Can anyone help? I keep hearing a 3 second high pitched beep but can't quite tell where it is coming from n our lounge where our home theatre system is, i.e. LED TV, receiver, speakers, blu ray player, modulator, router, Foxtel box and modem. There are a couple of cable connector boxes behind the system also. I thought it was our fire detectors but I took out the batteries and I could still hear this beep lasting about 3 seconds every 15 minutes. I unplugged the power for the TV and waited 15 minutes - I could still hear the beep. I unplugged the router - still could hear the beep. I unplugged the Foxtel box - still could hear the beep. I unplugged the receiver - still heard this annoying beep.
John in Canberra, Australia
one by one start unplugging the devices. if you still hear the beep you know its not that device. (this is what you were doing)
if you have worked through and have all devices unplugged and still hear the beep, then its not coming from those devices in your home theater.
it sounds like a smoke detector. make sure you didnt miss one. it could also be coming from the panel your internet provider installed (if any) which sometimes have a battery backup in them. also, it could be coming from a UPS battery backup. generally, check anything with a battery-backup.