Why can a one-piece TV be called a "TV set" if a TV is a single item?
A TV is actually composed of many components with specific functions: a radio receiver, a tuning control, a pre-amplifier, an amplifier, a video processing unit, a display screen. In the early days of TV, before the advent of semiconductors(transistors) and integrated circuits, these components were built with tubes, and each component was large enough to actually be worked on or replaced. Also, for 50 years or more, TV displays were cathode ray tubes (CRTs) called the picture tube; these could also be replaced separately. So the term "TV set" refers to all those components, housed in a single cabinet. Modern TVs have all these components, but in miniaturized digital electronics. The term "TV set" is becoming less common, and will probably become even less so over time.
If you go far enough back in time, you might find instances of a radio being called a radio set.
Set refers to:
- A group of things of the same kind that belong together and are so used: a chess set.
so by TV set you mean all the main parts of it that make it a single product.
TV Set :
- an electronic device that receives television signals and displays them on a screen; "the British call a tv set a telly"
Televisions were generally single-piece units right from the start (except for some fancy console models and the short-lived two-piece Philco setup). But "TV set" was probably the norm until maybe 1960 or 1965, when "set" was dropped.
The reason for this is probably that I lied above -- it wasn't called a "TV set" but rather a "television set" -- the word "television", by itself, referred to the medium, not the box, so "television set" was used to refer to the box. And, obviously, "television set" was then shortened to "TV set".
"TV" and "TV set" share the same meaning. They both refer to a television.