Read some interesting tv stuff here , i started serving my time in the tv trade in 1969 back then tv was mostly valve (tubes us ) in the workshop was still to be found a lot of vintage sets these where mono 405 line with fm video and am audio now it wasnt just as simple as switching on the set some of these monsters had as many as 15 user controls , now most of these early sets where synced of the mains power so when a set was switched on the brightness was turned fully low and the audio volume to mid , as the set heated up and audio was heard you would advance brightness to see a picture , now if your home was powered on a differant power station or phase then the picture would be out of sync vertically and horizontily so you would then adjust hor and ver controls to match the sync of the transmitter studio . Now sometimes at night owing to demand power stations would change taps in there substations or connect to another phase this would mean that your tv would go out of sync and need readjusted this is where the term " the sets on the blink come from "!