AOC LM721A User manual

LM721A Service Manual Rev: A
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17” LCD Monitor
LM721A
THESE DOCUMENTS ARE FOR REPAIR SERVICE INFORMATION ONLY. EVERY REASONABLE
EFFORT HAS BEEN MADE TO ENSURE THE ACCURACY OF THIS MANUAL; WE CANNOT GUARANTEE
THE ACCURACY OF THIS INFORMATION AFTER THE DATE OF PUBLICATION AND DISCLAIMS RE
LIABILITY FOR CHANGES, ERRORS OR OMISSIONS.
Prepared: LiuYongFeng
Date: May-16-04
SERVICE MANUAL

LM721A Service Manual Rev: A
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Revision History
Revision Date Page Items Modification
A May-16-04 All First version release;

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TABLE OF CONTENTS
TABLE OF CONTENTS---------------------------------------------------------------------------------------------------3
1.MONITOR SPECIFICATIONS---------------------------------------------------------------------------------5
2. LCD MONITOR DESCRIPTION -------------------------------------------------------------------------------6
3. OPERATING INSTRUCTIONS -------------------------------------------------------------------------------7
3.1 GENERAL INSTRUCTIONS ---------------------------------------------------------------------------------------7
3. CONTROL BUTTONS -------------------------------------------------------------------------------------------7
3.3 ADJUSTING THE PICTURE-------------------------------------------------------------------------------------7
4. INPUT/OUTPUT SPECIFICATION-----------------------------------------------------------------------------9
4.1 INPUT SIGNAL CONNECTOR ------------------------------------------------------------------------------9
4.2 FACTORY PRESET DISPLAY MODES -------------------------------------------------------------------- 10
4. POWER SUPPLY REQUIREMENTS ------------------------------------------------------------------------ 11
4.4 PANEL SPECIFICATION (QDI EL07) --------------------------------------------------------------------12
5. BLOCK DIAGRAM ---------------------------------------------------------------------------------------------------14
5.1 MONITOR EXPLODED VIEW --------------------------------------------------------------------------14
5.2 SOFTWARE FLOW CHART-------------------------------------------------------------------------------15
5.3 ELECTRICAL BLOCK DIAGRAM -----------------------------------------------------------------------17
6. SCHEMATIC -------------------------------------------------------------------------------------------------------20
6.1 MAIN BOARD------------------------------------------------------------------------------------------------------20
6.2 INVERTER/POWER BOARD-----------------------------------------------------------------------------23
6.3 KEY BOARD -----------------------------------------------------------------------------------------------26
7. PCB LAYOUT -------------------------------------------------------------------------------------------------27
7.1 MAIN BOARD--------------------------------------------------------------------------------------------------------27
7.2 INVERTER/POWER BOARD------------------------------------------------------------------------------------29

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7.3 KEYPAD BOARD AND AUDIO BOARD---------------------------------------------------------------------31
8. MAINTAINABILITY --------------------------------------------------------------------------------------------------32
8.1 EQUIPMENTS AND TOOLS REQUIREMENTS ----------------------------------------------------32
8.2 TROUBLE SHOOTING -----------------------------------------------------------------------------------33
9. WHITE-BALANCE, LUMINANCE ADJUSTMENT -------------------------------------------------39
10. BOM LIST --------------------------------------------------------------------------------------------------------40

LM721A Service Manual Rev: A
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1. Monitor Specifications
Driving system TFT Color LCD
LCD Panel Size 43.2cm(17.0")
Pixel pitch 0.264mm( H )x 0.264mm( V )
Viewable angle 150˚(H) 110˚(V)
Response time (typ.) 16 ms
Video Analog /Digital
Input Sync. Type H/V TTL
H-Frequency 30kHz – 80kHz
V-Frequency 55-75Hz
Display Colors Over 16 million Colors
Dot Clock 135MHz
Max. Resolution 1280 x 1024
Plug & Play VESA DDC2BTM
Power Consumption ON Mode <45W
OFF Mode
<3W
Maximum Screen
Size
Horizontal : 13.3”(337.92mm)
Vertical : 10.6”(270.336mm)
Power Source 100~240VAC,47~63Hz
Environmental
Considerations
Operating Temp: 0°C to 40°C
Storage Temp.: -20°C to 60°C
Operating Humidity : 15% to 90%
Weight (N. W.) Packaged 7.0Kg Unit
Unpackaged 5.0Kg Unit

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2. Lcd Monitor Description
The LCD MONITOR will contain a main board, an inverter/power board, keypad board , Audio board
and external power adapter which house the flat panel control logic, brightness control logic and
DDC.
The Inverter board will drive the backlight of panel and the DC-DC conversion.
The Adapter will provide the 12V DC-power to inverter/power board.
Inverter/Power board
Flat Panel and
CCFL backlight
Main Board
Keyboard
RS232 Connector
For white balance
adjustment in
factory mode
HOST Computer
CCFT Drive.
DC-IN 12V
Video signal, DDC
Monitor Block Diagram

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3. Operating Instructions
3.1 General Instructions
Press the power button to turn the monitor on or off. The other control buttons are located at front panel of the monitor. By
changing these settings, the picture can be adjusted to your personal preferences.
-The power cord should be connected.
-Connect the video cable from the monitor to the video card.
-Press the power button to turn on the monitor, the power indicator will light up.
3.2. Control Buttons
-Power Button:
When pressed, the monitor enters the off mode, and the LED turns blank. Press again to restore normal status.
-Left / Right Button:
When the OSD show on screen, Left/Right Button are used to control the monitor functions. Press to switch functions or adjust
settings. And if the OSD off, Left/Right buttons are used to control the audio volume;
-Auto Adjust Key:
The Auto Adjust Key is used to automatically set the H Position, V Position, Clock and Phase.
-Power Indicator:
Green — Power On mode.
Orange — Power Saving mode.
Blank —Power Off Mode.
A B C D E F
Menu Volume Auto LED Power
A. Menu button
B. Left button/Volume down
C. Right button/Volume up
D. Auto button/Exit
E. Indicator light
F. Power button
3.3 Adjusting the Picture
CONTROL Buttons

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OSD Table:
1.
Contrast Adjust the picture contrast.
2. Brightness Adjust the picture brightness.
3. Focus Adjust picture Focus.
4. Clock Adjust picture Clock.
5.
H_Position Adjust the horizontal position of the picture.
6. V.Position Adjust the vertical position of the picture.
7. Input Selected
Input Signal source sleeted (select Analog or Digital input
source).
8. Language Multi-Language selection
9. Dos-mode selected
Dos-mode resolution selection for 720x400 @70Hz and
640x400 @70Hz
10. Red Adjusts Red intensity.
11. Green Adjusts Green intensity.
12. Blue Adjusts Blue intensity.
13. C1 (Warm) Color Set the color temperature to warm white.
14. C2 (Cool) Color Set the color temperature to cool white.
15.
Reset
Clear each old status of Auto-configuration and re-do
auto-configuration .
16. Exit Save user adjustment and OSD disappear.

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4. Input/Output Specification
4.1 Input Signal Connector
PIN NO. DESCRIPTION
PI N NO.
DESCRIPTION
1. Red 9. +5V
2. Green 10. Detect Cable
3. Blue 11. NC
4. Ground 12. DDC-Serial Data
5. Ground 13. H-Sync
6. R-Ground 14. V-Sync
7. G-Ground 15. DDC-Serial Clock
8. B-Ground
VGA connector layout
15
610
11 15

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4.2 Factory Preset Display Modes
VESA MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
+/- 0.5kHz
Sync
Polarity
Nominal
Freq.
+/- 1 Hz
Sync
Polarity
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 37.500 N 75.00 N 31.500
800x600@56Hz 1024 x 625 35.156 N/P 56.250 N/P 36.000
800x600@60Hz 1056 x 628 37.879 P 60.317 P 40.000
800x600@72Hz 1040 x 666 48.077 P 72.188 P 50.000
SVGA
800x600@75Hz 1056x625 46.875 P 75.000 P 49.500
1024x768@60Hz 1344x806 48.363 N 60.004 N 65.000
1024x768@60Hz 1312x813 48.78 N 60.00 N 64.000
1024x768@70Hz 1328x806 56.476 N 70.069 N 75.000
1024x768@72Hz 1304x798 57.515 P 72.074 P 75.000
1024x768@75Hz 1328x804 60.200 N 74.90 N 80.000
XGA
1024x768@75Hz 1312x800 60.023 P 75.029 P 78.750
XGA 1152x864@75Hz 1600x900 67.50 P 75.000 P 108.000
1280x1024@60Hz 1688x1066 63.981 P 60.020 P 108.000
SXGA 1280x1024@75Hz 1688x1066 79.976 P 75.025 P 135.000
IBM MODES
Horizontal Vertical
Mode Resolution Total
Nominal
Frequency
+/- 0.5kHz
Sync
Polarity
Nominal
Freq.
+/- 1 Hz
Sync
Polarity
Nominal
Pixel
Clock
(MHz)
DOS* 720x400@70Hz 900 x 449 31.469 N 70.087 P 28.322
DOS** 640x400@70Hz 800 x 449 31.469 N 70.087 P 25.175
MAC MODES
VGA 640x480@67Hz 864x525 35.000 N 66.667 N 30.240
SVGA 832x624@75Hz 1152x667 49.725 N 74.551 N 57.2832