soundbar says 'no signal' when my tv is on and connected via hdmi arc. how do i fix it?

Diagnosis

The "No Signal" message on the LG SP7Y indicates a failure in the HDMI-CEC (Consumer Electronics Control) handshake process. For a soundbar to receive audio via ARC (Audio Return Channel), both the TV and the soundbar must agree on a communication protocol. If the TV is sending a signal that the SP7Y doesn't recognize, or if the TV's output is still routed to the internal speakers, the soundbar remains in a standby state and displays "No Signal" because it isn't receiving the active trigger to switch to the HDMI input. This is frequently caused by a "handshake hang," where the EDID (Extended Display Identification Data) information is corrupted or mismatched. This happens often after a firmware update or a power surge. You can confirm this is a handshake issue if the soundbar works via Optical cable but fails via HDMI, or if the soundbar powers on but refuses to switch from "Optical" or "Bluetooth" to "HDMI" even when manually toggled via the remote.

How to Fix It

To resolve the handshake failure and force the LG SP7Y to recognize the ARC signal, follow these precise steps:

1. Hard Power Reset: Turn off both the TV and the soundbar. Unplug the power cables for both devices from the wall outlet. Disconnect the HDMI cable from both the TV's HDMI (ARC) port and the soundbar's HDMI OUT (ARC) port. Wait exactly 60 seconds to allow the capacitors to discharge.
2. Physical Connection: Plug the HDMI cable back into the TV's designated HDMI ARC port (usually HDMI 2 or 3, labeled clearly on the back panel) and then into the LG SP7Y's HDMI OUT port. Ensure the cable is seated firmly; a loose connection often causes the "No Signal" loop.
3. Power Sequence: Plug the TV into the wall first and power it on. Once the TV is fully booted to the home screen, plug in the LG SP7Y and power it on. This ensures the TV is ready to "handshake" as the master device.
4. TV Audio Configuration: Navigate to the TV's Settings > Sound > Sound Out. Change the selection from "Internal Speakers" to "HDMI ARC." If your TV has a "Digital Output Format" setting, change it from "Auto" to "Pass Through" or "PCM" to test the connection.
5. Soundbar Input Selection: Using the SP7Y remote, press the F (Function) button repeatedly until the display explicitly reads "HDMI."

If That Didn't Work

• Swap the HDMI Cable: The SP7Y requires a High-Speed HDMI cable with ARC support. If you are using an older cable (HDMI 1.2 or lower), the ARC pinout may be missing. Replace the cable with a certified HDMI 2.0 or 2.1 cable. Avoid cables longer than 15 feet, as signal degradation can cause the "No Signal" error on LG soundbars.
• Toggle SIMPLINK/CEC: On your TV settings, find the HDMI-CEC option (LG TVs call this "SIMPLINK," Samsung calls it "Anynet+," Sony calls it "Bravia Sync"). Turn this setting OFF, wait 10 seconds, and turn it back ON. This refreshes the CEC table and often forces the soundbar to wake up.
• Firmware Update via USB: If the issue persists, the SP7Y may have a bugged firmware version. Download the latest firmware from LG's support site onto a FAT32 formatted USB drive. Insert it into the USB port on the back of the soundbar and keep it powered on until the display indicates the update is complete.
• Test with Optical: Connect a Toslink Optical cable from the TV to the soundbar. If audio works via Optical but not HDMI, the HDMI ARC port on either the TV or the soundbar may have a hardware failure (blown capacitor or bent pin).

Heads Up

• Port Precision: Ensure you are using the HDMI OUT (ARC) port on the soundbar. Plugging into a non-ARC port will result in a permanent "No Signal" message.
• Cable Quality: Always use "High Speed with Ethernet" cables. Cheap, non-branded cables often lack the necessary shielding for the ARC return channel, leading to intermittent audio drops.
• Avoid Power Strips: If possible, plug the soundbar directly into a wall outlet. Some low-quality power strips cause voltage drops that can disrupt the HDMI-CEC handshake during startup.
• TV Compatibility: Ensure your TV actually supports ARC. If the TV is older and doesn't have an ARC-labeled port, you must use the Optical cable instead of HDMI.