Replace thermistor with PT1000 - temp readings reversed
 
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etothex23
(@etothex23)
Active Member
Replace thermistor with PT1000 - temp readings reversed

I had an original prusa thermistor for the hot end and replaced it once with a slice 300 and now again replacing it with a PT1000. I have checked the resistance which is reading 1.1 k ohms and bed reads 84-85k ohms. This seems in range. the connection also reads that it is a complete circuit. When I start the printer the thermistor reads 158 c and then if I heat it with a heat gun the temp drops. The bed temp if I heat it acts as expected the heat goes from ambient to rising.

I am going to try flashing the firmware for the PT1000 then try again.

I have no idea why the temp would read in reverse like that so I guess maybe the firmware could be an issue.

Any thoughts?

Posted : 27/07/2023 11:23 am
René
(@rene-3)
Reputable Member
RE: Replace thermistor with PT1000 - temp readings reversed

PTC means positive temperature coefficient.

As the temperature increases, the resistance increases.

NTC means negative temperature coefficient.

As the temperature increases, the resistance decreases.

This therefore explains the 'inverted temperature' reading

The printer works with an NTC sensor.

Posted : 27/07/2023 11:46 am
jvasileff liked
etothex23
(@etothex23)
Active Member
Topic starter answered:
RE: Replace thermistor with PT1000 - temp readings reversed

it was the firmware. I didnt even think about it

Posted : 27/07/2023 12:51 pm
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