Check the level setting switches. They can cause problems.

Martin

Thanks, but the fault comes at the same time on Phono and Mic. So it has to be a common component. It has been playing flawlessly for 2,5 hours now, until the bonfire just returned.

The bonfire is thinner in Mic than on Phono, but pretty much the same pattern. But it is a much thinner sound compared to the rich crackling in the Phono. Strange..

I don't think it will help, but I'll try replacing the transistors, and will be back :)

Edit, I also did check the level switches. Together with cold solder joints and all other switches. But you are right, it does sound like a dirty switch. I have operated them all, and there is no easy indications of a dirty switch. 

I'm no quitter, but I find the schematics for this amp hard to read.

There is something wrong in my pri-amp. Now I have the same sparkling noise on all inputs. A weak ago it was only phono & Mic.

On the right side, I measure OK on transistor 41 & 56. But on 86 & 99 the voltages are too high. Tried to replace them, same result.

On transistor 86 I get 33V on collector, 22V on emitter and 14V on base.

On transistor 99 I get 33V on collector, 22V on emitter and 33V on base.

Transistor 171 and 180 measure according to schematics.

Any expert on reading the diagram that can guide me in the right direction.

I'm hoping the dispair at the moment will make he love my Beolab even more when done 😎