Calibration issue and extrude head freezes on the side after tripping the probe

Discussion in 'Ask Team Openbeam' started by Joe Buzzitta, Sep 1, 2015.

  1. Joe Buzzitta

    Joe Buzzitta New Member

    Well I finally got the pro built - lots of redo with limited instructions.

    I turn on the Kossel Pro and the extrude head comes down and touches the plate in several places. Then it moves off the plate and trips the touch guide and freezes - on the matter android phone app it says the extruder heat is 650 degrees to 8oo degrees - but is cold. The glass plate is cold.

    We hit the Y+ Y- buttons on the app and nothing happens - my son hears a whine coming from the machine. We hit the release button and the whine stops but still no movement on the extrude head.

    We have double checked wires and even putting in several c codes we cannot get the extrude head to come down. We click on the home button - it rises to the top - does a little jig as it touches each button and then stops.

    Any suggestions?
  2. bytecounter

    bytecounter Member

    * Be sure to have the console/terminal to the printer open while debugging. It may reveal issues that the firmware reports (like thermal runaway).

    * The thermistor may need replacement/adjustment. May want to check that it is not shorting out against anything on the end effector PCB, and that it returns a resistance around 80-100k when disconnected from the PCB.

    If your hot-end is a K-Head and it's bad, the thermistor can be replaced, but it's been lathed down quite a bit so careful: http://forums.openbeamusa.com/threads/new-k-head-info-video.258/
  3. Joe Buzzitta

    Joe Buzzitta New Member

    I will try this solution - on the weekend. and then post my results.

    Hi Joe,

    The printer will refuse to move when it sees that the temperature is either too high or too low. This is what must be happening in your case. A temperature that high indicates a short in the thermistor circuit. Carefully inspect the thermistor leads and make sure that they are not contacting each other or anything else. If you have a multimeter, you can use that to trace the issue. At room temperature, the resistance across the thermistor should be somewhere in the vicinity of 100 Kohms.
  4. Joe Buzzitta

    Joe Buzzitta New Member

    I pulled the therminstate and put a meter on just the ends - the old one and the brand new one both show 15.ohms (No where near the 100k ohms) The ohm meter is set on the lowest setting which is 200
  5. grainiac

    grainiac Active Member

    That's wrong....set it to a value > 100kO. Most of the multimeters have 200kO. Then measure again!
  6. Jake Buzzitta

    Jake Buzzitta New Member

    Hi Grainiac,

    Thank you for responding, the value is set to the minimum in order to get a reading, if I set it to 2k or 20k it reads in the .1 or .01 range it is literally 15 ohms, not 15k.
  7. grainiac

    grainiac Active Member

    If you can rule out false measurement I'd say both of your resistors are fried. :(
  8. Jake Buzzitta

    Jake Buzzitta New Member

    I get a pretty accurate reading from a resistor i bought from radio shack.. ~98k so i guess we will be asking for another 2 resistors.

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