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Bed Thermal Runaway - strange fault  

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John
 John
(@john-4)
Active Member
Bed Thermal Runaway - strange fault

I was printing a quite large job today which involved the Y axis moving almost to it's extremes. Four hours into it the printer stopped with the dreaded bed thermal runaway error. Upon inspection I found that the thermistor had been 'pulled' out from its normal location such that the cable extended a mere 3cm beyond the main heater plug - nowhere near long enough to reach the centre of the bed. I found the cable had been pulled up into the controller housing. It would seem that the cable routing arrangement 'grabbed' the cable as the bed travelled in one direction but not the other until it ripped the sensor from the bed. I've done my best to re-route the cable and refit the sensor to the bed. Only time will tell if the problem is resolved. If anyone has guidance on how best to secure the sensor to the bed it would be most appreciated. I just peeled back the tape, inserted the sensor, and put the tape back. I'm nervous that the tape will not hold the sensor as well as before.
Thanks, John

Posted : 10/04/2018 9:49 pm
BillC
(@billc)
Reputable Member
Re: Bed Thermal Runaway - strange fault

I have re-used the original tape three or four times - I have had a few cable breaks. The tape has held out fine.

I am about to print cablechains in the hope that will stop the breaks.

Bill
Tagaytay City, Philippines
Founder member of Philippines Prusa Printer Owners FB Group
Sponsor Pillars of God Academy in Bacoor

Posted : 11/04/2018 1:11 pm
GertL
(@gertl)
Reputable Member
Re: Bed Thermal Runaway - strange fault

If anyone has guidance on how best to secure the sensor to the bed it would be most appreciated.

I had this happen twice. Last time i obtained some aluminum tape and secured it with that.
It have never escaped after this.

---
Gert

Posted : 11/04/2018 1:35 pm
stephen.o9
(@stephen-o9)
Active Member
Re: Bed Thermal Runaway - strange fault

What is it you are securing with tape?
I just had this happen on a very small print on a MK2S.

Best Regards Stephen Odgaard
Copenhagen DK

Posted : 14/04/2018 1:20 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Bed Thermal Runaway - strange fault

the Heatbed Thermistor, sometimes gets pulled out of place by cable movement.

if this is happening, you would be advised to review the cable management and try to identify what's catching the wire and correct that
issue first
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 : 14/04/2018 1:53 pm
GertL
(@gertl)
Reputable Member
Re: Bed Thermal Runaway - strange fault

Earlier thread about this.

https://shop.prusa3d.com/forum/-f23/thermistor-came-loose--t4387.html#p35491

---
Gert

Posted : 14/04/2018 2:16 pm
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