Heater Fault when Starting Print
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Hello all,
So I rustled through previous posts and one post appeared to come close (This one) but I don't think it was the exact same issue (plus I didn't see anything from the originator on a solution).
I just replaced the Mightyboard on my FlashForge Creator Pro with a Duet 2 Maestro board. I didn't change out the K-Type Thermocouples on the hot end so I ordered a daughterboard for the Maestro. I labeled all wires, followed the wiring diagrams exactly, and made sure to even wind stepper wire pairs to minimize EMF noise to the Thermocouple cables. Post replacement, I can set temperatures for my hot end on both extruders without a problem. The issue arises, however, when I go to start a job. When the gcode file is loaded, the bed heats up, the hot end(s) heat up, all with no problem, but as soon as the print starts (and it looks like it completes the homing procedure with no problem), ONLY extruder two faults by going to 2000C and I get a message saying that the wire is shorted. I checked the wiring and to my eye, nothing appears shorted from the daughterboard onward to the thermocouple. I would think that if there was a short, it would appear immediately upon trying to heat the hot end up.
Some things to note:
- It's only extruder 1 thermocouple being affected.
- The wiring for the thermocouple is grouped with the extruder 0 thermocouple, the hot end fans, hot end heaters, and both sets of extruder stepper wires.
- The printer can process a hot end purge on extruder 0 prior to the failure, which tells me the signal from the stepper motor doesn't appear to be affecting the thermocouple signal.
- I tried two different slicers to make sure it wasn't a slicer issue (Simplify3D V5 vs Cura 5.1.0) but same issue both times.
- Investigating gcode didn't seem to point to anything glaring but I'm not sure.
Has anyone had any issues like this and have you found a solution?
I'm currently working 6a-6p so I will update any requests for information as I can, but I figured I could still get the ball rolling for some insight. Any help is appreciated! I do also have some stepper noise during motion that wasn't there before the board swap but I'm not as worried about that.
Currently my worst case scenario for this is that during my next down time if I still haven't had any success, I may look into replacing the K-Type Thermocouple with regular thermistors. Less finicky and a better plug-and-play option for the Duet, but I already have the thermocouples installed and ready to go so naturally I'd like to try and get that working.
Thanks again for any help I can get!
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@MobiusOne thermocouples will be a constant source of troubles. Personally I would replace them sooner rather than later.
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@MobiusOne here are some things to check:
- Check with a multimeter that there is no continuity between the thermocouple wires and the hot end metalwork. Some types of thermocouple have one wire connected to the case, and those won't work well in 3D printers.
- Measure the resistance of each thermocouple between the terminals on the daughter board. It should be very low. Compare the resistances of the two thermocouples. If the resistance of the one that faults is significantly higher than the one that doesn't, then either that thermocouple is failing or there is a bad connection in the wiring.
- Try disconnecting the extruder motor at the Duet (do this with power off!) and running a print. If the thermocouple doesn't fault, that confirms the problem is that the thermocouple wires are picking up interference from the extruder wires.
I recall we had one customer who had problems with thermocouples picking up interference, which he solved by increasing the values of the filter capacitors on the daughter board.
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Thanks for all the input! I'm hoping to have time tonight to do some investigating finally, so I'll update my results then! Thanks again!
