故障现象 1:开机后便烧断保险丝管,电源无法供电工作。 分析与维修:开机检查时发现保险管F1已经烧断,测功率电阻R1(4.7Ω)已经开路,当换上电阻后开机时,功率电阻正常,保险丝仍烧断。根据电源工作原理及经验判断,是故障后级的输入端或保护电路中的某个元件击穿短路所造成的。经测得电源整流桥(D1～D4)中的半桥已经击穿,顺着线路继续查找,发现电源开关管Q1(2SC3152)的c-e极也已击穿。因为Q1开关管是起着电压保护及导控作用,它的耐压根据设计要求应保证在700V以上,而一般的彩色电视机开关管就很 Symptom 1: Fuse tube blown after power on, the power supply can not work. Analysis and Maintenance: Power-on inspection found fuse F1 has been blown, the measured power resistance R1 (4.7Ω) has been open, when the switch on the power, the power resistance is normal, the fuse is still blown. According to the working principle of power and experience to judge, is the fault level input or protection circuit in a component breakdown caused by short circuit. The measured half bridge in the rectifier bridge (D1 ~ D4) has been breakdown, follow the line to find and found that the power switch Q1 (2SC3152) c-e pole has also been breakdown. Because the Q1 switch is a voltage protection and pilot control, its pressure according to the design requirements should be guaranteed at 700V above, and the general color TV switch is very