Xoceco LC-37W18S Schematic

LCD TELEVISION

LC-37W18S

CONTENTS

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

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

Method of software upgrading ………………………………………….…….……………

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

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

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

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

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

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

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 alhocol 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.

Alignment instructions

1. Test equipment

PM5515 (Video signal generator) PM54200(SCART signal generator) VG-848(YUV, VGA and DVI signal generator) K-7253 (VGA signal generator) CA210 (White balancer)

2. The alignment flow chart (see below figure)

Production of data processing board and

Combined test for general assembly and aging

Connect to central signal source; check if various

TV functions (station skipping, modulate quantit

control etc), check if the output of earphone and

speaker are normal.

Input AV/S signal, SCART and HDTV signal; check various functions under AV/S terminal

Input VGA signal and check if display is normal in

the state of PC and various functions (analog

quantity control, line/field center etc.)

Fig.1 Flow process of alignment

3 Unit adjustments

Method for entering factory menu: Press MENU → -/-- →9→1→8 one by one, then enter factory menu, press the SLEEP button to select adjustment page, exit factory menu to press the MENU button.

Check DDC and FLASH

analogue board on the line.

White balance adjustment

Check accessories and then packing

4 EEPROM initialization

Enter the first page of factory menu, select “EEPROM INITIALIZE” to be “on”, after turn off the unit, repeating turn on the unit is over.

5 white balance adjustment

Input PAL signal of 16-level gray-scale (TIMING969 PATTAN921) from VG848 to AV channel, enter user menu, set color to 0, APL to “off”, enter factory menu white balance adjustment page, select color temperature, fixed the GGAIN to 50H, adjust BGIAN and RGAIN to 400nits, then the color coordinate to 284, 299. Fixed the BOFFSET to 50H, adjust GOFFSET and ROFFSET to 5nits, then the color coordinate to 284, 299. Select cool tint, adjust color coordinate to 270, 283. Select warm tint, adjust color coordinate to 313, 329.

6. Performance Inspections

6.1 TV function Enter the search menu → auto search, connect RF-TV terminal to the central signal source, check if there is station skipping.

6.2 AV/S input terminal Input AV/S signal, check the picture and sound is normal

6.3 SCART terminal (note: check the SCART terminal, set display mode to AUTO)

6.3.1 Check SCART INPUT special function

6.3.1.1 SCART1 terminal function a. After turn on the unit, connect the SCART1 to PM54200 signal generator, then the unit auto select to SCART1 mode. b. SCART signal generator sends CVBS signal to the unit, check if the image and sound is normal. It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal. Change SCART signal to RGB signal, check if the image and sound is normal, It sends image format (16:9 and 4:3) to the unit, check the unit auto identify is normal. Select the PIP mode, connect earphone cable, and check if the sound is normal.

6.3.1.2 SCART2 terminal function a. After turn on the unit, connect the SCART2 to PM54200 signal generator, then the unit auto select to SCART2 AV mode. b. SCART signal generator sends CVBS signal to the unit, check if the image and sound is normal. It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal, and display the SCART2 AV. Change SCART signal to Y/C signal, select the SCART2 Y/C channel mode, check if the image and sound is normal, It sends image format (16:9 and 4:3) to the unit, check if the unit auto identify is normal. Select the PIP mode, connect earphone cable, and check if the sound is normal.

6.3.2 Check SCART OUTPUT special function

6.3.2.1 SCART1 terminal function Input signal in the TV states, connect the SCART1 terminal to the TV. Change the TV program, check if output signal of SCART1 is TV signal, and the image and sound is normal, change the unit channel, the CART1 output TV signal, it can not other signal.

6.3.2.2 SCART2 terminal function

Input signal in the TV/AV/S states, connect the SCART2 terminal to the TV. Change the unit channel, check if output signal of SCART2 is current signal, and the image and sound is normal.

6.4 YPbPr/YPbPr terminal Input the YUV signal (VG-848 signal generator), separate input YUV format signal of table 1, check if the image and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu. If the image is slight disturb, adjust the FINE TUNE correction of the SCREEN menu. Open the PIP mode, connect the earphone, and check if the image and sound is normal.

Table 1 YUV format signal

H-frequency(kHz) V-frenquency(Hz) signal 1 15.734 59.94 SDTV 480i

2 31.469 59.94 HDTV 480p 4 44.955 59.94 HDTV 720p 6 33.716 59.94 HDTV 1080i 7 15.625 50 SDTV 576i 8 31.25 50 HDTV 576p 9 33.75 50 HDTV 1080i

10 37.50 50 HDTV 720p

6.5 VGA terminal

Input the VGA signal (VG-848 signal generator), separate input VGA format signal of table 1, check if the image and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu. If the image is slight disturb, adjust the FINE TUNE correction of the SCREEN menu. Open the PIP mode, connect the earphone, and check if the image and sound is normal.

6.6 HDMI terminal HDMI signal format receive the three high definition signal: 480P, 576P, 720P/50/60 Hz, 1080I/50/60 Hz, except for the table 2 signal. Check if the image (contain HDCP ON and OFF) and sound is normal. If the image is deflection of the H-field, select auto sync correction of the SCREEN menu. Open the PIP mode, connect the earphone, and check if the image and sound is normal.

TABLE2 VGA signal format

resolution H-frequency(kHz) V-frenquency(Hz)

Point clock pulse

frenquency(MHz)

remark

1 720 X 400 31.469 70.086 28.322 IBM 2 640 X 480 31.469 59.94 25.175 IBM 3 640 X 480 37.861 72.809 31.5 VESA 4 640 X 480 37.5 75 31.5 VESA 5 640 X 480 43.269 85.008 36 VESA 6 800 X 600 35.156 56.25 36 VESA

7 800 X 600 37.879 60.317 40 VESA 8 800 X 600 48.077 72.188 50 VESA

9 800 X 600 46.875 75 49.5 VESA 10 800 X 600 53.674 85.061 56.25 VESA 11 1024 X 768 48.363 60.004 65 VESA

12 1024 X 768 56.476 70.069 75 VESA 13 1024 X 768 60.023 75.029 78.75 VESA

14 1280 X 1024 63.98 60.02 108.00 VESA 15 1024 X 768 68.667 84.98 94.486 VESA

6.7 ex-factory setting see to TABLE 3 - TABLE 9

TABLE 3 Factory Option Menus

Items Ex-factory setting

IIC Bus-off Off

EEPROM Erase Off

Backlight Adjustable Off

Back Light 100

Menu Timeout 5

Blank switch enable On

ShowLogo On

Auto Program Sort On

TT Char Group

West Europe / East Europe / Cyrillic / Turkish

/Greek/Arabic/Hebrew Dynamic Scart Off Note: the latter 6 items should set according to clients’ require.

TABLE 4 Factory Audio Setting

Items

Ex-factory setting

LC-27W18S/27W25S LC-32W25S LC-37W25S LC-42W17S

Volume 1 2CH 2CH 2CH 2CH Volume 25 55H 57H 5AH 5AH Volume 50 5CH 5EH 61H 61H Volume 75 64H 65H 69H 69H Volume 100 6BH 6DH 72H 72H

HP VOLUME SETTING

Volume 1 64H Volume 25 96H Volume 50 A1H Volume 75 AEH Volume 100 BEH MSP Scart1 Volume 72H

Prescale Scart 4CH Prescale FM/AM 27H Prescale Nicam 64H

Scart TV Volume 20H

Scart AV Volume 72H

D/K select HDEV3 Off AVC Of f

Equalizer Bands Max 60H Spatial Mode 0 Spatial Strength 00H

TABLE 5 Factory Video limit Setting

Items CVBS SC-RGB YPBPR D-SUB HDMI Bright Min D5H CFH C7H CFH D2H

Bright Middle 00H 00H 03H 05H 07H Bright Max 38H 3DH 34H 3DH 31H

Contrast Min 09H 09H 09H 09H 08H Contrast Middle 20 25H 20H 25H 23H Contrast Max 2AH 31H 29H 31H 2CH

Sharpness Min 00H 00H 00H 00H 00H Sharpness Middle

10H 10H 10H 10H

10H

Sharpness Max 1FH 1FH 1FH 1FH 1FH

Color Min 00H 00H 00H 00H 00H

Color Middle 1DH 1DH 1DH 1DH 1DH Color Max 2DH 2DH 2DH 2DH 2DH

Hue Min 80H 80H 80H 80H 80H Hue Middle 20H 20H 20H 20H 20H Hue Max 7FH 7FH 7FH 7FH 7FH

TABLE 6 White Balance Adjust

Items LC-27WXXS LC-32WXXS LC-37WXXS LC-42WXXS R Offset 55 55 54 53 G Offset 51 53 57 49 B Offset 50 50 50 50 R Gain 42 36 36 37

G Gain 50 50 50 50 B Gain 21 40 51 38 Brightness 51 51 51 51 Contrast 100 100 100 100 Color Temperature Standard

R Offset 60 59 58 55 G Offset 55 55 58 52

B Offset 50 50 50 50 R Gain 35 25 24 32

G Gain 50 50 50 50 B Gain 28 48 61 48 Brightness 51 51 51 51 Contrast 100 100 100 100 Color Temperature Cold

R Offset 55 49 49 44 G Offset 53 51 53 47 B Offset 50 50 50 50 R Gain 62 51 58 66 G Gain 50 50 50 50 B Gain 8 23 33 22

Brightness 51 51 51 51 Contrast 100 100 100 100 Color Temperature Warm

TABLE 7 Image analog setting

CVBS Vivid Standard Mild Custom Contrast 90 80 50 80

Brightness 40 35 35 35 Color 70 60 40 60 Hue 00 00 00 00 Sharpness 60 50 30 50

SC-RGB Vivid Standard Mild Custom Contrast 90 85 50 85

Brightness 60 50 35 50 Color 80 65 40 65 Hue 00 00 00 00 Sharpness 60 50 30 50

YPBPR Vivid Standard Mild Custom Contrast 90 85 50 85

Brightness 50 40 35 50 Color 80 65 40 65 Hue 00 00 00 00 Sharpness 60 50 30 50

D-SUB Vivid Standard Mild Custom Contrast 90 80 50 80

Brightness 50 40 35 40 Color 80 65 40 65 Hue 00 00 00 00 Sharpness 60 50 30 50

HDMI Vivid Standard Mild Custom Contrast 90 80 50 80

Brightness 50 35 35 35 Color 80 70 40 70 Hue 00 00 00 00 Sharpness 60 50 30 50 Note: in factory menu states, it can change the factory mode to value of the image and sound, else select the image and sound balanced value in the other states.

TABLE9 SOUND equilibrium value setting

Live Pop Rock Custom 120 Hz 50 50 65 50 500 Hz 50 50 55 50

1.5 kHz 50 60 55 50 5 kHz 80 70 55 50 10 kHz 85 70 55 50

6.8 Ex-factory setting of user menu

6.8.1 select TV channel

6.8.2 video menu, Mode: Standard, NR: Medium, APL:ON

6.8.3 sound menu, Volume: 20, Balance: 00, Equalizer: Custom, HP Volume: 20;

6.8.4 edit menu, Color System: Auto, Sound System: DK;

6.8.5 option menu, Default Zoom: Auto, Child Lock: Off, Menu Language: English, Country: UK, WSS: OFF, Blue Screen: On. Note: the 6.8.4 and 6.8.5 items should set according to clients require.

Method of software upgr adi ng

1. Enter the software upgrading state of the TV Method 1: press the VOL- button in the unit, turn on the main power switch, then the screen

display black screen, but the indicator to blue.

Method 2: Enter factory menu, select the IIC-BUS OFF item.

2. Connection upgrading tools with upgrading port.

3. Dual- click IAPWriter logo, enter the upgrading states (if the PC and the IIC communication

trouble, it can prompt.

4. Select the file menu load the software follow as:

5. Select WRITE DEVICE item of the device menu, till the right screen display “DONE”.

6. turn off the power , restart the unit. Note: because of the software, it may be no-stabilization, the software can auto download and write.

Upgrading tools

Connection cable

Upgrading port

NOTE: Do not shut the power off or turn the TV set on during the FLASH write. Otherwise it may lead to no way for flash to rewrite.

Working principle analysis of the unit

1. Analog signal flow Antenna reception signal send to integrative tuner (contain HF and IF amplifier circuit), the tuner is controlled the command (SDA and SCL) of the MCU N301 (M16C), select appropriate channel to system switch, via HF amplifier and IF amplifier decode, output video signal of 2VPP and sound signal of 1VPP. Sound signal (SCART1, 2 sound, AV sound, YPbPr, HDMI and D-SUB) via N581 HEF4052BT (sound diverter switch) to output signal, it send to N801(MPS3410 sound processing and volume control) switch of audio. Select right/left sound channel, their send to digital sound amplifier N803 (TPA3008) amplify, then send to speaker. After output video signal of tuner, SCART1 video signal and RGB signal via matched resistance, the signal thought alone channel send to main decode IC(N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS level drive for LCD screen. AV, S-Video, SCART2 video and Y/C signal thought matched resistance, the signal send to the N506 video switch (SN74CBT3257CDR), via switching to selected signal (EX52_Y and EX52_C) to main decode IC (N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then send to LVDS level drive for LCD screen. D-sub and YPbPr signal thought matched resistance, the signal send to the N507 video switch (SN74CBT3257CDR), via switching to selected signal (EX52_YUV) to main decode IC (N101 SVP-EX52) video switch, A/D transition, digital decode, image scale and OSD superposition, then

send to LVDS level drive for LCD screen.

2. Digital signal flow: HDMI signal thought HDMI reception chip N405 (SiI9011HDMI with HDCP function), after receive, output digital format signal send to SVP-EX52 PIP channel thought image scale and OSD superposition, then send to LVDS level drive for LCD screen. The HDMI chip output audio digital format signal change to analog sound signal from N403 (CS4344 audio DA transfer chip), then N581 switched to N801 (MPS3410 sound processing and volume control).

3. TELETEXT function This unit adopt main decode IC N101(SVP-EX52) of Trident company, it has TELETEXT decode function, after decoded, the teletext information in OSD display.

Block diagram

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