this is a tri-power product with 3 amplifiers in it. the monitor power amp works like normal. but the two main speaker amps seem to have blown a fuse or something the red limiter lights are on which normally means it has too much signal running through it. (MAXED OUT) but even with nothing pluged in the red limiter lights are on and no sound will come out of the main speakers. if its just a fuse.. i dont know where the fuse box is on this PA. (my last PA it was easy to replace the fuse)