I have just built my first AMP10. It passed the 5V test a few times, I could even get it to react on the mute switch, but now I don't get any reaction.

Details:

Transformer: 300VA 220V -> 2* 18V. A 600mA Fuse blows most of the time, 1A is pretty solid, 1.4A even more, 2A doesn't blow. I guess thats the startup Current from the Transformer
I can measure 20V AC on the Input-Terminals J4 and J5.
I could measure 25V DC over the main Capacitors C80-C83, but now I get 0V there.
I could measure 25V DC over C150.
I could set the Jumper from Mute to unmute, and voltage on the LED would drop from 5V to 0V (no LED connected).
Now I get 20V DC/25V AC on the rectifiers, but nowhere else... (apart from the Input-Terminals, obviously)

So I am looking for hints how to debug this my self, or somebody in West-Germany (NRW) who could have a look and perhaps fix this....