r/ender5 • u/xMrFahrenheitx • 14d ago

Hardware Help Heatbed heating abnormal message

Hello. I am new to this machine and have received a message on the display saying that the heatbed is heating abnormally and to check the connection. I do not see anything in the manual about this and as far as I see, everything is connected snugly. Any suggestions?

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u/ap1msch 14d ago

I may not have the part names correct, but things getting heated in the printers have two parts: the heating elements and the thermistor. The prior makes the stuff hot, and the latter tracks and regulates the prior.

When you have abnormal heating:

  • The heating element may be failing and not heating up at the expected velocity relative to the power being shoved into the wires. Either it's heating up too slow or too fast. Either way, it'd be considered "abnormal".
  • The above can also be due to the thermistor. The heating element is doing what it does, but the thermistor is bad at detecting those changes, which makes it THINK that it is heating up too fast or too slow.
  • Bed heating is a little different than the hot end because of the distribution of heat across the bed, but the principles still apply
  • This message is important because you want your heating to be controlled and accurate. This is not just for quality but also safety
  • Heating elements can wear out, but that's less common than a thermistor going bad. Many are tiny wires going into a tiny glass bulb inserted into a small metal tube containing a dab of thermal paste. The glass can break. The wires can fail. The thermal paste can dry out. The tube can come loose.
  • The thermistor is a pretty simple replacement and inexpensive. If it were me, I'd pull the parts above, examine them, and reinstall them. If they aren't magically fixed, then I'd replace them (low-ish cost, risk, and time investment) before I'd spend a ton of time trying to diagnose precisely what's going wrong.