intcorrect extruder tempreported

[Jabl]

I have a Prusa I3 Pro B printer.

If I measure the temperature of the hotend with a separate thermometer.
Actually a multimeter with a temp sensor.
The external measurement consistently report a 30 - 40 degrees higher temp
than what the Marlin firmware reports.

What temperature sensor type is the correct one for a Mk8 extruder/hotend ?
I can't find any documentation on what sensor is supplied with the Mk8 extruder...

Everything indicates that the extruder is working at a much higher temp than it should.
Including the extruder "base" bending due to high temperature.

I have tried several 100K sensors but I can't see any difference ?

Please let me know what the correct setting should be.
Regards

[zhangxueyou]

So the only problem is that the actual temperature is higher than the temperature reading from LCD?

[Jabl]

Yes.
But Repetier host also "see's" the incorrect temperature and Marlin acts according to it.
That is, If I set a extruder temp of 240 C, the actual temp being used is around 260-275 C.

The odd thing is that the heated bed reports the correct temp....

[zhangxueyou]

You can change it in "thermistortable.h".

[Jabl]

My problem is that I don't know what type of thermistor is actually in the hotend, so I dont know what the data are to enter ?
If you could provide the identity / type of thermistor mounted, I can easily enter the values.

[zhangxueyou]

Is this information in "Configuration.h" useful for you?
"
1 is 100k thermistor - best choice for EPCOS 100k (4.7k pullup)
"

[Jabl]

Thank you
That exactly what I needed to know.