Check if one channel is inoperative with all sources. For example, if the problem only exists with a DVD but does not exist with FM or tape, the problem could be the cable between the DVD player and the receiver. Replace the cable and check to see if the problem persists. Also, check to be sure the balance control is centered. If the problem persists, continue to step two.
Swap the right and left channel speakers. If the left channel does not work when connected to the right speaker, the problem is with the right speaker. If the left channel works with the right channel speaker, the problem is not the speaker but elsewhere in the system. Proceed to step three. Note: Always turn off the system when removing or replacing cables or speaker wires.
Working backwards from the speaker to the receiver, thoroughly check the speaker wire for any breaks or broken connections. If there are splices in the wire, check to be sure that the splice is still making a good connection. If you’re not sure, replace the speaker wire and check the system again. Make certain that the speaker wire is securely connected to the speaker terminals on the back of the receiver and that there are no frayed wires touching the metal back panel (even one strand could cause a problem). If the speaker wire is in good condition, the problem exists in the amplifier or receiver.