This set stopped detecting channels when I run a scan. I ran the coaxial from the cable direct to the tv instead of the cable box and it read about 16 channels but the channel numbers were odd like 10

go to the Menu and you should find it.

Where is your antenna hooked up? Thru a cable box? Direct to tv? Completely describe setup, maybe post photos

A channel scan is a vital part of utilizing your cable TV service. When a coaxial cable is connected to a TV, sometimes it will not display any channels until you configure the TV for your specific cable connection and scan for available channels. A channel scan can be applied to basically any type of TV or TV/VCR combo, even if you are missing its remote control.

Read more : http://www.ehow.com/how_6875646_do-old-tv_vcr-tv-remote_.html
Instructions

1. • 1 Bring up the TV's menu. Look for a button on the front panel of your TV/VCR labeled "menu" or "setup." Press it and you should see a menu appear on the screen. Part of the menu should inform you what buttons you can use to navigate through the menu. If not, try using the volume buttons or channel buttons on the front of the TV and see if pressing those allows you to navigate through the menu.
     
   • 2 Specify channel scan settings. Once you are able to navigate through the TV's menu, look for the "channel scan" "auto-program," or "auto-tune" option. This may be inside one of the TV's sub-menus such as "setup," "channel setup," or the like. The key of this step is to specify your cable settings before running your channel scan. The "tuner mode" option needs to be set to "cable" rather than "air" or "antenna." You may have to specify what cable type to use, this will be set to "std" or "standard" for the vast majority of cable providers. If you are not certain what cable type you use at home, contact the technical support department of your cable provider.
     
   • 3 Run a channel scan. Once the scan settings have been set properly, run the scan (usually done by pressing a "start," "scan" or "begin" button.) When the scan is complete, check to see if you are getting all of your channels. Contact your cable provider if you are not sure how many channels you are supposed to be getting.
     

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good luck

If you hookup your TV directly to the coaxial cable, bypassing the cable-box, do you get a few channels? If so, then the coaxial cable is carrying a signal, which is good.

How are you hooking the output from the cable-box to the input(s) on the TV? Coaxial output port on box to coaxial input port on TV?
Red/blue/green "component" outputs on box to matching inputs on TV? Red/White audio outputs on box to red/white inputs on TV? HMDI output from box to HDMI input on TV?

You have to "tell" the TV which of the inputs:
* coaxial (with TV set to Channel 3 or 4)
* component
* HDMI
to "listen" to.

If you are receiving a "No Signal" error message, verify that:

1. All of the cables physically connected to the TV and the input device are secure.
2. The input device is turned on.

Your TV needs to scan for channels before it can show programming from an antenna, from cable TV when the cable comes directly from the wall (no cable box), or from a cable or satellite box connected to the TV with a coaxial (RF) cable. Do not scan for channels if you have a cable or satellite box connected using AV (Composite), Component, or HDMI cables. The box selects the channel, not the tuner inside your television. If you are not using the "TV" input, press the INPUT button on your remote until the correct input mode is selected.
To perform a channel scan using the coaxial input:

1. Press the INPUT button on your remote to view your current input source. The TV (coaxial cable) input must be selected. This may appear as "TV," "ANT," or the channel and call letters of a station.
2. If the TV input is not selected, press INPUT until the TV input mode is selected.
3. Open the on-screen menu and select TV or Tuner option. (This varies by model.)
4. Highlight Tuner Mode and select the correct option:
   • Antenna-over-the air signals from an antenna
   • Cable-direct from the wall cable TV, or a cable or satellite box connected to the TV with coaxial cable
5. Select Auto Search or Auto Channel Scan. (This varies by model.)
6. When the search reaches 100% complete, exit to the menu.
7. Check the available channels:
   • Antenna or direct-from-wall cable-Press the Channel Up and Channel Down buttons on your VIZIO TV remote to view the available channels.
   • Cable or satellite box- Will return only one channel. Use the cable or satellite remote's Channel Up and Channel Down buttons.

If this does not resolve the issue, power cycle the TV and then re-run the channel scan:

1. Turn off the TV.
2. Unplug the TV from the electrical outlet.
3. While the TV is unplugged from the wall, press and hold the Power button on the TV for 30 seconds.
4. Release the power button.
5. Plug the TV back into the electrical outlet.
6. Turn on the TV.

Note: There is also an option to reset the TV to the factory default settings. This option is in either the SETUP or SYSTEM section of the on-screen menu. The option may be "Reset all settings", "System Reset," or "Reset & Admin." Consult your TV's user manual for the location and steps for resetting your model.

1. Remove the coaxial cable from the DTV/TV connector on the back of your television and perform a channel scan to clear the existing channels. See the procedure above. This should not find any channels.
2. Re-attach the coaxial cable to the DTV/TV connector and perform a new channel scan.

This video shows troubleshooting steps to use when a "No signal" message appears.

Hi -

If you have a cable TV line connected directly to the TV, an antenna or a cable box connected by coaxial cable, I would suggest running the automatic channel scan (AUTO-PROGRAM) again:

1. Press the AV key on the Advent remote control repeatedly until TV is displayed in one corner of the TV screen. If you don't have the Advent remote, use the TV/AV button on the front of the TV.
2. Press the MENU key on the advent remote or the front of the TV to open the on-screen menus.
3. Use the CH+/- keys on the remote or on the front of the TV to highlight PRESET then press VOL+ to select.
4. Use the CH+/- keys on the remote or on the front of the TV to highlight ANTENNA then use the VOL+ key to select either AIR (for antenna) or CABLE.
5. Use the CH+/- keys on the remote or on the front of the TV to highlight AUTO-PROGRAM then press the VOL+ key to start the automatic channel scan.

Once the channel scan is complete, the TV should automatically return to viewing the first channel found during the scan. Do not press the MENU key during the scan or the scan will not complete.

If you are using a cable/satellite receiver and it is connected to the TV by any means other than a coaxial cable, you do not need to run the channel scan. You should simply select the correct AV input using the AV key on the remote or the TV/AV key on the front of the TV (see step 1 above).

If you have done all of the above and you are still unable to get the channels on your TV, please post back for further assistance. You can reply to me by clicking on "Add a Comment" below your question. Please let me know whether you are using a direct cable line, antenna or cable box, etc.

Regards,
BElectric

I'm thinking there might be a setting in the cable box that may be sending the wrong bit rate for PCM 2-channel audio but usually the receiver decodes that stuff fine. Just the same, I'd give Comcast a call.

I run the video from my cable box directly to the TV (HDMI) and the coaxial digital audio to my receiver so each one can do what it does best with the best possible un-modified source data.

okay lets do a cable check... cable from wall /outside connected to cable box in, from the cable box out to (please note any DVD recorder or VCR should be connected here if you have and then on to TV) TV in ..... TV on , turn to channel 3 (this should be the only ch locked on the TV no scan is needed) you are using coaxial cables... if this was/is a hi def connection (your set should be on component)

Reboot ur DirectTv box.By unplug,replug it and hour later to let the box upgrade it solfware.Go to ur tv menu setup rescan it again for all the channels.It should work now.

i know this problem, happened to me with the comcast Motorola HD receiver box. The key is with the setting in the cable box. Switch on the TV. Set the channel to normal tuner channel 3 or HD input. Turn off the cable HD box. Press the Menu Button on the Cable box or the remote. You should see a Menu. Use the cursor keys to navigate The default setup is also one of the option, Right click on your cursor keys acts like the computer keyboard enter key and applies the change. The default setup is 16:9, the shacking would happen if you have set the picture type to "PAN SCAN". change it to either 16:9 or 4:3 Letter Box. The shacking should stop. Hope it helps.