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故障现一台金星C37-401型彩电开机后无光栅、无伴音,并伴有吱吱叫声。故障检修打开后盖检查电源保险丝F901完好。通电后测量开关电源108V直流电压只有30V左右,54V直流电压也只有十几伏,因而怀疑行输出电路可能有严重短路。用万用表R×10挡,红表笔接地,黑表笔接行输出管BG_(702)的c极,表针摆动很小,证明行输出管良好。断开过压保护可控硅BG_(704)控制级,电视机仍未恢复正常。由此可推断故障可能部位:(1)保护取样厚膜块CP_(701);(2)BG_(704)可控硅本身损坏;(3)CP70l①脚供电电压太高;(4)场输出电流过大使CP70l④脚电压偏高。在没有HM7103厚膜情况下以先判断BG_(704)可
Trouble is a Venus C37-401-type color TV boot, no grating, no sound, accompanied by a cheep sound. Troubleshooting Open the back cover Check the power fuse F901 intact. After measuring the power switch 108V DC voltage of only about 30V, 54V DC voltage only a dozen volts, and therefore suspected line output circuit may have a serious short circuit. Use a multimeter R × 10 block, the red pen grounding, black pen output line BG_ (702) of the c pole, needle swing very small, that the line output tube well. Disconnect overvoltage protection thyristor BG_ (704) control level, the TV has not returned to normal. It can be inferred that the possible parts of the fault: (1) protection sampling thick film block CP_ (701); (2) BG_ (704) thyristor itself damaged; (3) CP70l ① foot supply voltage is too high; (4) field output current Ambassador CP70l ④ feet high voltage. In the absence of HM7103 thick film to judge BG_ (704) can be