Practical Troubleshooting of Electronic Circuits for Engineers and Technicians

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<ul><li> 1. Technology Training that works Practical Troubleshooting of Electronic Circuits for Engineers and Technicians Technology Training that Workswww.idc-online.com/slideshare </li></ul> <p> 2. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Objectives Understand the technical meaning of failure Know the symptoms of failure Study the causes of failure Study Early Failure, Random Failure and Wear out Failure Know what is Failure Rate, Mean Time to Failure, Mean Time between Failure and Mean Time to Repair Technology Training that Workswww.idc-online.com/slideshare 3. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Symptoms Failure A deviation in the properties of a component or item from prescribed condition is considered as a fault Failure Curve Traditional bathtub curve indicates component life in three stages 4. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Symptoms Reliability Curve (generalized) First stage Failure rate begins high and decreases rapidly with time. This stage is known as Infant Mortality Period and has a Decreasing Failure Rate (DFR) Second stage State failure rate period, which is usually long also known as random failure period or useful life of the equipment Third stage Beyond useful life period, there is a gradual increase in failure rate. A period of ageing and wear out with increasing failure rate 5. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Equipment Failure Partial failures Resulting from deviation in characteristics or parameters beyond the specified limits Complete failure If characteristics deviate beyond specified limits causing complete breakdown Catastrophic failure A sudden and complete change in an equipment's performance Degradation failure Failures occurring gradually and in a partial manner Failed item: Completely inoperable Operable but no longer able to perform its intended function satisfactorily Serious deterioration made it unreliable 6. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Causes Classification Design Deficiency a) Little engineering efforts / changes in design b) Improper choice of components c) Upgrading of a part d) Inadequate information on failure analysis of components e) Insufficient design criteria f) Insufficient prototype testing for meeting both reliability and performance specification g) Excessive heat development inside equipment and lack of cooling h) Poor mechanical layout of components, assemblies and panels 7. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Causes Production Deficiency Improper / substandard purchase of material Unsuitable storage method and long storage period of components Absence of training programs to employees Negligence in performing environmental tests like temperature cycling, operation of equipment at elevated temperature for specified period Lack of proper working environment, ill-ventilated, poor illumination and dusty assembly shops Lack of inspection of goods, sampling tests and inspection Insufficient testing and inspection of finished product 8. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Assembly Errors Careless Storage and Transport Excessive vibrations and mechanical shocks during transportation Improper packaging Undue long storage of equipment Undetected errors in assembly by manufacturer / purchaser Improper matching of various signals used or generated by the components on the terminal board at the time of assembly Improper prescribed order of the components collected on the terminal board 9. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Improper Working Conditions Presence of abnormal severe conditions of speed, temperature etc. Using equipment without following manufacturer's instructions, warnings and cautions Inadequate maintenance policy and after sale service Usage of equipment beyond its lifetime Aging of the equipment Operator error Lack of preventive measures 10. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Types Early Failure Random Failure Wear out Failure 11. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Types a) Early Failure b) Random Failure c) Wear out Failure Poor quality control techniques during production Causes: Also known as Infant Failures, can be eliminated by de-bugging or burn-in process Weak and substandard components 12. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Types c) Wear out Failure Predominant during actual operation of system Occur at random, irregularly and unexpectedly Caused by sudden stress accumulations beyond specification of component Phase during which only chance failure occur is called useful life of the system Reliability techniques help to reduce occurrence of random failures b) Random Failure a) Early Failure 13. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Failure Types b) Random Failurec) Wear out Failure a) Early Failure Caused due to aging or wearing out of components Improper maintenance Need of preventive maintenance Period between two maintenances should be shorter than the mean wear out life of the system 14. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Some Useful Terms in Failure Failure Rate Failure Rate = f / T Where: f = number of failures during the test interval T = total test time Smaller the value of the failure rate, the higher is the reliability of the system Mean Time to Failure (MTTF) For one transistor used in the system, MTTF = 1 / 5 * 10 -5 = 20,000 hours 15. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Some Useful Terms in Failure Mean Time to Failure (MTTF) Calculated on the basis of the results of life testing of components MTTF = Total test time / number of components Mean Time between Failures (MTBF) MTBF = 1 / Failure rate = T / f Where: f = number of failures during the test interval T= total test time 16. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Some Useful Terms in Failure Mean Time to Repair (MTTR) Average time required to bring a system from a failed state to an operational state. Defined as the total corrective maintenance time divided by the total number of corrective maintenance actions during a given period of time. 17. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare Summary A deviation in the properties of the component or item from prescribed condition is considered as a fault. A state of fault is denoted by the term failure Component life is divided into three stages. Infant Mortality Period, Random Failure Period and Wear out stage Production deficiency, Processing deficiency, Assembly errors, inadequate storage and transport conditions Failure Rate, Mean Time to Failure, Mean Time between Failure and Mean Time to Repair Important mathematical terms in failure Some of the major causes of failure: 18. Technology Training that worksTechnology Training that Workswww.idc-online.com/slideshare DO YOU WANT TO KNOW MORE? If you are interested in further training or information, please visit: http://idc-online.com/slideshare </p>