AOC LV20E351 Schematic

20" LCD TV Color Monitor LV20E351

Service

Horizontal Frequency

31.5-49kHz

TABLE OF CONTENTS

Description Page Description Page

Table Of Contents.......……..............................…........1

Revision List.…........................................……......2

Important Safety Notice.……..................……......3

1.Specification For LCD-TV……....................………........4

1.1 General Specification…………………………….......4

1.2 LCD-TV Description..…………...............…….........5

1.3 Interface Connector.........…...........…..…...........5

2. Precautions And Notices…............…................5

2.1 Assembly Precaution...........................…............5

2.2 Operating Precaution…............……………..........5

2.3 Storage Precaution….…........………..…...............5

2.4 High Voltage Warning…………….…….…………….5

3. Input/Output Specification…………………………….6

SAFETY NOTICE

4. Adjustments………….……..............................……….7

5. Trouble Shooting………………………………………..14

6.White-Balance, Luminance Adjustment……………….20

7.Block Diagram………..…....………..............................22

7.1 Main Board……….…...……………..………..............22

7.2 Power Board……………...….……………………..….23

8.Schematic………………..…....…..............................24

8.1 Main Board..…..……………......................................24

8.2 Power Board…….....…..……....................................37

9. Explode View…………………………………………….41

10. BOM List..…………..........………………….……......42

11.PCB Layout..…….……..........………………….…......67

11.1 Main Board.……….…………………….…… ...........67

11.2 Power Board.…..……………..………..…......….......69

ANY PERSON ATTEMPTING TO SERVICE THIS CHASSIS MUST FAMILIARIZE HIMSELF WITH THE

CHASSIS AND BE AWARE OF THE NECESSARY SAFETY PRECAUTIONS TO BE USED WHEN SERVICING

ELECTRONIC EQUIPMENT CONTAINING HIGH VOLTAGES.

CAUTION: USE A SEPARATE ISOLATION TRANSFOMER FOR THIS UNIT WHEN SERVICING

Revision List

Revision Release Date Revision History TPV Model

A00 Jun-06-06 Initial Release EAB5ASNBC3VDTM

Important Safety Notice

Proper service and repair is important to the safe, reliable operation of all AOC Company Equipment. The service

procedures recommended by AOC and described in this service manual are effective methods of performing service

operations. Some of these service operations require the use of tools specially designed for the purpose. The special

tools should be used when and as recommended.

It is important to note that this manual contains various CAUTIONS and NOTICES which should be carefully read in

order to minimize the risk of personal injury to service personnel. The possibility exists that improper service methods

may damage the equipment. It is also important to understand that these CAUTIONS and NOTICES ARE NOT

EXHAUSTIVE. AOC could not possibly know, evaluate and advise the service trade of all conceivable ways in which

service might be done or of the possible hazardous consequences of each way. Consequently, AOC has not

undertaken any such broad evaluation. Accordingly, a servicer who uses a service procedure or tool which is not

recommended by AOC must first satisfy himself thoroughly that neither his safety nor the safe operation of the

equipment will be jeopardized by the service method selected.

Hereafter throughout this manual, AOC Company will be referred to as AOC.

WARNING

Use of substitute replacement parts, which do not have the same, specified safety characteristics might create shock,

fire, or other hazards.

Under no circumstances should the original design be modified or altered without written permission from AOC. AOC

assumes no liability, express or implied, arising out of any unauthorized modification of design.

Servicer assumes all liability.

FOR PRODUCTS CONTAINING LASER:

DANGER-Invisible laser radiations when open AVOID DIRECT EXPOSURE TO BEAM.

CAUTION-Use of controls or adjustments or performance of procedures other than those specified herein may result

in hazardous radiation exposure.

CAUTION -The use of optical instruments with this product will increase eye hazard.

TO ENSURE THE CONTINUED RELIABILITY OF THIS PRODUCT, USE ONLY ORIGINAL MANUFACTURER'S

REPLACEMENT PARTS, WHICH ARE LISTED WITH THEIR PART NUMBERS IN THE PARTS LIST SECTION OF

THIS SERVICE MANUAL.

Take care during handling the LCD module with backlight unit

-Must mount the module using mounting holes arranged in four corners.

-Do not press on the panel, edge of the frame strongly or electric shock as this will result in damage to the screen.

-Do not scratch or press on the panel with any sharp objects, such as pencil or pen as this may result in damage to the

panel.

-Protect the module from the ESD as it may damage the electronic circuit (C-MOS).

-Make certain that treatment person’s body is grounded through wristband.

-Do not leave the module in high temperature and in areas of high humidity for a long time.

-Avoid contact with water as it may a short circuit within the module.

-If the surface of panel becomes dirty, please wipe it off with a soft material. (Cleaning with a dirty or rough cloth may damage the panel.)

1. Specifications For LCD TV

1-1 General Specifications

20.1” screen

Feature

SVGA ( 800 x 600 ) Resolution High Brightness ( 500 cd/m High Contrast Ration ( 500:1 ) Wide Viewing Angle ( 160 H / 160 V ) Built-in Full channel Tuner with Nicam, Teltext. Graphic (VGA) PIP(Video on Graphic)

)

Items

Screen Size 20.1” TFT-LCD Panel (AU) Aspect Ratio 4:3 Resolution

Display Area (opening) H x V Pixel Pitch

LCD Panel

TV Function

Graphic (VGA)

Audio Output

Other Function OSD language

Table Stand Wall Mount

Power

Panel Tilt Dimension

Weight (net) Kg (w/o Accessories) 9KG

Accessories

Video/Audio Inputs

Display colors 16.7 million Contrast Ratio 500:1 Brightness 500cd /m2 Viewing Angle Response Time 16ms

Lamp Type/Life 60000 hr

Color Temperature Cold/Warm

TV Tuning System

Sound System Nicam / A2 Tel te x t Ye s Color systems PAL / SECAM / NTSC

Signal Input Analog: D-Sub 15 pin (detachable cable) PnP compatibility DDC / 2B

Input frequency

Recommended Analog: 800 x 600 (60Hz) Input Audio Headphone Mini-jack for stereo (3.5ø)

Audio Output: L / R

PIP, Wireless Headphone (Option), DPF -Digital Photo Frame (Option)

English/Italian/Spaish/German/French/ Portuguese

Included VESA 100 x 100 mm

Power Supply AC100V~240V, 50/60Hz Power Consumption <70W Forwards/Backwards/ Rotation

W x H x D (with stand) 696 x 443 x 250 (mm)

Remote Controller, Batteries (x2), AC Power Cord, User Manual SCART RCA

S-Video

Specification

800 × 600 (SVGA) 408mm × 306mm

0.51mm × 0.51mm

160°(Horizontal) / 160°(Vertical)

PAL B/G, D/K, I and SECAM L/L’ (Multi-Europe) Full Channel with Electronic PLL Tuner

Analog: FH: 31.5KHz to 48KHz FV: 56Hz to 75Hz

Speaker (built-in): Two 2 watt speakers

Headphone Mini-jack for stereo (3.5ø)

Line Output (RCA L/R)

-5°/ +20°/ ± 30°

RGB or CVBS ×1 Audio L/R ×1 CVBS (Composite) ×1 Audio L/R ×1

S-Video×1

Share with CVBS (RCA)

1-2 LCD TV Description

The LCD TV will contain a main board (include audio), a switching power board (include an inverter board), an IR board, a function keyboard, and an Earphone board. The main board and power board will house the flat panel to control logic I2C bus, DDC, brightness control logic for LCD panel, DC-DC conversion to supply the appropriate power to the whole board and transmitting TTL level signals into LCD Module to drive the LCD display circuit. The inverter board will drive the six CCFLs (Cold Cathode Fluorescent Tube). The switching power board will provides the power ON/OFF to control the TV and control LED indicator for DPMS. The function keyboard and Remote Control will provide the OSD control signal to the Main Board.

1-3 Interface Connector

(A) Power Cord Connector.

(B) RF Signal Connector. (C) Video (SCART, AV2, S-VIDEO) / Audio Signal Connectors.

(D) PC D-sub 15 pin Connector. (E) PC Audio Connector.

2. Precautions And Notices

2-1 Assembly Precaution

(1) Please do not press or scratch LCD panel surface with anything hard. And do not soil LCD panel surface by

touching with bare hands (Polarize film, surface of LCD panel is easy to be flawed)

In the LCD panel, the gap between two glass plates is kept perfectly even to maintain display characteristic

and reliability. If this panel is subject to hard pressing, the following occurs: (a) Uniform color (b) Orientation of liquid crystal becomes disorder (2) Please wipe out LCD panel surface with absorbent cotton or soft cloth in case of it being soiled. (3) Please wipe out drops of adhesive like saliva and water in LCD panel surface immediately.

They might damage to cause panel surface variation and color change. (4) Do not apply any strong mechanical shock to the LCD panel.

2-2 Operating Precaution

(1) Please be sure to unplug the power cord before remove the back-cover. (be sure the power is turn-off) (2) Please do not change variable resistance settings in MAIN-BOARD; they are adjusted to the most suitable

value. If they are changed, it might happen LUMINANCE does not satisfy the white balance spec. (3) Please consider that LCD backlight takes longer time to become stable of radiation characteristic in low

temperature than in room temperature. (4) Please pay attention to displaying the same pattern for very long-time. Image might stick on LCD.

2-3 Storage Precaution

(1) When you store LCD for a long time, it is recommended to keep the temperature between 0℃-40℃ without

the exposure of sunlight and to keep the humidity less than 85% RH.

(2) Please do not leave the LCD in the environment of high humidity and high temperature such as 60℃,

85%RH.

(3) Please do not leave the LCD in the environment of low temperature; below -25°C.

2-4 High Voltage Warning

The high voltage was only generated by INVERTER module on Power Board, if carelessly contacted the transformer on this module, can cause a serious shock. (the lamp voltage after stable around 600V, with lamp current around 8mA, and the lamp starting voltage was around 1500V, at Ta=25°C)

3. Input/Output Specification

This procedure gives you instructions for installing and using the LCD TV display.

1. Position the display on the desired operation and plug the power cord into a convenient AC outlet. Three-wire power cord must be shielded and is provided as a safety precaution as it connects the chassis and cabinet to the electrical conduct ground. If the AC outlet in your location does not have provisions for the grounded type plug, the installer should attach the proper adapter to ensure a safe ground potential.

2. Connect the 15-pin color display shielded signal cable to your signal system device and lock both

screws on the connector to ensure firm grounding. The connector information is as follow:

Pin No. Description Pin No. Description

1. RED Video 9. NC

2. GREEN Video 10. Sync Ground

3. BLUE Video 11. RXD (for ISP)

4. TXD (for ISP) 12. Serial Data for DDC

5. Ground 13. HORIZ. SYNC

6. Ground-R 14. VERT. SYNC

7. Ground-G 15. Serial Clock for DDC

8. Ground-B

Factory Preset Display Modes:

Analog RGB Signal Timing

Horizontal Vertical

Mode Resolution

11 15

15 - Pin Color Display Signal Cable

VESA MODES

Nominal

Frequency

Sync

Polarity

(KHz)

Nominal

Freq.

(Hz)

Sync

Polarity

DOS

720x400@70Hz 31.5 N 70.1 N

640x480@60Hz 31.469 N 59.940 N

640x480@72Hz 37.861 N 72.809 N 640x480@75Hz 37.500 N 75.00 N 800x600@60Hz 37.879 P 60.317 P

800x600@72Hz 48.077 P 72.188 P 800x600@75Hz 46.875 P 75.000 P

4. Adjustment

4-1 Adjustment Control Function

Adjustments items as below:

External Controls: (7-key knob) Menu, CH Down, CH Up, Power On/Off, VOL Down, VOL Up, Source OSD Control function:

To Use The Menus

TO USE THE MENUS

1. Press the MENU button repeatedly to display each menu.

2. Use the cursor up/down to select a menu item or adjust the setting of Menu item.

3. Use the cursor left/right to enter a submenu or enable the function.

4. Press the MENU button to exit the menu.

MAIN MENU

Press the MENU button into the main OSD (On Screen Display). Adjust item include VIDEO, AUDIO, TV (only in the TV mode), PC and PIP (only in the PC mode) and SETUP.

1. CONTRAST, BRIGHTNESS, COLOUR and TINT are adjusted from 0 to 100.

2. BLACK LEVEL is adjusted from 0 to 100.

3. SHARPNESS is adjusted from -5 to+5. You can adjust picture contrast, brightness, color, tint and sharpness to the levels you prefer.

4. RESET is set up to default value.

VIDEO Adjust

Note: TINT only work in NTSC video signal input.

When adjust any item sub-OSD will show up like this.

AUDIO Adjust

1. VOLUME is adjusted from 0 to 100.

2. BASS and TREBLE are adjusted from 0 to 100. You can adjust picture Volume, Bass and Treble to the levels you prefer.

When adjust any item sub-OSD will show up like this.

3. SRS for turn on / off SRS function. SRS is audio technology makes everything sound better.

Quick Installation

1. Use COUNTRY to select your country first.

2. Move to SCAN and scan the program.

3. After scan finished, user can use SKIP to skip the unlike program.

PROGRAM Editing

Using PROGRAM, FREQENCY, SWAP, and INSERT for program edit.

1. Move to PROGRAM, select the program you want to edit

2. Move to FREQENCY, use RIGHT or LEFT button for program search.

3. User can use SWAP for program swap.

4. Use INSERT to insert current program into selected position.

SETUP

1. BLUE SCREEN for when no video input screen will be blue or blank. If it’s ON, the screen will be in blue. If it’s OFF,

the screen will be blank. Preset is ON.

1. LANGUAGE for different language OSD MENU. Preset is English.

2. SLEEP TIMER is for set a time period after which the TV should switch itself to standby. The counter runs from 0 >

30 > 60 > 90 > 120 minutes.

3. RESET is set up to default value of BLUE SCREEN and SLEEP TIMER.

Note: To view the remaining time, press the SLEEP button once. To cancel the sleep time, repeatedly press the SLEEP button until… APPEARS. If you turn the TV off after setting the sleep time, the setting will be erased. Set it again.

PC Setup

PC Adjust

1. AUTO TUNE is the function auto-sizing for VGA input.

2. CONTRAST, BRIGHTNESS, FOCUS, CLOCK, H-POSITION, V-POSITION and COLOUR are the functions for

PC adjustment.

Colour for you can adjust the colour temperature you prefer.

COLOUR

PIP

1. PIP for turn on / off small picture function.

2. POSITION for change the position of small picture.

3. SOURCE for select video source of small picture.

4. SOUND for select audio source form MAIN (PC) or SUB (Video).

Input Source Select:

Press repeatedly Source button to select TV, AV1, SCART, S-VIDEO or PC mode.

Use of the remote control

USE OF THE REMOT CONTROL

TELE

POWER:

Press to turn on/off the TV. The TV is never completely powered off unless it is physically unplugged.

Press or (or MENU ▲ or ▼ button) to brows through the TV channels which

Press + or – (or MENU

or button) to

Select your input source to PC.

SLEEP

With this key you can set a time period after which the TV should switch itself to standby. Press the key repeatedly to select the number of minutes. The counter runs from 0,30,60,90,120 minutes. The timer begins to count down from the number of minutes selected after the display has disappeared.

SWAP

Press to swap the two screens when PIP is work (option).

MENU Press repeatedly

to display OSD menu.

SIZE

Includes 3 modes. Press repeatedly to select 4:3: to

16:9 (Linear) / 4:3 to 16:9 (non-Linear) /16:9 (option).

DISPLAY

(1) Display Channel number

when use RF input.

(2) Display input source when

use other input except TV RF in

ut.

MUTE

Temporarily interrupt the sound or restore it.

SUBPAGE

Teletext Subpage function.

0~9 DIGIT BUTTONS

To select a TV channel.

PRE-CH

To display the previously selected TV channel.

TV/VIDEO

Select your input source: press repeatedly to select TV, AV, S-VIDEO or SCART mode, according to where you connected your external source.

SOUND

To select Mono/ Stereo /Dual from TV RF input.

PIP/POP

Press to enable the screen of Video on Graphic (option).

TELETEXT

Teletext is an information service organized like a magazine, which is provided by some TV stations in addition to

regular television broadcasting.

TELETEXT

Press TELETEXT. The Teletext screen appears. To turn off the Teletext mode, press TELETEXT again.

MIX

Press MIX to superimpose the teletext over a normal broadcast picture. Press again to return to Teletext mode.

SIZE

Press SIZE repeatedly to display the upper teletext part, the lower teletext part and then to return to the normal.

Red / Green / Yellow / Blue

Use the COLORED BUTTONS to operate the Teletext screen.

INDEX

Press INDEX to return to the main index page.

SUBTITLE

Press to select the next page marked as a subtitle page and request it as the display p

age.

HOLD

Press HOLD to hold the Teletext page when viewing information. Press again to return to automatic page update.

REVEAL

Press REVEAL to display reveal hidden words e.g. quiz page answers. Press again to hide.

Page selection

Page can be selected in two ways. a. Press ▼or ▲ to increase or decrease the page number by one. b. B

entering the page number, using digit buttons 0~9.

Subpage Access

When Teletext information exceeds more than on page. Press SUBPAGE first then select the required page number using digit buttons 0~9.

4-2 Adjustment Method

Press MENU key to show OSD window or exit, Up / Down key to done the function selection, And + / - key to done the adjustment.

4-3 Front Panel Control Knobs

Power Key： Press to turn on or off the TV. MENU Key：Press to show the OSD menu and exit OSD menu at the TV. CH Down / Up Key：Press to perform select function and channel. VOL - / + Key：Press to confirm your function selection and adjustment. Source Key：Press to select your input source.

)

5. Trouble Shooting

5-1 Panel Control Circuit

No Display

Check CN101 pin 42-45 is 5V and signal on pin 35,37,39,40,25-28,30-33,1518,20-23,5-8,10-13

Check U300 Output to

CN101 relative circuit and

CN101 VCC at Q300,

Q301

Check U300 crystal

X300 (12MHZ)

L309 (5V

Replace panel or FFC cable to panel

Replace L118, C137

Replace X300

Check 2.5V L301-L304

33..33VV LL330055--LL330088

Replace U300

Replace components if it has problem

5-2. Main Board Power Circuit

5-3. Remote Control Block

5-4. Key Board Control Block

5-5. Pc Control Block

5-6. Audio Control Block

5-7 Video Control Block

Note: 1、If Replace “MAIN-BOARD” , Please re-do “DDC-content” programmed & “WHITE-Balance”.

2、If Replace “ POWER-BOARD INVERTER” only, Please re-do “ WHITE-Balance” 3、Please re-install program before you do change any component.

6. White-Balance, Luminance Adjustment

Approximately 30 minutes should be allowed for warm up before proceeding white balance adjustment.

Before started adjust white balance, please setting the Chroma-7120 MEM. Channel 1 to 9300 colors, MEM. Channel 2 to 6500 color, and MEM. Channel 3 to 9300 colors, (9300 parameter is x = 283 ± 15, y = 297 ± 15, Y =

SPC. ± 7 cd/m2; 6500 parameter is x = 313 ± 15, y = 329 ± 15, Y = SPC.± 7 cd/m

PC PC AV

Color Temp. 9300 6500 9300

x 0.283 0.313 0.283 y 0.297 0.329 0.297

250±7 250±7 290±20

How to setting MEM.channel you can reference to Chroma-7120 user guide or simple use “ SC” key and “ NEXT” key to modify x,y,Y value and use “ID” key to modify the TEXT description

Following is the procedure to do white-balance adjust

˙Press Number key 100 Æ 9 Æ 9 Æ 9 will into the factory mode, and press Menu key the OSD will show menu and a

word F at Right top of Menu.

˙In the factory mode select MORE function will into Bias and Gain adjustment.

1. ADC Adjustment: AL Æ Auto level adjust. RG, GG, BG Æ R, G, B Gain adjusts.

RB, GB, BB Æ R, G, B Bias adjusts.

2. SCALER Adjustment: CO, BR Æ Contrast and Brightness adjust. RG, GG, BG Æ R, G, B Gain adjusts. RB, GB, BB Æ R, G, B Bias adjusts. S9, S6, ST, SH Æ Save 9300, 6500, 9300 color temperature. R9, R6, RT, RHÆ Recall 9300, 6500, 9300-color temperature. BI Æ Setup Burn-in mode ON / OFF. ISP ÆSet ISP ON/OFF. PP Æ Set PIP ON/OFF. WH Æ Set Wireless Headphone ON/OFF. SR Æ Set SRS ON/OFF. CC Æ Set Close Caption ON/OFF. VC Æ Set V Chip ON/OFF. EX Æ Exit MORE function to factory mode menu.

II. Bias (Low luminance) adjustment:

1. Press “ AUTO” button,

2. Set the contrast on OSD window to the value=51, color (user) R, G, B set to “50”

3. Adjust the brightness on OSD until chroma 7120 measurement reach the value Y>390 cd/m

III. Gain adjustment:

A. Adjust 9300 color-temperature:

1. Set the Contrast of OSD function to 45 and Adjust Brightness to chroma-7120 Y>230 cd/m

2. Switch the chroma-7120 to RGB-mode (with press “MODE” button)

3. Switch the MEM.channel to Channel 01 (with up or down arrow on chroma-7120)

4. The lcd-indicator on chroma-7120 will show x = 283 ± 15, y = 297 ± 15, Y =250 ± 7 cd/m

5. Adjust the Color(user)Mode: RED on OSD window, until chroma 7120 indicator reached the value R=100

6. Adjust the Color (user) Mode: GREEN on OSD window, until chroma-7120 indicator reached the value G=100

7. Adjust the Color (user) Mode: BLUE on OSD window, until chroma-7120 indicator reached the value B=100

8. Repeat above procedure (Item 5,6,7) until chroma-7120 RGB value meet the tolerance =100±2

9. Switch the chroma-7120 to xyY mode With press “MODE” button

10. Press Color (9300) on OSD window to save the adjustment result

B.Adjust 6500 color-temperature:

)

1. Set the Contrast of OSD function to 45 and Adjust Brightness to chroma-7120 Y>230 cd/m

2. Switch the chroma-7120 to RGB-mode (with press “MODE” button)

3. Switch the MEM.channel to Channel 02 (with up or down arrow on chroma-7120)

4. The lcd-indicator on chroma-7120 will show x = 313 ± 15, y = 329 ± 15, Y = 250 ± 7 cd/m

5. Adjust the Color (user) Mode: RED on OSD window, until chroma 7120 indicator reached the value R=100

6. Adjust the Color (user) Mode: GREEN on OSD window, until chroma-7120 indicator reached the value G=100

7. Adjust the Color (user) Mode: BLUE on OSD window, until chroma-7120 indicator reached the value B=100

8. Repeat above procedure (item 5,6,7) until chroma-7120 RGB value meet the tolerance =100 ± 2

9. Switch the chroma-7120 to xyY mode with press “MODE” button

10.Press Color (6500) on OSD window to save the adjustment result

C. Adjust 9300 color-temperature:

1. Set the Contrast of OSD function to 45 and Adjust Brightness to chroma-7120 Y>280 cd/m

2. Switch the chroma-7120 to RGB-mode (with press “MODE” button)

3. Switch the MEM.channel to Channel 03 (with up or down arrow on chroma-7120)

4. The lcd-indicator on chroma-7120 will show x = 283 ± 15, y = 297 ± 15, Y = 290 ± 20 cd/m

5. Adjust the Color (user) Mode: RED on OSD window, until chroma 7120 indicator reached the value R=100

6. Adjust the Color (user) Mode: GREEN on OSD window, until chroma-7120 indicator reached the value G=100

7. Adjust the Color (user) Mode: BLUE on OSD window, until chroma-7120 indicator reached the value B=100

8. Repeat above procedure (item 5,6,7) until chroma-7120 RGB value meet the tolerance =100 ± 2

9. Switch the chroma-7120 to xyY mode with press “MODE” button

10. Press Color (9300) on OSD window to save the adjustment result

Turn the POWER-button off to on to quit from factory mode (in USER-mode, the OSD window location was placed at middle of screen)

+ 49 hidden pages