AOC L27W431 User manual

27’’ LCD TV AOC L27W431
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Service
Service
Service
显示桌面.scf
Horizontal Frequency
31.5kHzto49kHz
TABLE OF CONTENTS
Description Page Description Page
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
Table Of Contents.......…….............................…..............1
Revision List………………………………………………....2
Important Safety Notice.......................................……......3
1.General Specification.................................………........4
2.Operating Instructions…………...………….……….......5
2.1.The Use Of Remote Control…….…….…….…….......5
2.2.Front Panel Control Knobs…..…….……….……….....6
2.3.To Use the Menus....…...………………….……….......7
2.4.How To Connect……..…………………….……….....13
3. Input/Output Specification…………....................…....15
4. Mechanical Instructions…………………….................17
5. Repair Flow Chart ……………………….…….…….....19
6.White-Balance, Luminance Adjustment...........25
7.PCB Layout ………….…..………………....….......29
7.1.Main Board………….…..………….……….......29
7.2.Power Board……………..………….……….......32
7.3.Tuner Board…………...……………..……….......34
8.Block Diagram…….….……………………………..36
9. Schematic………………………………………...37
9.1.Main Board…………...……………………….......37
9.2.Power Board………………………….…………...48
9.3.Tuner Board…………………………….…….......50
10.Exploded View..………………............................54
11.BOM List…………..……….……………………….55

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Revision List
Version Release Date Revision History TPV Model
A00 Apr.-05-2007 Initial Release E276MTNSD1A4NP

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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.)

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1. General Specification
Items Specification
Screen Size 27” TFT-LCD Panel
Panel type TV 27" B1-L03 CMO
Aspect Ratio 16:9
Resolution (Native) 1366 x 768 WXGA
Active Area 603.22 (H) x 341.98 (V) mm
Pixel Pitch 0.1455 (H) x 0.4365 (V) mm
Contrast Ratio 1200:1 (Typical)
Brightness 500 nits (Typical)
Response Time 6.5ms (G-G)
Display colors 16.7 million
Rated Life (Backlight) > 60000 Hrs (at 4.5mA)
LCD Panel
Preset Color Cool /warm
TV Tuning System NTSC 181 channel (PLL band) electronic adjustment
system
Sound System MTS + SAP
TV Function
Color systems NTSC / PALN / PALM
AV1 RCA x 1 Audio channel L / Rx 1
AV2 RCA x 1
S-Video x 1
Audio channel
L / R x 1（shared）
S-VIDEO S-VIDEO x 1 Audio channel L / Rx 1
HDMI HDMI x 1 High Definition Media
Interface
Video Input
COMPONENT
(480i/480p/720p/1080i) Y,Pb,Pr x 1 Audio channel L / Rx 1
Signal Input Analog: D-Sub 15 pin (detachable cable)
PnP compatibility DDC 2B
Input frequency Analog: FH: 31.5kHz to 49kHz
FV: 56Hz to 75Hz
Recommended Analog:1024 x 768 (60Hz)
PC Input
Input Audio Headphone Mini-jack for stereo (3.5ø)
Speaker (built-in): Two 15W speakers
Headphone Mini-jack for stereo (3.5ø)
Audio Output Audio Output: L / R
Line Output (RCA L/R)
OSD language English / Spanish / Portuguese
Wall Mount VESA 100mm X 100mm
Power Input AC100V~240V, 50/60Hz
Power Power
Consumption <200W
Operating Temperature + 0 °C ~ + 40 °C
Operating Humidity 10% to 85%
Environment
Storage Temperature - 10 °C ~ + 60 °C
Accessories Remote Controller, Batteries (x2), AC Power Cord, D-sub Signal Cable, Audio
Cable ,User’s Manual

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2. Operations Instructions
2.1 The Use of Remote Control

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2.2 Front Panel Control Knobs
: Press to turn the TV on or off.
MENU Key: Press to show the OSD menu and exit OSD menu at the TV.
Down / Up Key: Press to select OSD function or change channel.
- / + Key: Press to confirm your function selection and make adjustment.
Source Key: Press to select your input source.

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2.3 To Use the Menus
1. Press the MENU button to display each 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
SOURCE SELECT
Press the INPUT key on remote control or SOURCE key on keyboard to select source:
TV>AV1>AV2>S-VIDEO>COMPONENT>VGA>HDMI
Menu screen in TV mode:
Press the MENU button to enter into the OSD MENU in TV mode. Items adjustable include: VIDEO SETTING,
SOUND SETTING, OPTIONS SETTING, and CHANNEL SETTING
VIDEO SETTING:
1. PICTURE: User can select PERSONAL,VIVID,STANDARD,MILD,if selected except PERSONAL
item, Contrast, Brightness ,Saturation,Sharpness,NR,Backlight can’t adjust.
2. CONTRAST: Adjust black and white level, suitable contrast can make picture more lightly. Adjustment range is
from 0 to 100.
3. BRIGHTNESS: Adjust background brightness, user can collocation it with contrast adjustment range is from 0 to
100.
When adjust any item sub-OSD will show up like this.
4. SATURATION: Adjust color saturation, range is from 0 to 100.

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5. SHARPNESS: Adjustment picture sharpness, range is from 0 to 100.
6. NR: When the signal is poor, you can turn on the noise reduction function.
7. BACKLIGHT: The adjustment range of Black Level is from 0 to 10.
You can adjust contrast, brightness, Saturation, Sharpness to your prefer level.
SOUND SETTING
1. VOLUME: The Volume adjustment range is from 0 to 100
You can adjust the Volume of the picture to the level you prefer.
2.EFFECT：You can choice your prefer mode of CUSTOM, STEREO, NEWS, MOVIE, MUSIC, BBE VIVA.
3.120Hz, 500Hz, 1500Hz, 5 KHz, 10KHZ. Choice the prefer frequency to increase or decrease.
OPTIONS SETTING:
English
1. MENU LANGUAGE: This indicates the different languages available for the OSD menu, including English, panish
and Portuguese. The default is English.
2. MENU TIMEOUT: OSD stay timer.
3. MENU BACKGROUND: User can select Opaque or transparency with Menu background.
4. SLEEP TIMER: Use this button to set a time period after which the TV will enter into standby mode. The time
period can be 0>15>30>45 > 60 > 90 >120 minutes. The timer will begin to count down from the selected number of
minutes after the OSD menu disappears.
Note: To check the remaining time, press the SLEEP button. To cancel the sleep timing, press the SLEEP button
repeatedly until 0 appears. If you turn off the TV after you set the sleep timing, the setting will be cleared. You will

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need to set it again.
5. BLUE SCREEN: When there is no signal input in TV, AV, S-Video and HDTV modes, the screen will become blue.
If set to on, the screen will become blue. If set to Off, the screen will display a snowy picture when in TV signal mode
and become black in other signal modes. The default is On.
6. CC: You can enter to select the closed caption function.
7. RESET: Used to resume the TV’s default settings.
CHANNEL SETTING:
1. AIR/CABLE: You can select the TV signal AIR or CABLE.
2. AUTO SEARCH: Used to scan all the TV channels and save to memory.The TV’s total number of channels is 125
(1-125). If you use the remote control to select a number out of the range of 1-125, it will automatically skip to the
channel number you previously watched.
Menu screen in VGA mode:
The TV has a VGA analog interface, which can be switched using the INPUT button on the remote control.

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Press the MENU button to enter into the OSD Main Menu. Adjustable items include: VIDEO SETTING, SOUND
SETTING, OPTIONS SETTING, VGA SETTING
VIDEO SETTING:
1. CONTRAST: Adjust black and white level, suitable contrast can make picture more lightly. Adjustment range is
from 0 to 100.
2. BRIGHTNESS: Adjust background brightness, user can collocation it with contrast adjustment range is from 0 to
100.
SOUND SETTING:
1. VOLUME: The Volume adjustment range is from 0 to 100
You can adjust the Volume of the picture to the level you prefer.
2.EFFECT：You can choice your prefer mode of CUSTOM, STEREO, NEWS, MOVIE, MUSIC, BBE VIVA.
3.120Hz, 500Hz, 1500Hz, 5 KHz, 10KHZ. Choice the prefer frequency to increase or decrease.
OPTIONS SETTING:

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1. MENU LANGUAGE: This indicates the different languages available for the OSD menu, including Simplified
English, Spanish and Portuguese. The default is English.
2. MENU TIMEOUT: OSD stay timer.
3. MENU BACKGROUND: User can select Opaque or transparency with Menu background.
4. SLEEP TIMER: Use this button to set a time period after which the TV will enter into standby mode. The time
period can be 0>15>30>45 > 60 > 90 > 120 minutes. The timer will begin to count down from the selected number of
minutes after the OSD menu disappears.
Note: To check the remaining time, press the SLEEP button. To cancel the sleep timing, press the SLEEP button
repeatedly until 0 appears. If you turn off the TV after you set the sleep timing, the setting will be cleared. You will
need to set it again.
5. BLUE SCREEN: When there is no signal input in TV, AV, S-Video and HDTV modes, the screen will become blue.
If set to on, the screen will become blue. If set to off, the screen will display a snowy picture when in TV signal mode
and become black in other signal modes. The default is On.
6. RESET: Used to resume the TV’s default settings.
VGA SETTING:
1. Horizontal Position: change horizontal position on screen.
2. Vertical position: change vertical position on screen.
3. Clock: (The function only in VGA mode)
4. Focus: Adjust A/D focus. (The function only in VGA mode)
5. Auto tune: Auto tune to a best status on screen.(The function only in VGA mode)
6. Color temp: According your preference to adjust color temperate, there are warm, cool, standard.
7. Reset: recall defaulting.
Menu screen in AV1/AV2/S-VIDEO/COMPONET/HDMI mode:

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Press the MENU button to enter into the OSD MENU in AV1/AV2/SVIDEO/COMPONET/HDMI mode. Items
adjustable include: VIDEO SETTING, SOUND SETTING, OPTIONS SETTING，VIDEO SETTING:
Adjusting is same as the VIDEO SETTING in TV mode.
SOUND SETTING:
Adjusting is same as the SOUND SETTING in TV mode.
OPTION SETTING:
Adjusting is same as the OPTIONS SETTING in TV mode.

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2.4 How to Connect
VIDEO RECORDER
1. Connect the antenna or cable 1 to the RF IN port of your VCR.
2. Connect another RF cable 2 from the output RF of your VCR to the Antenna input of your TV. Better quality when
playing from our VCR can be obtained if you also connect the Video, Audio LEFT AND right (only for stereo
equipment) cables 3 to the VIDEO, AUDIO L and R inputs AV. If you are using mono equipment, connect only the
VIDEO and the AUDIO L (Mono) ports.
If you’re VCR has an S-VHS video jack:
For improved picture quality, connect a S-Video cable with the S-VIDEO input on the TV instead of connecting the
VCR to the VIDEO port of AV2. S-Video does not provide audio, audio cables must still be connected to
provide sound. (S-Video and AV2 has the same audio input port)
CAMERA，CAMCORDER，VIDEO GAME SET，…..
1. Composite Video: Connect your camera, camcorder, videogame set… to Audio port 2 (Audio L for mono) and
Video port 3.
2. S-Video Connection
S-VHS quality with an S-VHS camcorder is obtained by connecting the S-VHS cable with the S-VIDEO input 1 and
AUDIO input 2.
DVD PLAYER
1. Connect the three separate component video cables 1 to the DVD player’s, Pb and Pr ports and to the Y, Pb and
Pr ports on the TV

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2. Connect the audio cables 2 to the DVD player’s AUDIO L and R ports and to the L and R AUDIO AV ports on the
TV.
HDMI:
HDMI is the leading new standard for Digital video and audio interconnection.
To the HDMI connector you can connect HDMI devices such as a Set Top Box or compatible DVD-R or DVD player
with HDMI export, or DVI-equipped devices like a computer. So you can display high definition pictures on this TV in
the digital form.
DIGITAL SET TOP BOX
1. Connect the three separate component video cables 1 to the DTV set-top box Y, Pb and Pr ports and to the Y, Pb
and Pr ports on the TV.
2. Connect the audio cables 2 to the DTV player’s AUDIO L and R ports and to the L and R AUDIO AV ports on the
TV.
HEADPHONE
1. The earphone jack is located at the rear corner of the TV.
2. The MUTE key on the remote control works on both internal speaker and the earphone.
3. Use volume key to adjust the volume.
Note: When a TV channel or external AV source is blocked because of a rating set via the Parental (V-Chip) control
menu, the headphone will also be muted.

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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
Pin Signal Assignment Pin Signal Assignment
1 Red Video 9 No Pin!
2 Green Video 10 Sync. Ground
3 Blue Video 11 SDA (Remote Control)
4 SCL (Remote Control) 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
HDMI Digital connector pin assignments
Pin Signal Assignment Pin Signal Assignment
1 TMDS Data2+ 2 TMDS Data2 Shield
3 TMDS Data2- 4 TMDS Data1+
5 TMDS Data1 Shield 6 TMDS Data1-
7 TMDS Data0+ 8 TMDS Data0 Shield
9 TMDS Data0- 10 TMDS Clock+
11 TMDS Clock Shield 12 TMDS Clock-
13 CEC 14 NC
15 SCL 16 SDA
17 DDC/CEC Ground 18 +5V Power
19 Hot Plug Detect

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Apply power to the display by turning the power switch to the "ON" position and allow about ten seconds for
Panel warm-up. The Power-On indicator lights "GREEN" when the display is on.
With proper signals feed to the display, a pattern or data should appear on the screen, adjust the brightness and
contrast to the most pleasing display, or press auto-adjust to get the best picture-quality.
This TV (with PC function) has power saving function following the VESA DPMS. Be sure to connect the signal
cable to the PC.
If your TV requires service, it must be returned with the power cord.
3.2 Factory Preset Display Modes:
Analog RGB input signal timing
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
(KHz)
Sync
Polarity
Nominal
Freq.
(Hz)
Sync
Polarit
y
Nominal
Pixel
Clock
(MHz)
640x480@60Hz 800 x 525 31.469 N 59.940 N 25.175
640x480@72Hz 832 x 520 37.861 N 72.809 N 31.500
VGA
640x480@75Hz 840 x 500 37.5 N 75 N 31.500
800x600@56Hz 1024 x 625 35.156 P 56.25 P 36.000
800x600@60Hz 1056 x 628 37.879 P 60.317 P 40.000
800x600@72Hz 1040 x 666 48.097 P 72.188 P 40.000
SVGA
800x600@75Hz 1056 x 625 46.0875 P 75 P 49.5
1024x768@60Hz 1344x806 48.363 N 60.004 N 65.000
1024x768@70Hz 1328x806 56.476 N 70.069 N 75.000
XGA
1024x768@75Hz 1312x800 60.023 P 75.029 P 78.750
WXGA 1360x768@60Hz 1792x795 47.712 P 60.015 P 85.5
HDMI input signal timing
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
(KHz)
Sync
Polarity
Nominal
Freq.
(Hz)
Sync
Polarity
Nominal
Pixel
Clock
(MHz)
720P 1280×720P 45.00 60 74.25
1080i 1920X1080i 33.75 60 74.25
480P 720X480P 31.54 60 27.00

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4. Mechanical Instructions
Step Figure Description
Preparation
Lay the LCD-TV on a
flat, soft and clean
surface. Disassemble
the stand cover.
Remove
the stand
Remove the 4 screws
remove
the rear
cover
Remove the 14 screws
to remove the rear
cover
Remove
the shield
Remove the 6 screws

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Remove
the shield
Remove the 8 screws
Remove
the main
board &
power
board
Remove the 9 screws
& 6 connectors to
remove the main
board and power
board.
Remove the 1 screwa
and 3 connectors .
Remove
the bezel
Remove the 14 screws
around the main
frame.

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5. Repair Flow Chart
5.1 No Power (No LED indicator)
Check power cord and board interface Plug in power cord and interface
OK
Check F901, BD901, D901, D902 NG Replace F901 or BD901 or D910 or D902
OK
Check IC981, D928 (12V)
Check Q941
NG Replace IC981or D928
Check IC901
NG
Replace IC901
OK
OK
Check IC941
OK
NG
Replace IC941
Replace Q941
OK
Check Q946 Q947
Check Q901 Replace Q901
OK
NG
NG
NG Replace Q946 Q947
Check IC927
Check the load
OK
Replace IC927
NG
NG

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5.2 Can not start (LED indicator yellow)
NG
OK
Check 5V_SB
NG Return to “5.1”
OK
Check PWR_ON signal Check main board power supply and U402
NG
Check I
2
C communication
OK
Check key board
Check Panel inverter board NG Replace panel
Repair the key board
OK