A microcomputer-based imaging system for instructing television troubleshooting has become available. It mainly consisted of an television troubleshooting expert system software and a digital image processing board installed in a 386[superscript]' IBM PC/AT microcomputer. The teaching images were grabbed by a CCD video camera and processed with PCA image database packages;The expert system developed for this study provided a knowledge base which followed the rules of "proceduralized problem-solving" and consisted of a knowledge base, an image database, and an inference engine. The knowledge base included a library of decision-making rules, frames of troubleshooting procedures, and frames of learning units. The image database contained test patterns, block diagrams, stage circuits, and symptomatic pictures. The inference engine included a frame and rule interpreter, user commands, and a screen interface. The decision-making rules were organized with 'IF-THEN" logic. In order to simplify the diagnosis procedure, four criteria (raster, picture, color, and sound) were applied to analyze a defective television symptom;An experiment was conducted to test the effectiveness of this prototype instruction system. Thirty-six students were selected from the department of Industrial Education, National Taiwan Normal University, and randomly assigned to two groups each with equal members. The experimental group learned television troubleshooting with a microcomputer and the developed courseware, while the control group used traditional instruments to learn television troubleshooting. They were both given pretest, posttest, and skill test during class sessions;The achievement differences between these two groups were analyzed with the SAS packages. There was a significant achievement difference between the control group and the experimental group in learning television troubleshooting knowledge and skills. In addition, the time consumption difference for troubleshooting a defective symptom also reached a significant level. It was possible to say that the microcomputer-based television troubleshooting instruction using image database was more effective than traditional teaching method. To improve this system, a complete software and update hardware were encouraged.