What's going on

The Samsung S90D is a high-performance QD-OLED display packed with modern gaming and smart features. However, like many flagship models in the Samsung OLED TV line, audio pass-through via HDMI ARC or eARC can occasionally break down.

When HDMI eARC fails, the issue is almost always a digital handshake failure between the TV's Tizen OS and your soundbar or AV receiver. Instead of passing multichannel audio down HDMI Port 3, the TV either stays completely silent, defaults back to its internal speakers, or drops the signal continuously. Before assuming your TV or soundbar is broken, systematic troubleshooting usually clears up the conflict.

Symptoms people notice

• No audio output from soundbar or receiver over HDMI Port 3.
• TV speaker automatically switches back to internal speakers after rebooting.
• Audio cuts in and out every few seconds while playing spatial audio formats like Dolby Atmos.
• Volume control via the Samsung remote doesn't change soundbar levels.
• Screen displays an 'eARC device connected' notification, but no sound plays.
• Significant audio lag or lip-sync errors when using external devices like Apple TV or Xbox.

Likely causes

1. CEC Handshake Lockup: Digital lockup in memory prevents the TV and soundbar from identifying each other over HDMI-CEC.
2. Anynet+ Disabled: The underlying HDMI-CEC framework is disabled in Samsung's settings.
3. Incorrect Port / Cable Bottleneck: The HDMI lead is in the wrong port or lacks the bandwidth necessary for high-bitrate uncompressed audio.
4. Audio Format Mismatches: Tizen OS audio format settings are attempting to send an unsupported stream format to the soundbar.
5. Interference from Peripheral Devices: Another device plugged into HDMI 1, 2, or 4 is sending conflicting CEC control signals.
6. Software Bugs: Outdated firmware on either the Samsung display or the connected receiver.
7. Main Board Port Failure: Hardware damage to the HDMI controller on the S90D main board.

Quick checks first

Start with the simplest fixes before digging into complex menus:

• Check the label on the back: Ensure the HDMI cable is firmly seated into HDMI Port 3. Ports 1, 2, and 4 do not support ARC/eARC functionality.
• Power cycle the TV remote: Press and hold the Power button on your Samsung SolarCell remote until the TV turns off and the Samsung logo re-appears to soft-reboot Tizen OS.
• Test a short cable: Try a known-working Ultra High Speed (HDMI 2.1) cable shorter than 6 feet. Long, cheap, or damaged HDMI lines lead to handshake dropouts.
• Check soundbar input mode: Verify your soundbar is set to 'eARC/ARC' or 'D.IN' mode, not Optical, Bluetooth, or AUX.

When it's a real hardware fault

If you have performed cold reboots, replaced cables, tested different soundbars, and still get zero audio response on HDMI 3, you may be dealing with a hardware-level defect. Physical damage to the port's solder joints, electrostatic discharge (ESD) spikes, or a failing HDMI receiver IC on the main board will prevent signal transport even if Tizen OS detects a cable is plugged in.

If optical output or internal speakers work fine but HDMI 3 remains non-functional with every audio system you connect, the TV's main board likely needs physical replacement. Browse our general TV problems hub for broader hardware failure context.

Soft resets vs board/panel work

Most eARC handshake glitches on the S90D are soft failures. A soft reset involves clearing power from the capacitors and resetting the CEC network. You can do this by unplugging the power cables from both the TV and soundbar for a full minute, disconnecting the HDMI cable, then restoring power before reconnecting the HDMI cable.

Replacing internal components like the main logic board requires opening the ultra-thin OLED cabinet. Due to extreme panel fragility and live power supply voltages, internal board swapping is not a recommended DIY project for most owners. Focus fully on settings, cables, and resets first.

Next steps

1. Run a full power cycle (unplug all power and HDMI cables for 60 seconds).
2. Double-check that Anynet+ is active in Settings > Connection > External Device Manager.
3. Set Audio Output to Pass-Through and eARC Mode to Auto under Sound settings.
4. Swap in a certified 48Gbps HDMI cable directly into Port 3.
5. Update both your TV and soundbar to their latest firmware releases.

If you are considering upgrading your audio gear or looking into secondary displays, check out our in-depth hardware reviews in our reviews hub.