Brief introduction to the common fault repair of conductivity meter

Many people know that the conductivity meter is a digital display instrument for measuring the conductivity of aqueous solutions. A common problem is that the conductivity meter often shows unstable values and jumps when used in the southern rainy season. How to solve it?
As we all know, the conductivity meter is a digital display instrument. Because the input signal of this type of instrument is very small, the stability of the work is very important to it. The conductivity of the conductivity meter in the rainy weather may be related to this level. Circuit related, if the instrument does not provide a circuit diagram, it is known from the physical object that the input stage of the instrument consists of two op amp ICs (LM324N, CA3140E) and peripheral components. Both ICs and printed circuit boards are connected by IC sockets. Although the connection method is convenient to install, there is a big drawback, that is, the contact resistance and the thermoelectric potential formed by the connector terminals thereof change according to changes in environmental humidity, temperature, dust and plugging pressure, and the like. It is of a random nature. Under normal circumstances, it is impossible to fully compensate. This situation will definitely affect the stability of the system, causing "warm drift" and "time drift" of the additional output.
In addition, during the transmission of the signal, the active elastic contact of the IC socket may cause "hidden danger". After combining the above conditions, the IC socket must be removed first, and then the two op amp ICs should be directly soldered to the printed circuit board. In order to avoid the stray interference signal entering from the input end of the instrument and destroying the stable operation of the input stage, the input line (the platinum black electrode used for measurement) and the input line of the instrument are changed to have a shielding layer and a printed circuit. The board's "public place" is connected.
After adopting the above method, the work of the conductivity instrument can be stable and reliable, and the fault of the numerical value jump of the instrument can be completely solved.