Is it ok to repair a damaged heatbed thermistor cable?  

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vpx
 vpx
(@vpx)
New Member

Hello, 
I have a damaged heatbed thermistor. The cable has been damaged by bending multiple times against the frame while printing.
As the thermistor itself is not damaged (only the cable), would it be safe to slice, solder and heat shrink the cable?
Would it still read the same values?

Thanks a lot.

Posted : 21/09/2020 2:53 pm
jsw
 jsw
(@jsw)
Noble Member

If the cable has been mechanically stressed, as in repeatedly, I would replace it rather than repair.  However, if you feel confident in your soldering and cable repair skills, and just want a quick fix, it should be possible.  The resistance of the cable should be very low compared to that of the thermistor at any temperature, so the resistance of it is not significant.

Now if the resistance of the cable reads anything other than a solid zero ohms, it should be replaced.

Posted : 21/09/2020 4:48 pm
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karl-herbert
(@karl-herbert)
Illustrious Member
Posted by: @vpxavier

Hello, 
I have a damaged heatbed thermistor. The cable has been damaged by bending multiple times against the frame while printing.
As the thermistor itself is not damaged (only the cable), would it be safe to slice, solder and heat shrink the cable?
Would it still read the same values?

Thanks a lot.

After the heatbed thermistor wires on my MK3 were defective twice, I replaced these and also the 24V wires with heat-resistant, flexible silicone material like this one or similar: https://www.rrkabel.com/silicon-cable/silicon-cable-sid

I haven't had any problems with this for over 2 years. In the meantime all moved wires have been replaced by this material.

 

 

This post was modified 5 months ago by karl-herbert
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 21/09/2020 5:25 pm
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cwbullet
(@cwbullet)
Illustrious Member

@karl-herbert

I did this also.  I used 14AWG wire I a bought from Amazon.  You can probably buy it anywhere.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 21/09/2020 9:31 pm
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Swiss_Cheese
(@swiss_cheese)
Reputable Member

yes, if you know how to repair the wire properly, if not then just order a new one, replace it, and learn on something else. the system is in place to control the temperature of the bed, it is also part of a built in safety to avert a fire hazard.

If you order New don't just get one order two or three. they do wear.

This post was modified 5 months ago by Swiss_Cheese
Posted : 22/09/2020 1:44 am
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Swiss_Cheese
(@swiss_cheese)
Reputable Member

I tried to edit the last post but ran out of time, I wanted to mention that once you pull the Kapton, if you work on the wires the tape is pretty much done for, and you will need new tape, keep that in mind, the replacements from prusa come with a piece to replace it. I have new thermistor kits on hand for quick repairs, since for me time is of the essence, however when I have time I do repairs on the wires for reuse as long as the thermistor is still good.

Posted : 22/09/2020 1:57 am
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vpx
 vpx
(@vpx)
New Member

Thanks a lot. I replaced it by a new one already but wanted to know if it was possible as the thermostor itself is not broken.

Posted : 22/09/2020 7:41 am
JoanTabb
(@joantabb)
Moderator

@vpxavier

Yes you can repair the wires on the thermistor, Flexible Silicone insulated wire is the best bet. 
22AWG is adequate because the thermistor is a low power sensor, 

If the Heatbed wires fail, 16 AWG Wire is adequate, 14AWG is a heavy duty alternative. 

the Thermistor wires are not polarity conscious, 
the Headbed power wires ARE polarity conscious, the heatbed doesn't care but the LED will not light if reversed!

for the thermistor  cut the wire inside the Einsy Rambo case, and just under the heatbed and I use heatshrink tubing, with solder to graft new wires into the wiring loom.  this way the taps over the thermistors don't need attention, and the joints are not strained by flexing. 

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 : 22/09/2020 6:14 pm
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