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故障现象:一通电源,功能键置准备档,记录笔上下乱打,数秒钟后笔单偏。调移位电位器,笔毫无反应。分析检修:引起单偏故障的除电源有误外,多见于放大系统及位置反馈系统故障,而位置反馈系统故障其现象虽也是单偏,但当调节W_4移位电位器时,笔能大幅度上下移动。见图1。于此断定,本故障一定是出在放大系统。先测放大部分的电源为12.5V,即电源正常。因为前置放大部分与后级放大之间是阻容耦合的,于此得出前置放大器以前的电路与本故障无关,问题在后级放大器及其以后部分。查
Symptoms: a power supply, the function key set ready file, record pen up and down chaos, a few seconds after the pen single side. Adjust the shift potentiometer, pen no response. Analysis and maintenance: In addition to single-partial failure caused by the power supply error, more common in the amplification system and position feedback system failure, while the position feedback system failure, although the phenomenon is also one-way, but when adjusting W_4 displacement potentiometer, pen can significantly Moving up and down. see picture 1. In this assertion, the fault must be in the amplification system. First test the majority of the power supply is 12.5V, that is, the power supply is normal. Because preamplifier part and after amplification between the RC is capacitively coupled, thus concluded that the preamplifier before the circuit has nothing to do with the fault, the problem in the amplifier and its subsequent part. check