I have always used tuner A. Today, I try to use tuner B, just switch Coaxial cable from A to B. the SNR is the same as A, however, an error says that "cannot find PAT". I tried to manual scan using tuner B, and 0 service searched.
Therefore I switch it back to tuner A, and everything is OK.
Is it another hardware defect or I am not in the right way ?