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故障现象:在用2～3年后,频道开始出现“逃台”现象,对电视机重新进行频道搜索,刚开始还可以看到节目,但随着收看时间的增加,故障越来越严重,最后出现了VL、VH和U频段的低端电视信号能收到,而部分高端信号收不到。修理方法:对于这种故障,应首先用万用表检查调谐电压的最大值VTmax是否是+32V,即对线路图4中电容CA13两端进行测量。这时测得电压只有二十几伏,刚开始怀疑是稳压管NQA32击穿,但在线测量
Symptoms: In 2 to 3 years, the channel began to appear “escape Taiwan” phenomenon, the television channel search again, the beginning can also see the show, but with the increase of viewing time, the fault is more serious, The last appeared VL, VH and U band of low-end television signals can be received, while some high-end signal can not receive. Repair method: For this kind of fault, first check the maximum voltage VTmax of the tuning voltage is + 32V with a multimeter, that is, measure the two ends of the capacitor CA13 in the circuit diagram 4. At this time the measured voltage is only twenty volts, just started to suspect that the regulator NQA32 breakdown, but the online measurement