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Unresolved TEMP FALL ERROR

Discussion in 'Troubleshooting' started by James Slaughter, Jun 17, 2016.

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  1. James Slaughter

    James Slaughter New Member

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    So I just got a ROBO R1+ I got it used and haven't gotten a single print off of it. I begin to print and then run into the temp fall error. I've gone and looked at other forum posts. checked all the connections , I used a mulimeter to check the continuity and everything checked out fine. So I believe it's a bad thermistor. I did check the resistance of the thermistor and I got 7k ohms. Not sure what it is supposed to be though. I just have 2 questions.
    1.Does that sound correct or is there something I'm missing
    2.if it is the thermoster is there a specific type I need. Or a link to buy them.
     
    #1 James Slaughter, Jun 17, 2016
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    7k is way low. You would never get an actual temperature reading with that. They are 100k thermistors.

    If it is sometimes reading correctly then the 7k is just a bogus reading.

    As you said the temperature fell too much error is always the thermistor, either it is loose and reads incorrectly once the head starts moving or it is cracked and again-- movement will make it read incorrect.

    As for buying them this will work :

    https://www.amazon.com/RioRand-10-100Kohm-NTC-Thermistors/dp/B00GD4

    BUT ... (don't click BUY just yet).

    The R1+ has an odd mount that I am not sure how to repair so you are going to need to go back to Robo to get the correct replacement thermistor. Most hotends just have a small hole for the thermistor and a set screw to latch the wires and hold it in place. Sadly the R1+ hotend it is not just a thermistor, but in a can mounted thermistor that mounts into the hotend with a set screw.

    You might consider upgrading/replacing the hotend for one that uses standard parts, but that is a bit more work. It is worth it, both of mine use E3D, but I can't make that call for you. You might get this fixed and be problem free for years.
     
    #2 mark tomlinson, Jun 18, 2016
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  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If you DO go with a new hotend I'd strongly suggest use of the MetalStud thermistor as they are largely indestructible.
     
    #3 mark tomlinson, Jun 18, 2016
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  4. James Slaughter

    James Slaughter New Member

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    Hmm ok thank you if I'll probably call robo on Monday and see if I can get a replacement thermoster and then see if that's fixes it. Side note I've seen on Amazon the E3D print head made by e3d for 80$ and then the same print head or a copy of it for 20$. Now I know usually the general concensus is you get what you pay for but, is there a large difference between the two or not?
     
    #4 James Slaughter, Jun 19, 2016
  5. Geof

    Geof Volunteer Moderator
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    Trust me... only buy the true e3d.

    Www.printedsolid.com

    I use Matt at PrintedSolid for all my e3d needs. Get the stud thermistor while your at it and you wont have to do firmware changes :)
     
    #5 Geof, Jun 19, 2016
  6. Harison Kelmer

    Harison Kelmer New Member

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    Thanks. I think the thermistor is bad. I just received the new one today and am getting ready to install it. I had two quick questions though:
    1 - I tried printing one last time with the old thermistor. Same temp fall error. I took resistance readings of the thermistor both before and after the print. Before the print, when it was cold, it was reading 92 kohms. Which I believe should be about correct. Right after it errored out, however, I checked it again and it was just above 2 kohms. That seems like one heck of a drop. Is that normal? Would just like to know before I swap in the new one.
    2 - Are there instructions on how to swap out the thermistor on this printer? All of the how to's I have seen show changing out the thermistor from an aftermarket (E3D) head, not the Robo one.

    Thanks!
     
    #6 Harison Kelmer, Jun 22, 2016
  7. Geof

    Geof Volunteer Moderator
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    If you look at the bottom of your heater block by the nozzle youll see a set screw dorectly under the thermistor. Unplug the thermistor loosen that set screw. Pull the old thermistor out carefully push the new one in...dont break the fragile wires. Tighten the set screw plug it in and your good to go !
     
    #7 Geof, Jun 22, 2016
  8. Harison Kelmer

    Harison Kelmer New Member

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    Do I have to remove the print head to install this? I ask because the only set screw I see at all is above the thermistor (as I am looking at the 3D printer) and its at the bottom of the heat sink I believe it is. I see no other set screws.
     
    #8 Harison Kelmer, Jun 22, 2016
  9. Geof

    Geof Volunteer Moderator
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    Hang on a sec and ill take a picture and upload for you.
     
    #9 Geof, Jun 22, 2016
  10. Harison Kelmer

    Harison Kelmer New Member

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    figured it out. Thanks!
     
    #10 Harison Kelmer, Jun 22, 2016
  11. Harison Kelmer

    Harison Kelmer New Member

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    Now to see if it fixed the problem!
     
    #11 Harison Kelmer, Jun 22, 2016
  12. Geof

    Geof Volunteer Moderator
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    Ah gotya let us know how you get along
     
    #12 Geof, Jun 22, 2016
  13. Harison Kelmer

    Harison Kelmer New Member

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    Dang it! No luck. Same symptoms! This is with a new thermistor from Robo. I called their tech support and they said it could be an issue with the wiring from the thermistor to the Arduino. While that is certainly possible, I metered out connectivity three times between both ends of those wires. Any thoughts on what next to check? Thanks!
     
    #13 Harison Kelmer, Jun 22, 2016
  14. Geof

    Geof Volunteer Moderator
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    Can you heat the extruder with the cooling fans at 50% without it erroring out ?
     
    #14 Geof, Jun 22, 2016
  15. Geof

    Geof Volunteer Moderator
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    Its possible you have a very weak heater and the cooling fan is over running it
     
    #15 Geof, Jun 22, 2016
    Last edited: Jun 22, 2016
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  16. Harison Kelmer

    Harison Kelmer New Member

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    I have been running it with the fan off to make sure it couldn't overrun the heater...

    So I don't think that could be the problem. Also, I can sit and watch the temps for a while and they don't move below 235 by much. That's what I have it set at for ABS. Should I have it set at something different?
     
    #16 Harison Kelmer, Jun 22, 2016
  17. Geof

    Geof Volunteer Moderator
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    Well min temp is either


    1 a bad thermistor

    2. a bad heater

    3. bad ramps board or the wiring to it. Double check the thermistor is seated firmly
     
    #17 Geof, Jun 22, 2016
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  18. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    With the heater on and the machine NOT printing -- wiggle all of the wiring harness. Watch the temperature graph and see if tit spikes down. Start at the furthest point away from the extruder and work your way back jiggling the harness.
     
    #18 mark tomlinson, Jun 22, 2016
  19. Harison Kelmer

    Harison Kelmer New Member

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    The thermistor was replaced today and is seated firmly inside the print head. The set screw is tightened nice and tight.

    I contacted Robo and they are sending me a new wire from the thermistor to the aruinous board. I will heat up and wiggle the wires as recommended above and see if there is any change in the Temps.

    Any way to check to see if it's a bad heater?
     
    #19 Harison Kelmer, Jun 22, 2016
  20. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Yep, bad wiring looks just like a bad thermistor :)

    If it gets hot it is probably not the heater core. Those usually work right or not at all. I guess it could get weak... I prefer the 40w generic cores you can get from Amazon. Better than the 30w Hexagon or 25w E3D ones...
     
    #20 mark tomlinson, Jun 22, 2016
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