Recently purchased this tv. Connected it to my Sony sound system and xfinity cable box thru an hdmi cable, as there were limited instructions in the “manual” provided. Initial problem was that the tv sound would not play thru my sound system and when I switched from my cable feed to a roku streaming channel, I got sound from both cable channel and Roku channel. Called TCL support and after an hour and a half and going thru all of their basic trouble shooting, still had the problem. On the second call, the agent asked if I had a fiber optic cable connected from tv to sound system as she said that was required, but there’s nothing in the paper manual saying that. I said no and went out to buy one. After connecting the fiber optic cable, I still had the dual, sound problem. I set the tv sound to off, but this didn’t solve my problem. Called a third time and the agent I got Immediately told me to leave the optical cable connection from the Roku tv to the sound system in place and take the hdmi cable going from my cable to my sound system and plug it into an hdmi port on my tv. That immediately solved my problem. He then Said I could remove the hdmi connection from my tv to sound system. Everything still worked. I then moved the blu-Ray hdmi cable from the sound system to an hdmi port on the Roku tv and was able to now hear the sound from the blu-Ray thru the tv, into my sound system. I am now very pleased with how everything works. Clearly TCLs support database is not adequate and the quality of the service still depends on the agent. I am bothered by the fact that the first agent didn’t immediately know what to do, when I told him the symptoms.
Thank you so much for posting your experience! While our experience wasn’t the same, reading your post helped us resolve the issue. We had sound watching tv but streaming still had the tv sound. We had the optical cable connected from the cable box to the sound bar. After switching the optical cable from the tv to the soundbar we get sound watching tv and watching streaming channels. Thank you again!