Sometimes, a bed heating failure will occur if the connector becomes stressed and continuity is broken. A momentary continuity break results in arching and melting within the connector. Usually, when this happens, the damage is confined to the little connector itself. The picture below identifies the connector in question.
- Unplug the pair of black wires from the mainboard.
- Unscrew the connector wire terminals and remove the connector from the wires. Examine the connector closely for signs of melting.
Sometimes, the evidence of connector damage is very subtle.
- If this happens repeatedly and you find yourself requiring a third or forth replacement connector, likely your wires are discolored with oxidation. You'll need to cut back those wires and strip clean new wire to seat into the connector.
- You'll no doubt want to make sure your mainboard has not been damaged. Look down into the port of the mainboard where you've removed the bed power connector. Examine the pins of the mainboard.
The picture below shows the heat bed pins of the mainboard. Note the melted base of the pin. Note also the color of them compared with the relatively silver, clean pristine pin just over to the left (yellow arrow). These two bed pins will make poor contact and repeatedly melt bed connectors. This mainboard requires replacement.
Once your mainboard pins, wire ends, and connector all check out or the appropriate one has been replaced, adding zip ties to those wires to keep them in place is critical. Refer to the guide linked below:
Secure ERC grey wire bundle