That's often the culprit.
However I don't see your model listed anywhere on the TCL support site. Could you double check that?
We have a TCL LED smart tv (E5800FS) and have just hooked it up via optical cable to our LG blueray/DVD home theatre system (LHB755W).
We can play movies from a USB connected passport through the tv and get picture and surround sound through the LG system. ...but when we try to watch free to air tv the signal (picture and sound) disappears as soon as we turn the LG system on .....back off again the signal picture and sound reappears on the TCL tv .....any ideas as to how we can play audio from free to air tv through our surround sound system??? Or why the tv signal stops when we turn the LG system on?? Help!!!