BIOS setting)? If so, these are likely culprits.
Has the computer been exposed to viruses or other malware? This could be a cause of software problems.
Use the Device Manager. The Device Manager will list all of the hardware devices installed on a PC. Any device with a problem will have a warning symbol next to it, and double clicking on that device would give details and suggested remedies for the problem.
Computer Maintenance
NOTE: Prevention (maintenance) is better than cure (Repairs).
Computer maintenance is necessary…
Check harmful materials e.g. dust, virus, outdated software, faulty electrical Power/ gadget e.g. cables, sockets, extensions etc.
Check any malfunctions of peripherals.
Proper maintenance helps to keep the computer running smoothly for years.
Caution!!!
These steps are for the experience and professionals only!!
Improving slow performance
Dust Control.
Dust is very harmful for computer parts.
Excess dust can cause mechanical failures, particularly on computer components with moving parts.
Computers should be dusted regularly by using compressed air machines.
As a hard disk becomes full, the computer’s performance is reduced.
It takes more time to find and access needed files.
Defragmentation is not as successful due to a lack of free space to temporarily move files to while they are being rearranged.
Therefore, it is wise for a computer user not to keep files that are no longer needed.
Files that have been stored in a user’s documents folder that are no longer needed (such as extra photos or older versions of documents) should be deleted.
A typical example of a fully loaded Local Hard Disk drive
Deleting Browsing History
The browser stores the recent history of the web pages that the user has viewed
This makes it easier to find and load these web pages again.
The browser also stores other small bits of information such as data entered into forms and usernames or passwords if a user has asked a web page to “remember me” (although this is not a good idea for shared computers).
This stored information can be easily deleted.
Startup folder
Some programs will automatically put a shortcut in the Startup folder, forcing the program to automatically launch when you turn the computer on or log in. Sometimes this is desirable, sometimes not. Either way, this practice may slow your computer down to various degrees, and with the program running all the (me, may slow down the performance of your computer.
Delete some of the programs in the Startup folder
Software Inventory
Once the hard disk becomes full, a computer’s performance is reduced. To avoid installing software that are not necessary, system inventory will require you knowing what software is needed/wanted on your computer.
Note:
Please use caution when uninstalling software. In order to reinstall, you will need the original software installation files
Protect your PC from cyber-threats or Malware
The cyber-world is full of threats such as viruses, spyware, Trojans, Worms and etc. These cyber-threats can cause huge dilemmas to your computer. These undesirable programs, which are usually added without a user’s knowledge, can significantly slow down the performance of a computer.
The best ways to prevent virus infections are:
Keeping antivirus software up to date and running scans on a regular basis
Strict policies should be put in place to prevent virus infection e.g. prohibiting the use of flash drives, or require Flash disk to be scanned before use.
Other policy to consider is the prohibition of downloading, since unsuspecting users can accidentally download malware.
A firewall may also be used to blocks dangerous downloads.
UPDATING SOFTWARE
It is important for a computer user to find and install software updates in order to have well performing computers.
Updating software can be done in a variety of ways, Automatic Updates, Automatic Alerts for Updates, Manual Updating, Offline Updating.
Overheating
Excessive heat can cause a significant decrease in computer performance.
In order to cool down an overheated computer processor, avoid operating the computer if the case is in an enclosed space. (Such as a drawer or cupboard).
Also cool the room with fans or air-conditioning.
Also verify that all of the fans in the computer case are functioning properly.
Note: Modern computers have safeguards that shut down the system if a component is overheating.
Insufficient RAM
Computer need sufficient RAM to perform the desired functions once the memory is not sufficient. The performance will be slow. This problem is most likely if the computer is rather old and has had a newer (and more memory demanding) operating system installed.
Endurance:
Lastly, one important hint to also keep in mind when you are using a computer is to be patient. Sometimes the computer has to “think” too!(process)
Note: Avoid opening too many programs at a (me. It will reduce the performance of the computer.
Hardware Repair
Repair means to rectify, to fix the problem either in the hardware or software. it may also include replacement of a component that is faulty.
It is an essential part of troubleshooting.
In finding or analyzing the faults, it can be decided which hardware or software can be repaired.
GENERAL GUIDELINES FOR REPAIRING COMPUTERS
For repairing or trouble-shooting a computer use the following guidelines:
Gather together your toolkit: e.g. air blowing machine, screw drivers, software, back up disk etc.
Check for power FIRST, before doing anything else. 10 - 15 percent of all computer Issues/Problems emanate from power surge. Check this BEFORE doing anything else. Check to be sure if the computer is plugged in to an AC outlet properly.
Check your external connections to the computer. Specifically, check the mouse, keyboard, monitor, modem and/or printer cables, making sure that all are secure and in the right sockets.
Perform the Power On Self Test (POST) is a set of procedures that a computer runs through each (me it is turned on. It ensures that all of the system's hardware is working properly before trying to load the operating system. If the computer does not pass POST, it will not boot.
Tip: Make sure the computer turns on. If nothing happens (no lights, no sound, no fans, etc.), the computer has a power related issue.
GENERAL GUIDELINES FOR REPAIRING COMPUTERS
If the computer is still malfunctioning, go ahead then and open the case.
Check to see that all of the cards are fully pressed down into the bus connections, that any socketed chips are fully pressed into their sockets, and that all cable connections are fully attached. Make sure that the drive cables are attached correctly.
Clean any dust or foreign material out of the case while it is open.
Dust can cause overheating problems and electrical shorts. Sometimes, insects will nest inside the case as well. All of this needs to be cleaned out before you close up the case. Take precautions to avoid inhaling excess dust, and consider using protective eyeware if necessary.
Try to boot the computer to the hard drive, or to a bootable CD/DVD disk if necessary.
Sometimes the hard disk will become corrupted by a user, or by a virus.
Check the CMOS setup program, and correct any configuration problems.
If the information in CMOS RAM about your PC's configuration has been changed, or if the battery has died, your computer will not boot correctly, or it will not recognize certain components.
Look for unwanted changes.
Someone may have turned the brightness down on a monitor, or the LAN staff may have changed your PC's configuration without your knowledge (or approval), or an installation program may have corrupted your software. Look for recent changes in your system's operation. You may need to run an uninstaller program to remedy software-related problems.
Isolate the problem to one piece of hardware, or one software package.
When all these fails, then consult a professional.
Computer issues/Problems and the tips to troubleshoot and fix/ repairs .
The computer is unable to start up
If the computer does not turn on when you press the power button, the following suggestions may help you to determine why the computer will not start up.
First of all, check if the computer is plugged in to an AC outlet properly. Plug another electrical device into the outlet to be sure that the outlet is providing adequate power. A surge protector can be used in this case, because voltage surges can be very damaging to computers and other electrical components. Then put on the system to perform a POST .
After the POST and it is confirms that, the computer is producing all of the usual startup sounds and lights, but the monitor is not displaying any information, perhaps there is a problem with the monitor. Make sure that it is connected to a power source, and also that the VGA cable is connected to the computer.
The computer screen is blank
If the screen is blank, the computer may not be set to display the image on the computer screen.
First, check if the monitor is plugged in to a power outlet and is connected to the computer securely and make sure the monitor power button is on.
If the power light is not on, it means that the outlet is not delivering power to the monitor. Fixing the power outlet in such cases should help solve the issue.
The Blue screen
These errors are often caused by
Poorly functioning device drivers,
Hardware problems (such as memory, power supplies or system overheating),
Problems with the system software.
The option of System recovery and backup service will restore your PC to an earlier point of stage. You can perform this action whilst you get a Blue screen error or sudden system crashes.
NOTE: Backup service is an assurance that your data is safe.
Trouble with video card
If the power light of the computer and monitor is on and nothing comes up on the screen when you start your computer then there must be something wrong with video card. Change its video or the graphics card with a new one.
OS or some Software is functioning abnormally – If the Operating System (OS) or some other software is unresponsive or responds abnormally,
Immediate Solution: Restart your computer and run a virus scan.
Note: You should have reliable antivirus software installed on the computer to fix this issue.
Windows do not boot properly – If windows do not boot properly then you should reinstall windows with the windows recovery disk. Most of the times, this should help you get rid of the problem.
The computer is on but not responding the computer is on but not responding to software or keyboard commands, then it must be frozen or halted.
Immediate solution:
Press and hold the power button for at least 5 seconds,
It will be turn off.
Now restart your computer. This should fix the problem.
An external device is not working – If an external device does not function as expected.
Immediate solution:
turn it on according to Manufacturers instruction;
be sure that all device connections are secure and receiving electrical power
Be sure the device is compatible with the operating system.
And that the correct drivers are installed and updated.
Most common Basic computer Hardware Repairs
Replacing a Power Supply. The power supply failure is a common problem in our country. This is due to an uneven or “poor” voltage and power surges.
• Replacing a Hard Drive or formatting and installing Fresh OPERATING SYSTEM.
• Replacing RAM. RAM can fail or can loose from its housing and need to be reseated. If a computer needs new or additional RAM, it is important to make sure that the RAM used is compatible with the computer system. RAM is very easily damaged by electrostatic charges, so it is very important for the user to be grounded before picking up RAM. Also RAM should only be handled by the edges.
Peripheral Hardware Use and Maintenance
Peripheral hardware will also last longer if it is well maintained. Peripheral hardware such as printers, scanners will last longer if proper care about heat, dust and power surge control is taking to consideration.
Troubleshooting and fixing Printer problems
Let’s assume that your printer’s drivers are up-to-date
and that it has enough paper and ink or toner to print.
Try turning the printer off and on.
Unplug the printer and plug it back in.
Check your printer’s print queue by looking for the printer icon in the system tray and double-clicking it.
The print queue shows you the status of each job as well as the general status of your printer.
make sure that ‘Use Printer Offline’ isn’t selected.
Ensure that ‘Use Printer Offline’ isn’t checked.
Sometimes, printing while your printer is turned off can cause Windows to set your printer to work offline, and that can stall jobs sent later.
MALWARE
Virus
Malicious software is any software used to disrupt computer or mobile operations, gather sensitive information, gain access to private computer systems, or display unwanted advertising. This malicious software finds its way into:
Boot sector
File Allocation Table
Partition table
.Com and .Exe. Files.
Deadly effect of virus
Delete files
Change files,
Steal important information,
load unwanted applications
Send documents via electronic mail (e-mail),
Cripple a machine’s Operating system (OS), the basic software that runs the computer.
Virus warning signs
The computer’s performance slows down considerably.
Programs don’t function as they should. They either don’t start, or if they start, they stop or do not give the desired output.
Computer fails to boot.
Files and folders keep disappearing without anybody deleting them.
The computer crashes or freezes indiscriminately such as program not responding errors.
The computer keeps showing out –of -memory space messages or strange dialog boxes.
Programs and windows popping up randomly.
Disk cannot be accessed
New icons and programs get installed automatically.
Printing doesn't work correctly
Windows shuts down or restarts unexpectedly.
A partition in the system disappears automatically.
File size changes for no apparent reason
An increase in the number of files on the system when nothing has been added.
A Good Virus Protection Program should:
Scan for viruses:
Should be able to check your drives for viruses, as well as the RAM of your computer, and detect the presence of a virus.
Clean up the virus:
Must be able to get rid of the virus it finds on your computer; otherwise, it is useless.
Protect your System from viruses:
Must have the ability to load a piece of the program into memory at boot-up time, to protect you from getting a virus in the first place.
Provide Automatic updates:
Must regularly and automatically check back with the manufacturer for information on new viruses,
CONCLUSION: Best Practices and Dos and Don’ts
Always ensure that the power has been turned off before installing or troubleshooting any hardware part of the computer.
Before opening a computer case, always unplug the power cord from your computer.
After unplugging the power cord from your case, hold the power button in for at least 5 seconds. This will drain any residual electricity from the power supply
Always ground yourself to the case frame while touching any inside components. This can be done by touching the case frame with your bare hand, or using a clamp-on grounding device made specifically for this purpose
Keep all liquids away.
Avoid installing components when the computer is in operation.
When installing any, peripheral or device, always read the installation instructions that come with the device. Never apply force to try and connect any plug/device.
When fitting/handling processor on motherboard always wear gloves
Always choose to shut down you computer by clicking shutdown. Avoid switching of the power directly from the main switch.
If electrical power is lost, switch off all computer devices from the mains to avoid any problems due to power surge.
Always “eject “USB devices from the operating system before disconnecting them.
Upgrade the anti-virus regularly.
Always use UPS (uninterruptible Power supply)-This will keep your computer from crashing during power outages, and will protect your computer from low and high voltage occurrences.
Uninstall software by
“Add / Remove Program” function in Control Panel
Uninstall function of applications
Back up data, if possible, before making changes.
Check to ensure that speakers is not muted through the Control Panel
Maintaining the Battery for your Laptop
Most laptop batteries will last at least four hours when fully charged. If not maintained, however, the battery will require charging more frequently. For maximum performance. Use the battery as your power source until the low battery warning emerges.
Using your laptop with the AC adapter plugged into an electrical outlet will overcharge the battery. Overcharging decreases the life of the battery. Eventually the battery will be unable to hold a charge and will require a replacement.
Condition the battery for maximum performance
1. Discharge the battery – use the battery until the low battery warning emerges.
2. Charge the battery – use the AC adapter until the battery is fully charged.
3. Then immediately disconnect the AC adapter from the notebook. The procedure above insures both maximum performance and long life for the battery
