I picked up a second hand Epiphone by Gibson pr350 12-string with the epiphonic five preamp. It has a little gray button with the letters BC by it and one red LED. When I push that BC button with a normal guitar chord plugged in instead of a low z cord plugged in, the red light simply comes on and then it goes off when I let go of the gray button. What is the gray button should the red light stay on? And also when I plug the guitar in with a the three prong low z chord I get no sound through my amp. Any and all thoughts/manuals would be appreciated. Do I have a dud here or what?
