Xoceco LC-37T18, LC-37T26 Schematic

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LCD TELEVISION

LC-37T26/18

CONTENTS

Safety precautions………………………………………………………………………..…

Alignment instructions …………………………….…….…………………………….…

Working principle analysis of the unit……………………………….………….………….

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

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

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

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

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

APPENDIX: 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.

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

Digital multimeter, signal generator (54200) PC set (FLASH writing programs and W24CXX.EXE have to be installed first,) VG849 (HDMI signal generator) CA210 (White balancer), DVD player(with HDMI output), monitor

2. The alignment flow chart (see below Fig.1)

Write N105, N403, N607, N70, N606

To produce main board, TV board and other board

Check the TV board

Check accessories and then packing

Check the MAIN board

Check the buttons board and IR receive board

Combined test for general assembly

Aging

ADC correction and white balance adjustment

Input the center signal source, check if various functions of TV (search channel, system identify and analog control etc.), earphone output, speake output and the picture and sound of AV-out is normal. (check stereo/SAP, CCD and VCHIP fo American unit)

Input VGA signal source, check is the display is

ormal in PC state and various function (analog control) H-V center etc. The AV-out output soun is originally signal

Input HDMI and DVI signal source, check if the HDCP KEY is normal. The AV-out outpu

sound is originally signal

Input YPbPr/YCbCr 1/2 signal source; check i the picture and sound analog control is normal i the COMPONENT state. The AV-out output soun is originally signal

Input AV1/S/AV2 signal source, check if the various terminal functions (system identify an analog control etc.) and the picture and sound o AV-out is normal. (S-terminal shares the same audio channel with AV1, and it can be auto identified)

Fig.1 Flow process of alignment

3. Alignment instructions

3.1 flash write programs Flash write N606, N607, N105, N403, N701 Flash write W24CXX.EXE into N102 with self-made flash write tool on the line.

Note: N606 may upgrade from the socket X1

N701 may upgrade from the serial wire N102, N403 may upgrade from HDMI and VGA interface respectively N105 can not upgrade on the line, so ensure HDCP KEY is right

3.2 the main board adjustment a. Connect the X602 of main board to the infrared receive board, the supply power plug to X1, then

the indicator of the infrared receive board is red light.

b. Press the POWER button; the indicator change to blue light, the LED1 of main board is flicker of

slow. c. Write EDID program to N102 d. Check if various channels are normal.

3.3 The TV board adjustment a. Connect the high frequency board to main board, and connect the X501 and X502 to the supply

power. b. Press the POWER button, the indicator change to blue light. c. Check if the picture and sound of TV/AV1/AV2/S/YPBPR1/YPBPR2 and sound of HDMI/VGA

channels are normal. Check the STEREO and SAP. Check AV-OUT function: the picture and

sound of AV-OUT should be the picture and sound of the current channel at TV/AV1/S/AV2, at

other signal source, the sound of AV-OUT should be the sound of the current channel, but the

picture don’t need to check.

3.4 the unit adjustment After install the unit, check it is normal working.

3.5 Aging a. Select the TV channel, the screen is noise wave of no signal TV b. Aging an hour.

3.6 ADC correction and white balance adjustment (use white balancer CA210 and signal generator VG849) Enter the factory menu method: press “1”→ “9” → “7” → “9” button in the window menu state a. Enter VGA channel,input 16 level gray signal of 1024*768@60Hz b. Enter PICTURE menu, set “Color Temp” to “Middle” c. Enter the factory menu, press AUTO ADC CALIBRATION and operate according the prompt. d. Input 8 level gray signal of 1024*768@60Hz

brightness until the brightness value of CA210 is 180±10nit. Enter “color temperature” item, fix

“red color temperature”, adjust “blue color temperature” and “green color temperature” so that

x=0.284±0.02, y=0.299±0.02. e. Enter YPBPR channel, input 720P SMPTE COLOR BAR signal(TIMING:976, PATTERN:984) f. Enter factory menu, press AUTO ADC CALIBRATION and operate according the prompt. g. Input 720P 8 level gray signal and test the fourth level with CA210, adjust the brightness until

the brightness value of CA210 is 180±10nit. Enter “color temperature” item, fix “red color

temperature”, adjust “blue color temperature” and “green color temperature” so that

x=0.284±0.02, y=0.299±0.02.

and test the fourth level with CA210, adjust the

(TIMING:889, PATTERN:921).

4 Performance check

4.1 TV terminal Input the center signal source to RF terminal, enter searching menu → auto search, check if the leak channel, half-auto search channel, fine tune, earphone and speaker are normal. Check stereo/SAP/CCD/ Parent Control for America unit. Check the AV OUT.

4.2 AV1/S/AV2 input terminals Input AV1/S/AV2 signal source, check the picture, sound and the output of AV-OUT. Check if it can auto-jump to S-terminal when insert S-terminal at AV1 state.

4.3 VGA terminal Input the VGA signal (K7253 signal generator), separate input VGA format signal of table 1, check the picture and sound

Table1 PC display format signal

No. Resolution H-frequency(kHz) V-frequency(Hz)

1 720 x 400 31.47 70.08 25.17 DOS

2 640 x 480 31.50 60.00 25.18 DOS

3 640 x 480 37.90 72.00 31.50 Mac.(SOG)

4 640 x 480 37.50 75.00 31.50 VESA

5 640 x 480 43.30 85.00 36.00 VESA

6 800 x 600 35.16 56.25 36.00 VESA

7 800 x 600 37.90 60.00 40.00 VESA

8 800 x 600 46.90 75.00 49.50 VESA

9 800 x 600 48.08 72.19 50.00 VESA

10 832 x 624 49.00 74.00 57.27 Mac.(H+V)

11 1024 x 768 48.40 60.00 65.00 VESA

12 1024 x 768 56.50 70.00 75.00 VESA

13 1024 x 768 60.00 75.00 78.75 VESA

14 1280 x 1024 64.00 60 108.00 SXGA

15 1280 x 1024 80.00 75 135.00 SXGA

pixel clock pulse

frequency(MHz)

4.4 YPbPr terminal Input the YPbPr signal source (K7253 signal generator), separate input format signal of table 2, and check the picture and sound. If the image is slight disturb, press auto correction button of the remote controller and check if it is normal.

Table 2 Component format signal

No. H-frequency(kHz) V-frequency(Hz) signal

1 15.735 60 SDTV 480i

2 15.625 50 SDTV 576i

3 31.47 60 SDTV 483p

4 45.00 60 HDTV 720p

5 33.75 60 HDTV 1080i

6 28.13 50 HDTV 1080i

remark

4.5 HDMI terminal Input the DHMI signal source (VG849 signal generator), separate input format signal of table 3, check the picture and sound.

Table 3 HDMI format signal

No. H-frequency(kHz) V-frequency(Hz) signal

1 15.735 60 SDTV 480i

2 15.625 50 SDTV 576i

3 31.47 60 SDTV 483p

4 45.00 60 HDTV 720p

5 33.75 60 HDTV 1080i

6 28.13 50 HDTV 1080i

HDMI format signal of audio

channel 2

sampling rate support 32Kbit/s 44.1Kbit/s 48Kbit/s

bit wide support 16bit,20bit,24bit

4.6 Ex-factory preset Enter the factory menu in the status of TV, then perform the ex-factory preset.

4.7 Packing

Check the accessories and then packing.

Working principle analysis of the unit

The unit has two MCU, the main MCU is PW218 (N601): it is used to control all the chips’ working status on the main board (including image processing, channel switch, sound processing, image display etc.), sub CPU, OSD, searching channels, image effect adjustment, buttons control, infrared remote control etc.; the sub CPU is ATMEGA8L (N606): it is used to control power supply, including standby and turning on the unit by using remote control etc.. The two MCU correlates with each other through pin 14 INT (interruption) of ATMEGA8L, pin 28 and 29 SDA, SCL. This unit adopts the integrative tuner (contains HF and IF amplifier circuits), antenna reception signal will be sent to tuner, the tuner is controlled by SDA, SCL of the MCU PW218(N601),selects appropriate channel to system switch, via HF and IF amplifier decoder, outputs video and sound signal. Video signal of tuner will be sent to decoder PW2300 (N201), while Audio signal of the tuner will then be sent to AV switch box M52797 (N400), the audio signal of AV1, AV2 and HD2 of the main board will also be sent to M52797 (N400) at the same time. The selected audio signal after switching will be sent to MSP3425, and then switching selection will be done towards the above audio signal together with the audio signal of VGA, HDMI and HD1. The two chips are controlled by PW218 (N601), after the above process the finally selected way will be sent to X300 earphone socket after under the control of volume, treble and bass, the earphone socket has the switching function, when earphone is plugged, sound will be sent to earphone amplifier LM4808, then sent back to earphone socket after power amplification. If earphone is unplugged, sound will be sent to sound amplifier TPA3008 to do amplification and then sent to speaker.

Image parts: Video signal of TUNER will be sent to AV switch M52797 (N400), Video signal of AV1 and AV2 will also be sent to M52797 (N400) at the same time, two groups of video output will be obtained after switching, one group of video output together with its audio output will be sent to AV_OUT terminal to treat as AV OUT. The other group of video output together with other video signals such as S-VIDEO, YPbPr1, YPbPr2 and VGA will be sent to PW2300 to do video decoding or AD transformation, then output 24bit digital RGB signal and some corresponding synchronous signals. Items such as 3D comb filter, channel switching, 5 lines Y/C separation and color decoding etc. are primarily done by PW2300. 24bit digital RGB signal and some corresponding synchronous signals outputted by PW2300 will then be sent to PW218 (N601). HDMI signal will also be sent to AD9398 (N101) to do decoding and output 24bit digital RGB signal as well as some corresponding synchronous signal, which will be sent to PW218 (N601). PW218 is a new generation chip of Pixelworks, which has ability to deal with images, 24bit digital RGB signal and some corresponding synchronous signals outputted by AD9398 and PW2300 will be sent to this chip to deal with images. The chip has functions such as converting from interleaved into line-by-line and image enhancement etc.. PW218 has SCALER function which can do format conversion towards different input formats so as to meet the format needs of the screen and finally output 24bit RGB signal. The interface standard of PDP screen is generally LVDS (low voltage differential signal), so PW218 send LVDS to drive the screen. PW218 is also the main CPU, its programs are stored in periphery device flash N701, and software upgrade through RS-232 interface is virtually upgrading the stored programs through PW218 towards N701. Chief functions: High definition 1080P LCD 16:9 wide screen; Support several kinds of HDTV wide voltage range, low standby power consumption (less than 1W); One group of D-SUB, S-VSH (Y/C), RS232, AVOUT, HEADPHONE, HDMI, two groups of YPbPr/YCbCr, AV.

Block diagram

E2PROM

KEY

YPbPr2 Audio

HDMI

RS232

S Video

YPbPr2

YPbPr1

AV1

AV2

AV Out

RF Video

Tuner

RF Audio

MAX3232C

STERO/SAP decoder

Audio and video

M52797SP

switch

N400

or AD9398

AD9880

memory

CS4334

PW2300

AV Audio Out

MSP3425

YPbPr1 Audio

PC Audio HDMI Audio

DDR 256M

SDRAM

24LC32

G port

I2C2

EEPROM

TPA3008D2

V port

LM4808

PW218C

Flash

with switch

Earphone

socket

MEGAL8

LCD Panel

I2C1

KEY

IC block diagram

1. AD9880 and AD9398

AD9880 have HDMI digital and analog terminal of working frequency 165Hz, it support 1080P (non-interlaced scanning) and UXGA (1600 x 1200/60Hz) video format, also it support eight audio channel of 192KHz. AD9398 without analog terminal. Internal Block Diagram

PIN configuration

AD9880 (AD9398) PINS FUNCTIONS

Pin Name Function Pin Name Function

2-9 GGE(0-7) Converter output 44 RXC+ DVI input

12-19 GBE(0-7) Converter output 49 DDC_CLK HDCP Slave Serial Port

Data Clock

92-99 GRE(0-7) Converter output 50 DDC_DATA HDCP Slave Serial Port

Data I/O

20, 21 MCLK Control clock output 51 MCL HDCP Master Serial Port

Data Clock

22 I2S_SCK Audio serial clock output 52 MDA HDCP Master Serial Port

Data I/O

23 I2S_WS Bus clock data output 82 SCL-1 Serial Port Data Clock

27 I2S_SD Bus audio data output 83 SDA_1 Serial Port Data I/O

34 RX0- DVI input 84 G_FIEL0 Odd/Even Field Output

35 RX0+ DVI input 85 G_VS VSYNC Output Clock

37 RX1- DVI input 86 G_VHS Sync on Green Slicer

Output

38 RX1+ DVI input 87 G_HS HSYNC Output Clock

40 RX2- DVI input 88 G_DE Data Enable

41 RX2+ DVI input 89 G_CLK Data Output Clock

43 RXC- DVI input

2. PW2300

PW2300 is front processing signal of integration highly performance, multi-system, 3D video decoder and three highly velocity AD converter chip. It supports HDTV, NTSC, PAL and SECAM. Its analog port support 1080P(150MHz). Internal Block Diagram

PW2300 PINS FUNCTION

Pin Name Function Pin Name Function

A4 XIN Resonator input P1 R_2 AV2 red input

A5 XOUT Resonator input P2 B_2 AV2 greed input

B2 SDA I2C bus data P3 SOG_2 AV2 greed sync input

B3 SCL I2Cbus clock P4 G_2 AV2 blue input

C5 R1 CVBS_1 TV composite video signal input

D5 R2 Y_1 S-VHS brightness signal input

K2 VGA-R1 VGA(red) R3 CVBS_SOG1 TV composite video signal greed sync

input

K1 VGA-G1 VGA(greed) R4 C_1 S-VHS chrominance signal input

L1 VGA-SOG1 VGA(greed sync signal) AB S_DECT

M1 VGA-B1 VGA(blue) B9 GVBI Vertical blanking blank

T1 VGA_H VGA(H-sync signal) E15 GFIELD

T3 VGA_V VGA(V-sync signal) E16 G_VS V-SYNC output

N1 R_1 AV1 red input F14 G_HS H-SYNC output

N1 G_1 AV1 greed input F15 G_AHS H-SYNC of non-processing

N3 SOG_1 AV1 greed sync input F16 G_DE

N4 B_1 AV1 blue input G15 G_DLK Clock output

GBO(2-9) Blue odd pixel data output GBE(0-7) blue even pixel data output

GGO(2-9) greed odd pixel data output GGE(0-7) greed even pixel data output

GRO(2-9) red odd pixel data output GRE(0-7) red even pixel data output

3. PW218

PWE218 is highly quality SOC picture processing chip, it contains Scaling and Deinterlacing functions. Internal Block Diagram

4. TPA3008

TPA3008 is double channel 10W stereo D class audio amplifier. Internal Block Diagram

PINS FUNCTION

Pin Name Function Pin Name Function

1 SHUTDOWN Shut down control signal 17 LOUTN Negative audio output for left channel

3 RINP Positive audio input for right channel 20 LOUTP Positive audio output for left channel

4 V2P5 2.5V Reference for analog cells. 27 ROSC I/O current setting resistor for ramp

generator.

5 LINP Positive audio input for left channel 41 ROUTP Positive audio output for right channel

11 FAULT Volume control 44 ROUTN Negative audio output for right channel

5. M52797D

The M52797 is AV switch semiconductor integrated circuit with I2C bus control. Internal Block Diagram

Pin description

Pin Name Description Pin Name Description

3 HD2_L Audio input 5 HD2_R Audio input

6 AV1_L Audio input 8 AV1_R Audio input

9 AV2_L Audio input 11 AV2_R Audio input

27 TV_L Audio input 25 TV_R Audio input

24 Left audio channel output 22 Right audio channel output

6.CM2006

It includes ESD protection, level-shifting, buffering and sync impedance matching Internal Block Diagram

Pin description

Pin Name Description Pin Name Description

1 VCC 3.3V 11 DDC_IN2 DDC _input2

3, 4, 5 VIDEO_1_2_3 Video input 12 DDC_OUT2 DDC output

6 GND GND 13 SYNC_IN1 Sync input1

7 Vcc-DDC 5V DDC 14 SYNC_OUT1 Sync output1

8 BYP Bypass capacitance 15 SYNC_IN2 Sync intput2

9 DDC_OUT1 DDC output 16 SYNC_OUT2 Sync output2

10 DDC_IN1 DDC _output1

7. MSP3425

The MSP 34X5G family of single-chip Multistandard Sound Processors covers the sound processing of all analog TV standards worldwide, as well as the NICAM digital sound standards. The full TV sound processing, starting with analog sound IF signal-in, down to processed analog AF-out, is performed in a single chip. Figure below shows a simplified functional block diagram of the MSP 34X5G.

Pin description

Pin Description Pin Description

2 SIF IN 29 AVOUT_R

12 I2C_CL 30 AV OUT_L

13 I2C_DA 40 SC1_IN_L

25 OUT_R 41 SC1_IN_R

26 OUT_L 42 VEEFTOP

43 MONO_IN

X608

X601

X101

X401

X402

XA01

X607

X605

X606

X601

X300

X700

X502

X501

X604

CN2

CN1

Wiring diagram

782-LYT25-0100

TUNER

AV OUT

YPBPR audio IN

AV I N

S-VIDEO

2 YPBPR

X500 X604 X602 X603

X3（12） X4 X6 X5

VGA AUDIO IN

VGA

HDMI

RS-232C

782-LYT25-5500

KEY BOARD

X603

HEADPHONE

CN1

Power module

X602

CN2 CN3

CN4 CN5

LCD panel

CNF1 J1

AC220

Remote receiver

Speaker

Trouble shooting

1. Fault clearance

Before servicing please check to find the possible causes of the troubles according to the table

below.

1.1 Antenna (signal):

Picture is out of focus or jumping

Fringe in picture  Check if the antenna is correctly oriented.

Picture is interfered by stripe shaped

bright spots

There appear streaks or light color

on the screen

1.2 TV set:

Symptoms Possible cause

Unable to switch the power on  Check to see if the power plug has been inserted properly

No picture and sound  Check to see if the power supply of liquid crystal TV has

Deterioration of color phase or color

tone

Screen position or size is not proper  Check is the screen position and size is correctly set up.

Picture is twisted and deformed  Check to see if the picture-frame ratio is properly set up.

Picture color changed or colorless  Check the “Component” or “RGB” settings of the liquid

 Bad status in signal receiving

 Poor signal

 Check if there are failures with the electrical connector or

the antenna.

 Check if the antenna is properly connected.

 Maybe there is electric wave reflected from hilltop or

building.

 Possibly due to interference from automobile, train, high

voltage transmission line, neon lamp etc.

 Maybe there is interference between antenna and power

supply line. Please try to separate them in a longer

distance.

 Maybe the shielded-layer of signal wire is not connected

properly to the connector.

 Check if interfered by other equipment and if interfered

possibly by the equipment like transmitting antenna,

non-professional radio station and cellular phone.

into the socket.

been switched on. (As can be indicated by the red LED at

the front of the TV set)

 See if it’s receiving the signal that is transmitted from other

source than the station

 Check if it’s connected to the wrong terminal or if the input

mode is correct.

 Check if the signal cable connection between video

frequency source and the liquid crystal TV set is correct.

 Check if all the picture setups have been corrected.

crystal TV set and make proper adjustment according to the

signal types.

Picture too bright and there is

distortion in the brightest area

Picture is whitish or too bright in the

darkest area of the picture

No picture or signal produced from

the displayer if “XXX in search”

appears.

There appears an indication -

“outside the receivable scope)

Remote control cannot work

properly

No picture and sound, but only

hash.

Blur picture  Check if the antenna cable is correctly connected.

No sound  Check if the “mute” audio frequency setting is selected.

When playing VHS picture search

tape, there are lines at the top or

bottom of the picture.

 Check if the contrast setting is too high.

 Possibly the output quality of DVD broadcaster is set too

high.

 It maybe also due to improper terminal connection of the

video frequency signal in a certain position of the system.

 Check if the setting for the brightness is too high

 Possibly the brightness grade of DVD player (broadcaster)

is set too high.

 Check if the cable is disconnected.

 Check if it’s connected to the proper terminal or if the input

mode is correct.

 Check if the TV set can receive input signal. The signal is

not correctly identified and VGA format is beyond the

specified scope.

 Check if the batteries are installed in the reverse order.

 Check if the battery is effective.

 Check the distance or angle from the monitor.

 Check if there is any obstruct between the remote control

and the TV set.

 Check if the remote control signal- receiving window is

exposed to strong fluorescence.

 Check if the antenna cable is correctly connected, or if it

has received the video signal correctly.

 Of if it has received the right video signal.

 Check if the sound volume is set to minimum.

 Make sure the earphone is not connected.

 Check if the cable connection is loose.

 When being played or in pause VHS picture search tape

sometimes can’t provide stable picture, which may lead to

incorrect display of the liquid crystal TV, In this case please

press “auto” key on the remote control so as to enable the

liquid crystal TV set to recheck the signal and then to

display correct picture signal

2. Identification criteria for the bright spot and dark spot of the LCD screen

Category Criteria

One single

spot

Bright

spot

Dark

spots

Total defected point ≤8 ≤7 ≤5 ≤4 /

Two

neighboring

spots

Tot a l N o . ≤5 ≤2 ≤5 ≤2 ≤3

One single

spot

Two

neighboring

spots

Tot a l N o . ≤6 ≤7 ≤5 ≤4 ≤10

15" 20" 22" 30" 40" 15" 20" 22" 30" 40"

≤5 ≤2 ≤5 ≤2 ≤3

≤2 ≤1 ≤2 ≤1 ≤1

≤6 ≤7 ≤5 ≤4 ≤10

≤2 ≤2 ≤2 ≤1 ≤5

Notes:

1. Definition of defected point (bright spot, dark spot): It is identified as a defected point if its area exceeds 1/2 of a single picture element (R, G, B).

2. Definition of bright spot: It is identified as a bright spot if it is bright in the state of dark field and its bright size remains unchanged

3. Definition of dark spot: It is identified as a dark spot if it is dark in the state of white field and its dark size remains unchanged

4. Definition of two neighboring points: Defects of a group of picture elements (RB, RG, GB).

Quantity allowed Distance between two spots

≥15mm

≥10mm ≥5mm

3. Troubleshooting guide

3.1 No raster, no picture and no sound

Short circuit the pin 1 (STANDBY)

of X604 to 5V, then check the

supply power.

Check the suppl

ower +3.3V

bnormal

bnormal Normal

Normal

606

abnormal

Pull out X604 an

check power

Normal

bnormal

Check the

supply powe

of N606 an

crystal.

Normal

Short circuit i

a power line

Power board

Check the power o

201, N601, N204

and N701, crystal an

us.

Note: Power supply for PDP is provided with over current and over voltage protection functions.

If there is over current or over voltage, this protection will function and no output.

Check if the indicator is light

Yes

Check N501 and

601

roblem

Cut off connection between the

ower board and signal processing

board, check the 5V-STBY

Cut off the the power

oard and video board

to main board, chec

Check 5V-STBY

bnormal Normal

Power board

roblem

2.With sound but no picture:

Check if no image for all

other channels

Yes

Ye s

With sound but no picture

Display LOGO?

Check signal

wave of X3, X4

Check the N201

and peripheral

circuit

Refer to (4)

checking procedure

Check input signal of N601

and power supply

601

damaged

ormal

Abnormal

ormal Abnormal

Check N201 and the

circuit of output part

Unfix X3 and X4, turn on the unit and

check if display the white screen

ormal

Abnormal

Check the suppl

ower (+120) o

backlight board

Abnormal

The supply powe

oard damaged

3.With picture but no sound.

No N

Sound power amp. or other peripheral circui

have problem. Check power supply, i

SHUTDOWN pin control is normal and i

output short circuite or other problems tha

cause protection to work.

Check if input signal in pin 3,5 of

sound power amplification

Ye s

With picture but no sound

Measure if the sound input of the

resent channel corresponding to

400 is normal

If there is output from X700 o

sound power amplification board

Ye s

Sound box damaged

o Ye s

MSP3425 or other peripheral

circuit have problem

Check different levels o

circuit following input audio

signal channel

4. AV no picture

Check if pin 7(AV1) and pin10 (AV2)

of N400 has signal input

Check if the pin1 of X4 has signal output

o Yes

The path from N400 to

X4 have problem

PW2300 or other peripheral circuit have problem

Ye s

There is problem from Av

socket to N102 channel

Measure the resistor row of N201 an

check if the output of PW2300 is normal

Ye s

PW218 or other peripheral circuit have problem

5. Troubleshooting guide of power supply board

NNN

N N N

a. No power supply

o power supply

Does AC voltage at C560

Check if X501 FU501 is

roperly inserted?

Does DC voltage at C529

(250~370V)

Check D502, R530, D509

Check if the 15V DC o

501 (pin13)

Check N501 or peripheral

circuit

b. No DC voltage output

Check supplementar

ower supply

o DC voltage output

Check if DC voltage of C535 is

3.3V(5V)

Check DC voltage of V505 B

(>1.5V)

Check if DC voltage of C547 is

24V

Check N502 or peripheral

circuit

Check main board

Check D515 or T501

Check FU503

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power board

power filter

board

APPENDIX: Exploded view(LC-37X18)

PART LIST OF EXPLODED VIEW (LC-37X18)

No. PART NO. DESCRIPTIONRE 1 808-20358-212 ACTIVE panel 2 Front cover 3 870-10289-00 power supply bracket 4 360-30042-00 Power switch 5 700-60255-100 LED column 6 870-30216-00 LED columnbracket 7 700-60255-100 LED column 8 9 Screen 10 870-1A235-00 Board connecting bracket 11 870-1A238-00 Board connecting bar 12 870-1A231-00 Connecting bracket of screen 13 870-10249-00 Stand bracket 14 870-1A237-00 Board connecting bar 15 870-10298-00 screen connecting bracket 16 Power board assy 17 808-10893-AF0 Rear cabinet baffle 18 Main board assy 19 808-10896-00 AV baffle 20 808-1A898-00 AV baffle 21 808-10812-AF0 Power lead cover 22 808-10914-AF0 speaker connecting Cover 23 615-10612-00 Stand assy 24 615-20517-00 Bottom speaker assy 25 742-30088-110 Line clasp 26 808-10894-AF0 Rear cabinet baffle 27 808-1C897-AF0 AV baffle 28 808-10892-AF0 Rear cabinet baffle 29 808-10900-AF0 Decorate left-right 30 808-10895-AF0 AV baffle 31 Rear cabinet 32 870-3B203-AF0 ButtonCoverbracket 33 Button board assy 34 High frequency board assy 35 743-1E210-8A1 Button decorate piece 36 870-10241-00 Mounting holder 37 870-10242-00 Mounting connecting bracket 38 804-20442-00 Connecting bar of screen 39 870-1A234-00 Board connecting bracket 40 870-1A230-00 Connecting bracket of screen 41 870-10236-00 Board connecting bracket

Infrared receiving board assy

603-L37T260-10 Ver.1.0

Xoceco LC-37T18, LC-37T26 Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual