1. Facilitator: Suleiman Mohammed, citp(mcpn, mncs)
Lecture slides on: Installation, Repair, Servicing & Computer Maintenance concepts
Facilitator: Suleiman Mohammed, citp(mcpn, mncs)
Institute of Computing & ICT, Ahmadu Bello University, Zaria.

2. The Concepts
The effective & efficient working of a system depends on the following four features:
Maintenance
Servicing
Trouble shooting
Repair

3. Maintenance Maintenance includes both hardware & software in it.
Maintenance is a continuous process.
Hardware maintenance includes cleaning dust, maintaining constant voltage, etc.
Software maintenance includes reinstallation, upgradation & removal of different softwares.

4. Servicing Servicing is mainly associated with hardware equipment.
Servicing includes checkups, repairs and updation of all physical components.
Service provider should have proper knowledge about various components and their installation procedures.

5. Servicing steps
Uninstall all physical components starting from power connections to internal motherboard connections.
Clean dust from the components.
Perform a visual check or electronic check as required.
Reinstall all components carefully and properly.

6. Servicing steps Check for loose wiring or crack cables.
Check if any jumper is missing, if required replace it with a new one.
Check for physical damages of peripherals and replace them if needed.
Tighten all external connections.
Switch on the power supply and observe.

7. Troubleshooting
The detection and removal of faults in the computer system is known as troubleshooting.
If a problem is detected in a system, it is to be sorted out immediately.
Troubleshooting is of two types :
Hardware troubleshooting.
Software troubleshooting.

8. …troubleshooting
Troubleshooting depends on the following four factors:
Problem solving approach.
Techniques adopted in troubleshooting.
Tools and test equipments used.
Diagnostic aids in the PC.

9. Repairing Concepts
Repairing means to rectify the problem in the hardware or software. While finding or analyzing the faults, it can be decided which hardware or software can be repaired. Repairing may also include replacement of a component. It is an essential part of troubleshooting.

10. Repair Maintenance policy
Repair of components may result into adding up of cost and delay in operations.
Some failures occur because of repairs, it is called repair generated failures.
Repairs are termed as corrective maintenance.
Corrective maintenance is done when a fault occurs.

11. Repair Maintenance policy
Preventive maintenance should be favoured over corrective maintenance.
Preventive maintenance may add to the cost but saves operation time.
Preventive maintenance is often neglected and the emphasis is on repair maintenance policy.
It enforces maintenance through servicing.

12. Repair generated failures
These failures depend on the performance of the technician.
The technician during repairing process may leave some loose connections, wrong connections or some broken pins / broken wires.
These can be avoided if the technician rechecks/revise the work done.

13. Maintenance
Maintenance is a process which starts with installation of the system and runs through out the life of it.
Maintenance includes both…
Hardware maintenance.
Software maintenance.

14. Software Maintenance Adaptive maintenance Prefective maintenance
Software maintenance includes updation, enhancements, changes, repair and replacements.
Altered environment or changed conditions may result in software maintenance.
It is of the following two types :
Adaptive maintenance
Prefective maintenance

15. Hardware Maintenance
It includes proper cleaning, servicing, repairing or replacing components of the computer.
The following are the two types of maintenance methods used to keep the hardware intact :
Preventive maintenance.
Corrective maintenance.

16. Preventive Maintenance
Preventive maintenance means maintenance through preventions.
Careful handling of the computer enhances the life of the system and is called preventive maintenance.
Preventive maintenance can be done by taking some general precautions and some special precautions.

17. General Precautions
Ensure all peripherals are switched off before the main power is switched off.
Remove all CD’s from the drives before switching off the system.
Do not switch off the system when activity LED in hard disk drive glows.
Store CDs in clean and cool place where electromagnetic interference is absent.

18. …General Precautions
Do not obstruct air circulation to the computer site.
Do not eat or drink while working on the computer system.
When not in use, use dust covers for monitor, printer, etc.
Do not bend or scratch on CDs.

19. Special Precautions Do not apply force on key switches.
Do not rest hands on the keyboard.
Do not play with the keyboard after switching off the power.
Cable at keyboard end should not be subjected to high stress.
Do not use rough materials to clean the components of the system.

20. …Special Precautions
Use quality ribbon or ink to avoid damage to print head.
The internal parts of printer like stepper motor, print head, etc. should be cleaned properly periodically.
Switch off power before plugging and removing a cable, or inserting and removing a PCB.

21. Preventive Maintenance
The position where the system is kept should be dry and away from direct sunlight or rain.
Ensure the hard disk is backed up properly.
Remove dust from circuit boards using air blower.
Run the diagnostic softwares periodically.

22. Corrective Maintenance
It refers to the maintenance procedures that are adopted when any error occurs in the system.
It is contrary to preventive maintenance.
It starts when a failure or crash occurs in the system.
It includes repair and troubleshooting techniques.

23. Corrective maintenance steps
In case of failure general troubleshooting concepts should be performed first.
If problem remains, locate the fault using different tools or diagnostic softwares.
Once fault is determined, troubleshoot or replace the component, as required.
Corrective maintenance also includes periodic enhancements.

24. Corrective maintenance tools
Various tools that can be used during corrective maintenance are Data recovery tools from operating system, third party data recovery tools, virus vaccines, etc.
Though preventive maintenance is better yet there are times that corrective maintenance is used due to unseen factors leading to sudden failures.

25. Performance affecting factors
The factors affecting the performance of a computer are:
Heat & Humidity
Magnetism
Stray Electromagnetism
Power Surges
Corrosion & Rough Handling

26. Heat & Humidity
Excessive heat and thermal shocks are one of the major factors that effect the performance of the system.
More than half of the power given is wasted as heat and heat destroys the chip
To reduce the heat effect, a fan is installed with the power supply.
The room can be air conditioned.

27. …Heat & Humidity
Rapid changes in the temperature result in Thermal Shocks.
Humidity depends on the climate of the place.
It causes short circuiting inside the system and decreases the life of the system.
This factor can be foreseen and air conditioning can be installed as a remedy.

28. Magnetism
Magnetism may cause permanent loss of data on hard disk or CD.
It is mostly produced by electric motors or electric appliances.
Magnetic fields badly effect the data recorded on diskettes and CDs.
Precautions should be taken while preserving CDs & diskettes.

29. Stray Electromagnetism
Stray Electromagnetism includes electromagnetism interference, noise, interference, static electricity, etc.
Electromagnetism interference includes cross-talk and radio frequency interference(RFI).
Shielding and isolating system power from other loads is a preventive measure.

30. Power Surge Power surge or fluctuation is a source of lot of problems.
It causes unreliable operation and damages electronic components.
As their bad effects are known in advance, preventive measures should be taken.
Use of uninterrupted power supply (UPS) is a way to safeguard the system.

31. Corrosion & Rough Handling
Corrosion of connectors and PCB edge contacts may cause reliability problem in the system.
Moisture is a corrosion agent.
To control Corrosion, humidity should be controlled.
Cleaning fluids should be dried so as to control moisture.

32. Rough Handling Improper handling of the system causes damage.
The system should be kept at a clean and smooth surface.
The system should not be moved from its place frequently.
Careful handling of the system and its peripheral is a simple remedy.

33. Installing The Board Steps to install a circuit board:
Set jumpers & switches on the board.
Install the board in correct slot.
Reboot the system and let the OS detect the card and install drivers.
Test the operation of the board.
Test the compatibility of the board with other devices of the system.

34. Configuring circuit board
When a circuit board is installed, it may or may not function properly.
The non working is because of the conflicts of the new board with the existing ones.
Configuring the board is essential.
Configuring provides s/w support,consists of assigning resources to the device.

35. …Configuring circuit board
The installation of new board may require the following:
Specify COM port for MODEM.
Specify LPT port for printers.
Select DMA channels on board.
Select IRQ lines on the board.
Select RAM & ROM addresses on the board & load proper drivers.

36. Power supply
The system used to deliver constant DC voltage to electronic circuits is called power supply.
Normally all PCs are given supply by switch mode power supply(SMPS).
SMPS are digital in nature, the other Linear mode power supply(LMPS) are based on transformers.

37. Installing Power Supply
Steps to install power supply:
Insert the power supply and secure it to the board.
Connect it to the motherboard and other devices requiring power.
Plug in the power cord and check whether all devices are supplied the exact voltage.

38. Power supply problems
Sometimes the power supply capacity is inadequate for system expansions.
Common power problems are as following:
Lost data on hard disk.
Damaged chips on circuit boards.
Random memory errors.
Frequent automatic booting of the system.
Freezing up of the computer.

39. Overview the 'brains' types of memory the processor
1. Inside a PC (AT & ATX)
2. The Motherboard
3. RAM
4. ROM
5. CMOS Memory
6. The CPU
7. Expansion Slots
8. Booting the Computer
the 'brains'
types of memory
the processor

40. AT and ATX
The motherboard is an integral part in a computer since it is where all the components are attached to. ‘¨There are many standards for motherboards and the cases that holds them. The most prominent standards are AT and ATX. AT is a very old standard that was created by IBM for their own computers. ATX was developed by Intel to address some of the shortcoming of the AT standard that makes it unsuitable for the varied demands of personal computing.
AT boards were much bigger compared to ATX boards. ATX boards were made narrower by almost 4 inches to ensure that there is no overlap.

41. AT and ATX Cont..
The ATX specification was set forth publicly by Intel Corp. in The ATX specification was released as a successor to the AT specification. The necessity for this action on Intel's part was that the AT form factor was significantly antiquated, and possessed several design flaws when coupled with the modern computer hardware of the time. Though Intel has subsequently released the BTX form factor, it has not taken hold as an industry-standard and as a corollary, the ATX specification continues to be updated and revised.

42. AT and ATX Cont..
ATX form factor is the governing specification concerning the motherboard's dimensions, electrical connectivity and I/O interface placement. The specifications govern acceptable power supplies, cases and the overall maximum size of hardware devices that can be installed on the motherboard. For example, the current ATX specification, revision 2.2, requires a 24 pin power connector, and is 12-by- 9.6 inches in dimension. The design also allows for further spacing between PCI-e interfaces on the motherboard to accommodate larger graphics cards which have come into use as of 2007.

43. AT and ATX Cont..
Another shortcoming of the AT system is in the ports at the back. AT boards only had the most minimal amount connectors in order to maintain compatibility with AT cases. If you like more connectors, you would need to add flying leads to unused expansion slots. ATX cases allowed manufacturers to produce their own custom backplates to suit their motherboards. This allowed most ports to be integrated to the board and moved up, making it much less of an effort to install a new motherboard and even frees up some of the expansion slots taken up by the ports.

44. AT and ATX Cont..
ATX boards also introduced the ‘soft off’ capability. Prior to ATX, the power switch was directly connected to the power supply and the computer cannot turn itself off. ATX cases moved the switch to the motherboard. Computers then had the ability to turn itself on or off depending on its programming. You would no longer need to wait for the computer to safely shutdown before turning it off. It also paved the way for the additional features like WOL (Wake On Lan) that allows computers to be turned on remotely via its network adapter.

45. AT /ATX Summary:
1. AT is an old standard that has been totally replaced by ATX 2. AT boards are wider compared to ATX by almost 4 inches 3. ATX allows board makers to customize the ports in the back with backplates which is not possible with AT 4. AT computers had their power switches connected directly to the power supply while in ATX systems, the switch is connected to the motherboard

46. Differences Between AT & ATX Power Supplies
AT (Advanced Technology) and ATX (Advanced Technology Extended) are two incompatible power supply standards. While both power supplies share some of the same connectors, the technology behind both of them is quite different, requiring different motherboards and computer cases. The AT style was used from approximately , while the ATX standard is current.

47. Main Power Connector
The main power connector on AT and ATX power supplies are very different, and require different motherboards because of this. The main power connector on an AT power supply is actually two separate six-pin connectors that plug into the motherboard side by side in a single row. The ATX main power connector is a single 20 or 24-pin connector that places the pins on two rows.

48. Power Switch
The power switch of AT style power supplies is integrated directly into the power supply itself. This is a physical switch that turns the power supply on and off. ATX style power supplies use a "soft switch" that is controlled by the motherboard. This enables a computer with an ATX power supply to power off via software.

49. Wattage
Older power supplies provide a lower wattage rating than newer ones. Newer ATX style power supplies typically provide 300 or more watts, whereas AT style power supplies typically provide wattage of less than 250.

50. Connectors
Though AT and ATX power supplies share many connectors, ATX power supplies may have connectors, such as SATA and 4-pin ATX12V, that never appeared on AT power supplies due to the technology post-dating the AT power supply. Additionally, an AT power supply has more mini-Molex connectors for devices such as floppy drives.

51. Extended ATX
The extended ATX, or eATX, form factor was originally released as a workstation level motherboard specification. The physical dimensions of the motherboard could be 12-by-13 inches. This somewhat dramatic increase in size is due to the fact that enterprise level motherboards are required to house much more internal hardware than consumer level computers. Recently, however, there has been a higher consumer user demand for this form factor as technologies such as NVIDIA's SLI and ATI's Crossfire call for very large motherboards to accommodate two to four graphics cards, each two PCI slots in width.

52. Inside a PC CD-ROM drive Power supply Hard disk drive Mother board
Floppy
disk drive
Sound/network
cards
Wires and
ribbon cables

53. The Motherboard
The most important part of a PC is the motherboard. It holds:
the processor chip
memory chips
chips that handle input/output (I/O)
the expansion slots for connecting peripherals
Some chips are soldered onto the motherboard(permanent), and some are removable (so they can be upgraded).

54. A Chip
A chip (microchip) is an integrated circuit - a thin slice of silicon crystal packed with microscopic circuit elements
e.g. wires, transistors, capacitors, resistors

55. Motherboard Picture Read-only Memory Random Access Memory (RAM) (ROM)
chips.
Read-only Memory
(ROM)
chips
Expansion slots
Processor chip
(the CPU)

56. Moving Data RAM via expansion cards
A data bus (a data path): connects the parts of the motherboard.
RAM
via expansion cards

57. RAM Random Access Memory (RAM).
RAM is used to hold programs while they are being executed, and data while it is being processed.
RAM is volatile, meaning that information written to RAM will disappear when the computer is turned off.
continued

58. RAM contents can be accessed in any (i.e. random) order.
By contrast, a sequential memory device, such as magnetic tape, forces the computer to access data in a fixed order because of the mechanical movement of the tape.

59. RAM Storage Each RAM location has an address and holds one byte of
data (eight bits).

60. How much RAM is Enough?
Computers typically have between 64, 512 Mb (megabytes), 1GB….7GB (gigabyte) and more.
RAM access speeds can be as fast as 8 nanoseconds (8 billionth of a second).
The right amount of RAM depends on the processor speed and software you are using.
You can install extra RAM.

61. Virtual Memory
Virtual memory uses part of the hard disk to simulate more memory (RAM) than actually exists.
It allows a computer to run more programs at the same time.
Virtual memory is slower than RAM.

62. ROM Read-Only Memory can be read but not changed.
It is non-volatile storage: it remembers its contents even when the power is turned off.
ROM chips are used to store the instructions a computer needs during start-up, called firmware.
Some kinds of ROM are PROM, EPROM, EEPROM, and CD-ROM.

63. CMOS Memory
A computer needs a semi-permanent way of keeping some start-up data
e.g. the current time, the no. of hard disks
the data may need to be updated/changed
CMOS memory requires (very little) power to retain its contents.
supplied by a battery on the motherboard
the battery

64. The CPU
The Central Processing Unit (CPU) is the chip on the motherboard that acts as the "computer's brain"
it does calculations, and coordinates the other motherboard components
CPU examples: the Pentium, the PowerPC chip
The CPU is also known as the processor or microprocessor.

65. Some Processors (CPUs)
Pentium Chip
PowerPC Chip
Chip Fan

66. The CPU and RAM The RAM The CPU contains data processes data.
and programs.
The CPU
processes data.
The data bus transports the
processed data to the RAM so
it can be stored, displayed, or
output.

67. The CPU in Action
The CPU

68. The instruction pointer in the CPU's control unit stores the location of the next program instruction to be executed.
The instruction is loaded into the instruction register to be carried out.
registers are local memory on the CPU

69. The ALU (arithmetic logic unit) executes the instruction.
The result is placed in the accumulator (another register), then stored back in RAM or used in other CPU operations.

70. The CPU Instruction Cycle
The CPU executes a series of instructions by looping through an instruction cycle.
The speed of the
instruction cycle
is controlled by
the CPU's clock.

71. The System Clock
The system clock sends out 'ticks' to control the timing of all the motherboard tasks
e.g. it controls the speed of the data bus and the instruction cycle
The time it takes to complete an instruction cycle is measured in megahertz (MHz).
1 MHz = one million cycles per second

72. Two Measures of CPU Size
Word size: the number of bytes the CPU can process at once.
depends on the number of registers in the CPU;
depends on the size of the data bus
Cache size: the cache is high-speed memory on the CPU that stores data which is needed often.

73. Expansion Slots continued Expansion slot containing an expansion card.
Most expansion cards
contain a port.
Data originates
in RAM
The expansion bus
transports data through
the motherboard.
A connector cable plugs
into the port, and leads
to a peripheral.
continued

74. Common expansion cards:
graphics card (for connecting to a monitor)
network card (for transmitting data over a network)
sound card (for connecting to a microphone and speakers)
Most PCs offer 4-8 expansion slots.

75. Expansion Slot Types
There are several different types of expansion slot:
ISA: older technology, for modems and slow devices
PCI: for graphics, sound, video, modem or network cards
AGP: for graphics cards

76. Connector Cables
continued

78. Booting a Computer This is not an example of computer booting.
Booting is the sequence of computer operations from power-up until the system is ready for use
this includes hardware testing, and loading the OS
This is not an
example of
computer booting.

79. Other Booting Tasks The computer checks the CMOS memory.
The computer loads configuration settings from Config.sys or the Windows Registry.

80. Common Problems #1
If nothing happens, the system is not getting power.
When you turn on a computer,
you should see the power light
and hear the fan.
Fan
Power light

81. Common Problems #2
If the ROM chips, RAM, or processor are broken, then the computer will stop or 'hang'
the light and fan will be on, but...
there will be no messages on the screen

82. Common Problems #3
The Power-On Self-Test (POST) automatically checks for problems in the computer.
POST checks:
the graphics card, RAM, the keyboard
performs drives test
hard drive, CD drives, floppy drive
Problems are reported by various beeps, or by on-screen messages.

83. Common Problems #4 Configuration data is missing or corrupted
in the CMOS or the Windows Registry
This will generate on-screen messages.

84. Windows Safe Mode
If MS Windows cannot complete booting, it may start in Safe Mode.
Safe Mode is a limited version of Windows that allows you to use only the mouse, monitor, and keyboards
no peripherals
the screen icons will probably look very large

85. Windows Safe Mode Picture

86. REFERENCES
B.A. (Mahayana Studies) Introduction to Computer Science November March 2006