UNIT 5 TROUBLESHOOTING PART A

Transcription

1 UNIT 5 TROUBLESHOOTING PART A 1) What are all the factors that a successful troubleshooting depends on? Successful troubleshooting depends on the following factors: 1. Problem solving approach 2. Techniques adopted in troubleshooting 3. Tools and test equipment used 4. Diagnostic aids in the PC 2) What are the types of computer faults vased on the frequency of occurences of the problem? Computer faults can be broadly classified into two types based on the occurences of the problem. 1. Permanent or solid fault 2. Intermittent fault. 3) What is Solid fault and intermittent fault? Solid fault: When there is a permanent fault in a computer, the computer behaves consistently. Any number of times the program is run, the result or symptoms will be the same. Intermittent fault: When there is an intermittent fault in a computer, the computer s behavior is not consistent. Sometimes it works properly and suddenly it malfunctions. After a certain period of time, it recovers from the fault automatically again atarts functioning properly. 4) List down the hardware problems. 1. Electronic problems 2. Mechanical problems 3. Environmental problems 4. Media problems 5) What are the types of troubleshooting tools? There are two types of troubleshooting tools: 1. Nodal tester 2. System tester 6) What are the things that a nodal tester includes? The nodal tester includes: 1. Logic probe 2. Logic pulser 3. Current tracer S.KIRUTHIGA AP/CSE,CCET Page 1

2 4. Oscilloscope 5. System testers 7) List down the possible faults in a bus. The possible faults in the bus are: 1. Two are more bits shorted 2. A bit shorted to a HIGH state Vcc or logic 1 3. A bit shorted to a LOW state ground or logic 0 4. A bit path is open due to a PCB track cut or defective PTH 5. Wrong connection 8) What is meant by dead system and list down some symptoms of a dead system? A computer is said to be dead when an absolutely essential signal is absent. Following are some of the symptoms of a dead computer: 1. The dc voltage is absent 2. The CLK signal is absent 3. System s built-in firmware is corrupted 4. ROM output is inactive 5. Microprocessor is faulty or dead 6. The ac fuse is blown 9) What is meant by spurious problem? Sometimes the computer malfunctions randomly. Logical and systematic troubleshooting may not yield any clue. In such cases the engineer should look for symptoms of spurious problems. Some of the hidden symptoms of spurious problems are listed below: 1. The dc voltage has excessive ripples. 2. The dc voltage is noisy. 3. The CLK signal is not stable. 4. There is noise pick up on the reset input or on other bus signals. 5. Momentary black out happens with an IC which is silently dying and fighting for survival. 6. Loose contacts of cables and connectors. 10) What are the reasons responsible for the occurrences of multiple faults? Some of the reasons responsible for the occurrences of multiple faults are: 1. Voltage Spikes 2. Short Circiut 3. Defective Power Supply 4. Wrong Operation S.KIRUTHIGA AP/CSE,CCET Page 2

3 11) Define Systematic troubleshooting. Systematic troubleshooting is the most powerful tool in the hands of an engineer. It is a scientific and analytical process. The systematic troubleshooting approach can be divided into the following steps: 1. Symptoms observation 2. Symptoms analysis 3. Fault diagnosis 4. Fault rectification 12) What are all the multi-dimensional view to be applied by the hardware engineer while troubleshooting problems? The many dimensions are the following: 1. Architecture 2. Organization 3. Engineering Layout 4. Environment 13) List down the layout documents related to a computer. The layout documents related to a computer are: 1. Circuit diagram 2. Board layout diagram 3. Cable signals list 4. Connectors signals list 5. Jumper settings 14) List down the problems caused due to environmental conditions. The problems that are caused due to environmental conditions are: 1. High temperature 2. Dust 3. Supply voltage fluctuations 4. Electrical interference 5. Magnetic fields 6. Humidity S.KIRUTHIGA AP/CSE,CCET Page 3

4 15) Write down the steps involved in performing one or more actions depending on the results of fault diagnosis? 1. Replacing a defective IC or other components 2. Replacing a defective PCB 3. Cleaning the connectors 4. Removing a short 5. Changing the diskette 6. Replacing a key switch 7. Isolating electrical loads 16) List down the levels of troubleshooting approaches to problems in PCs. Basically there are four levels of troubleshooting approaches to problems in PCs. They are: 1. POST behavior analysis 2. Running diagnostics 3. Probing with tools 4. Using emulator or ATE(Automated test Equipment) 17) What are the different modes used by POST? The different modes used by POST are: 1. Hang or halt at specific stages 2. Checkpoint Output on Port 80 (PPI- port A in 8088-PC) 3. Speaker tones 4. Error code display on CRT monitor 5. Detailed message on CRT monitor 18) List down the problem associated with floppy disk drive. 1. Spurious Drive Problem 2. Electromechanical problems 3. Compatibility Problem 19) List down the problems associated with Hard disk drive. The problems associated with HDD are classified into three types: 1. Mechanical failures 2. Electronic failures 3. Data failures S.KIRUTHIGA AP/CSE,CCET Page 4

5 20) What are the mechanical failures of a hard disk? The mechanical failures of a hard disk can be of the following types: 1. Worn out ball bearings in the spindle to the motor 2. Torn or broken belt connecting the spindle to the motor 3. Winding burned-out motor 4. Head crash due to dust 5. Head crash due to physical shock during handling or transportation. 21) What are the types of faults that cause data failure? Three types of fault cause data failures. 1. Bad spot on the platter 2. Dust and contamination on the platter surface 3. Dust on the read/write head 22) What are the test points in PCB that are provided by the manufacturer in order to simplify the troubleshooting of the HDD? The common test points are: 1. Differential Read Filter 2. Read Data 3. Track 0 Sensor 4. Index Sensor 23) List down typical CD-ROM drive problems and probable causes. 1. Drive door does not open 2. Drive vote recognized 3. LED glows always 24) How a Voltage spike causes system failure? A high voltage spike which enters inside, without affecting the fuse, can damage components in the SMPS, CRT monitor and even ICs in the system. 25) Define a logic probe. Logic probe is a hand held low cost test equipment with which 90% of the faults can be diagnosed without an oscilloscope which is 10 to 20 times costlier. It is used to find out the logic state of any node in a circuit including steady states and pulses. S.KIRUTHIGA AP/CSE,CCET Page 5

6 PART - B 1. Explain computer fault, Nature of the fault and fault types. Types of symptoms Nature of faults: Permanent fault Intermittent fault Types of faults: Electronic Problems Mechanical Problems Environmental Problems Media Problems 2. Explain Diagnostic programs and tools. Explain Diagnostic program Trouble shooting tools: Nodal tester: Logic Probe Logic Pulser Current Tracer Oscilloscope System tester 3. Explain Fault elimination process. Common fault elimination steps Dead system Spurious problems Security failures Heart beats: Keyboard Flash Memory Refresh Request Timer 0-Ticks Multiple Faults: Voltage Spikes Short Circuit Defective Power Supply Wrong Operation S.KIRUTHIGA AP/CSE,CCET Page 6

7 4. Explain Systematic Troubleshooting and Troubleshooting levels. Symptoms observation Symptoms analysis Fault diagnosis: Architecture Organisation Engineering layout Environment Fault rectification Troubleshooting levels: POST behavior analysis Running diagnostics Probing with tools Using emulator or ATE 5. Explain Floppy disk drive and CD-ROM problems. Floppy Disk Drive Problems: Spurious Drive Problem Electrmechanical Problems Compatibility Problems CD-ROM problems: Fault Symptoms Trouble sources Suggested actions 6. Explain Hard disk Drive Problems. Mechanical Failures Electronic Failures Data Failures: Wake UP Diagnostics Controller Diagnostics S.KIRUTHIGA AP/CSE,CCET Page 7