Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error
 
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Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error  

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Tom
 Tom
(@tom-10)
New Member
Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error

Hey all, 

I have been having drama with my MINI+ this morning after 2 months of smooth operation. Besides clogged nozzles, I am getting a frequent MINTEMP error that is disrupting my prints randomly. I noticed that the heatbed temperature would randomly read -15 degrees C at times (quickly followed by the error) and then sometimes would behave normally at the desired 60 degrees C margin.

When I took the casing off the microcontroller to investigate, I noticed that it was working more reliably and the error wouldn't pop up. I quickly realized that the positioning of the 3 cables coming out of the heatbed is what's causing the errors, as if the wires have damaged weak points. Is it possible the casing is damaging the cables by crushing them? So I then leave the lid off the microcontroller hoping to finish some prototypes. However the moment the axes move to a certain position and push the three cables a certain way, I get the MINTEMP error. At this point I conclude I can no longer reliably complete prints until I get this fixed.

My question is 1) Is this a design defect of the PRUSA MINI+ and can I get replacement cables and 2) if I was to get my multimeter and soldering kit to repair, which cables should I start with? 

This topic was modified 9 months ago 4 times by Tom
Posted : 26/02/2021 5:38 pm
Pinback
(@pinback)
New Member
RE: Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error

My last two prints have given me the same error, both at random times in the print. Sounds like I have the same issue as you.

Posted : 28/02/2021 7:27 am
Tom
 Tom
(@tom-10)
New Member
Topic starter answered:
RE: Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error

@pinback

I reached out to customer support and it's a broken thermistor. I bought this unit back in December so it's under warranty and I'm getting a new part. 

This is the guide they instructed me to do for the repair: https://help.prusa3d.com/en/guide/how-to-replace-a-heatbed-thermistor-mini_142672

 

 

Posted : 01/03/2021 3:41 am
Mr.Shaky
(@mr-shaky)
Eminent Member
RE: Prusa MINI+ bad heatbed cables sensitive to position, throwing MINTEMP error

I'm on my third bed thermistor since I got my MINI in October.  I also observed the same cable flex-induced error as you; putting the printer in an enclosure will speed up the failure process.

When I got my most-recent replacement, I tested & bashed out a few modified parts to reduce flex and be more of a roll/pan motion; see https://forum.prusaprinters.org/forum/hardware-firmware-and-software-help/bed-thermistor-failing-known-issue/#post-356809

 

It's been over a month since that change and I've done around 20-25 full-bed prints; there have been no anomalies in the Octoprint temp history graph yet.

Prusa MINI w/Bondtech IFS extruder, Slice Copperhead groovemount, bed-leveling mod...
Posted : 06/03/2021 8:36 pm
Sandersann
(@sandersann)
Active Member
RE: Thanks!

Thanks for all your contributions, this thread was very helpful.

I would like to see Prusa Printers officially address this for all customers and future and existing products.

Hopefully, something is done about it.

I have only used my printer from two weeks and I got my first Mintemp bed issues linked to the thermistor's flimsy cable 

This post was modified 1 month ago by Sandersann
Posted : 24/10/2021 12:52 am
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