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笔者遇到的一台D25送修彩电奇特的故障现象是:有时声音和图像均正常;有时却有光栅,无图像无伴音,屏幕上无噪点,十分干净。故障的出现完全没规律,是随机现象。分析与检修:按常规的检修方法判断,故障应在高频头和中放电路。在故障出现时,用干扰法,将干扰信号引入中放电路输入端,机子有反应,说明中放电路是正常的,故障应收缩到高频头部分。此时,认真测量高频头的各工作电压发现:B_L、B_H、B_U电压均为0十分反
I encountered a D25 repair TV peculiar malfunction phenomenon is: sometimes the sound and images are normal; sometimes there are rasters, no images without sound, no noise on the screen, very clean. The emergence of failure is completely irregular, is a random phenomenon. Analysis and overhaul: According to the conventional method of maintenance judgment, the fault should be in the tuner and the discharge circuit. In the event of failure, with the interference method, the interference signal is introduced into the input circuit in the release circuit, the machine reaction, indicating that the discharge circuit is normal, the fault should be reduced to the first part of the high frequency. At this point, the working voltage of the tuner was carefully measured: B_L, B_H and B_U voltages were all 0