((exclusive)) | Jymc220bi Schematic Full

If you are on a deadline, stop searching for two hours and spend $15 on a replacement board from an online parts vendor. Time is money. However, if you are learning or the board is irreplaceable, focus on identifying the PWM controller's datasheet (e.g., LD7575) rather than the entire board schematic. That single datasheet provides 80% of the circuit logic.

Silicon Controlled Rectifier (SCR) or Thyristor-based speed regulation. Terminal Connections (Wiring Diagram) jymc220bi schematic full

| Pin | Name | Description | Typical Voltage | |-----|------|-------------|-----------------| | | VIN | Input voltage (4.5 – 38 V) | – | | 2 | GND | Ground (common) | 0 V | | 3 | SW | Switching node (connects to the internal MOSFET) | Pulses between VIN and GND | | 4 | FB | Feedback (fixed internally for 5 V/12 V; external for adjustable) | ≈ 0.6 V (reference) | | 5 | EN | Enable pin (active‑high). Pull high to turn on; pull low to shut down. | 0 V or 3.3 V | | 6 | SS | Soft‑start control (optional). Usually left unconnected; pulling low reduces inrush current. | – | | 7 | TEMP | Internal temperature sensor (not usually accessed). | – | If you are on a deadline, stop searching

If the board is completely dead, check the glass fuse on the board or in the machine's control panel. That single datasheet provides 80% of the circuit logic

If the speed is erratic, the external 5k or 10k potentiometer may have a "dead spot" or worn-out wiper.

The heart of the schematic is the COG (Chip on Glass) driver.