Research Of Fault Diagnosis System For Circuit Board Based On Dedicated Signal Acquisition Devices

With the rapid development of electronic technology, the scale of the board becomes more gigantic and integrated, at the same time the frequency of failure is also increasing. Carrying out manual testing at part that problems which may occur step by step is the mainly detection means in early circuit board fault diagnostician, and this manual method of detection is slow, inefficiency, at the same time, it requests operators to be experienced. Automatic fault detection and diagnosis of the circuit board is conducive to improve its automation level, accelerate the process of design, production and maintenance belong to modern electronic product and enhance the life of electronic devices, as we all know, this has great significance to automatic detection on board and fast maintenance for equipment.In this thesis, based on the characteristics of the tested circuit board, a circuit board fault diagnosis system that based on dedicated data collection devices is designed, the system responses in the comparison of the output signals in fault status and normal status, in next step, it works on the detection and localization of circuit board in fault status, then, this will be used to guide the latter part of the maintenance work. Dedicated signal acquisition equipment includes signal generation unit and signal acquisition unit. Signal generator unit generate variety of signal by control panel generating signal, and signal acquisition unit achieves the target that collecting signal by control panel for signal acquisition. In addition, the communication protocols between the various modules are designed based on the characteristics of the system, what makes data communications faster and more reliable.The thesis first introduces the background and development of the circuit board fault diagnosis technology, and then given the general design of the system, and then consists of a detailed exposition of the system from hardware aspect and software aspect. Acquisition and generation of analog and digital signal can be completed by dedicated signal acquisition equipment, and it will totally meet acquisition of diagnosis system about input signal and output signal, at the same time, the thesis gives explanation of signal generation circuit and signal acquisition circuit. Interface of software which is modular designed is designed as a main interface and several sub-interface which will be used for special circuit board. The operator can start the entire detection system, database, help system and enter the sub-interface through the main interface, while the self-test of the system can be done at the same time. Sub-interface are clear structured by different modules, what makes the system be easy to use and easily expandable. The whole software is friendly and easily expandable.Finally, with system design methodology in front of the thesis, the thesis designs systems for detecting input and output circuit, switching power supply and sequential logic circuit, and then the systems’detection methods are briefly introduced.