Thermal runaway and now preheating won‘t work
Hello, since two days I have a really odd behavior of my MK3, which leaves the printer useless at the Moment.
The last print I failed with a thermal runaway error. Restarting the failed print did not work.
I did some troubleshooting.
- reconnect all heating and Thermistor connectors on system board as well as power supply.
- re-inserted the fuses on system board.
- removed the spiral wrap and nylon filament from heatbed wires to system board.
- Factory reset with recalibration. The self-test worked after a few tries (and checking connectors on System board). All other calibration steps worked well except the first layer calibration, since neither the Extruder nor the heatbed is heated to necessary temperatures.
- re-installing latest RC Firmware.
All steps did not solve the issue and I have no clue what may be the Root cause for this issue.
So far I only used PLA and PET and did not print fancy stuff (just a few from the Demo files and a simple selfdesigned nameplate.
The printer is used at a room temperature around 22° C and ran for maybe 100 hours.
I noticed when preheating a red LED lights up when heating up the bed and extruder. Randomly this LED turns off and heating up both stalls and the Extruder and bed cools down again (the printer worked well for four weeks, the LED usually blinks, when keeping the heatbed at selected temperature). When I reset the printer and start preheating again, Thus won't work most of the time, I have to turn off the printer, reconnect the Thermistors and heaters, power on the printer again and do preheat. And then the preheating stops again. The heatbed usually stalls at 50° C max. And the Extruder sometimes stalls at 210° C, but mostly below 200° C.
I also contacted support already and wait for some reply. At the moment it seems it could be everything which causes this failure. Since heating up of the Extruder and bed makes issues, I guess the RAMBo board has some malfunction, but this is a mere guess. What‘s really annoying I had configured the printer a day befor to near perfection regarding Live Z adjustment and heating temperature. But Okay, that‘s life.
Any ideas what maybe root cause for this?
Thanks in advance,
Klaus
Re: Thermal runaway and now preheating won‘t work
Just got something similar with my mk2s. It has about 100h of print-time, and has worked great, but now i got thermal runaway and finally "bed preheat error". No word from support yet :-/
The led is not blinking. 0 volt on the bed and 0V on the rambo. But I measure 12V on the rambo when I disconnect the bed-cable.
Re: Thermal runaway and now preheating won‘t work
First figure out if it's the nozzle, bed, or both. Go to Settings > Temperature > Nozzle, and let it heat up to print temps for a while, make sure the temp is stable. If the nozzle is fine then try the bed next.
If it's the bed, check that the thermistor didn't work itself loose under the tape. It may be just loosely hanging there.
If the problem only happens while printing, it is likely one of the thermistors has an intermittent short when the cable is bent at a certain angle, this would require replacing the thermistor.
Re: Thermal runaway and now preheating won‘t work
Thanks jettoblack, I did exactly that and it seems it's the thermistor under the bed. I got response yesterday from support with exactly these steps. Waiting now after these tests (heating up Nozzle and bed separately, wiggling the wires to the Einsy board and/or moving x- respectively y-axis)
The Nozzle seems to be fine, with heating up up to 250° C. If I heat up the bed, after Some time heating stöpselnd won't recover. And then, the nozzle won't heat up again also.
I also noticed, after a being powered of a few hours heating up the Nozzle or the bed works again. Hopefully, I wil check out the thermistor tomorrow. Maybe I get also some more information from support. Seems to be busy times for that guys. I can't blame them, I know tech support can be really exhausting.
OddRune.d, this is exactlythe same issue I encounter. I will report when I checked the heatbed thermistor.