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R2 reports constant, incorrect extruder temperature

Discussion in 'Troubleshooting' started by RoboticsRob, Aug 20, 2019.

  1. RoboticsRob

    RoboticsRob New Member

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    I've got an R2 here that no matter what reports a constant extruder temperature of 61 C. I've tried multiple hot ends/thermistors, multiple uptown boards, multiple downtown boards, and reseating all the connections.

    Is this the type of issue folks have seen before on this printer? Debating if I start to chase this down via the ribbon cables, or the main board first.

    Thoughts?
     
  2. Gary Boyce

    Gary Boyce Member

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    Troubleshooting the ribbon cable should be pretty easy with an ohm meter. I would start there looking for high resistance or shorts. But it sounds like a problem with the main board.

    Sent from my Pixel 3 XL using Tapatalk
     
  3. RoboticsRob

    RoboticsRob New Member

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    Thanks Gary, I actually just did that. Both ribbon cables check out alright, no shorts and no continuity breaks. I also checked the resistance from the thermistor just in case, and got ~1.0 ohms from the thermistor to the input of the uptown board.

    Guess its the main board.... unless someone else has a bit of insight into this?

    Think a firmware flash could help? I checked and its up to date.
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  5. RoboticsRob

    RoboticsRob New Member

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    Thanks Mark. I did see they offer them, but I noticed the R2 board in mine says R2 on the silk screen and that C2 board says C2, so there’s at least a difference in the screens. No idea why they’d do that unless there were other differences.

    One other thing I thought of just now is, are the thermistors in the R1/C2/R2 all the same? I can’t say for sure that these hot ends came from an R2. I figure even if these aren’t the same, the system reads 61 C even with nothing plugged in so likely not the only issue at play.
     
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    AFAIK the boards are the same (@WheresWaldo or -- more likely -- @Geof ) would know.

    The thermistors should be bog-standard 100k on both.

    The heater cores are a different story because they used 24v on the R2 and 19v on the C2... (although the 24v heater cores from the R2 will work on a C2 -- they just heat slower).
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Worst case, with a little effort you can swap the control board for something else. Either a RAMPS/ARDUINO or a Smoothy board, or whatever. Obviously less labor is involved with a direct swap :)
     
  8. Geof

    Geof Volunteer Moderator
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    I thought there were differences between the boards- can check my two units tonight but I believe it wasn’t a big deal and should work without noticeable differences. Do your homework the best you can before you buy,

    Thermistors- yea all the same but C2/R2 have different connectors than r1
     
  9. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Probably because the R2/C2 use that small board in the extruder chassis where everything lands (I show it in my C2 dual-extrusion thread). Just an interconnect board for landing the connectors and moving to a wire bundle that runs to the up-town board.
     
  10. RoboticsRob

    RoboticsRob New Member

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    Thanks. I’ll pull the mainboard and see if there’s anything visually wrong. Is this a common failure on the 2 series printers, random mainboard failure?

    Edit: the extruder does heat up, just have a ‘stuck’ thermistor reading. Realized I’d never mentioned that it does heat up
     
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That is not common, the boards are fairly solid. If the thermistor is bad THAT can be your problem :)
    It is still possible that the board is bad but I'd start with the thermistor because it is a cheap swap.
     
  12. RoboticsRob

    RoboticsRob New Member

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    I tried two different hot ends, though I don’t know for sure they both have functional thermistors. One is brand new though.
     
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Then I'd suspect the wiring or a connector.

    The R2 has some other circuit boards (the down-town and up-town boards) that "sit" between the thermistor and the main control board. If you care to look at those, my C2 thread showing the installation of the second extruder covers those. Not that getting to them is simple or easy :)

    You could have a bad connection on one of those boards (or between them)
     
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  14. KenO

    KenO New Member

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    I was having a problem with the extruder sensing the correct temperature and it turned out that the allen set screw that holds the sensor in position had come loose. So loose that it was not even toughing the sensor.
     
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  15. tkoco

    tkoco Administrator
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    Yupp! Thermal cycling can loosen set screws just like the vibration in the gantry (from printing at high speeds) can loosen the set screws of the gantry.
     
  16. RoboticsRob

    RoboticsRob New Member

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    Just wanted to update on this. It’s the main board. I put that board into a known working R2 and had the exact same temperature readout issue.
     
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  17. tkoco

    tkoco Administrator
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    Fantastic troubleshooting. Luckily you had a second R2 to test the board with.
     
  18. Lance Weston

    Lance Weston Active Member

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    In the Marlin code there is an option for reading out a fixed temp. Sounds like the firmware got glitched. A reflash should fix it. I have the last code that Robo used and if you want it will send it to you.
     
  19. RoboticsRob

    RoboticsRob New Member

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    Hey Lance,

    Sounds great, I'll take the latest code from Robo and check it out. Is it the same firmware available on the website?

    We did do a firmware flash on the printer (latest Robo3D website version) and that didn't fix it. I put a different mainboard in this particular R2 yesterday and its up and running, no trouble so far. I actually saw the extruder temperature drift +/- 2 or so degrees, seemingly random when the printer booted up, so I think it was not this fixed temperature firmware feature, though thank you for making me aware of this, I didn't know it existed.

    There is actually a hardware issue going on here though, related to the extruder temperature readout and the extruder disconnect issues people have been seeing. There was a silent PCBA revision that Robo seems to have implemented towards the end of R2 production. If you have an R2 with color coded connectors, you more than likely have this silent PCBA revision to correct the communication issue with the extruder/thermistor.

    I'm working on a couple more things and then I'll post my findings once I'm convinced that I've solved the issues with the extruder communication and implemented it on a few of our temperamental R2's.
     
  20. Lance Weston

    Lance Weston Active Member

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    This was given to me by Jason on his last day of work at Robo and is the final code.
    https://drive.google.com/open?id=1-9G3DqEJBj6Ij6g693GBRFivEWTn7be-
    Lance
     

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