Ultimaker isn't working, thermocouple defect?

[maurice 1]

I've assembled the Ultimaker, and connected it to the Mac. Strangely, the Mac won't boot if the USB cable is connected to the Ultimaker, even is the Ultimaker is switched off. The Mac runs OSX 10.6.8 and Cura 12.11 (12.12 crashes under 10.6). I've used the wizard, updated the firmware (that even works when the power to the Ultimaker is off, is the Arduino powered by USB?). In the next step I test the hardware, the communications work, and the heater also (though maybe not always, but sometimes I feel the printhead heating up). But Cura can't see the temperature rise, it stops with an error. I've checked the thermocouple, it is connected correctly, its wires are not broken (I measure a resistance of about 3 Ohm when not connected to the block). I've exchanged the wires, using the wires for the second thermocouple, all no go.

[maurice 1]

I've figured this out myself, the wires of the thermocouple need to be connected the other way around, the red one must be connected to the left terminal on top of the printhead, not the right.

[Daid 288]

I've figured this out myself, the wires of the thermocouple need to be connected the other way around, the red one must be connected to the left terminal on top of the printhead, not the right.

Yes, this has been an error in one of our latest batches of thermocouples. There have been a small amount of thermocouples which are wired the wrong way around. (Red/yellow swapped) they work fine, but only the wire colors are wrong.