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提示:本文中开关管基极电流的求解方法请参阅本刊连载文章《从电子、家用电器元器件到基本电路(十八)》(P24/12/2000)。一台金星C498—1型彩电出现“三无”故障。经检查发现开关管V720(2SD2294)已击穿,脉宽控制管V725(BC548)集电极虚焊。查电源负载部分无直流短路和开路现象,查开关管集电极尖峰脉冲吸收电路正常。将V725补焊后,又将脉宽控制电容C714(47 μF/25V)和误差取样滤波电容C745(4.7μF/50 V)全部换新
Hint: In this paper, the solution of the base current of the switch transistor can be found in the article entitled “From Electronics, Home Appliances Components to Basic Circuits (18)” (P24 / 12/2000). A Venus C498-1 color TV “three no” failure. The inspection found that the switch V720 (2SD2294) has breakdown, pulse width control tube V725 (BC548) collector Weld. Check the load part of the power without DC short circuit and open phenomenon, check the switch tube collector spike pulse absorption circuit is normal. The V725 welding, pulse width control capacitor C714 (47 μF / 25V) and error sampling filter capacitor C745 (4.7μF / 50 V) all new