by composite i'm assuming you mean Yellow/Red/White cables. This comes up alot. all the outputs are working all the time, heres were things get tricky tho; If you have the box outputting in HD through component or HDMI the STB is goign to be outputting in a 720 format and if you use coax or composite or svideo its not goign to fit on the screen. some stuff will get cut off. if you are using HDMI you can try and have the TV at the other end of the HDMI shut off and see if the STB switches to 480 on its own.