9 methods for fault diagnosis of multimeter and other instruments
1. Tapping hand pressure method
It is common to encounter the phenomenon of instruments running intermittently, which is mostly caused by contact or virtual soldering. For this situation, tapping and hand pressure methods can be used. The so-called "tapping" refers to gently tapping the plug-in board or component with a small rubber mallet or other tapping object on the possible faulty part to see if it will cause errors or shutdown faults. The so-called 'manual pressure' refers to the process of turning off the power and then manually pressing the plugged components, plugs, and sockets back firmly when a fault occurs, and then turning on the machine to see if it can eliminate the fault. If it is found that knocking the casing once is normal, but then knocking it again is not normal, it is best to first re plug all the connectors and try again. If it is troublesome and unsuccessful, we have to find another way.
2. Observation method
3. Exclusion method
The so-called elimination method is a method of determining the cause of faults by plugging and unplugging some plug-in boards and components inside the machine. When the instrument returns to normal after removing a certain plug-in board or component, it indicates that the fault occurred there.
4. Substitution method
5. Comparison method
6. Heating and cooling method
Sometimes, when the instrument works for a long time or when the working environment temperature is high in summer, it will malfunction. After shutting down and checking, it will work normally. After stopping for a period of time and then restarting, it will work normally again, and then the malfunction will occur again after a while. This phenomenon is caused by poor performance of individual ICs or components, and the high-temperature characteristic parameters do not meet the required specifications. To identify the cause of the malfunction, the temperature rise and fall method can be used. The so-called cooling refers to using cotton fibers to wipe anhydrous alcohol on the possible faulty area when a malfunction occurs, to cool it down and observe whether the malfunction is eliminated. The so-called temperature rise refers to artificially raising the ambient temperature, such as placing an electric soldering iron close to the suspicious area (be careful not to raise the temperature too high and damage normal components) to see if a fault occurs.
7. Shoulder riding technique
8. Capacitor bypass method
9. State adjustment method
