If you have just the basic/expanded package and some channels have these symptoms: no audio, may sound like a radio station or spanish speaking on an engish speaking channel. then your tv is set to SAP (secondary audio program) Check the owners manual to see where in the menu the SAP is located and turn it off. It may even be on the remote control.
If you have just the basic/expanded package and some channels have these symptoms: no audio, may sound like a radio station or spanish speaking on an engish speaking channel. then your tv has SAP (secondary audio program)turned on. If you aren't sure how to find it, check the owners manual to see where in the menu the SAP is located and turn it off. This is the first thing I suggest you try.
I had the same problem on all my digital channels from comcast through the QAM tuner. After a power outage, the TV went through a re-boot and the audio returned. Coincidence ? maybe , but worth a try, check your manual for re-boot instructions.