¶ Phenomenon:
During the preparation for printing, the heat bed temperature is not at 0 °C, but it does not change after setting a higher temperature.
If the heat bed temperature is indicated as 0 °C, please see this Troubleshooting of heat bed not heating up | Bambu Lab Wiki page for assistance.
¶ Causes & Solutions
The bed temperature is not 0. This means that the temperature sensor of the heat bed is normal, which, in turn, means that the heat bed may be faulty, the power supply may be faulty, or the control signal transmission is failing.
- Check the resistance value of the heat bed. If the resistance value is abnormal, it indicates that the heat bed may have burnt components or an open circuit, and the heat bed needs to be replaced;
- Check the connection status of the power cable and the cable connecting the MC board with the AC power board. If poor contact is found, reconnect the cable(s);
- Check the conduction of the power cable of the heat bed and confirm that the power cable is not damaged. If it is damaged, replace the power cable (or replace the heat bed);
- Check the AC power board. If any components on the AC power board are damaged, or the heat bed and power cord are confirmed to be normal, replace the AC power board.
¶ Safety warning and Machine state before starting operation
1. The heat bed is directly heated by the mains electricity, and there is a danger of high voltage. It is necessary to ensure that troubleshooting is carried out with the power off.
2. If it is found that the heat bed (AC power board) is burnt, check whether the AC power board (heat bed) is in good condition at the same time.
¶ Tools needed
- H2.0 hex key
- Multimeter
- Tweezers
¶ Operation guides
¶ Step 1 - Raise the heat bed
In order to facilitate this process, we need to raise the heat bed: tilt the printer, and pull the Z-axis belt to raise the heat bed to 2/3 of the way up.
¶ Step 2 - Check the resistance of the heat bed
Remove the 2 screws as shown in the picture below, remove the cover, and use a multimeter to test the resistance value of the two terminals. If the resistance value is between 40 and 60 ohms, the heat bed is normal, and you can go to the next step; otherwise, the heat bed needs to be replaced.
（Click Heat bed to view how to replace the heat bed）
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¶ Step 3 - Check the cable connections
Remove the rear panel and the cable cover, and check the connection status of the power cable and the cable connecting the MC board with the AC power board to confirm that the connection is normal without looseness or skew. Then, go to the next step.
（Click Cable cover to view how to disassemble the cable cover）
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¶ Step 4 - Check the heat bed power cable
Remove the two blue silicone sleeves and test the resistance value with a multimeter. If the resistance value is between 40 and 60 ohms, the power cable is normal, and you can go to the next step. If the value is different, it means that the power cable is faulty and needs to be replaced (or the heat bed needs to be replaced).
（Click Heat bed to view how to replace the heat bed）
Caution: After measuring, please restore the blue silicone sleeves to keep the plugs insulated.
¶ Step 5 - Check the AC power board
If the above steps are normal, it can be basically confirmed that the AC power board is faulty and needs to be replaced.
Of course, if the AC power board has visible damage, this can also be used to determine that the AC power board is damaged and needs to be replaced.
（Click AC board to view how to replace the AC board）