Block Diagram of Colour Television
According to Block Diagram of Colour Television Sets In a colour television receiver, additional circuits are provided to deal with the colour.
The only difference between black and White Television set and colour Television set is the IF circuit is the importance of bandwidth for colour receivers. Remember that video frequencies around 3.58 MHz just show details in monochrome, but these frequencies are essential for colour information. Without them, there is no colour. This is why the fine tuning control on colour television sets must be tuned exactly, or else the colour disappears, along with the higher resolution.
The sound is usually taken off before the video detector in colour sets, and a separate converter is used for it, instead of taking it from the video detector. The reason that this is done is to minimize a 920 KHz beat signal that can result between the 3.58 MHz colour subcarrier and the sound carrier signal. This signal would show up as interference in the television picture.