I’d try unplugging both the Arc and the TV from power for at least two minutes. Plug the TV back in first, and give it a couple of minutes to finish rebooting. Double check to see if there are any software updates to be downloaded and applied. Once that’s done, plug back in the Sonos Arc and see if it is recognized.

I deleted my response as @Airgetlam is already on this. 

We likely said exactly the same thing :)

@Airgetlam (and @AjTrek1) - thanks… just went through all that but no joy, unfortunately: TV works, Sonos works, Apple TV works… but TV sound only gives TV Speakers as an option. Any idea?

Hmmm. Not the “easy” answer then. There’s 2 possibilities in my mind.

1) the TV isn’t actually sending a CEC (HDMI ARC) signal to the Sonos Arc, which means double checking all the options on the TV  and devices feeding the TV to make sure that an update to the respective systems didn’t change something without your knowledge, such as the format being sent (could be something the Sonos can’t interpret),

and 2) that something’s actually broken / fried in the Sonos so that it works with streamed music, but isn’t capable of receiving the signal. The best way to track that down is to submit a diagnostic from the controller app while it can see the Arc, and contact Sonos with that diagnostic. They’d be able to read the data and confirm whether or not there’s something wrong in the Sonos. By the way, I give this about a 1% or lower chance, it seems like the other potential is much higher.

Oh, there’s also the possibility of a “broken” HDMI cable between the TV and the Sonos. It’s certainly worth trying another cable. The ARC channel is carried on separate pins than the normal audio on HDMI, so it’s not as easy as just plugging the cable in to the TV directly, you’d end up testing another set of pin connections. 

I’m a little late to this show …

I’ll echo this, but suggest that you wait at least three minutes for the SAMSUNG to dissipate it’s stored energy.  You can speed the TV’s energy discharge by using it’s remote to give ON/OFF commands while power is removed. Obviously, the TV cannot fully power up without power, but you may notice a lazy flash of the TV status light in response to an attempt. Eventually, the stored energy will be dissipated, the status light will stop responding, and the TV is ready for the reboot. Restoring power too soon will not result in any visible error messages, but the desired reboot will not have been accomplished. It can be extremely frustrating until you figure out how long to wait, because the TV has not rebooted and any issues that could have been resolved by an actual reboot have not been cleared. (been there, done that, frustrated)

Never owned a Samsung, but lots of experience with Vizio, and I’ve always tried to leave it for 5 minutes, and go do something else, to allow the capacitors to fully discharge. But if I stand there looking at my watch, I’m always super impatient, and can barely wait 2 minutes, much less the larger, but better amount of time. 

That being said, Vizio did send out an OS update that turned back on my TV’s speakers, and turned off the optical output, which made my PLAYBAR not work….and took me a while to figure out. I assumed, incorrectly, that it was the Sonos at fault, and wasn’t looking in the right place. 

Rightio… looks like I’ll have to get stuck in some real troubleshooting here.

@buzz when I shut down/disconnected all these devices from power they were off for about 10-15mins - I just went and did something else for a bit, so I reckon that should all be ok.

@Airgetlam I’ll replace the HDMI cable; check the CEC thingie (how would a HDMI cable fail if it’s just sitting there? Power surge?); do the Sonos diagnostics - in that order.

Will advise how that goes. I appreciate the suggestions, thanks.

While this is not high on my list of probabilities, one should never expect Mother Nature to be fair. When in troubleshooting mode if one assumes that the problem must be m...] or cannot be c...], one is likely to be blindsided. Play the percentages in order to save time.

Another pea in this soup is EDID (Extended Display Identification Data). At power up or cable insertion the EDID negotiation between “Source” (ARC} and “Sink” (TV) establishes which audio and video formats each supports. (I know that this seems backward, but TV’s are normally Sink devices.) If this fails, an unsupported format may be sent across. You can force renegotiation by momentarily breaking the HDMI connection. Note that the EDID trigger is often deliberately fabricated to make its connection last as the cable is inserted into its socket. If the cable is not fully inserted the EDID negotiation may not occur.

Power surge, poor construction, metal fatigue, corrosion, all sorts of relatively rare and obscure reasons.  But rare doesn’t mean zero, so it’s worth double checking. And it’s also possible that it isn’t a failure ‘in’ the cable, but a challenge in the seating of the cable, so there’s a slight misconnect of the pins between the cable and the port. Frequently, a re-seating of the cable can help this. Again, the effort is minimal.
 

When you’re unsure about what the issue really is, looking at every potential cause, no matter how small, seems to be necessary, if only to eliminate that as a variable. 

Well, whaddayaknow: replaced the HDMI cable and it’s all up and running again.

This avoids having to try and understand the other options, which pleases me no end .

Thanks @Airgetlam and @buzz - your assistance is heaps appreciated! 

kingrolo,

Anal person that I can be, I would restore the ‘bad’ cable to confirm that it is defective.

wow, thanks man, it actually works for me.