I have three items using cable, modem, two TV's. But I have four cable lines leaving the outside box. I've traced all the lines through the crawl space and found the fourth at an outlet behind a cabinet. I attached a spare small TV, programmed the TV however I get no channels. The TV has a digital tuner. Shouldn't I get basic cable without a box? How can I as a homeowner check if the line is active. I can't open the outside box because it has a special locking device.