Heater Fault Troubleshooting

[jgbowman]

The temperature on my heater is not increasing. I believe I have the wiring correct but have issues in the configuration. Any suggestions?

[jgbowman]

@dc42 please help

[paboman]

you have some kind of wiring problem, as you can see you have a lot of 2000°C spikes in the graph.
maybe loose connection

[jgbowman]

@paboman I'm still trying to figure out the wiring issues for the pt100 sensor, but I believe that should be separate from the actual heaters.

[Phaedrux]

Interference in pt100 wiring can be mitigated by using a twisted 4 wire connection.

https://duet3d.dozuki.com/Wiki/Connecting_PT100_temperature_sensors

[jgbowman]

@phaedrux I only have a two-wire pt100 sensor. Both sensors are wired the same exact way, however one of them works while the other is completely dysfunctional.

[Phaedrux]

Each of those two wires can be split into another 2 wires.

https://miscsolutions.wordpress.com/2016/06/25/more-delta-printer-upgrades-wifi-and-silence/

It really is the best way to run a pt100. Highly fault tolerant.

You can attempt to isolate the issue by separating the pt100 wires physically from any other wiring and see if the reading spikes are resolved.

[T3P3Tony]

@jgbowman those spikes look like more than noise to me. As others have mentioned you can get intermittent spikes from noise however the first one is really long and looks like a poor connection to me (or possibly a faulty PT100 daughterboard).

Can you check the connection and try sawapping the channels to see if the 2000C fault follows the PT100 sensor.

[jgbowman]

@T3P3Tony, @dc42 , We have figured out the Heaters Fault configuration. We are now having issues configuring the Z-axis. Any suggestions as to why the manual Z-Bed Probing is asking us to adjust the X-Axis?

[dc42]

@jgbowman, it's because you have mismatched versions of the firmware and Duet Web Control.

[jgbowman]

@dc42 I updated all of my firmware to 1.21 and this successfully switched the setting from x-axis to z-axis. Only thing is that I now get this error when trying to manually probe the z-axis.

[dc42]

For now you will need to add command M564 H0 to config.g to allow movement of an axis before it is homed. This will be fixed in future firmware and DWC revisions.

[jgbowman]

@dc42 I added it here, but I'm still getting the same result.

[dc42]

Odd, that should have fixed it. Please run M564 without parameters and see whether it says movement is allowed when the axis concerned is not homed.

[mrehorstdmd]

@jgbowman

Where did you get the PT100 sensor? More importantly, what is the insulation material on the leads?

I recently tried to use some cheapo PT100 sensors with teflon insulation on the leads and after a couple weeks of occasional ABS printing I started getting the same sort of weird heater faults you did, including the spikes to 2k. I checked the resistance between the PT100 leads and the metal casing and found that one of the leads shorted to the case. The case is in contact with the heater block, which in my printer is grounded.

Swapping in a new PT100 sensor will fix the problem temporarily, until the teflon wire insulation inside the sensor housing breaks down due to the high temperature.

Teflon insulation going into the metal sensor housing is a no-go for high temperature use. The E3D PT100 sensor has fiberglass insulation which should be reliable at high temperatures.

[jgbowman]

@dc42 It says movement before homing is not permitted. All of the firmware is updated to 1.21 except for the paneldue, could that be the problem?

[jgbowman]

@mrehorstdmd Not sure where my boss got the sensors, but I've tried to switch out a couple of them, so i'm pretty sure it's either a wiring or configuration issue. I ordered a new daughterboard because that seems like the most likely fix. For now i have got it working with regular thermistors though.

[mrehorstdmd]

@jgbowman

Do they have Teflon insulation on the wires?

[jgbowman]

@mrehorstdmd i believe so

[mrehorstdmd]

@jgbowman

Teflon breaks down at ABS print temperatures. If the Teflon breaks down inside the casing, it will short to the case and that will cause erratic behavior. Check the resistance between the wires and the metal casing of the sensor- any noninfinite reading is bad.

I had the same problem a week ago. Swapping in a new PT100 of the same type will fix it temporarily, until the Teflon breaks down.

PT100 sensors that are going to be used in the hot-end should have fiberglass insulation on the leads. E3D's PT100 sensor does.