Samsung “The Frame” Smart TV BT/Wifi issues

[NizNoz]

Hi people! Newbie here, so be kind 

I bought a used “The Frame” TV that was advertised as “not working”. The owner said “someone” told him to replace the “smart box”. The Frame TV features a slim profile allowing it to be mounted to the wall with little gap. This is enabled by having some of the hardware contained in a separate box, which is connected to the TV itself by an fibre optic cable.

On turning on the TV it seemed the issue was that of Bluetooth connectivity. It wasn’t connecting to the remote (combination BT and IR controller). Only the buttons controlling power (which are IR functions) worked, and this led to the TV repeatedly rebooting. A simple fix was using a regular, universal remote which could control some of the regular functions with IR. Later, In this way I was able to find another issue.  The wifi wasn’t working consistently either. In fact, the more I tinkered, the more it seemed that the BT issue was also intermittent.

Looking at the service manual, it seemed all the BT functions reside in a module, connected by a cable to the main board. In brief, I replaced first the module (worked for a bit, then back to the way it was before). Yesterday I replaced the main board.

Initially everything seemed to work great. A few hours perhaps. Now, there are intermittent issues again. Th SAME issues.

So my thoughts go to the connecter. It’s the one part of this BT/Wifi circuit I haven’t swopped out. Having said this, I had done a basic continuity test on each of the little cables which seemed fine. I’m totally stumped!

Please please let there be a solution out there that will resolve this. I’d really appreciate your help.

[BrokenYugo]

Maybe power supply related?

[NizNoz]

Would that be possible? My basic understanding makes me think the problems would be more widespread if it was power-related? Also, since changing the main board the issue occurs less frequently..

[TheMG]

It doesn't hurt to check. Check power supply voltages to make sure they are correct, stable, and don't have excessive ripple. In fact, that's the first rule of troubleshooting!

A unstable high ripple power supply output (usually due to bad caps) can cause all sorts of weird, erratic and intermittent behaviour of what it's powering.

It's possible replacing the main board slightly improved things because it has healthier decoupling capacitors, which are helping filter the power supply output just a little bit.

[NizNoz]

Thanks for pointing me in the right direction. I don't understand 50% of what you just mentioned.. but there's google and the forum Sounds like an oscilloscope is going to come in handy. Need one of those...

[NizNoz]

This is getting so frustrating 🙁 I reached out to the vendor who sold me the main board and she’s doubtful such a specific issue could be due to an issue on the power board (I assume that’s where the ‘voltage ripple’ issue might be originating if there is indeed such a thing going on (and considering I replaced the wifi module and main board). She also sells the power boards, so she has no incentive to deter me from buying a new power board.
I’ve added a pic for what’s it’s worth. I don’t see anything obvious on the power board, but since I’m new to this I thought someone here might see something I don’t..

[NizNoz]

In case anyone’s interested, here’s the service manual.

https://www.electronica-pt.com/esquema/func-download/71265/chk,5ae810067408d524b7c76337b9dd3d1b/no_html,1/

[NizNoz]

Now there’s restarts. And IR remote is acting strange. I guess this is probably confirmation that the issue is not localized to the wifi/BT circuits but includes power board components? Could you point me to any resources that could help me in localizing the issue? At this point I’ll be looking for ‘bulging capacitors’. But are there any other ‘quick win’ approaches?

[NizNoz]

I noticed high “SerDes” error counts in error log. Any thoughts about what this might mean?

[BrokenYugo]

Without an oscilloscope to check for excessive high frequency ripple or good ESR meter to check the capacitors about all you can do if power supply is suspected is replace every electrolytic cap on the board aside from the two big skinny ones. Choose low ESR 105*C parts and understand that this is shooting in the dark.

[tszaboo]

I noticed high “SerDes” error counts in error log. Any thoughts about what this might mean?

SERDES is a high speed digital circuit. Most likely the one driving the optical link.
I think you might have a dirty digital supply voltage. 3.3V, 2.5V 1.8V or similar. Lots of noise on it, causing intermittent, seemingly unrelated issues.

[NizNoz]

Thanks for that. I’ve posted this across various sites and not many people seem to know anything about Serdes. Would the issue likely be on the SMPS or the main board? (In this case there’s a separate box, with its own SMPS and separate main board connected to the chassis by optic fibre cable. I’m referring to the SMPS and board in the external box).

[tszaboo]

Thanks for that. I’ve posted this across various sites and not many people seem to know anything about Serdes. Would the issue likely be on the SMPS or the main board? (In this case there’s a separate box, with its own SMPS and separate main board connected to the chassis by optic fibre cable. I’m referring to the SMPS and board in the external box).

It could be on the main board. There seems to be a bunch of inductors there. Probably they get 12-20V and step it down to the digital levels.
SERDES means Serializer-Deserializer BTW.

[andy2000]

It's worth looking over the power supply for bad soldering.  It's also possible that the replacement main board is bad.  Have you checked inside the external box?  Maybe the cable is damaged.

[BrokenYugo]

Speaking of this external box, how is that powered? Have you looked in there?