All kinds of good and bad electrical faults in terms of probability include the following situations:
1. Poor contact. Poor contact between the board and the slot, when the cable is broken internally, when the cable is broken, the plug and the terminal are not in good contact, and the components are soldered, etc.
2. The signal is disturbed. For digital circuits, the fault will only appear under certain conditions. It may be that the interference is too much, which affects the control system to make mistakes, and there may be individual component parameters or overall performance parameters of the circuit board. Changes, the anti-interference ability is approaching a critical point, and failure occurs;
3. The thermal stability of the components is not good. From the point of view of a large number of maintenance practices, the thermal stability of the electrolytic capacitors first is not good, followed by other capacitors, transistors, diodes, ICs, resistors, etc .;
4. Moisture and dust accumulation on the circuit board. Moisture and dust will conduct electricity and have a resistance effect, and the resistance value will change during the process of thermal expansion and contraction. This resistance value will have a parallel effect with other components. When this effect is stronger, the circuit parameters will be changed to make the fault occur;
5. Software is also one of the considerations. Many parameters in the circuit are adjusted by software. The threshold of some parameters is adjusted too low, which is in a critical range. When the operating conditions of the machine meet the reason for the software to determine the fault, the alarm Appeared.
