| Pin Name | Function | Description | | :--- | :--- | :--- | | | Power Supply | +3.3V to 5V input. | | GND | Ground | Common ground reference. | | CS | Chip Select | Active Low. Enables the LCD controller. | | RESET | Reset | Active Low. Resets the controller. | | DC/RS | Data/Command | Selects whether data sent is a command (Low) or data (High). | | MOSI (SDA) | SPI Data | Serial data input from the microcontroller. | | SCK (SCL) | SPI Clock | Serial clock input. | | LED | Backlight Control | Connect to VCC for "Always On" or use PWM for dimming. | | MISO | SPI Output | (Optional) Serial data output. Often not populated or used. |
Usually employs Silicon Controlled Rectifiers (SCRs) or power transistors mounted to a large aluminum heat sink to pulse-width modulate the power pushed to the motor's armature.
Below is a functional block diagram that abstracts the internal architecture (no copyrighted layout, only a conceptual view). jymc220bi schematic full
JYMC-220B-I (Commonly replaces older JYMC-220A-I and SCR340 units) ±plus or minus 10% (50/60 Hz single-phase alternating current) Output Voltage 0 to 180V DC variable output voltage Rated Output Current 12A DC continuous current capacity Compatible Motors Permanent magnet DC brush motors up to 1100W power draw Physical Footprint Approximately 110 mm 92 mm base size ⚡ Full Schematic Topology & Circuit Blocks
: Divided into three distinct terminal hookups: High ( Vcccap V sub c c end-sub ) : Positive voltage rail output. | Pin Name | Function | Description |
Drops the high voltage to a regulated +12VDC or +15VDC analog rail to fuel the timing ICs.
: Delivers 0–180V DC variable power to the brush motor. If your lathe spins backward relative to your control switch position, swap these two lines. Enables the LCD controller
While the full schematic remains elusive, this guide provides you with the identity, specifications, key resources, and a practical diagnostic path to get your machine back in working order.
Note: Typically uses a standard linear 5kΩ or 10kΩ potentiometer. Diagnostic Trimming: On-Board Potentiometers
: Caps the top-end ceiling voltage (typically calibrated right at 180V DC) to ensure the lathe motor never exceeds its safe maximum RPM rating.