State the purpose of the following section in a T. V. set. – NABTEB QUESTION

i. High voltage power supply: It provides enough high voltage to operate the beam of the cathode ray tube. E. g. black and the white needs 12kv while coloured TV require 25kv.

ii. Low voltage power supply: It provides the initial voltage and currents needed for T.V. operation.

iii. Vertical deflection: It deflects the focusing of cathode-ray beam from the top of the screen to its bottom.

iv. Horizontal deflection: This section scans the cathode ray beam from the left of the screen to the right end.

v. Video chain: This section consists of video detectors & video amplifier. They detect video signals and amplified it to a certain strength that can drive the CRT. The contrast control is also associated with this stage. It controls the strength of the video signals.

vi. Sound chain: Sound (audio) chain consist of sound if amplifier, limiter FM, detector, audio amplifier and loudspeaker. They also provide sound at 10.7MHz FM for TV.

vii. Synchronizing: Is to keep in step the transmitter and receiver signal so that there will be an agreement between the baseboard channel selection at the two ends.

viii. Colour: It’s responsible for the chrominance (live) of the colour TV.

ix. Cathode ray tube (CRT): It is a vacuum tube whose function is that of a visual displaying device i. e. it is a transducer which converts the received electrical signal back into picture (light) signal on the T. V. screen.

x. Mixer: The local oscillator (Fo) and RF (Fr) signal combined or heterodyned at the mixer to produce a different frequency called I. F.