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故障现象:“三无”。检修:用100W 灯泡作假负载试机,+B(+110V)正常,于是重点检查行扫描电路。主要对“行变”T761次级③、⑤、⑦、⑧脚外接整流二极管及滤波电容进行检测,无异常。仔细对次级各路负载逐一检查,发现D761负极所接三极管 Q791(2SD882Q)在路极间正反向电阻值偏小,取下后用万用表 R×1kΩ档测量已呈击穿性损坏。相关电路见图1。该晶体管与 ZD791、D791、D792、C791、R791组成稳压电路,从 T761③脚
Symptoms: “three no.” Maintenance: 100W light bulb for load test machine, + B (+ 110V) normal, so check the line scanning circuit. The main “line change” T761 secondary ③, ⑤, ⑦, ⑧ feet external rectifier diodes and filter capacitors were tested, no abnormalities. Careful inspection of the secondary load one by one carefully and found that the positive and negative resistance of the transistor Q791 (2SD882Q) connected to the D761 cathode is too small, measured with a multimeter R × 1kΩ file has been taken after the breakdown of the breakdown has been damaged. Related circuit shown in Figure 1. The transistor and ZD791, D791, D792, C791, R791 form a voltage regulator circuit, from the T761 ③ foot