The PWM Control CircuitAt the heart of the schematic is a dedicated PWM controller chip (often a TL494 or similar SG series IC). This chip generates a high-frequency signal. By varying the "duty cycle" of this signal via the front-panel potentiometer, the user tells the board how much power to send to the motor.
Based on common board layouts for this series, follow these standard terminal assignments: Connect to your 220V AC power source. jymc220bi schematic 2021