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pHs—3酸度计是一种十进制数字显示仪器,仪器中大量采用了P—MOS集成电路。集成电路极易因使用不当而损坏。集成电路损坏的常见故障是仪器的不计数。本文针对这一问题介绍故障原因分析、故障部位的查找和排除故障的方法。一、故障原因分析故障现象:当仪器的选择键置“pH”档时,只显示“0.000”pH值,调节定位旋钮不起作用,用标准直流电位差计输入标准电势后,仪器也不计数。从图1可知,导致不计数的原因有:(1)前置pH放大级损坏时,输入信号不能传至以后各级;(2)积分器有问题,来自前置pH放大级的模拟量信号就无法转换为相应的数字量信号,(3)时钟振荡器不振荡,计数器将设有计数脉冲;(4)控制电路中某一控制开关或控制门坏,前置级的信号在传输过程中中断、积分器不积分或使计数器闭锁,从而
pHs-3 pH meter is a decimal digital display instrument, the instrument used in a large number of P-MOS integrated circuits. Integrated circuits can easily be damaged by improper use. A common failure of integrated circuits is the instrument’s non-counting. This article addresses the issue of failure analysis, fault location and troubleshooting methods. First, the cause of the malfunction Analysis of symptoms: When the instrument selection key set “pH” file, only shows the “0.000” pH value, adjust the positioning knob does not work, with a standard DC potentiometer input standard potentiometer, the instrument does not count . As can be seen from Fig. 1, the reasons leading to no counting are as follows: (1) The input signal can not be transmitted to subsequent stages when the pre-amplified pH stage is damaged; (2) there is a problem with the integrator, (3) the clock oscillator does not oscillate, the counter will be provided with a counting pulse; (4) a control circuit in the control switch or control the door is bad, the pre-class signal in the transmission process Interrupt, integrator does not integrate or make the counter latch, thus