I am currently digging into electronics and today I experienced a strange problem.
I rebuild an oscillator circuit with the 30106 IC and I wanted to measure with my new oscilloscope (it is a china thing called DSO FNIRSI-150), whether there is something oscillating. As I connected only the oscilloscope's ground crocodile clip to the ground on the breadboard, the IC started to produce steam like an old locomotive and the 3 upper left pins of the IC produced so much heat that the breadboard was melting too in this area.
Why was this happening? - I could not find any explanation online. There are some threads discussing grounding problems with AC ground, but since the power supply of my very cheap oscilloscope does not utilize the ground connection of the power outlet, they might not be applicable here or am I wrong?
Also why does the IC melted down? - If I had (I don't know how) produced a short circuit with the ground of the switching power supply that powers the circuit and the ground of the oscilloscope, then why wasn't the oscilloscope damaged but the circuit IC?
I would highly appreciate any answer that gives me some clarity so that I won't burn any chips in the future :)
Here is an annotated image of the circuit: