Have you enabled simplink on the TV and switched off eARC? 

Ensure TV Autoplay is set to ‘ON’ in the Amp Room settings in the S2 App and that your HDMI cable has HEAC support (HDMI 1.4+).

Hi Ken

Thanks for your reply.

LG CX TV = Simplink (CEC) is on. eARC is off. Digital sound set to PCM. DTV to Dolby Digital.

SONOS 2 App = TV Autoplay is ON.

I have tried various good and new HDMI cables.

I even purchased a Sonos optical to HDMI Adaptor, optical from TV did not work to Amp.

If I select HDMI-2 on the TV, I see the SONOS image (black and white stripes).

On the SONOS 2 App, “TV Setup”  “Test Connection” fails to connect to TV.

I was hoping that later updated to TV and Amp may fix this, but past few months no luck.

Thanks. (Melbourne, Australia).

It’s concerning that the optical and HDMI connections are both not ‘consistently’ working particularly following the power outage. Have you tried the setup with another TV (if you have one?) or seeing if the TV sound-out works with another Receiver (if you have one?).

Do you have any other devices connected to the TV? Is Auto Device Detection turned on and Auto Power Sync turned off?

Hi

Thanks for the input - it is appreciated.

Re “Auto Device Detection turned on” = yes; and “Auto Power Sync turned off” = I switched it off.

Re  “setup with another TV”, yes, for two years I had a Samsung 4k Smart TV connected to the Sonos Amp via ARC. (Before I purchased this new LG CX 65).

Today I went to purchase a new HDMI Cable (specifically stated 8K, CEC, ARC and Ethernet compatible, so I assume it is HDMI 2.0 or 2.1).

Connected from LG CX TV HDMI-2-ARC Port to Sonos AMP. On TV, select audio to ARC. No sound from Sonos Amp.

Tried iPhone Sonos S2 App (V13.1) to connect to TV, still failed.

So, still no further progress...

Thanks again...

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Try disconnecting the Amp from the TV and unplugging the Amp and TV from power for a couple of minutes. Then plug them both back in, make sure CEC is enabled on your TV, and run the TV Setup process. Connect the Amp to the TV when the Sonos app instructs you to.

Hi GS

Many thanks for your considered reply and process.

I tried that (twice). no go. Same result.

I also switched off main house power, to simulate a suburb outage a few days ago. On that occasion that evening when we switched the tv on, the ARC (autodetected) worked ! Until we switched tv off, and next time I had to manually select Internal TV Speakers again.

(OK, I have 4- hr UPS for server, nas, network switch and cctv security systems.).

When I / we find this, i suspect it will be one stupid setting somewhere !

< I am also 70’music fan; amongst many is Pink Floyd Pulse Concert London circa 1996 ]

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HDMI-2 on the TV = Sonos image..

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Both TV and SONOS are wired Ethernet to the network switch.

The fact the Amp works (and presumably still works with the Samsung TV) seems to point to the issue as being with the LG TV - have you perhaps considered factory resetting the LG TV? I know on the older LG C9 TV there is a hidden menu for A/V reset aswell, by pressing the mute on/off three times and press A/V reset, but not sure if the feature is available on the CX TV.

Hi Ken

The “mute on/off three times and press A/V reset” works on the LG CX as well ! Thank you..

I did the reset, plus the connect sequence via the App, but no go.

Dunno then, you may possibly have a hardware fault somewhere, either the TV, or Amp and if Amp was/is working with the Samsung, it seems like it’s the TV. Possibly the power outage was the cause, but who can say? - I would contact both Sonos support and LG support desks. With Sonos, also submit a system diagnostic report and give them the reference number and ask them to take a look to see if there are any obvious signs of a fault. You can contact Sonos support via this LINK 

I think the LG support option maybe available to you via this link:

https://www.lg.com/au/support

Hi Ken and GS

Thank you both for your support.

Here is a happy outcome:

The SONOS "automated" Support prompt guided me to the point where it said "Please disconnect all HDMI devices except the Beam from your TV. Unplug your TV from power for 1 minute. Plug your TV back in and test with a TV program."
I did this an the TV switched on and went direct to ARC Audio to the Sonos Amp!.
I switched the TV off and on again to check, and it still worked.

The trick seemed to be to disconnect all other HDMI inputs from the TV (used the “free-to-air TV input to get program, that test).

Any last comments?

Ah that’s great news, I’m surprised that GS’s earlier post, where he mentioned the below didn’t resolve it, but the important thing, is that it’s now working.

‘Try disconnecting the Amp from the TV and unplugging the Amp and TV from power for a couple of minutes. Then plug them both back in, make sure CEC is enabled on your TV, and run the TV Setup process. Connect the Amp to the TV when the Sonos app instructs you to.’

I guess it might help the situation, if you are able to switch off HDMI-CEC on your other connected peripherals, but I usually leave those on myself for universal control by the LG’s Magic remote.

Anyhow all is well that ends well.

That’s why the first question I asked was:

“Do you have any other devices connected to the TV?”

I assumed since you didn’t answer the question that the answer was “no”. That’s why it’s bad to make assumptions. Glad you got it working.

Thank you for the guidance - it is really appreciated.

One last note:

The TV still did not return automaticall and reliably to ARC audio to the Sonos Amp after switching off and later on again.

Had to do the “remove HDMI 1” (Foxtel Pay-TV Box) and re-start, to get it active, each time.

Then, I found this setting in the LG CX TV Menu “Quick Start”.

Switching this on seems to let the TV connect to the Sonos every time.

I will track the results over next few days...