Friend gave me this Aiwa system since she doesnt use it. No manual. Not tech savy. Want to make sure the 3 CD changer works. There are 2 power buttons on the system. Not sure if both have to be on. Seems like its going but no sound. Stuck speaker wires in 6 amp connections in the back. This is a stereo system with radio, CD, karaoke, and cassette. Also not sure what the different programs are, Can anyone help. Thanks