AOC L27W451B Schematic
27’’ LCD TV Color Monitor AOC L27W451B
Service
Service
Service
31.5KHz-48KHz
Description Page Description Page
Table Of Contents.......……..............................…........1
Revision List.…........................................……......2
1. Monitor Specification..............................………........3
2. Operating Instructions…………………….……….......5
2.1 The Use Of Remote Control..……………...................5
2.2 The Use Of Teletext……..........…...........…...........6
2.3 Front Panel Control Knobs.…............……...............7
2.4 OSD Operations…...……........................…............8
2.5 How To Connect………..............……………............16
3. Input/Output Specification…………..........................20
3.1 Input Signal Connector………….…..........................20
3.2 RGB Input Signal Timing …….....……......................21
4. Mechanical Instructions…………………..................22
5. Repair Flow Chart ……………………….……….....27
6. White Balance Luminance Adjustment….…........33
7. PCB Layout..………….……………………....….......37
7.1 Main Board….…..…........................................37
ANY PERSON ATTEMPTING TO SERVICE THIS CHASSIS MUST FAMILIARIZE HIMSELF WITH THE
TABLE OF CONTENTS
7.2 Power Board.…..……..….…..............................39
7.3 Key Board…...................................... .... ....... ... ...42
7.4 IR Board..…................….......................42
7.5 DC-DC Board....…………...............................44
7.6 Earphone Board..…..….....…..........................45
8. Block Diagram..…….........................................46
8.1 Main Board…………………………………..….46
8.2 Power Board..…..…....………………….......47
8.3 Exploded View....……….....................…..48
9. Schematic Diagram………………………...49
9.1 Main Board………..………………………..49
9.2 Power Board.....…...................................61
9.3 Tuner Board...…….......................................63
9.4 Earphone Board………….………………….66
10. BOM List…......................................................67
11. Different Parts List.…..................…....................94
SAFETY NOTICE
Horizontal Frequency
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
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27’’ LCD TV Color Monitor AOC L27W451B
Revision List
Version Release Date Revision Instructions TPV Model
A00 Oct.-30-2006 Initial Release E275MTNBC3A3NP
A00 Nov.-22-2006 Second Release E275MTNBC3AC2P
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27’’ LCD TV Color Monitor AOC L27W451B
1. Monitor Specifications
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
2. Operations Instructions
2.1 The Use of Remote Control
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27’’ LCD TV Color Monitor AOC L27W451B
2.2 The Use Of Teletext
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27’’ LCD TV Color Monitor AOC L27W451B
2.3 Front Panel Control Knobs
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27’’ LCD TV Color Monitor AOC L27W451B
2.4 OSD Operations
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
2.5 How to Connect
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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27’’ LCD TV Color Monitor AOC L27W451B
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 p ower 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 sy stem device and lock both scre ws on
the connector to ensure firm grounding. The connector information is as follow:
1
6
11 15
5
10
15 - Pin Color Display Signal Cable
Pin No. Description
1 Red Video
2 Green Video
3 Blue Video
4 Not used
5 GROUND
6 Red Video Ground
7 Green Video Ground
8 Blue Video Ground
9 No Pin
10 Sync. Ground
11 Not used
12 Serial Data for DDC
13 Horizontal Sync.
14 Vertical Sync.
15 Serial Clock for DDC
Apply power to the display by turning the power switch to the "ON" position and allow about ten seconds fo r 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.
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27’’ LCD TV Color Monitor AOC L27W451B
3.2 RGB Input Signal Timing
Horizontal Vertical Sync Polarity Presence Screen Mode
Dots × Lines
720×400 31.47 70.08
640×480 31.50 60.00
640×480 37.50 75.00
640×480 37.86 72.81
800×600 37.90 60.32
800×600 46.90 75.00
800×600 48.08 72.19
1024×768 48.40 60.00
1280×768 47.7 60
Frequency Frequency Horizontal Vertical Horizonta Vertical Normal FULL
(kHz) (Hz) (4:3) (16:9)
NEG POS YES YES YES YES
NEG NEG YES YES YES YES
NEG NEG YES YES YES YES
NEG NEG YES YES YES YES
NEG NEG YES YES YES YES
NEG NEG YES YES YES YES
NEG NEG YES YES YES YES
YES YES YES YES YES YES
YES YES YES YES YES YES
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27’’ LCD TV Color Monitor AOC L27W451B
4. Mechanical Instructions
Step Figure Description
Lay the LCD-TV
Preparation
on a flat, soft and
clean surface.
Remove
the base
Remove
the stand
Remove the
hinge cover
Remove the
screws on the
stand to remove
the stand.
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27’’ LCD TV Color Monitor AOC L27W451B
Remove the six
Remove
the back
cover
screws mark in
red to remove the
back cover.
Remove
the shield
1、Remove the
twelve screws
1. Disconnect the
connector
marked in green
and remove
keyboard
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27’’ LCD TV Color Monitor AOC L27W451B
Remove
the shield
Remove
Inverter ,
tuner and
power
board
2.Push the shield
as the arrowhead
direction.
1.Remove the
five screws
marked in red to
remove the
inverter board.
2. Remove the
seven screws
marked in red to
remove the main
board and tuner
board
3.Disconnect the
connector and
remove the tuner
board , power
board and main
board.
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27’’ LCD TV Color Monitor AOC L27W451B
1、remove the
screws and
connector to
remove the ir
board.
Remove
the bezel
Remove
the main
frame
Remove the
fourteen screws
to remove bezel.
1.Remove the
eight screws to
remove main
frame.
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27’’ LCD TV Color Monitor AOC L27W451B
The end
N/A
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27’’ LCD TV Color Monitor AOC L27W451B
5. Repair Flow Chart
5.1 No Power (No LED indicator)
Check power cord and board interface
OK
Check F901, BD901, D901, D902
NG
OK
Check the load
Check IC981, D928 (12V)
NG
OK
Check Q924, IC924 (ON/OFF signal)
OK
Check IC941, Q941
NG
OK
Check T951
NG
OK
Check IC901, Q901
NG
OK
Check Q942, Q943
NG
OK
Check IC927
NG
NG
Replace F901 or BD901 or D910 or D902
Replace IC981or D928
NG
Replace IC941, Q941
Replace T951
Replace IC901 or Q901
Replace Q942 or Q943
Replace IC927
Plug in power cord and interface
Replace Q924 or IC924
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27’’ LCD TV Color Monitor AOC L27W451B
5.2 Can not start (LED indicator yellow)
Check key board
NG
Repair the key board
OK
Check 5V_SB
NG
Return to “5.1”
OK
Check 3.3V_SB
OK
NG
Replace U701
Check Q704, Q705, Q706, Q709
NG
Replace Q704 or Q705
or Q706 or Q709
Check PWR_ON signal
NG
Check U32, U21
NG
Replace U32 or U21
OK
Check I2C communication
Check Panel inverter board
NG
Replace panel
Check PFC circuit
NG
Replace IC901 or Q901
OK
Check main board power supply
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27’’ LCD TV Color Monitor AOC L27W451B
5.3 No display (LED indicator green)
Check the source
NG
Reset source
OK
Check LVDS cable
NG
Reset LVDS cable
OK
Check 24V power supply
NG
Return to “5.1”
OK
Check main board power supply
OK
Check U21
NG
Replace U21
OK
Check I2C communication
OK
Check panel
NG
Replace panel
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