开机电视机不起动,且测得300 v电压正常,+B无输出,关机后测得300 V电压不下降。这时用万用表Rx1档,黑表笔接开关管基极,红表笔接开关管发射极一测,有时能听到“吱”的一声响,回头再测300 V电压已消失,即可判定起动电阻已开路(启动电阻接在开关管基极与+300V之间,常见的有:56kΩ、120 kΩ、240 Turn on the TV does not start, and the measured voltage is normal 300v, + B no output, measured after shutdown 300V voltage does not drop. At this time with the multimeter Rx1 file, the black pen connected to the base of the switch, the red pen then switch the emitter of a test, and sometimes can hear the “squeak” sound, look back 300 V voltage has disappeared, you can determine the starting resistance Has been open (start resistance connected to the switch base and +300 V, common are: 56kΩ, 120 kΩ, 240