nozzle temp reads 398.3C

[Maleny]

I have posted this on the general discussion page but maybe it would be better here so I am posting it again.


I have just replaced the hot end on my Mini (Mk1) and now the nozzle will not heat, probably because according to the maintenance screen the nozzle temp is 398.3C, I have checked the wiring conductivity as far as the ribbon cable plug and there is no problem there.
I still have my old unit so replaced it and the same thing is happening.
Next I compared them, they both give the same readings which are heater element resistance 9 ohms and sensor resistance about 114 ohms at room temp.
I have connected a resistor decade box across the sensor wires and slowly reduced the resistance, there is no change in the reading.
I have heated them both with my hot air gun and the resistance rises with the temp so assume they are working OK.
There are no voltage readings between any of the 4 wires at the head but I do see 0.86 volts between the heater wires and the chassis of the printer.
Anyone have any Ideas as to were I go from here?

[tobih]

Hello,
I'm facing a similar problem. My temperature says 387.9 °C. First I thought it was because of the +15 °C in my cellar, cooling everything down. Heating the nozzle, turning off and on the mini again seems to solve the problem for the moment (had to repeat several times). But what causes that error? I don't know... Tiertime, please help

[tel]

This is normally either the white ribbon cable or the rainbow cable (more so the white ribbon cable I think). Try reseating the cables to see if that helps. Other thing that normally points to a problem here is to check the nozzle temp before you start heating anything up (ie as soon as you turn it on and initialise). The nozzle temp should be around room temperature. If it is already showing a much higher temperature it points to the cable being the problem.

[tobih]

Disassembled extruder-part and double checked the items suggested. I can not find any problems. Checked the NTC with an Ohm-metre, seems to be perfectly o.k. Checked cables at the mainboard, too.
Starting up! software and initialising the printer, nozzle temperature shows values beyond 350 °C.
Maybe an issue with the mainboard?

[tobih]

Maleny, could you solve the problem? I am still facing it. Just to be sure: te thermistor is a PTC100 and not a NTC, right?
I double-checked all the wires, measured the ribbon cables and so on. I tried a different PT100 sensor measuring about 120 Ohm at room temperature, but up-software says 390 °C.
Mainboard? MCU?

[tel]

It may be. Have you logged a support ticket?

[tobih]

I have changed the extruder stepper motor: being optimistic now, temperature showing normal values now. Knock on wood!

[tobih]

Has worked for several hours, now same error again.
How do I open a support ticket, and where?