Hotbed too hot.

[FugBucker]

Hi, printer has been working well for the last week. But now the Hotbed keeps overheating. It keeps climbing until it gets to 150 and then the error msg saying max temp. Even in manual mode with the Hotbed temp turned off it still heats up. I'm guessing it's the thermistor not cutting in. Is there a way I can test it...?

[zhangxueyou]

Please unplug the wire of hotbed thermistor, and test the resistance of hotbed thermistor with multimeter under normal temperature.

[abulafi]

Hi, printer has been working well for the last week. But now the Hotbed keeps overheating. It keeps climbing until it gets to 150 and then the error msg saying max temp. Even in manual mode with the Hotbed temp turned off it still heats up. I'm guessing it's the thermistor not cutting in. Is there a way I can test it...?

I don't think it is related to the thermistor (since the controller is reading the temperature right and displaying it on the screen). The same happened to me and it was related to the heat bed MOSFET, it became dead short.
Check the MOSFET with a multimeter while the printer is off after disconnecting the heat bed wires, if the pins are short then yep, you need to replace it.

[FugBucker]

Hovering between 136 - 137...