Have you tried a Channel Scan? If the Scan works you may not need a Set Top Box.
Note: All TV manufacturers differ, so menu options, wording and other items may vary. The best way to complete the channel scan is to refer to the TV owner's manual. If that is unavailable, the following general steps should guide you through the process.
1. Press the Menu or Settings option on your television's remote control.
Note: a "Smart TV" may have a smart button that must be used to access the settings menu. It will generally have the manufacturer's logo on it.
2. Locate Channels or Tuner Set Up option.
3. Check the menu for an option of Antenna Type or Connection Type followed by either Antenna or Cable. Make sure that the designated setting is Cable.
4. From the menu, choose Digital Channel Search.
Allow the TV to complete the search. You will see a bar listing how many channels have been found. The process may take up to an hour.
5.Once complete, confirm the menu prompt, then press an exit or quit option.