Does your TV have the latest firmware installed? Try unplugging the TV and Arc from power for about a minute. Also try setting Digital Audio Out to Auto 1 or Auto 2, not PCM.

Hi GuitarSuperstar

I can confirm the software is up to date, ive just ran the update software function again to make sure.

Kernel Version 4.9.125 #1 Wed Feb 3 2021

Ive tried all settings, on the Digital Audio Out too and some even lose the sound completely.

Just unplugged everything too and hasn't fixed it.

Is that the Sony firmware v6.0466? (24th Feb)

https://www.sony.co.uk/electronics/support/lcd-tvs-android-xh90xx_x90xxh_x91xxh_xh92xx-series/kd-65xh9005/software/00258726

Hi Ken_griffiths

Software version: PKG6.0466.0059EUA

So yes it looks like the firmware you suggested.

In that case, if you perhaps ‘temporarily’ disconnect your other hdmi connected TV peripherals, see if that stops the dropout issue. If it does, then that may suggest one of your connected devices are using HDMI-CEC too and perhaps stealing the focus away from the Arc.
 

You can try discovering which device is responsible by adding each device back to the TV, one by one… if you can go onto discover the device and are able/okay with switching off it’s HDMI-CEC feature then I would do that and all being well the issue will go away. 
 

Note some devices do not allow the switching off their HDMI-CEC control in which case you could use a CEC-Less adapter instead, like the one shown in this link:

https://www.amazon.com/Lindy-HDMI-Adapter-Female-41232/dp/B00DL48KVI/ref=sr_1_1

Hi Ken_Griffiths

Still having issues and extremely disappointed this is happening with a £800 soundbar.

There are only 2 devices connected the xbox and the sonos arc. The xbox is off whenever we have issues with sound dropping when watching purely tv and using the tv apps.

Is there a chance the soundbar could be going into a sleep mode for a couple seconds 10-20 seco after a set time period?

kinger251285,

Did you try disconnecting the other devices, just temporarily as mentioned, and did that solve the matter for you? Just trying to establish if the HDMI-CEC protocol is at the centre of your issue? You are best to uncable the products whilst testing.

So the issue still persists and sonos support have been beyond useless.

Furthermore the arc has now started producing loud massive bangs. Happened 3 times so far, managed to do a diagnostic immediately after the last 2. Again all 3 have been random whilst using the TV alone. 

Reported to sonos support and again beyond useless:

Support: “Sir can you video record this?”

Me: “Are you expecting me to record for the entire time and every time im using the arc? Are you expecting me to purchase a new device to record this?”

Support: “We really cannot do anything without video evidence”

Me: “Can you please explain to me how you would expect me to record a random loud massive bang from the soundbar?”

Support: “I cannot because i do not know your setup but the video would be really helpful”

Me: Bangs Head against wall yet again.

Sonos have been beyond frustrating and look like they require evidence to ensure im not lying. Why would i lie, i just want a working system. 

*****UPDATE ******

So thought id check back in and give an update in case it helps anyone else. 

The issue on the TV still persists, the sound cuts out randomly when watching apps (Disney+, Netflix etc), when watching Live TV and directly through the DVB Tuner. 

Further more the Xbox Series X has sound cutting out every 0.5 seconds when set to bitstream, dolby atmos and 4K@120hz.  I change the xbox back to 4K@60Hz then bitstream & dolby atmos works fine. Another issue being that dolby vision only works at 4K@60Hz due to the TV's restrictions. There is an enhanced setting within the tv HDMI output for dolby vision but both 4K@120hz and dolby vision do not work. 

This has been found out by further experimentation and more people across the internet doing research and putting up videos and articles regarding this TV, soundbars and the xbox series x. 

The conclusion being a poorly configured eARC HDMI. All fixable according to the experts via a firmware update. Which is great but frustrating this has not happened yet on a TV that was advertised specifically as 'Next Gen Gaming Ready'.

I am now in the process with Sony Customer services to sort a fix or return the TV and purchase something that is advertised correctly and works.