Incorrect idle temperature reading
 
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david.z9
(@david-z9)
New Member
Incorrect idle temperature reading

Hi,

I have noticed that the idle temperature reading on my Prusa MK2S is 34 C instead of 21-22 C (on both bed and extruder).
I don't know for sure, but I feel like it used to say 21-22 C before and this is something I noticed recently.
Has anyone experienced this? Is this an early sign of a potential problem?

The printer is working fine, but I have not explicitly measured any temperatures when it's hot enough to print.

Thanks for any help! Great printer by the way.

Posted : 14/03/2018 12:17 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Incorrect idle temperature reading

they should read close to ambient temperature... whatever that is in your area.

if they showed less than 15 centigrade it may indicate a broken wire on the thermistor

if they showed very high temperatures, that could indicate a short circuit! on the thermistor wires

keep an eye on it, but don't worry at the moment

might be prudent to order a spare of each
however if you are going to get spares, consider also the two fans, a pinda, and some cable for the heatbed... these have all failed{ at different times) on my oldest prusa... which was originally a Mk1
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 : 14/03/2018 1:07 am
Blackbird351
(@blackbird351)
Eminent Member
Re: Incorrect idle temperature reading

I have the same issue on my MKs2. It reads 9c higher than room temp. I have a MK3 sitting right next to it that reads correct.
Interestingly, if I unplug the thermistor from the board, the temp reading drops to the correct room temp.
Both thermistors read the same at room temp.
I plugged in a spare thermistor, same reading.
unplugged both from the board and both readings dropped to room temp. Used a hair dryer and warmed the board up and both readings went up.
Used dust off and dropped both temps.
I think there is an issue with the temperature sensors on the board, or the firmware (but I would think everyone would have the same problem)
The sensors are somewhere between the thermistor plugs and the square processor chip.
I realize that the temps will vary a little, but 9c seems like too much.

Posted : 14/03/2018 8:07 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Incorrect idle temperature reading

not all Mk3's read high at idle[attachment=0]20180314_212057[1].jpg[/attachment]

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 : 14/03/2018 10:23 pm
Blackbird351
(@blackbird351)
Eminent Member
Re: Incorrect idle temperature reading

I agree. My MK3 reads perfect according to my IR camera.

Posted : 16/03/2018 9:01 pm
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