2020 TU8500 50" Intermittent Sound Loss

[david_h]

I have an Amazon Fire Stick 4K which I previously used without problems on my previous TV, a Panasonic. I connect the TV to my sound system via an optical cable. The sound drops out occasionally, ranging from extremely briefly to a second or so. There is no disruption to the picture but the loss of sound is really frustrating. I can sometimes go for almost a whole evening without a drop-out and then I get several. A Google search shows that this has not been uncommon for Samsung TVs in the past, although I can't find any hits relating to this (2020) model. I've tried all of the suggested fixes that I've found so far. These include:

• Disabling the Smart Hub
• Disabling Anynet+
• Switching the Amazon Fire Stick from HDMI 2 (which was eARC) to HDMI 1
• Power off and on again
• Factory reset (with all the effort of re-defining all of my settings)
• On the Fire Stick, changing the sound setting from "Best Available" to "Always Dolby Digital" and, when that made no difference, to "Stereo".

None of the above made a permanent difference.
I also ran the sound diagnostics from the Support menu- these ran clean.
I've only had this TV for about five weeks but I've already disposed of the packaging. It was a Which? Best Buy and seems to have lots of very positive reviews, but if I'd checked with Google for sound problems I certainly wouldn't have bought it. As I write this, I've been waiting for an hour for a Samsung Expert to contact me, despite the chat window saying that one should be able to support me via Chat in 15 minutes.
I then had a chat lasting over 90 minutes where Chris from Samsung Chat support, where he walked me through much of the above. He eventually said that he would book an engineer's visit, and I quote:
"Thank you for patiently waiting. Already schedule the date on Monday 16th of November 12 in the afternoon, they will be calling you before going to your place to check the availability. This your service order number xxxxxxxxxxx, that will serve as reference."
I received an email saying that Martin Dawes (the support partner) would be in touch with me. However, Chris' message stated that a date had been scheduled. At 14:00 I rang Martin Dawes who said that Chris shouldn't have given me a date or time and told me that the next available slot was on 24th November.
I'll repeat that I didn't have problems with my previous TV and I would expect this one to work just as well with the Amazon device. My sound systems shows the PCM rate except that it shows "Unlocked", indicating no input, when the sound drops out.

Any suggestions are welcome, and thank you for reading this far.

[DUMITRU79]

Is there any way to connect your TV to the sound system via HDMI ?

[david_h]

Hello, DUMITRU79- Thank you for answering. Unfortunately no, I don't have an external sound system that I can connect via HDMI. The problem occurs when playing the sound through the TV's own speaker, without the optical output defined or connected, so I think it's inherent to the TV itself.

[DUMITRU79]

Have you performed a sound diagnosis on your TV ?

[DUMITRU79]

Settings -> Support -Self diagnosis -> Start sound test ...

[david_h]

Thanks again, DUMITRU79. Yes, I performed the sound test both through the optical cable and also with the cable disconnected and the TV setting to use its own speakers. I did this prior to my chat with Samsung support, and also during the chat session. The sound test came back clean at all times.

[DUMITRU79 · Accepted solution]

I know it's frustrating , but , do you have problems with the TV's speakers on all SOURCES or just when you use as input source FIRE Stick ?

[david_h]

Frustrating, yes! Thanks again, DUMITRU79; your suggestion is certainly something that I should have thought of already. I switched the TV's source to its own set of apps and enjoyed an entire evening of uninterrupted sound, which would suggest that the fault lies with the Amazon Fire Stick. I will continue to watch using the internal apps for another evening before marking your previous response as the solution- just to be sure- and also cancel the visit from the engineer scheduled for a week's time.

(Probably OT but may be of help: Having done further searches, it appears that the 4k Fire Stick has also had sound drop-outs. One regularly suggested solution for this was to connect the Fire Stick to a 2.4GHz SSID rather than 5GHz one. Needless to say, mine is connected to the 2.4GHz SSID and the Stick suffers this problem. The TV is connected to the 5GHz SSID.)

[DUMITRU79]

Do you still have problems with the sound ?

[david_h]

Hello, DUMITRU79- thanks for getting back. 
The sound is fine when using a built-in app from the TV itself, but I still get the intermittent sound dropouts with the Amazon Fire Stick. I would normally therefore deduce that the fault is with the Amazon device, except that, when the sound drops out, the input to my sound system shows that there is no input from the TV. That is in contrast to at all other times when it shows the PCM data rate, even when no apps are active. 
I’d reiterate that this Fire Stick worked fine with my previous Panasonic TV.