[Solved] Big Temperature difference between Sensors  

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surtic86
(@surtic86)
Active Member

Hi there,

I have a Problem with my new Prusa i3 MK3s. The Temperature Sensors have a big difference from Ambient to Bed and Nozzle.

What can be here wrong? I checked the Nozzle Connection and looks fine to me. Is there eventually a Calibration Issue or is the Thermistor crap?

I can print fine and the Result looks really good. But the Nozzle Temperature drops sometimes less then 15°C and so i get the MINTEMP Error.

Posted : 06/09/2019 1:45 pm
Sembazuru
(@sembazuru)
Reputable Member

The "Ambient" temperature is probably poorly labeled. It is actually a sensor on the Einsy board so will likely show an elevated temperature with it surrounded by heat producing parts, crammed into that small box with cables stuffed in impeding good air flow. (IMHO the Einsy enclosure is too small for the number of wires needed. the board should probably be redesigned a little larger to allow connectors only along the edges to help with cable management...)

But I do see your nozzle temperature as odd. With the printer off and fully cooled to ambient temperatures, I would expect the nozzle and PINDA temperatures to be similar since they are so close together (only an inch or two), and both should be near the bed temperature unless you have weird drafts creating an unusual thermocline in the small space between the bed and extruder assembly (up to only 1ft).

Unfortunately, I can only confirm your observation. I'm not sure what the resolution would be short of replacing the heater block thermistor.

Posted : 06/09/2019 2:50 pm
surtic86 liked
surtic86
(@surtic86)
Active Member
Posted by: Sembazuru

The "Ambient" temperature is probably poorly labeled. It is actually a sensor on the Einsy board so will likely show an elevated temperature with it surrounded by heat producing parts, crammed into that small box with cables stuffed in impeding good air flow. (IMHO the Einsy enclosure is too small for the number of wires needed. the board should probably be redesigned a little larger to allow connectors only along the edges to help with cable management...)

Yes i think the Ambient is normal to be a bit higher because off the "no" Air in the Wire Casing. And also eventually the Bord generates some heat.

Posted by: Sembazuru

But I do see your nozzle temperature as odd. With the printer off and fully cooled to ambient temperatures, I would expect the nozzle and PINDA temperatures to be similar since they are so close together (only an inch or two), and both should be near the bed temperature unless you have weird drafts creating an unusual thermocline in the small space between the bed and extruder assembly (up to only 1ft).

Hehe 🙂 no i don't have such a strange thermocline 😉 also my printer is in a IKEA Incasing so it should be well protected. The Room Temperture is around 20-23°C (Thermostat on the top of the Incasing. 

Posted by: Sembazuru

Unfortunately, I can only confirm your observation. I'm not sure what the resolution would be short of replacing the heater block thermistor.

Okey... i will write to the Support and hope to get there a Answer / new Thermistor for the Nozzle. Because my Printer is less than a Week old.

Posted : 06/09/2019 3:03 pm
Sembazuru
(@sembazuru)
Reputable Member

I haven't used the support email, but the scuttlebutt is they are slow at responding to email. If you go to the Prusa store and login, there should be a chat button to get rapid support. (Oops, I just checked to get the URL, and I wasn't logged into the store but still got the "Chat now..." button. Maybe being logged in first isn't necessary to get the chat button. I'd still login anyway with the hope that will help the support person access your account to see that your printer is only a week old...)

Posted : 06/09/2019 3:08 pm
surtic86 liked
surtic86
(@surtic86)
Active Member

After some E-Mails with the Support they send me a new Thermistor. Hope it will fix my Problem 🙂 else i have another problem.

Posted : 10/09/2019 2:37 pm
Robert-mm200
(@robert-rmm200)
Reputable Member

Let me put a plug in for Chat support. They can step you through debugging, which you really can't do well through EMail.

Posted : 10/09/2019 7:01 pm
surtic86
(@surtic86)
Active Member

So i got the new Thermostat. I also got e Multimeter from my Friend. The old Thermostat was showing me 140kΩ and the new one 104kΩ by a Room Temperature from around 22°C. 

I will check on the Weekend when i have time to Build it into my Printer how it looks. But so far i can say the Thermostat was damaged... wrong Calibrated or so.

Posted : 12/09/2019 10:04 am
joan.t
(@joantabb)
Veteran Member Moderator

thermistor should show 100K at 25 Celcius... so 104K at 22 Celcius is reasonable

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 : 12/09/2019 1:46 pm
surtic86
(@surtic86)
Active Member

New Thermistor 🙂 now it looks perfect.

 

Posted : 13/09/2019 2:44 pm
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