Maintaining Electronic Systems - Rilegato

Whitaker, Jerry C.

Rilegato

ISBN 10: 0849374111 ISBN 13: 9780849374111

Casa editrice: CRC Press, 1991

Riassunto

During the past decade, electronic products have undergone immense changes. Most hardware contains tens or hundreds of integrated circuits, many of them surface-mounted devices. Those responsible for maintaining this equipment, however, are struggling to keep up with manufacturers of the gear. Technology has altered the way electronic products are designed and constructed. The service bench needs to change as well. Maintaining Electronic Systems examines the maintenance of electronic systems for critical-use applications and is directed toward technician-level engineering personnel involved in the installation and maintenance of electronic equipment for industry. The book examines electronic systems used today in a wide variety of applications and explains how to identify and correct hardware failures. The tools necessary for this work are also identified and their operation discussed.

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Contenuti

THE MECHANICS OF COMPONENT FAILURE: AN ANALYSIS OF WHY PARTS FAIL, AND THE PROBABLE LIFETIME OF VARIOUS TYPES OF DEVICES USED IN INDUSTRIAL ELECTRONIC SYSTEMS. RELIABILITY THEORY. Statistical Reliability Studies. The Bathtub Curve. Infant Mortality Syndrome. The Benefits of Product Burn-In. Environmental Stress Screening. Power Cycling. Temperature Cycling. Vibration. Field Experience. Components Likely to Fail. Typical Failure Modes. Effects of Component Failure. SEMICONDUCTOR FAILURE MODES. Failure Mechanisms. Mechanical. Electrical. Effects of Various Failure Modes. Stress-Induced Failures. Discrete Transistor Failures. Avalanche Breakdown. Alpha Multiplication. Punch-Through. Thermal Runaway. Heat Removal From a Semiconductor. Thermal Transfer Properties. Thermal Resistance. Heat Sink Interface. ESD Failures. Damage Potential Threshold. VACUUM TUBE FAILURE MODES. Decarburization Rate. Effects of Vacuum Processing. Filament Voltage Management. External Failure Modes. Excessive Dissipation. Socketing Problems. External Arcing. Internal Arcing. PASSIVE COMPONENT FAILURE MODES. Capacitors. Electrolytic Devices. Dielectric Absorption. Change in Value. Short-Circuit Mode. Life Expectancy. Transformers. Core Temperature. Winding Insulation Breakdown. Resistors. Fixed Resistors. Variable Resistors. Fault Protection Devices. Fuses. Circuit Breakers. THE WORK BENCH: THE TEST EQUIPMENT AND TOOLS NEEDED TO SERVICE CURRENT-TECHNOLOGY ELECTRONIC SYSTEMS. SERVICE REQUIREMENTS TODAY. Test Equipment. Digital/Analog Oscilloscopes. Basic Test Gear. Audio Test Equipment. Video Test Equipment. RF Test Gear. Tools for Servicing Electronic Products. Tool Kits. Test Jigs and Fixtures. Testing Adaptors. Checklist. SOLDERING EQUIPMENT. PWB Rework Requirements. Heat Limitations. Desoldering Methods. Electrostatic Discharge Considerations. Using Solder Flux. Rework with Surface-and Chip-Mount Devices. Tools for the Job. Possibility of Device Damage. Checking for Solder Bridges. USING CHEMICALS IN THE SHOP. Types Available. Chlorofluorocarbons. Chlorinated Solvents. Alcohols. Chemical Blends. Application Methods. Cotton Products. Presaturated Products. Compressed Gas Products. Contact Cleaners/Lubricants. Application Considerations. PREVENTING ESD FAILURES. Potential for Damage. Training Personnel. Static-Control Products. Wrist Straps. Grounding Mats. Shipping Products. Safety Considerations. FINDING REPLACEMENT PARTS. Using General-Purpose Replacements. Pin Differences. Stud-Mounted Devices. TOOLS FOR SERVICING COMPUTER-BASED HARDWARE: A REVIEW OF THE TEST INSTRUMENTS AVAILABLE TO CHECK LOGIC SYSTEMS AND COMPUTER-BASED HARDWARE. BASIC LOGIC TEST INSTRUMENTS. Digital Multimeter. Voltage/Current Ranges. Autoranging Features. Audible Outputs. Test Probes. Logic Probes. Types Available. Features. Pulser Features. Logic Current Tracer. Break-Out Boxes. Types Available. Capabilities. Test Applications. SIGNATURE ANALYZERS. Capabilities. Bit Stream Translation. Data Interpretation. Data Readout. Comparing Results Against Known Data. Stock Data Reports. Archive Reports. Operational Considerations. Clock Rates. Microprocessor Interface. Searching for Stable Data. GUIDED-PROBE DIAGNOSTIC SYSTEMS. Applicable Systems. High Volume Products. High Dollar Products. Capabilities. Test Library. Building a Test Library. Limits of ATE Systems. Guided Probe-vs.-Manual Probe. Cost Justification. Volume Required for ATE Systems. Reduction in Service Time Required. PC-Based Diagnostic Systems. Applications. Capabilities. DISK DRIVE ANALYZERS. Software Test Systems. Test Capabilities. Isolating a Faulty Device. Hardware Test Systems. Read Margin Measurements. Analog Device Analysis. Digital Device Analysis. TROUBLESHOOTING DIGITAL SYSTEMS: REPAIR OF MICROPROCESSOR-BASED HARDWARE REQUIRES A DIFFERENT APPROACH TO MAINTENANCE. TROUBLESHOOTING DECISIONS. Repair to Board Level. Isolating the Faulty PWB. Spare Board Requirements. Cost Considerations. Mean-Time-to-Repair. Repair to Component Level. Isolating the Defective Component. Soldered IC Boards-vs.-Plug-in IC Boards. Spare Parts Requirements. MTTR Considerations. Service in-House or Outside. Documentation Available. Staff Experience. Cost to End-User. ISOLATING THE DEFECTIVE SUB-ASSEMBLY. Built in Diagnostic Routines. Document Working System Before It Fails. ROM-Based Test Routines. Software-Based Test Routines. Examining Error Flags. Status Register Dump. System/CPU Board. Systems that will Not Boot. Systems that Will Boot. Checking the Microprocessor Clock. Interrupt System. Master System Reset. Identifying Bus Problems. RAM Parity Errors. Solving Intermittent Problems. Peripheral Interface Problems. Parallel Ports. Serial Ports. Display Ports. Keyboard/Status Ports. Memory Problems. Floppy Disk Errors. Hard Disk Errors. Software/Hardware Fixes. Power Supply Problems. Bench-Testing the Supply. Power Control/Shutdown Circuits. Primary/Secondary Switching Circuits. Measuring Performance Against Specs. COMMUNICATIONS NETWORKS. RS-232 Communications. Data Transmission Format. Identifying Defective Part of Path. Effects of Noise on Communications. Local Area Networks. Types Commonly in Use. Physical Layer. Data-Link Layer. Network Layer. Transport Layer. Session Layer. Presentation Layer. Application Layer. Problems Experienced with LAN Systems. Identifying Defective Part of Path. Effects of Noise on Communications. RF SYSTEM MAINTENANCE: WORK THAT SHOULD BE DONE TO KEEP TRANSMISSION EQUIPMENT WORKING PROPERLY. THE IMPORTANCE OF REGULAR MAINTENANCE. Improve System Reliability. Maintain Overall Performance. Routine Maintenance. Documentation. Logging Important Parameters. Examples of Logging Benefits. Visual Inspection. Power Resistors. Transmitting Capacitors. Vacuum Capacitors. Power Supply Components. Modulation Transformers and Reactors. Coils and RF Transformers. Power Tubes. Cleaning the Transmitter. Benefits. Inspection Opportunity. Use of Compressed Air. Cleaning the PA Tube Socket. Operational Inspection. Contactors and Relays. Circuit Breakers. Connection Points. Wiring Assemblies. Cavity Access Door(s). Klystron Maintenance. Integral Cavity Devices. External Cavity Devices. Cooling System. Magnet Assembly. Body Current Leak Path. POWER TUBES. Operating Environment. Dissipation. Physical Shock. Cooling System. Air Cooling. Water Cooling. Vapor-Phase Cooling. Operating Ambient Temperature. Cavity Back-Pressure. Warm-Up/Cool-Down Period. Replacing Tubes. Socket Assembly. Extending Tube Life. Filament Voltage Management. Example Procedure. Establishing the Emissions Floor. Tuning. When to Tune. Tuning By the Book. PREVENTING PROBLEMS THROUGH SYSTEM IMPROVEMENTS. Implementing Factory Updates. SPARE PARTS CONSIDERATIONS. Developing a Spare Parts List for Each System. CONTROLLING THE OPERATING ENVIRONMENT. Importance of Temperature Control. Proper Design of An Air-Flow System. Examples of Air-Flow Designs. Water-Based Cooling Systems. Air Filter Considerations. Environmental Control. TROUBLESHOOTING TRANSMISSION EQUIPMENT: DISCUSSION OF COMMON FAILURE MODES FOR HIGH POWER RF SYSTEMS, AND HOW TO RETURN THE TRANSMITTER TO SERVICE. BASIC TROUBLESHOOTING APPROACH. Analyze Each Step Before Your Take It. Take Your Time When Troubleshooting. Don't be Tempted by the "Quick Fix". Using Factory Support. Safety Practices When Troubleshooting. Remove AC Power. Discharge Capacitors. High Voltage Cautions. Troubleshooting Procedures. High Voltage Power Supply. RF Stages. Control/Logic Circuits. Methodical Approach to Troubleshooting. PLATE OVERLOAD FAULTS. Power Supply Problem. Determining the Fault Condition. Low Voltage Control Systems. Overload Sensor Placement. Examining the Most Likely Causes. PA Tube. Power Supply Components. Using the Process of Elimination. Removing PA Stage from Consideration. Eliminate Entire Stages at a Time. Safety Precautions. RF SYSTEM FAULTS. Grid Circuit Troubleshooting. Troubleshooting by Observation. Weak Link Component Stress. Substitution as a Troubleshooting Tool. Troubleshooting the PA Cavity. Identifying Key Cavity Elements. Physical Construction-vs.-Schematic. Determining Potential Failure Points. Mechanical Integrity. VSWR Overload Problems. Narrowing the Scope of the Problem. Identifying the Problem. AM System Failure Modes. POWER CONTROL FAULTS. Interlock Failures. Troubleshooting the Interlock System. Safety Precautions. Low Voltage/High Voltage Systems. Step-Start Failures. Thyristor Systems. Conventional Systems. Thyristor Control System Failures. Narrowing the Scope of Troubleshooting. Identifying the Defective Sub-System. Substitution as a Troubleshooting Tool. SAFETY: THE KEY TO STAYING ALIVE: IMPORTANT SAFETY CONSIDERATIONS FOR MAINTENANCE PERSONNEL AT ANY FACILITY. SAFETY IN THE WORK PLACE. Electrical Injuries. Effects on Current on Human Body. Let-Go Current Level. Current Path and Its Effects. Medical Attention Requirements. Circuit Protection Devices. Ground Fault Interrupter. Limitations of GFI Breakers. High Voltage Gloves. Applications. Potential Safety Hazard. Testing High Voltage Gloves. Example Problem with Gloves. Working with High Voltages. Safety Considerations. Electrical Hazards. RF Radiation Hazards. Current RF Radiation Limits. Beryllium Oxide Dust. First Aid. Treatment of Burns. OSHA SAFETY REGULATIONS. Scope of OSHA Requirements. Enforcement of Rules. Inspection Policies. Most Frequently Violated Rules. Checklist for OSHA Adherence. Regulations Relating to Electrical Facilities. Circuit Breaker Ratings. Circuit Breaker Markings. Nameplate Requirements. Extension Cords. Equipment Grounding. Where to Find Detailed OSHA Information. MANAGING SAFETY PRACTICES. Establishing a Facility Safety Program. Involvement of Management. Employee Involvement. Reporting Accidents. Preparing a Facility Safety Plan. Provide Leadership. Assign Responsibility. Identify Hazards. Train Employees. Maintain Good Records. Provide for First Aid Help. Encourage Employee Awareness. MANAGING THE PCB RISK: HOW TO MANAGE THE PROBLEM AND PAPERWORK RESULTING FROM EQUIPMENT USING OUTLAWED PCB DEVICES. SCOPE OF THE PROBLEM. History of the PCB Use. Trade Names. Types of Equipment Using PCBs. Equipment Free of PCBs. Health Effects of PCBs. Exposure Levels. Cumulative Effects. Related PCB Effects. Governmental Policies. EPA Ruling of 1982. Product Ban. REGULATIONS COVERING PCB PRODUCTS. Size Distinction. Small Capacitor. Large Capacitor. Small Transformer. Large Transformer. Record-Keeping Requirements. Use of PCB Components. Storage of PCB Components. Notifying Nearby Property Owners. Notifying the Local Fire Department. Required Inspections. Annual Reports. Labeling PCB Components. Label Sizes. Placement on the Device Itself. Placement on the Equipment Cabinet. Liquid-Cooled Rectifiers. DISPOSAL OF PCB DEVICES. Approved Disposal Site. Dealing with a Licensed Contractor. Approximate Cost of Disposal. Penalties for Improper Disposal. Clean-Up Fines. GLOSSARY. INDEX.

Dettagli dell'edizione

• Editore: CRC Press
• Data di pubblicazione: 1991
• Lingua: Inglese
• ISBN 10: 0849374111
• ISBN 13: 9780849374111
• Rilegatura: Copertina rigida
• Numero edizione: 1
• Numero di pagine: 470
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile