Extruder temperature varies wildly - what's wrong?

Vertex 3D Printer Vertex - Issues while printing
1

OK, something is clearly wrong. Please have a look at these temperature graphs for my last print, using Repetier Host and Cura. You can see the temperature is jumping about all over the place. I don’t remember it ever doing this - can someone else please post a screenshot of their temps while printing PLA?

https://www.dropbox.com/s/0i1v4xupn5pjmra/Screenshot%202015-02-06%2015.55.11.png?dl=0

@Velleman - If something has failed or isn’t working properly (thermistor, heating element?), how do I know which to get replaced? It gets worse the longer it prints:

https://www.dropbox.com/s/0i1v4xupn5pjmra/Screenshot%202015-02-06%2015.55.11.png?dl=0

Until the nozzle eventually starts to block and the flow gets disrupted.

2

Looking at the graph and your description kind of makes me think you have a loose wire going from the heater to the connection on the print head board or maybe one of the connectors is loose on the control board.

3

Obviously wrong. I’d check the wires of the heater block. Isn’t one got loose on the heater board? Or else the wires from the controller board to the heater board.

4

Yep, loose wire! Phew! Thanks. Actually I think that must happened with my first print using the black PLA.

5

Glad to hear everything is OK.