Thermo regulation out of control and overheating!

[beratchu 0]

I need some help here...

One of the last prints the heating just started to get out of control.

There is no error message but the measured temperature is wrong very often.

Sometimes its starts fine, i start a print, heating up to 215 and printing a bit, extrusion good.

After a few seconds the measured temperature goes down slowly to 210 and stays somewhere there but the heater block is heating up more and more and boiling the plastic getting 300 and more!

Turning the printer of and on again it is showing a wrong temperature again.

I already exchanged the Thermocouple sensor but same behavior.

Since these spare parts are not quite cheap and take a while to arrive i don't want to test one by one.

Can it be the Thermocouple Transmitter, other electronics or maybe something in the firmware?

I think cura crashed one time and the error might be since then.

 

[gr5 2,005]

It's usually the wire running from the top of the print head back to the bottom of the machine.

Measure the voltage at the top of the tiny circuit board. After passing through the circuit board, the voltage at the circuit board is equal to the temperature such that 0v = 0C and 5V = 500C (200mv = 20C). So check the voltage and see if you agree. Raise the temp to around 100C (test with water on aluminum block) and it should read about 110C when water starts boiling. If this is working fine but ulticontroller is displaying different temp then it is indeed that wire. There is a spare wire.

Note that often the fan can interfere with the temp when in PWM mode. Try turning the fan to 50% and see if that makes the temperature change significantly.

It could also be the thermocouple or the circuit board on top of the print head.

Also make sure the small board on the print head is properly getting 5V.

 

[beratchu 0]

SOLVED

Thank you, it really was the wire that was going from the board to the Thermocouple Transmitter.

After pushing it better in the socket it worked again.

Similar Problem was described in this post:

http://umforum.ultimaker.com/index.php?/topic/3839-floating-temperature-values-cause-overheating-of-hotend/

For dual extrusion i need both cables working, so i should order a new one and somehow fix the cable in the plug to have it moving less.