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HDMI No Signal Issue unless directly to TV (No Receiver, Xbox bridge)

Frequent Visitor

HDMI No Signal Issue unless directly to TV (No Receiver, Xbox bridge)

I am having two issues (possibly related,) which onsite techs have been unable to solve. 

 

First, I am only able to use my Xfinity cable box when the HDMI is plugged directly into my Television HDMI port from the cable box. “No Signal” issue when connecting HDMI Out from the Xfinity box into either my Onkyo receiver or my xBox. The Onkyo would not indicate that an HDMI signal is received. Connecting the Xbox One to the same receiver ports, a signal is received. The tech suggested the issue is with my Television, but the issue is only  encountered with Xfinity.

 

Update: Even when connected directly to my LG TV, the cable signal will flicker off every minute or so.

 

Both the Onkyo Receiver and LG TV are both ~8 years old. LG TV has the ARC HDMI port. 


Troubleshooting Performed:

  • Xfinity Box was replaced Twice.
    Replaced all HDMI Cabled with new  RocketFish cables. Same issue.
  • Xfinity on-site tech replaced all coaxial within and to my home from outside.
  • Tested all the same HDMI In ports using my xBox one and HDMI signal is not an issue 

Test connection and results (using the same ports on devices for consistency.)

  • Xfinity to TV Directly - Signal working, video displayed
    Path: Coax from Wall > Surge Protector (to eliminate buzz) > Xfinity Receiver > Xfinity HDMI OUT > LG TV HDMI IN.
  • Xfinity to Onkyo Receiver to LG TV - No Signal
    Path: Xfinity Box > Onkyo Receiver > LG TV HDMI 1
  •  Xfinity to XBOX ONE to TV - No Signal
    Path: Xfinity Box > xBox One >  LG TV HDMI 1
  •  Xfinity to XBOX ONE to Onkyo Receiver to TV - No Signal
    Path: Xfinity Box > xBox One > Onkyo Receiver > LG TV HDMI 1

I don’t know why the Xfinity signal will ONLY work when directly connected to the TV HDMI 1 port. 

NOTE:  HDMI 1 on the TV is the ONLY port (of three) which will display the signal from the cable box.

Plugging the same HDMI cable into any other port, No Signal, even when directly from the xfinity box.

 

Second Issue:  There is a constant buzzing and electrical sound unless I pass the coaxial IN through a surge protector before connecting to the cable box.  Without the surge protector in place, I will notice a buzzing the moment I touch the HDMI out cable to the  HDMI IN on the Television.  Again, all coax from Xfinity was replaced.

Frequent Visitor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

*Addendum: The Xfiunity Box was replaced twice, neither corrected the issue.

Expert

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV


@Larsogm wrote:

*Addendum: The Xfiunity Box was replaced twice, neither corrected the issue.


it sounds like you have a floating ground (danger including possibility of death caused by shock). an in-house very-trained tech should be able to determine the grounding issue and that may resolve other issues if the equipment is not damaged. the coax enters the home (plant) and is to be connected to a ground block (to earth ground) and a POE filter.  Any impressed voltage arriving on the coax would be shorted to ground by that grounding block. Please be very careful until this is resolved. 



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Frequent Visitor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

Thank you. A floating around would be electrical in my home, not related to Xfinity?

Xfinity has replaced the coax within and everything from 'the box' to my home.
Expert

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV


@Larsogm wrote:
Thank you. A floating around would be electrical in my home, not related to Xfinity?

Xfinity has replaced the coax within and everything from 'the box' to my home.

a hot ground (ungrounded/floating) should be addressed as soon as possible. As a customer we do not know if you are in a home, condo, apartment, etc nor of devices connected, home wiring outlet polarity, and other devices connected to the equipment.



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Frequent Visitor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

Change the setting on the Comcast Box to 1080i and it will work. I had the same issue. The new updated boxes come with 1080p as default and older recievers will not pass through 1080p.

Expert

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV


@attilio209 wrote:

Change the setting on the Comcast Box to 1080i and it will work. I had the same issue. The new updated boxes come with 1080p as default and older recievers will not pass through 1080p.


1080i is for CRT (projector) HD tv's while flat screens use p (progressive). Please do not destroy the digital video stream by forcing the box to convert to interlaced. 720p or 1080p is best for the digital TVs.



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Frequent Visitor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

You will not see the difference from 1080P ro 1080i unless you are watching 4k. Just make the chane to 1080i so your reciever will work. If you dont, you will have to money rig wiring to work. 

Expert

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV


@attilio209 wrote:

You will not see the difference from 1080P ro 1080i unless you are watching 4k. Just make the chane to 1080i so your reciever will work. If you dont, you will have to money rig wiring to work. 


4k is only p (progressive). please do not advise us to change to a deprecated (out of date) format like interlaced. 



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Frequent Visitor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

RustyBen,

 

I have now had Xfinity (twice,) ComEd, and a licensed electrician come to my condo and check everything out.    
There is no floating ground in my home.  (I've now spent nearly $200 ($60 Xfinity visit, $125 Electrician) trying to identify the problem.

 

  • Original HDMI issue persists
  • The cable signal will flicker off and on every few minutes even when connected directly to the TV.
  • Buzzing persists when connecting the Coaxial directly from the wall to the Xfinity box. 

Are there any Xfinity TechSupport folks out there who can assist? 

Cancelling Xfinity TV seems like the way to go if this cannot be resolved. 

Frequent Visitor

Multiple HDMI No Signal Issues

Cross Posting here, as I originally posted in X1 area. I am not an X1 user.

 

First, I am only able to use my Xfinity cable box when the HDMI is plugged directly into my Television HDMI port from the cable box. “No Signal” issue when connecting HDMI Out from the Xfinity box into either my Onkyo receiver or my xBox. The Onkyo would not indicate that an HDMI signal is received. The port does work with an xBox one, so it's not the receiver.  Additionally, even when connected to the HDMI Port on the TV, the video will flicker off then back on every 3-5 minutes.

 

Both the Onkyo Receiver and LG TV are both ~8 years old. LG TV has the ARC HDMI port. 


Troubleshooting Performed:

  • Xfinity Box was replaced Twice.
    Replaced all HDMI Cabled with new  RocketFish cables. Same issue.
  • Xfinity on-site tech replaced all coaxial within and to my home from outside.
  • Tested all the same HDMI In ports using my xBox one and HDMI signal is not an issue 

Test connection and results (using the same ports on devices for consistency.)

  • Xfinity to TV Directly - Signal working, video displayed
    Path: Coax from Wall > Surge Protector (to eliminate buzz) > Xfinity Receiver > Xfinity HDMI OUT > LG TV HDMI IN.
  • Xfinity to Onkyo Receiver to LG TV - No Signal
    Path: Xfinity Box > Onkyo Receiver > LG TV HDMI 1
  •  Xfinity to XBOX ONE to TV - No Signal
    Path: Xfinity Box > xBox One >  LG TV HDMI 1
  •  Xfinity to XBOX ONE to Onkyo Receiver to TV - No Signal
    Path: Xfinity Box > xBox One > Onkyo Receiver > LG TV HDMI 1
  • Xfinity will ONLY work when directly connected to the TV HDMI 1 port

NOTE:  HDMI 1 on the TV is the ONLY port (of three) which will display the signal from the cable box.  Plugging the same HDMI cable into any other port, No Signal, even when directly from the xfinity box.

 

Second Issue:  There is a constant buzzing and electrical sound unless I pass the coaxial IN through a surge protector before connecting to the cable box.  Without the surge protector in place, I will notice a buzzing the moment I touch the HDMI out cable to the  HDMI IN on the Television. 

Troubleshooting: All Xfinity coax/connections within and outside of the home from Xfinity were replaced.  It was suggested that I may have a 'floating ground,' but I did have both ComEd and an electrician come out to inspect my home, no issues were found. 

 

Official Employee

Re: Multiple HDMI No Signal Issues

Hi, Larsogm. Are you using the same HDMI port on your TV when troubleshooting this?


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Frequent Visitor

Re: Multiple HDMI No Signal Issues

Hi there,
Yes. Using the same HDMI port on the TV.
Greg
Frequent Visitor

Re: Multiple HDMI No Signal Issues

Still struggling with this.  Does anyone have any suggestions? 

 

Contributor

Re: Multiple HDMI No Signal Issues

Replace the TV as it appears to have an internal short to ground which is the likely cause of all the current failures.   Verifying no AC power on the incoming cable shield was very good, and if that is ever a factor it can be fixed by regrounding/replacing the demarc and/or re-grounding/verifying the box near the curb or the module in the BIG aggregator-backhaul-thing within a mile or two.

Expert

Re: Multiple HDMI No Signal Issues


@bald271 wrote:

Replace the TV as it appears to have an internal short to ground which is the likely cause of all the current failures.   Verifying no AC power on the incoming cable shield was very good, and if that is ever a factor it can be fixed by regrounding/replacing the demarc and/or re-grounding/verifying the box near the curb or the module in the BIG aggregator-backhaul-thing within a mile or two.


i don't see how you can assume any of that (speaking as a tech). the current failure as you call it is simply a handshake issue where the connection is dropped (part of HDCP). Comcast has stated it is confirmed and some customers have reported an update to firmware will be pushed out (installed) to fix the issue as soon as it is completed and tested.



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New Poster

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

I had the same problem a week ago it’s an LG tv xfinity dvr box and hdmi connection ... the hdmi from the blue ray works fine but the hdmi from the xfinity box does not the tv turns on and off only showing the lg logo

Replaced the cable box and the hdmi cables still the same issue the only solution was to coax from the cable box to the tv

New Poster

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

I have more or less a similar issue. However, if the comacast hdmi is even plugged in to the onkyo receiver it effects the signal to all of the hdmi ins and outs.
Yank the comcast hdmi cable...once unplugged.... everything is fine on ps4, firestick, blue ray, etc.

I replaced a 60 ft cable through wall because i damaged the end from testing and well.... its been fun!

X1 platform non dvr ( sorry dont know box number)
Brand new updated ONKYO tx nr696
Older Mitsubishi projector with 60 ft cable.

Works amazing on all inputs unless comcast hdmi box plugged in.

This is all of a sudden change in last month. Replaced pioneer receiver because of similar issues related to hdmi out....Bang head here->!. Then had to swap out the receiver i bought just before this one under warranty and upgraded because of stock issue. Tech support said to try that first. All because if comcast hdmi is plugged into receiver. Comcast box can even be powered down!!!

Any thoughts or resolution on this matter known about?

Had comcast out today to address/clean up connections, and replace older boxes.

Said everything checks out but it doesnt.

Was thinking about getting a switch or see if the is some filter for this issue but..... not sure what to do.

Thanks for your time.

MJ
Expert

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV


@Fiveliterdriver wrote:
I have more or less a similar issue. However, if the comacast hdmi is even plugged in to the onkyo receiver it effects the signal to all of the hdmi ins and outs.
Yank the comcast hdmi cable...once unplugged.... everything is fine on ps4, firestick, blue ray, etc.

I replaced a 60 ft cable through wall because i damaged the end from testing and well.... its been fun!

X1 platform non dvr ( sorry dont know box number)
Brand new updated ONKYO tx nr696
Older Mitsubishi projector with 60 ft cable.

Works amazing on all inputs unless comcast hdmi box plugged in.

This is all of a sudden change in last month. Replaced pioneer receiver because of similar issues related to hdmi out....Bang head here->!. Then had to swap out the receiver i bought just before this one under warranty and upgraded because of stock issue. Tech support said to try that first. All because if comcast hdmi is plugged into receiver. Comcast box can even be powered down!!!

Any thoughts or resolution on this matter known about?

Had comcast out today to address/clean up connections, and replace older boxes.

Said everything checks out but it doesnt.

Was thinking about getting a switch or see if the is some filter for this issue but..... not sure what to do.

Thanks for your time.

MJ

the reported issues so far have been for only the x1 4k DVR (xg1v4). 



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Contributor

Re: HDMI No Signal Issue unless HDMI is plugged directly into TV

the buzzing sound is probably the crux of the issue.   it is almost certainly a "60 cycle hum" from the AC power but caused by a current-limited short to ground rather than a floating ground.   Root cause is likely one of the pieces of gear or power cords or connectors or HDMI cables.  Suspect them all equally not just the comcast gear.  Check for a hot-case or hot-shield grounds on *every* piece of equipment, the shield/outer-connector of every coax:   Measure the voltage from the case/shield to two different grounds on two different outlets/standpipes while you reproduce the buzzing problem.  The measured voltage should stay at zero in every case.   Any nonzero voltage will indicate the faulty gear/cable/connector that requires swap or proper grounding .   Another possibly costlier approach is to obtain a temporary duplicate gear/kit/cable for everything, like with a duplicate HDMI wire run in parallel down a hallway/stairs just as a test.   Swap one device at a time, one wire at a time, and retest - until buzzing sound is eliminated, and you will have identified the bad kit/cable/connector.