K8060 - TIP147 burned

Hello,

I built the Velleman K8060 kit.

Everything has been checked several times, the direction of the components, their value, the voltages of the transformer, etc.

Everything is in order.

The bias of RV1 has been set to 10.2mv (tested with a voltmeter).

The speaker is 8 ohms and was plugged in the right side.

The audio source is an mp3 player, which works great on another amplifier.

As soon as I sent sound (at a low level) to the input of the IN and GND terminals (connected in the right direction), the TIP147 transistor immediately smoked and burned.

The radiator is properly isolated from the two transistors. Nothing touches. The thermal paste is in place. I have already made many other montages, without any problems.
I do not understand why.

Attached photos:

Thank you very much for helping me understand what happened!

Dear,

It is difficult for us to solve this at distance, without being able to thoroughly inspect everything.
I hereby propose to return the product back to us, to the following address:

Attn Tech. Dep.
Velleman NV.
Legen Heirweg 33
9890 Gavere
BE Belgium

Regards,
Velleman Support

I approached my dealer, who offered to return the circuit to him. He can return it to you for analysis.
Thank you!