From the schematic, the signal path for the Coliseum 300 goes something like this. The input signal goes thru a gain control and is optionally routed thru the compressor then the Contour switch. Next in line is the multi band equalizer. Next comes the Effects Send/Return. Next is the Master Volume control. There is a Preamp Out jack that can get it's signal 'Pre master', 'Post master' or 'Post xover'. I'm not sure how the selection is accomplished, it looks like a jumper on the circuit board from the schematic.
From the Effects Return, the signal is routed thru the Master Volume and then to the Crossover circuit. The Frequency control affects both the high and low outputs simultaneously. The Hi and Lo outputs of the crossover each have Effects Loop Send/Return jacks. Next there is a circuit that combines the high and low signals from the Hi and Lo Return jacks. This signal is routed to the Power Amp Input jack where it dead ends if a plug is inserted into that jack.
The last little bit of circuitry is the CMOS signal shaper and then the signal goes to the power amp.
don't suppose you'd feel like going into a bit more detail? this is the first solid state amp that i've had trouble with.
You really shouldn't be messing around inside the amp if you don't have the training and experience necessary to safely do what repairs are necessary. Serious harm or death could result.
