Xoceco LC-27U7, LD-32U5 Schematic

LCD TELEVISION

LC-27U7

LC-32U5

Canada

CONTENTS

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

Adjustment instructions …………………………….…….…………………………….…

Working principle analysis……………………………………………………….………….

Block diagram…………………………………..……………….……………….…………

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

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

Troubleshooting………………………………………………………………..……………

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

APPENDIX-A: Main assembly list
APPENCIX-B: Exploded view

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3

6

7

8

12

13

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

servicing please read the following points carefully.

Safety instructions

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

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would be unable to work and no way to get it repaired.

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 instruction

r

1 Alignment equipment

PM5518 (video signal generator)
K-7253 (VGA signal generator)
CA210 (white balancer)

2 Alignment flow-chart

The alignment flow-chart is shown as fig-1

Check DDC, HDCP KEY and CPU

Factory initialization setup

IF channel voltage of TV and AGC voltage adjustment

Support format of VGA pre-set

Adjustment for sub-brightness and white balance of VGA/HDMI (colo

temperature 6500k, 9300k and 12000k)

Adjustment for sub-brightness and white balance of YPbPr/YcbCr channel

Adjustment for sub-brightness and white balance of VIDEO channel

Fig-1 adjustment flow-chart

3 Unit adjustments
Connect digital board, CPU board and analog board according to wiring diagram, connect with
power and observe the display.
Method for entering factory menu: press “SLP”, “DSP”, “MENU” and “DSP” 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” to exit.
Note: the white balance adjustment should be done under “nature” picture mode.

3.1 Initialization
Enter factory menu, select “Factory settings” sub-menu, and adjustment for items of table1.

Preset ex-factory

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Table1 sub-menu adjustment

Items Range Introduce

PW on LOGO ON/OFF Display 5s LOGO of turn on the TV

NO Sig LOGO ON/OFF If display LOGO in no signal

Black Screen BLUE/BLACK If display blue screen and white noise wave in no signal, setting

“BLUE”

MLK 120-159 Adjustment for clock frequency (MHz) of memorizer, setting “145”.

PIP Size Middle/Large Select two component of PIP: “SMALL AND MIDDLE” and “SMALL

AND BIG”, setting “MIDDLE”.

init EEprom Start? Eeprom Initialization (adjustment for EEprom data)

3.2 Adjustment for AFT voltage and AGC voltage of IF channel in TV
Input frequency for 45.75MHz and IF signal for 80dBV of TP1, adjust L107 to value 2.4v of TP2;
when increase 0.10MHz of TP1 input signal, the TP2 value 1.0v at least; but decrease 0.10MHz of
TP1 input signal, the TP2 value 4.0v at least.

3.3 VGA/DVI channel adjustment

3.3.1 Preset VGA channel mode
Input VGA signal (PATTERN: CROSS) of VG-849 or VG-848, select PROG850(640*400/85Hz),
auto adjustment until the screen is filled with picture. Use the same method to do auto adjustment
for the following items:

PROG851(640*480/72 Hz) PROG852(640*480/75 Hz) PROG853(800*600/56 Hz)

PROG854(800*600/60 Hz) PROG855(800*600/72 Hz) PROG856(1024*768/60 Hz)

PROG857(1024*768/70 Hz) PROG858(1280*768/75 Hz) PROG888(800*600/75 Hz)

PROG915(1152*870/75 Hz) PROG915 (1280*1024/60Hz)

3.3.2 Sub-brightness and White balance adjustment VGA/HDMI channel
a. Input VG-849 or VG-848 signal of VGA: PROG852(640* 480/75Hz) and eighth level gray-scale
signal of PATTERN. Use color analyzer CA210 to adjust sub-brightness and white balance.
b. Enter submenu of COLOR TEMP., Select 9300k of color temperature, set auto value of R, G and
B to 50. Enter submenu of white balance, preset value of offset_R, offset_G and offset_B to 125,
and preset value of gain-R, gain-G and gain-B to 100. Adjustment for brightness let the second level
brightness be 3nit at least.
c. Fixed value of offset_B, adjust offset_R and offset_G, let the color coordinate of the second level
be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value of
gain_B, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285 and 293.
Adjustment offset_R, offset_G, offset_B, gain_R, gain_G and gain_B repeatedly until the value of
the two levels gray-scale be 285 and 293.
d. Select 6500k of color temperature, set auto value of R, G and B to 50. Fixed value of B to 50,
adjust R and G, let the color coordinate of the sixth level be 313 and 329. Adjust R and G repeatedly
until the color coordinate value to 313 and 329.
e. Select 12000k of color temperature, set auto value of R, G and B to 50. Fixed value of B to 50,
adjust R and G, let the color coordinate of the sixth level be 270 and 283. Adjust R and G repeatedly
until the color coordinate value to 270 and 283.

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f. Input PROG852(640*480/75Hz) and the eighth level gray-scale of PATTERN signal of VG-849 to
HDMI, repeatedly the b-e course. In the HDMI channel, preset value of offset_R, offset_G and
offset_B to 15, preset value of gain_R, gain_G and gain_B to 25.

3.4 Adjustment for sub-brightness and white balance of YPbPr channel
a. Connect YPbPr signal of VG-849 and VG-848 to YPbPr terminal, input color signal of
PROG973(1080i)PATTERN964. Select AUTOTUNE item, wait for it displays “OK”. NOTE: Don’t
select AUTOTUNE item in other state.
b. Switch YPbPR signal of VG-849 and VG-848 output to the eighth gray-scale signal of
PROG973(1080i)PATTERN964. prset value of offset_R, offset_G and offset_B to 15 and gain-R,
gain-G and gain-B to 25. adjust brightness, let second bright to 3nit at least.
c. Fixed value of offset_B, adjust offset_R and offset_G, let the color coordinate of the second level
be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value of
gain_B to 25, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285
and 293. Adjustment offset_R, offset_G, gain_R and gain_G repeatedly until the value of the two
levels gray-scale be fixed.
d. Input PROG977(720p), PROG978(480p) and PROG968(480i) mode for eighth level gray-scale
signal, let the color coordinate of the second level and the seventh level 285 and 293.

3.5 VIDEO channel adjustment (TV/VIDEO/S-VIDEO)
a. Connect color bar signal of AV (PM5518, NTSC , eight level gray-scale signal) to VIDEO1
terminal, enter factory menu, preset value of offset_R, offset_G and offset_B to 15 and gain-R,
gain-G and gain-B to 25, adjust brightness, let second bright to 3nit at least.
b. Fixed value of offset-B to 15, adjust offset_R and offset_G, let the color coordinate of the second
level be 285 and 293 and its brightness be 4-5nit more or less (it can not 3.5nit at least). Fixed value
of gain_B to 25, adjust gain_R, gain_G and gain_B, let the color coordinate of seventh level be 285
and 293. Adjustment offset_R, offset_G, gain_R and gain_G repeatedly until the value of the two
levels gray-scale be fixed.

4 Performance check

4.1 TV function
Enter searching menu → auto search, connect RF-TV terminal with central signal source and check
if there are channels be skipped

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

4.3 VGA terminal
Insert VGA terminal, input VGA format signal of 640 X 480@60 Hz, check if the display is normal. If
interference exists, press the auto adjusts button on remote control again and check if it is normal.

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

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

4.6 presetting before ex-factory

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Item Setting Item Setting Item Setting

Picture mode NATURE OSD language English CCD OFF

Sound mode NORMAL HALFTONE 50 STEREO ON

N/R WEAK DURATION 30 VGA/HDMI NORMAL

SCREEN FULL MAG.C ON ANTENNA CATV

Working principle analysis

RF signal from the antenna to tuner, via high frequency amplifier and mix frequency to obtain IF
signal, and then via pre-IF amplifier in V104, then it send to processed IF filter of SAW (Z103),
obtain more idea IF speciality, it processed to IF amplifier, phase locked logic VCO and sync
detection of N101 (M52760E) in the TV board to obtain VIDEO; IF via pre IF amplifier to send to
processed filter of SAW (Z102), again send to processed IF amplifier of N101, decode second SIF.
From M52760E output VIDEO, AV1 and AV2/S signal all send to video decoder N601
(TVP5147PFP), via video select, clamping, A/D transfer, comb filter and color decode, one way
output AV OUT, another way output 8bit for CIR656 format signal and CLK signal, send to
N101(MST6151) of CPU board, Also YPbPr, VGA and HDMI send to N101. N101(MST6151) is
many function big dimension integrate circuit, it processed HDMI, A/D to D/A switch, interlaced and
non-interlaced processing, model switch and low voltage difference output functions and so on, it
send to four ways difference signal and one way clock signal to LCD display.
From HDMI input to MST6151contain sound signal, via processed MST6151, send to processed
D/A switch for NA01(CS4340), output L/R of HDMI.
L/R of HDMI from CS4340 output, L/R of YPbPr and VGA/DVI signal via sound switch
NA02(HEF4052) to select, then send to sound processing N801(MSP3425G); L/R signal for AV1
and AV2/S input send to N801 via selected switch N701(HEF4052),and SIF of TV output from
M52760E send to N801 too. In MSP3425G, the demodulated L/R of SIF and the input L/R from
other two ways, via selected switch and processing sound, then output signal, one way sound
output for AV OUT, other way send to N401(TPA3008D2) of sound amplifier, via amplify for sound
signal to speaker and earphone.
The unit working is controlled N801(MTV412) of CPU, connect tuner, TVP5147 and MSP3425G to
IIC bus; connect MST6151 to parallel BUS.

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Block diagram

N

N

N

N

N

N

N

N

N

N

N

N

N

HDMI-A AV-A OUT

YPbPr-A

VGA/DVI-A L/R

L/R

AV 1 - A

AV 2 / S - A

L/R

SIF

RF

V IIC

AV-V OUT

VIDEO1 CCIR656

Y/VIDEO2 8bit

C

YPbPr

VGA

HDMI/DVI

L/R

BUS

L/R

TUNER

HDMI-A

AUDIO

SW

A02

HEF4052

AUDIO

SW

701

HEF4052

IF

EEPROM

802

EEPROM

803

SAW

Z102

SAW

Z103

VIDEO

DECORDER

601

TVP5147PFP

DAC

A01

CS4340

IF AMP

M52760E

MCU

801

MTV412

AUDIO

PROCESSOR

801

MSP3425G

101(TV board)

SCALER

A/D D/A

DEINTERLACER

LVDS

HDMI

MST6151DA

SDRAM

101(CPU board)

SDRAM

201

202

AUDIO AMP

401

TPA3008D2

SPEAKER

HEADPHONE

PANEL

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IC block diagram

TVP5147

CVBS/

C/Pb

CVBS/

Y

CVBS/

C/Pr

CVBS/Y

VI_1_A
VI_1_B

VI_1_C

VI_2_A

VI_2_B

VI_2_C

VI_3_A

VI_3_B

VI_3_C

VI_4_A

Analog

Front End

Clamping

AGC

2 11-Bit

ADC

Sampling
Clock

Copy

Protect ion

Detector

M

U

X

Timing Processor

With Sync Detector

CVBS/Y

CVBS/Y

C/CbCr

VBI

Data

Processor

Composite and S-Video Processor

Y/C

Separation

5-line

Adaptive

Comb

Y

C

Luma

Processi ng

Chroma

Processi ng

YCbCr

Interface

Y[9:0]

Output

Formatter

C[9:0]

GPIO

Host

XTAL1

XTAL2

PWDN

AVI D

RESETB

DATA CL K

80: AV OUT
2: TV-V input
7: AV1-V input
9: AV2-V/S-Y input
18: S-C input
29: SDA
28: SCL
40: CLK output
43-47, 50-52: CCIR656 format signal output
4, 5, 20, and 21: 3.3V-A power supply
38, 48, 61: 3.3V-D power supply
11, 25, 76: 1.8V-A power supply
31, 41, 55, and 67: 1.8V-B power supply

FID

VS/VBLK

GLCO

HS/CS

SCL

SDA

8

M52760

2: AFT
3: AGC
4, 5: picture If input
7: sound IF input
13: SIF output
10: mono sound output
18: TV- VIDEO output
14, 17: +5V-1 power supply

MSP3425G

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MST6151

207, 208: HDMI-R input
2, 3: HDMI-G input
5, 6: HDMI-B input
8, 9: HDMI-CLK input
14: HDMI-SDA
15: HDMI-SCL
20, 21: VGA-B input
22: VGA-G input
23, 24: VGA-G input
25, 26: VGA-R input
18: VGA H-sync input
19: VGA V-sync input
27, 28: PB input
29, 30: Y input
31: HDMI-G input
32, 33: PR input
54-61: CCIR656 format signal input
53: CLK input
164-171, 174: 4 difference signal output
160, 161: 1 clock signal output
188-191: HDMI sound output
200: PWW (brightness control switch) output
72-75: BUS (parallel communication signal)
49, 131, 195: 1.8V power supply
4,17,12,109,204,66,102: 3.3V power supply

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