Polk Audio, an American audio company founded in 1972, has created an excellent line of subwoofers for home theater systems. The subwoofers feature a night mode for quieter bass during the evening and the Polk Room Optimization, (PRO) to produce the best sound at the touch of a button on the remote. Problems with Polk subwoofers can be resolved before sending the unit in for repair.
Check the connections if there is no sound coming from the sub, or if the sound is faint and distorted. If the system is using an LFE connection from a home theater receiver, make sure that connection is enabled in the receiver's setup menu. If the subwoofer is using speaker wire for connection, check that the polarity is the same on both ends of the connection, and check the wire to make sure it isn't damaged.
If the sound is still distorted, change the low pass filter settings or adjust the PRO settings on the sub.
Ground loops can cause a low level 60 cycle hum in an audio system. Use a grounding plug on the subwoofer and receiver connections; these plugs are available at any hardware store. Unplug the cable line from the home theater system to see if the hum is being caused by the TV connection.
Check to see if the AC outlet is working. If it is, unplug the subwoofer and check the fuse in the subwoofer, which is located just above AC in line on the back of the subwoofer. The fuse type is listed on the back of the sub. If the power light LED light on the sub is red, or the sub appears "locked," unplug the subwoofer, let it stand for 30 seconds, then plug it back in and turn it on and see if the LCD lights green.