Changhong LS03W, 20LS03W Schematic
LCD COLOUR TV
SERVICE MANUAL
CHASSIS NO.:LS03W
Please read this manual carefully before service.
1
Catalog
Chapter 1: Specifications and Composition......................................3
Chapter 2: Function Introduction of Main ICs...................................5
Chapter 3: Analysis of Signal process flowchart and key point
measure date......................................................................7
Chapter 4: Maintenance Procedure and Examples of Typical
troubleshooting...................................................................9
Chapter 5: Factory Setup...................................................................15
Appendix 1
Circuit Schematic Diagram............................................18
2
Chapter 1: Specification and Composition
1. Main Feature
Region
Color
RF signal
Video or Y/C signal
Program presetting
Audio output（THD≤
Power source
Sound demodulator
VGA input
YPBPR input
HDMI input
OSD language
Auto Off without
Signal Reception
Energy saving system
Plug and Play
system
Sound
system
7%）
CCD
America
NTSC、PAL M、PAL N
M
PAL 、NTSC、SECAM
68 （AIR：2-69）
125 CABLE：1-125）
6W+6W
100V～240V
Yes
BTSC
Yes
Yes
Yes
English, French, etc.
15 minutes
Customer could adjust LCD screen backlight brightness manually to save
energy.
LCD TV could be used as computer screen, no need for the installation of
software, which is Plug and Play in real sense
2. Unit IC Compositions：
The LT32GR01U is made up of switch power, system control circuit, video processing
circuit, audio processing circuit, Power Amplifier circuit, AV input circuit, LCD screen
module. Block circuit diagram is shown as below:
3
TUNER
AV1/AV2 LVDS
S-VIDEO
YPbPr1/YPbPr2
VGA
MST9U19
DECODER/
SC
LAER
PANEL
TV Audio
HDMI
POL4558
Audio switch
Audio1(for AV1/YPbPr1/S-VIDEO)
Audio2(AV2/YPbPr2)
Audio3(VGA)
HCF4052
POL4558
Sound effect
AMP
TPA300BD2
3. Introduction of PCB module
The LT32GR01U is made up of power board, Side TV board, remote control reception
board, key board, and mainboard. The table below is the introduction of the function of all printed
Board modules.
No Parts Description
1
Mainboard
Module
2
Remote reception
module
Mainboard module is the core of LCD TV signal processing. Under the
control of the system control circuit, It undertakes the task of converting the
external input signal into the unified digital signal that the LCD screen could
identify. Mainboard controls the whole machine through IIC bus, decode
VIDEO signal, controls the Video (brightness, contrast, chroma, hue,
definition etc), white balance adjusts, generates OSD, de-interlaces signal,
converts signal frequency, and finishes signal A/D and D/A conversion,
video enhancement, LVDS signal coding and output; it has Scart , S-Video,
AV , YPbPr, HDMI and PC interface, Tuner input, sound demodulation,
sound processing, sound power amplifier, and online update.
The remote reception board module is constituted by an indicator-light and
a remote reception. Customer could manipulate the LCD TV by using
remote controller very conveniently. By the color of the indicator light, the
operation mode of the LCD TV could be judged (red is standby, green is
power on).
Built-in powe
r
3
board module
Convert the 100V～240V （50/60HZ）AC into DC, output have +24v, +12V,
+5V, and the +5V_STB in standby state.
Keyboard
4
module
LCD screen
5
module
6 TV board TV board is used for RF signal.
Keyboard module has 7 function keys (program +/-, volume +/-, AV/TV,
menu ,power), customer could use the key to operate the TV freely.
LCD screen has built-in inverter that convert DC into high voltage AC signal to
turn on the backlight CCFL (Cold Cathode Fluorescent Light); the LCD screen
process the video signal from signal board and reappear.
Chapter 2: Function Introduction of Main ICs
1. Main ICs and functional modules of the LT32GR01U
Mainboard
No. Item no. Model Main function
1 U10
2 U2 EONP40-50GCP Flash, Store the Control program.
3 U1 AT24LC32 EEPROM
4 U3 SI9435 MOS switch
5 U4 TPA3008D2 Audio amplifier
6 U5 CM1117ADJ-3.3 5V to 3.3V DC conversion
7 U6 BM1084ADJ-1.8 3.3V to 1.8V DC conversion
8 U7 BM1084ADJ-3.3 5V to 3.3V DC conversion
9 U11 CD4052B Audio switch
10 U12 PI5V330S Video switch
11 U13 FM24C02 EEPROM
MST9U19
Video decoder, Audio signal processor, image
processor, A/D and D/A conversion
12 U14 FM24C02 EEPROM
TV board
No. Item no. Model Main function
5
1 U1 TSN6312-N Tuner output sound IF and video signal
2 U2.U3 78M05 12V to 5V DC conversion
Function introduction of ICs or functional modules of the LT32GR01U
1.Tuner (JS-6H2/121 or CDT-6GPL22-00)
Pin No. Definition of pin Function description
1 Ground Ground
2 Ground Ground
3 VCC +5V power
4 SCL IIC bus (clock)
5 SDA IIC bus (data)
6 AS Ground
7 NC No connection
8 NC No connection
9 Ground Ground
10 Ground Ground
11 SIF/Out Sound intermediate Frequency output
12 Video/Out CVBS signal output
13
VCC（+5V）
+5V power
14 Audio/Out Audio signal output
2. Image processing IC MST9U19
Main features:
●Integrated 6th Generation Motion and Edge Adaptive De-interlacing
● Integrated ADC
● PC auto tune
●Built-in 8-bit LVDS Transmitter
● 6th generation cubic-4 image scaling engine
● Advanced Chroma Processing and Dynamic Contrast Function
● Green color stretch, blue color stretch, skin color enhancement
●Integrated 6th Generation Motion Adaptive 3D Digital Comb Video Decoder with
Programmable Filter
●60Hz/100Hz interlaced scanning and 50Hz/75Hz progressive scanning
● frame rate conversion
● Advanced Film Mode Recovery-3:2/2:2 pull down
● Build-in A/D conversion function
● Teletext function
● Supports 16/32bits SDRAM memory interface
● Multi-screen display mode
● OSD and VBI/Closed caption and advanced OSD engine
6
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.
1. Video signal flow
RF signal is demodulated by tuner, then the obtained video signal and signals inputted
from COMPONENT terminal, 2-way AV, S-VIDEO, 2-way YPBPR interface, VGA interface
and HDMI interface are all sent into video-processing IC MST9U19 for decoding. The
different format input signals are changed into uniform LVDS signals, and are sent to LCD
screen.
2. Sound process flow
RF signal is demodulated by tuner, and then the obtained SIF signal (SIF-2 signal) is
directly processed by MST9U19. The output audio signal of MST9U19 is sent into power
amplifier TPA3008D2.
Signals from HDTV terminal, AV terminal, YPBPR interface and PC Audio are also
sent into MST9U19 for demodulation and sound process. The output audio signal is sent
into power amplifier TPA3008D2,
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 TPA3008D2. +5V output is changed into 1.8V output and 3.3V output
by DC/DC 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 infrared receiver and EEPROM etc, and
will be cut off when the AC is turn off.
(1) The composition and distribution of the TV power supply
+12V power
supply
J4
Pin 10.11
+5V
power
supply
J4
Pin 3,4
7
12V AUDIO
+5V_LC
V_VIDEO
+5V_4052
U4 power amplifier
TPA3008D2
Pin14.15.22.23.33.38.39.46.47
AUDIO_MUTE circuit
U10 PI5V330
Pin16
U11 CD4502B
Pin16
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