no sounds output on Sony KDL-40EX720

Do you have Control for HDMI/Bravia Sync (CEC) enabled on your TV? Do you have any other devices connected to your TV? Unplug any devices from your TV before your start the TV Setup process in the Sonos app.

In HDMI Set-up, Control for HDMI is on. I don’t have an enable Bravia Sync option. Yesterday, in the controllable HDMI system list, Sonos Arc was listed. Today when I turned the TV., it said something about a communication failure and disabling/disconnecting something. Since then, No more Sonos Arc in the list of devices.

I did disconnect everything.

When I plug the soundbar in another HDMI plus, it shows a screen saving pattern, the soundbar plays the Sonos radio without issues. I wonder if something is fried in my HDMI arc port...

Control for HDMI is the same as Bravia Sync.

Do you have any other devices connected to your TV?

OK, I noticed something interesting that escaped my attention yesterday: while the Sonos Arc is detected in the device list, it is never on HDMI port 1 (the Arc port). It is detected after I connect it to another HDMI port and when I then change the cable to HDMI 1, it is again detected but under the previous port it was connected to.

I then did a factory reset, reconnected the HDMI cable, I got the message about a sound system being active, still no sound and the device is still listed under HDMI 2 while it is plugged into HDMI 1.

Does this give any clue about what is going on?

No other devices plugged in while I was doing this (except the antenna cable).

What you described is very odd. There might be something wrong with your TV.

Try this:

1. Unplug your TV and Arc from power for about a minute.
2. Plug them both back in and turn on your TV.
3. Set “Speakers” in your TV settings to “Audio System”.
4. Set “Control for HDMI” in your TV settings to “On”.
5. Set “HDMI/DVI Audio Source” in your TV settings to “HDMI Audio”.
6. Run “TV Setup” under the Arc settings in the Sonos app.
7. Follow the instructions in the app and plug the HDMI cable in HDMI 1 on your TV.

If this fails, you may just have to use the HDMI to optical adaptor.

Might not hurt to also check for updates from Sony for the TV set.

The TV has the latest software and the optical cable does not fit in the optical socket of the TV, it won’t get completely inside. Are there different format for optical connections?

@GuitarSuperstar, I did all that and the TV says “no device detected” and the Sonos App says Bravia Sync not connected.

Now I remember I had an issue with my set top box (Optus) after a lightening strike that also fried an ethernet port on another device. I had my set top box replaced thinking it was the box that was fried, and the box worked fine after that (not sure in what port though, that was 5 years ago).

Could it be that the HDMI input of the HDMI ARC port is working but not the HDMI ARC out? In other words, could the ARC functionality be fried while the rest works fine on HDMI 1?

Yes, it is very possible that the lightning strike damaged the HDMI ports of your TV. Were you able to get the optical adaptor connected?

I tried every angle, I can see a red light. There was initially some kind of membrane or cover but it came off

Can you post a photo of the optical port on your TV?

OK, I was looking for a cap on the TV socket but there was one on the cable… I was able to connect it through optical.

It said this was for initial setup only on the box. What do I do now? do I disconnect it or leave the optical connection on ans the ongoing connection? 

Turn off “Control for HDMI” on your TV.

Set “HDMI/DVI Audio Source” in your TV settings to “Auto”.

Run “TV Setup” in the Sonos app and follow the instructions and connect the Arc to your TV with the optical adaptor.

I have done that and it is connected, so whats next? The box for the optical adapter says it's only for the initial setup. It is not clear whether i should now try the hdmi arc port.

Keep the Arc connected to the TV with the optical adaptor. Don’t use the HDMI port. Do you hear any audio from the Arc?

yes, it’s working fine on Optical, but the app said it would not support Atmos on Optical. Some sound is better than no sound, but part of the reason I got the Sonos over the Bose 700 was the support for Atmos...

Even if the Arc worked with your TV’s HDMI port, you still wouldn’t be able to get Dolby Atmos audio with your older TV.

According to this link, I could: https://support.sonos.com/s/article/4844?language=en_US

Your TV is from 2011. I’m 99.99% sure it won’t pass through Dolby Atmos audio from any internal apps or external devices.

If your HDMI ARC port actually worked, I would have recommended getting the HDFury Arcana if you want Dolby Atmos audio using your current TV. https://hdfury.com/product/4k-arcana-18gbps/

Having checked the manual for this TV, I concur, there is only mention of the ARC channel being capable of Dolby Digital, and not Dolby Digital Plus, required for Atmos. 

Thank you all for the very helpful comments! Special thanks to GuitarSuperStar for guiding me step by step!

Actually, KDL-40EX720 does support Dolby Digital Plus according to this page:  https://www.sony.co.uk/electronics/support/televisions-projectors-lcd-tvs/kdl-40ex720/specifications

But since my ARC port is half-fried, it doesn’t make a difference to my dilemma...

Just one last question guys, I looked at buying a new TV to match the capabilities of the soundbar and found this one that seems like a good option. The only issue is that it says in the footnotes that eArc is available through a future update (search for “eArc” and click on footnote 3). Does anyone know if this TV already has that update or if it’s still in the making? I am totally out of my depth with modern hifi, so I can’t tell...

https://www.sony-asia.com/electronics/support/televisions-projectors-lcd-tvs-android-/kd-55x9000h/specifications#rfn-3

I believe the Sony X9000H is the same model as the X900H. eARC is available on the X900H. You may want to contact Sony to confirm this. One other note: Some X900H users have experienced some audio lag and audio cutting out with the Arc. You can search for “X900H” in these forums to read more about it.