Changhong LS07 Schematic
LCD TELEVISION
SERVICE MANUAL
CHASSIS LS07
Please read this manual carefully before service.
CONTENTS
PartⅠ: Specification , feature and Composition ………..3
PartⅡ: Function introduction about the main integrated
circuit ……………………………………………………. 7
PartⅢ: Signal Processing Flow chart ….……………………..16
PartⅣ: Typical troubleshooting processing flowchart and
example……………………………………………………….21
PartⅤ: Spare part lists………………………………..………..26
Annex: 1、Circuit schematic diagram of LS07 chassis.……………27
2、Mainboard PCB diagram of LS07 chassis……………..40
3、Final Assembly diagram of LS07 ch assis….…….............44
4、Final Wire Connection diagram of L S07 chassis……….45
PartⅠ: Specification , feature and Composition
1.1、 The Technical Specification：
20 inch LCD TV:
Physical resolution :640*480(VGA), Audio power output:2*2W, Inside
power module AC input voltage:AC 100～240V,50/60Hz.Standby power
consuption ≤
Ⅱ、 Main feature
1、Radio frequency input
It can receive CATV signal.
2、AV input
Convenient for watching a DVD player,VCR,pickup camera or other
playback devices.
3、Scart input
Convenient of receiving a high quality component signal from a DVD
player.
4、YPbPr input
Capable of receiving the high definition YPbPr signal in
480i,480P,576i,576P,720P（50/60HZ）,1080i（50/60HZ）,and 1080P
（50/60HZ） formats.
5、Scart output
6、VGA input
a. Convenient to connect with a host computer.
b. Use as a data display terminal.
c. Connect the 3.5mm(diameter)audio jack to your computer’s soundcard
to listen to stereo sound transmitted from your home computer.
7、Program & child lock function
Capable of locking any program of the TV and the function button of
the front panel.
8、Timer function
9、Blue background with noise reduction
In AV、Scart and YPbPr modes, screen displays soft blue background
if there is no signal input.
10、 Multi Language on-screen display menu
Text and graphical user interface makes the menu operation
user-friendly.
11、 Power energy Saving mode(power management mode)
When used as PC display terminal without PC signal output, the LCD TV
will automatically power off within 30 Seconds and enter Power Energy
Saving Mode. It will automatically startup again when it receives a
signal from the PC.To start the TV manually with no signal press the
number buttons or【 】/【P+】/【P-】 on the remote control.
12、Plug-and-play
No additional software is needed when the product is used as computer
terminal display.
13、Automatic picture’s quality adjustment
14、No flicker, no radiation, greenness and health
15、Auto on as time is set
16、Zoom mode
Full-screen 、16:9、cinema、Subtitle
17、Legerity, convenient, low power consumption
18、Picture quality enhancement function
Dynamic skin color correct: improve distort color in picture, make
it near to real color.
Black level extension: darken the large part of black section to
enhance pictures contrast in the dim background
Color edge adjustment: increase the steep of color signal edge, make
the edge of color transition more clearly.
Brightness edge adjustment: increase edge gradient of brightness
signal, make the edge of picture more clearer
19、Super definition display panel
20、Dynamic comb filter
21、Headphones output
22、10 page teletext
Ⅲ. Circuit composition of the TV
The Europe LS03 chassis LCD TV is composed of regulating voltage
circuit、inverter Circuit 、RF circuit、video enhancement circuit、video
Processing circuit、Power amplifier circuit、VGA circuit、system control
circuit and key control circuit. The block diagram of circuit composition
is below:
Ⅳ. PCB assembly introduction
The Constitution of the PCB is easier than LS07 chassis, all the Signal
Processing are in Main board.
1、 Main board assembly
Main board Module is the main part of Signal Processing in LCD TV. The
input signal is converted into uniform digital signal which can be
identified by TFT under the control of system control circuit. Main board
module contains two parts of signal processing module: TDA9886
process analog audio and video circuit mainly, MST718 process VGA circuit、
signal format transform system control circuit mainly. The front module
can convert the video IF signal and audio IF signal from tuner into RGB
analog signal and audio signal, this part is named analog audio and video
decoding process. The RGB color from TDA9886 is received by MST718,then
MST718
accomplish A/D converting , output suitable digital color signal to
Drive circuit of TFT . 8051 Processor inside TDA9886 is responsible for
co-operation work of the each part of system, and respond to user
operation which is operated on control panel(key board Module).
2、 Key board assembly
It is composed of 7 function keys. the user can operate the LCD TV
conveniently by using this assembly.
3、 Remote control receiving board assembly
It is composed of a work indicator light and a remote receive head. The
user use the remote control box by this module can operate the LCD TV
conveniently and know the LCD TV work condition.
4、 Earphone output board assembly
It is composed of a earphone outlet, user can Listen by earphone
Liner voltage IC
conveniently.
5、 Inverter board assembly(include inverter circuit)
The function of the inverter is supply power to light tube in TFT , and
lighten the back lamp Unit of TFT module, so the user can see the image
on TFT.
PartⅡ: Function introduction about the main integrated
circuit
Ⅰ. Main ICs and components
Serial number Name model Main function
1 U4 MP1430DN-LF-Z
2 U8 PI5V330SQEX
3 U9 24LC21AT/SN
4 U23 24LC32AT/SN
5 U11 STV-8217
6 U15 TDA1517P
7 U14 AZ1117H-1.8TRE1
8 U13 AZ1117H-3.3TRE1
9 U19 TDA9886TS/V4
Video switch
EEPROM(save display
parameter information)
EEPROM（save user control
information）
Audio processor
Audio power amplifier
Low dropout voltage
regulator
Low dropout voltage
regulator
Analog signal
processor
10 U17 TDA5-E2I21RW2
Video Decoder
Analog Input
Color Engine
RF tuner
11 U22 MST718BE-LF
AD converter and format
transformer
Ⅱ. The function introduction of main IC
1 The MST718BE is a high quality ASIC for NTSC/PAL/SECAM LCD-TV
application. It receives analog NTSC/PAL/SECAM CVBS and S-Video inputs
from TV tuners, DVD or VCR sources, including weak and distorted signals,
as well as analog RGB input from GPS systems. Automatic gain control (AGC)
and 10-bit 3-channel A/D converters provide high resolution video
quantization. With automatic video source and mode detection,users can
easily switch and adjust variety of signal sources. Multiple internal
adaptive PLLs precisely extract pixel clock from video source and perform
sharp color demodulation. Built-in line-buffer supports adaptive 2-D
comb-filter, 2-D sharpening, and synchronization stabler in a condense
manner. The output format of MST718BE supports 8-bit TTL or LVDS digital
TFT-LCD modules.
MST518 FEATURES:
● Supports NTSC, PAL and SECAM video input formats
●2D NTSC and PAL comb-filter for Y/C separation of CVBS input
●Multiple CVBS and S-video inputs Supports Closed-caption and V-chip
●Supports Teletext 1.5
●ACC, AGC, and DCGC (Digital Chroma GainControl)
●Supports RGB input format from PC,camcorders and GPS
●Supports YCbCr inputs from conventional videosource and HDTV
●Supports SCART – RGB + Fast Blank
●Supports video input 480i, 480p, 576i, 576p,720p, 1080i; RGB input
resolution in 640x480,800x480, 800x600, 1024x768, and
1280x1024(SXGA)
●3-channel low-power 10-bit ADCs integration for YCbCr and RGB
●Supports RGB composite sync input (CSYNC),SOY, SOG, HSYNC, and VSYNC
●On-chip clock synthesizer and PLL
●Auto-position adjustment, auto-phase adjustment, auto-gain
adjustment, and auto-mode detection
●Brightness, contrast, saturation, and hue adjustment
●9-tap programmable multi-purpose FIR (Finite Impulse Response)
filter
●Differential 3-band peaking engine
●Vertical peaking
●Spatial noise reduction
●Luminance Transient Improvement (LTI)
Scaling Engine/Panel Interface
Miscellaneous
●Chrominance Transient Improvement (CTI)
●Black Level Extension (BLE)
●White Level Extension (WLE)
●Favor Color Compensation (FCC)
●3-channel gamma curve adjustment
●Independent 6 color of saturation, hue, and brightness control
●Supports digital panels up to 1366x768, and 1440x900
●Supports single/dual 8-bit LVDS panel outputs
●Supports 8-bit TTL panel output
●Supports various displaying modes
●Supports horizontal panorama scaling
●Built-in MCU
●3-wire serial bus interface for configuration setup
●Built-in step-down PWM circuits for input 2.5V
●Built-in internal OSD with 512 programmable fonts, 1、2 or 4 bit per
pixel color, 16-color palettes, and 12-bit color resolution
●Supports external OSD
●Support CVBS out
●Spread spectrum clocks
●Optional 3.3V / 5V output pads with programmable driving current
●128-pin PQFP package
MST718 pin function:
Analog Interface
Pin Name Pin Type Function Pin
VMID
VCLAMP
REFM
REFP
PRINP Analog Input Analog Pr Input of HDTV 7
PRINM Analog Input Reference Ground for Analog Pr Input o f HDTV 8
PBINP Analog Input Analog Pb Input of HDTV 9
PBINM Analog Input Reference Ground for Analog Pb Input of HDTV 10
SOY Analog Input Sync-on-Y slicer input 11
YINP Analog Input Analog Y Input of HDTV 12
YINM Analog Input Reference Ground for Analog Y Input of HDTV 13
BINP Analog Input Analog B Input of VGA 14
BINM Analog Input Reference Ground for Analog B Input of VGA 15
SOGIN Analog Input Sync-on-Green slicer input 16
Mid-Scale Voltage Bypass 2
CVBS/YC Mode Clamp Voltage Bypass 3
Internal ADC Bottom De-coupling Pin 4
Internal ADC Top De-coupling Pin 5
GINP Analog Input Analog G Input of VGA 17
GINM Analog Input Reference Ground for Analog G Input of VGA 18
RINP Analog Input Analog R Input of VGA 19
RINM Analog Input Reference Ground for Analog R Input of VGA 20
C1INP Analog Input Analog Chroma Input for TV S-Video1 / Analog
Composite Input of TV CVBS4
C1INM Analog Input Reference Ground for Analog Chroma Input of TV
S-Video1 / Analog Composite Input of TV CVBS4
YS1INP Analog Input
YS1INM Analog Input Reference Ground for Analog Luma Input of TV
C2INP Analog Input Analog Chroma Input for TV S-Video2 26
C2INM Analog Input
YS2INP Analog Input Analog Luma Input of TV S-Video2 28
YS2INM Analog Input
CVBS1P Analog I nput Analog Composite Input for TV CVBS1 30
CVBS1M Analog Input
CVBS2P Analog I nput Analog Composite Input for TV CVBS2 32
CVBS2M Analog Input
Analog Luma Input o f TV S-Video1 / Analog
Composite Input of TV CVBS3
S-Video1 / Analog Composite Input of TV CVBS3
Reference Ground for Analog Chroma Input of TV
S-Video2
Reference Ground for Analog Luma Inp ut of TV
S-Video2
Reference Ground for Analog Composite Input of
TV CVBS1
Reference Ground for Analog Composite Input of
TV CVBS2
22
23
24
25
27
29
31
33
Pin Name Pin Type Function Pin
VREXT_CDAC Analog Input
HSYNCIN1 Schmitt Trigger Input
w/ 5V-tolerant
VSYNCIN1
HSYNCIN2 Schmitt Trigger Input
VSYNCIN2 Schmitt Trigger Input
Schmitt Trigger Input
w/ 5V-tolerant
w/ 5V-tolerant
w/ 5V-tolerant
Reference Current Generator, 820 ohm to
Ground
HSYNC / Composite Sync for VGA Input 1 125
VSYNC for VGA Input 1 124
HSYNC / Composite Sync for VGA Input 2 123
VSYNC for VGA Input 2 122
116
Digital Panel Output Interface
Pin Name Pin Type Function Pin
CLKO Output Display Clock Output 77
DEO Output Display Enable Output 78
VSYNCO Output Vertical Sync Output 79
HSYNCO Output Horizontal Sync Output 80
BOUT[7]/LVB0M Output Blue channel Output [7] / LVDS B-Link Channel 0
Negative Differential Data Output
BOUT[6]/LVB0P Output Blue channel Output [6] / LVDS B-Link Channel 0
Positive Differential Data Output
BOUT[5]/LVB1M Output
BOUT[4]/LVB1P Output Blue channel Output [4] / LVDS B-Link Channel 1
BOUT[3]/LVB2M Output
BOUT[2]/LVB2P Output Blue channel Output [2] / LVDS B-Link Channel 2
BOUT[1]/LVBCK
M
BOUT[0]/LVBCK
P
GOUT[7]/LVB3M Output Gre en channel Output [7] / LVDS B-Link Channel 3
GOUT[6]/LVB3P Output
GOUT[5:4] Output Gree n channel Output [5:4] 97, 96
Output Blue channel Output [1] / LVDS B-Link Negative
Output
Blue channel Output [5] / LVDS B-Link Channel 1
Negative Differential Data Output
Positive Differential Data Output
Blue channel Output [3] / LVDS B-Link Channel 2
Negative Differential Data Output
Positive Differential Data Output
Differential Clock Output
Blue channel Output [0] / LVDS B-Link Positive
Differential Clock Output
Negative Differential Data Output
Green channel Output [6] / LVDS B-Link Channel 3
Positive Differential Data Output
108
107
106
105
104
103
102
101
99
98
Pin Name Pin Type Function Pin
GOUT[3]/LV
A0M
GOUT[2]/LV
A0P
GOUT[1]/LV
A1M
GOUT[0]/LV
A1P
ROUT[7:6] Output Red channel Output [7:6] 91, 90
ROUT[5]/LV
A2M
ROUT[4]/LV
A2P
ROUT[3]/LV
ACKM
ROUT[2]/LV
ACKP
Output
Output Green channel Output [2] / LVDS A-Link Channel 0
Output Green channel Output [1] / LVDS A-Link Channel 1
Output Green channel Output [0] / LVDS A-Link Channel 1
Output Red channel Output [5] / LVDS A-Link Chan nel 2
Output Red channel Output [4] / LVDS A-Link Chan nel 2
Output Red channel Output [3] / LVDS A-Link Negative
Output Red channel Output [2] / LVDS A-Link Positive
Green channel Output [3] / LVDS A-Link Channel 0
Negative Differential Data Output
Positive Differential Data Output
Negative Di fferential Data Output
Positive Differential Data Output
Negative Differential Data Output
Positive Differential Data Output
Differential Clock Output
Differential Clock Output
95
94
93
92
89
88
87
86
ROUT[1]/LV
A3M
ROUT[0]/LV
A3P
Output Red channel Output [2] / LVDS A-Link Chan nel 3
Negative Differential Data Output
Output Red channel Output [0] / LVDS A-Link Channel 3
Positive Differential Data Output
85
84
External OSD Interface
Pin Name Pin Type Function Pin
OSDR/GPIO
_P30
OSDG/GPIO
_P31
OSDB/GPIO_
P32
FB/GPIO_P3
3
I/O w/
5V-tolerant
I/O w/
5V-tolerant
I/O w/
5V-tolerant
I/O w/
5V-tolerant
External OSD R-channel Input / General Purpose
Input/Output; 4mA driving strength
External OSD G-channel Input / General Purpose
Input/Output; 4mA driving strength
External OSD B-channel Input / General Purpose
Input/Output; 4mA driving strength
External Fast-Blank Input / General Purpose
Input/Output; 4mA driving strength
Switching Power and PWM Interface
73
74
75
76
Pin Name Pin Type Function Pin
PWMOUT2 Output Switching Pulse Output for DC-DC Converter 38
FB2 Analog Input Error Voltage Feedback Input Pin for PWM2;
voltage = 1.2V
SENSE2 Analog Input Sense Circuit Connection for PWM2 40
PWMOUT1 Output Switching Pulse Output for DC-DC Converter 41
FB1 Analog Input Error Voltage Feedback Input Pin for PWM1;
voltage = 1.2V
SENSE1 Analog Input Sense Circuit Connection for PWM1 43
PGOOD Output Power Good Indicator 44
39
42
Internal MCU Interface with Serial Flash Memory
Pin Name Pin Type Function Pin
SAR2 Analog Input SAR Low Speed ADC Input 2 49
SAR1 Analog Input SAR Low Speed ADC Input 1 48
SAR0 Analog Input SAR Low Speed ADC Input 0 47
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