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ritchrock
(@ritchrock)
Eminent Member
Prusa MK3 Temperature Problem

Hi all,
After working well for quite some time, my MK3 has started giving me problems. Not exactly sure what to make of this to be honest. Here is what happened with my latest print:

1. Things started normal.
2. I came to check on the print and noticed in Octoprint that the temperature had been overshooting quite dramatically at times. Here is what it looked like:

3. Since things were not normal I stayed to watch the print. Suddenly it stops and it started smelling like burning plastic. Then, the Prusa buzzer starts sounding very loudly and the screen changed to this:


 
4. With no temperature readout I had no idea if the machine was going into thermal runaway, as there was some smoke and it started smelling terrible. So, I pulled the plug. I then plugged it back in so the fans could turn on and it cooled down normally from there. I did have to physically move the z-axis up to get the nozzle off the plastic it had embedded itself on.

Now I am here wondering what I should do next.

Posted : 22/07/2020 2:31 am
ritchrock
(@ritchrock)
Eminent Member
Topic starter answered:
RE: Prusa MK3 Temperature Problem

Just noticed that Octoprint threw up this error:

Posted : 22/07/2020 2:35 am
bobstro
(@bobstro)
Illustrious Member
RE: Prusa MK3 Temperature Problem

Did you by any chance update your firmware to 3.9 recently?

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 22/07/2020 5:49 am
ritchrock
(@ritchrock)
Eminent Member
Topic starter answered:
RE: Prusa MK3 Temperature Problem

I am on firmware 3.8.1-2869. Should I update to the latest?

Posted : 22/07/2020 3:03 pm
bobstro
(@bobstro)
Illustrious Member
RE: Prusa MK3 Temperature Problem
Posted by: @ritchrock

I am on firmware 3.8.1-2869. Should I update to the latest?

Not necessarily. 3.8.1 has a bug that can cause layer shifts when the filament sensor is enabled. However, 3.9 has some bugs that are causing shutdowns and other problems that sound (remotely) like your problem. Just wanted to be sure. If you're using Octoprint, try the same print directly from SD card. This may be more of a hardware issue.

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Posted : 22/07/2020 4:34 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Prusa MK3 Temperature Problem
Posted by: @ritchrock

Hi all,
After working well for quite some time, my MK3 has started giving me problems. Not exactly sure what to make of this to be honest. Here is what happened with my latest print:

1. Things started normal.
2. I came to check on the print and noticed in Octoprint that the temperature had been overshooting quite dramatically at times. Here is what it looked like:

3. Since things were not normal I stayed to watch the print. Suddenly it stops and it started smelling like burning plastic. Then, the Prusa buzzer starts sounding very loudly and the screen changed to this:


 
4. With no temperature readout I had no idea if the machine was going into thermal runaway, as there was some smoke and it started smelling terrible. So, I pulled the plug. I then plugged it back in so the fans could turn on and it cooled down normally from there. I did have to physically move the z-axis up to get the nozzle off the plastic it had embedded itself on.

Now I am here wondering what I should do next.

The hieroglyphics on the LCD are annoying, because it is a known M112 display bug in 3.8.1 and was already corrected in 3.9.0 (I have corrected this myself in 3.8.1).
With the fluctuating temperatures in the octoprint display, a loose thermistor contact could be involved, which can cause very strong temperature fluctuations. I would check this first. I have had this problem before and with the installation of a new thermistor cable the problem was solved. Otherwise my printer runs largely error-free with the 3.8.1. I will not install the 3.9.0 and rather test a subsequent version.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 22/07/2020 5:04 pm
ritchrock
(@ritchrock)
Eminent Member
Topic starter answered:
RE: Prusa MK3 Temperature Problem

@karl-herbert

Thermistor was my thought also. I should have a spare, so I'll pop a new one in and see how it goes. I haven't upgraded past 3.8.1 since it's been stable.

Posted : 22/07/2020 5:07 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Prusa MK3 Temperature Problem

@ritchrock

In my case the thermistor was ok, but one thermistor wire in the movable cable bundle in the area of the Einsy housing had a loose contact/break. Activate the nozzle heater and move the cable bundle. If the temperature fluctuates, I'd change both thermistor wires.

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 22/07/2020 5:25 pm
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