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故障现象 录像机盒带加载到位后,便自动倒带至带头,然后盒带被弹出带仓外,其它操作无效。 分析与检修 机器自动倒带说明CPU接收到带尾低电平检测信号,其原因有:(1)磁带走到带尾或磁带破损,使带盒灯发出的红外光穿过磁带被光敏管接收到。(2)检测电路有故障。试更换录像带后故障依旧,这说明故障在检测电路。 由于找不到该型号录像机的电原理图,只好根据录像机的电路结构进行检查。从主线路板上可以看到该机的CPU型号为MN67434VRSG,与松下HD-82录像机的CPU型号一样。带盒检测电路也与松下HD-82一致,如附图所示。
Symptom After the video cassette is loaded, it is automatically rewound to the leading edge, and then the cassette is ejected outside the cassette. All other operations are invalid. Analysis and Overhaul of the Machine Automatic Rewinding Description The CPU receives the low end detection signal for the following reasons: (1) The tape comes to the end of the tape or the tape is broken, so that the infrared light emitted by the tape cassette lamp is received by the photosensitive tube through the tape To (2) the detection circuit is faulty. After the test tape replacement failure still shows that the fault detection circuit. Since it can not find the electrical schematic of the VCR, it has to be checked according to the circuit structure of the VCR. From the main circuit board can see the machine’s CPU model MN67434VRSG, and the Panasonic HD-82 VCR’s CPU model. With box detection circuit is also consistent with the Panasonic HD-82, as shown in the figure.