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Computers and Electronics
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Cabling and Wiring Connection
How to Hook Up a Comcast Cable Box Download Article Written by Jack Lloyd
Last Updated: December 10, 2025 Tested
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Preparing Your TV
|
Connecting the Box
|
FAQ
|
Video
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Tips
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Warnings
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This article was co-authored by wikiHow staff writer, Jack Lloyd. Jack Lloyd is a Technology Writer and Editor for wikiHow. He has over two years of experience writing and editing technology-related articles. He is technology enthusiast and an English teacher. The wikiHow Tech Team also followed the article's instructions and verified that they work. This article has been viewed 597,981 times. Learn more...
Do you need to set up a brand new Xfinity cable box? Prepare your TV by putting the box nearby. Connect the HDMI cable to the TV and cable box, and attach the coaxial cable to the box. Once turned on, call Comcast to activate it. This wikiHow teaches you how to connect a Comcast cable box to your TV.
Setting Up an Xfinity Cable Box
To hook up a new Comcast cable box, make sure the box is in a good position near the TV. Connect the coaxial cable to the box, and then connect an HDMI cable to the box and TV. Once connected and on, call Xfinity to activate it officially.
For popular FAQs on hooking up a Comcast cable box, jump to more common questions.
Steps
Part 1 Part 1 of 2:
Preparing Your TV
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1 Make sure that you have cable installed. If a Comcast representative didn't come to your house to install cable, you'll need to call Comcast and request the installation.
If you call Comcast, be sure to have your account information and ID on-hand.
2 Confirm that you have the correct cables. If your TV is an HDTV, you can use an HDMI cable to connect your Comcast box to your TV; if not, you'll need standard A/V cables (the red, yellow, and white cables) to connect the box to your TV.[1]XResearch source
The cable box should come with A/V cables.
You can usually buy HDMI cables for under $15 online or in a tech store.
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3 Turn off and unplug your TV. Press your TV's "Power" button (or the "Power" button on the TV's remote), then remove the plug from the back of the TV.
Leave the TV's power cable plugged into the wall during the setup process.
4 Move your TV away from the wall if possible. You'll need plenty of space to hook up the cable box, so move your TV and/or entertainment center a foot or two away from the wall. This should give you enough room to attach the cable box without bending any wires.
5 Place the cable box near the back of the TV. It's good to have a general idea of where the cable box will go before you start plugging in wires, so make sure the box is roughly where you want it before continuing.
6 Face the back of the box. You should see several slots and connectors in the back; this is where you'll plug in all of the necessary cables. You can now proceed to connecting the cable box to your cable service and TV.
Advertisement Part 2 Part 2 of 2:
Connecting the Box
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1 Attach the Comcast coaxial cable to the box. Find the cable that Comcast installed—it will usually be sticking out of the floor or the wall behind your TV—and plug it into the metal coaxial input in the back of the cable box, then screw the connector clockwise to tighten it.[2]XResearch source
The cable's end has an attachment resembling a needle in the middle of it.
Your cable box should have a coaxial cable included. If Comcast didn't install a cable for you, you can attach the other end of this cable to the coaxial input in the wall.
2 Plug in one end of the HDMI cable. It goes in the wide, narrow port in the back of the cable box. On most Comcast cable boxes, the HDMI port is either in the bottom-right corner of the box or at the bottom of the box's back.[3]XResearch source
If you're using A/V cables instead, plug each cable into the same-colored port on the back of the box (e.g., plug the yellow cable into the yellow input).
3 Plug the other end of the HDMI cable into the TV. Find your preferred HDMI port on your TV, then attach the cable box to the port in question.[4]XResearch source
If you have a receiver with multiple HDMI ports plugged into your TV, you can plug your cable box's HDMI cable into the receiver instead.
If you're using A/V cables instead, plug the cables into the same-colored ports on the back of your TV.
4 Attach the power cable to a power source. Plug the power cable into a wall outlet or power strip. You should choose a power outlet close enough to the TV that you'll be able to place the box near the TV without stretching or bending any wires.[5]XResearch source
5 Plug the other end of the power cable into the cable box. You should see a circular power input on the back of the cable box; fit the end of the power cable into this input.[6]XResearch source
This input is normally on the right-hand side of the box.
6 Plug back in your TV and turn it on. Doing so will also turn on your Comcast cable box, though you may have to wait several minutes before the box is fully on.[7]XResearch source
7 Change your TV's input if necessary. Press the "Input" or "Source" button on your TV or remote to switch to the input (e.g., HDMI 1) into which you plugged your Comcast box.[8]XResearch source
8 Set up your Comcast remote. Insert the batteries into your remote, then proceed with connecting it to your TV and cable box.[9]XResearch source
Cable box and remote instructions vary from model to model, so consult your remote's manual for instructions on synchronizing the remote with your TV and cable box.
9 Activate your cable box. Once your cable box has been connected, all that's left to do is activate the service. To start this process, you can call Comcast at 1-855-652-3446, or you can go to the activation website at https://www.xfinity.com/activate and sign in.
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Common Questions: Troubleshooting Your Cable Box
Why isn't my cable box connecting to my TV?
If your cable box isn't connecting to your TV, make sure the coaxial cable is properly wired through your house. Additionally, make sure the HDMI cable is in the correct port on both the TV and box. If needed, try a newer HDMI cable.
Do I need Wi-Fi to set up my Xfinity cable box?
You will need to connect your cable box to Wi-Fi to finish the set up process. This is how you'll get the newest updates on your device.
Why does my TV have no sound?
Make sure your TV is set to the correct audio output. If you have external speakers connected, check that they're plugged into the TV correctly.
Video
Tips
Using a power strip (also known as a "surge protector") behind your TV will allow you to organize your power sources without straining any wires. Thanks Helpful 4 Not Helpful 1
Submit a Tip All tip submissions are carefully reviewed before being published Name Please provide your name and last initial Submit Thanks for submitting a tip for review! Advertisement
Warnings
Always unplug your TV before attaching cable boxes, consoles, receivers, or any other equipment to it. Thanks Helpful 4 Not Helpful 3
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Written by: Jack Lloyd wikiHow Technology Writer This article was co-authored by wikiHow staff writer, Jack Lloyd. Jack Lloyd is a Technology Writer and Editor for wikiHow. He has over two years of experience writing and editing technology-related articles. He is technology enthusiast and an English teacher. This article has been viewed 597,981 times. How helpful is this? Co-authors: 5Updated: December 10, 2025 Views: 597,981 Categories: Cabling and Wiring Connection In other languages Spanish Vietnamese Chinese Turkish Japanese
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Yes No Advertisement Cookies make wikiHow better. By continuing to use our site, you agree to our cookie policy. Written by: Jack Lloyd wikiHow Technology Writer Click a star to vote Co-authors: 5Updated: December 10, 2025 Views: 597,981
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Written by: Jack Lloyd wikiHow Technology Writer This article was co-authored by wikiHow staff writer, Jack Lloyd. Jack Lloyd is a Technology Writer and Editor for wikiHow. He has over two years of experience writing and editing technology-related articles. He is technology enthusiast and an English teacher. This article has been viewed 597,981 times. How helpful is this? Co-authors: 5 Updated: December 10, 2025 Views: 597,981 Categories: Cabling and Wiring Connection In other languages Spanish Vietnamese Chinese Turkish Japanese 
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1 Make sure that you have cable installed. If a Comcast representative didn't come to your house to install cable, you'll need to call Comcast and request the installation. 
2 Confirm that you have the correct cables. If your TV is an HDTV, you can use an HDMI cable to connect your Comcast box to your TV; if not, you'll need standard A/V cables (the red, yellow, and white cables) to connect the box to your TV.[1] 
3 Turn off and unplug your TV. Press your TV's "Power" button (or the "Power" button on the TV's remote), then remove the plug from the back of the TV. 
4 Move your TV away from the wall if possible. You'll need plenty of space to hook up the cable box, so move your TV and/or entertainment center a foot or two away from the wall. This should give you enough room to attach the cable box without bending any wires. 
5 Place the cable box near the back of the TV. It's good to have a general idea of where the cable box will go before you start plugging in wires, so make sure the box is roughly where you want it before continuing. 
6 Face the back of the box. You should see several slots and connectors in the back; this is where you'll plug in all of the necessary cables. You can now proceed to connecting the cable box to your cable service and TV. Advertisement 
1 Attach the Comcast coaxial cable to the box. Find the cable that Comcast installed—it will usually be sticking out of the floor or the wall behind your TV—and plug it into the metal coaxial input in the back of the cable box, then screw the connector clockwise to tighten it.[2] 
2 Plug in one end of the HDMI cable. It goes in the wide, narrow port in the back of the cable box. On most Comcast cable boxes, the HDMI port is either in the bottom-right corner of the box or at the bottom of the box's back.[3] 
3 Plug the other end of the HDMI cable into the TV. Find your preferred HDMI port on your TV, then attach the cable box to the port in question.[4] 
4 Attach the power cable to a power source. Plug the power cable into a wall outlet or power strip. You should choose a power outlet close enough to the TV that you'll be able to place the box near the TV without stretching or bending any wires.[5] 
5 Plug the other end of the power cable into the cable box. You should see a circular power input on the back of the cable box; fit the end of the power cable into this input.[6] 
6 Plug back in your TV and turn it on. Doing so will also turn on your Comcast cable box, though you may have to wait several minutes before the box is fully on.[7] 
7 Change your TV's input if necessary. Press the "Input" or "Source" button on your TV or remote to switch to the input (e.g., HDMI 1) into which you plugged your Comcast box.[8] 
8 Set up your Comcast remote. Insert the batteries into your remote, then proceed with connecting it to your TV and cable box.[9] 
9 Activate your cable box. Once your cable box has been connected, all that's left to do is activate the service. To start this process, you can call Comcast at 1-855-652-3446, or you can go to the activation website at https://www.xfinity.com/activate and sign in. Advertisement 
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