Skip to main content

Common Mainboard Precautions

General Guidelines Before Use​

Power Off Operation

Before installing the mainboard, plugging or unplugging driver modules, connecting motor wires, fan wires, endstop wires, probe wires, heater wires, thermistor wires, CAN/USB cables, or adjusting jumper caps, please completely shut down the printer and disconnect the power supply. Do not connect wires, plug or unplug modules, or touch exposed terminals while the power is on.

Installation Suggestions
  • Before the first installation, verify the mainboard model, supply voltage, driver model, and wiring diagram. Do not mix pin descriptions from different mainboard models.
  • Prioritize using factory-provided wiring harnesses, terminals, and adapter boards. It is not recommended to modify wires or connect exposed terminals yourself.
  • After wiring is complete, perform a visual inspection to ensure there are no reverse insertions, misalignments, short circuits, pinched wires, damaged insulation, metal shavings, or loose screws on the mainboard.
  • For the first power-on, it is recommended to connect only essential devices. After confirming the mainboard can connect normally, gradually connect peripherals such as drivers, motors, fans, endstops, and probes. Always disconnect power before adding or replacing any peripheral.

Mainboard Installation Precautions​

  1. The mainboard should be fixed on insulating support pillars or manufacturer-provided mounting positions. Do not let the back of the mainboard directly contact the metal frame.
  2. Fixing screws should not be too long to avoid hitting components or circuits on the back of the mainboard.
  3. Before installation, clean up metal shavings, broken wire ends, and extra screws inside the electronics compartment to prevent short circuits after power-up.
  4. Keep the mainboard's heat dissipation area well-ventilated. Ensure driver heatsinks and fans are not obstructed by wiring harnesses.
  5. Wiring harnesses entering the electronics compartment should have strain relief and be fixed to prevent force from cable chains or external pulling from acting directly on the mainboard terminals.

Power Supply Precautions​

Power Supply Safety

Do not disassemble the power supply casing, modify the mains wiring, or touch the internal components of the power supply. For issues related to the power input, mains-heated bed, SSR, and high-voltage terminals, please contact after-sales support or a professional.

  1. The mainboard input voltage must match the device specifications, commonly 24V. Do not connect 24V to a 5V/12V interface.
  2. Before connecting the power supply, ensure the positive and negative terminals are correct. Connect VIN+ / V+ to the power supply positive terminal, and GND / V- to the power supply negative terminal.
  3. Do not use the mainboard's 5V output to power an upper computer like a Raspberry Pi or FLY-π, unless explicitly supported by the corresponding product documentation.
  4. High-current loads (heated bed, heater cartridge, high-power fan) should use appropriate wire gauges and reliable terminals. Do not continue using terminals that are loose, blackened, deformed, or emitting an odor.
  5. Route power cables, heated bed cables, and heater cables separately from USB/CAN/endstop/probe signal cables as much as possible to reduce interference.

Driver and Motor Wiring Precautions​

  1. Disconnect power before inserting the driver module, and confirm the driver orientation matches the mainboard silkscreen.
  2. Configure UART/SPI jumper caps according to the mainboard instructions. Incorrect jumper cap positions can prevent driver communication.
  3. Do not plug or unplug stepper motor cables while the power is on. Hot-plugging may damage the driver chip.
  4. Confirm the motor A/B phase wiring sequence using the motor datasheet or manufacturer's wiring harness. If a motor only vibrates, fails to rotate, or makes abnormal noises, first disconnect power to check the wiring sequence and connector.
  5. Fill in driver parameters like sense_resistor and run_current according to the driver manufacturer's documentation, not just based on guessing the chip model.

Mainboard Driver Pin Description​

FLY mainboard driver installation and driver jumper description:

Loading...

Mainboard PWM Interface Description​

  • The signal pins between the RGB interface and the BL-TOUCH interface are all PWM interfaces.
  • Some signal pins on the EXP header can be used as PWM signal pins. Please refer to the corresponding mainboard documentation and pin definitions.
  • Servo signals also use PWM pins. Note that if you are using a servo larger than MG90S, you must use an external 5V power supply and share a common ground with the mainboard, otherwise it may damage the mainboard.
PWM Interface Note

A PWM signal pin is not a power pin. Before connecting peripherals like servos, LEDs, or speed control modules, verify the peripheral's supply voltage, signal level, and GND common ground requirements. Do not directly connect an external power supply output to a mainboard signal pin.

Fan and Low-Voltage Output Precautions​

  1. The fan's rated voltage must match the fan header voltage. For example, connect a 24V fan to a 24V fan header, and a 5V fan to a 5V fan header.
  2. Before sharing a single fan header with multiple fans, confirm that the header's MOSFET and power trace can handle the total current.
  3. Do not arbitrarily connect the tachometer wires or PWM speed control wires of 3-wire/4-wire fans to regular power or signal pins.
  4. Immediately stop using a fan if its wiring insulation is damaged, the connector is loose, the fan makes abnormal noises, has abnormal heating, or emits an odor.

Fan Explanation​

Fan Risks

Some fans, due to their internal driver design, back-voltage characteristics, or abnormal wiring sequence, may cause damage to the mainboard's fan MOSFET, fan header, or main control circuit over long-term use. If a problematic fan is found, immediately stop using it and do not continue testing it connected to the mainboard fan header.

Power Off Operation

Before connecting, replacing, or checking fan wiring, please completely shut down the printer and disconnect the power supply. Do not plug or unplug fan cables, adjust voltage jumpers, or touch exposed terminals while the power is on.

Safety Troubleshooting Suggestions:

  1. After disconnecting power, confirm the fan's rated voltage matches the mainboard fan header voltage (e.g., 24V fan to 24V header, 5V fan to 5V header).
  2. After disconnecting power, check the fan's positive/negative terminals, connector orientation, and wiring condition. Do not continue using if you find damaged insulation, crushed wires, burn marks, odor, or loose connectors.
  3. Prioritize cross-testing using manufacturer-provided or known-good fans and wiring harnesses.
  4. During power-on testing, only adjust the fan speed via the web interface or console. Observe whether the fan starts/stops normally, makes abnormal noises, exhibits abnormal heating, or emits odors.
  5. If a fan vibrates abnormally or stalls at low speed, has significant abnormal noise at high speed, or if the mainboard/header becomes abnormally hot when the fan is connected, immediately disconnect power and stop using the fan.
  6. It is not recommended for ordinary users to touch the exposed terminals of the fan header for electrical testing. If further testing is needed, please contact after-sales or a professional.

Endstop Signal Description​

Endstop Wiring

Before inspecting or replacing endstops, TAP, optical endstops, proximity switches, filament runout sensors, etc., please completely shut down the printer and disconnect the power supply. Incorrectly connecting VCC, GND, and Signal on a 3-wire endstop can damage the mainboard, toolboard, or driver.

  • Some endstop switches output a 5V signal, which could damage the main control chip on products like toolboards.
  • Please ensure the endstop signal voltage is strictly within the 0~3.3V range.
  • For standard 2-wire micro-switch endstops, only connect GND and Signal. The 5V pin on the mainboard endstop header is usually left unconnected.
  • Before using 3-wire endstops, optical endstops, hall effect endstops, or proximity switches, first confirm the wiring sequence and output level. If unsure, do not connect them directly to the mainboard.
  • Before performing the first homing operation, use QUERY_ENDSTOPS to check the endstop status. Do not execute G28 if the status is incorrect.

For detailed endstop wiring and configuration, please refer to: Endstop Related.

Probe and Sensor Wiring Precautions​

  1. Before wiring probes like BLTouch, TAP, Klicky, EDDY, or inductive probes, confirm the supply voltage, signal level, and pin definitions.
  2. Do not connect a 24V probe signal directly to a mainboard signal pin that only supports 3.3V/5V.
  3. Connect thermistors, PT100/PT1000, and thermocouple modules to their corresponding interfaces. Do not mix them with fan headers, heater headers, or endstop headers.
  4. Do not plug or unplug accelerometer modules like ADXL/LIS2DW while the power is on. Keep SPI/I2C wiring as short as possible and route them away from motor and heater cables.

USB / CAN Communication Wiring Precautions​

  1. Route USB/CAN communication cables as far away as possible from motor cables, heated bed cables, heater cables, and power cables.
  2. CAN-H must connect to CAN-H, and CAN-L must connect to CAN-L. Do not cross them.
  3. Termination resistors are required at both ends of the CAN bus. Prioritize using onboard jumper caps, DIP switches, or factory-terminated interfaces to enable them.
  4. Disconnect power before adjusting the CAN wiring sequence, termination resistors, or shielding.

For detailed CAN troubleshooting, please refer to: CAN Network and ID Search.

Loading...