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故障:开机指示灯亮,“二次”环能开机。检修:因缺乏图纸,观察电路查得:CPU/N001(CHT1201)(42)脚为开/关机控制脚,测其电压始终为4.2 V 高电平,按遥控开机无反应。把 N001(42)脚断开对地强行开机,这时各受控电路电压输出正常,但屏幕无反应(行不能起振)。测 N301(OM8839)(12)、(27)脚供电正常,(40)脚行推动输出为1.9 V(较正常3.5 V 低)。用强行开机来确定故障部位的这一目的无法达到。略一思考:不能强行开机可能因为 N301要在 CPU正常工作后与之取得通讯才能正常工作(这一思路在CPU 正常工作后得到证实)。现在重点的检修应该放在CPU 的检修上。
Failure: boot light, “secondary” ring can boot. Overhaul: due to lack of drawings, the observation circuit: CPU / N001 (CHT1201) (42) feet on / off control pin, the measured voltage is always 4.2 V high, according to the remote boot no response. The N001 (42) feet off to force the boot, then the controlled circuit voltage output is normal, but the screen no response (line can not start). Test N301 (OM8839) (12), (27) feet normal power supply, (40) feet push the output of 1.9 V (lower than the normal 3.5 V). With forcibly boot to determine the failure of this purpose can not be achieved. A little thought: can not force boot may be because the N301 to get the CPU to work properly to get communication to work (this idea is verified after the CPU is working properly). Now the focus of overhaul should be on the CPU overhaul.