LG TH-20LA60PS Service Manual page 18

1. Video Controller Unit & Display Data Conversion Unit
The video controller unit receives the video signals inputted through the tuner, AV and S-Video terminal. It converts them into
an ITU656 signal through the microcomputer (VCTI) combined with the video decoder that integrates various functions in
one chip. The signal is inputted to a scaler (GM2221) and then sent to the 20°± LCD module as a TTL output.
VCTi is the main microprocessor that handles video signal processing and sound signal processing. It also manages the RF
signals received from the tuner.
The scaler can control timing to fit into the LCD panel, and can also control the size and position of the input signal.
2. Power Supply Unit
The power supply unit provides 15V and 5V DC power to the main board.
The PWM Step- Up DC/ DC Converter circuit is used to generate the 33V used for the tuner.
15V is directly used by the sound amplifier IC. 15V is used to generate 12V for Panel and is also used to generate 5V and
3.3V power through the Step-Down DC / DC Converter. 5V power is converted to 3.3V and 1.8V power through the
regulator, which in turn supplies electrical power for ICs such as VCTI and scaler.
BLOCK DIAGRAM DESCRIPTION
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