DTV channels are not really "locked." If, after connecting a DTV box to an analogue TV set or setting up a digital TV, you find that you are not receiving all or some DTV channels, it could be because you haven't yet programmed the DTV box or digital TV to pick up the local TV channels. If this is the case, all you have to do to "unlock" the DTV channels is execute a channel scan. Executing a channel scan is a simple procedure.
Connect the coaxial cable wire attached to the TV antenna to the DTV box's RF In nodule (usually labelled "Ant. In").
Screw one end of the independent coaxial cable wire into the DTV box's RF Out nodule. Connect the other end of the cable wire to the RF In nodule on the back of the TV.
Insert the DTV box's power cord into the DC power jack located on the back of the DTV box. Plug the other end of the cord into a wall outlet.
Turn the TV on. Switch on the DTV box. Set the TV to channel 3.
Aim the DTV remote control at the DTV box and press "Menu."
Use the arrow buttons on the DTV remote to browse the menu options. Browse to find the "Channel Scan" menu option. When you find it, highlight and select it to initiate a channel scan. (If the DTV remote control has a "Channel Scan" button, you can simply press this button instead of going through the DTV menu to select the "Channel Scan" option.)
Wait for the channel scan operation to be complete. Do not disrupt the process. While the channel scan is going on, you should see a meter bar on the TV monitor which tells what percentage of the channel scan operation is currently complete. When the percentage bar reaches 100 per cent, the channel scan is finished.
Press the Channel Up or Channel Down button on the remote control continuously to flip through the channels detected by the DTV tuner. If you discover any of your local TV stations are missing, reposition the TV antenna and try performing the channel scan again (steps 2 and 3).
Turn on the TV.
Aim the TV remote control at the TV and press "Menu."
Use the arrow buttons on the TV remote to browse the menu options. Browse to find the "Channel Scan" menu option. When you find it, highlight and select it to initiate a channel scan.
Perform steps 3 and 4 from the previous section.
If any of the local TV channels are still missing even after you reposition the TV antenna and perform another channel scan, you may need to invest in a higher quality indoor TV antenna; or possibly even an outdoor TV antenna. If you're not able to pick up a local TV channel that you used to receive with analogue TV, the problem is likely the result of poor reception rather than a locked channel. With analogue TV, poor reception usually only resulted in a static-filled picture. But with digital TV, poor reception often translates to no picture at all. Once you resolve the reception issue you should be able to use channel scan to pick up the missing channel(s).