Causes and Analysis of Uneven Fan Speed:
Rectifier Tube Issues: If one of the four rectifier tubes fails, it may cause uneven fan speed during operation.
Poor Contact of the Variable Resistor: The variable resistor is installed on the control panel. With frequent use, the resistor may develop poor contact, affecting its adjustment effect and leading to unstable fan speed.
Motor Rotor and Rectifier Issues: The motor rotor and rectifier may become unstable due to uneven carbon dust or carbon brushes. Check the fan’s variable resistor, and if the resistance value changes with adjustments, the potentiometer is likely functioning properly. For issues with large currents in the two tubes, you can check by tightening screws and welding wires. If loose, it is necessary to inspect the two tubes for faults.
Silicon-Controlled Rectifier (SCR) Failure: The SCR may have issues like open circuits, poor contact, or short circuits, all of which can affect the fan’s ability to run at a uniform speed.