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[例1]故障现象 接通电源开关,电源指示灯亮,插入带盒,按重放键,磁带加载中途停止,重新接通电源开关后磁带接着卸载,按快进或倒带键正常,按出盒键带盒能正常弹出。 分析与检修 根据磁带加载中途停止这一现象,估计机械传动机或系统控制微处理器电路有问题。拆开机壳,插入带盒,按下重放键,磁带加载中途停止时观察到加载电机不转动,随后电源指示灯熄灭。重新接通电源开关,用500型万用表黑表笔接地、红表笔监测系统控制微处理器IC801(63)脚(LOD MCTL)输出为低电平OV,按下重放键后(63)脚立即从OV变为高电平5V,并在加载中途停止时立即输出低电平OV。由上述检
[Example 1] Symptom Turn on the power switch, the power indicator light, insert the cassette, press the playback key, stop the tape loading, re-turn the power switch after the tape unloading, press the fast forward or rewind button normal, press the Box key box can pop up normally. Analysis and Overhaul According to the phenomenon of halting tape loading, it is estimated that there is a problem with the mechanical conveyor or the system control microprocessor circuit. Disassemble the case, insert the cassette, press the playback key, the loading of the motor stopped midway when the loading motor is not observed, then the power light goes out. Re-connect the power switch, connect the black stylus of Model 500 to the ground, and the red pen monitor system controls the output of the microprocessor IC801 (63) pin (LOD MCTL) to low level OV. Press the playback button (63) OV goes high 5V and outputs low OV immediately when the load stops. By the above seizure