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例1.故障现象:M2024型打印机开机后,机板指示灯不亮,整机无任何反应。 分析检修:测量打印机电源+36V和+5V输出端电压,+36V正常,+5V输出端电压为0V,说明是由于无+5V电源输出,使得主控电路不工作,从而造成了打印机不能正常工作。再测量+5V输出端对地阻值正常,说明故障发生在+5V电源电路,测量整流桥V0B2的输出端电压为正常值9V,表明整流滤波电路正常,检查电源调整管VT23正常,说明是由于VT23无启动电压,导致VT23处于截止状态,引起VT23+5V输出。启动电路由IG_2及其外围元件组成,测量IC_2的启
Example 1. Symptom: After the M2024 printer is powered on, the indicator on the board is off and the machine does not respond. Analysis and maintenance: measuring printer power +36 V and +5 V output voltage, +36 V normal, +5 V output voltage is 0V, indicating that the absence of +5 V power output, making the main control circuit does not work, resulting in the printer does not work . +5 V output voltage measurement again to normal resistance, indicating that the fault occurred in the +5 V power supply circuit, measuring the output voltage rectifier bridge V0B2 normal 9V, indicating that the rectifier filter circuit is normal, check the power regulator VT23 normal, indicating that due to VT23 no start-up voltage, resulting in the VT23 is off, causing the VT23 +5 V output. Starting circuit consists of IG_2 and its peripheral components, measuring IC_2 Kai