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故障现象:开机送带后,其他功能均正常,但在快进、倒带、加载、卸载时有伴音输出,不能实现静躁。分析与检修:录像机在静躁时应切断伴音输出。J25录像机静噪电路是受系统控制电脑块IC_(6001)(MN6743VRDH)脚输出电平控制,正常重放状态时脚应为低电平,静噪状态为高电平输出。根据原理图1可知:当工作在重放状态时IC_(6001)脚输出的低电平加至三极管QR_(4050)(MRN2404)的发射极,此时因有磁
Symptom: boot boot, the other functions are normal, but fast forward, rewind, load, uninstall audio output, can not achieve static. Analysis and Overhaul: VTR should cut off sound output when restless. J25 video recorder squelch circuit is controlled by the system control block IC_ (6001) (MN6743VRDH) pin output level control, normal playback state should be low when the pin, the mute state is high output. According to the schematic diagram 1, it can be seen that the low level output by IC_ (6001) is added to the emitter of transistor QR_ (4050) (MRN2404) when operating in the replay state,