The JYMC-220B-I is a common DC brush motor speed controller used primarily in mini lathes like the CJ0618. While a single official "full" internal schematic is rarely published by the manufacturer, it is functionally equivalent to the KBIC-120 or SCR340 series controllers. Core Specifications Input Voltage: 230 VAC (50/60 Hz). Output Voltage: 0–180 VDC. Rated Current: 12 ADC (Armature DC).
Control Type: Silicon Controlled Rectifier (SCR) or Thyristor-based speed regulation. Terminal Connections (Wiring Diagram)
The board typically features the following labeled terminals:
The JYMC-220B-I is a widely used motor speed controller frequently found in mini-lathes, such as the Sieg C2/C3 and their various brand equivalents like Grizzly or Harbor Freight. Finding a "full" schematic for this specific board is essential for DIY repairs, as these controllers often fail due to component fatigue or motor stalls. Overview of the JYMC-220B-I Controller Go to product viewer dialog for this item.
This board is a Pulse Width Modulation (PWM) DC motor speed controller. It converts AC input (typically 220V or 110V depending on the specific sub-model) into a variable DC output to drive the lathe’s permanent magnet motor. Primary Function: Regulates the RPM of the spindle motor.
Key Protection: Features a current-limiting circuit to prevent motor burnout.
User Interface: Connected to a potentiometer for speed control and often a reverse/forward switch. Critical Components and Circuit Sections jymc220bi schematic full
While official technical manuals are often proprietary, the "full" circuit logic generally consists of the following sections: Rectification and Filtering:
AC mains enter through a fuse and pass through a bridge rectifier.
Large electrolytic capacitors (often rated for 400V) smooth the rectified DC. The Control IC:
Most versions of the JYMC-220B use a dedicated PWM control chip (like the SG3525 or similar) to generate the signal that drives the power transistors. The Power Stage:
This usually consists of two high-power MOSFETs or IGBTs mounted to a large heatsink. These are the most common points of failure if the lathe is overloaded. Feedback and Current Sensing:
A low-ohm power resistor (shunt) senses the current flowing to the motor. If it exceeds a preset threshold, the control IC reduces the PWM duty cycle to protect the board. Common Troubleshooting Tips The JYMC-220B-I is a common DC brush motor
If you are working with this board without a physical diagram in hand, check these common failure points first:
Blown Fuse: Always check the glass fuse on the board. If it’s black, a MOSFET likely shorted.
MOSFET Short: Use a multimeter to check for continuity between the Drain and Source pins. If they are shorted, the motor will likely run at full speed or not at all.
Potentiometer Failure: If the speed is erratic, the external 5k or 10k potentiometer may have a "dead spot" or worn-out wiper.
Relay Clicking: If you hear the relay click but the motor doesn't spin, check the brushes on the DC motor itself. Finding Documentation
For official firmware or setup guides for similar industrial controllers, you can sometimes find resources through the JuncAuto Download Center, though note that the JYMC series is often handled by specific machine tool manufacturers rather than general PLC providers. What is the JYMC220BI
+5V/12-24V DC IN
│
▼
[Voltage Regulator (3.3V)] ──▶ Logic VDD
│
▼
[STEP + DIR + UART RX/TX] ──▶ [TMC2209-like ASIC]
│ │
▼ ▼
[Charge Pump / Gate Driver] ◀── [Sense Resistors]
│
▼
[Power MOSFETs H-Bridge] ──▶ Motor Coils A+/A-, B+/B-
│
▼
[Current Sense / Overcurrent Protection]
First, let's decode the board. The JYMC220BI is typically an integrated Power Supply Unit (PSU) and LED driver board. It is commonly sourced from Chinese OEM manufacturers and found in budget-friendly LCD TVs from brands like Hisense, Element, Sceptre, or even generic commercial displays.
The "220" in the name often correlates to the input voltage compatibility (100-240V AC) or the maximum backlight current, while "BI" suggests a specific revision involving LED backlight inversion. Understanding this is critical: without a full schematic, diagnosing interdependent faults between the primary (high voltage AC side) and secondary (low voltage DC side) is nearly impossible.
Below is a text‑based recreation of the typical reference schematic you would find in the JYMC‑220BI datasheet. All component values are the most common for the 5 V‑fixed version; the 12 V version swaps a few resistors and a larger output capacitor.
| Ref | Part | Value / Description | Notes | |-----|------|---------------------|-------| | Vin | – | 4.5 V – 38 V | Connect to the raw supply. | | C1 | 100 µF electrolytic (X5R) | Input bulk capacitor | Placed as close as possible to the IC pins. | | L1 | 22 µH (ferrite core) | Integrated in‑package inductor (part of the chip) | Not a discrete part – drawn for illustration. | | D1 | SS34 (Schottky, 3 A, 40 V) | Free‑wheel diode | Must be placed with the cathode toward VOUT. | | C2 | 22 µF, 25 V X5R | Output bulk capacitor | Works together with the internal capacitor to meet ripple specs. | | C3 | 0.1 µF ceramic, 50 V | High‑frequency decoupling | Located right at the IC power pins. | | RFB | – | Internal (fixed) | In the 5 V version the feedback divider is inside the IC; for the adjustable version, replace with a resistor divider (R1, R2). | | IC | JYMC‑220BI | 5 V, 1 A buck regulator | Pin‑out described in section 4. | | GND | – | Ground plane | Keep the return path wide and low‑inductance. |
How the schematic looks in a schematic‑capture tool
Vin ---- C1 ----+----+--------------------+----> VOUT
| | |
| IC1 D1
| (JYMC‑220BI) |
| |--- SW (pin 3) ----+---|<---+
| | | |
| L1 (integrated) | |
| | | |
+----+--- GND ---------+----------+
| |
C3 C2
| |
GND GND
Tip: In a real PCB you will see a thermal pad on the bottom of the IC that should be soldered to a copper area (often connected to ground) to aid heat dissipation.
Below is a functional block diagram that abstracts the internal architecture (no copyrighted layout, only a conceptual view).
+ Vin (4.5‑38 V)
│
▼
┌─────────────┐
│ Power │ ← Input filter (CIN, optional L in)
│ Stage │
└─────┬───────┘
│
┌─────▼─────┐ ┌─────────────────┐
│ PWM │ →────►│ MOSFET (Q) │
│ Controller (IC) │ + Inductor L │───► VSW (switch node)
└─────┬─────┘ └───────┬─────────┘
│ │
┌─────▼─────┐ ┌─────▼─────┐
│ Feedback │◄───────│ DIODE │ (Schottky, fast recovery)
│ Network │ │ (D1) │
└─────┬─────┘ └─────┬─────┘
│ │
┌─────▼─────┐ ┌─────▼─────┐
│ Output │ │ Output │
│ Filter │ │ Capacitor│
│ (COUT) │ │ (COUT) │
└─────┬─────┘ └─────┬─────┘
│ │
▼ ▼
VOUT (5 V/12 V) GND