My friend has a question. I am sorry that my wording of music electronics is in-correct, but doing my best to interpret what he asked. 
He has MACKIE CFX20 mixer that has no sound except the SUB is on. He is trying to figure out how the inputs (mic, stereo) are being connected to the main outputs (L, R).
When looking at the schematics or the mixer itself, the channels are going through AUX and FX, and it seems that the one that is going out to Main output is going through SUB.
Is there anyone who can see a path that goes directly to the Main output.

He has MACKIE CFX20 mixer that has no sound except the SUB is on. He is trying to figure out how the inputs (mic, stereo) are being connected to the main outputs (L, R).
When looking at the schematics or the mixer itself, the channels are going through AUX and FX, and it seems that the one that is going out to Main output is going through SUB.
Is there anyone who can see a path that goes directly to the Main output.