Computer Repair I

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The logo of the CompTIA Authorized Curriculum Program and the status of this orother training material as "Authorized" under the CompTIA Authorized CurriculumProgram signifies that, in CompTIA's opinion, such training material covers the contentof the CompTIA's related certification exam. CompTIA has not reviewed or approvedthe accuracy of the contents of this training material and specifically disclaims anywarranties of merchantability or fitness for a particular purpose. CompTIA makes noguarantee concerning the success of persons using any such "Authorized" or othertraining material in order to prepare for any CompTIA certification exam. The contentsof this training material were created for the CompTIA A+ certification exams #221and #222 covering CompTIA certification exam objectives that were current as ofAugust 31, 2001.How to Become CompTIA Certified: In order to become CompTIA certified, you must:This training material can help you prepare for and. pass a related CompTIAcertification exam or exams. In order to achieve CompTIA certification, you mustregister for and pass a CompTIA certification exam or exams.(1) Select a certification exam provider. For more information please visit

http://www.comptia.org/certification/testlocations.htm.(2) Register for and schedule a time to take the CompTIA certification exam(s) at aconvenient location.(3) Read and sign the Candidate Agreement, which will be presented at the timeof theexam(s). The text of the Candidate Agreement can be found atwww.comptia.orglcertification(4) Take and pass the CompTIA certification exam(s).For more information about CompTIA's certifications, such as their industryacceptance, benefits, or program news, please visit www.comptia.orglcertificationCompTIA is a non-profit information technology (IT) trade association. CompTIA'scertifications are designed by subject matter experts from across the IT industry. EachCompTIA certification is vendor-neutral, covers multiple technologies, and requiresdemonstration of skills and knowledge widely sought after by the IT industry.To contact CompTIA with any questions or comments:Please call + 1 630 268 1818or email CompTIA at [email protected]


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CES INDUSTRIES, INC.130 Central Avenue, Farmingdale, New York 11735

CES COMPUTER REPAIR PROGRAMBook I

Table of ContentsI. Safety Lesson

Safety LessonII. Introduction to Computer Repair

1

Lesson 1Lesson 2Lesson 3Lesson 4Lesson 5Lesson 6Lesson 7Lesson 8Lesson 9Lesson 10Lesson 11Lesson 12Lesson 13Lesson 14

Intro to ComputersThe KeyboardThe MonitorThe Power SupplyThe Floppy Disk DriveThe Hard Disk DriveThe MotherboardThe CPU/BIOS/BUSThe RAMThe Video CardThe Multimedia SystemThe PrinterNetwork SystemsComputer Viruses

13233137455767758593103

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Safety LessonObjectives:When you have completed this lesson you will be able to:1. Name the three greatest dangers in working with electronicequipment.2. Prevent accidents by following safe work habits.3. Respond properly in the event of an electrical accident.4. Identify potential risks to equipment, when failing to use ESD(electro-static discharge) procedures.5. Be environmentally aware of the hazardous materials associatedwith computer systems, printers and other peripheral equipment.Discussion:

Most of the electronic devices we use every day, such as TV sets,hair dryers and lamps, are designed to keep you away from thedangerous voltages inside. However, accidents happen! In thislesson you will learn about the dangers of working with electronicequipment using low or high voltages, how to avoid accidents, andwhat to do if an accident happens.There are three main types of accidents, which you must watch outfor when working with electronic equipment.1. Electrical Shock2. Electrical Fire3. Injuries from power toolsIt is strongly recommended that the instructor and students discusssafety in the laboratory before proceeding to use any equipment.

Electrical Shock


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Safety Lesson

sensation. You might be thrown back away from the source of thecurrent. Or you could freeze on the circuit, unable to move Or letgo, stop breathing and go into ventricular fibrillation. This is acondition where your heart cannot keep its rhythm and so cannotsupply your body with the blood you need to live.If you see someone who is receiving an electric shock and isunable to move, you should without touching the equipment or theperson, try to shut off the power as soon as possible. Unplug theequipment or shut it off with a book or other nonmetal object. If youcannot shut off the power, then you must try to disconnect themfrom the equipment as quickly as possible. Do NOT use your barehands to move someone who is in this condition. You may also geta shock. Use a dry blanket or a jacket or other piece clothing toinsulate yourself from the person getting the shock.Check the person for normal pulse and breathing. If they are notbreathing, then call for help immediately. See if there is a doctor or s--nurse, or anyone else with medical training that can help. If youcan't find anyone who can help, then begin artificial respirationwhile someone goes for help. How to give artificial respiration isexplained later in this lesson.Preventing Electric Shock1. Do not use or even touch anything electrical while you are wetor near water.2. Always make sure that electrical equipment is completely offbefore working on it. Unplug the equipment before you work onit and make sure no one can plug it in before you are finishedworking on it.3. Do not operate any electrical equipment with wires hangingloose, protective covers off or safety switches defeated.4. Insert grounded (three prong) plugs into grounded outlets. Donot use 3 wire ground adapters to make them fit into a twoprong outlet.5. Don't use any wires that are damaged or look like they maybreak.6. Disconnect power cords carefully. Do not pull plugs out by the

wire.


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Safety Lesson

Electrical Fires1. Electrical fires are usually caused by short circuits or by anoverload of the circuit that your are connecting the equipment

to. A very large current flows, which overheats the equipmentand starts the fire. Never touch any equipment that is burning orsmoking. Shut the power off as quickly as possible, but nevertouch the equipment.2. Never throw water or use a water filled fire extinguisher on anelectrical fire. You may get a shock or even make the fire worse.Only use a fire extinguisher that has been rated for use on liveelectrical equipment, the NFPA (National Fire Protection

Agency) designation of Class 'C' indicates that it is approved foruse on live. electrical equipment. The most common fireextinguishers found in most shops or laboratories will be triclass (AB&C) or may be only 'BC' either way, if the letter 'C' isin the class designation, it is safe and proper to use.There are three types of extinguishers, which are good to useon electrical fires.They are:a. Carbon Dioxide - This is a class 'BC' extinguisher and may

be used for electrical as well as flammable liquid (Gasolinetype) fires.b. Dry Chemical - This type extinguisher may be a tri-c1ass or'ABC' type or may be only a 'BC' type extinguisher, andwhile it will definitely handle a fire in an electronics orcomputer repair shop, it will destroy any equipment beyondrepair that you spray with it. Therefore, is not recommended

for use in electronics or computer repair type shops.c. Halon Gas - This is a class 'BC' extinguisher and may beused for electrical as well as flammable liquid (Gasolinetype) fires. It will not destroy the electrical or electronicequipment that it is used on. However, halon has fallen outof favor due to the fact it is a CFC (chlorofluorocarbon) typegas, which is known to affect the ozone. layer.Tools used in electronicsMost tools used in electronics are safe, if they are used properly.Screwdrivers, knives, wire cutters, and other sharp tools should be


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Safety Lesson

Don't throw or play with tools.Make sure a tool is in good condition before you use it. Checkhammers before use to make sure the head is attached tightly tothe handle. Make sure that power tools have good cords on themand that all the safety shields are properly attached. When usingdrills, saws, or other power tools, clamp your work down beforestarting. Keep your fingers away from moving parts, and alwaysuse eye protection.Don't leave power tools lying around plugged in when you are notusing them. Soldering irons are especially dangerous and cangive someone a serious burn. Unplug your soldering ironimmediately after you are done using it and don't leave it before itcools off. Just think of what a tool that can melt metal can do tosomeone's skin.Minor Injuries:If someone receives a minor cut or burn, it should be washed incold water immediately. Get medical help as soon as possible.If a major injury occurs and someone is bleeding heavily from anarm or leg, try to slow down or control the bleeding by applyingdirect pressure to the injury. If possible elevate the injury to reduceor stop the flow of blood. Observe universal precautions aboutexposure to blood and body fluids by having rubber or latex glovesin the shop, so that you can protect yourself from diseasestransmitted by blood and body fluids.

Artificial RespirationAlways check for a pulse and see if the victim is breathing. If theyhave a pulse and they are breathing DO NOT start artificial respirationor CPR. Have someone call for professional medical assistance.

Artificial RespirationBegin immediately to use artificial respiration if the victim is notbreathing:a. Turn the victim on his or her back.b. Clean the mouth, nose, and throat. If they appear clean, startartificial respiration immediately. If foreign matter is present,wipe it away quickly with a cloth or your fingers.


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Safety Less.on

d. Hold the lower jaw up. (Insert your thumb between the victim'steeth at the midline - pull the lower jaw forcefully outward so thelower teeth are further forward than the upper teeth. Hold thejaw in this position as long as the victim is unconscious).e. Close the victim's nose. (Compress the nostrils between yourthumb and forefinger).

f. Blow air into the victim's lungs. (Take a deep breath and coverthe victim's open mouth with your open mouth, making thecontact air-tight. Blow until the chest rises. If the chest does notrise when you blow, improve the position of the victim'spassageway, and blow more forcefully.g. Let air out of the victim's lungs. (After the chest rises, quicklyseparate lip contact with the victim, allowing him or her toexhale.)h. Repeat steps (f) and (g) at the rate of 12 to 20 times perminute. Continue rhythmically without interruption until thevictim starts breathing or professional assistance arrivesElectro-Static Discharge and Damage toElectronic EquipmentElectro-Static Discharge or ESD can permanently damage ordestroy the electronic components that are used with all personalcomputers. It is possible that on a dry day, the act of walkingacross a carpeted floor with rubber sole shoes can produce a staticcharge of several thousand volts of electricity. While this electricitylacks the current or force to do any physical harm to a healthyhuman, the charge can be lethal to the computer. It becomesabsolutely necessary to use the proper techniques to preventdamage to the computer from ESD. Following a few simple rulesearly in your course of study, will help prevent accidents in thefuture.Basic ESO (electro-static discharge) Protection ProceduresProper Procedures for ESD protection: In order for damage to takeplace from ESD, the voltage and small current must pass through acomponent or components on the computers main board or on anyof the associated circuits contained in the computer. When theelectrical charge passes through a component, the voltage and


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Safety Lesson

are becoming smaller each day I with the average size of aninternal component being .8 microns in size. The ESD charge issimilar to dropping a bomb on the middle of an active runway. Toprevent the ESD from damaging a computer, the followingprocedures should always be followed.A. Always unplug the computer from the electrical supply.While some technicians will argue that keeping the computerconnected to the AC (alternating current) outlet allows for adirect connection to the AC ground, more computers have beendamaged by accidentally inserting or removing an expansioncard or component with the power on.B. Always wear and properly use, an approved ESO GroundStrap. The ESD ground strap will protect you and theequipment from developing any electrical charges that candamage the computer. It is very important that you use aGround Strap that is an ESD approved ground strap and notsimply a piece of wire that you attach to your wrist and toground. The approved ground strap will discharge theelectrostatic charge with out connecting you directly to ground.Thus any problems that may be associated With the computer

or any peripheral you may be working on, will not cause you tobecome part of the electrical circuit and potentially electrocuteyourself in the process.C. Always use an electrostatically protected work surface ormat. This prevents the build up of static electric charges. Thework surface should be ESD protected. While this may not bealways possible when performing a field repair, good staticprotection procedures will prevent damage to a computer.D. Always touch the bare area of the computer case beforebeginning the repair. ESD can only occur when there isadifference of potential or a voltage difference between thetechnician and the computer. Touching the case equalizes thischarge.E. When removing parts and components from the computer,always place them on the anti-static surface. Wheneverpossible use an anti-static mat that is properly grounded toprevent damage to the component or c o m p o n e n t ~ , removed

from a computer. If an anti-static mat is not available, be sureto use a clean area, free from any scraps of wire, aluminum foil


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Safety Lesson'

Caution: Some tec;hnicians will use aluminum foil instead ofan antistatic mat to place components on. This is a verydangerous process. Most main boards contain a battery,either lithium or nickel-cadmium, both of which can explode i fthey are shorted. Placing the board onto aluminum foil willshort the battery terminals and may result in an explosion,possible fire orpersonal injury.1. The Computer Power SupplyWhile the output of the supply is a low voltage between 5 and12 volts, the input voltage is directly connected to the ACline.This voltage is 120 VAC (voltsAC) at currents as high as thecircuit breaker feeding the outlet. In a business environment,the current to an individual outlet may be as high as 30 amps.Once a cover is removed from the power supply, the technicianmay be exposed to voltages and currents that can injure or kill.Field technicians rarely, if ever, will repair a power supply onsite. They will simply replace it and or repair it back in the shop.2. The Computer MonitorThe computer monitor is basically a television monitor and assuch, has the same type of circuitry inside it. The Picture Tube

or CRT (Cathode Ray Tube), is a fragile glass envelope, that isunder a high vacuum, and if dropped, the tube can implodeviolently causing pieces of glass to fly in all directions. The CRTalso stores an electrical charge, due to the construction of theCRT, it is possible for the tube to hold a charge for severalmonths. This charge can be several hundred to severalthousand volts. The most common monitors, 14" and 15"CRT's usually have a charge of 20 to 25 thousand volts appliedto them. In addition to the CRT and its associated ability tostore an electrical charge even when not turned on or pluggedin, the monitor itself operates on voltages significantly higherthan those found inside the average personal computer. Normalpower supply voltage for a monitor is between 120 and 180volts, with special power supply voltages of 400 to 1600 voltsfor deflection coils, and focus circuits. If you are not specificallytrained in the service or repair of monitors and their associateddangers, do not open the back covers.

3. The Laser PrinterLaser printers utilize a process similar to a photocopy processand as such, use a series of charging wires called Corona


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Safety Lesson

fuser roller to permanently fix the image on to the paper. Theserollers operate at temperatures as high as 195 degrees Celsius.The rollers are under high pressure from springs that maintain aconstant pressure on the rollers surface and may be as high asseveral hundred pounds, depending upon the printer. Theimaging process involves the use of laser light; this laser lightutilizes the infra-red spectrum, and as such is invisible. Whilethe output of the laser is only a few milliwatts or 1000 times lessthan a conventional night-light, it is still possible, especially ifthe light source shines directly into the eye, to cause damage tothe eye. Therefore, when working on a laser printer, one shouldnever bypass any safety interlocks associated with the safeoperation of the printer, and most importantly, if you are nottrained to repair the printer, you should not attempt it.

4. Dot Matrix PrintersA dot matrix printer like any printer has moving parts, whichpose a pinch risk to fingers, hair, ties and any other object thatmay get in the way of the moving print head. The print head,when printing for sustained periods of time can become veryhot, and cause severe burns on contact with exposed skin.5. Ink-Jet PrintersAn Ink-Jet or Bubble-Jet Printer has the same moving partshazards as a dot matrix printer, however it does not have a printhead that can become hot enough to burn skin. The majorsafety risk from an ink-jet printer is to the work area and thetechnicians clothing. The inks stain very quickly, and arenormally not water-soluble, it is possible to go around with theresults of your repair for weeks, after spilling the ink on yourhands or cloths, not to mention the customers white carpet.6. Phone ModemsIn addition to ESD precautions, the phone modem presents thetechnician with the distinct possibility of a nasty shock if notdisconnected from the phone jack. The phone network normallyoperates with an operating voltage of -48 volts DC. When all thephones connected to the same line as the modem, are on thehook or hung up, this -48 volts is enough to give the techniciana mild buzz, if they should happen to connect directly across thered and green phone lines. If the technician should happen to

be lucky enough to be touching the phone line when it rings, thevoltage on the line jumps up as high as 98 to 140 volts AC while


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Safety Lesson

disconnect the modem from the phone line before performingany repair to a computer equipped with a modem.7. Uninterruptable Power Supplies [UPS]

These power supplies use batteries to produce AC output. Thesame type of AC current that is available at a normal householdor business outlet. The voltages available at the output of aUPS are lethal. Most UPS models can produce 120 v o l t ~ at upto 20 amps of current. In addition the voltage is present even ifthe power to the building or outlet is off. The batteries in a UPSwillcause a fire or severe burns if they are shorted in any way.Treat a UPS with the same respect as an outlet, even thoughthe unit is working on a battery.Disposal procedures for batteries, cathode ray tubes and otherenvironmentally sensitive items1. Nickel-Cadmium batteries. These batteries while rechargeableseveral hundred times, do have a finite life span. When thistype of battery is "dead" and can no longer be recharged, itshould be recycled and not disposed of in the general wastestream. Cadmium is a dangerous heavy metal compound thatcan pollute ground water if not properly disposed of.2. Lithium, Lithium-Ion batteries. While these batteries are not asdangerous to the environment as the Nickel-Cadmium battery,they should be recycled whenever possible3. Lead-Acid, Sealed Lead-Acid or Gel Cell type batteries. All ofthese batteries contain lead, which must be recycled.4. Laser Printer Toner Cartridges, these cartridges have a givenlife span, if they are not being recharged and reused, theyshould be recycled for the many parts that are contained withinthe cartridge. Most manufactures of printer or personal copiercartridges have some type of recycling program available toreturn the old used cartridge directly to the manufacturer forrecycling.

In general, for all disposable items, check with local ordinancesregarding the availability of and requirements for recycling andthe disposal of batteries, office waste, and possibly hazardousmaterials.


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Safety Lesson

Proper steps to safely discharge a Cathode Ray Tube(When applicable)As previously discussed, the CRT is capable of holding asignificant electrical charge for long periods of time. It is necessaryto discharge the CRT before performing any work on the monitor orCRT. The following procedure is a safe and correct method ofdischarging the CRT.1. Turn the power to the monitor off, and remove the AC line .cordfrom the outlet.2. Using a wire with a series resistor and alligator clips on both

ends, clip an end to a non-painted chassis portion of themonitor.3. Place one hand behind your back so that there is no possibleway to complete a circuit while discharging the CRT.4. Clip a small insulated screwdriver to the free end of the wire5. Locate the "Second Anode Connection" this is the connectionthat contains the high voltage wire, that is normally at the top ofthe CRT and is usually Red.6. While keeping your one hand behind your back, slowly insertthe screwdriver under the protective rubber boot of the secondanode connection. It is possible at this time that you may hearsome snapping or crackling sounds, this is normal. Allow thescrewdriver to remain in contact with the second anodeconnector for a minimum of 2 minutes to insure that the highvoltage has been discharged.7. Remove the screwdriver from under the cap.8. Remove the second anode connector by carefully squeezingthe connector together and lifting the connector slowly up andaway from the CRT.9. At this time the CRT is completely safe to handle as far as anyhigh voltage shock is concerned. Remember that the CRT isunder an extremely high vacuum pressure and a crack in theglass may result in a violent implosion of the tube.


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Safety Lesson

Assignment:Answer the following multiple-choice questions:1. Which type of accident happens when working with electronicsequipment?a. Electrical Shock.b. Electrical Fire.c. Injuries from power tools.d. All of the above.2. Electrical Shock is what happens when an electric current flowsthrough your body.a. True.b, False.3, Electrical fires are usually caused by short circuits or by anoverload of the circuit that you are connecting the equipment to,a. True.b. False.4. Which one is a type of fire extinguisher used on an electrical fire?a. Carbon Dioxide.

b. Dry Chemical.c. Halon Gas.d. All of the above.5. Artificial Respiration is used if the victim is not breathing.a. True.b. False.6. Electro-Static Discharge can permanently damage or destroy the

electronics parts that are used with all personal computers.a, True.b. False.7. Which one is an ESD protection procedure?a. Always plug in the computer to the electrical supply.b, Always use an electro-statically protected work surface or mat.

c. Always wear an ESD Ground Strap.d. Both band c.


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Safety Lesson

8. Which is a basic ESD protection device?a. ESD approved ground strap.b. Aluminum foil.c. Both a and b.d. None of the above.


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Introduction toComputersObjectives:When you have completed this lesson, you will:

Lesson 1

1. Be able to assemble the CES 975 Computer Repair Trainer into aworking computer.

2. Use the CD-ROM Drive to access the "How Computers Work"program in Windows 98.3. Understand the special turning-off procedure for Windows.

Materials Needed:1. CES Computer Repair Trainer Model CES 975.2. CES Computer Repair Module Manual.

. , Po\O/ER SUPPLY .ISCONNECTED TO EACHAND EVERY MODULEPOWER r - - CD ROMSUPPLY

MONITOR!EXPANSION KEYBOARDlU

SLOTS CONNECTORI: RAM ~ IEMORYMODULESMOTHERBOARD

HARD FLOPPYIcPul C ~ f r t 1 E ( 1

DISKDISK KEYBOARDEMORY


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Lesson 1

Discussion:

Introduction to Computers

1. The personal computer industry has become one of the fastestgrowing areas of technology today. This caused an . increasingneed for trained computer repair technicians in the job market. Acomputer repair technician must have a complete understanding ofall of the hardware, programs, peripherals, and in some cases anunderstanding of networks and communications.This module is designed to provide the basic knowledge andunderstanding of the personal computer, its functions, operations,components and software. Only then can we begin to work on theskills and procedures necessary to service, repair, maintain an(jtroubleshoot the personal computer of today.The main objective of each experiment in this computer repairmodule is to introduce you to the function of each of the majorcomponents of a personal computer. They will familiarize you withthe proper operation as well as discuss the symptoms associatedwith a failure and teach basic troubleshooting skills. Since this is amodular program, the intention of this program is not to. actuallytake the computer apart and physically change the defectivecomponent, but to help you learn how to "successfully" completethe repair. This course will not get involved with the "setting up" of apersonal computer. Simply put, we assume that the computer thatyou are working on was already built, and did work at one time.Setup procedures for advanced operation such as CMOS(Complimentary Metal Oxide Semiconductor) configuration orsoftware configurations will not be covered in thismodule.

Each lesson that you are about to start will begin with a discussionof the topic, followed by a specific procedure that you are tocomplete. A fault or trouble is inserted into the computer, followedby a discussion of the proper repair procedure associated with thatfault.


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' " POVERSUPPLY ISCONNECTED TO EACHAND EVERY MODULEPOWER CD ROMSUPPLY

J MONITOREXPANSION K E ' I B O A R D ~ [ JSLOTS C O N N ~RAMMEMORYMODULESMOTHERBOARD -

HARD FLOPPY I ] ~ ! ~ ~ ' 1 DISKDISK KEYBOARD2. The personal computer is a modular system, consisting of manyseparate components that when connected correctly function as acomplete computer.3. Proper troubleshooting skills require the proper tools. The toolsmost often used by a technician in the field, consist of a good

magnetic screwdriver and an anti-static wrist strap. Someprofessionals will cringe at the thought of using a magneticscrewdriver anywhere near a computer. They believe that damagecan be done to the disk drives inside the computer. In fact, the onlydamage that you can cause is erasing a floppy disk if youaccidentally place the screwdriver directly on top of the disk. It ispossible to magnetize an area of the computer monitor and causethecolor purity to be effected if the screwdriver comes too close tothe monitor. A good general rule when working with a magneticscrewdriver, is to keep it in your pocket when you are not using it toremove screws.

Lesson 1

4. Anti-Static ProtectionWhenever you work on any electronic equipment, the possibility ofdamage from static electricity is great. The simple act of walkingacross a nylon carpet, can cause your body to develop a staticcharge of several thousand volts. The charge, if discharged into acomponent of the personal computer, will most certainly damage,ifnot destroy the component. To prevent this from happening, goodanti-static protection should be used.


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Lesson 1 Introduction to Computers

correctly if it is connected to a proper ground. In addition, wheneverworking on a computer system, most technicians will keep the ACpower cord connected to the AC outlet, thereby maintaining aconnection to ground to aid in static protection.If your instructor is uncomfortable with keeping the AC cordplugged in while you are working on the computer, a wire withalligator clips on both ends can be attached to the frame of thecomputer and to the faceplate of the outlet, which will also providestatic protection.

Procedure:1. Please locate the following components to the CES ComputerRepair Module Model CES 975:

A. CES Computer Repair Trainer Model CES 975B. Power Cord for the Computer Repair TrainerC. Monitor (with power cord and cable)D. MouseE. KeyboardF. Printer (with printer cable)G.CO-ROM "How Computers Work"H. Stereo Headphone JackI. Blank 3 %" disk

2. Connect the cable from the monitor to the video adapter that is onthe right side of the CES Computer Repair Trainer.3. Connect the keyboard cable to the keyboard connector.4. Connect the mouse cable to the mouse connector.5. Connect the computer power cord to the power supply on thetrainer.6. Connect the printer cable to the printer and to the computer trainer.7. Connect the headphones to the headphone jack, which is located


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8. Plug the computer power cord, the monitor power cord, and theprinter power cord into the outlet.9. Turn the monitor power switch to the "on" position now. Wait a few

seconds until the monitor warms up and then proceed.

Lesson 1

10. Turn the main power switch of the CES Computer Repair Trainer tothe "on" or up position now.With the "ATX" style computer, the main power switch is located onthe power supply, when the mainpower is on, the user must turnthe computer on by depressing a momentary switch located at theback of the trainer.With the "AT" style computer; the main power is turned on by only alarge toggle switch located at the back of the trainer.The Computer is now going through the standard boot-upprocedures. In about 30 seconds, you should see a blue screen.This is the normal start-up screen for Windows 98.At this time it is very important to learn the proper procedure forturning the computer off. This is commonly referred to as theshutdown procedure.

COMPUTER SHUT-OFF INSTRUCTIONS:Since the computer repair system uses Windows as its operatingsystem, it is very important to use the correct procedure whenturning off the computer.Failure to use the proper shut-off procedure may result inpermanent damage to the computer.A. Using your mouse, click once with the left mouse button onthe start box in the lower left hand corner.B. Move the mouse cursor to "Shut down" and click the leftmouse button once.C. The computer will ask, "What do you want the computer todo?" Make sure "shutdown" is selected and click on "OK"..With the "ATX" style computer, the computer will shutdown onit's own.D. With the "AT" style computer, the computer will tell you "It's


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You have just properly turned off the computer. To continue thelesson, please re-start the computer now.For the balance of this lesson, you will be using the CD-ROM"How Computers Work".

11. Before continuing with this experiment, you will notice that there isan expansion card installed in the computer that has two sevensegment displays. This is called a POST Diagnostics Card.The purpose of this card is to interpret information that is sent fromthe BIOS (Basic Input Output System) during the startup or bootprocedure. During the start up or boot procedure,a specialprogram called the Power On Self Test or POST is automaticallyexecuted. This program will test the various major componentsand determine if they are present, and if they are present, are theyworking correctly.

12. Each test that the POST will execute has a unique numberassociated with the test, this number is sent out on the expansionbus as each test is started. If you have the special hardwarerequired to read this information, the code numbers will bedisplayed. When a component or device fails, the code that isdisplayed is the number that represents the test that has just beenstarted. A list of these test codes can be obtained from. themanufacturer of the main board. With this information, it is possibleto determine what test has failed, and therefore, a course of actionin repairing the system.Each machine will have different internal code numbersrepresenting the various steps within the POST program. You.maynot always have the correct code available for the system that youare servicing and unfortunately these codes can change frommotherboard to motherboard manufactured by the same company.

13. Before continuing this experiment, note what number is displayedon the POST Card Display, NOW. The number displayed is theNORMAL or WORKING state of this individual computer, and willbe displayed each and every time the computer is started andsuccessfully completed the POST.14. The CD-ROM drive is located on the right side of the trainer. Openthe CD-ROM tray by pressing the button on the right side of the


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15. Insert the CD-ROM "How Computers Work" into the drive with thelabel facing up. Do not touch the bottom surface of the disk.16. Close the CD-ROM tray by pushing the button again.17. Put on your stereo headphones.Plug the headphones into the jack on the right side of the trainernear the key switch.18. Use the mouse to double click on the icon "HowComputers Work".(Left button)19. If a warning occurs on the screen, click on "OK".20. You are about to go on an overview tour ofthe computer.Move the mouse cursor to 'Tours" and click once.21. Now, move the mouse to "overview" and click once.This multimedia presentation should last approximately 12 minutes.

Sit back and enjoy III22. When the final "Run a Program" section is finished, click on "Main".23. Now click on "Exit" to exit the program.24. Click on "OK" when asked "Are you sure you want to leave?"25. Click on "'OK" again.You have just exited the multimedia program.

Lesson 1

Review:CPU - stands for "Central Processing Unit". It handles and controlsall input and output of information.Multimedia - is the merging of video and audio, and program files toproduce a presentation.Bootup - is the process of powering up a computer system. It looksfor certain start-up instructions, which are stored on chips, such asthe BIOS chip.Formatting a disk - it puts information on the disk so that the


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I/O device - stands for Input andOutput devices such as:1. Keyboard (input device)2. Floppy Disk Drive (input or output device)3. Printer (output device)4. Monitor (output device)5. CD-ROM (input or output device)6. Hard Disk Drive (input or output device)Memory/Storage - the Computer has two ways to store information.1. Memory or RAM (Random Access Memory)2. Disk Drives (Hard or Floppy)Run a Program - the process by which the computer loads aprogram into the memory, then follows the instructions contained inthe program to perform a given task, such as running themultimedia disk - "How Computers Work".

Assignment:Answer the following multiple-choice questions:1. The CPU:

a. Handles the input and output of information.b. Performs basic arithmetic (math) functions.c. Means Central Processing Unit.d. All of the above.

2. During the boot-up process, the computer checks to see if a:a. A boot disk is available.b. Video card is installed in the computer.c. Keyboard is plugged into the keyboard connector.d. All of the above.

3. The BIOS ROM Chip tells the operating system:a. What hard drive type is installed and how to.interact with it.b. What video card is installed.c. How much RAM memory is installed.d. All of the above.


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4. Which one is just an output device?a. Keyboardb. Disk Drivec. Printerd. Mouse

5. Which one is just an input device?a. Disk Driveb. Keyboardc. CD-ROMd. All of the above6. How many ways can the computer store information?a. Twob. Onec. Sixd. Four

7. What does RAM stand for?a. Random Access Memoryb. Random And Memoryc. Read Only Memoryd. Random Write Memory

Lesson 1

8. Which type of storage devices does the computer use as its mainstorage device?a. Floppy Driveb. Hard Drivec. CD-ROMd. All of the above

9. Formatting a disk means that the computer's operating system,puts disk information and instructions on a hard drive or floppy disk,so that the operating system knows where the information isstored, what information is stored and how much free space isavailable on the disk.a. Trueb. False10. Multimedia is the merging of video and audio files to produce a

presentation such as the presentation that you have just seen andheard in this lesson.


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The KeyboardObjectives:When you have completed this lesson, you will:1. Understand how the keyboard works.

Lesson 2

2. Understand how the keyboard communicates with the system unit.3. Be able to locate and identify a common fault associated with thekeyboard.Materials Needed:1. CES Computer Repair Trainer Model CES 975.2. CES Computer Repair Module Manual.

Discussion:1. The keyboard that is used with the personal computer is nothingmore than a group of switches that have been arranged into acombination of rows and columns. The keyboard is connected tothe motherboard by way of a 5 conductor cables and connectors,which is connected to the keyboard input on the motherboard.2. The five conductor cable includes the following signals:

a. Power (+5 Volts)b. Groundc. Serial Data out to the motherboard


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Lesson 2 The Keyboard

Inside the keyboard

3. The keyboard utilizes a plunger attached to each of the mechanicalkeys that press against the contacts to form a complete electricalcircuit.4. Inside the keyboard is a micro-controller or simply a small computerthat has only one task to accomplish. The micro-controllerconstantly looks at each of the individual keys through a processcalled scanning. When a key is pressed, the microcontroller theninterprets the key press into what is called the "key scan code".The scan code is a numerical representation of what key waspressed. The scan code consists of two parts for each key on thekeyboard, the scan code that represents a key down, or when you

pressed the key and a scan code that represents a key up, or whenyou released the key.5. This information is then converted into a serial data stream andsent to the computer system by the keyboard microcontroller. Thekeyboard controller on the motherboard converts the serialinformation coming from the keyboard. It then signals the CPU(Central Processing Unit) by way of the interrupt control systemthat there is keystroke information to be processed. The CPU is

interrupted from the task or program that it is currently doing toservice or process the interruption, in this case, the interruption isthe keystroke or keystrokes you typed on the keyboard.Equipment Setup Procedures:

If your Computer Repair trainer has not been setup, ask yourteacher for the equipment setup procedure sheet before beginningthe following procedure.


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The Keyboard

Procedure:1. Open the CD-ROM tray.2. Insert the CD-ROM "How Computers Work" into the Drive.3. Close the CD-ROM tray.4. Put on your stereo headphones.5. Use the mouse to double click on the icon "How Computers Work".6. When a warning occurs on the screen, click on "OK".

Lesson 2

7. When the music starts and the title screen appears move themouse cursor anywhere on the screen and click once using the leftmouse button. This will help the user to quickly start the programby bypassing the title screen and make the music stop playing.8. You are about to go on a tour of the Keyboard.Move the mouse cursor to the picture of the Keyboard on the

monitor and click once.Sit back and enjoy II!

9. After you have listened to the description of the Keyboard, movethe mouse cursor to the back of the computer and click once.10. Now move the cursor to the "Keyboard Port" and click once.

Sit back and enjoy ,!!11. When the tour of the "Keyboard Port" is finished, click on "Main" togo to the main menu.12. Click on "Exit" to exit the program.13. Click on "OK" when asked "Are you sure you want to leave?"14. Click on "OK" again.You have just exited the multimedia program.


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Lesson 2 The Keyboard

Computer Repair and Fault Insertion:IFault Insertion I1. Please follow the correct procedures in turning the computer repairtrainer "OFF".COMPUTER SHUT-OFF INSTRUCTIONS:

Since the computer repair system uses Windows as its operatingsystem, it is very important to use the correct procedure whenturning off the computer.Failure to use the proper shut-off procedure may result inpermanent damage to the computer.A. Using your mouse, click once with the left mouse button onthe start box in the lower left hand corner.B. Move the mouse cursor to "Shut down" and click the leftmouse button once.C. The computer will ask, "What do you want the computer todo?" Make sure "shutdown" is selected and click on "OK".With the "ATX" style computer, the computer will shutdown onit's own.D. With the "AT" style computer, the computer will tellyou "It'snow safe to turn off your computer".E. Turn the computer OFF.F. Ask your instructor for the key to the key switch located on the

right side of the trainer.G. Insert the key and rotate the key to a horizontal position.

2. Move fault switch to position one.This will insert a fault in the keyboard system.3. Turn the power to the computer repair trainer on.

ISYMPTOM I4. Does the computer repair trainer start normally?


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The Keyboard

5. What symptoms did you observe?You should have observed that Windows does not start normallyand that an error message has occurred on the screen. ThePOST(Power On Self Test) detected that there is a failure of a majorsystem associated with the keyboard, and has detected the error.You should notice that the POST Card in the computer hasdisplayed a different code other than the normal boot or start-upcode.IDIAGNOSISI

6. Based upon these observations, there is a number of possiblethings that can be wrong with the computer.

Lesson 2

The keyboard may be defective.With the type of error that you have identified, the keyboard wouldmost likely be the problem associated with the fault observed.Keyboard failures can occur for numerous reasons, with the mostcommon being a foreign substance like coffee, being spilled ontothe keyboard.The keyboard cable may be defective.A crimp or other physical damage to the keyboard cable can alsogenerate a keyboard error. Even though the POST has identified akeyboard error, it does not indicate whether the fault is thekeyboard or its associated components.The keyboard port on the motherboard may be defective.The keyboard may be functioning 100 percent correctly, .but isunable to communicate with the keyboard controller on the mainboard. This type of problem may be caused by a small 1 amp fuse,located near the keyboard connector, that provides 5 volts to thekeyboard via the keyboard cable.The keyboard controller may be defective.The. microcontroller in the keyboard may no longer be functional.The motherboard may be defective.When all other devices have been. tested, and you have changedthe components that are easy and the least expensive to change,the only other cause for a keyboard error can be the motherboard


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Lesson 2

IREPAIR IThe Keyboard

The keyboard is defective.Replace the keyboard, and re-test the computer to see if theproblem has been solved.The keyboard cable may be defective.Even if you determine that the problem is the keyboard cable, thecable is part of the keyboard. The normal repair procedure is toreplace the keyboard.The keyboard controller may be defective.It is impossible to obtain the exact microcontroller used in thedefective keyboard. The repair is to replace the keyboard.The motherboard may be defective.After changing the keyboard, you have determined that thekeyboard error is still present. The most iikely failure would thenbe, associated with the keyboard circuitry located on themotherboard. The repair procedure for the symptoms stated is toreplace the defective motherboard.Repairing Procedure:1. Since this fault prevented the computer from startingnormally, there is no need to follow a special shut-downprocedure.2. Turn off the main power switch now.3. Turn fault switch to the original"No Fault" position and turnthe key switch to original vertical position.4. Your computer is now ready to proceed with the next lesson.

Review:You should have observed that the computer was unable to startnormally. The Windows startup screen never appeared. Thecomputers internal diagnostics program known as the Power OnSelf Test or POST for short, detected that the computer had adefect that was detectable by the diagnostic program. The programresponded with an error message that corresponded to the defect


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The Keyboard

Assignment:Answer the following multiple-choice questions:

Lesson 2

1. When pressing the letter K down on the keyboard, the plungerpresses against two electrical contacts to form a circuit.a. Trueb. False

2. What chip is used first by the computer to decide which key on thekeyboard was pressed?a. RAMb. CMOSc. Microprocessord. 810S

3. The RAM does not hold the scan code until the computer is readyfor it.a. Trueb. False

4. The CPU chip is used in the keyboard decision-making process.a. Trueb. False

5. What is the last chip used in the key decision making process?a. CMOSb. Keyboard controllerc. CPU 'd. 80th A and 8

6. How many types of keyboard ports are there?a. Oneb. Twoc. Threed. Four


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The MonitorObjectives:When you have completed this lesson, you will:1. Understand how the monitor works.

Lesson 3

2. Understand how the computer system communicates with themonitor.3. Be able to locate and identify a common fault associated with themonitor.Materials Needed:1. CES Computer Repair Trainer Model CES 975.2. CES Computer Repair Module Manual.

Discussion:1. The monitor can be thought of as a specialized television screen.

In fact, most of the circuits and components that are associatedwith the modern color television system, are very similar to thecomponents that are in the computer monitor.


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Lesson 3 The Monitor

2. The major difference between the television and the computermonitor is that the television is able to tune or select differentchannels and has audio circuits that allow the program audio to beheard. The computer monitor accepts the information to bedisplayed by way of the video card installed on the motherboard.The video signal is an analog signal that contains the color,synchronization signals and intensity signals. The monitorinterprets these signals and displays the information that you seeon the screen.

3. There are many different types of monitors, and the type of monitorthat you use must agree with the type of video card that you haveinstalled on the computer. The four types of monitors that you maycome across are: Monochrome or single color, often green or orange screenmonitor. CGA or Color Graphics Array monitor. EGA or Enhanced Graphics Array monitor. VGA or Super VGA (SVGA), video graphic array monitors. TheSVGA monitor is the current and the most common type ofmonitor.

Equipment Setup Procedures:If your Computer Repair trainer has not been setup, ask yourteacher for the equipment setup procedure sheet before beginningthe procedure below.Procedure:1. Open the CD-ROM tray.2. Insert the CD-ROM "How Computers Work" into the Drive.3. Close the CD-ROM tray.4. Put on your stereo headphones.5. Use the mouse to double click on the icon "How Computers Work".6. When a warning message occurs on the screen, click on "OK".


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The Monitor

7. When the music starts and the title screen appears, move themouse cursor anywhere on the screen and click once using the leftmouse button. This will help the user to quickly start the programby bypassing the title screen and make the music stop playing.8. You are about to go on a tour of the Monitor.Move the mouse cursor to the picture of the Monitor and click once.

Sit back and enjoy III9. When the tour of the Monitor is finished, click on "Exit" to exit theprogram.10. Click on "OK" when asked "Are you sure you want to leave?"11. Click on "OK" again.You have just exited the multimedia program.Computer Repair and Fault Insertion:IFault InsertionI1. Please follow the correct procedures in turning the computer repairtrainer "OFF".2. Move the fault switch on the side of the monitor to position one.This will insert a fault in the monitor sub-system.3. Turn the power to the computer repair trainer on.

ISYMPTOM I4. Does the computer repair trainer start normally?You should notice that the computer will start normally, howeverthe information that is being displayed on the monitor appears to bescrambled, somewhat like a cable television station that you arenot paying for.Depending on the type of monitor used you may see diagonal linesor a blank screen. If the screen is blank, it is because you areusing a "green monitor". A green monitor blanks out when no video

Lesson 3


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switch to position number 1. As you rotate the switch, observe thediagonal lines on the screen before it blanks out.5. What symptoms did you observe?

You should have observed, that the computer repair trainer didboot in the normal fashion, as indicated by the post display card onthe trainer, however, it appears that the video information on themonitor is scrambled, for a few seconds and then the monitor goesblank (black).6. Based upon these observations, there are a number of possiblethings that can be wrong with the computer.

The video card may be bad. The cable to the monitor may be bad. The monitor itself may be bad.The interesting part about troubleshooting computers is thatsurprises happen to the best of us. What you have just experiencedis what happens when the monitor you are using has a featureknown as a green feature. The green feature is an energy savingfeature that the manufactures have installed in accordance withrecommendations from the EPA (Environmental ProtectionAgency) to save energy. Whenever a monitor is not in use for a fewseconds, that is a loss of a video signal from the computer, themonitor turns off. What is happening with this fault is that since thevideo signal has been lost from the host computer, the monitorassumes that the user has turned off the computer but forgot toturn off the monitor, so it shuts off.IDIAGNOSISI

7. Based upon these observations, you would diagnose the monitorproblem as follows.Defective Video CardSince the computer appears to be starting normally, and at thistime there is no error code displayed on the Post Card, it ispossible to assume that the video card is functioning correctly. Asdiscussed in previous experiments, the POST program will onlydetect a problem associated with primary hardware, and a failurethat the POST diagnostic program is aware of. Since the computer


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The Monitor

"replacement", it does not hurt to try changing the video card. Forthis fault, the problem would remain.Defective Monitor CableSince the monitor cable carries all the information to the monitor forvideo, synchronization, intensity and color, it is a possibility for theproblem to be associated with the monitor cable. A quick,disconnect and reconnect of the cable, or a swap with a knownworking cable will verify if the cable is indeed the cause of this fault.Defective MonitorIf, after swapping the cable and the video card, the problem stillexists. The cause of the difficulty is in the monitor. For this youwould replace the monitor, since the repair of the monitor requiresmore technical skill and a familiarity with television circuits.IREPAIR IThe problem associated with the computer repair trainer is aproblem in the monitor circuitry itself. Since the monitor is aspecialized television set, repairing the monitor requires thecomplete understanding of how video, color and synchronizationcircuits function. Most field repairs involving monitors are resolvedby changing the defective monitor with a known good monitor andsending the monitor back to the manufacturer for repair.Repairing Procedure:1. Since this fault did not prevent the computer from startingnormally, but the fault was not in the computer system itself,you can remove the fault by turning the Monitor fault switch

to the original "No Fault" position,2. Your computer is now ready to proceed with the next lesson.

Review:The computer monitor displays information that is sent from thevideo card. The monitor is basically a television set that does nothave any tuner or audio circuits, but can display information sentdirectly from a computer. The monitor that is used with thecomputer must be the same type of monitor that the video card is

Lessoi13


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The most common monitor that is available today is the super VGAmonitor. This monitor has the ability to display 16.7 million colors ata resolution of 1280 X 1024 pixels. Repair of computer monitorsare normally limited to those individuals that are trained in therepair of televisions since extremely hazardous voltages arepresent inside the monitor.

Assignment:Answer the following multiple-choice questions:1. The video card is not used by the computer to display images onthe monitor.

a. Trueb. False2. The electron gun beams bend to create the complete image, soyou can see the image on the monitor.

a. Trueb. False3. The term "Shadow Mask" means a metal sheet with holes in the

middle to help keep the beams aligned with the phosphors.a. Trueb. False4. The beams scroll across the screen horizontally at 60 times asecond.a. True

b. False5. The term "LCD" for laptops means Liquid Crystal Display.a. Trueb. False


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The Power SupplyObjectives:When you have completed this lesson, you will:1. Understand how a power supply works.

Lesson 4

2. Understand the various connectors and their functions.3. Be able to locate and identify a common fault associated with thepower supply.


Discussion:1. The power supply is connected to the household outlet, whichsupplies 120 VAC (Volts Alternating Current) power to thecomputer. The power supply consists of:

Circuits that change the household power into the powerneeded for the computer to operate. A cooling fan to reduce the temperature inside the computer


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Lesson 4

POWERSWITCH

The Power Supply

RED -+50CVOLTSBLACK ] GROUNDBLACKYEllOW - + 1 2

L- .J I I I I I I+ q, al I + + "'0U'1 :c .... .... U'1 00 0 0 N N 0 :e:i" l i" l C i" l I"l"1< < ;z: < :c0 0 0 0r r r al.... .... -f 0Vl Vl Vl 00

2. The computer needs Direct Current or DC to operate and as suchhas the following outputs. +5, +12, -12, -5 volts DC. In addition, aspecial output called the power good signal is sent from the powersupply to the motherboard to inform the CPU and the reset controlcircuits that the power supply is working and that all the necessarysupply voltages are present.

3. When the power supply is first turned on, the power good signal isheld low, or set at 0 Volts, this prevents the motherboard fromresetting and starting the normal boot up procedures, as the powersupply voltages increase to their normal levels, the circuitry insidethe power supply monitors all of the output voltages. When allvoltages are at their correct level, the power good signal changesfrom low to high or to 5 Volts.

4. Once the power good signal is high, the reset control logic on themainboard will reset the CPU and start the normal boot procedure.The power supply also incorporates a logic circuit that will detect anoverload or a short circuit and will immediately turn off the power.The logic circuit requires that a load be connected to the powersupply at all times in order for the supply to even turn on.Therefore, it is necessary always to have something such as a disk


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The Power Supply Lesson 4

5. The power supply used in the personal computer is known as aswitching power supply, and as such is a complicated circuit.Repairs to this type of supply are limited to the diagnosis of theproblem and the replacement of the supply. Unlike all of thecomponents in the personal computer, the voltages that arecontained inside the power supply can kill you! Never attempt toopen, or in any way modify the power supply unless you are atrained electronics technician familiar with the workings of switchmode supplies.

Equipment Setup Procedures:If your computer repair trainer has not been setup, ask yourteacher for the equipment setup procedure sheet before beginningthe procedure below.

Procedure:1. Open the CD-ROM tray.2. Insert the CD-ROM "How Computers Work" into the Drive.3. Close the CD-ROM tray.4. Put on your stereo headphones.5. Use the mouse to double click on the icon "How Computers Work".6. If a warning message occurs on the screen, click on "OK".7. When the music starts and the title screen appears move the

mouse cursor anywhere on the screen and click once using the leftmouse button. This will help the user to quickly start the programby bypassing the title screen and make the music stop playing.8. You are about to go on a tour of the Power Supply.g. Move the mouse cursor to the picture of the computer case andclick once on the front of the computer.10. Then move the mouse cursor to the picture of the Power Supplyand click once.


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Lesson 4 The Power Supply

11. When the tour of the Power Supply is finished, click on "Main" togo to the main menu.12. Then move the mouse cursor to the picture of the computer case

and click once on the back of the computer.13. Then move the mouse cursor to the picture of the Power Supply(Back) and click once.

Sit back and enjoy!!!14. When the tour of the Power Supply (Back) is finished, click on"Main" to go to the main menu.15. Click on "Exit" to exit the program.16. Click on "OK" when asked "Are you sure you want to leave?"17. Click on "OK" again.You have just exited the multimedia program.Computer Repair and Fault Insertion:IFault Insertion I1. Please follow the correct procedures in turning the computer repairtrainer "OFF".COMPUTER SHUT-OFF INSTRUCTIONS:

Since the computer repair system uses Windows as its operatingsystem, it is very important to use the correct procedure whenturning off the computer.Failure to use the proper shut-off procedure may result inpermanent damage to the computer.A. Using your mouse, click once with the left mouse button onthe start box in the lower left hand corner.B. Move the mouse cursor to "Shut down" and click the leftmouse button once.


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The Power Supply

C. The computer will ask, "What do you want the computer todo?" Make sure "shutdown" is selected and click on "OK".With the "ATX" style computer, the computer will shutdown onit's own.D. With the "AT" style computer, the computer will tell you "It'snow safe to turn off your computer".E. Turn the computer OFF.

2. Ask your instructor for the key to the key switch located on the rightside of the trainer.3. Insert the key and rotate the key to a horizontal position.4. Move the fault switch on the computer repair trainer to position two.This will insert a fault in the power supply.5. Turn the power to the computer repair trainer on.


The computer did not start normally. You should notice that thecomputer is completely dead. There is no hard disk or floppy diskc;lctivity, the POST card is not displaying any information, and thereare no beeps or error codes.

Lesson 4

7. What symptoms did you observe?a. You should observe that the computer did not boot at all. The

monitor was dark, however the power on the indicator for themonitor was on. (Note: With some "green" monitors the powerindicator light may turn orange, flashing or be off although themonitor is turned on).b. You also should have noticed that the system had no power onthe indicators, the POST card was blank, however, the powerindicators (+5,+12,-12,-5) were on.c. This is a common type of misleading fault, it appears to the

casual user that the power supply is on, and working since thefan and some supplies are on.


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Lesson 4

IDIAGNOSIS IThe Power Supply

8. This is an easy diagnosis, since the computer is basically "dead".There are very few components in the personal computer that cancause a totally dead machine. The most common is a defectivepower supply.

9. Based upon these observations, there are several possible thingsthat can be wrong with the computer.a. Defective Power Supplyb. A Defective expansion card or slotc. Defective peripheral device connected directly to the powersupplyDefective Power SupplySince the power supply produces all the necessary output voltagesfor all devices installed in the computer, the power supply would bethe first and most likely suspect. Remember the power supply canbe good, but the power signal may not be set. This will cause thecomputer not to start, and will produce a "dead machine"Defective Expansion CardIf by chance. an expansion card is defective or has a defectivecomponent on it that.causes an increased demand in current. Thepower supply will immediately shut down all output voltages, andthis will result in a dead machine. To verify this type of problem,you would remove all the expansion cards, restart the computerand observe the system for signs of a normal boot. If the computerwere to start normally, you would replace each expansion cardremoved, one at a time, until the computer failed to start. Thiswould produce the defective card with the least amount of work.Defective Peripheral DeviceAs with a defective card, a defective hard disk, floppy disk, CD-ROM drive, or any device connected directly to the power supplywill cause the power supply to shut down. You would troubleshootthis problem the same way by removing all peripherals andrestarting the computer. If it starts normally, you would replaceeach component, one at a time until the offending part is found.


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The Power Supply

IREPAIR IThe repair procedure for the symptoms stated will be to replace thedefective power supply. Since the power supply is a switch modesupply and is extremely complicated to repair, and the replacementcost ofa new power supply is under $50.00, it is cost effective toreplace the power supply with a new one.Repair Procedure1. Since this fault prevented the computer from startingnormally, there is no need to follow a special shut-downprocedure.2. Turn off the main power switch.3. Turn fault switch to the original "No Fault" position and turnthe key switch original vertical position.4. Your computer is now ready to proceed with the next lesson.

Review:

Lesson 4

The power supply is used to convert household current intovoltages and currents that the personal computer utilizes. Thesupply provides 4 different output voltages and a power goodsignal to the computer. Inside the supply, hazardous voltages arepresent and no one should open the supply unless they are totallyfamiliar with the operation.

Assignment:Answer the following multiple-choice questions:1. The Power Supply is a device used to convert 120 VAC to avoltage that the computer can use.

a. True. Jb. False.

2. Should you open the power supply to see what the inside looks likeor for any other reason?a. Yes.


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The Floppy Disk DriveObjectives:When you have completed this lesson, you will:

Lesson 5

1. Understand the component parts of a floppy disk drive.2. Understand how the floppy disk drive works.3. Be able to locate and identify a common fault with the floppy disk

drive.4. Be able to locate and identify a common fault with the floppy drivecontrol system.Materials Needed:1. CES Computer Repair Trainer Model CES 975.2. CES Computer Repair Module Manual.3. Blank 3 %" disk.

H ~ ~ ~ ~ ~ : J Y B. BOTTOM VIEW

STEPPER MOTOR POWER CONNECTOR(SUPPLIES .5'1 POYER TO DRIVE) DATA CABLE(INPUTlOUTPUTCOMMANDS FROMCOMPUTER OR MULT1-1I0 CONTROLLER)

SPINDLE MOTOR(TURNS FLOPPY DISK)

DISK SLOT


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Lesson 5

Discussion:

The Floppy Disk Driv.e

1. Before the CD-ROM, the floppy disk was the primary method ofintroducing new software or programs to the computer. Originally,the floppy disk was a large 8" disk that was able to hold a largeamount of data for its time, 128K, however the modern floppy disk,3%" in size, is able to hold 1.44 Meg of information.

2. The information is stored on the floppy disk in magnetic variations,similar to the way a cassette tape stores music. The majordifference between the cassette tape and the floppy disk is that thedata stored on the floppy disk represents information as 1's or D's.The information is magnetic variations that are detected by theread/write head and is interpreted by the control logic on board thefloppy disk drive. The music stored on the cassette tape is ananalog signal that varies in frequency and amplitude.

DATA CABLE(INPUTIOUTPUTCOMMANDS FROMCOMPUTER OR MULTI-11O CONTROLL

SPINDLE MOTOR(TURNS FLOPPY DISK)

WRITE PROTECTDETECTOR TOP VIEW HI DENSITYDETECTOR BOTTOM VIEW

DRIVEACTIVEUGHT FRONT VIEW DISK RElEASE


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The Floppy Disk Drive Lesson 5

3. The basic component parts of a typical 3% floppy disk drive are:a. The Disk Drive HubThis is the mechanical mount that allows the disk to be turnedby the drive motor.b. The Drive MotorThis motor is a servo-controlled motor, which means that aspecial signal is sent to the control electronics on the disk drivethat monitors the speed at which the motor is turning.c. The Read-Write HeadThis is the most important part of the disk drive. The Read-Writehead detects and produces the small magnetic signals thatcorrespond to the information that you are reading or writing(storing) onto the surface of the disk. The read-write head isdriven forward and back by a special motor called a steppermotor.d. Write Protect SystemA light beam is projected through a small hole cut into theplastic case of the disk. If the light is not detected, informationcan be stored on the disk; this is called writing to the disk. If thelight is detected, the information cannot be written onto the disk.

DRIVE SPINDLE

WRITE PROTECT SLIDEOPEN - WRITE PROTECTEDCLOSED -WRITE ENABLED

A. DENSITY B.DETECTIONHOLE: DISK CAPACITY =1.44 MEGNO HOLE: DISK CAPACITY = 720 K

DISK PROTECTION SHUTTER,r---- READ/Y/RITEACCESS HOLE

Equipment Setup Procedures:If your computer repair trainer has not been setup, ask yourteacher for the equipment setup procedure sheet before beginning


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Lesson 5

Procedure:1. Open the CD-ROM tray.

The Floppy Disk Drive

2. Insert the CD-ROM "How Computers Work" into the Drive.3. Close the CD-ROM tray.4. Put on your stereo headphones.5. Use the mouse to double click on the icon "How Computers Work".6. When a warning message occurs on the screen, click on "OK".7. When the music starts and the title screen appears move themouse cursor anywhere on the screen and click once using the leftmouse button. This will help the user to quickly start the programby bypassing the title screen and make the music stop playing.8. You are about to go on a tour of the Floppy Disk Drive.9. Move the mouse cursor to the picture of the computer case andclick once on the front of the computer.10. Then move the mouse cursor to the picture of the Floppy DiskDrive and click once.

Sit back and enjoy!!!11. When the tour of the Floppy Disk Drive is finished click on "Main"to go to the main menu.12. Click on "Exit" to exitthe program.13. Click on "OK" when asked "Are you sure you want to leave?"14. Click on "OK" again.

You have just exited the multimedia program.


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Lesson 5

ISYMPTOMIThe Floppy Disk Drive

6. Does the computer repair trainer start normally?It should be noted that the computer did start normally, and as ofnow, appears to be functioning correctly. This fault is what is knownas a non-critical error. The computer's POST did not detect theerror, nor is the error severe enough to cause the computer to halt.

7. What symptoms did you observe?You should have observed that the computer appears normal. Youwill now learn about diagnostic troubleshooting. Since the computerappears to be functioning normally, you now must investigate whatis wrong. The topic of this lesson is the disk drive, so you can besure that the problem that you are looking for is associated with thedisk drive system. To determine the problem, you will need aformatted floppy disk, and then proceed with the following.a. Insert the disk into the floppy disk drive.b. Open up the Icon called My Computer by double clicking on theicon.c. Double click on the floppy disk drive 3% icon.d. Wait for the computer to respond.You should have received an error message generated by theoperating system that the disk in drive A is not formatted.Based upon these observations, the following may be the cause ofthis problem.a. Defective Disketteb. Defective Disk Drivec. Defective Disk Drive Controller

IDIAGNOSISIDefective DisketteThe error that you just observed may be caused by a number ofpossibilities. The most common is that the floppy disk itself isdefective or is simply not formatted. Since the operating systemcaused an error code to be displayed and attempted to format the


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be to simply try another diskette and see if the problem is stillpresent.Defective Disk DriveAfter changing the disk and trying again, unsuccessfully to formator read the disk, it is possible that the problem is associated withthe floppy disk drive itself. The problem may be dirty read-writeheads, which is common in areas of high dust, or it may be a drivethat is out of alignment. Head cleaning can be accomplished withvarious head cleaning diskettes. Alignments are generally not doneanymore. The cost of the equipment and the time to perform thealignment costs more than a new disk drive.Defective Drive ControllerAfter changing the disk and the disk drive itself, the only otherpossibility is that the disk drive controller is defective. If thecontroller is an expansion card, this can easily be replaced. If thecontroller is part of the motherboard, the replacement can either bethe changing of the motherboard, or the installation of a separatedrive controller and disabling the controller on the motherboard.The problem that you observed in this case is caused by adefective floppy drive.

IREPAIR IThe repair for this fault would be to replace the defective floppydisk drive. The cost of repairing the drive would far exceed the costof a new disk drive.

Repair Procedure:1. Since this fault did not prevent the computer from starting normally,you must follow the special shut-down procedure.2. Click on "no" to answer the question do you want to format the disknow?3. Click on the "x" in the upper right corner of the screen to close the"My computer" window.COMPUTER SHUT-OFF INSTRUCTIONS:

Lesson 5


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Lesson 5 The Floppy Disk Drive

Failure to use the proper shut-off procedure may result inpermanent damage to the computer.A. Using your mouse, click once with the left mouse button on

the start box in the lower left hand corner.D. Move the mouse cursor to "Shut down" and click the leftmouse button once.E. The computer will ask, "What do you want the computer todo?" Make sure "shutdown" is selected and click on "OK".With the "ATX" style computer, the computer will shutdown onit's own.D. With the "AT" style computer, the computer will tell you "It'snow safe to turn off your computer".E. Turn the computer "OFF".

4. Turn fault switch to the original "No Fault" position.5. Your computer is now ready to proceed.REVIEW:

Normally a problem associated with a floppy disk drive canoriginate from a number of causes, most of which are due to a baddisk or a improperly formatted disk. Since the disk drive was "bad",there are a few reasons that the drive itself may be unable to readthe disk. The drive itself may be out of alignment, have defectiveread-write heads, have a defective controller or may just be dirty.The floppy disk drive is considered a disposable part, after you trythe obvious, such as changing disks, and cleaning the drive, youwould replace the disk drive.

INSERTING ANOTHER FAULT1. Move fault switch to position four.This will insert a fault in the floppy disk drive system.2. Turn the power to the computer repair trainer on.


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The Hoppy Disk Drive


It should be noted that the computer did not start normally. ThePOST diagnostic program detected a fatal or critical error andhalted the computer.

Lesson 5

4. What symptoms did you observe?You should have observed that the computer did not start normally,and that the computer's internal diagnostic ROM program detectedthat there is a problem with the floppy disk drive system.An error message is displayed on the monitor stating the followingmessage Floppy disk(s) fail (40). In addition to the messagedisplayed on the monitor screen the POST Diagnostic Card is alsodisplaying a code other than the normal code for this computer.Based upon your observations, there are a number of possiblethings that can be wrong with the computer.a. The disk drive is defective.b. The disk drive cable is bad.c. The drive controller is defective.d. The motherboard is bad.Defective Disk DriveUnlike the previous error, this problem caused a critical or fatalerror to be generated. In order for this type of an error to occur, theproblem must be detected by the POST. The post only tests for thepresence of the floppy disk drive and the type of disk driveinstalled. The test also issues a reset drive status request, whichcauses the drive to look for the track 0 position. If any of the testsfail to complete, or generate any errors during the POST an errorwill result.Defective Drive CableThis could cause an error to be produced; however, defectivecables do not normally happen by themselves. The most common"Defective Cable" is when the cable is partially connected to thedevice or motherboard. Always check the connectors at both endsof the device for proper connections.


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Defective Drive ControllerA defective drive controller will usually cause a failure and a criticalerror to be displayed. If the drive controller in the computer that youare repairing is a separate card, try swapping the suspected badcard with a good one, and retesting the computer. If it is part of themotherboard, you may have to change the motherboard or install aseparate controller and disable the controller installed on themotherboardDefective MotherboardIt is possible for the problem to be associated with a defectivemotherboard, specifically the DMA or Direct Memory Accesschannel that controls the transfer of information from the floppy diskto the memory. While this is a rare problem, it can and doeshappen. If after changing all the recommended components first,the motherboard would be the last resort.

IREPAIR IThe fault that is inserted in this computer is related to the diskcontroller circuits. The disk controller interprets all operating systemcommands and instructs the disk drive accordingly. Since thiscomputer has all of the peripheral controllers located on themotherboard, there are only two choices in order to repair thiscomputer. The first is to disable the onboard controller and installan external controller in one of the expansion slots, this is the mostcost effective method of repair. The second, more expensivemethod would be to replace the motherboard.Repair Procedure:1. Since this fault prevented the computer from starting normally,there is no need to follow a special shut-down procedure.2. Turn off the main power switch.3. Turn fault switch to the original "No Fault" position and turnthe key switch to the original vertical position.4. Your computer is now ready to proceed with the next lesson.

Review:


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computer. The type of floppy disk used will determine the storagecapacity of the disk, with 3 high-density disks holding about 1.4megabytes of data. A new type of floppy disk has been developedthat stores 120 megabytes on the same type of 3 disk, however,with the popularity of recordable compact discs holding 650700MB, they never became popular.

Assignment:Answer the following multiple-choice questions:1. Floppy disks are used to:a. Carry new programs.b. Save data.c. Move files from one PC to another.d. All of the above.2. If the write protect tab is in the open position:a. A light passes through the hole in the disk and tells thecomputer it is okay to write data to the disk.

b. Light passes through the hole and tells the PC not to write datato the disk.c. It has no effect because floppy disks cannot be write protected.d. None of the above.3. Zero's and One's are the binary language of the computer.

a. Trueb. False4. The most common type of floppy drive used in computers today is:a. 3.5" Disk Driveb. 5.25" Disk Drivec. Tape Drived. 8" Disk Drive5. The "cookie" is:a. The working disk inside the jacket of the floppy disk.b. Coated with a thin layer of magnetic material.

c. Spun inside the jacket by a motor on the disk drive.d. All of the above.

Lesson 5


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6. The Tape Drive is another device used to store and transport datato another machine.a. Trueb. False

7. The thin inner disk in a 3.5" disk is called a "cookie".a. Trueb. False

8. To read the data from a disk, the read/write heads move onto thesurface of the cookie.a. Trueb. False

9. 3.5" floppy disks can store:a. More data than a 5.25" floppy.b. Less data than a 5.25" floppy.c. The same amount of data as a 5.25" floppy.d. None of the above.

10. The read/write head is used to transfer information to and from thefloppy disk.a. Trueb. False


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The Hard Disk DriveObjectives:When you have completed this lesson, you will:

lesson 6

1. Understand the component parts of a hard disk drive.2. Understandhow the hard disk drive works.3. Be ablerto locc;lte and identify a common fault in the hard disk drive.


PO .....ERCONNECTORDISKPLATTER

DRIVE.SPINDLER/WHEADS

HEADPOSITIONER"VOICE COIL"DRIVER[NOVES HEADS)

1/0INTERFACE

Discussion:TOP VIEW BOTTONVIE"'"

1. The information is stored on the hard disk in magnetic variations;similar to the way the information is stored onto a floppy disk. The


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Lesson 6 The Hard Disk Drive

The information stored on the hard drive is a much larger quantityof data due to the fact that the hard drive hasmore recordingarea.This is because it has more than one recording surface, hasmultiple read and write heads, and has a higher recording densitythen that of a floppy drive.

HEADPOSITIONER"VOICE COIL"DRIVER(MOVES HEADS)

TOPVIEW

POWERCONNECTORDISKPLATTER

DRIVESPINDLE.r - - t l 1 - R/WHEADS

1/0.. INTERFACE

BOTTOM VIEW

2. Unlike the floppy disk when first taken out of the box, the hard drivecomes from the factory completely formatted. This format is calledthe low level format, and like the floppy, the low level formatactually defines the tracks and sectors of the disk surface. Beforethe hard disk is useable to the computer, additional formattinginformation is required.The process of low .level formatting cannot be done in the field.Special software and in some cases special hardware is required tolow level format a drive. It is possible to damage a hard diskbeyond repair by low level formatting the disk. Be sure wheneveryou think of low level formatting a disk, the drive supports thecommand and the software you are using is correct for the drivetype.

3. The hard disk utility from DOS called FDISK is part of theformatting procedure to make the computer able to recognize thehard disk. The FDISK utility will define the media type, and themaster boot record. Once this information has been added to the


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The Hard Disk Drive Lesson 6

4. High Level Formatting erases all the information that is stored onthe hard disk, however, it is a necessary step in the installation of ahard drive. Note that this utility does not actually format the disk asit does in formatting a floppy, but simply verifies that the disksurface is good. Once the disk has been verified, the Boot Sector,FAT (File Allocation Table) and Directory Structure is created, andthe disk is then ready for use.

5. The mechanical operation of the hard disk is similar to that of thefloppy disk, with one major exception. The read and write headsnever touch the surface of the revolving disk. The heads fly on acushion of air, and actually float over the surface of the disk. Thespace between the disk and the read-write heads are smaller thanthe size of a human hair.The read-write heads detect the magnetic changes in the sameway as the floppy disk, but never actually touch the disk. The termhard drive crash, although sometimes refers to the fact that thedrive itself is not working, means the read-write head actuallytouched the surface of the disk. This action will destroy both theread-write head and the disk surface.

HEADPOSITIONER"VOICE COIL"DRIVER(MOVES HEADS)

TOP VIEW

DISKPLATTER

DRIVESPINDLER/WHEADS

1/0INTERFACE

POWERDATA C O N N E C T O R ~INTERFACE '%

DRIVESELECTJUMPERS

BOTTOM VIEW6. The hard drive is sensitive to shock, simply bumping a runningdrive can damage the disk. Caution should always be exercised


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7. The interface to the hard drive consists of a data signal, whichcontains all the command and data information. This data istransferred on a ribbon cable that has between 34 and 50conductors, depending upon the drive type. Most PersonalComputers utilize the IDE or Integrated Drive Electronics Interfaceand use a 34-pin connector. Power supply requirements are +5 and+12 Volts for most hard drives.

Equipment Setup Procedures:If your computer repair trainer has not been setup, ask yourteacher for the equipment setup procedure sheet before beginningthe procedure below.

Procedure:1. Open the CD-ROM tray.2. Insert the CD-ROM "How Computers Work" into the drive.3. Close the CD-ROM tray.4. Put on your stereo headphones.5. Use the mouse to double click on the icon "How Computers Work".6. If awarning message occurs on the screen, click on "OK".7. When the music starts and the title screen appears move themouse cursor anywhere on the screen and click once using the leftmouse button. This will help the user to quickly start the programby bypassing the title screen and make the music stop playing.8. You are about to go on a tour of the Hard Disk Drive.9. Move the mouse cursor to the picture of the computer case andclick once on the front of the computer.10. Then move the mouse cursor to the picture of the Hard Disk Driveand click once.


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The Hard Disk Drive

11. When the tour of the Hard Disk Drive is finished click on "Main" togo to the main menu.12. Click on "Exit" to exit the program.13. Click on "OK" when asked "Are you sure you want to leave?"14. Click on "OK" again.You have just exited the multimedia program.Computer Repair and Fault Insertion:

Lesson 6

IFault InsertionI1. Please follow the correct procedures in turning the computer repairtrainer "OFF".COMPUTER SHUT-OFF INSTRUCTIONS:

Since the computer repair system uses Windows as its operatingsystem, it is very important to use the correct procedure whenturning off the computer.Failure to LIse the proper shut-off procedure may result inpermanent damage to the computer.A. Using your mouse, click once with the left mouse button onthe start box in the lower left hand corner.B. Move the mouse cursor to "Shut down" and click the leftmouse button once.C. The computer will ask, "What do you want the computer todo?" Make sure "shutdown" is selected and click on "OK".With the "ATX" style computer, the computer will shutdown on

it's own.D. With the "AT" style computer, the computer will tell you "It'snow safe to turn off your computer".E. Turn the computer "OFF".

2. Ask your instructor for the key to the key switch located on the right


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3. Insertthe key and rotate the key to a horizontal position.4. Move fault switch to position five.This will insert a fault in the hard disk drive system.5. Turn the power to the computer repair trainer on.ISYMPTOM I6. Does the computer repair trainer start normally?

It should not start normally because of the fault in the hard drive.7. What symptoms did you observe?You should have observed that Windows 98 did not start normally.The computer did not even boot. The computer displayed a"Primary master hard disk fail" message.8. Based

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Computer Repair I