Xoceco LC-26HU36UAE, LC-26HU36S, LC-37HU36S, LC-37HU36UAE Schematic

LCD TELEVISION

LC-(26-37)HU36S

CONTENTS

Safety instructions………………………………………………………………………..…

Adjustment instruction …………………………….…….…………………………….…

working principle analysis……………………………….………….…………………….

block diagram…………………………………..……………………….………………….

IC block diagram………………………………………………………………………..……

Wiring diagram ……………………………………………………………..……………...

Troubleshooting guide ………………………………………………………………..……

Schematic diagram…………………………………………………………………………..

APPENDIX-A: Assembly list

APPENDIX-B: Exploded view

Attention: This service manual is only for service personnel to take reference with. Before

servicing please read the following points carefully.

Safety precautions

1. Instructions

Be sure to switch off the power supply before replacing or welding any components or inserting/plugging in connection wire Anti static measures to be taken (throughout the entire production process!): a) Do not touch here and there by hand at will; b) Be sure to use anti static electric iron; c) It’s a must for the welder to wear anti static gloves. Please refer to the detailed list before replacing components that have special safety requirements. Do not change the specs and type at will.

2. Points for attention in servicing of LCD

2.1 Screens are different from one model to another and therefore not interchangeable. Be sure to use the screen of the original model for replacement.

2.2 The operation voltage of LCD screen is 700-825V. Be sure to take proper measures in protecting yourself and the machine when testing the system in the course of normal operation or right after the power is switched off. Please do not touch the circuit or the metal part of the module that is in operation mode. Relevant operation is possible only one minute after the power is switched off.

2.3 Do not use any adapter that is not identical with the TV set. Otherwise it will cause fire or damage to the set.

2.4 Never operate the set or do any installation work in bad environment such as wet bathroom, laundry, kitchen, or nearby fire source, heating equipment and devices or exposure to sunlight etc. Otherwise bad effect will result.

2.5 If any foreign substance such as water, liquid, metal slices or other matters happens to fall into the module, be sure to cut the power off immediately and do not move anything on the module lest it should cause fire or electric shock due to contact with the high voltage or short circuit.

2.6 Should there be smoke, abnormal smell or sound from the module, please shut the power off at once. Likewise, if the screen is not working after the power is on or in the course of operation, the power must be cut off immediately and no more operation is allowed under the same condition.

2.7 Do not pull out or plug in the connection wire when the module is in operation or just after the power is off because in this case relatively high voltage still remains in the capacitor of the driving circuit. Please wait at least one minute before the pulling out or plugging in the connection wire.

2.8 When operating or installing LCD please don’t subject the LCD components to bending, twisting or extrusion, collision lest mishap should result.

2.9 As most of the circuitry in LCD TV set is composed of CMOS integrated circuits, it’s necessary to pay attention to anti statics. Before servicing LCD TV make sure to take anti static measure and ensure full grounding for all the parts that have to be grounded.

2.10 There are lots of connection wires between parts behind the LCD screen. When servicing or moving the set please take care not to touch or scratch them. Once they are damaged the screen

would be unable to work and no way to get it repaired. If the connection wires, connectors or components fixed by the thermotropic glue need to disengage when service, please soak the thermotropic glue into the alcohol and then pull them out in case of dagame.

2.11 Special care must be taken in transporting or handling it. Exquisite shock vibration may lead to breakage of screen glass or damage to driving circuit. Therefore it must be packed in a strong case before the transportation or handling.

2.12 For the storage make sure to put it in a place where the environment can be controlled so as to prevent the temperature and humidity from exceeding the limits as specified in the manual. For prolonged storage, it is necessary to house it in an anti-moisture bag and put them altogether in one place. The ambient conditions are tabulated as follows:

Temperature Scope for operation 0 ~ +50 oC

Scope for storage -20 ~ +60 oC

Humidity Scope for operation 20% ~ 85%

Scope for storage 10% ~ 90%

2.13 Display of a fixed picture for a long time may result in appearance of picture residue on the screen, as commonly called “ghost shadow”. The extent of the residual picture varies with the maker of LCD screen. This phenomenon doesn’t represent failure. This “ghost shadow” may remain in the picture for a period of time (several minutes). But when operating it please avoid displaying still picture in high brightness for a long time.

3. Points for attention during installation

3.1 The front panel of LCD screen is of glass. When installing it please make sure to put it in place.

3.2 For service or installation it’s necessary to use specified screw lest it should damage the screen.

3.3 Be sure to take anti dust measures. Any foreign substance that happens to fall down between the screen and the glass will affect the receiving and viewing effect

3.4 When dismantling or mounting the protective partition plate that is used for anti vibration and insulation please take care to keep it in intactness so as to avoid hidden trouble.

3.5 Be sure to protect the cabinet from damage or scratch during service, dismantling or mounting.

Alignment instructions

1. Test equipment

PM5518 (video signal generator) VG-849 (VGA signal generator) CA210 (white balancer)

2 Alignment flow-chart

The alignment flow-chart is shown as fig-1

Check DDC, HDCP KEY, FLASH and POWER control IC

Combined test for general assembly

Factory initialization setup

IF channel voltage of TV and AGC voltage adjustment

White balance adjustment

Fig-1 adjustment flow-chart

3 Unit adjustments

Connect all the boards according to wiring diagram, connect with power and observe the display. Method for entering factory menu: press “INPUT”, “2”, “5”, ”8” and “0” in turn to enter factory menu; press “CH+” and “CH-” to select adjustment items and press “VOL+” and “VOL-” to adjust value items, press “MENU” continuously to exit.

3.1 Initialization Enter factory menu, select “OPTION” and “HOTEL OPTION” sub-menu, adjustment of items to see table1.

Table1 sub-menu adjustment

Items Preset Introduce

HOTEL 0 1: HOTEL OPTION of factory menu is optional

0: HOTEL OPTION of factory menu is not optional

LOGO 1 1: display LOGO in no signal or turn on

0: no LOGO display

ADC PRESCALE 00A Adjust according different power consumption

SIF PRESCALE 000 Adjust according different power consumption

Performance check

Preset ex-factory

BACK LIGHT 28 Adjust according different screen

ALL COLOR 1 1: white balance of each channel auto offset based on the HDMI white

balance

0: white balance of each channel adjust the offset base separately

ISP 0 0: no unit upgrade on the assembly line

1: unit upgrade on the assembly line

NO STANDY 00 01: turn on; 00: memory function of turn on; 10: standby

INIT VOLUME 0-100 Volume of turn on

INIT CHANNEL 1-200 Channel of turn on

INIT SRC Source Source of turn on

EEPROM-MEMORAY

RECALL

> EEPROM Initialization (operate when EEPROM data chaos)

3.2 Adjustment for AFT voltage and AGC voltage of IF channel in TV

3.2.1 IF AFC adjustment Disconnect J401(B face), input 38.9MHz PAL signal of 80dB from J401 near the socket, Adjust

L404 to value 0.9V of TP402. Enter factory menu, adjust TDA4470 from BG to LL, input 33.9MHz SECAM signal of 80dB, adjust RP402 to value 0.9V of TP402, then wed J401.

3.2.2 IF AGC adjustment

Input 184.25MHz RF signal of 60DB from RF terminal, adjust RP401 to value 4V of TP404 and there should be no obvious snowy picture. Increase the signal to 90DBV and it should be display normally and no obvious noise.

3.3 White balance adjustment

3.3.1 white balance adjustment of HDMI

a. Input VG-848 signal from HDMI: TIMING854(800* 600/60Hz) and eighth level gray-scale

signal of PAT920. Use color analyzer CA210 to adjust white balance.

b. Enter submenu of COLOR TEMP., Select 9300k of color temperature

c. Fixed value of B GAIN, adjust R GAIN and G GAIN, let the color coordinate of the seventh level be 285 and 293. Fixed value of B OFF, adjust R OFF and G OFF, let the color coordinate of second level be 285 and 293 and the brightness be about 3nit-10nit. Adjustment R GAIN, G GAIN, R OFF and G OFF repeatedly until the value of the two levels gray-scale be 285 and 293.

3.3.2 VGA/YPBPR/AV white balance check and correct

a. Input VG-848 signal of VGA: TIMING854(800* 600/60Hz) (PATIERN:CROSS) and auto adjust to full screen, then input PAT948 black/white signal, enter factory menu ADC ADJ, select AUTOTUNE and wait for OK display. Input PAT920(8 gray levels), check if the white balance is normal, if not, set ALL COLOR to 0 and fine adjust according the method of 3.3.1

b. connect VG-848 signal of YPBPR to YPBPR terminal and input TIMING972(1080i/60HZ) color bar of PAT908(include black/white bar), Enter submenu of ADC ADJ, Select AUTOTUNE and wait for OK display. Input PAT920(8 gray levels), check if the white balance is normal, if not, set ALL COLOR to 0 and fine adjust according the method of 3.3.2

c. Input AV signal(PM5518, 8 gray levels) to VIDEO terminal, check if the white balance is normal, if not, set ALL COLOR to 0 and fine adjust according the method of 3.3.2 Note: it can’t set back to 1 once ALL COLOR changes to 0.

4 Software upgrade

When software upgrading please enter factory menu first, enter ISP of OPTION, set ISP to 1 and you can begin to upgrade. After upgrade finished, it needs to set ISP back to 0. If the picture can’t display when upgrading, it needs to web J1 of 01S board. Please disconnect J1 again after upgrading.

5 Performance check

5.1 TV function Enter searching menu → auto search, connect RF-TV terminal with central signal source and check if the picture is normal, if there are channels be skipped. Check TXT and parental control.

5.2 AV/S, YpbPr terminals Input AV/S, YPbPr/YCbCr HD signal, check if it is normal.

5.3 VGA terminal Insert VGA terminal, input VGA format signal of 640X480@60 Hz and check if the display is normal.

5.4 HDMI terminal Insert HDMI terminal, input signal of 640 X 480@60 Hz signal and check if the display is normal.

5.5 check sound channel Check the speaker and headphone of each channel.

5.6 RS232 terminal Insert earphone to COM terminal and check if the long-distance control function is normal.

5.7 other function check Check the turn on/turn off timer, asleep timer, picture/sound mode, OSD, freeze/mute, stereo, ect.

5.8 presetting before ex-factory

Item Setting Item Setting Item Setting

PICTURE MODE STANDARD BALANCE 50 OSD LANGUAGE English

COLOR MODE NORMAL VOLUME 50 OSD HPOSITION 50

NR WEAK SLEEP TIMER OFF OSD VPOSITION 50

ZOOM FULL TTX LANGUAGE WEST OSD HALFTONE 50

SOUND MODE STANDARD BLUE SCREEN OFF OSD DURATION 15

AVC OFF

Working principle analysis of the unit

The RF signal received by antenna will be sent to tuner TUN401, then IF signal will be obtained through high amplifier and mixed frequency, through pre-intermediate amplified by V408, then it will be sent to acoustic surface-wave Z407 to do IF filter and get better IF characteristics, then it will be sent to N404 (TDA4470) to do intermediate amplification, phase-locked loop VCO and synchronous wave detection to get video signal TV-V; after pre-intermediate amplification IF will also be sent to acoustic surface-wave Z406 to do filter at the same time, then it will be sent to N404 to do intermediate amplification and output the second sound intermediate frequency signal (TV-SIF).

The TV-V signal output from TDA4470 together with TV-SIF will be sent to main IC NS4(MST9E88L).

Video signals of AV1/S, VGA, YPbPr and HDMI will be sent to MST9E88L, too.

Video RGB of SCART1 and S-Y, S-C of SCART2 will still be sent to MST9E88L, and the audio signal of them via audio switch N302(HEF4052BT) selection after also sent to MST9E88L.

The main IC NS4(MST9E88L) is a high performance and fully integrated IC, which can realize HDMI processing, video demodulating, video switch selection, A/D and D/A conversion, interlace/de-interlace processing, modes conversion, OSD and low-voltage differential output, ect. And it also has functions of audio selection, processing and MCU.

The video signal via MST9E88L processing, output 4 pairs differential signal and 1 pair clock signal for LCD panel display. TV-V output from TDA4470 via double video amplifying, it will be sent to SCART1 for AV-OUT. AV processed by MST9E88L via double video amplifying will be sent to SCART2 for AV-OUT, too.

Audio signal via MST9E88L processing will be sent to sound amplifier N405 (MP7722DF) amplifying to speaker. The audio also sent to earphone amplifier N406(BH3547F) amplifying to earphone. TV audio signal will be sent to D/A converter NS6(DS4344) through I2S bus converting to analog audio signal TV-L/R, then sent to SCART1 for AV-OUT. At the same time, TV-L/R together with AV-L/R processed by MST9E88L will be sent to audio switch NS8(HEF4052BT), after selecting to SCART2 for AV-OUT.

Block diagram

HDMI

VGA

YPbPr

(DTV)

SCART1-RGB

SCART1-AV

SCART1-L/R

SCART2-L/R

SCART2-Y

EDID

24C02

HDTV SW.

PI5V330

AUDIO SW.

HEF4052

EDID

24C02

SCART2-C

Y/AV1

S-C

TUNER

TV-V

TV-SIF

L/R-VGA

L/R-YPbPr

L/R-AV1/S

AV- L / R

SCART1-V OUT TV-IIS

SCART2-L/R OUT

SCART2-V OUT CVBS

SCART1-L/R OUT

SAW

IF AMP

TDA4470

2*AMP

TV-L/R

POWER MEG.

AT M E G8 L

LCD TV

CONTROLLER

MST9X88LD

D/A

CS4334

HP AMP

BH3547F

AUDIO SW.

HEF4052

DDR

FLASH

EEPROM

HDCP KEY

PANEL

AUDIO AMP.

MP7722

SPEAKER

HEAD

PHONE

IC block diagram

1. MST9E88L

The MST9E88L is a high performance and fully integrated IC for multi-function LCD monitor/TV with resolutions up to SXGA/WXGA. It is configured with an integrated triple-ADC/PLL, an integrated DVI/HDCP/HDMI receiver, a multi-standard TV video and audio decoder, a video de-interlacer, a scaling engine, the MStarACE-3 color engine, an on-screen display controller, an 8-bit MCU and a built-in output panel interface. With external frame buffer, 3-D video decoding and processing are fulfilled for high-quality TV applications. To further reduce system costs, the MST9E88L also integrates intelligent power management control capability for green-mode requirements and spread-spectrum support for EMI management.

2. MP7722DF

The MP7722 is a stereo 20W Class D Audio Amplifier. It is one of MPS’second generation of fully integrated audio amplifiers which dramatically reduces solution size by integrating the following: 180mΩ power MOSFETs Startup / Shutdown pop elimination Short circuit protection Mute / Standby The MP7722 utilizes a single ended output structure capable of delivering 2 x 20W into 4Ωspeakers. MPS Class D Audio Amplifiers exhibit the high fidelity of a Class A/B amplifier at efficiencies greater than 90%. The circuit is based on the MPS’ proprietary variable frequency topology that delivers low distortion, fast response time and operates on a single power supply.

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