TCL QM7 QLED Mini-LED TV ARC or eARC soundbar audio is not working

The checks in more detail

Plugging the soundbar into any other port makes it an input instead of an output. Turn on HDMI-CEC in the TV's settings, usually named Control other devices or HDMI control, because the handshake needs it, and turn on the matching setting on the soundbar. Then set the output. In Settings, Display and sound, Audio, choose the soundbar or HDMI eARC as the output, and set the digital output format to Auto if the soundbar supports surround and eARC, or to PCM if you want the safest stereo.

Dolby Atmos over a streaming app needs eARC on both devices and the right setting in the app; a soundbar that supports only ARC will play compressed Dolby Digital instead. If you hear nothing, check that the soundbar's input is on ARC or TV, and its volume is up. If the TV remote does not control the soundbar's volume, CEC is the usual culprit; check both settings and restart both devices. Dropouts and clicks suggest a poor cable, so try another.

Power cycle by turning off the TV and the soundbar, unplugging both for a minute and powering the soundbar first. Update the TV in Settings, System, About and the soundbar's firmware. If lip sync is wrong, use the TV's audio delay setting or the soundbar's own. If a game console is connected to the soundbar and then to the TV, the chain can cause problems; connect the console to the TV directly. Compare with the optical output, if both have it, to check the soundbar.

If eARC never works with a good cable, the right port and CEC on, contact TCL with the model number and the soundbar's model number. The QM7 has an HDMI port marked eARC, and it is easy to plug a soundbar into the wrong one, so look at the labels on the side or back panel and use the one marked eARC and ARC. In the sound settings, set the digital output to Auto or to Pass-through depending on what the soundbar accepts, since a bar that cannot decode Dolby Atmos over a bitstream can fall silent when the TV sends it.

A High-Speed HDMI cable from an old setup may not carry eARC reliably; an Ultra High Speed cable fixes many dropouts. Turn on HDMI-CEC on the TV (TCL's name for it is T-Link) and on the soundbar so that the volume buttons on the TV remote control the bar. If sound works from the TV's apps but not from a connected console, check the console's own audio output setting rather than the TV's.

The TCL QM7 runs Google TV, and its Settings, Display and Sound, Audio, menu names the output device, so check that HDMI eARC is the selected output rather than the built-in speakers or Bluetooth. Updating the TV's software from Settings, System, Software update matters, since TCL has issued fixes for HDMI behavior. A soundbar that supports only ARC and not eARC works fine with the same port but at lower quality formats, so a bitstream setting of Dolby Digital rather than Atmos is the usual fix when sound drops.

Unplug both devices for a minute to clear a stuck handshake. On the QM7, Settings, Display and Sound, Audio lists the output device, and if it says Speakers the soundbar is not in use even though the cable is fitted. Select the eARC output and, if the option is grayed out, turn on HDMI-CEC in the HDMI settings so that the TV and the bar can negotiate. Some soundbars show an eARC light, and if it stays off, swap the cable.