AOC LM923 User manual

AOC LM923
Page 1 of 55
SERVICE MANUAL
19” LCD MONITOR
LM923
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 RELIABILITY FOR CHANGES,
ERRORS OR OMISSIONS.
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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
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AOC LM923
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REVISION LIST
Revision Date Revision History TPV Model
A00 Nov-28-05 First Version Release T980KAXHLFMRA
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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/m2
Max. Resolution 1280 x 1024
Plug & Play VESA DDC2BTM
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%
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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
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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:
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
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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.
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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
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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
610
11 15
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AOC LM923
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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)
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4.4 PANEL SPECIFICATION
4.4.1 Display Characteristics
4.4.2 Optical Characteristics
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4.4.3 Parameter guide line for CCFL Inverter

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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
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AOC LM923
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5.2 SOFTWARE FLOW CHART
1
2
N
Y
5
Y
N
10
Y
N
12
Y
N
7
Y
N
6
4
3
8
9
14
11
13
Y
N
15
Y
N16
17
19
Y
N
18
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AOC LM923
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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?
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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)
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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
ON/OFF
Feedback
Circuit
Over
Voltage
Protect
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AOC LM923
Page 18 of 55
6. SCHEMATIC
6.1 MAIN BOARD
715L1237-1
VAA2
VAA1
VCC3.3
B1
3.INPUT
RIN
GIN
BIN
VSYNC
GNDR
GNDG
GNDB
ST_DET1 HSYNC
SOGDDC_CLK
DDC_DAT
ST_DET2
R+
R-
G-
G+
B+
B-
CLK+
CLK-
TXD
RXD
VCPU
TOP
D
B
16Wednesday, November 10, 2004
Title
Size Document Number Rev
Date: Sheet of
VCC5V
B3
6.MCU
onBACKLITE
ST_DET2
onPANEL_5V/3.3V
SDA
INT
CSZ
DDC_DAT
ST_DET1
SCL
HWRESET
DDC_CLK
Volume
VCC5V
VCC12V
VCPU
RXD
TXD
AD0
AD1
AD2
AD3
VCC3.3VCC2.5
VCC5VVCPU
B4
2.POWER
onPanel_5V/3.3V
onBACKLITE
AdjBACKLITE
VCC3.3
VCC2.5
VAA1
VAA2
VAA3
VAA4
VCC5V
VCC12V
VLCD
VCPU
VLCD
VAA4
VAA3
VAA2
VAA1
B5
5.PANEL INTERFACE
VLCD
PB[0..9]
PA[0..9]
VLCD
VCC2.5
PA[0..9]
MST 8011/8111 FOR AOC
PB[0..9]
B2
4.SCALER
RIN
GIN
SOG
BIN
GNDR
GNDG
GNDB
HSYNC
VSYNC
R+
R-
G-
G+
B+
B-
CLK+
CLK-
CSZ
SCL
SDA
HWRESET
INT
Volume
AdjBACKLITE
PA[0..9]
PB[0..9]
VCC2.5
VCC3.3
VAA1
VAA2
VAA3
VAA4
AD0
AD1
AD2
AD3
VAA4
MST 8011/8111 SCHEMATIC
VAA3
VCC12V
VCC12V
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GND
VCC12V
R209
0 1/16W
ON_OFFGND
C207
0.1uF
VCC5V+
R216
4.7K 1/16W
Brightness
CN201
CONN
2
4
6
8
10
12
1
3
5
7
9
11
R204
10K 1/16W
VAA4 4
VCPU 6
D202
GS1D
R205 4.7K 1/16W
VCC5V
VCC12V
VCC5V+
R207
4.7K 1/16W
D201 SS14
C217
0.068uF
VCC5V
GND
MST 8011/8111 FOR AOC
R214 delete
Q201
PMBS3904
32
1
C214
0.1uF
VAA3 4
C201
0.1uF
R212 4.7K 1/16W
R201 4.7K 1/16W
VCC5V
VCC2.5
VCC12V
VAA2
U202
AIC1084-33M
3
1
2
VIN
ADJ
VOUT
R210
NC
VAA4
VCC5V
VCC3.3 4
C203
0.1uF
Q203
AO3401
+
C215
47uF/16V
GND
C210
0.1uF
C
BE
VCC2.5 4
C216
0.1uF
POWER
D
B
26Wednesday, November 10, 2004
Title
Size Document Number Rev
Date: Sheet of
GND
VAA1
C205
0.1uF
VAA3
VCC5V 3,4,6
+
C202
220uF/25V
VCC3.3
Q204
PMBS3904
32
1
+
C208
100uF/16V
SOT-252
R202
10K 1/16W
R215
100K 1/16W
FB201
600 OHM
U201
RT9164
3 2
1
VI VO
GND
VCC5V
VCPU
R208
10K 1/16W
DIM
R213
NC
C206
1uF/25V
R203
1K 1/16W
VCC5V+
VAA2 4
onBACKLITE 6
VLCD 5
AdjBACKLITE4
TO-263
VCC5V VCC3.3
VCC12V
C
BE
NEW
Circuit
VCC5V
VCC5V
VCC12V 6
R206
10K 1/16W
+
C204
220uF/25V
+
C211
47uF/16V
R211
10K 1/16W
GND
C212
0.1uF
VAA1 4
onPanel_5V/3.3V6
Q202
PMBS3904
32
1
VLCD
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VCC5V
VSI
VGA_CON
C313
0.1uF
R304 470 1/16W
VCC5V
D312
BAV99
3
1 2
R320 100 1/16W
D305
BAV70
1
2 3
R- 4
U302
M24C02WMN6
1
2
3
45
6
7
8A0
A1
A2
GNDSDA
SCL
WP
VCC
D309
BAV99
3
1 2
D316
LL5232B 5.6V 5%
D304
BAV70
1
2 3
DVI5V
HSYNC 4
DDC_CLK6
C307 0.001uF
TXD 6
GNDR 4
CN301
DB15
1
6
2
7
3
8
4
9
5
11
12
13
14
15
10
FB301 0 1/16W
C302
NC
C310 0.047uF
R313
2.2K 1/16W
C308 0.047uF
D303
BAV99
3
1 2
GNDB 4
D311
BAV99
3
1 2
R301 100 1/16W
R315 100 1/16W
R307 100 1/16W
VCC5V
C304 0.047uF
BIN 4
D321
TZMC5V6-GS08
D318
TZMC5V6-GS08
DAT_DDC2
C314
0.1uF
FB303 0 1/16W
DDC_DAT6
R309 100 1/16W
FB304 150 OHM
C301
NC
D323
TZMC5V6-GS08
R321
10K 1/16W
R305 100 1/16W
CLK+ 4
R318
10K 1/16W
RIN 4
DVI5V
R323
10K 1/16W
R317
10K 1/16W
B- 4
VSYNC 4
G+ 4
D322
TZMC5V6-GS08
HSI
D313
BAV99
3
1 2
VCC5V
R324
10K 1/16W
C315
0.1uF
MST 8011/8111 FOR AOC
D306
BAV99
3
1 2
CLK- 4
R316 100 1/16W
ST_DET2 6
CLK_DDC2
D308
BAV99
3
1 2
R327
75 1/16W
R302 100 1/16W FB302 0 1/16W
D310
BAV99
3
1 2
R+ 4
INPUT
D
B
36Wednesday, November 10, 2004
Title
Size Document Number Rev
Date: Sheet of
CLK_DDC
GIN 4
C309 0.047uF
D314
LL5232B 5.6V 5%
PC5V
R314
10K 1/16W
DAT_DDC
CN302
JACK
1
2
3
4
5
6
7
8
25
28
9
10
11
12
13
14
15
16
26
29
17
18
19
20
21
22
23
24
27
DAT2-
DAT2+
2/4shield
DAT4-
DAT4+
DDC SCL
DDC SDA
VSYNC
R
HSYNC
DAT1-
DAT1+
1/3shield
DAT3-
DAT3+
+5V
SYNC GND
HPD
G
RGB GND
DAT0-
DAT0+
0/5shield
DAT5-
DAT5+
clk shield
clk+
clk-
B
R312 100 1/16W
C306 0.047uF
D317
TZMC5V6-GS08
C303
NC
GNDG 4
SOG 4
R303 100 1/16W
C311
33pF
PC5V
C305 0.047uF
R306 100 1/16W
D301
BAV99
3
1 2
C312
220pF
R325
75 1/16W
R322 100 1/16W
R326
75 1/16W
R308
10K 1/16W
ST_DET1 6
D315
LL5232B 5.6V 5%
G- 4
VCC5V
R310 1K 1/16W
R319 100 1/16W
D319
TZMC5V6-GS08
D307
BAV99
3
1 2
U301
M24C02WMN6
1
2
3
45
6
7
8A0
A1
A2
GNDSDA
SCL
WP
VCC
D302
BAV99
3
1 2
D320
TZMC5V6-GS08
B+ 4
RXD 6
R311 1K 1/16W
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