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例1 [现象]据用户反映,在收看闭路电视节目时,正是雷雨天气,突然一声巨雷,电视荧光屏一闪,声光全无,同时听到机内“叭”的一声响。 [分析与检查]正在收看的电视机,雷击时出现三无,一般是雷电进入电网,在火线与零线之间造成很强的脉冲电流,损坏电视机电源。雷电通过电视天线进入高频调谐器一般不会出现三无。打开机盖观察,发现4 A/250 V熔断器熔断,电源滤波电容器C902、C903炸裂。经测量,全桥硅堆VC901及电阻R901(2.2 Ω/5 w)均损坏。 [措施]按原型号更换损坏的元器件后,电视机恢复正常。
Example 1 [Phenomenon] According to users, watching closed-circuit television programs, it is thunderstorms, a sudden thunder and lightning, TV screen flash, no sound and light, while hearing the machine “horn ” sound. [Analysis and Inspection] Watching TV, there are three when the lightning strike, lightning is generally into the power grid, causing a very strong pulse current between the live line and the zero line, damaging the TV power supply. Lightning through the TV antenna into the high-frequency tuner generally does not appear three no. Open the lid observation and found 4 A / 250 V fuse blown, power filter capacitor C902, C903 burst. The measured full bridge silicon stack VC901 and resistor R901 (2.2 Ω / 5 w) are damaged. [Action] The TV returns to normal after replacing damaged parts by the original model number.