Heater fault at Jobstart

Bipotronic

Hi,

Firmware Electronics: Duet 0.85
Firmware Version: 1.23 (2018-12-24b1)
Web Interface Version: 1.22.5

currently everytime when i start my print, a few seconds later i get a "Heater Fault" error message "Error: Heating fault on heater 1, temperature excursion exceeded 15.0°C".

When i heat up up the Hotend 0 there are no problems, also the temperature graph looks very smooth. But when i start the print the temperature graph behaves very strange and drops down.

You can see it in the picture i attached. At the first drop of the heater graph i started the print.

I also did tune the Heater with "M303 H1 S210" and took the given values for the PID - Controller.

dc42

My guess is that the temperature drops suddenly when the print cooling fan turns on. Point the fan at the print, not at the heater block. Put a silicone sock over the heater block if you don't have one already, then tune the heater again. There is a wiki page about spurious heater faults, in the Troubleshooting section.

Bipotronic

i use a water cooled hotend, and the cooling proces is always on. So there could not be an effect to the temperature.

After the breakdown of the Heater, i cleard the Heater Fault and set the target temperature to 210°C again. This time the heater does not reach the target temperature and the "Heater Fault" appears again.

0_1556551073369_Temp-Chart 2.JPG

Here an example of my first lines in the G-Code:

G90
M83
M140 S60
M104 S210 T0
M104 S215 T1
G28 ; home all axes
; process
; layer 1, Z = 0.200
T1
G1 E-10.0000 F1800

timcurtis67

Check thermistor wiring? Or a bad Thermistor? Maybe when you move the head around it causes an issue?

The fact that you can't reach the target temp on the second try tells me it's more of a random problem.

dc42

@philipp-r, I was referring to the print cooling fan. Not the heatsink cooling system. The temperature graph you included in your first post looks like a classic case of the print cooling fan turning on and causing a fast but not instant temperature drop. But the one you included in your last post suggests bad thermistor wiring instead.

Bipotronic

i also do not use a "print cooling fan", but i rewired the thermistor and heater cables and now it seems to work. Thanks for your help

timcurtis67

@philipp-r Glad you got it sorted out.