Extruder over heats on power up

[pf_drj]

Just received my Prusa i3 aluminum 4 days ago. Completed the build last night and when I turn on the machine the extruder over heats. I have no control over the temp at all. The only way to get the temp down is to turn off the machine. Please help!

[William]

Hi,
You can try unplugging all the wires except for the power cable and the lcd cable to see how it goes.

[russellz]

Hi,
You can try unplugging all the wires except for the power cable and the lcd cable to see how it goes.

Well that will certainly stop the extruder overheating!
It may help if you leave the extruder heater and then check with a multimeter across the pins for the extruder heater. If there is 12 V there it is most likely a faulty mosfet on the GT2560 board as the heater shouldn't be powered up on switch on.

Russell.

[William]

Hi,@Russell
You're right.That's the next step.