Samsung QN90B Neo QLED TV has picture but no sound

The checks in more detail

Start with the basics. Check the volume and the mute, and turn the volume up with the remote, since a muted TV or a volume at zero is the commonest cause. Look at the on-screen volume bar. Open Settings, Sound, Sound Output and choose TV Speaker, to see whether the built-in speakers work; if they do, the fault is with the external device you had selected. If you use a soundbar, choose it by name, and make sure that it is on, set to the right input and not muted.

Check Bluetooth: a Bluetooth speaker or headphones that are still paired can take the sound from the TV speakers, so disconnect them in the Bluetooth device list. Then the connections. For an HDMI eARC or ARC soundbar, use the port marked eARC or ARC on the One Connect style panel or on the TV, with a high-speed cable, and enable the soundbar's HDMI-CEC, called Anynet+ on Samsung. If an optical cable is used, check that it is fully seated and that the sound output matches. Check the source: if the sound is missing in one app, try another input;

if it is missing on an HDMI device, set the device's audio to PCM or Dolby Digital, and check the TV's Expert Settings, Audio Format, to match. Run the Sound Test in Settings, Support, Device Care, Self Diagnosis, Sound Test; if the test plays, the TV is fine and the source or the external device is at fault. Restart the TV by unplugging it for a minute, and update the software. If the Sound Test is silent with the TV Speaker selected, contact Samsung with the model number, since the speaker or the board may need service.