I recently bought a brand new the KD-55A85 just over a month ago. I also have Sky Q UHD installed and plugged into the tv via HDMI. The only other device I have plugged in is a 3rd generation Apple TV via HDMI also. I do not have any sound bar or sound devices connected. 

The issue I am having is with sound delay which creeps in to the video within 5-10 minutes of watching the tv. The sound and video was perfectly fine in the morning when I came back to put the tv on in the afternoon, after a few minutes of watching the tv I started realising the sound was delayed from the video. As time went on it got worse and worse. If I restart the TV or the Sky Q box then it’s ok to begin with and then slowly the sound starts to delay again. This is the case on both the Sky Q box and the Apple TV. However, if I watch something via the Android TV apps then the sound is perfectly fine.

I have adjusted the sound settings and HDMI sound output on the Sky Q box settings, and also adjusted the sound settings on the TV as well, but have not been successful with fixing the sound delay. I have also changed my HDMI cables and that also has not resolved the issue. I connected the Sky mini box to the TV and that also produced the sound delay. 

Could someone please provide some potential solutions or a fix. I have got a Sky engineer coming out to check the Sky connections, box and dish but I have this nagging feeling the issue is with the tv and specifically the HDMI connections. 

Thanks.