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Answered Temp fell too much error

Discussion in 'Troubleshooting' started by Erin-Ellen Winfree, Oct 8, 2018.

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  1. Erin-Ellen Winfree

    Erin-Ellen Winfree Member

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    I know this is a common problem, but I've been all over the forums and the internet in general and I have yet to solve it. Stay with me for a moment if you will. I'll start at the beginning

    I have a Robo3d R1+ and the fan in the power supply went out. While replacing the fan, we noticed some oil on one of the large capacitors. We thought that was probably bad and I'm not afraid of a little soldering so we ordered a replacement and I put it in. The only problem being that it ended up being a physically larger capacitor than the old one. It is still 680uf 250v though.

    Now, as long as we had the printer torn down, we decided to finally install our E3D v6 hot end. We bought it awhile back, but the stock end was doing pretty well so we just kept putting it off. I followed the forum thread here and everything seems to be hooked up properly and after a lot of reading I have installed the Marlin firmware for the Robo with the altered values(indicated in the install thread). However, I can't get it to print a single thing anymore.

    Initially, it printed probably halfway through a 2.5 hour model, but now I'm not getting even through the second base layer. I'm at somewhat of a loss on what to do next. Everything I read seems to indicate a loose cable, but I have everything zip tied together fairly tightly. I was going to print a cable chain for all the wires next but I can't get a reliable print anymore.

    Do you guys think the different sized capacitor could be the problem? I didn't think so, but I don't know electrical components that well. Any advice is much appreciated.
     
    #1 Erin-Ellen Winfree, Oct 8, 2018
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, I'll vote NO on the capacitor.

    Regardless of what you see when the error is raised by the firmware it is because it saw temperature drop. Only thing involved in that is the thermistor, the wiring and connectors and the RAMPS (and Arduino obviously). So those are your suspects. I guess in some rare circumstance the capacitor could be bad and severe ripple on the DC supply is making the Arduino lose it's mind (but I'd bet against that).

    It can be really tough to 'see' this happen because the firmware samples the temperature so much faster than any of the USB attached software UI programs can display it. Plus this is often a loose connection or wire or an actual faulty/intermittent thermistor and the total of all of this is that you can get this error and never see the change from the computer attached. If the firmware is sampling it 100 times a second the USB attached computer is not reading it that fast and a single bad data point is all the firmware needs to see to raise the error.

    Still Marlin raised the error it is because the temperature suddenly fell (and usually came right back, but that is not the point).

    All of the other threads you read have all of the same suggestions already. Try wiggling the harness near the hotend and back to the RAMPS. If you can reproduce the error manually you can rest assured it is a loose interconnect. If it is not a loose connection / bad solder joint then it can be a damaged thermistor or bad electronics (RAMPS or Arduino) but those generally fail in more obvious ways than just a flaky analog input :) The reason we always say loose connection or wire to the thermistor or RAMPS is because it usually comes/goes with movement of the wiring harness as the extruder platform is moved around while printing. A wire that is broken internally and occasionally fails open will do this. You can't see that. A connection that is cold-soldered internally and occasionally presents open-circuit will do the same.
     
    #2 mark tomlinson, Oct 9, 2018
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  3. Erin-Ellen Winfree

    Erin-Ellen Winfree Member

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    I appreciate the quick and detailed reply. I believe I have fixed it though! At least, I got a print to complete. I noticed another symptom after the error and tracked down another thread.

    The whole printer(lights and all) was shutting off. When replacing the heater fan we also replaced the case fan, and like a fool, I thought it should be pulling hot air away from the RAMPS board. Flipped it around to blow out and got through the whole print.

    Provided that was actually my biggest problem, I just need to dial in settings on the actual processes now that I am running a E3D. The part had curved up corners and some stringing between two parts that stick up.

    Again, thanks for the forums.
     
    #3 Erin-Ellen Winfree, Oct 9, 2018
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Awesome, yea the bottom cover meant that the boards could over heat and if they do ... weird things happen. :)
     
    #4 mark tomlinson, Oct 9, 2018
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