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故障一现象:闭上电源开关后,面屏指示灯无光亮,各连接线无问题.故障分析与排除:从现象看指示灯无光亮,推测故障应出在打印机的电源部位.卸下访问盖检查,发现F_1250/5A保险管烧坏,说明低通滤波器或开关电源部分有严重短路.测试滤波电容C_1、C_2、C_3和全桥D_1290～310V整流完好.再测试开关控制回路(如下图),T_2双向可控硅一极被击穿.更换一支参数相近的4A/600V元件,故障依旧.继续检测场效应开关元件Q_1/2SK727.用500型表置于R×1kΩ档,红表笔接漏极,黑表笔接源极,阴值数为无穷大,再将黑笔换接栅极,读数为“0”则为损坏.更换F_1和Q_1/2SK727.2SK727市面上难以买到,可用参数相近的8N90管代换.装
Fault phenomenon: close the power switch, the screen lights no light, the cable no problem. Failure Analysis and Troubleshooting: From the phenomenon of light there is no light, suggesting that the fault should be in the printer’s power supply. Remove the access cover Check and found F_1250 / 5A fuse burned, indicating a serious short-circuit the low-pass filter or switching power supply part of the test filter capacitor C_1, C_2, C_3 and full bridge D_1290 ~ 310V rectified intact test switch control circuit (as shown below) , T_2 one-way triacs were breakdown. Replace a similar parameter 4A / 600V components, the fault still. Continue to detect the field effect switching element Q_1 / 2SK727. With 500 table placed in R × 1kΩ file, Drain, the black pen then the source, the negative number is infinite, then the black pen for the grid, reading “0” is damaged. Replace F_1 and Q_1 / 2SK727.2SK727 difficult to buy on the market, the available parameters are similar The 8N90 tube substitution