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Hotend temperature jumping.  

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cwbullet
(@cwbullet)
Member
Hotend temperature jumping.

I am getting a weird result from my mini.  I am printing in PETG and it jumps from 225 and 255.  I thought it was a loose wire to the thermistor, but it happens even when the printer is not moving.  If I warm it to PETG settings, it will go to 170 and jump between 170 and 185.  I will pause a few seconds at each number.  

The odd thing is if I set a temp on the settings, it stays on that number with 1-2 degrees.  

Any ideas where I should start?  

--------------------
Chuck H
3D Printer Review Blog

Posted : 23/01/2021 2:15 pm
Turro75
(@turro75)
Estimable Member
RE: Hotend temperature jumping.

Since You have many mini, try to swap the thermistor and see if the issue stay or move. I bet thermistor wiring damaged. 

be aware that clone should work on thermistor type 1 while original uses type 5, this roughly weight 20c gap. 

Posted : 23/01/2021 2:22 pm
cwbullet
(@cwbullet)
Member
Topic starter answered:
RE: Hotend temperature jumping.

@turro75

What is the difference between Type 1 and 5?  Do you have photos?

--------------------
Chuck H
3D Printer Review Blog

Posted : 23/01/2021 2:27 pm
cwbullet
(@cwbullet)
Member
Topic starter answered:
RE: Hotend temperature jumping.

Is this what you are referring to?  

https://3dprintboard.com/showthread.php?10406-Comparison-of-Type-1-thermistor-and-E3D-thermocouple-temperature-measurements

--------------------
Chuck H
3D Printer Review Blog

Posted : 23/01/2021 2:29 pm
Turro75
(@turro75)
Estimable Member
RE: Hotend temperature jumping.

https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/master/lib/Marlin/Marlin/src/module/thermistor/thermistor_1.h

https://github.com/prusa3d/Prusa-Firmware-Buddy/blob/master/lib/Marlin/Marlin/src/module/thermistor/thermistor_5.h

You can see the table used in the firmware that report the analog value read by microcontroller and the temperature associated to that value.

Unfortunately on china grade thermistor You can hardly ever find the real datasheet so it is difficult to say which type is what looking at picture. the best option is comparing the setpoint temp to a proven thermometer and see who is lying.

Anyway for Your case I said this to You just to be aware that swapping thermistors among clone and genuine mini would lead in a 20c gap. 

 

 

Posted : 23/01/2021 2:41 pm
cwbullet
(@cwbullet)
Member
Topic starter answered:
RE: Hotend temperature jumping.

@turro75

ok.  Thanks.  It is original Mini and Thermistor.  I will see what I have.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 23/01/2021 2:45 pm
cwbullet
(@cwbullet)
Member
Topic starter answered:
RE: Hotend temperature jumping.

This is really odd.  I don't think it is the thermistor.  I thought it might be Octoprint.  I was getting a lost connection error, so I removed it and printed a print from the thumb drive.  The printer reset 1/4 the way through the print printing from the thumb drive.  I am wondering if I have a bad power supply.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 24/01/2021 4:34 am
cwbullet
(@cwbullet)
Member
Topic starter answered:
RE: Hotend temperature jumping.

Update: I swapped out power supplies and it seems to be working without issue.  Time will tell.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 25/01/2021 3:13 am
T-bone
(@t-bone)
New Member
RE: Hotend temperature jumping.

I realise this is an old post, but I am having the same issue with my mk3s+. Prusa has rma'd the thermistor and motherboard but it did not resolve the issue. Did this permanently solve your problem?

Posted : 18/12/2022 6:41 am
DeviousWay
(@deviousway)
New Member
RE: Hotend temperature jumping.

I'm also interested in a follow-up, I'm having a similar issues with my Mini+ that I purchased over Black Friday.  

The runaway seems to happen anywhere from 5 minute to 40 minutes.    I've gone through all the trouble-shooting this page has provided except the resistance check.  One time I managed to pause the print when I noticed the temp dropping, and I watched as the numbers flickered all over the place.  While paused, the numbers go from 190/215 to 230/215 to 200/0.  I let it rest until the numbers stabilized at the 215/215 temp.  I was curious to see if the numbers would flux again, so I resumed printing.  No issues for the 20 minutes remaining print.  But this seems like a constant issue at that 30-40 minute mark, as I tend to have about 80% failure rate right now.

Note: I got the Prusa because I purchased a friend's older Ender3 (he switched to Resin) and got sick of endless fiddling.  Now I'm fiddling on this... I'm not really happy right now.

Posted : 18/12/2022 8:34 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Hotend temperature jumping.

Have you tried Prusa Chat?

It's available on the bottom tight hand corner of  Prusa eshop pages (takes 3-5 seconds to materialise, as long as you don't have an aggressive Ad blocker!

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

Posted : 18/12/2022 8:53 pm
T-bone
(@t-bone)
New Member
RE: Hotend temperature jumping.

Hi,

 

yes I have. That is how I got the thermistor and motherboard Rma’d 

Posted : 18/12/2022 8:57 pm
T-bone
(@t-bone)
New Member
RE: Hotend temperature jumping.

Lol. This is why I bought my prusa a couple months ago. I got rid of my ender 3 to avoid constant fiddling. Now I've swapped a motherboard and a thermistor. I am printing right now to measure the psu and see what voltage it shows when the issue is occuring.

Posted : 19/12/2022 4:07 am
Jeralanight
(@jeralanight)
Member
RE: Hotend temperature jumping.

Has anyone found a solution to this problem? I've had this issue multiple times and the only way I've managed to get it to work was to update the software on my mini. Now I've had the same problem today and I am at a loss of what to do.

Posted : 07/10/2023 2:33 pm
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