I am cross posting this onto a few forums in hopes of finding someone that can give me a tip or three.
I have this mixer and it is very sentimental. I had a lightning strike years ago and the board went out and an ex-employee that was a good tech had it up and running in about 15 minutes. I didn't think twice about it and was happy and since then I've lost touch with him. Anyway, this board has a separate power supply providing 48V Phantom and +/- 15 V on the rails for the Audio circuit. When I finally started using the board again after a long hiatus, the board typically would run for several days but would intermittently blow the audio fuses. I could put another set of fuses in and it wouldn't blow the fuse for sometimes days, sometimes weeks. Today the fuses blew and when I replaced I immediately could hear a "flickering" sound from the board (it was audio) and it blew the fuses. I unplugged the power supply from the board and the fuses don't blow. So I am thinking I now have to trace the audio section of the board. It has two 8 channel extensions so my first thought would be to remove one or both and see if the fuses still blow. If not then I can just work on the extensions. If so that would indicate the main board. The board with extensions is 32x8x2.
With that being said, I have a set of schematics I'm about to dive into but wanted to get anyone's incite that might be familiar with fixing / modding mixers on what would be the most logical thing to look for first. I have to clean the pots anyway so the board has to be maintenanced and now, regrettably, fixed.