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Therman Runaway - MK3s  

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Bangels
(@bangels)
New Member
Therman Runaway - MK3s

Hello,

halfway during a print my printer gave the alarm "Thermal Runaway". The bed is warming up perfectly but the hotend is not doing anything. I've done several guides from the helpdesk / FAQ and have done:

  • Standard readout of Bed = 25 degrC; hotend 22 degrC
  • Preset preheat PLA or PETG: Bed warms up, nozzle does not.
  • Manual heating up (setpoint 60 degrC): No change
  • Cable wiggling and movement hotend: No change
  • Checking connections of the hotend and thermal resistor: OK
  • Voltmeter checks
  • Checking fuses:

Is there anything else I can check? (I'll try later to check directly on the pins without the cable plugged in.

Looks to me that or the connection socket from the Einsy-board towards the hotend cable is not making connection or a fault between the board itself and the socket (loose soldering)

This topic was modified 8 months ago by Bangels

- Prusa MK2 upgraded to MK2.5
- Prusa MK3s
- Ultimaker 2+

Posted : 18/02/2022 11:43 am
Bob
 Bob
(@bob-2)
Reputable Member
RE: Therman Runaway - MK3s

Have you taken this up with Prusa?  It seems you've reduced it down to a physical problem at the board.  I don't do board level repairs on my printers and I don't think many of us do.  Use the Prusa support chat feature, it's quicker than email.  They're in the best position to help with something like this.  We're going to be more helpful when it comes to getting good prints  from a properly functioning printer.

Cheers

-Bob

Prusa I3 Mk2 kit upgraded to Mk2.5s, Ender3 with many mods, Prusa Mini kit

Posted : 18/02/2022 6:55 pm
Bangels
(@bangels)
New Member
Topic starter answered:
RE: Therman Runaway - MK3s

 

Posted by: @bob-2

Have you taken this up with Prusa?  It seems you've reduced it down to a physical problem at the board.  I don't do board level repairs on my printers and I don't think many of us do.  Use the Prusa support chat feature, it's quicker than email.  They're in the best position to help with something like this.  We're going to be more helpful when it comes to getting good prints  from a properly functioning printer.

Cheers

-Bob

Thanks, will do !

- Prusa MK2 upgraded to MK2.5
- Prusa MK3s
- Ultimaker 2+

Posted : 20/02/2022 2:25 pm
Chicago Keri
(@chicago-keri)
Estimable Member
RE: Therman Runaway - MK3s

You say that both power supply pairs are at 24v below the PSU, which is good.

Did you check the other ends at the Einsy?  It should still be 24v at the Einsy terminals with the system trying to heat the hotend... with the system idle, you might get an ok reading which could change under load.

¡no entiendo Español!
Nein! Nicht Versteh!
Я немного говорю по-русски но не очень хорошо, и...
I'm not very good at English either! Maybe someday I'll find a language I'm good at?

Posted : 20/02/2022 3:55 pm
Bangels
(@bangels)
New Member
Topic starter answered:
RE: Therman Runaway - MK3s

Thanks for the suggestion !

Yes, directly under the PSU and on the board are both giving 23.8V while trying to warm up / under load. Bed warms up to the setpoint, hotend does not. The hotend heat probe increases some degrC (18 to 21 degrC) due to being close to the bed so that seems still to be working and ok.

Today I've flashed the firmware (it was already running v3.10) and still same result.

I've measured on the hotend-pins on the board directly and while requesting to warm up it remained on 0V. Contacting support via chat later this week. 

Posted by: @chicago-keri

You say that both power supply pairs are at 24v below the PSU, which is good.

Did you check the other ends at the Einsy?  It should still be 24v at the Einsy terminals with the system trying to heat the hotend... with the system idle, you might get an ok reading which could change under load.

 

- Prusa MK2 upgraded to MK2.5
- Prusa MK3s
- Ultimaker 2+

Posted : 21/02/2022 2:39 pm
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