How it Works
AOC
Loading...
LM923
Schematic
55 pgs3.68 Mb0
User Manual
20 pgs258.99 Kb0

AOC LM923 Schematic

AOC LM923
Page 1 of 55
SERVICE MANUAL
19” LCD MONITOR
LM923
THESE DOCUMENTS ARE FOR REPAIR SERVICE INFORMATION ONLY. EVERY REASONABLE EFFORT HAS
THIS INFORMATION AFTER THE DATE OF PUBLICATION AND DISCLAIMS RELIABILITY FOR CHANGES,
ERRORS OR OMISSIONS.
http://www.wjel.net
AOC LM923
Page 2 of 55
Table of Content
Revision List…………………………………………………………………………………………………………. 3
1. Monitor Specifications………………………………………………………………………………………….. 4
2. LCD Monitor Description……………………………………………………………………………………….. 5
3. Operating Instructions………………………………………………………………………………………….. 6
3.1 General Instructions…………………………………………………………………………………………... 6
3.2 Control Buttons………………………………………………………………………………………………... 6
3.3 Adjusting the Picture………………………………………………………………………………………….. 7
4. Input/Output Specification……………………………………………………………………………………... 9
4.1 Input Signal Connector……………………………………………………………………………………….. 9
4.2 Factory Preset Display Modes……………………………………………………………………………….. 10
4.3 Power Supply Requirements………………………………………………………………………………… 10
4.4 Panel Specification………………………………………………………………………………………….… 11
4.4.1Display Characteristics………………………………………………………………………………… 11
4.4.2Optical Characteristics…………………………………………………………………………………… 11
4.4.3 Parameter Guide Line For CCFL Inverter……………………………………………………………… 12
5. Block Diagram………………………………………………………………………………………………….… 13
5.1 Monitor Exploded View……………………………………………………………………………………….. 13
5.2 Software Flow Chart…………………………………………………………………………………………... 14
5.3 Electrical Block Diagram……………………………………………………………………………………… 16
5.3.1 Main Board………………………………………………………………………………………………... 16
5.3.2 Inverter/Power Board………………………………………………………….…………………………. 17
6. Schematic……………………………………………………………………………………………………….… 18
6.1 Main Board…………………………………………………………………………………………………….. 18
6.2 Audio Board……………………………………………………………………….………………………….. 24
6.3 Power Board……………………………………………………………………….………………………….. 25
7. PCB Layout………………………………………………………………………………………………………. 28
7.1 Main Board…………………………………………………………………………………………………….. 28
7.2 Audio Board…………………………………………………………….……………………………………… 29
7.3 Power Board………………………………………………………………………….……………………….. 30
7.4 Key Board……………………………………………………………………………………………………… 30
8. Maintainability……………………………………………………………………………………………………. 31
8.1 Equipments and Tools Requirement………………………………………………………………………… 31
8.2 Trouble Shooting…………………………………………………………………………………………….… 32
8.2.1 Main Board………………………………………………………………………………………………... 32
8.2.2 Power /Inverter/Board……………………………………………………………………………………. 35
8.2.3 Keypad Board…………………………………………………………………………………………….. 37
9. White-Balance, Luminance adjustment………………………………………………………………….… 38
10. EDID Content……………………………………………………………………………………………………. 39
11. BOM List………………………………………………………………………………………………………... 40
http://www.wjel.net
AOC LM923
Page 3 of 55
REVISION LIST
Revision Date Revision History TPV Model
A00 Nov-28-05 First Version Release T980KAXHLFMRA
http://www.wjel.net
AOC LM923
Page 4 of 55
1.MONITOR SPECIFICATIONS
ITEMS SPECIFICATIONS
Driving system TFT LCD
Size 48.0cm(19.0")
Type M190EN02
Pixel pitch 0.294mm( H )x 0.294mm( V )
Viewable angle 170˚ (H) 170˚ (V)
LCD Panel
Response time (type) 25 ms for AU panel
Sync. Type H/V TTL
H-Frequency 30kHz – 83kHz
Input
V-Frequency 55-75Hz
Dot Clock 135MHz
Contrast Ratio 700:1
White Luminance 250cd/m
2
Max. Resolution 1280 x 1024
Plug & Play VESA DDC2B
TM
ON Mode<55W
Power Consumption
OFF Mode<
2W
Power Source 100~240VAC,47~63Hz
Display Color 16.7M colors (RGB 8-bits data)
Maximum Screen Size
Horizontal : 376.32mm
Vertical: 301.056mm
Environmental
Considerations
Operating Temp: 0°C to 40°C
Storage Temp: -20°C to 60°C
Operating Humidity: 15% to 90%
http://www.wjel.net
AOC LM923
Page 5 of 55
2. LCD MONITOR DESCRIPTION
The LCD MONITOR will contain a main board, a power board, a keypad board and an audio board which house the flat
panel control logic, brightness control logic and DDC.
The power board will provide AC to DC Inverter voltage to drive the backlight of panel and the main board chips each
voltage.
HOST Computer
AC-IN
100V-240V
PWPC board
(
Include: ada
p
ter
,
inverter
)
Flat Panel and
CCFL backlight
Main Board
RS232 Connector
For white balance
adjustment in factory
mode
CCFL Drive.
Video signal,
Monitor Block Diagram
Keyboard
Audio board
http://www.wjel.net
AOC LM923
Page 6 of 55
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:
The Left/Right Button is used to control the monitor functions. Press to switch functions or adjust settings.
- 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.
O. Name
Within OSD
Without OSD
1 Auto/Exit Exit OSD or back to previous menu Auto configuration
2 Volume down/
1.Move the cursor to down
2.Decrease the value of the selected item
Activate the volume menu
3 Volume up /
1.Move the cursor to up
2.Increase the value of the selected item
Activate the volume menu
4 MENU/ENTER Select Function or select Sub menu Activate OSD main menu
5 POWER Power On / Off Power On / Off
6 LED Green—On Orange—Save Green—On Orange—Save
http://www.wjel.net
AOC LM923
Page 7 of 55
3.3 ADJUSTING THE PICTURE
Adjustment steps:
1. Press the MENU-button to activate the OSD window.
2. Press < or > to select the desired function.
3. Press the MENU-button to select the function that you want to adjust.
4. Press < or > to change the settings of the current function.
5. To exit and save, select the exit function, or leave the monitor alone for 10 seconds. If you want to adjust any
other function, repeat steps 2-4.
OSD TABLE:
Main Menu
Item
Main Menu
Icon
Sub Menu Item Sub Menu Icon Description
Contrast
Contrast from Digital-register.
Luminance
Brightness
Backlight Adjustment
Focus
Adjust Picture Phase to reduce
Horizontal-Line noise
Image Setup
Clock
Adjust picture Clock to reduce
Vertical-Line noise.
H. Position
Adjust the horizontal position of
the picture.
Image
Position
V. Position
Adjust the vertical position of the
picture.
Warm N/A
Recall Warm Color Temperature
from EEPROM.
Cool N/A
Recall Cool Color Temperature
from EEPROM.
User / Red
Red Gain from Digital-register.
Color Temp.
User / Green
Green Gain Digital-register.
http://www.wjel.net
AOC LM923
Page 8 of 55
User / Blue
Blue Gain from Digital-register.
Yes
N/A
Auto Adjust the H/V Position,
Focus and Clock of picture.
Auto Config
(Analog-Only
Model)
No N/A
Do not execute Auto Config,
return to main menu.
H. Position
Adjust the horizontal position of
the OSD.
OSD Setup
V. Position
Adjust the vertical position of the
OSD.
OSD Timeout
Adjust the OSD timeout.
English N/A
Set OSD display language to
English.
Deutsch N/A
Set OSD display language to
German.
Français N/A
Set OSD display language to
French.
Español N/A
Set OSD display language to
Spain.
Italiano N/A
Set OSD display language to
Italian.
Language
简体中文
N/A
Set OSD display language to
Simplified Chinese.
Information
Information N/A
Show the resolution, H/V
frequency and input port of current
input timing.
Yes N /A
Clear each old status of
Auto-configuration and set the
color temperature to Cool.
Reset
No N/A
Do not execute reset, return to
main menu.
Exit
N/A N/A Exit OSD
http://www.wjel.net
AOC LM923
Page 9 of 55
4. INPUT/OUTPUT SPECIFICATION
4.1 INPUT SIGNAL CONNECTOR
PIN NO. DESCRIPTION PIN NO. DESCRIPTION
1. Red Video 9. +5V
2. Green Video 10.
Detect Cable
3. Blue Video 11.
NC
4. Ground 12. DDC-Serial Data
5. Ground 13. H-Sync
6. Red Ground 14. V-Sync
7. Green Ground 15. DDC-Serial Clock
8. Blue Ground
VGA connector layout
15
6
10
11 15
http://www.wjel.net
AOC LM923
Page 10 of 55
4.2 FACTORY PRESET DISPLAY MODES：
STANDARD
RESOLUTION
HORIZONTAL
FREQUENCY
VERTICAL
FREQUENCY
Dos-mode 720 x 400 31.47kHz 70.0Hz
640 × 480 31.47kHz 60.0Hz
VGA
640 × 480 37.50kHz 75.0Hz
800 × 600 37.879kHz 60.0Hz
SVGA
800 × 600 46.875kHz 75.0Hz
1024 × 768 48.363kHz 60.0Hz
1024 × 768 56.476kHz 70.0Hz
XGA
1024 × 768 60.021kHz 75.0Hz
1280 × 1024 64.000kHz 60.0Hz
SXGA
1280 × 1024 80.000kHz 75.0Hz
4.3 POWER SUPPLY REQUIREMENTS
A/C Line voltage range 100 V ~ 240 V
A/C Line frequency range
50 ± 3Hz, 60 ± 3Hz
Current 1.5A max at 100V; 0.8A max at 240 V
Peak surge current < 55A peak at 240 VAC and cold starting
Leakage current < 3.5mA
Power line surge
No advance effects (no loss of information or defect)
with a maximum of 1 half-wave missing per second
DC output Voltage
5VDC ± 5％; 12VDC± 5％
CURRENT
1.5Amp (5V) ；2 Amp (12V)
http://www.wjel.net
AOC LM923
Page 11 of 55
4.4 PANEL SPECIFICATION
4.4.1 Display Characteristics
4.4.2 Optical Characteristics
http://www.wjel.net
AOC LM923
Page 12 of 55
4.4.3 Parameter guide line for CCFL Inverter
http://www.wjel.net
AOC LM923
Page 13 of 55
5. BLOCK DIAGRAM
5.1 MONITOR EXPLODED VIEW
hinge ass’y 37G 490 1
Key pad 33G4713 AS L
clam
p
33G4695 -1-C
bezel 34G1275AKG-3B
rear cover 34G1276-GM -4B
stand 34G1273-GM-B
base 34G1277-GM-B
main frame 15G6093 AU
shield 85G6081-5
http://www.wjel.net
AOC LM923
Page 14 of 55
5.2 SOFTWARE FLOW CHART
1
2
N
Y
5
Y
N
10
Y
N
12
Y
N
7
N
6
4
3
9
14
11
13
Y
N
15
Y
N
16
17
19
Y
N
18
http://www.wjel.net
AOC LM923
Page 15 of 55
1) MCU initialize.
2) Is the EPROM blank?
3) Program the EPROM by default values.
4) Get the PWM value of brightness from EPROM.
5) Is the power key pressed?
6) Clear all global flags.
7) Are the AUTO and SELECT keys pressed?
8) Enter factory mode.
9) Save the power key status into EPROM.
Turn on the LED and set it to green color.
Scalar initializes.
10) In standby mode?
11) Update the lifetime of back light.
12) Check the analog port, are there any signals coming?
13) Does the scalar send out an interrupt request?
14) Wake up the scalar.
15) Are there any signals coming from analog port?
16) Display "No connection Check Signal Cable" message. And go into standby mode after the message
disappear.
17) Program the scalar to be able to show the coming mode.
18) Process the OSD display.
19) Read the keyboard. Is the power key pressed?
http://www.wjel.net
AOC LM923
Page 16 of 55
5.3 ELECTRICAL BLOCK DIAGRAM
5.3.1 Main Board
MCU
W78E65
(U601)
Scalar IC MST8111B
(Include ADC, OSD)
(U401)
EEPROM
AT24C16N
(U602)
EEPROM
24C02
(U301)
H sync
V sync
RGB
DB15_SDA,
DB15
_
SCL
EPR_SDA
EPR_SCL
LCD Interface
(CN503)
Key Board
Control
D-Sub
Connector
(CN301)
Crystal
14.318MHZ
(X401)
http://www.wjel.net
AOC LM923
Page 17 of 55
5.3.2 Inverter/Power Board
CN902
DIM
DIM
EMI filter
Bridge
Rectifier
and Filter
Start Circuit: R906、 R907
PWM
Control IC
Transformer
Rectifier
diode
AC input
12V
ON/OFF
Control
PWM
Control IC
Feedback
Circuit
OSC and
Output
Circuit
DC Convert
Circuit
MOSFET
Over
Voltage
Lamp
Feedback
Circuit
Over
Voltage
Protect
http://www.wjel.net
Loading...
+ 38 hidden pages
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use