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1 故障现象 开机后按下电源开关,D_2灯不亮。 2 分析检修 D_2灯电路是由四部分组成:控制电路、D_2灯灯丝预热电路、起辉电路及D_2灯稳流电路组成。其工作过程如下:开机后按下电源开关,微机送一低电位使继电器RY_1有电,RY_1工作使RY_1 -1接通灯丝3、8两端有3VAC电压,灯丝预热。继电器RY_1 -2接通280VAC经过D10向电容C3电。几秒后,微机送一高电位使RY_1断电,同时送一低电位使RY_2有电,此时灯丝预热结束,即RY_1 -1断开,RY_1 -3
1 fault phenomenon Press the power switch after power on, D_2 light does not shine. 2 analysis and maintenance D_2 lamp circuit is composed of four parts: control circuit, D_2 lamp filament preheat circuit, starter circuit and D_2 lamp steady current circuit. The working process is as follows: After the power is turned on, the power switch is pressed, the microcomputer sends a low potential to make the relay RY_1 have electricity, and RY_1 works to make the RY_1 -1 turn on the filaments 3, 8 at both ends with 3VAC voltage, and the filament is preheated. Relay RY_1 -2 turns on 280VAC through D10 to capacitor C3. After a few seconds, the microcomputer sends a high potential to power down RY_1 and sends a low potential to make RY_2 powered. At this time, the filament warms up and RY_1 -1 turns off, RY_1 -3