Testing the motherboard, heater and AD597 thermocouple

Today I did a few tests and when I started I had some troubles getting the connection right trough Cura. The weird part was that I was able to upload firmware to the printer but than I could not establish the connection run the bed-leveling-wizard in Cura.

A few hours of research on the internet and digging trough forums didnt give me any cleus. I decided to continue and test my hot-end electronics.

One little problem I came accros was that the thermocouple should have 2 diffirent color wires Red (+) and Blue(-). Mine had 2 white wires so I think the colors must have faded off. I could not find a way to chek it's polarity so I just marked one wire and connectet them randomly to my AD597 thermocouple board. I carefully switched the power supply on and BOOM! bed smell, flash of light, smoke and siddering noise!! I turned it off in a split second!

After calming down I disconnected the power supply and start looking for possible damage. One wire of the thermocouple that was white was now completeley black over the entire length. I wasn't looking good for me... I decidet to twist the wires and just try again (this time a little tense) I plugged the power back in and turned it on again. No smoke, everything looked ok. So I retryed connecting to Cura and guess what? It worked! So I ran a test program and everything worked perfectly the heater cartridge heated up and I could read the temperature from my laptop. Big release that I had not blew anything up. I marked the wires and called it for the night.