AOC N20S651 Schematic

20” LCD TV No Brand N20S651

Service

Horizontal frequency

31.5 kHz to 48 kHz

TABLE OF CONTENTS

Description Page Description Page

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

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

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

1. Monitor Specification..…............................………........4

2. Operating Instructions……...……………….……….......5

2.1 The Use Of Remote Control..…………..................5

2.2 Front Panel Control Knobs.....................…...........7

2.3 OSD Operating…………….…............……...............8

2.4 How To Connect...………........................…............12

3. Input/Output Specification............……………............14

3.1 Input Signal Connector............………….................14

3.2 Factory Preset Display Modes........………...............14

4. Mechanical Instructions..………....……......................16

5. Repair Flow Chart…….……………………..................20

6. PCB Layout………...……….……………....….…….....26

6.1 Main Board……...……………..……………....….......26

6.2 Power Board………………………….....….......27

6.3 Key Board….….........................................…….........28

6.4 Tuner Board...………...…...................................29

6.5 Earphone board……………………...……..………30

7. Block Diagram..……..……................….......................31

7.1 Main Board...............……..……...............................31

7.2 Power Board…...……..….…...….…..........................32

8. Schematic Diagram…….….….………………….......33

8.1 Main Board……...…..……….………......................33

8.2 Power Board...……………….……………………...45

8.3 Key Board……………..…………..………………...48

8.4 Tuner Board.....…..........……………........................49

8.5 IR Board...…….........…………...............................53

9. Exploded View…….........………..............…................54

10. BOM List…………………… …….....……….…..........56

SAFETY NOTICE

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

20” LCD TV No Brand N20S651

Revision List

Version Release Date Revision History TPV Model

A00 Mar.-30-2006 Initial Release E206CHNBD1GSNP

20” LCD TV No Brand N20S651

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 may 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 radiation 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.)

20” LCD TV No Brand N20S651

1. General Specifications

Item Spec

Screen Size 20” TFT-LCD Panel

Aspect Ratio 4 : 3

Resolution 640 x480 (XGA)

Display Area (opening) H x V 408mm x 306mm

Pixel Pitch 0.6375mm x 0.6375mm

Display Colors 16.2 million

LCD Panel

Contrast Ratio 500:1

Brightness 450 cd/m2

Response Time 12ms

Viewing angel 160° H/ 160°V

Lamp Type/Life 50000 hr

Color Temperature Cold / Warm/Normal

Input support definition 640*480 /60Hz

VGA Function

Audio input Mini jack for stereo headphones (3.5ø)

TV Standard SECAM PAL

TV Function

Video Input

Audio output

OSD Language

Table Stand Yes

Wall Mount VESA 100 x 100 mm

Power

Panel Tilt

Environment Temperature + 0 °C ~ + 40 °C

Color systems SECAM L/L’ PAL BG/DK/I

Sound System Mono, Nicam stereo, A2

AV RCA x 1

S-VIDEO

SCART

Audio output: L / R

English，France，Deutsch，Spanish，Portugese，Polish, Russian，Italian，Finnish， Swedish

Power AC100V-240V, 50/60Hz

Power Consumption <70W

Forwards/Backwards/ Rotation

S-Videox 1 CVBS/R GB

Speaker (built-in): Two 2 watt speakers

Headphone Mini-jack for stereo (3.5ø)

Audio L/R x 1

-4°/ +18° / ± 35°

storage - 25 °C ~ + 60 °C

operating 10% ~ 85%

Dimension W x H x D (with stand) 498 x 495 x 185 (mm)

Net weight Without accessory 9.5 Kg

20” LCD TV No Brand N20S651

2. Operations Instructions

2.1 The Use of Remote Control

POWER:

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

Press MENU ▲ or ▼ button) buttons to scroll through the channels. VOL Press + or – (or MENU button) to increase or decrease the volume.

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 to 120 minutes. The timer begins to count down from the number of minutes selected after the display has disappeared.

SWAP

SWAP is not available on this model.

Teletext function and buttons will be described on next page.

or (or

Press this key to display or exit main menu.

Size

Size is not available on this model.

DISPLAY

Press this key to

display:

(1) the channel

number when watching a TV program.

(2) the input source

when watching the other video

MUTE

Temporarily interrupt the sound or restore it.

SUBPAGE

Teletext Sub-page function.

0~9 DIGIT

BUTTONS

To s el ec t a TV channel.

PRE-CH

To display the previously selected TV channel.

SOUND

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

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.

PIP/POP PIP/POP is not

available on this model.

20” LCD TV No Brand N20S651

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 COLOURED 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 page.

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

20” LCD TV No Brand N20S651

2.2 Front Panel Control Knobs

Power Key ⑦ : Press to turn on or off the TV. MENU Key ⑥ : Press to show the OSD menu and exit OSD menu at the TV. CH Down / Up Key ⑤ ④: Select the intended function by pressing these two keys, or switch the channels in the

TV mode.

Vol + /- Key ② ③: Press to confirm your function selection and adjustment

volume.

Source Key ① : Press to select your input source.

Lay the LCD TV with the screen down on a table, as it will be easier to connect your peripheral equipment. Please take your precautions not to damage the screen.

1: AC power input terminal

2: VGA input

3: VGA audio input

4: AC main switch

5: Headphone outlet

6: SCART signal input

7: Left video/audio track input

8: AV1 signal input

9: Right video/audio track input

10: S-Video signal input

11: TV signal input

20” LCD TV No Brand N20S651

2.3 OSD Operations

1. Press the MENU button to display or close main menu.

2. Use the cursor up/down to select a menu item.

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

4. Press the MENU button to exit the menu.

Main Menu

Press the MENU button to enter the main OSD (On Screen Display). Adjust the items including Picture Setup, Sound setup, Function Setup and TV setup. When the input source is PC/AV1/AV2 (SCART)/S-VIDEO mode, only the Sound Setup, Picture Setup and Function Setup can be selected; shown in the figure below:

When the input source is TV mode, the Sound Setup, Picture Setup, Channel select Setup, Setup can be selected; shown in

the figure below:

Function Setup and TV

Sound Setup (Same as in PC, TV, AV1, S-Video and AV2(SCART))

1. The range of adjusting volume, bass and treble is from 0~100.

2. Select “ON” or “OFF” in sound selection to control the sound output.

3. Bass and Treble: the easy Equalizer function, Bass can adjust the low frequency sound and Treble can adjust the high frequency sound.

4. The range of adjusting Balance is -50~+50; when adjusting from 0 to -50, the sound from the left track fades until silence; when adjusting from 0 to +50, the sound from the right track fades until silence.

5. AVL: you can set it “ON” or “OFF”.

The function is to adjust the input sound automatically. You may enable this function when you notice that the sound in the two tracks are very different, in order to prevent the bad sound effect resulting from large sound variation.

6. Select "ON" or "OFF" for Loudness: a default setting is preset, you may adjust when necessary.

The following menu will appear when selecting continuously:

20” LCD TV No Brand N20S651

7. Preset: Designed for different types of sound output, wherein, the voice music personal and theater modes are preset; you can set Bass, Treble and Equalizer in sound output mode according to your preference.

8. Equalizer: You can select and adjust 100, 300, 1K, 3K and 8K respectively (the figures represent the sound frequency range).

9. Reset to default: Reset the sound setting to the factory default value.

Picture Setting

When the input source is in PC mode, you can select Brightness, Contrast, Position, Video noise, Sharpness, Auto Adjust, Info, Color Temp., Red, Green, Blue and Reset to default; shown in the figure below:

1. Brightness and Contrast: The range can be adjusted from 0~100.

2. Position: There are two options, Horizontal and Vertical, which can be adjusted from -50 to +50.

3. Video noise: There are two options, Phase and Clock, which can be adjusted from -50 to +50.

4. Sharpness: Select from five options of Softest, Soft, Auto, Sharp and Sharpest. You may adjust the above options according to your preference.

5. Auto Adjust: Automatically adjust PC input to the optimal screen size.

6. Info: Prompt the current size for PC input definition (only the definition that can be shown by this device).

7. Color Temp.: There are four options of color temperature provided for users - normal, warm, cold and Personal. You can select the three color temperatures of normal, warm, and cold, or manually adjust red, green or blue in the personal setting (you can only adjust red, green and blue in the user setting).

8. Reset to default: It is used to reset the picture settings to the factory default mode.

When the input source is in TV/AV1/S-Video/ AV2(SCART), you can select Brightness, Contrast, Colour, Sharpness, Dyn. skin tone, White Tone, preset and Reset to default respectively; shown in the figure below:

20” LCD TV No Brand N20S651

Function Setup

When the input source is in TV, AV1，AV2 or S-Video mode, you can select Source OSD, Language, Country, ACI Timers，Teletext lang./ Teletext E/W and Reset to default; shown in the figure below:

1. Current Source OSD setting: When OSD is set to ON, the left upper corner of the display will show the input source or the TV channel number; when OSD is set to OFF, the input source or the TV channel number will disappear.

2. OSD language setting: There are ten language options provided - English, France, Deutsch, Spanish, Portugese, Polish, Russian, Italian, Finnish, Swedish.

3. Timers

(1).Sleep Timer: Set the sleeping timer and the alert function which indicates the time left. (2). Reminder timer: set the Reminder timer function which give the user a warning

4. Teletext lang. and Teletext E/W：the user can set the teletext language

5. Reset: It is used to reset the OSD settings.

When the input source is in PC mode, you can select Source OSD, Language, Timers and Reset to default; shown in the figure below:

Source OSD, Language, Timers and Reset to default options are operated similarly as the above instructions! When the input source is in TV mode, you can select the difference function.

20” LCD TV No Brand N20S651

Country and ACI function：the user can select Country and if the program system has ACI （Auto Channel Installation）function

TV Setting

The following menu appears only in the TV mode. A. channel select function This set can give the user a channel list that all channel received

B. channel setup function

1. Program nr: Shows the current program number.

2. Program name：show the program name, also the user can give the program a unique name

3. Colour System / sound system: select the colour and sound system the current channel.you can selet ”auto”,the set will identify it by oneself

4. Auto search: Select "Auto Search" to search all signaled channel; when the searching is complete, it stays at the first channel with signal and all channels that have been located are stored. If you would like to stop "Auto Search" during the process, simply by pressing the function button.

5. Frequency：show the current signal Frequency

6. AFC can be set to ON or OFF. When it is set to ON, the TV will search the TV signal automatically; when there is any offset in the signal, it will automatically adjust the channel to the correct position.

7. Reset to default: Reset to the factory default value.

20” LCD TV No Brand N20S651

2.4 How To Connect

VIDEO RECORDER

1. Connect the antenna cable to the RF IN port of your VCR.

2. Connect another FR cable from the port of your VCR to the antenna port of you TV set. If you have connected

the video/audio cable to the video AV port, you may have better sound and picture when playing the VCR .

If your VCR has an S-VHS video jack:

For improved picture quality, connect a S-Video cable with the S-VIDEO input on the TV. S-Video does not provide audio, audio cables must still be connected to provide sound(AV and S terminal share one audio input).

Watching VCR

1. If you use connection TV, select the TV channel auto search.

2. If you use connection AV, select video AV input.

3. Insert videotape in the VCR and press the PLAY button.

How to connect

1. The SCART socket can be connected a VCR, a camcorder, a DVD player, a satellite receiver, a decoder or a

game console form SCART cable.

2. The 21pin SCART socket can also be used as an output to Audio/Video equipment.

How to use

Scart source has the first priority. For example: when playing under other sources such as TV/AV/S-VIDEO/PC, if we input the scart signal, the TV will switch to Scart menu automatically.

How to connect

1. Connect the camera, camcorder and game set to the ports of the audio/video set.

2. The camcorder may get better picture by connecting a S-VHS cable between the S terminal and the Audio set.

How to use it

1. Select the video AV or S terminal input.

2. Enable the exterior AV equipment.

Warning: In case you notice scrolling images, wrong colors or no color, no picture or even combinations of these, on your screen, check if the connections are done in the right way. Check if the cable colors match with the Input connector colors.

20” LCD TV No Brand N20S651

WALL MOUNT

Use of Wall Mount Bracket:

1. Remove the hinger cover.

2. Remove the four units M4.0 screws.

3. Remove the base ass’y.

4. Fasten four units M4.0 X 10mm screws to secure the wall mount bracket.

1. The headphone jack is located at the side of the TV.

2. The MUTE key on the remote control works on both internal speaker and the headphone.

3. Use volume key to adjust the volume.

Care of the screen

Do not rub or strike the screen with anything hard as this may scratch, mar, or damage the screen permanently. Unplug the power socket before cleaning the screen. Dust the TV by wiping the screen and the cabinet with a soft, clean cloth. If the screen requires additional cleaning, use a clean, damp cloth. Do not use liquid cleaners or aerosol cleaners.

Mobile telephone warning

To avoid disturbances in picture and sound, malfunctioning of your TV or even damage to the TV, keep away your mobile telephone from the TV.

End of life directives

We are paying a lot of attention to produce environmentally friendly in green focal areas. Your new receiver contains materials which can be recycled and reused. At the end of its life specialized companies can dismantle the discarded receiver to concentrate the reusable materials and to minimize the amount of materials to be disposed of. Please ensure you dispose of your old receiver according to local regulations.

20” LCD TV No Brand N20S651

3. Input/Output Specification

3.1 Input Signal connector

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

Connect the 15-pin D-SUB 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:

15 - Pin Color Display Signal Cable

11 15

Pin Signal Assignment Pin Signal Assignment

1 Red Video 9 No Pin!

2 Green Video 10 Sync. Ground

3 Blue Video 11 Not Used

4 Not Used 12 Serial Data for DDC

5 GROUND 13 Horizontal Sync.

6 Red Video Ground 14 Vertical Sync.

7 Green Video Ground 15 Serial Clock for DDC

8 Blue Video Ground

20” LCD TV No Brand N20S651

3.2 Factory Preset Display Modes

Analog RGB input signal timing

Timing Resolution

T115 640*480 31k/70Hz can show this timing, but it is out of range actually

T116 640*480 31K/60Hz can show this timing.

T117 640*480 37K/75Hz Can not display this timing, show “out of range”

T118 640*480 37K/72Hz can show this timing, but it is out of range actually

T119 640*480 43K/85Hz Can not display this timing, show “out of range”

T126 800*600 37.8K/60Hz can show this timing, but it is out of range actually

T127 800*600 46K/75Hz Can not display this timing, show “out of range”

H/V

frequency

Remark

T128 800*600 48K/72Hz can show this timing, but it is out of range actually

T129 800*600 53K/85Hz Can not display this timing, show “out of range”

T137 1024*768 48K/60Hz can show this timing, but it is out of range actually

T138 1024*768 56K/70Hz can show this timing, but it is out of range actually

T139 1024*768 60K/75Hz Can not display this timing, show “out of range”

T140 1024*768 69K/85Hz Can not display this timing, show “out of range”

T144 1280*1024 63K/60Hz can show this timing, but it is out of range actually

T148 1280*1024 80K/75Hz Can not display this timing, show “out of range”

20” LCD TV No Brand N20S651

4. Mechanical Instructions

Step Figure

Description

Preparation and remove the base

Remove the screws remarked in red

Remove back cover

Remove the screws remarked in red

20” LCD TV No Brand N20S651

Remove shield

Remove the screws remarked in red

20” LCD TV No Brand N20S651

Remove the boards and main frame

Remove connectors and the screws remarked in red

20” LCD TV No Brand N20S651

Remove the panel

The end

Remove the screws remarked in red

20” LCD TV No Brand N20S651

5. Repair Flow Chart

5.1. No Display (LED indicator green)

Check I2C communication

No display

Check the source

Check LVDS cable

Check 12V power supply

Check main board power supply

Check U406

Check panel

Reset source

Replace LVDS cable

Return to “5.3”

Replace U406

Repair I2C communication relative circuit

Replace panel

20” LCD TV No Brand N20S651

5.2. Can’t start (LED indicator yellow)

Can’t start

Check keyboard

Repair the keyboard

Check 5V_SB

Check every chip power supply

Check I2C communication

Replace I2C communication component

Check oscillistor

Replace oscillistor

20” LCD TV No Brand N20S651

5.3. No Power (No LED indicator)

Check IC901, Q901

No Power

Check power cord and board interface

Check F901, BD901

Plug in power cord and interface

Replace F901 or BD901

Check the load

Replace IC901 or Q901

Check T901

Replace T901

Check D904, D905

Replace D904, D905

Check Q903, ZD902, IC903，IC902 and relative circuit

Check Q906, IC905 and relative circuit

Replace Q903, ZD902, IC903 IC902

20” LCD TV No Brand N20S651

5.4. Abnormal Display

Abnormal display

Check the source

Reset source

Check signal filter circuit

Replace the filter or inductance

AV, S-video signal component PC signal

Check input signal

RF signal

Check TV system setup

Repair each relative circuit

Check LVDS cable

Check panel

Replace LVDS cable

Replace panel

Check TU601

Replace TU601

20” LCD TV No Brand N20S651

5.5. No Sound

No sound

Check the source

Reset source

Check signal filter circuit

Replace the filter or inductance

Check Earphone jack

Replace the Earphone jack

SIF signal

Check TV system setup

Check Amplifier TDA7266D U601

Check speakers

AV, component, S-video, PC signal

Replace speakers

Replace U601

Check TU601

Check relative circuit

Replace TU601

+ 55 hidden pages