hotend thermal runaway  

Re: hotend thermal runaway

Didnt you do anything wit heatblok last few weeks?
Because i had this error on mk2s because of "too tightly" litte screw which fix thermistor inside heatblok.
On mk3 I tear off one of thermistor wire while cleaning nozzle (and heatblik) with steel brush.

Re: hotend thermal runaway

set your extruder at about 60mm above the heatbed,
preheat to PLA temperatures,
allow temperature to stabilise

move the extruder to the right hand side and see if the temperature starts to fall... if it does, then the chances are that your heater wires have started to break through constant flexing.

if nothing changes, try wiggling the cable bundle at the back of the extruder carriage to see if this causes the temperature to fall.

what is happening is that your thermistor is reporting a temperature below target, the einsy controller is trying to heat the extruder, but the temperature is not responding,
after a short while, the safety features kick in, and declare thermal runaway, rather than leaving your printer heating until something bursts into flames...

other possibilities are
heater plug not secure on the einsy,
heater not secure in the extruder heat block
faulty einsy
faulty power supply, (this should also affect the heatbed)

no doubt if I have forgotten something, someone else will chip in! 🙂

best wishes, Joan

Re: hotend thermal runaway

thermistor problems normally cause:
Mintemp error! (thermistor not plugged in, or wires broken)
Maxtemp error! (thermistor wires short circuit!)

regards Joan

Re: hotend thermal runaway

Yes but if wires touch each other like in my case there is only bigger resistivity and that cause "lower measurred" temp.

Re: hotend thermal runaway

Thanks for all the suggestions.

To check for loose connections, I tried:
- Moving the head 60mm above the bed
- Set the temperature to 210 and waiting until it stabilizes. It never completely stabilizing (around 0.2 degree over or under)
- Move the head to the other side. No temperature change
- Move the cables, no temperature change.
- I tried the connectors again, looks good.

When the head is at temperature then a red diode is blinking staidly on the Einsy board

I tried to keep it at 210 for 5 min, it worked fine.
I then tried to turn the fan to 100% and wait. It failed with HOTEND THERMAL RUNAWAY after about 5 min.
I tried again (210 degree, and fan, no moving). I could not make it fail, but I did get temperature variations. See attached.

It seems to be struggling with the temperature at times. Some of the times where it was below the 210 the red diode on the Einsy board was off.

I can not understand it....

Regards,
Søren

Re: hotend thermal runaway

wierd... time to chat to support?

Joan

Re: hotend thermal runaway

Your graph is awesome for control teory teching. Because PID (i think only PI) contoler has wrong settings, I think it is too agresive and setpoint is for long time much higher than actual temp. If I can tune this controler I will lower the D and increase I constant. Try to Tune PID from setings several time in normal condition (livingroom temperature, not hotter!) without draught. After each tuning make the same graph and evaluate progress.

Re: hotend thermal runaway

I got in touch with Prusa Support.

The issue turned out to be a failure in the power-panic feature. Once I disconnected the black and white wire from the power supply the error no-longer happened. (So the printer was suspecting an imminent power failure and therefor turned of the heaters, (makes sense), but it should not later report this as a thermal-runaway).

The printer seems to be working fine with the power-panic wire disconnected.

Thanks for the suggestions.

Re: hotend thermal runaway

Re: hotend thermal runaway

Quote soren.a2

Post by soren.a2 » Fri Aug 10, 2018 6:33 pm
I got in touch with Prusa Support.

The issue turned out to be a failure in the power-panic feature. Once I disconnected the black and white wire from the power supply the error no-longer happened. (So the printer was suspecting an imminent power failure and therefor turned of the heaters, (makes sense), but it should not later report this as a thermal-runaway).

The printer seems to be working fine with the power-panic wire disconnected.

Thanks for the suggestions.

I have the same problem. All tightened properly, Temps stable even when I shackle all wires and wire bundles. As soon its start with the bed leveling my temps starts jumping up and down.

Tomorrow I will try Soren suggestion.

Anyway Soren is this the final solution for you? What causes the actuall fault? You just leave the wires disconnected on thats it or what ich causing this problem? I have up to three power losses per week so I actually dont wont to miss this function and loose a 10 hrs print.

Re: hotend thermal runaway

The final solution was to use a replacement power supply

RE: hotend thermal runaway

Can this cause Hazardeous issue , disconnecting safety might not be safe for fire

RE: hotend thermal runaway

Power panic is a helper... not a safety feature. 

It's purpose is to try and save the last known data at the moment of a power failure in order to try and restart in the same place after a power failure.

Regards Joan

RE: hotend thermal runaway

Heu... ou se trouvent ces fils noir et blanc de la fonction panique d'alimentation???

RE: hotend thermal runaway

OK, j'ai trouvé.... PSU Power Panic...;-)

RE: hotend thermal runaway

Donc si je comprends bien, si on déconnecte le PSU Power Panic, on perd la fonction reprise d'impression après une coupure de courant !?

RE: hotend thermal runaway

Désolé, 4 réponses en 2h de temps c'est beaucoup...;-)

Bon, j'ai débranché le power panic, et j'ai encore un THERMAL RUNAWAY. Je devrais changer l'alimentation??? Voilà le message laissé sur un article qui traite du thermal runaway: https://help.prusa3d.com/article/thermal-runaway-i3-series_2131 (dernier post Dominik6280)

RE: hotend thermal runaway

• Thanks for help. I was struggling with this issue in maximum right position. Finally thanks to @joantabb I found that I have issue with hotend power cable. 13km of filament used so this element can be damaged...