¶ Fault Symptoms
During heated bed heating, the touch screen displays the following Klipper error:
Heater heater_bed not heating at expected rate.
¶ Possible Causes
- The ambient temperature around the printer is below 25°C.
- The rear fan is turned on before the heated bed reaches the target temperature.
- The power supply voltage selector is set incorrectly.
- The heated bed thermistor wire or heated bed cable is damaged.
- The heated bed cable connector is loose or has poor contact.
- The heated bed thermistor connector or heated bed cable connector on the mainboard is loose.
- The heated bed module connection terminal is loose.
- The heated bed output voltage from the mainboard is abnormal.
¶ Tools Required
- Phillips screwdriver
- 2.0 mm Allen key
- Multimeter (for measuring output voltage)
¶ Troubleshooting Steps
¶ Preliminary Checks
Before performing further troubleshooting, check the following factors to ensure that the heated bed heating conditions and fan settings are appropriate.
-
Ambient Temperature
If the ambient temperature around the printer is below 25°C, it is recommended to install an enclosure to reduce heat loss and maintain a stable chamber temperature.
Recommended enclosure dimensions:
- Neptune 4 Max: 658 × 980 × 955 mm
- Neptune 4 Plus: 580 × 890 × 855 mm
-
Rear Fan Speed
A high rear fan speed can accelerate heat loss from the heated bed.
Do not turn on the rear fan before the heated bed reaches the target temperature.
If the heated bed still fails to heat properly after making the above adjustments, continue with the following troubleshooting steps.
¶ 1. Check and Adjust the Power Supply Voltage Setting
- Turn off the printer and unplug the power cord.
- Locate the power supply voltage selector on the side of the printer.
Note: Some printer batches have the voltage selector preset before shipment. If a sticker has been placed over the voltage selector, skip this step and continue with the following troubleshooting steps.
- Check whether the power supply voltage is set correctly according to the local mains voltage.
Important: Before adjusting the voltage selector, make sure the printer is turned off and the power cord is unplugged.
Select the appropriate voltage setting according to the local mains voltage:
- For a local mains voltage of approximately 110–120 V, select the 115 V setting.
- For a local mains voltage of approximately 220–240 V, select the 230 V setting.
Warning: Incorrectly setting the power supply voltage may prevent the printer from operating properly and may damage the power supply components.
- If the power supply voltage is set incorrectly, adjust it to the correct setting, reconnect the power cord, and turn on the printer to test the heated bed.
- If the power supply voltage is already set correctly, continue with the following troubleshooting steps.
¶ 2. Check the Heated Bed Cable for Damage
Inspect the heated bed cable at the rear of the heated bed that connects to the mainboard. Check for the following conditions:
- Damaged insulation
- Burn marks
- Broken wires
- Abnormal bending or deformation
If the heated bed cable is damaged, replace the entire heated bed assembly.
¶ 3. Check the Heated Bed Connections
Note: Turn off the printer and unplug the power cord before performing the following checks.
- Remove the drawer.
Note: This step applies only to the Neptune 4 Max. The drawer does not need to be removed on the Neptune 4 Plus.
- Use a 2.0 mm Allen key to remove the 20 screws securing the bottom cover.
- Slowly open the bottom cover and disconnect the mainboard cooling fan connector.
- Check whether the heated bed thermistor wire is loose, and disconnect and reconnect the TB0 connector.
-
Check the heated bed cable between the mainboard and the heated bed heating module, as well as the wiring connection at the heated bed heating module.
-
If the wiring connection is loose, use a Phillips screwdriver to tighten the screws securing the heated bed heating module wires.
After disconnecting and reconnecting the heated bed thermistor wire and tightening the heated bed heating module wiring screws, reinstall all removed printer components.
Turn on the printer and heat the heated bed. Check whether the error message disappears and whether the heated bed heating function has returned to normal.
- If the heated bed works normally: Troubleshooting is complete.
- If the problem persists: Continue with the following troubleshooting steps.
¶ 4. Check Whether the Mainboard Heated Bed Output Is Approximately 24 V DC
Note:
A multimeter is required for this step. If you do not have a multimeter, skip this step.
The printer must remain powered on while measuring the voltage. Do not touch other electronic components, and take care to avoid short circuits.
- Connect the power cord and turn on the printer.
- On the touch screen, select Prepare > Temperature, and set the heated bed temperature.
- Measure the voltage at the heated bed output terminal on the mainboard while the heated bed is heating.
Normal: The heated bed output terminal on the mainboard should provide approximately 24 V DC while the heated bed is heating.
Abnormal:
- No 24 V output: The mainboard may be faulty.
- Abnormally fluctuating voltage: The mainboard or power supply may be faulty.
¶ Contact Technical Support
If the problem persists after completing all the troubleshooting steps above, contact Technical Support at 3dp@elegoo.com and provide the following information:
- Is the power supply voltage set correctly?
- Is the heated bed cable loose or damaged?
- Are the mainboard heated bed thermistor connector and heated bed module connection terminal loose?
- Does the mainboard heated bed output provide approximately 24 V DC, and is the output voltage stable? (If you do not have a multimeter, skip this step.)
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