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故障现象:接通电源,开关置观察位置时,描笔马上偏向一侧,调整基线电位器,描笔刚一接近中间位置,马上又偏向另一侧,无法将描笔调至中心位置。开关置记录位置时,打定标,打出的标记呈尖脉冲形状。分析检修:电源部分、位置反馈部分、放大及功放部分,其中任何一部分不正常都有可能导致发生本故障。首先检查电源电路,用万用表测电源部分的输出电压均在正常值范围。然后检查放大部分,用 DT830数字万用表测前置放大部分的静态输出电压为0V,测后级放大器的静态输出也约为0V,说明前后级放大部分均正常。从电路图中可以看出,限幅放大器 YS3的输出应
Symptoms: Turn on the power, the switch set observation position, stroke pen immediately side, adjust the baseline potentiometer, stroke pen just close to the middle position, and then turn to the other side, can not be transferred to the center position. When the switch is set to record the position, the mark is marked and the marked mark is sharp pulse shape. Analysis and Maintenance: Power part, position feedback part, amplification and power amplifier part, any part of which is not normal may lead to the occurrence of the fault. First check the power circuit, with a multimeter to measure the power part of the output voltage are in the normal range. And then check the magnification part, with the DT830 digital multimeter to measure the preamplified part of the static output voltage is 0V, measured after the level of the amplifier static output is also about 0V, indicating the magnification of the front and rear stage are normal. As can be seen from the circuit diagram, limiting amplifier YS3 output should be