Diagnosis
This issue is typically caused by the LG SP7Y's "Auto Device Detection" (ADD) feature. The soundbar is designed to automatically switch inputs when it detects a signal from another source (like an optical cable or a secondary HDMI device). If your TV is sending intermittent signals or if another device is plugged into the soundbar, the system misinterprets this as a request to switch sources, overriding your HDMI ARC connection.
How to Fix It
To stop the soundbar from automatically jumping inputs, you must disable the Auto Device Detection feature:
- Ensure the soundbar is powered on.
- Using the LG soundbar remote, locate the F (Function) button.
- Press and hold the F button for approximately 5 seconds.
- Watch the front LED display; it should flash and then display "A.D.D. OFF".
- The soundbar will now remain on the manually selected input regardless of other incoming signals.
If That Didn't Work
If the switching persists, the problem likely lies with the HDMI-CEC (Consumer Electronics Control) handshake between your TV and the soundbar:
- Check Cable Integrity: Ensure you are using a High-Speed HDMI cable (version 2.0 or higher) specifically plugged into the HDMI (ARC) port on both the TV and the soundbar. A faulty cable can cause "ghost" signals that trigger input swaps.
- TV Settings: Access your TV's settings menu and look for SIMPLINK (LG TVs) or HDMI-CEC. Toggle this setting OFF and then back ON to reset the handshake.
- Disable Other Inputs: If you have an optical cable connected simultaneously with the HDMI cable, remove the optical cable, as this often triggers the ADD feature.
Heads Up
Disabling Auto Device Detection means the soundbar will no longer "hunt" for the active source. If you ever switch to a different input manually, you will now be responsible for switching it back to HDMI using the remote; the system will no longer do this automatically.