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Unresolved Heated bed issue

Discussion in 'Troubleshooting' started by John H, Feb 1, 2016.

  1. John H

    John H Member

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    So I have a printer that I have not used in 9 months, I've had so many problems , that i shouldn't have had.. That I just gave up using this printer, first day using the printer I had to glue parts together as per instructed . about a month later my heat bed shit the bucket ,Wires melted together and had to fix that , about a month after that the bed was out again. Was told to trouble shoot it , by changing the thermistor, I did, and it still dose not heat, I traced the wires back , and i see no breaks in the wire.
    Now Im back at it again and would love to get the heated bed to work .
    For the amount of time I used this machine It should be brand new still. I havent even finished the small roll of PLA. and made about 10 prints with ABS before the heat bed went bad.
    So what are my next steps, I replaced the Thermistor on the heat bed, and inspected the wire for breaks. Thats where Im at now .. Thanks again for your help.
     
    #1 John H, Feb 1, 2016
  2. John H

    John H Member

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    Not Solved !!!
     
    #2 John H, Feb 1, 2016
  3. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, can you be a little more clear on the symptoms?
    From what you have told us all we do know is that :

    1) the heated bed is misbehaving some way
    2) it probably isn't the thermistor.

    So, how is the bed not working? What is the thermistor reading before heating, during heating?
    What errors (if any) are in the communications log?
    Which Robo3D printer specifically is this?
     
    #3 mark tomlinson, Feb 1, 2016
  4. John H

    John H Member

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    Thanks Mark ..

    Ok the bed reads zero.
    I have had no errors come up.
    This is the R1 with (autolevel)
    I had contacted Jerry many months ago, Was told to change the thermistor , I did ,and that didn't work , since then I gave up on this printer , As far as readings go, I can take readings but of what ? and where ? There's so much information all over this site, but nothing clearly states trouble shooting procedures. I have no idea what Ramps are, what they look like where there are. Perhaps a sticky with an Exploded view showing each part and it's name. ( just a thought ) . So yeah what do I do?
    Thanks again.. John
     
    #4 John H, Feb 1, 2016
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    If changing the thermistor did not solve it (I assume it read zero before you replaced it and still reads zero after replacing it).
    Then it is likely a bad/loose wire from the RAMPS. Make sure the thermistor is landed correctly on the RAMPS board.

    The temperature readings in the software was all I wanted.
     
    #5 mark tomlinson, Feb 1, 2016
  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    This is posted in a number of threads (some sticky) but I always repost it anyway: Here are two views of the ramps and that is the board the thermistor is connected to.

    RAMPS.png

    ramps1-4connectors.png

    T0 is the extruder
    T1 is the bed
     
    #6 mark tomlinson, Feb 1, 2016
  7. John H

    John H Member

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    Thank you again , gonna inspect around to see a loose wire .. I'll keep u posted
     
    #7 John H, Feb 1, 2016
  8. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    If the thermistor is working and installed on the correct pins, it will never read 0°. It should read near to your current ambient temperature, unless of course your printer is in a freezer. If it is truly 0°C then it is not hooked up to the correct pins or is broken somehow. Example, With the power off and only USB connected my bed is reading 21°-22°C and so it the extruder.
     
    #8 WheresWaldo, Feb 1, 2016
  9. John H

    John H Member

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    So I very carefully traced all wires to see if there were any breaks or loose connections. Nothing all good .. But my information was wrong before when I said the bed was at zero . It's actually around 20 , but dose not move If I preheat it stays at 20 ..
     
    #9 John H, Feb 1, 2016
  10. John H

    John H Member

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    Thanks Waldo
     
    #10 John H, Feb 1, 2016
  11. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    That is a different issue. That means that either the bed heater is bad OR the wiring to the Bed heater is disconnected or bad OR lastly the RAMPS itself could have a bad transistor (a MOSFET) on that output port or the Polyfuse is bad on that same port. Neither of which is really user serviceable, you would get a new ramps in that case most likely.

    Check the wiring to the heater itself next.
     
    #11 mark tomlinson, Feb 1, 2016
  12. John H

    John H Member

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    So it dosnt look like its a loose or broken wire visually .. I'm gonna check continuity to the heater wires to defiantly check that . So what else should I check /how?
     
    #12 John H, Feb 1, 2016
  13. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Measure the resistance/continuity of the heater bed from the RAMPS (power off).
    Measure the voltage on the RAMPS output port to the heated bed (D8) with the RAMPS trying to heat the bed.
    You should have 12v at least there. If it reads 0 then that is a bad MOSFET (or perhaps the polyfuse) on that channel.
     
    #13 mark tomlinson, Feb 1, 2016

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