Jymc220bi Schematic Full !exclusive!

The main power grid line feeds directly into the primary filtering block to scrub high-frequency noise and protect internal logic components.

A critical feature for mini lathes. It monitors the current draw of the motor. When a load is applied (e.g., a steel cutting tool engaging the workpiece), the motor wants to slow down. The IR Compensation circuit senses the increased current and automatically bumps up the output voltage to maintain a steady speed. Common Troubleshooting and Repairs

Sets the threshold for overload shutdown. Setting this too low causes the lathe to trip under minor loads; setting it too high risks burning out the motor armature during a tool jam.

Connects to the manual speed control dial. P1 serves as the circuit low side (0V Reference), P2 tracks the analog wiper voltage signal input (0 to +7V DC isolated tracking mode), and P3 delivers the high voltage side reference (+10V DC). The board expects a linear 4.7kΩ to 10kΩ potentiometer .

Connected in parallel across the DC motor output terminals (

Most JYMC boards feature small, adjustable blue or white potentiometers soldered directly to the board to fine-tune operations. Be very careful adjusting these while the board is live:

Uses high-current SCRs (often S8020L) and Diodes (D8020L) to rectify AC to DC and control the speed. Control Logic:

Look for swollen electrolytic capacitors or dark burn marks around the power resistors and rectifiers.

Drops the high voltage to a regulated +12VDC or +15VDC analog rail to fuel the timing ICs.

The JYMC-220BI speed control board is a staple in modern benchtop mini lathes and mills, such as those produced by Sieg, Grizzly, and Precision Matthews. Operating as a Pulse Width Modulation (PWM) controller, this board regulates the speed and torque of permanent magnet direct current (PMDC) motors.

1PC DC speed control board JYMC-220B-II 12A 115V lathe control board Go to product viewer dialog for this item. Input Voltage 230VAC ±10% (50/60 Hz) Input Voltage 115VAC ±10% (50/60 Hz) Output Voltage 0–180 VDC Output Voltage 0–110 VDC / 0–180 VDC Rated Current 12A DC Continuous Rated Current 12A DC Continuous Drive Technology SCR Thyrister Phase Control Drive Technology SCR Thyrister Phase Control Compatible Motors 450W – 1100W Brushed DC Compatible Motors 450W – 1100W Brushed DC The Full Architectural Schematic Breakdown

The schematic of the JYMC-220B-I is built around a pulse-width modulation (PWM) or SCR-based rectification system (often using components) to convert AC input into a variable DC output. AliExpress Control and Feedback Loop The board utilizes an LM324 quad operational amplifier