Hi, I have just built 2 K8060 amplifier kits to make 2 active speakers. 1 amplifier works perfectly, the other doesn’t: I put a 60w light bulb in series with the mains for first switch on as advised in the instructions. The bulb lights and stays on. On full input volume, with the bulb lit, a very low output level can be heard from the speakers. Transistor 8 gets too hot to touch within 30 seconds.
the instructions advise disconnecting and checking wiring and soldering: I have done this and can’t find no dry joins or track shorts, even using a x30 magnifying glass.
Is there anything I can do to fault find or is it a matter of progressively replacing all the components till I find what’s broken?
Is it worth fault finding, or is it going to be better binning it and getting another?
Is there any sort of warranty from Velleman for a self build kit?
I am a novice at electronic theory, capable of following construction instructions to a high standard but I don’t understand the theory, so simple answers are good 
Thanks
Ron