Chapter 3: Analysis of Signal process Flowchart and key point
measure date
This chapter mainly introduces the receipt and dispose of AV signal the power supply
system and system control process of this TV. (Model of LT32GJ01E is taken as an example,
other models is similar and will not be explained here for each. There are minor differences in
power supply among different models of LCD screen; the details are shown in Specifications).
1. Video signal flow
RF signal is demodulated by tuner, then the obtained video signal and signals inputted from
COMPONENT terminal, AV, S-VIDEO, 2-way SCART interface and VGA interface are all sent
into video-processing IC SVP-CX32LF for decoding. The different format input signals are
changed into uniform LVDS signals, and are sent to LCD screen. In addition, TV video signal is
processed by SVP-CX32LF to generate 2 CVBS signal, which are used in SCART video
output.
Signal inputted from HDMI interface is decoded into digital video signal BY ANX9011L,
which is sent into video decoding IC SVP-CX32LF for decoding. After procession, the obtained
uniform LVDS differential signal is sent into LCD Screen.
2.Sound process flow
RF signal is demodulated by tuner, and then the obtained SIF signal (SIF-2 signal) and
audio signal inputted from Scart1 interface are directly processed by STV-8217. The output
audio signal of STV-8217 is sent into power amplifier TDA8944J, and the amplified signal is
finally sent into speaker or earphone.
Signals from HDTV terminal, AV terminal, Scart2 interface and PC Audio are first sent into
74HCT4052D for choosing passages, and then sent into STV-8217 for demodulation and
sound process. The output audio signal of STV-8217 is sent into power amplifier TDA8944J,
and finally the amplified signals are sent into speaker or earphone.
After the demodulation and sound effect processing of STV-8217, there is an audio output
which is used for sound output of Scart1 terminal.
3. Power supply system
There are 4 ways of voltage output in the power panel: +24V(6A
) 、
+12V(2A
) 、
+5V(2A)and +5VS(1A). +24V output is provided for LCD screen; +12V output is provided
for power amplifier TDA8944J, and is also changed into +8V output by AZ78L08ZTR-E1 to
supply STV-8217 IC; +5V output is changed into 1.8V output and 3.3V output by DC/DC (such
as AZ1117H-1.8TRE1 and AZ1117H-3.3TRE1) to satisfy the needs ICs. +24V, +12V and +5V
outputs will be cut off in standby state. While +5VS output is the power supply of MCU, infrared
receiver and EEPROM etc, and will be cut off when the AC is turn off.
5V output will be divided into two ways: one way is changed into +3.3V and +1.8V
analogue power supplies through DC/DC converter for STV-8217 IC, ANX9011LF IC etc and
peripheral circuits; other way is changed into +3.3V and +1.8V digital power supplies through
DC/DC converter for SVP-CX32 IC etc and peripheral circuits, and this way of 5V voltage will
be cut off in standby state, while the other way of 5V voltage supply power especially for MCU,
infrared receiver and EEPROM etc, and will still operating in standby state.