Table Of Content• Shadab Saifi (Illustrator) • Ayaz Uddin (Editor)
Vayu Education of India
2/25, Ansari Road, Darya Ganj, New Delhi-110 002
1.Repair, Servicing and Maintenance Concepts............................................................................1
1.1. Introduction of Servicing and Maintenance............................................................................................1
1.1.1 Preventive Maintenance............................................................................................................2
1.1.2 Corrective Maintenance ............................................................................................................3
1.1.3 Maintenance Activities..............................................................................................................2
1.1.4 The Indenture level....................................................................................................................4
1.1.5 The Maintenance Level.............................................................................................................4
1.1.6 The Maintenance Line or Echelon.............................................................................................5
1.1.7 The Maintenance Policy............................................................................................................6
1.2 Meantime Between Failure (MTBF), Meantime To Repair (MTTR) Maintenance Policy.........................7
1.2.1 Introduction...............................................................................................................................7
1.2.2 What is a Failure? What are the Assumptions?.........................................................................7
1.2.3 Reliability, Availability, MTBF, and MTTR Defined...................................................................8
1.2.4 Methods of Predicting and Estimating MTBF.........................................................................11
1.2.4.1 Reliability Prediction Methods.......................................................................................11
1.2.4.2 Reliability Estimation Methods.......................................................................................13
1.2.5 Conclusions.............................................................................................................................14
1.3 Potential Problems of Preventive Maintenance and Corrective Maintenance.......................................14
1.3.1. Relationship to Preventive Maintenance to Corrective Maintenance......................................16
1.4. Circuit Tracing techniques.....................................................................................................................18
1.5. Concept of Shielding, Grounding and Power Supply requirements.......................................................29
1.5.1. Power Grounding Basics..........................................................................................................29
1.5.2 Grounding, Bonding and Overload Protection........................................................................30
1.5.2.1. Grounding Electrode Resistance.....................................................................................31
1.5.2.2. Power Grounding Definitions.........................................................................................31
1.5.2.3. Separately derived Instrumentation Power System.........................................................32
1.5.2.4. Single-Point Grounding of Power Supplies.....................................................................33
1.5.2.5. The Ungrounded System................................................................................................34
1.5.2.6. Resistance Grounding....................................................................................................35
1.5.2.7. Shielding Theory............................................................................................................35
1.5.2.8. Power Supply Shielding................................................................................................40
1.6. Considerations of Computers and its Peripherals..................................................................................42
Exercise..................................................................................................................................................43
2.Fundamental Troubleshooting Procedures ...............................................................................44
2.1 Troubleshooting Process.......................................................................................................................44
2.1.1 Fault Establishment.................................................................................................................44
2.2 Fault Location.......................................................................................................................................44
(Vii)
2.2.1 Fault Correction.......................................................................................................................44
2.2.2 Fault Location Procedure.........................................................................................................44
2.3 Fault Finding Aids................................................................................................................................46
2.4 Service Manuals...................................................................................................................................46
2.5 Testing and Measuring Instruments.....................................................................................................47
2.6 Special Tools.........................................................................................................................................47
Excercise................................................................................................................................................50
3. Hardware and Software Faults..................................................................................................51
3.1. Troubleshooting Techniques.................................................................................................... 51
3.1.1 Preliminary Observations.........................................................................................................51
3.2 Different Troubleshooting Techniques and Methods ...........................................................................53
3.3 Functional Area Approach....................................................................................................................53
3.4 Split-Half Method.................................................................................................................................53
3.5 Divergent, Convergent and Feedback path circuits...............................................................................54
3.5.1 Divergent Paths.......................................................................................................................54
3.5.2. Convergent Paths....................................................................................................................55
3.5.2. Feedback Paths........................................................................................................................55
3.5.2.1. Switching Paths..............................................................................................................56
3.6 Analysis Measured techniques.............................................................................................................56
3.6.1 Software Test Techniques for System Fault-Tree Analysis.....................................................61
Exercise..................................................................................................................................................65
4. Troubleshooting of Computers: Components and Peripherals ..........................................66
4.1 Motherboard..........................................................................................................................................66
4.1.1 Troubleshooting of Mother Board..........................................................................................67
4.2 Floppy Disk Drive (FDD).......................................................................................................................71
4.2.1 Trouble shooting of FDD........................................................................................................73
4.2.1.1 Bad Floppy Diskette.......................................................................................................73
4.2.1.2 Not Setup in CMOS........................................................................................................74
4.2.1.3 Confliction with other hardware......................................................................................74
4.2.1.4 Not Connected Properly.................................................................................................74
4.2.1.5 Bad Drivers.....................................................................................................................75
4.2.1.6 Bad Hardware.................................................................................................................75
4.3 Hard Disk Drive (HDD)..........................................................................................................................75
4.3.1 Form Factors...........................................................................................................................76
4.3.2 Troubleshooting of Hard Drive...............................................................................................77
4.3.2.1 Checking Physical connectivity.....................................................................................77
4.3.2.2 Checking Jumper Settings...............................................................................................78
4.3.2.3 Checking SCSI Termination ............................................................................................78
4.3.2.4 Checking BIOS Setup (IDE only)...................................................................................79
4.3.2.5 Virus Checking...............................................................................................................79
4.3.2.6 Checking for a Valid Partition.........................................................................................79
4.3.2.7 Checking Drive Formatting............................................................................................80
4.3.2.8 Fixing Physical and Logical Drive Errors........................................................................80
4.3.2.9 Checking and Reactivating Disks in the Windows 2k/XP Oss........................................81
4.4 CD ROM/ DVD......................................................................................................................................81
4.4.1 Troubleshooting of CD ROM/DVD.........................................................................................82
4.5 Printers...................................................................................................................................................85
4.5.1. Troubleshooting of Printers ....................................................................................................86
(Viii)
4.6 Modems................................................................................................................................................86
4.7. Monitors................................................................................................................................................89
4.7.1 Troubleshooting of Monitors..................................................................................................90
4.7.1.1 Monitor is Blank after Restarting System.......................................................................90
4.7.1.2 After Connecting a Monitor, the Picture Looks Bad......................................................90
4.7.1.3 The Monitor has Started Making a Strange Noise..........................................................90
4.7.1.4 Monitors Display Settings are not Correct....................................................................91
4.7.1.5 Display is Rotated..........................................................................................................91
4.8. Switched – mode power supply (SMPs)................................................................................................91
4.7.1 Troubleshooting of Monitors..................................................................................................90
4.8.1 SMPS and Linear Power Supply Comparison..........................................................................92
4.8.2 Theory of Operation................................................................................................................94
4.8.2.1 Input Rectifier Stage.......................................................................................................94
4.8.2.2 Inverter Stage.................................................................................................................95
4.8.2.3 Voltage Converter and Output Rectifier..........................................................................95
4.8.2.4 Regulation......................................................................................................................96
4.8.2.5 Transformer Design........................................................................................................96
4.8.2.6 Power Factor...................................................................................................................96
4.8.3 Troubleshooting of SMPs.......................................................................................................97
Excercise..............................................................................................................................................102
5. Computer Repair and Maintenance......................................................................................103
5.1 Specification, Maintenance and Repair of CVT (Constant Voltage Transformer).................................103
5.1.1 History of CVT ......................................................................................................................105
5.1.2 Uses of CVT..........................................................................................................................105
5.1.3 Operation of CVT...................................................................................................................105
5.1.4 Advantages and disadvantages............................................................................................106
5.1.5 Instructions for Use (Installation)..........................................................................................107
5.1.6 Features.................................................................................................................................107
5.1.7 Output Voltage vs. Input Voltage...........................................................................................108
5.1.8 Typical Service, Storage, and Shipment Conditions ..............................................................109
5.1.9 Application Considerations-Output Performance under Dynamic Supply Conditions..........110
5.1.9.1 Performance: Voltage Interruption.................................................................................110
5.1.9.2 Performance: Voltage Sag..............................................................................................111
5.1.9.3 Performance: Voltage Phase Shift..................................................................................111
5.1.9.4 Performance: Oscillating Transient...............................................................................111
5.1.9.5 Performance: Oscillating Transient...............................................................................112
5.1.10 Application Considerations—CVT Electrical Characteristics during Linear and Nonlinear
Loading ........................................................................................................................112
5.1.10.1 Performance: Line Current Distortion............................................................................112
5.1.10.2 Performance: Power Factor...........................................................................................113
5.1.11 Specifications: Below there is a chart of general specifications:...................................114
5.1.12 Maintenance and Repair of CVT...................................................................................115
5.2 Specification, Maintenance and Repair of UPS (Uninterruptible Power Supply)..................................115
5.2.1 Common Power Problems......................................................................................................115
5.2.2 Applications..........................................................................................................................116
5.2.2.1 N+1...............................................................................................................................116
5.2.2.2 Multiple Redundancy...................................................................................................116
5.2.2.3 Outdoor Use.................................................................................................................116
(ix)
5.2.2.3 Internal Systems...........................................................................................................116
5.3 Technologies.......................................................................................................................................116
5.3.1 Offline/Standby.....................................................................................................................117
5.3.2 Line-interactive......................................................................................................................117
5.3.3 Double-conversion/online.....................................................................................................118
5.3.4 Ferro-resonant.......................................................................................................................119
5.3.5 DC Power...............................................................................................................................119
5.3.6 Rotary....................................................................................................................................119
Exercise................................................................................................................................................120
6. Environmental Requirement of Computer System and Peripherals................................121
6.1 Environmental Requirements of Computer Systems and its Peripherals..............................................121
6.1.1 Operating Specifications........................................................................................................124
6.1.2 Temperature...........................................................................................................................124
6.1.3 Humidity................................................................................................................................125
6.1.4 Troubleshooting Environmental Conditions .........................................................................125
6.1.5 Cooling and Aisle Airflow......................................................................................................127
6.1.6 Acclimatization......................................................................................................................128
6.1.7 Vibration and Shock...............................................................................................................128
6.1.8 Contaminants.........................................................................................................................128
6.1.9 Fire Containment...................................................................................................................129
Exercise................................................................................................................................................130
7. Site Preparations and Designs ...............................................................................................131
7.1 Site Preparations and Design of Computer Rooms...............................................................................131
7.1.1 Site Selection.........................................................................................................................131
7.1.2 Fitting Out Requirements.......................................................................................................132
7.1.3 Equipment Layout Planning ..................................................................................................134
7.1.4 Electrical Requirements..........................................................................................................135
7.1.5 Air-conditioning System........................................................................................................137
7.1.6 Fire Prevention, Detection and Suppression .........................................................................138
7.1.7 Prevention of Water Leakage.................................................................................................140
7.1.8 Physical Security...................................................................................................................140
7.2 Testing Specifications and Installation of Computer Systems and Peripherals....................................141
7.2.1 Validation Overview...............................................................................................................141
7.2.2 Validation Master Plan and Project Plan................................................................................144
7.2.3 Design Qualification and Specifications................................................................................145
7.2.4 Vendor Assessment...............................................................................................................147
7.2.5 Installation Qualification........................................................................................................149
7.2.6 Operational Qualification.......................................................................................................150
7.2.7 Performance Qualification......................................................................................................151
7.2.8 Configuration Management and Control...............................................................................152
7.2.9 Validation report and Other Documents.................................................................................153
Exercise................................................................................................................................................153
Multiple Choice Questions & Answers................................................................................................154
Glossary...............................................................................................................................................160
Index....................................................................................................................................................175
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