Intermittent HDMI or Grounding Issue

[beavislong]

I just got a new X1 dvr 1 box

I am having an issue with HDMI connectiviy to my system.  The HDMI signal with come in and out with directly connected to the TV.  I normally have things connected through my Yamaha receiver.  When I connect my comcast box to the receiver It affects all HDMI ports.  For instance if I have my Xbox One turned on and my reciever set to the port for the Xbox  if I plug the HDMI into the Comcast box the display on the goes blank.  If I unplug the Comcast box the Xbox is displayed again.  

I had a tech come out and check out the lines.  Said signal was fine.(my modem has always worked)  The only way we could complete the setup was to connect a coax cable to tv.  No issues with display.  Once we got the box initated we unplugged the coax and went back to the HDMI.  Still experience issues. 

The tech though maybe it was a grounding issue with the TV.  We plugged the TV into another outlet with the same issue.  I have a a passthrough HDMI from my family room into my master bedroom and we connected the comcast box to the TV in the bedroom and had no issues.

Back to the Family room.  The tech had a theory.  He reconnected the coax to the TV and once he did the HDMI issues disappeared.  

Did the coax connect resolve a ground issue?  If so is the ground issue in the TV itself?  In the electrical? (My house is a new construction only a year old so everything is up to code) Could it still be a comcast ground issue?  The tech did check the outside ground and said it was good.

Any help or thoughts would be appreciated.

[CCAndrew]

It sounds like an HDCP issue with your receiver as that’s the only common denominator in your troubleshooting

[beavislong]

not sure it is the reciever.  The reciever worked perfectly until I introduced the Comcast box.  I can connect the HDMI that I have run to bedroom to the receiver's output and that would tell me if is the receiver.  I'll update after I try.

Also,  I'm getting picture just fine with HDMI after connecting the coax from the box to the TV.  how does that play in?

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@CCAndrew wrote:
It sounds like an HDCP issue with your receiver as that’s the only common denominator in your troubleshooting

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[CCAndrew]

HDCP compliance is a necessity for the X1 platform, the cable is “tricking” the system. Have you tried going cable box to tv to receiver instead?

[Rustyben]

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@CCAndrew wrote:
HDCP compliance is a necessity for the X1 platform, the cable is “tricking” the system. Have you tried going cable box to tv to receiver instead?

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if the audio from the x1 set top box is still working then it is HDCP.  note that it is the TV (sink in HDCP technology jargon) that turns off the video until that hdmi feed ends. 

[beavislong]

Ok,  when the picture cuts out so does the sound.

I removed the receiver from the equation and still get the same result.

What leads me to believe it is a ground issue is that when I have the input on the tv connected to the output from the reciever  it will cause the display to go blank on all inputs as soon as the hdmi cable from the  Comast box touches the reciever(before I get it seated in the port)

Thoughts?  

[CCAndrew]

If it was a ground issue, shouldn’t it affect the other tv too that you said worked just fine.

[beavislong]

I guess that depends on if the ground issue is resolved by the tv that worked fine being plugged into a properly grounded outlet.

I did realize last night that my TV will flicker when I turn my ceiling fans on in my great room.  That is concerning.  I have an electrician coming at some point.