no signal when placing comcast box into Yamaha 7.1 system

I am not sure who to contact within your technician department. The tech with whom I spoke at Comcast was singularly uninformed. I spoke with Yamaha and they confirmed that the HDMI capabilities on the 2005 receiver are indeed HDMI 1.0. They suggested that I connect the cable box via HDMI cable directly to the TV and run an optic cable for sound. I did that, but I cannot get any sound out of the box. I did set the receiver to look for that optic input, but again no sound. Is there some setting within the box itself that I need to access so that it puts out audio to the receiver?

@user_lxss6b These are great questions. I would like to start with your Tivo box, it's possible the card is expired. Tivo boxes are becoming what we call end of life cycle as they will not support the newer technology we have. We can troubleshoot but not replace or add new cards. I had a Tivo also, and I use both the Xfinity stream app and boxes in certain rooms.

You can rent one of our cable boxes or use a different compatible device to stream your Xfinity your cable TV service through. I have a link to share with those devices which of many of us any ready have in our home such as the Firestick. You would use our Xfinity stream App https://www.xfinity.com/support/articles/xfinity-stream-app-faqs

Thanks for sharing the type of sound receiver you're using. I have a Bose sound bar setup myself. I have some more questions to ask, so we can get to the bottom of your sound and picture issues. 

Have you reprogrammed your Xfinity remote to control your TV and soundbar since switching out those cables?

I have a link to share with those steps.

First unpair your current remote.

I have some steps here depending on the remote you have. https://www.xfinity.com/support/articles/x1-remote-unpair

Which remote do you have? 

Here are the steps to repair that remote. 

https://www.xfinity.com/support/remotes. First you would select the type of remote you have and from there you would select the option to pair your remote to your TV and then your Yamaha receiver. 

Do you have sound if you bypass your sound bar altogether?

Have your checked all connections to ensure everything is finger tight and secure on your TV, cable box and receiver?

Is the TV and/or receiver plugged into a switched outlet or surge protector? If so, please reset that power strip for us.