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故障现象:开机呈“三无”,瞬间有“吱吱”声。检修方法:根据现象分析,该故障可能是由于电源电路或其负载电路发生故障,使保护电路动作所致。用万用表测得开关电源+B端对地电阻仅3Ω左右,说明行输出电路确实有短路故障。先查行输出管Q605,已经击穿;再查开关电源其他负载电路与行扫描电路其他元器件均正常,更换行输出管后,试机一切正常。随后,将机芯装好再次试机时又出现“三无”故障现象。再次测量+B端对地
Symptom: boot was “three noes”, an instant “creak” sound. Maintenance methods: According to the phenomenon analysis, the fault may be due to the power circuit or load circuit failure, so that protection circuit action. Measured with a multimeter + B switching power supply side ground resistance is only about 3Ω, indicating that the output circuit does have a short circuit fault. First check the output tube Q605, has been breakdown; check the other switching power supply load circuit and other scanning circuit components are normal, replace the output tube, the test machine everything is normal. Subsequently, the movement installed again when the test machine again “three no” failure phenomenon. Measure again + B terminal to ground