UA65MU6880 HDMI ARC connection issues

[zxiemofo]

I have a Samsung 65inch 4k TV, model UA65MU6880.  It has 3 HDMI input, and HDMI 3 is HDMI ARC.

I have been using all 3 HDMI input at the same time.  HDMI 1 and 2 connected to a TV box and a laptop, and HDMI 3 (ARC) connected to a soundbar.  

But recently when I tried new cable with HDMI 1 and 2 (did not touch the HDMI 3 at all), something weird happened.  Now the HDMI 3 (ARC) can only recognize the soundbar if no other device is connected to HDMI 1 or 2.  Otherwise, the HDMI 3 (ARC) cannot recognize the soundbar and sound can only come out of the built-in speaker.   Which effectively mean, I cannot use the soundbar when using the tv box or the laptop, but can only use the soundbar if I use the TV built-in apps like Netflix/apple TV.  

I tried resetting the TV - did not work.  Tried calling the customer service - asked me to unplug the TV for 15 minutes (says the circuit board will reboot/reset or something) - did not work either.

Anyone has encountered this similar situation, or have some ideas as to what might help? thanks.

[meself]

Enable HDMI-CEC (Anynet+):

Samsung TVs: Navigate to Settings > All Settings > Connection > External Device Manager > Anynet+ (HDMI-CEC) and make sure it's turned on. 

Other TVs: Consult your TV's manual for instructions on enabling HDMI-CEC/ARC. 

3. Configure TV Sound Output:

Samsung TVs:

Go to Settings > All Settings > Sound > Sound Output and select your soundbar.

Other TVs:

Consult your TV's manual for instructions on setting the sound output to the connected soundbar. 

4. Reset the Soundbar:

Power Cycle:

Unplug the soundbar and TV from the power outlet for a few minutes, then plug them back in. 

Soundbar Reset (if applicable):

Some soundbars have a reset button or procedure. Consult your soundbar's manual. 

5. Other Potential Issues:

External Devices: If you have other devices connected to the TV via HDMI, try disconnecting them to see if they are causing interference. 

Firmware Updates: Make sure your TV and soundbar have the latest firmware updates. 

HDMI Lockup: In some cases, an HDMI lockup can occur. Try turning off and on Anynet+ (HDMI-CEC) or resetting the sound settings to factory defaults. 

6. Power Off Sequence:

When using ARC, always power off the TV first, and then the soundbar will power off automatically. If you power off the soundbar first, the TV will stay on and the audio will be output through the TV speakers. 

[zxiemofo]

Thanks! that does not help the issue.  

But I somehow manage to isolate the issue - I have an old macbook air - if I I connect it to the Samsung TV using a mdp-HDMI cable directly, it caused the issue above.  But if I connect the macbook first to a mdp-HDMI adapter first, then connect the adapter to the TV using HDMI-HDMI cable, then no such issue.   So the macbook / cable caused the issue.  Guess I have to work on that instead.