Problem: crackling noise on the Centre Bus, really loud, reduces Noise to Signal Ratio to 40dB.
Solution: I turned every single bucket of channels off, until the noise was gone. The noise came from my first bucket of channels 1 - 8. I started removing Channel 1, then switched the bucket on again - noise was still there. Continued removing channels until I found Channel 5 was the source of the Noise.
After removing that channel I still noticed some "antistatic" crackling in the LF and Surround Busses. Lower than the noise from Channel 5, but still there.
What I found really interesting was, that if I turned all buckets off, but Master Section still on, I still had this noise on the monitors.
So I decided to go trough the whole console, removing all channels. I found 3 more channels that induced some noise into the different summing busses. I found them with the buckets switched off! I also switched the Float Button on all channels.
So the problem is now solved by removing a total of 4 channels. Will have to find out at another time what the problems of these channels are. Will probably swap some cards, perhaps - as sintech suggested previously - look at the Film Pan Card and also the Quad Pan Buffer on the Group Card (IC 14) and the CMOS Logic Chip that is controlling JFET RG14.
