Computer Hardware & Troubleshooting

Practical File

Submitted to: Submitted By:

Ms. Soni Saurabh Kumar Gupta1120739

CO4

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INDEX

S.No. Experiment Page no.

1 To solder and de-solder various components. 3-7

2 To check and measure various supply voltages 8-9

3 To make comparative study of motherboards. 10-13

4 To observe and study various cables, connectors and parts used in computer communication

14-18

5 To study various cards used in a system – display card, LAN card. 19-22

6 To remove, study and replace floppy disk drive 23-26

7 To remove, study and replace hard disk 27-31

8 To remove, study and replace CDROM drive 32-37

9 To study monitor, its circuitry and elementary fault detection 38-39

10 To study printer assembly 40-41

11 To observe various cables and connectors used in networking 42-44

12 To study parts of keyboard and mouse. 45-48

13 .To assemble a PC 49-51

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EXPERIMENT -1

AIM: To solder and de-solder various components.

THEORY:

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Electronic soldering connects electrical wiring and electronic components to printed circuit board (PCBs). Soldering provides reasonably permanent but reversible connections.The eutectic alloy of 63% tin and 37% lead is used as a soldering filler material for electronic soldering

Preparing To Solder:

Tinning the Soldering Tip:

Before use, a new soldering tip, or one that is very dirty, must be tinned. "Tinning" is the process of coating a soldering tip with a thin coat of solder. This aids in heat transfer between the tip and the component you are soldering, and also gives the solder a base from which to flow from.

Step 1: Warm Up Iron

Warm up the soldering iron or gun thoroughly. Make sure that it has fully come to temperature because you are about to melt a lot of solder on it. This is especially important if the iron is new because it may have been packed with some kind of coating to prevent corrosion.

Step2: Thoroughly Coat Tip In Solder

Thoroughly coat the soldering tip in solder. It is very important to cover the entire tip. You will use a considerable amount of solder during this process and it will drip, so be ready. If you leave any part of the tip uncovered it will tend to collect flux residue and will not conduct heat very well, so run the solder up and down the tip and completely around it to totally cover it in molten solder.

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Step 3: Clean The Soldering Tip

After you are certain that the tip is totally coated in solder, wipe the tip off on the wet sponge to remove all the flux residue. Do this immediately so there is no time for the flux to dry out and solidify.

Soldering A Printed Circuit Board (PCB)

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Step 1: Surface Preparation

A clean surface is very important if you want a strong, low resistance solder joint. Once you have cleaned the board down to shiny copper you can use a solvent such as acetone to clean any bits of the cleaning pad that may remain and to remove chemical contamination from the surface of the board. A few blasts with compressed air will dry out the board and remove any junk that may have built up in the holes.

Step 2: Component Placement

In the image below, a resistor is ready to solder and is held in place by slightly bent leads.

Step 3: Apply Heat

To heat the joint you will lay the tip of the iron so that it rests against both the component lead and the board.

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Step 4: Apply Solder To The Joint

Once the component lead and solder pad has heated up, you are ready to apply solder. Touch the tip of the strand of solder to the component lead and solder pad, but not the tip of the iron. If everything is hot enough, the solder should flow freely around the lead and pad. You will see the flux melt liquify as well, bubble around the joint (this is part of its cleaning action), flow out and release smoke

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Steps to desolder:

Step 1: Heat:Place the exposed desoldering braid over the solder joint on the circuit board that you want to desolder. Press down on top of the desoldering braid with your soldering iron until you see and/or feel the solder beneath the braid start to liquefy and flow.

Step 2: Remove:

As soon as the solder starts to liquefy, count to two and then remove the soldering iron and lift away the braid by gripping its container If all went well, the blob of solder on the circuit board is now gone and you can see the freed pin that you have successfully desoldered. If all of the solder has not been removed and the pin is still attached to the circuit board, simply repeat the process until the pin is free from the solder

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EXPERIMENT -2

AIM: To check and measure various supply voltages of PC

THEORY: The PC power supply is primarily designed simply to take AC from the wall outlet & convert into the much lower DC voltages needed by the system. When system shut down, it must prevent any voltage overshoot & fluctuations so that none of sensitive circuits are exposed to any damaging voltage fluctuation .It must include some way of providing cooling air flow, because of the conversion process always has some heat by product.

Converting AC to DC power

The switching mode power supply used in a PC is much lighter & more efficient then the more common linear mode power supplies. Often used in the past systems, & therefore is a good choice for a power supply. The first part of PC switching power supply is rectifier. Next is the switches circuit which chops up .the input voltage at a frequency much higher than the AC supply. Furthermore, any load fluctuation are fed back to the input in such away as to cause switcher circuit to adjust the input power to the transformer so that it can maintain the output voltage to final regulator. The switcher circuitry itself generate EMI, which can feed back into the building AC power & contribute to problems elsewhere.

Output voltage supply voltage lines

The voltages delivered by the power supply to the motherboard must remain stable in spite of a wide range of input AC voltage and varying load conditions

+5 volt supply

This is the basic supply voltage for nearly all-electronic components. The 5V supply is now sometimes used by motors, but usually only in smaller drives, such as “2.5inch” & some 3.5inch drive. The +5V supply wires should always be red in any standard PC system. If regulated voltage is adjustable, the jumpers or switches will probably be found near regulator circuit.

+12V power supply

This line supplies most if not all, motors in the system, from drive motor to cooling fans. Because motors often used up to 50% more power on start up then while running ,the +12V supply may show adequate operation while running , but be in an over loaded condition during the 5 seconds or so immediately .after the system or a particular drive is turned on .

-12 V power supply

This supply line is usually used for some of the same communications circuits that use +12 V line.

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-5 V power supply

This voltage is no longer used by any device and is retained only the purpose of backward compatibility with the older ISA slots. Originally, this voltage was used by some DRAM memory chips in original PC design. Micro channel system omitted this voltage from the power supply entirely.

+3.3V power supply

Starting with the ATX designed in 1995 any system with ATX compatible power supplies include a 3.3 volt supply line from the power supply to the motherboard. Currently most CPUs & DRAM used 3.3V as well as some PCI adapter cards.

Power Supply Control Signals

Although the primary function of the power supply is indeed to supply clean electrical power to systems, the power supply also interacts with the motherboard to perform an increasing number of functions, including CPU startup, system power down, voltage and temperature detection and other functions.

Power Good Signal

The signal is actually a logic level signal designed as a power supply output signal to the CPU circuitry, to start the CPU running.

Power On

Prior to the ATX standard, AT compatible power supplies either had the power switch mounted on the back or side of power supply itself ,or had a remote switch mounted on the front panel.The power on signal wire is apart of ATX standard and carries only a low voltage logic level signal from the motherboard to the power supply, telling it when to turn on and when to turn off.

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EXPERIMENT -3

AIM: To make comparative study of motherboards.

THEORY:

What is a motherboard?A motherboard is the central or primary printed circuit board making up a complex electronic system, such as a modern computers. It is also known as a main board, base board, system board, and planar board A motherboard, is like a backplane, provides the electrical connections by which other components of the system communicate.

History of motherboards By the late 1990s, motherboards began to have full range of audio, video, storage and networking functions on them. Higher end systems for 3D gaming and graphic cards were also included later .Micronics , Mylex , AMI, DTK, Orchid Technology, Elitegroup , etc. were few companies that were early pioneers in the field of motherboard manufacturing but, companies like Apple and IBM soon took over. They offered high end, sophisticated motherboards that included upgraded features and superior performance over prevailing motherboards.

TYPES OF MOTHERBOARD:

There are four types of MOTHERBOARD.

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XT Motherboards:

XT Stands for eXtended Technology. These are all old model motherboard. In this motherboards, we find old model processor socket LIF (Low Insertion Force) sockets, ram slots Dimms and ISA (Industry Standards Architecture) slots, 12pin Power Connector and no ports.

They have slot type processors, Dimms memory modules, ISA slots for add-on card, and no ports. There are connectors and add-on cards for ports.

Eg: Pentium-I, Pentium-MMX, Pentium -II and Pentium-II Processors.

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AT Motherboards:

AT stands for Advanced Technology. Advanced Technology Motherboards have PGA (Pin Grid Array) Socket, SD Ram slots, 20pin power connector PCI slots and ISA slots. we find the above components on AT motherboards.

Eg: Pentium-III Processors

Baby AT Motherboards:

Baby AT Motherboards have the combination of XT and AT. They have both slot type processor sockets and PGA processor sockets, SD Ram slots and DDR Ram slots, PCI slots and ISA slots, 12 Pin power connector and 20Pin power connector and Ports.

Eg: Pentium-III and Pentium-IV

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ATX Motherboards:

ATX stands for Advanced Technology eXtended. latest motherboards all are called as ATX motherboards. designed by ATX form factor. In this motherboards, we find MPGA Processor Sockets, DDR Ram slots, PCI slots, AGP slots, Primary and secondary IDE interfaces, SATA connectors, 20pin and 24 pin ATX power connector and Ports.

Eg: Pentium-IV, Dual Core, Core 2 Duo, Quad Core, i3, i5 and i7 Processors.

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EXPERIMENT -4

AIM: To observe and study various cables, connections and parts used in computer communication.

THEORY:

Motherboard:Motherboard is glue which binds all the components of a Computer. Every component directly or indirectly attached/installed/connected to a system has a connection to motherboard, because it is the base on which system & its components/peripheral devices stand and perform. Technically speaking motherboard is a PCB- Printed Circuit Board that provides an interconnection to almost every component present in a PC. It is also known as system/main board.

Following are the main components of a motherboard:

•CPU Socket & Memory Slots

•ISA, PCI & AGP Expansion Slots

•CMOS Battery

•Power Connectors

•Memory Slots

•Chipset

•Serial/ Parallel/ USB ports etc.

Peripheral Component Interconnect (PCI Slots)

• Introduced by Intel in 1992. Widely in use today.

•Requires an additional bridge chip to connect to the I/O of the CPU.

•Operates on 33MHz, & capable of transferring data at 132 MB/sec.

•Important feature of PCI is the model for the PNP (Plug-n-Play) specification, which

means that PCI cards could be configured via software, rather than through jumpers as was the case with ISA cards.

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•Accelerated Graphics Port (AGP)

•The AGP port is a dedicated graphics port based on PCI.

•It’s a dedicated point-to-point channel that enables the graphics controller to access

main memory, bypassing the bottleneck of the PCI bus.

•It allows textures to be stored in main memory rather than video memory.

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•The AGP channel is 32 bits wide and

•Runs at 66 MHz, giving a bandwidth of 266 MB/sec.

•AGP also supports two optional faster modes, giving throughputs of 533 MB/sec

and 1.07 GB/sec.

•Random Access Memory (RAM)

Old 72-pin SIMM-type memory sockets

•A SIMM is a small circuit board designed to hold a set of RAM chips.

•Two types of SIMM's have been in general use. 30-pin SIMM's and 72-pin SIMM's.

•30-pin SIMM's have 8-bit data buses; 72-pin SIMM's have 32-bit data buses.

•Enhanced Integrated Drive Electronics (EIDE slot)

•Enhanced (sometimes "Expanded") IDE is a standard electronic interface between

your computer and its mass storage drives.

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•Makes it possible to address a hard disk larger than 528 Mbytes.

EIDE also provides faster access to the hard drive, support for Direct Memory Access (DMA), and additional drives, including CD-ROM .

•Analog Audio Input Connectors

•These are typically used for CD ROM drives. Since the CD ROM drive can deliver

audio via the 40-pin IDE connection, the analog audio connectors are not generally needed. If you have a video capture card, you may need to use the analog audio input to get the sound into the computer.

•Front panel switches and LEDs

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•There are typically 4 connections (hard drive LED, power/message LED, power

switch and reset switch).

•The LED connections are polarity sensitive (if connected in reverse, the LEDs will

not work).

•The colored wire is generally positive and the white/black wire is negative.

•I/O Ports

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EXPERIMENT-5

AIM: To study various cards used in a system eg. Display Card and LAN card.

THEORY:

1). NETWORK CARD:

Network card is used to convert physical and logical connection to LAN(network).The Adaptor is connected with a network cable that connects your computer with other systems .The LAN card is fixed on the motherboard expansion slots .Some LAN Cards also contain AUI port on them.

2).SOUND CARD:

Sound Card is used to provide sound to your system .The main purpose of sound card is to provide sound through multimedia speakers , headphones , mic attached to the system .The sound card can be used to record voice as well as play music from CD's or it can play sound files from Hard Disk.

3).EXPANSION CARD (DAUGHTER CARD) :

This card has PCI and ISA slots on that. Incase if your system requires additional slots or if your motherboard slots are not functioning properly then you are required to insert in your system the Add-on card .The Add-on card is installed in your motherboard's Bus slot that allows to access the slots on the Add-on card.

4).DISPLAY CARD:

The Display Card is used to connect the monitor to the System .Without the Display card one will not get the output on the monitor screen .There are four types of Display cards used in the system.1) VGA(Video Graphic Array) Card2)SVGA(Super Video Graphic Array) Card3)2D Graphic Accelerator Card 4)3D Graphic Accelerator Card

NETWORK CARD

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It is also known as a Network Adapter. It is an Integrated circuit board that plugs into the internal circuitry of the computer which allows the members of a local-area network to communicate with each other. NIC is the physical interface from the computer or peripheral to the medium. The Medium may be physical cable, such as twisted pair wiring, coaxial cable, fiber optic or even wireless.

FunctionsMost computers use parallel data lines internally to send data between the CPU and the adapter cards. This is called a Bus. Most networking media transmit data in a single line, called serial transmission. The NIC translates parallel into serial for outgoing messages and serial into parallel for incoming messages. Prior to the invention of NICs, data was sent via serial ports on the computer.Some NICs offer integrated field-programmable gate arrays (FPGAs) for user-programmable processing of network traffic before it reaches the host computer, allowing for significantly reduced latencies in time-sensitive workloads. Moreover, some NICs offer complete low-latency TCP/IP stacks running on integrated FPGAs in combination with user space libraries that intercept networking operations usually performed by the operating system kernel

Implementation

Whereas network controllers used to operate on expansion cards that plugged into a computer bus, the low cost and ubiquity of the Ethernet standard means that most new computers have a network interface built into the motherboard. Newer server motherboards may even have dual network interfaces built-in. The Ethernet capabilities are either integrated into the motherboard chipset or implemented via a low-cost dedicated Ethernet chip, connected through the PCI (or the newer PCI Express) bus. A separate network card is not required unless additional interfaces are needed or some other type of network is used.

The NIC may use one or more of two techniques to indicate the availability of packets to transfer:

• Polling is where the CPU examines the status of the peripheral under program control .

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• Interrupt -driven I/O is where the peripheral alerts the CPU that it is ready to transfer data , and may use one or more of two techniques to transfer packet data

• Programmed input/output is where the CPU moves the data to or from the designated peripheral to memory.

• Direct memory access is where an intelligent peripheral assumes control of the system bus to access memory directly. This removes load from the CPU but requires more logic on the card. In addition, a packet buffer on the NIC may not be required and latency can be reduced.

GRAPHIC CARD

A video card (also called a video adapter, display card, graphics card, graphics board, display adapter, graphics adapter or frame buffer and sometimes preceded by the word discrete or dedicated to emphasize the distinction between this implementation and integrated graphics) is an expansion card which generates a feed of output images to a display (such as a computer monitor). Within the industry, video cards are sometimes called graphics add-in-boards, abbreviated as AIBs, with the word "graphics" usually omitted .

HistoryStandards such as MDA, CGA, HGC, Tandy, PGC, EGA , VGA , MCGA , 8514 or XGA were introduced from 1982 to 1990 and supported by a variety of hardware manufacturers.Virtually all current video cards are built with either AMD -sourced or Nvidia -sourced graphics chips. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics , MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors (multi-monitor).

Components of a Graphic Card

1).GPU(Graphics Processing Unit) : A GPU is dedicated Graphic processor optimized for floating point calculations which are fundamental to 3D graphics rendering .

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2).Video Memory : The memory capacity of most modern video cards ranges from 128 MB to 8 GB. Since video memory needs to be accessed by the GPU and the display circuitry, it often uses special high-speed or multi-port memory, such as VRAM , WRAM, SGRAM, etc. Video memory may be used for storing other data as well as the screen image, such as the Z-buffer, which manages the depth coordinates in 3D graphics, textures , vertex buffers , and compiled shader programs.

3).RAMDAC : The RAMDAC , or Random Access Memory Digital-to-Analog Converter, converts digital signals to analog signals for use by a computer display that uses analog inputs such as Cathode ray tube (CRT) displays. The RAMDAC is a kind of RAM chip that regulates the functioning of the graphics card.

4).Motherboard Interface :It is the connection system which connects graphics card with motherboard system .Although there are many connection systems since 1974 .Nowadays AGP and PCI-Express slots are widely used connection system .

5).Cooling Devices : Graphics card uses lots of electricity which is converted into heat .If heat isn’t dissipated then card could get overheated and get damaged. Cooling devices are incorporated to transfer heat elsewhere.

6)Outputs : These are the connection systems which connects graphics card with display .a) VGA : Analog based standard adopted in 1980s designed for CRT displays . Also called as VGA connector .b) DVI : Digital based standard designed for flat panel screens such as plasma , LCD ,display ,video projectors etc. This DVI port is used for HDTV .c) S-Video : These digital based VIVO are used in televisions, video recorders, gaming consoles etc.

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EXPERIMENT -6

AIM: To remove, study and replace floppy disc drive.

THEORY:

A floppy disk, also called a diskette, is a disk storage medium composed of a disk of thin and flexible magnetic storage material, sealed in a rectangular plastic carrier lined with fabric. Floppy disks, initially as 8-inch (200 mm) media and later in 5¼-inch (133 mm) and 3½-inch (90 mm) sizes, were a medium of data storage and exchange from the mid-1970s well into the 2000s.

HISTORY:

The earliest floppy disks, developed in the late 1960s, were 8 inches (200 mm) in diameter and became commercially available in 1971. In 1973 IBM announced its first media as "Type 1 Diskette" but the industry continued to use the terms "floppy disk" or "floppy". In 1976, Shugart Associates introduced the first 5¼-inch FDD and by 1978 there were more than 10 manufacturers producing such FDDs. Through the early 1980s, limitations of the 5¼-inch format became clear. It was itself too large and as the quality of recording media grew, data could be stored in a smaller area. Solutions were developed, with drives at 2, 2½, 3 and 3½ inches (and Sony's 90.0 mm × 94.0 mm disk) offered by various companies and shared a number of advantages over the old format. This included a rigid case with a sliding metal cover over the head slot and a sliding write. A variant on the Sony design, introduced in 1982 by a large number of manufacturers was rapidly adopted. By 1988 the 3½-inch was outselling the 5¼-inch.By the mid-1990s, the 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk.

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The 3½-inch vs The 5¼-inch

• The 3½-inch had smaller size and had a plastic case, which provided better protection from dirt and other environmental risks.

• While the 5¼-inch disk was available cheaper per piece throughout its history, usually with a price in the range of 1/3 to 2/3 of a 3½-inch disk.

Structure and WorkingThe 5¼-inch disk has a large circular hole in the center for the drive's spindle. It has a small oval aperture in both sides of the plastic to allow the drive's heads to read and write data.A small notch on the right of the disk identifies that it is writable, detected by a mechanical switch or phototransistor above it. If it is not present, the disk is read-only.

Another LED/photo-transistor pair located near the center of the disk detects the index hole once per rotation in the magnetic disk. It is used to detect the angular start of each track and whether the disk is rotating at the correct speed or not. Early 8-inch and 5¼-inch disks had physical holes for each sector and were termed hard sectored disks. Later soft sectored disks had only one index hole, and sector position was determined by the disk

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controller or low level software from patterns marking the start of a sector. The core of the 3½-inch disk is the same as the other two disks, but the front has only a label and a small aperture for reading and writing data, protected by the slider.Rather than having a hole in the center, it has a metal hub which mates to the spindle of the drive. Typical 3½-inch disk magnetic coating materials are:DD: 2 µm magnetic iron oxideHD: 1.2 µm cobalt-doped iron oxideED: 3 µm barium ferriteTwo holes at the bottom left and right indicate whether the disk is write-protected and whether it is high-density

8-inch Floppy DiskThe first floppy disk 8 inches in diameter, was protected by a flexible plastic jacket and was a read-only device used by IBM as a way of loading microcode. IBM's 1973 introduction of the 3740 data entry system began the establishment of floppy disks, called by IBM the "Diskette 1," as an industry standard for information interchange. Later versions of 8-inch floppy disk could store up to 1.2 MB.

5¼-inch Floppy Disk (a.k.a. Mini diskette, Mini disk, or Minifloppy)Introduced in 1976 by Shugart Associates.Single sided floppy came in 2 variants 8 sectors/track: 160 KB memory(introduced in 1981) 9 sectors/track: 180 KB memory(introduced in 1983)Capacity of Double-sided floppy: 360 KB (introduced in 1983)Capacity of High-Density (HD) floppy: 1.2 MB (introduced in 1984)

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3½-inch Floppy DiskIntroduced in 1982Various capacity variants of floppy diskSingle-sided GCR (Apple Mac): 400 KB (1984)Single-sided MFM (IBM PC): 360 KB (1985)Double-sided GCR (Apple Mac): 800 KB (1986)Double-sided MFM (IBM PC): 720 KB (1986)HD: 1.44 MB (1987)ED: 2.88 MB (1991)

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EXPERIMENT -7

AIM: To remove, study and replace Hard Disk .

THEORY: A hard disk drive (HDD), hard disk, hard drive or fixed disk is a data storage device used for storing and retrieving digital information using one or more rigid ("hard") rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads arranged on a moving actuator arm, which read and write data to the platter surfaces.[2] Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order rather than sequentially. An HDD retains its data even when powered off.

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HISTORY:HDDs were introduced in 1956 as data storage for an IBM real-time transaction processing computer and were developed for use with general-purpose mainframe and minicomputers. The first IBM drive, the 350 RAMAC, was approximately the size of two refrigerators and stored five million six-bit characters (3.75 megabytes) on a stack of 50 disks.In 1962 IBM introduced the model 1311 disk drive, which was about the size of a washing machine and stored two million characters on a removable disk pack. Users could buy additional packs and interchange them as needed, much like reels of magnetic tape. Later models of removable pack drives, from IBM and others, became the norm in most computer installations and reached capacities of 300 megabytes by the early 1980s. Non-removable HDDs were called "fixed disk" drives.

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COMPONENTS OF A HARD DISK

Platters : The platters are the circular discs inside the hard drive where the 1s and 0s that make up your files are stored. Platters are made out of aluminium, glass or ceramic and have a magnetic surface in order to permanently store data. On larger hard drives, several platters are used to increase the overall capacity of the drive. Data is stored on the platters in tracks, sectors and cylinders to keep it organized and easier to find.

The Spindle : The spindle keeps the platters in position and rotates them as required. The revolutions-per-minute rating determines how fast data can be written to and read from the hard drive. A typical internal desktop drive runs at 7,200 RPM, though faster and slower speeds are available. The spindle keeps the platters at a fixed distance apart from each other to enable the read/write arm to gain access.

The Read/Write Arm : The read/write arm controls the movement of the read/write heads, which do the actual reading and writing on the disk platters by converting the magnetic surface into an electric current. The arm makes sure the heads are in the right position based on the data that needs to be accessed or written; it's also known as the head arm or actuator arm. There is typically one read/write head for every platter side, which floats 3 to 20 millionths of an inch above the platter surface.

Actuator : The actuator or head actuator is a small motor that takes instructions from the drive's circuit board to control the movement of the read/write arm and supervise the transfer of data to and from the platters. It's responsible for ensuring the read/write heads are in exactly the right place at all times.

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MAGNETIC STORAGE

An HDD records data by magnetizing a thin film of ferromagnetic material on a disk. Sequential changes in the direction of magnetization represent binary data bits. The data is read from the disk by detecting the transitions in magnetization. User data is encoded using an encoding scheme, such as run-length limited encoding, which determines how the data is represented by the magnetic transitions.

HOW TO REMOVE A HARD DRIVE

Computer hard drives store everything from photos to music to files. In short, they store everything that is on your computer. If something goes wrong with your hard drive, there is no need to go buy a new computer. Removing the hard drive of a PC yourself and replacing it with a newly purchased one can save you a lot of money. Use these steps to learn the correct way on how to remove a hard drive.

STEPS:

1. Back up your data. We're going to do our best not to lose any data, but as Murphy's Law will tell you, things happen. It's better to be ready with a little precautions than to risk losing all your data. Copy your information onto an external hard drive or use another form of backup like online backup prior to removing your current hard drive. If your hard drive has failed and your data has been lost, skip this step.

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2. Turn off your computer and unplug it from everything. You're going to need to get inside the computer, and it'll be a lot easier if it doesn't hang up on wires or suddenly turn on and electrocute you. Unplug the power source, monitor and any other devices.3. Open the computer case. Each computer model is manufactured differently. Opening your specific case may involve removing a side panel with a screwdriver or pushing a button to open the case in a clamshell fashion. The owner's manual that came with your computer should detail the manner in which the case is opened. If your owner's manual is missing or you did not receive one, don't despair. Look carefully at your computer case and you'll probably be able to figure out how to remove it. Most older computers are secured with Phillips-head screws on the back.4. Locate the hard drive inside the computer case. Within the computer, the hard drive could be placed in a cage that's either fixed to the tower or removable, or it could be placed on a set of rails. The hard drive is a rectangular metal box the size and width of a small book. By convention, most computers locate the hard drive near the front of the case, near other drives (like your optical drive). If you look closely, your hard drive will be clearly labeled as such - don't go pulling random stuff out of your computer if you're not sure what it is!5. Determine how the hard drive is connected to the computer. Now that you've located the hard drive, you need to figure out how to remove it. You will need a screwdriver to open the cage and handle the drive if the hard drive is in a fixed or removable cage.6 Take the hard drive from where it rested in the tower. Hard drives will often sit on a set of rails towards the front of the computer case. Using both hands, carefully slide it outward. Pull carefully - if you encounter any resistance, stop! Nothing in a computer case should require any substantial amount of force - if you're pulling or pushing hard, you're probably doing it wrong. The hard drive will have two or more cables connected to it. If those are impeding on your ability to take out the hard drive, remove these cables first7. Remove the IDE ribbon cable. This is a broad, thin, usually gray ribbon running from your motherboard (or hard disk controller if present) to your hard drive. The cable may be connected to the hard drive with glue, but you should be able to work it out of place without much hassle. Carefully remove as much glue as you can and work the plug back and forth gently to break the glue.8. Remove the power connector. This will be a plastic, rectangular connector with one or two latches (depending on the level of power your computer's motherboard provides to the hard drive).This connector will usually be a lot more snug than the IDE ribbon cable. Make sure you're disengaging the latches on the plug and pull firmly on the connector. Take care not to bend any of the thin metal pins inside the plug9. Take the hard drive out of the case and put it into an anti-static bag. "Naked" hard drives removed from a computer are very sensitive to damage from moisture, dust and electrical shock. Anti-static bags are a cheap method of protecting your hard drive. Anti-static bags can be cheaply purchased at most office supply or computer stores. If you're throwing out or recycling your hard drive, you can skip this step.

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EXPERIMENT -8

AIM: To remove, study and replace CD ROM drive

THEORY:The acronym CD-ROM stands for compact disc-read only memory, denoting the fact that CD-ROM discs are read-only devices; data cannot be written to a CD-ROM by a conventional player.The four main types of Compact Disc formats are:1. CD Audio2. CD-ROM (Compact Disc-Read Only Memory)3. CD-I (Compact Disc-Interactive)4. CD-ROM/XA (CD-ROM Extended Architecture)

HISTORY:With all the improvements in technology over the years, one such development that has affected education was the release of CD-ROM players for computers. The need for the CD-ROM arose from the technological need for larger moveable storage space. In 1981 Sony, Philips and Polygram announced the impending introduction of a compact disc digital audio system to the world market within two years (Sony, 1997). True to their word the Compact Disc was launched in 1983; holding up to 550 MB of information, the first CDs were rarely filled to capacity, but with rapid increases in speed various applications came onto the market. The CD-ROM drive arose from the audio compact disc player and began to gain popularity during the late 1980’s. The numbers of CD-ROM drive sales is continually increasing.

STRUCTURE:The thickness of a CD can vary between 1.1 and 1.5mm. CDROM can store 720 MB of data. A CD consists of four layers. The biggest part is clear polycarbonate (nominally 1.2mm). There is a very thin layer of reflective metal (usually aluminum) on top of the polycarbonate. Then a thin layer of some protective material covering the reflective metal. A label or some screened lettering on top of protective material.

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CD vs. Magnetic Media

In Magnetic Media (like floppy/hard disk) the surface is arranged into concentric circles called “tracks”. Number of sectors per track is constant for all tracks. The CD has one single track, starts at the center of the disk and spirals out to the circumference of the disk. This track is divided into sectors of equal size.

CD Data Recording

Information is recorded on a CD using a series of bumps. In the recording, Lazer gun was used to write data to disk. Signal corresponding to 0 => laser off. Signal corresponding to 1 => laser on => burned disk surface into a point of losing the ability to reflect.

The unmarked areas between pits are called "lands”. Lands are flat surface areas. The information is stored permanently as pits and lands on the CD-ROM. It cannot be changed once the CD-ROM is mastered, this is why its called CD-ROM.

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Laser gun

Lens

Prism

Sensitive diode

Data ReadingLaser reflection on rotating disk surface, the pit - lost reflected rays => that is “0” signal, the land - reflected rays => that is “1” signal.

THREE MAIN COMPONENTS OF A CD ROM DRIVE1. Drive motor 2. Laser and lens system 3. Tracking mechanism

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How The CD Drive WorksA motor rotates the CD. The rotational speed varies so as to maintain a constant linear velocity (the disk is rotated faster when its inner "SPIRALS" are being read) .A laser beam is shone onto the surface of the disk. The light is scattered by the pits and reflected by the lands, these two variations encode the binary 0's and 1's. A light sensitive diode picks up the reflected laser light and converts the light to digital data.

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DVD vs. CDDVD uses a tighter spiral (track or helix) with only 0.74 microns between the tracks (1.6 microns on CDs). DVD recorders use a laser with a smaller wavelength, 635nm or 650 nm (visible red light) vs. 780nm (infrared) for CDs. DVD has smaller "burns" (pits) in the translucent dye layer (0.4 microns minimum vs. 0.83 microns minimum on CDs). These technologies allow DVDs to store large amounts of data.

ADVANTAGESStorage capacity is very high. A standard disc is able to store 650mb of data. This is the equivalent to approximately 2 million pages of text or 74 minutes of high quality music. The costs associated with CD-ROM storage are typically very low. CD-ROM drives are inexpensive and can be repaired or replaced easily.

DISADVANTAGESThey are relatively fragile. They are easily damaged, for example by accidental scratches or exposure to heat. CD-ROM drives are relatively slow in comparison to other storage devices, such as the hard disc drive. CD-ROM is a read only medium.

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EXPERIMENT -9

AIM: To study monitor, its circuitry and various presets and some elementary fault detection

THEORY:A monitor or a display is an electronic visual display for computers. The monitor comprises the display device, circuitry and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors used a cathode ray tube (CRT) about as deep as the screen size

CircuitryThe cathode ray tube (CRT) is a vacuum tube containing an electron gun (a source of electrons) and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen. The image may represent electrical waveforms (oscilloscope), pictures (television, computer monitor), radar targets and others.

The CRT uses an evacuated glass envelope, which is large, deep, heavy, and relatively fragile. Display technologies without these disadvantages, such as flat plasma screens, liquid crystal displays, DLP, OLED displays have replaced CRTs in many applications and are becoming increasingly common as costs decline.

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Faults and Detection :

Problems with CRT Monitors

1. CRT monitors can lose focus and/or brightness after some years of use and are

beyond the scope of this entry to rectify.

2. They may incorrectly display colours because colour "gun" or its associated control

electronics has died.

Problems with LCD/TFT Monitors

1. Failure of the backlight is the one fairly common issue in LCD technology due to

which the monitor goes dark and one usually can't see a thing.

2. Another common problem with LCD displays is the potential for stuck or broken

pixels, where the pixel either does not receive a voltage and remains black, or does

not respond to voltage changes and stays at a set luminance level.

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EXPERIMENT -10

AIM: To study printer assembly and elementary fault detection of DMP and laser printers.

THEORY:A printer is a peripheral which makes a persistent human readable representation of graphics or text on paper or similar physical media. Earlier Dot Matrix Printers (DMP) were popularly used. Nowadays laser printers are common.

Laser printing is an electrostatic digital printing process which uses the concept of static electricity.Basic Components of Laser printer are : 1. Drum2. Fuser3. Laser Scanning Assembly4. Toner

Printing is performed in following steps:• The photosensitive drum is electrostatically cleaned by erase lamps which illuminate

the drum’s photosensitive material to neutralize any electrical charges that remain on the drum. Moreover leftover toner from the previous image is removed by a rubber cleaning blade.

• Next uniform negative charge on the surface of the photosensitive drum is applied by the primary corona wire.

• After that a sweeping laser beam is used to discharge the potential in selected areas by focusing laser light on selected portions of the photosensitive drum which creates an electrostatic image.

• The invisible electrostatic image is developed into a visible image on the photosensitive drum when toner from a developer cylinder is transferred to discharged areas on the drum.

• The toner image on the photosensitive drum is transferred to the paper by first charging paper positive using a corona wire, so that negative toner particles stick to paper.

• . At the fusing station, toner is melted and forced into the paper by pressure and heat of the fusing roller to produce a permanent image.

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EXPERIMENT -11

AIM: To observe various cables and connectors used in networking.

THEORY:Cable is the medium through which information usually moves from one network device to another. There are several types of cable which are commonly used with LANs. The type of cable chosen for a network is related to the network's topology, protocol, and size. The most common cable types are discussed below:

Coaxial - Older ethernet technologies such as 10Base5 and 10Base2 used coaxial cable (RG-58). These network types are no longer in use. This type of network connection has made a recent comeback and is being used for broadband cable internet connections (RG-59).

Unshielded Twisted Pair (UTP) - UTP is a cable type that consists of two or more insulated copper conductors in which each pair of conductors are twisted around each other. Category 1 UTP cables are used for telephony connections. Category 3 and higher are used for Ethernet LAN connections. UTP is inexpensive and easy to work with.

Shielded twisted pair (STP) - This type of cable is the same as unshielded twisted pair (UTP), except that it has shielding around it to provide more protection against electromagnetic interference (EMI). Because of its higher cost, it is typically only used in environments where it is necessary.

Fiber Optic - Previously only used for WAN connections, fiber optic cabling is now increasingly being used on LANs as well for its capacity for longer distance and higher speeds. A fiber-optic system is similar to the copper wire system (UTP/STP), however, fiber-optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Fiber cables are made of transparent glass or plastic fibers which allow light to be guided from one end to the other. There are 2 types of fiber cabling - Single-mode fiber (SMF) and multi-mode fiber (MMF). MMF is the most common type used, however, SMF can support longer distances and higher speeds.

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Different type of connectors are :BNC - This connector has found uses with both broadcast television equipment and computer networks. With regards to networking, this connector was used on early 10Base-2 (Thinnet) Ethernet networks. It has a center pin connected to the center coaxial cable conductor and a metal tube connected to the outer cable shield. A rotating ring outside the tube locks the cable to the female connector.

F Connector - This connector is the one used for home broadband cable connections with coaxial cable. This male connector screws onto the female counterpart. The connection typically runs coax from the wall outlet to the cable modem. The cable modem will have a RJ-45 jack for connection a computer or wireless access point.

RJ-11 - Short for Registered Jack-11, a four or six-wire connector used primarily to connect telephone equipment in the United States (POTS). The cable itself is called category 1 (Cat 1) and is used for dial-up connections. Modems have rj-11 jacks that connect them to the wall outlet.

RJ-45 - Short for Registered Jack-45, it is an eight-wire connector used commonly to connect devices on Ethernet LANs. RJ-45 connectors look similar to RJ-11 connectors used for connecting telephone equipment, but they are larger.

ST Connector - The ST connector is a fiber optic connector which uses a plug and socket which is locked in place with a half-twist bayonet lock. The ST connector was the first standard for fiber optic cabling. ST Connectors are half-duplex.

SC Connector - The SC connector is a fiber optic connector with a push-pull latching mechanism which provides quick insertion and removal while also ensuring a positive connection. SC Connectors are half-duplex.

LC - The LC connector is just like a SC connector only it is half the size. Like SC

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connectors, LC connectors are half-duplex.

MT-RJ - Stands for Mechanical Transfer Registered Jack. It is a newer fiber optic connector that somewhat resembles a RJ-45 connector. It has a small size, low cost, easy installation, and supports full-duplex.

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EXPERIMENT -12

AIM: To study parts of keyboards and mouse.

THEORY:

A computer keyboard is a hardware device that functions in accordance to the instructions made by the user. It comprises circuits, switches and processors that help in transferring keystroke messages to the computer.

Keyboard connector

Keyboards are generally plugged into the rear of the CPU, on the motherboard, using a purple PS/2 connector, or on USB port.

Parts of Keyboard

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The Keyboard

How a Keyboard Works

When you press a key:

•The keyboard controller detects the keystroke.

•The controller places a scan code in the keyboard buffer, indicating which key was pressed.

•The keyboard sends the computer an interrupt request, telling the CPU to accept the keystroke.

•Operating system responds Controller repeats the letter if held

Different types of a keyboard today

•Wireless

•Corded

•Laptop

•Gaming (Xbox,Ps3, Etc)

•Thumb-Size (Phones, PDA’s, Etc.)

•Numeric

•Virtual

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•Touch screens

Mouse

•The mouse is a pointing device. You use it to move a graphical pointer on the screen.

•The mouse can be used to issue commands, draw, and perform other types of input tasks.

Variants of the Mouse

•Trackballs

•Track pads

•Integrated Pointed Devices

Trackballs

•A trackball is like a mouse turned upside-down.

•Use your thumb to move the exposed ball and your fingers to press the buttons.

Integrated Pointing Devices

•An integrated pointing device is a small joystick built into the keyboard.

•To use an integrated pointing device, you move the joystick.

•These devices provide a set of buttons that function like mouse buttons

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EXPERIMENT -13

AIM: To assemble a PC

THEORY:

Parts :Parts that are to be assembled are as follows :1. Processor (CPU)2. Computer Case3. Optical Drive (DVD RW and SATA capable)4. Memory (RAM)5. Power Supply6. SATA Cables7. Motherboard (SATA Capable)8. Processor Fan9. Case Fan10. Hard Drive (SATA Capable)11. Assortment of case and drive screws

Tools Required :• Screwdriver (for slotted and Phillips head screws) • Wire cutters and strippers • Needle-nosed pliers • Utility knife • Small flashlight • Adjustable wrench • Small container to hold screws • Heat sink compound • Grounding Strap

STEPS :

Step 1: Open The Case

Open the computer case by removing the side panels. Find the screws that hold the side panels in place and remove them. The panel is removed by first sliding it back then lifting it away from the case .

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Step 2: Install Motherboard

Follow these steps to install the motherboard in the case:• Install the I/O bezel plate into the opening in the back of the case . It pushes in from

the inside. • Install standoffs in the case. Check the screw hole locations on the motherboard for

exact placement. • Lower the motherboard into the case and align with the I/O bezel. • Install the screws.

Step 3: Install Hard Drive

The hard drive is the device that stores all of your data. To mount the drive:• Find a 3.5" drive bay to install the drive in. • Slide the drive into place until the screw holes on the sides are lined up with the holes

in the case. • Install the screws.

Step 4: Install Optical Drive

To install the drive:• Slide the drive into the drive bay until the screw holes are lined up and the front of the

drive is flush with the front of the case . Make sure that it is orientated correctly. • Install the screws

Step 5: Install the CPU

To install the CPU:• Find the corner marking that designates pin 1 of the CPU . • Lift the small metal rod next to the socket. • Find the corresponding marking on the CPU socket and insert the CPU so that the

markings are lined up. • Push the rod down to lock the processor in place .

Step 6: Install RAM

The memory is easy to install:

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• Set the RAM board in the socket. Check to see that the notch in the board is in the correct location. If it is not, turn it around 180º.

• Press firmly on both ends of the board to set it into the socket. Make sure the tabs lock into place

Step 7: Install The CPU Fan

To install the fan:• Place thermal compound to the CPU following the instructions provided with the

compound. • Set the fan assembly on the CPU with mounting tabs aligned. • Pull the locking rod down on the fan assembly to lock into place. • Connect the fan assembly's power connector to the motherboard. Consult the manual

to determine proper placement.

Step 8: Install Case Fan

The case fan is usually installed on the back panel of the case. To mount the fan:• Align the mounting holes by holding the fan to the mounting pad on the inside of the

case. The fan needs to be mounted so that it blows air out of the case. • Insert the screws from the outside of the case and tighten

Step 9: Install Power Supply

• Align the mounting holes in the case and power supply. • Insert screws and tighten

Step 10: Connect Cables

With all of the components installed in the case, the jungle of wires can be daunting. It is important to consult the motherboard manual in order to make sure proper connections are made. There are two kinds of connections, power and data.• Every device that has been installed needs power. The motherboard has two power

connections, and there are two connectors specifically for SATA devices (drives). The other connectors will run fans and other non-SATA devices.

• Data cables connect drives and front panel devices to the motherboard. Please consult the motherboard documentation for the exact placement of connectors.

Step 11: Wrap-up

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Now that the components are completely installed, the last thing to do is to reinstall the side panels on the case. The computer is now ready to be turned on and to have software loaded on it. If the computer has problems starting up, check all component connections and mounting to make sure that you have hooked everything up correctly. Consult individual component manuals for specific troubleshooting information if problems persist.

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