To troubleshoot a connection issue between a Smart TV and home theater system, follow these steps:

1. Check all cables and connections: Make sure the power cords are connected, and that the HDMI, coaxial, or any other cables that are being used for connection are firmly attached.
   
2. Test the connections: Try connecting a different device to the home theater system, like a Blu-Ray player, to check that there are no issues with the hardware.
   
3. Restart the devices: Going through a simple restart cycle often fixes most issues. Disconnect the power cables from both the Smart TV and the home theater system, wait for a few minutes, then reconnect and turn them on.
   
4. Check the settings: Make sure sound is turned on in both devices and that both are set to output audio through the same source. On the Smart TV, verify the HDMI connection is the default audio output.
   
5. Update the Smart TV: Check for any available updates for the Smart TV firmware. Similar to other devices, updates may contain bug fixes and other improvements, which might resolve the issue.