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Failing thermister? (Maxtemp error on hotend)  

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Failing thermister? (Maxtemp error on hotend)


I have a MK3 kit that has been printing great for 53d of "print time".  However, today I tried my first PETG print, and the printer failed with a MAXTEMP error (the hotend had gotten super hot on the first layer, despite being commanded to 240 or so).  Before this, it was exclusively PLA+ prints, so lower temps.  When just dealing with filament loading / unloading, the printer seems fine, but ask it to print, and it has now failed again (MAXTEMP error) with PLA+ and a PLA profile.  (It gets part way through the first layer, then errors.)  

Would the thermistor be a thing to replace in this case?  Does the MK3 use a standard E3D thermistor (that I have in stock at home), or is this one of the Prusa custom items that I will have to order?  (Are there any other suggested things to look at?  Is it normal for a thermistor to fail this 'fast'?)

(My older MK3 kit has been printing for almost double the time, with no issues, and it completed the PETG print fine.)  

Thanks for the help and advice,

Posted : 16/11/2019 9:46 pm
Illustrious Member
RE: Failing thermister? (Maxtemp error on hotend)

The thermistor is a standard E3D variety.  Prusa or E3D adjusts cable lengths for the MK3.  You can splice the wires to make a new thermistor fit.

Measure the present thermistor value to see if the reading makes sense. Let things cool down to room temp first. Table below:

You may want to do a PID calibration before and especially after swapping parts.  

You can also be adventurous - unload filament then heat the nozzle to 285c and watch the temperature reading. If it starts fluctuating rapidly, pretty good sign the thermistor is failing.

It is the 104NT-4-R025H42G

This post was modified 2 years ago by --
Posted : 17/11/2019 1:54 am