This is a nice german quality hybrid tube/solid state channel strip. It had developed a problem with it’s gate not working properly so I popped the hood and checked out what was going on.
After some general cleaning I started disassembling the insides. This was used in a bass rig(?) and in places where people smoke a lot so there was some yellow/brownish gunk around. Checked for weird looking/burned components and found none. Next I buzzed all electrolytics with my ESR meter and they measured ok. Cleaned all IC-sockets, and then moved on to potentiometers. You have to pretty much take everything out to get into the potentiometers on the front panel. Cleaning the gate pot didn’t help so I installed a new one. After that gate was functioning normally. Hooray!
Decided to check the other pots as well since I had it open and noticed a scratchy distortion pot which came back to normal after some cleaning (using PRF 7-78) and vigorous rotating.
Good sounding and well built channel strip! For future upgrades there are even holes for Lundahl transformers on the pcb and a ribbon cable for digital output card. I added some gut shots for your pleasure :)
There’s a newer version of this preamp available at Amazon, check it out here.