Changhong LS03-U, LS02(AX3268) Schematic

LCD TELEVISION

SERVICE MANUAL

CHASSIS LS03（U）

Please read this manual carefully before service.

1

CONTENTS

PartⅠ:Specification, feature and Composition ……………………………………3
PartⅡ: Function introduction about the main integrated circuit ………………..6
PartⅢ: Signal Processing Flow chart ….………………………………………….18
PartⅣ: Typical troubleshooting processing flowchart …………………………..21
Annex: Circuit schematic diagram

2

PartⅠ: Specification , feature and Composition

Ⅰ. 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、S-Video 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,
1080i formats.
5、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.
6、Program & child lock function
Capable of locking any program of the TV and the function button of the front panel.
7、Timer function
8、Blue background with noise reduction
In TV，AV，S-Video，YPbPr and PC modes, screen displays soft blue background ,
if there is no signal input.
9、 Multi Language on-screen display menu
Text and graphical user interface makes the menu operation user-friendly.
10、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.
11、Plug-and-play
No additional software is needed when the product is used as computer
terminal display.
12、Automatic picture’s quality adjustment
13、No flicker, no radiation, greenness and health
14、Auto on as time is set
15、Zoom mode（for19”,22”Model）
Full-screen 、16:9、cinema、Subtitle
16、Legerity, convenient, low power consumption
17、Picture quality enhancement function
Dynamic skin color correct: improve distort color in picture, make it near to real
color.

3

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
18、Super definition display panel
19、Dynamic comb filter
20、Headphones output(not include 02 series)

Ⅱ. Circuit composition of the TV
The 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:

RF Input

TDA9886

S-Video input

To panel

input

video input

input

input

Vedio

HD/YPbPr

YPbPr audio

PC Sound

PC

P15V330

LA72702

PT2314

MST718BU

TDA1517 Loudhailer

Earphone

Power Intverter

Ⅲ. PCB assembly introduction
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.
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

4

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(not include 02 series)
It is composed of a earphone outlet, user can Listen by earphone 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.

5

PartⅡ: Function introduction about the main integrated

circuit

. Main ICs and componentsⅠ

Serial
number

1 U4 MP1430DN-LF-Z Liner voltage IC
2 U8 PI5V330SQEX Video switch
3 U9 24LC21AT/SN EEPROM(save display

4 U23 24LC32AT/SN EEPROM（save user

5 U16 PT2314 Audio processor
6 U15 TDA1517P Audio power amplifier
7 U19 TDA9886TS/V4 single and

8 U17 TAF5-C2IP1RW RF tuner
9 U22 MST718BU Processor with Video

10 U21 LA72702NVA

. The function introduction of main ICⅡ

1 The MST718BU 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 MST718BU supports 8-bit TTL or LVDS digital TFT-LCD
modules.
MST718 FEATURES:

Video Decoder

· 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)

Name model Main function

parameter information)

control information）

multistandard
alignment-free
IF-PLL demodulators

Decoder

US TV BTSC Decoder

6

Analog Input

·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

Color Engine

·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)

·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

Scaling Engine/Panel Interface

·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

Miscellaneous

·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

7

Pin Name Pin Type Function Pin

VMID

VCLAMP

REFM

REFP

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

PRINP Analog Input Analog Pr Input of HDTV 7

PRINM Analog Input

Reference Ground for Analog Pr Input of
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

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

C1INP Analog Input Analog Chroma Input for TV S-Video1 /

Reference Ground for Analog R Input of
VGA

20

22

Analog Composite Input of TV CVBS4

C1INM Analog Input Reference Ground for Analog Chroma Input

23
of TV S-Video1 / Analog Composite Input of
TV CVBS4

YS1INP Analog Input Analog Luma Input of TV S-Video1 / Analog

24
Composite Input of TV CVBS3

YS1INM Analog Input Reference Ground for Analog Luma Input of

25
TV S-Video1 / Analog Composite Input of
TV CVBS3

C2INP Analog Input Analog Chroma Input for TV S-Video2 26

C2INM Analog Input

Reference Ground for Analog Chroma Input
of TV S-Video2

27

YS2INP Analog Input Analog Luma Input of TV S-Video2 28

YS2INM Analog Input

Reference Ground for Analog Luma Input of
TV S-Video2

29

CVBS1P Analog Input Analog Composite Input for TV CVBS1 30

8

CVBS1M Analog Input

Reference Ground for Analog Composite
Input of TV CVBS1

31

CVBS2P Analog Input Analog Composite Input for TV CVBS2 32

CVBS2M Analog Input

Reference Ground for Analog Composite
Input of TV CVBS2

33

Pin Name Pin Type Function Pin

VREXT_CDAC Analog Input

HSYNCIN1 Schmitt Trigger

Input w/

Reference Current Generator, 820 ohm
to Ground
HSYNC / Composite Sync for VGA
Input 1

116

125

5V-tolerant

VSYNCIN1 Schmitt Trigger

VSYNC for VGA Input 1 124
Input w/
5V-tolerant

HSYNCIN2 Schmitt Trigger

Input w/

HSYNC / Composite Sync for VGA

Input 2

123

5V-tolerant

VSYNCIN2 Schmitt Trigger

VSYNC for VGA Input 2 122
Input w/
5V-tolerant

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]/LVB
0M
BOUT[6]/LVB
0P
BOUT[5]/LVB
1M
BOUT[4]/LVB
1P
BOUT[3]/LVB
2M
BOUT[2]/LVB
2P
BOUT[1]/LVB
CKM

9

Output Blue channel Output [7] / LVDS B-Link Channel

0 Negative Differential Data Output

Output Blue channel Output [6] / LVDS B-Link Channel

0 Positive Differential Data Output

Output Blue channel Output [5] / LVDS B-Link Channel

1 Negative Differential Data Output

Output Blue channel Output [4] / LVDS B-Link Channel

1 Positive Differential Data Output

Output Blue channel Output [3] / LVDS B-Link Channel

2 Negative Differential Data Output

Output Blue channel Output [2] / LVDS B-Link Channel

2 Positive Differential Data Output

Output Blue channel Output [1] / LVDS B-Link Negative

Differential Clock Output

108

107

106

105

104

103

102

BOUT[0]/LVB
CKP
GOUT[7]/LVB
3M
GOUT[6]/LVB
3P

Output Blue channel Output [0] / LVDS B-Link Positive

Differential Clock Output

Output Green channel Output [7] / LVDS B-Link

Channel 3 Negative Differential Data Output

Output Green channel Output [6] / LVDS B-Link

Channel 3 Positive Differential Data Output

101

99

98

GOUT[5:4] Output Green channel Output [5:4] 97, 96

Pin Name Pin Type Function Pin

GOUT[3]/
LVA0M

GOUT[2]/
LVA0P
GOUT[1]/
LVA1M
GOUT[0]/
LVA1P

Output

Green channel Output [3] / LVDS A-Link
Channel 0 Negative Differential Data Output

Output Green channel Output [2] / LVDS A-Link

Channel 0 Positive Differential Data Output

Output Green channel Output [1] / LVDS A-Link

Channel 1 Negative Differential Data Output

Output Green channel Output [0] / LVDS A-Link

Channel 1 Positive Differential Data Output

95

94

93

92

ROUT[7:6] Output Red channel Output [7:6] 91, 90

ROUT[5]/L
VA2M
ROUT[4]/L
VA2P
ROUT[3]/L
VACKM
ROUT[2]/L
VACKP
ROUT[1]/L
VA3M
ROUT[0]/L
VA3P

Output Red channel Output [5] / LVDS A-Link Channel

2 Negative Differential Data Output

Output Red channel Output [4] / LVDS A-Link Channel

2 Positive Differential Data Output

Output Red channel Output [3] / LVDS A-Link Negative

Differential Clock Output

Output Red channel Output [2] / LVDS A-Link Positive

Differential Clock Output

Output Red channel Output [2] / LVDS A-Link Channel

3 Negative Differential Data Output

Output Red channel Output [0] / LVDS A-Link Channel

3 Positive Differential Data Output

89

88

87

86

85

84

External OSD Interface

Pin Name Pin Type Function Pin

OSDR/GPI
O_P30

OSDG/GPI
O_P31

OSDB/GPI
O_P32

10

I/O w/
5V-toleran
t
I/O w/
5V-toleran
t
I/O w/
5V-toleran
t

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

73

74

75

FB/GPIO_
P33

I/O w/
5V-toleran
t

External Fast-Blank Input / General Purpose
Input/Output; 4mA driving strength

76

Switching Power and PWM Interface

Pin Name Pin Type Function Pin

PWMOUT2 Output

FB2 Analog Input Error Voltage Feedback Input Pin for

Switching Pulse Output for DC-DC
Converter

38

39

PWM2; voltage = 1.2V

SENSE2 Analog Input Sense Circuit Connection for PWM2 40

PWMOUT1 Output

FB1 Analog Input Error Voltage Feedback Input Pin for

Switching Pulse Output for DC-DC
Converter

41

42

PWM1; voltage = 1.2V

SENSE1 Analog Input Sense Circuit Connection for PWM1 43

PGOOD Output Power Good Indicator 44

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

SCK Output SPI Interface Sampling Clock 52

SDI Output SPI Interface Data-In 53

SDO Input w/ 5V-tolerant SPI Interface Data-Out 54

CSN Output SPI Interface Chip Select 55

GPIO_P0
0-GPIO_
P07

I/O w/ 5V-tolerant

General Purpose Input/Output; 4mA
driving strength

58-64, 83

INT Input Interrupt Input for IR Receiver 65

SDA I/O w/ 5V-tolerant 3-Wire Serial Bus Data 66

SCL Input w/ 5V-tolerant 3-Wire Serial Bus Clock 67

POWER_
ON_RST
N/CS

Input w/ 5V-tolerant

Power On Reset Signal/Chip Selection
for 3-wire Serial

68

Misc. Interface

Pin Name Pin Type Function Pin

RESET Schmitt Trigger

Hardware Reset; active high 72

Input w/

11

5V-tolerant

XIN Analog Input Crystal Oscillator Input

121

XOUT Analog Output Crystal Oscillator Output 120

GPIO_P24
/PWMD3

Output General Purpose Input/Output; 4mA

driving

56

strength/ Pulse Width Modulation
Output;
4mA driving strength

Pin Name Pin Type Function Pin

GPIO_P25
/PWMD4

Output General Purpose Input/Output;

4mA driving strength/ Pulse Width

57

Modulation Output; 4mA driving strength

PWMD2 Output

PWMD1 Output

Pulse Width Modulation Output;
4mA driving strength
Pulse Width Modulation Output;
4mA driving strength

70

71

INT_OUT Output Mode Detection Interrupt Output 100

CVBSO1
/CVBSO2

Output

MCUSEL Input Embedded MCU selection.

Analog Composite Output for
TV CVBS1/CVBS2

34, 115

109

0: MCU on. 1: MCU off.

Power Pins

Pin Name Pin Type Function Pin

AVDD_ADC 2.5V Power ADC Power 6, 21

AVDD_GMC 5V Power GMC Power 35

AVDD_PWM 5V Power PWM Power 37

AVDD_OPLL 2.5V Power OPLL Power 113

AVDD_CDAC 2.5V Power Current DAC Power 117

AVDD_XTAL 5V Power XTAL Power 118

AVDD_MPLL 2.5V Power MPLL Power 127

VDDC 2.5V Power Digital Core Power 50, 110

VDDP 3.3V/5V Power

Digital Input/Output
Power

46, 82

GND Ground Ground 1, 36, 45, 51, 69, 81,

111, 112, 114, 119,
126, 128

12

2 TDA9886 introduction:
The TDA9885 is an alignment-free multistandard (PAL and NTSC) vision and sound
IF signal PLL demodulator for negative modulation only and
FM processing.The TDA9886 is an alignment-free multistandard (PAL, SECAM and
NTSC) vision and sound IF signal PLL demodulator for positive and negative
modulation,including sound AM and FM processing.

FEATURES

· 5 V supply voltage

· Gain controlled wide-band Vision Intermediate Frequency (VIF) amplifier,
AC-coupled

· Multistandard true synchronous demodulation with active carrier regeneration: very
linear demodulation,good intermodulation figures, reduced harmonics, and
excellent pulse response

· Gated phase detector for L and L-accent standard

· Fully integrated VIF Voltage Controlled Oscillator(VCO),
alignment-free, frequencies switchable for all negative and positive modulated
standards via I2C-bus

· Digital acquisition help, VIF frequencies of 33.4, 33.9,38.0, 38.9, 45.75, and 58.75
MHz

· 4 MHz reference frequency input: signal from Phase-Locked Loop (PLL) tuning
system or operating as crystal oscillator

· VIF Automatic Gain Control (AGC) detector for gain control, operating as peak
sync detector for negative modulated signals and as a peak white detector for
positive modulated signals

· External AGC setting via pin OP1

· Precise fully digital Automatic Frequency Control (AFC) detector with 4-bit
digital-to-analog converter, AFC bits readable via I2C-bus

· TakeOver Point (TOP) adjustable via I2C-bus or alternatively with potentiometer

· Fully integrated sound carrier trap for 4.5, 5.5, 6.0, and 6.5 MHz, controlled by
FM-PLL oscillator

· Sound IF (SIF) input for single reference Quasi Split Sound (QSS) mode, PLL
controlled

· SIF-AGC for gain controlled SIF amplifier, single reference QSS mixer able to
operate in high performance single reference QSS mode and in
intercarrier mode, switchable via I2C-bus

· AM demodulator without extra reference circuit

· Alignment-free selective FM-PLL demodulator with high linearity and low noise

· I2C-bus control for all functions

· I2C-bus transceiver with pin programmable Module Address (MAD)

· Four I2C-bus addresses via MAD.

TDA9886 pin function:

SYMBOL PIN DESCRIPTION

13

VIF1 1 VIF differential input 1
VIF2 2 VIF differential input 2
n.c. - not connected
OP1 3 output port 1; open-collector
FMPLL 4 FM-PLL for loop filter
DEEM 5 de-emphasis output for capacitor
AFD 6 AF decoupling input for capacitor
DGND 7 digital ground
n.c. - not connected
AUD 8 audio output

TOP 9

tuner AGC TakeOver Point (TOP) for resistor

adjustment
SDA 10 I2C-bus data input and output
SCL 11 I2C-bus clock input

SIOMAD 12

sound intercarrier output and MAD select with

resistor
n.c. - not connected
n.c. 13 not connected
n.c. - not connected
TAGC 14 tuner AGC output
REF 15 4 MHz crystal or reference signal input
VAGC 16 VIF-AGC for capacitor
n.c. - not connected
CVBS 17 composite video output
n.c. - not connected
AGND 18 analog ground
VPLL 19 VIF-PLL for loop filter
VP 20 supply voltage
AFC 21 AFC output
OP2 22 output port 2; open-collector
n.c. - not connected

SIF1 23

SIF2 24

SIF differential input 1 and MAD select with

resistor

SIF differential input 2 and MAD select with

resistor
n.c. - not connected
n.c. - not connected

14

3 PT2314 introduction

Description

PT2314 is a four-channel input digital audio processor utilizing CMOS Technology.
Volume, Bass, Treble and
Balance are incorporated into a single chip. Loudness Function and Selectable Input
Gain are also provided to
build a highly effective electronic audio processor having the highest performance
and reliability with the least
external components. All functions are programmable using the I2C Bus. The pin
assignments and application
circuit are optimized for easy PCB layout and cost saving advantage for audio
application.

Features

 CMOS Technolog
 Least External Components
 Treble and Bass Control
 Loudness Function
 4 Stereo Inputs with Selectable Input Gain
 Input/Output for External Noise Reduction System/Equalizer
 2 Independent Speaker Controls for Balance Control
 Independent Mute Function
 Volume Control in 1.25 dB/step
 Low Distortion
 Low Noise and DC Stepping
 Controlled by I2C Bus Micro-Processor Interface
 Available in 28 Pins, DIP/SO Package

Applications

 Car Stereo (Audio)

 Hi-Fi Audio System

15

4 LA72702NVA introduction

Application
US TV BTSC Decoder
Characteristics
With SIF circuit、alignment-free* STEREO channel separation
* When Base Band signal input, separation is adjusted by input level.
Dual Slave address(80h,84h)
Functions
SIF FM-Demodulator
STEREO decoder
dbx Noise Reduction
STEREO detection
STEREO detection sensitivity change function
SAP demodulator
SAP detection
SAP output select 2-levels
SAP detection sensitivity change function

16

5 TDA1517 introduction:
The TDA1517 is an integrated class-B dual output amplifier in a plastic single in-line
medium power package with fin (SIL9MPF), a plastic rectangular-bent single in-line
medium power package with fin (RBS9MPF) or a plastic heat-dissipating dual in-line
package (HDIP18). The device is primarily developed for multi-media applications.

FEATURES

· Requires very few external components

· High output power

· Fixed gain

· Good ripple rejection

· Mute/standby switch

· AC and DC short-circuit safe to ground and VP

· Thermally protected

· Reverse polarity safe

· Capability to handle high energy on outputs (VP = 0 V)

· No switch-on/switch-off plop

· Electrostatic discharge protection.

TDA1517 pin function:

SYMBOL PIN DESCRIPTION

-INV1 1 non-inverting input 1
SGND 2 signal ground

17

SVRR 3 supply voltage ripple

rejection output
OUT1 4 output 1
PGND 5 power ground
OUT2 6 output 2
VP 7 supply voltage
M/SS 8 mute/standby switch input

-INV2 9 non-inverting input 2

18

PartⅢ: Signal Processing Flow chart

This chapter mainly introduces analog signals process、video intensify
process、TV system control process、TV supply system.
1、 IF/RF process
Completed by TAF5-E2I21RW2 RF tuner, output IF signal.
The Function of RF tuner is below:

Pin symbol function
1 AGC Auto gain control voltage

2 TU The TV do not connect

3 ADD ground
4 SCL

5 SDA
6 BM +5V power supply

7 BM +5V power supply

8 NC Not connected

9 BTL

10 NC Not connected
11 IF IF signal output
2、 Image and sound process
TDA9886 chip receives the IF signal separated from SAW filter, detects
and decodes to output CVBS analog signals from the 17 pin and TV-SIFP signal
from12 pin. CVBS analog signals is decoded inside of MST718BU chip. TV-SIFP
signal is decoded inside of LA 72702NV and PT2314 chip, then output the main
channel L、R audio signal from 24,23 pin.
3、 Digital signal process
The MST718BU receives analog NTSC/PAL-M/PAL-N CVBS and S-Video inputs.
It finishes the pixels ratio converting of input video signal, the image auto
optimization process ,then process via memory buffer, scaler, chroma matrix
circuitm, chroma look-up table, chroma space gain, etc. Output corresponding
standard physical resolution digital color signal and corresponding sync, clock signal
to TFT, control the TFT to display image correctly.

I2C bus（clock ）
I2C bus（data ）

+32V power supply，form 0～32V tune
voltage

19

4、TV power supply system:

F1

12Vu

U5

4435

L44

U1

IRF7314

On/Off

U4

MSP1430

Vcc-Panel

On/Off

12VA

5V-DC

Panel

U15

TDA1517P

倍压

U2

7808

U5

4435

On/Off

L11

GMC-5V

L16

PWM-5V

L14

VAX-5V

U7

AMS1117.2.5

Inverter

U17

33V

TUNER

9VA

PT2314

Q19

2SC388

Vcc-Panel

MST718

MST718

MST718

2.5V

U16

U22

U22

U22

L15

Panel

DPL-2.5V

U22

MST718

On/Off

U1

IRF7314

U6

AMS1117-3.3

U23

24C32

Q8

3904

L10

L17

L13

STV82X6-5V

3.3V

BL-ON/OFF

ADC-2.5V

MPL-2.5V

CDAC-2.5V

L2

L31

U5

Vcc-Panel

4435

On/Off

L12

VDP-3.3V

MST718

MST718

MST718

5VA

U22

U22

U22

L39

L38

Panel

U24

PS25LV040

U22

MST718

U17

TUNER

U19

TUNER

U21

LA72702

(for separated power supply unit)

20

L32

12Vu

U5

4435

Vcc-Panel

On/Off

Panel

IRF7314

On/Off

U1

12VA

5V-DC

On/Off

U15

TDA1517P

倍压

U2

7808

U5

4435

On/Off

L11

GMC-5V

L16

PWM-5V

L14

VAX-5V

U7

AMS1117.2.5

U1

IRF7314

U17

33V

TUNER

U16

9VA

PT2314

Q19

2SC388

Vcc-Panel

U22

MST718

U22

MST718

U22

MST718

L15

2.5V

STV82X6-5V

L10

L17

L13

CDAC-2.5V

Panel

DPL-2.5V

ADC-2.5V

MPL-2.5V

L2

MST718

MST718

MST718

MST718

5VA

U22

U22

U22

U22

L39

L38

U17

TUNER

U19

TUNER

U6

AMS1117-3.3

U23

24C32

Q8

3904

for(for integrated power supply unit)

21

3.3V

BL-ON/OFF

L31

U5

4435

L12

Vcc-Panel

On/Off

VDP-3.3V

U21

LA72702

Panel

U24

PS25LV040

U22

MST718

PartⅣ: Typical troubleshooting processing flowchart

. Typical troubleshooting flowchartⅠ

1、No anything(haven’t sound ,haven’t picture, haven’t indicator
light),and no respondence to key，remote control.

No answer,no respondence to
key and remote control button

Is outside adapter(or

NO

repair or change
adapter

inside)
output 12V normal?

YES

The connection of
Main board and key
board ,remote control
board is reliable or not?

NOYES

Connect the wire
again

Check U4,U6,U7
Outside circuit

Is U4,U6,U7 output
port voltage normal?

NO YES

Check each supply power pins voltage of
U4,U6,U7 output to U22 are correct or not?

YES NO

Change U22

1、check peripheral parts of supply
power pin .
2、check the soldered joint is OK or
not.

22

2、 Have sound no picture, indicator light work normally

indicator light work, but black screen
when pressing down the power supply

Observe back lamp is on
or off

Check U4,U6,U7Outside
circuit

YES

U4,U6,U7 output voltage
is normal or not?

NO

Check each supply power pins voltage of
U4,U6,U7 output to U22 are correct or not?

Change U22

NO

Check inverter supply power
voltage and connect line

YES

YES NO

1、check peripheral parts of supply
power pin .
2、check the soldered joint is OK or not.

23

3、White screen: The reason of the troubleshoot is the signal electrode electrode
haven’t working voltage. The TFT is always in transparent condition, so the whole
screen is in white raster.

VLCD of screen socket
CON3(CON4) on main board
is normal or not?

NO YES

Check Q5,U5,L6,L7,L8
etc related parts

Check PCB copper
connect line

Check the soldering of
screen socket on
main board is OK or not?

YES NO

Switch signal source, use
the oscillograph to check
the signal input or not

YES NO

Check U22 peripheral
circuit is normal or
not ,change the trouble
parts.

Patch solder

24