论文部分内容阅读
由于各种因素的影响,电镜电路的故障时有发生。本文就JEM—100CX型电镜物镜(OL)电路发生的故障,介绍一下该部分电路的分析及其修复过程,供同道们参考。一、故障现象:按下功能选择键[MAG],调节聚焦旋钮,图像不发生变化,无法聚焦。二、检查与分析:按下[MAG]键,用万用表测量OL测试端电压,将三组聚焦旋钮(COARSE、MEDIUM、FINE)均逆时针旋转到底,得电压最小值V_min为1.41V;顺时针旋转到底,得电压最大值V_max为2.13V。测试端的标准电压值应为V_min=0.46V;V_max=2.13V。实际测量值与标准值比较,V_min增加了两倍以上。物镜系统的电路(图1)主要由物镜基准电压、物镜电流稳定、物镜电流控制等几部分组成。物镜测试端电压是由电阻R_21(1Ω)的两端引出的,端电压的上升,表明物镜线圈中的电流也增加,考虑到调节聚焦旋钮,图像不随之变化,又说明线圈中电流失去控制。由此估计故障出在物镜电流控制部分或电流稳
Due to various factors, the failure of the electron microscope circuit has occurred. This article on the JEM-100CX-type electron microscope (OL) circuit failure, introduce the analysis of the circuit and the repair process for the fellow reference. First, the fault phenomenon: Press the function selection key [MAG], adjust the focus knob, the image does not change, unable to focus. Second, the inspection and analysis: Press the [MAG] key, measuring OL test terminal voltage with a multimeter, the three groups of focus knob (COARSE, MEDIUM, FINE) are rotated counterclockwise in the end, the minimum voltage V_min 1.41V; Rotate in the end, the maximum voltage V_max of 2.13V. The standard test voltage should be V_min = 0.46V; V_max = 2.13V. The actual measured value compared with the standard value, V_min more than doubled. The objective lens system of the circuit (Figure 1) mainly by the objective lens voltage, objective current stability, objective current control and other components. The voltage at the objective test terminal is drawn from both ends of the resistor R_21 (1Ω). The rise of the terminal voltage indicates that the current in the objective lens coil also increases. Taking into account the adjustment of the focus knob, the image does not change and the current in the coil is out of control. Thus it is estimated that the failure of the objective part of the current control or current stability