Hello, I have problems with k8060 kit blowing up. The problem is that R19, R20, power and sometimes other transistors blow up after some time. Mostly when I turn up the volume. I already got 3 kits and even tried making my own pcb - same thing happened.
One recent kit blown when I turned up the volume instantly, then I left other one on ~60% volume and after a few hours it blown also. The interesting thing with these two was that R19 and R20 cracked in half and were really hot. I noticed that they were warm when operating also.
My transformer is 2x28V and I have additional 10000uf capacitors after the diode bridge (using external, not the one on the pcb). DC voltages are ~38V. I also have a decent heatsink so overheating is not a problem here. I thought the problem could be my 3.3ohm speaker but cable was quite long and multimeter read 4.5ohm.
I replaced all components like 20 times and same thing keeps happening. What could be the cause of this?
Impossible to tell without being able to examine your circuit and/or hook-up.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.
I can’t take pictures of the solder side at the moment but I haven’t done any modifications there. Soldering is clean and smooth.
You can see both resistors are cracked. Could this happen because o wrong quiescent current setting? I’ve set it exactly how manual said but I remember it was very sensitive and hard to adjust.
-Putting the power transistors at a remote location and connecting them with wires is a guarantee for troubles, in most cases in the form of oscillation.
-Transistor T6 must make a very good thermal contact with the heatsink, to ensure proper biasing when temperature changes.
-Some power diodes seem to be bridged???
The overall assembly is very poor and violates the rules of good engineering practice. We strongly suggest to mount and hook-up the amps as described in the manual.
I had to do so because of the radiator I had. The sound quality was still quite nice though.
I’ll keep that in mind, however I don’t think that this could be the cause of blowing up as heatsink wasn’t even warm when this happened.
As I mentioned in the first post, I’m using external diode bridge and additional 10000uf capacitors so I shortened some of the diodes as voltage is already DC
