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故障现象:电源指示灯亮,液晶屏有显示,但操作面板按键均无反应。分析与排除:此机原为雷击所为,用户送他处修理后即出现故障。接手此机,估计故障还是出在电源板上,所以重点对电源板上的相关电压进行检测。通电测电源板 CN402插座的±12 V、+24 V 电压正常,+5 V 电压为+2.8 V 左右,显然+5 V 电压不正常,此部分电路见图1。拆下电源板,空载通电,测+5 V处电压正常,用40 Ω/15 W 的电阻接在+5 V 输出端
Symptom: Power indicator light, LCD screen display, but the operation panel buttons are not responding. Analysis and Exclusion: This machine was originally due to lightning, the user sent him elsewhere after repair failure. Take over this machine, it is estimated that the fault is still on the power board, so focus on the power board to detect the relevant voltage. The power supply board CN402 socket ± 12 V, +24 V voltage is normal, +5 V voltage is about +2.8 V, obviously +5 V voltage is not normal, this part of the circuit shown in Figure 1. Remove the power board, no-load power supply, the voltage measurement at +5 V normal, with 40 Ω / 15 W resistor connected to the +5 V output