I once tested a thermometer and pointed it directly to the xml emitter of my tk21. It reached like 140 Celsius on turbo and it kept rising. I dont know if there s some kind of interference since the thermometer uses IR to measure things and the LED might put out some IR too. Im not a specialist but 140 degrees is hotter than my CPU. And it could easily burn my hand in case i touch it. Well that was me trying to find an answer to the same question.