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实例4 机型:长城JTC471—ZF彩电故障现象:光栅正常,收看远地台信号时图像很淡,伴音偏小;但收看本市强信号电台节目时则图像发生扭曲,伴音有失真现象。分析与梭修:从图像和伴音的质量都变差这一点看,故障在高、中频公共通道上;而从收看强信号时出现图像扭曲、伴音失真这一点分析,可能是中放AGC或高放AGC电路有故障。 1.检测图像中放集成块IC101(D7607AP)各脚(包括中放AGC)的直流工作电压,无明显异常。微调中频载频调谐回路L103的磁芯,故障无明显改善。
Example 4 Model: Great Wall JTC471-ZF color TV Fault phenomenon: grating normal, far away from the station to see the signal when the image is very light, with a small sound; but watch the city strong signal radio program distorted images, sound distortion. Analysis and shuttlecock: From the point of view that the quality of the image and the sound are worse, the fault is on the high and medium frequency common channels. However, when the strong signal is viewed, the image distortions and the sound distortion may be analyzed by AGC or high Put AGC circuit fault. 1. Check the DC working voltage of the IC101 (D7607AP) integrated block in the image (including the AGC). There is no obvious abnormality. Fine adjustment of the carrier frequency L103 carrier frequency tuning circuit core, no significant improvement in fault.