The discontinued SWF-BR100 subwoofer system is now at an age where dust might have built up on the connections of the UWT-BR100 wireless transceiver "dongle". Specifically at each end of the short cable that connects between the TV's headphone socket and dongle itself. The result is a constant, low volume, high pitched whine from the subwoofer whenever it is powered up, that is whenever the green light on the end of the dongle is lit.
If you have this problem the simple solution almost certainly is just to clean the two jacks at each end of the short cable and then press them fully back in to ensure they are connecting properly. If that does not work then consider covering the male jacks with a very thin layer of conducting lubricant grease based on either graphite or copper. Also, the dongle itself is quite heavy and over time can easily start drooping down at an angle from the USB port, with a similar high pitched whine resulting. It is easy to prevent this with layers of double-sided sticky tape placed on the dongle and attached to the adjacent face of the TV. To fill the gap between the dongle and the TV it will take 2 or maybe 3 layers of the tape. That ensures the dongle remains at the correct angle to the USB port. Press firmly in position and that should provide a good fix.
Hope these possible solutions help.
