: I've been presented with this console for repair with instruction to "make it reliable". Apparently it has some history of burning up components on the channel cards (TL072's & the 22½ current limiters). I notice all of the XLR's have pin-1 tied to the shell, which is a bit unusual by today's standards. Also the ground portion of the channel & master sections appears to be split (fairly common practice). I suspect reliability could be improved by re-configuring the grounds so as not to rely on continuity of XLR case to chassis. Anyone have a proven modification and/or schematics?
: Thanks -
: (BTW - I made my first band paycheck playing through a "Concert Lead", as I recall...)
Hello;
I worked for Sunn up until Fender purchased it in 1984. I still own a 2224 which is in perfect condition. I have schematics. The grounds you refer to were modified by connecting all pin 1s together and ground at the tie point for the green AC cord ground point. The bus cabling that connect the channels together is notorious for having bad connections at the molex connector. if you solder all of the buss wires to the molex pins your gremlins will go away entirely. The only other problem we had with these boards was a tendancy to break the pan pots (front panel flex) if it was dropped. If your board has a green LED in the reverb clip position it is an early model. If the LED is red then you have a post 1981 board with a type 0011 reverb pan (long not folded) and a much better sounding verb. I never heard of even one board failing by burning up. They are extremely punchy boards with lots-o-headroom with real nice EQs.
