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Bed Thermistor runaway  

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CellarDoor
(@cellardoor)
Eminent Member
Bed Thermistor runaway

I just got a Bed Thermistor runaway error. Restarting my 2.5 and doing a selftest I get a “Heater/Thermistor not connected” error. The cable looks fine (not bent, not broken anywhere), the board and pin thereon look fine, the Thermistor is properly connected to the downside of the bed.

It seems that also the heating does not work. Setting both hotend and bed to a certain temperature (e.w. 230/85) heats the hotend, but the bed stays at room temperature.

I checked a few search results, where I found these, but i sadly don't have a multimeter available. What can I do now and check?

Veröffentlicht : 05/01/2019 11:25 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Bed Thermistor runaway

what temperarure do the bed and extruder thermistors indicate when at room temperature?

if the extruder temperature is correct and the bed well below temperature, then it is likely the bed thermistor is faulty

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Veröffentlicht : 05/01/2019 12:42 pm
CellarDoor
(@cellardoor)
Eminent Member
Themenstarter answered:
Re: Bed Thermistor runaway

Both temperatures are ok (27 degrees); fuses are ok. Still looking for further issues.

Veröffentlicht : 05/01/2019 12:59 pm
CellarDoor
(@cellardoor)
Eminent Member
Themenstarter answered:
Re: Bed Thermistor runaway

Today I found some time to check again. I carefully unplugged and replugged all cables going to the heatbed, followed the idea of unplugging the PINDA probe on first boot ( see https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/heater-thermistor-not-connected--t18904.html#p116070 ) and instead of a complete selftest first just tried to set the temperature of the heatbed.

It heated!

So I powered down again, replugged the PINDA (though not sure whether that really had an effect, but if somebody sees this - maybe it does) and did a selftest - seems to be fine again.

I am not completely sure what caused this, maybe one of the heating current cables came a little loose, but a first small print already finished positively.

Thanks joan.t for the tips.

Veröffentlicht : 07/01/2019 10:01 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Bed Thermistor runaway

🙂
best wishes!

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Veröffentlicht : 08/01/2019 1:58 am
CellarDoor
(@cellardoor)
Eminent Member
Themenstarter answered:
Re: Bed Thermistor runaway

...sadly that only worked for about 4 prints. So one of my cables might have a damage I fear.

Veröffentlicht : 09/01/2019 8:05 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Bed Thermistor runaway

🙁 Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Veröffentlicht : 09/01/2019 11:21 pm
CellarDoor
(@cellardoor)
Eminent Member
Themenstarter answered:
Re: Bed Thermistor runaway

Today I found some time again.

* all cables are ok, I checked them
* I replaced the heatbed with a replacement one I already had here
* I also checked all the cables of that one
* The selftest fails because the temperature stays at room temperature and the heatbed does not heat
* fuses still ok
* the “trick” from before to once start without PINDA attached did also not work

I am out of ideas (and I just got it back about 1.5 months back from prusa repair, so somehow I am really not getting started with my 2.5).

Veröffentlicht : 12/01/2019 3:15 pm
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