What's going on

The Samsung QN90C is a flagship TV in the Samsung Neo QLED lineup, featuring HDMI 2.1 across its ports and dedicated eARC (Enhanced Audio Return Channel) capability on HDMI Port 3. However, communication between Tizen OS and external audio receivers or soundbars can frequently stall out.

When HDMI eARC breaks down, the TV and audio system fail to complete their initial handshake. This leaves your soundbar completely silent, forces the QN90C to fall back to its internal speakers, or produces choppy audio during surround sound playback.

Symptoms people notice

• The soundbar turns on with the TV, but no sound plays.
• The audio output setting flip-flops repeatedly between Receiver (HDMI) and TV Speaker.
• Sound cuts out every few minutes, requiring you to toggle the soundbar power.
• The TV displays an error stating Anynet+ device search failed.
• Audio plays fine on YouTube apps but goes silent on streaming apps outputting multi-channel surround sound.

Likely causes

Most eARC problems on Samsung TVs stem from software handshake glitches rather than blown hardware components. Typical culprits include:

1. Anynet+ (HDMI-CEC) Glitches: Tizen OS occasionally loses track of active CEC devices after app updates or standby sleep cycles.
2. Wrong HDMI Port: On the QN90C, only HDMI 3 handles eARC/ARC traffic. Plugging your soundbar into HDMI 1, 2, or 4 results in zero return audio.
3. Cable Bandwidth Restrictions: Older HDMI cables (18Gbps or lower) often drop audio packets when uncompressed eARC data flows back from the TV.
4. Audio Format Mismatch: Setting the digital output to forced Bitstream or incorrect PCM configurations can cause receivers to reject the signal.

Quick checks first

Before taking drastic measures, execute this software reset sequence:

• Force Restart the TV: Hold the Power button on your Samsung Smart Remote for 5 seconds until the TV turns off and the Neo QLED boot logo reappears.
• Check Cable Seating: Ensure the HDMI cable is completely seated on both ends. HDMI cables plugged into tight wall mounts can back out slightly over time.
• Update TV Software: Go to Settings > Support > Software Update and install any pending updates. Firmware updates frequently patch CEC stability issues.
• Disconnect Other HDMI Devices: Unplug game consoles or media streaming sticks temporarily. A malfunctioning secondary CEC device on HDMI 1 or 2 can sink the CEC bus for the entire TV.

When it's a real hardware fault

If you have performed cold reboots, swapped cables for certified 48Gbps lines, and tested your soundbar on another display without success, the hardware on the QN90C may be compromised:

• Physical Port Damage: Pins inside HDMI Port 3 can bend or snap if tension was pulled on the cable.
• Main Board HDMI Control IC Failure: Power surges through the HDMI line can fry the CEC/eARC control chip on the main board while leaving picture processing intact.

If the main board's HDMI ARC circuit is burned out, your immediate workaround is connecting an Optical (Toslink) cable from the TV's Optical Out port to your soundbar. Note that Optical does not support Dolby Atmos or volume control via the TV remote, but it restores stable sound immediately.

Soft resets vs board/panel work

Over 80% of HDMI ARC failures on Neo QLED models are resolved with cold resets, cable upgrades, or settings tweaks. You do not need to open the TV casing or replace boards for standard handshake bugs.

Replacing a Samsung main board requires removing the entire back panel and handling sensitive ribbon connectors. Never open the TV while connected to power, and leave internal board replacements for qualified hardware specialists if soft troubleshooting fails.

Next steps

If your audio issues extend beyond HDMI ARC into video blackouts or mainboard instability, browse our full guide on TV problems and fixes. For details on companion gear and soundbar compatibility reviews, explore our dedicated reviews hub.