I have a base model Ender 5 with the silent v4.2.7 board.

Earlier this week during an overnight print, I came in to find it unfinished and powered off. I turned it back and it complained about an outage. When I started warming the hotend, it squealed and turned itself back off and then back on.

Now anytime, I try to warm up the hotend, I get the same.

I set up the printer to give data me debugging data via the console in Pronterface and in Simplify3D. I don't receive any kind of error, the printer just powers off and then back on.

I'm hoping that the thermister is just dead and I can replace it easily enough. What I'm afraid of is that the board itself is dead. BTW, I am able to warm up the bed with no problem, just not the hot end. Any insight would be appreciated.

  • $\begingroup$ You could check whether your thermistor is reading values by removing it from the heater block and holding your fingers over it with the printer on to see if the hotend temperature value changes. $\endgroup$
    – FEA42
    Jan 3 at 17:55
  • $\begingroup$ It's possible that your bed heater has (partly) shorted out so that when it turns on, the power supply shuts down from overload. It's also possible that the power supply has partly failed so that it cannot produce enough current to run the heater. I think it's unlikely that the board itself has failed. $\endgroup$
    – DoxyLover
    Jan 3 at 19:45
  • $\begingroup$ re: FEA42 it reads the temperature at -14C. I think that's a little low. ;) $\endgroup$
    – JSEvans
    Jan 3 at 22:18
  • $\begingroup$ re: DoxyLover I checked the heater core with my multimeter. It definitely has resistance and isn't shorted out. That doesn't mean that there isn't a fault in the board itself. I've only had the v4.2.7 board for 2-3 weeks. I ordered a new thermister since they are fairly cheap. Hopefully, that's all it is. $\endgroup$
    – JSEvans
    Jan 3 at 22:21

"Heater core" wires are not the same as thermistor wires, are they?

Check if thermistor is properly connected?

Reading -14 C in my case always pointed a disconnection of thermistor. (I didn't had a case of broken one so far.) In case of short it would probably show som max temperature (my guess, I dont want to try), but it is always good to check if wires are do not touch each other and are properly insulated?

Measure thermistor's resistance

If you are able to use multimeter, then:

  • disconnect thermistor from the printer board
  • set multimeter to resistance measurement (200k Ohms)
  • connect thermistor and multimeter using wires - the ones having aligator clips would be the best
  • read resistance measurent

My spare shows 97k Ohms in room conditions. So value should be high (you may refer to specs sheet of given type when in doubt).

Check that hotend is actually powered

If thermistor is OK, then indeed the hotend powering may be broken. Ths definitely require skills and may introduce many risks to electronics and maybe even to your health - but if you are skilled enough, you may measure with voltmeter if there is correct voltage provided to the hotend. For example the MOSFET on the board may be broken (I already replaced one in the past for my heated bed).

  • $\begingroup$ I got the new thermister in on Friday. Yes, that was the culprit. I'm just glad it wasn't the board itself. $\endgroup$
    – JSEvans
    Jan 11 at 20:44

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