JSP-based Changhong SF2170E Fault Diagnosis Expert Systems

Fault tree analysis (FTA) is a analysis method which uses logic to identify faults vividly in the two aspects--- the qualitative analysis and the quantitative analysis. By using this analysis method, a logic diagram, a tree of logic, can be obtained which clearly shows the relationships between faults and all the possible elements causing the faults, and it can also show the causality relations between the structure of the system and each component. FTA is a diagnosis method with a clear train of thought, vividness and strong logic, which is applied in many fields, such as CNC, Automatic train Operation System, Turbine Generator System, Automobile Brake System and so on.Traditional television fault diagnosis requires technicians to artificially analyze and identify the causes, so it requires maintenance workers to know clearly the television structure and to have comparatively high professional qualities. With the rapid development of electronic technology, more and more advanced technologies are used in television, which result in more and more complicated television structure, so more and more causes leading to television faults arise. Theses faults are more and more diverse, and the common maintenance workers cannot keep up with the development of television technology, so they can only depend on their experience to diagnose the faults, which causes the low-maintenance efficiency and effect.This thesis focuses on applying FTA in the field of television faults diagnosis and how to use this analysis method to assist maintenance workers in diagnosing the television faults. The thesis takes "Changhong SF2170E" for an example to develop a "Changhong SF2170E Fault Diagnosis Expert System", which analyses the main faults layer by layer to identify the fault components by establishing a fault tree. The thesis puts emphasis on the switching power supply failure of "Changhong SF2170E" television. The switching power supply failure has five different failure phenomena, so the first step is to establish different fault trees according to the different failure phenomena, and then experts take the fault probability of each low-level event as a known quantity, which is based on their own theory and experience, to analyses quantitatively the fault tree of the switching power supply and calculate the key importance degree of the low-level events of the different failure phenomena. At last according to the key importance degree, the relevant fault components are ranked from big to small to determine the overhaul order.