Xoceco LC-37HU19 Schematic

LCD TELEVISION

LC-37HU19

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

1

3

6

7

8

14

15

21

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

1

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
damage.

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.

2

Alignment instructions

1. Test equipment

PM5518 (video signal generator)
VG-849 (VGA and HDMI 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

Factory initialization setup

IF channel AFT voltage of TV and AGC voltage

VGA, YPbPr ADC correction

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.
Method for software upgrading: enter factory menu and select “OPTION”, set ISP to 1 or insert
jump wire J1, then you can upgrade on line. After upgrade, set ISP back to 0 or pull out jump wire
J1.

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

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

Performance check

Preset ex-factory

0: HOTEL OPTION of factory menu is not optional

0: no LOGO display

3

ADC PRESCALE 00A Software auto preset according the power consumption

SIF PRESCALE 000 Software auto preset according the power consumption

BACK LIGHT 13 Software auto preset according the 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

NO STANDY 0 0 01: turn on 00: memory function of turn on 10: standby

INIT VOLUME 0-100 Volume when turn on

INIT CHANNEL 1-200 Channel when turn on

INIT SRC Program source Input Source when 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 AFT adjustment
Enter factory menu, set IF VCO to 1, or press ”INPUT”, “2”, “5”, “8”, “1” to enter VCO

adjustment mode, disconnect J2, adjust LZ100 to value 2.5V of TP5(B face), then wed J2.

3.2.2 IF AGC adjustment

Input 184.25MHz RF signal of 60DBuv from RF terminal for china, and 175.25MHz for
America, adjust RZ133 to value 2V of TP1(B face) and there should be no obvious snowy picture.
Increase the signal to 90DBVuv and it should be display normally and no obvious noise.

3.3 White balance adjustment

3.3.1 HDMI white balance correct

a. Input VG-848 signal to HDMI: TIMING854(800*600/60Hz) 8 level gray scale of PAT920,

adjust the balance with CA210.

b. Enter COLOR TEMP sub menu and select color temperature of standard(9300K)

c. Fixed B OFF, adjust R OFF, G OFF to let the color coordinate of the second level be
283,297(CPT panel) and the brightness be 3nit ~10nit or so; Fixed B GAIN, adjust R GAIN, G GAIN
to let the color coordinate of the seventh level be 283,297(CPT panel). Repeat adjust R OFF, G OFF,
R GAIN and G GAIN, until the two color coordinate of the level gray scale be 283,297(CPT panel).

3.3.2 VGA/YPbPr white balance check and correct

a. Connect VG-848 signal of VGA to VGA terminal and input TIMING854(800*600/60HZ)
(PATTERN:CROSS), and auto adjust to full screen then input PAT948 black/white signal, 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

b. connect VG-848 signal of YPbPr to YPbPr terminal and input TIMING972(1080I/60Hz)
PAT908 color bar(include back/white bar), enter submenu of ADC ADJ, select AUTOTUNE and wait
for OK displaly. 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 PAL for China and NTSC for America) to VIDEO 1
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

4 Performance check

4.1 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 CCD and V-CHIP function for
America.

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

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

4.4 HDMI terminal
Insert HDMI terminal, input 640X480@60Hz signal, check if the display is normal. Check HDCP
function.

4.5 check sound channel
Check the speaker and earphone of each channel.

4.6 RS232 terminal
Put the earphone line into COM terminal, check the long-distance control function with special test
software.

4.7 other function check
Check the turn on/turn off timer, asleep timer, picture/sound mode, OSD, freeze/mute,
stereo/SAP(for America), ect.

4.6 presetting before ex-factory

Item Setting Item Setting Item Setting

PICTURE MODE NAUTRAL OSD English/Chinese

COLOR MODE DK HALFTONE 50

SOUND MODE NEWS DURATION 15 VGA/HDMI STANDARD

NR WEAK ANTENNA CATV

ZOOM FULL Turn off channel TV

5

Working principle analysis of the unit

The RF signal received by antenna will be sent to tuner TUN1, then IF signal will be obtained
through high amplifier and mixed frequency, through pre-intermediate amplified by VZ100, then it
will be sent to acoustic surface-wave ZZ101 to do IF filter and get better IF characteristics, then it
will be sent to NZ100 (R2S1040) to do intermediate amplification, phase-locked loop VCO and
synchronous wave detection to get video signal TV-CVBS; after pre-intermediate amplification IF
will also be sent to acoustic surface-wave ZZ100 to do filter at the same time, then it will be sent to
NZ100 to do intermediate amplification and output the second sound intermediate frequency signal
(TV-SIF).

The TV-CVBS signal output from R2S1040 together with TV-SIF will be sent to main IC NS4
(MST9U88L). Video signal of AV1, AV2, S-VIDEO, YPbPr1 and YPbPr2 will also be sent to
MST9U88L; while the audio signal of them via audio switch NW200(HEF4052BT) selection to
MST9U88L (AV1 and S-VIDEO share one audio port). Video and audio signal of VGA, HDMI will be
sent to MST9U88L, too.

The main IC NS4(MST9U88L) is a high performance and fully integrated IC, which can realize
HDMI interface 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 MST9U88L processing, output 4 pairs differential signal and 1 pair clock
signal for LCD panel display. Video signal of AV1, AV2, S-VIDEO and TV via initial selection and
processing, output video signal of AV-OUT, after double video amplifying, it will be sent to AV-OUT.

Audio signal via MST9U88L processing, output two ways; one way will be sent to sound
amplifier NA6(MP7722DF) amplifying, then sent to speaker. At the same time, it also sent to
earphone sound amplifier N350(BH3547F), after amplifying then sent to earphone. Another way will
be sent to D/A converter NS6(CS4344) through I2S bus, convert to analog sound signal L/R output
through AV-OUT.

6

Block diagram

TUNER

Pre-IF

IF

HDMI

PC

HD1/HD2

AV1/AV2/

TV-Video

L/R-DVI/PC

EDID

EDID

EEPROM

HDCP
KEY

Serial flash

DDR

MST9X88L

Power
controlMeg8

I/O port

P

A

N

E

L

L/R-HD1

L/R-HD2

L/R-AV1

L/RAV2

TV-SIF

L/R-MUX

4052

I2S

DAC

CS4344

L/R-OUT VIDEO-OUT
AV OUT

2 multiple
video amplify

7

Earphone amplifier

Earphone

D class amplifier
MPS7722

Speaker

IC block diagram

1. MST9U88L

The MST9U88L is a high performance and fully integrated IC for multi-function LDC 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 application. To further reduce system costs, the MST9U88L also
integrates intelligent power management control capability for green-mode requirements and
spread-spectrum support for EMI management.

8