Under extended warranty regulation is will only covered all " repair cost " but not for money back / ex-change to other unit. unless the TV " beyond repair ".
there in no problems to repair if the reception is bad . ^ could be the tuner pack / RF module problems . keep in mind > " could be ". . and " MAY BE " because of you Antenna or even is because antenna cable / connection / antenna plug / socket / since you " THINK " look like very sure is because of the Sony Bravia model KDL-46S4100 given trouble , the only way is MADE USE of you extended warranty RIGHT, get it don for FREE , but never hope for refund or exchange.
however . better make sure is because of the Sony Bravia model KDL-46S4100 !
simple way to get answer > just " carry " you Vizio TV from the kids room to " replace " the Sony, plug in the antenna use for Sony.... you get real answer !
Sorry , to me " is not the Sony ". is because of antenna cable / connection / antenna plug / socket .
but you much " carry ' the Vizio TV to the " Sony room " than you get answer !
do it . PLEASE.
BTW .IS YOU SONY BUILT IN ACST DIGITAL TUNER OR USE DIGITAL ACST CONVERTER ?
is could be you digital ACST converter is out too ! 2 year old TV may not built in digital tuner. , make sure about this issue too. you Vizio should be less than 22 months and built in ACST tuner .