AOC LM926 User manual
19ƎLCD Color Monitor AOCLM926
1
Service
Service
Service
Horizontal Frequency
30-83 kHz
TABLEOFCONTENTS
Description Page Description Page
N
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.
Table Of Contents.......……..............................…........1
Revision List.…........................................……......2
Important Safety Notice.…….........................……......3
1.Monitor Specification..............................………........4
2.LCD Monitor Description…………………………….......5
3.Operation Instruction……………...............……...........6
3.1.General Instructions………..........................…...........6
3.2.Control Button…………….…..............……...............6
3.3.Adjusting the Picture...........................…............8
4.Input/Output Specification............……………............10
4.1.Input Signal Connector............……………...............10
4.2 Power Supply Requirement………..…………………11
4.3.Factory Preset Display Modes……….......................11
4.4.Panel Specification.....……...……………..................12
5.Block Diagram………...................…….……................15
5.1.Software Flow Chart…………………..………...........15
5.2.Electrical Block Diagram….………….……..….......17
6.Schematic…………………...................................…19
6.1.Main Board.................................................19
6.2 Power Board....…..….….......................................24
6.3. Audio Board.....………..…....................................26
7.PCB Layout..……………….......................................27
7.1.Main Board……………........................................27
7.2 Power Board.....…..….….......................................30
7.3. Audio Board.....………..…....................................33
7.4.Key Board…………...…….....................................34
8.Maintainability…………….........................................35
8.1.Equipments and Tools Requirement…..................35
8.2.Trouble Shooting…………………..........................36
9.White-Balance Luminance adjustment………….....42
10.Monitor Exploded View……………….……….........43
11.BOM List………......................................................44
CAUTION: USE ASEPARATE ISOLATION TRANSFOMER FOR THIS UNIT WHEN SERVICING
19ƎLCD Color Monitor AOCLM926
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Revision List
Revision Date Revision History TPV Model
A00 May-23-07 Initial Release T96HM6DLG3CKA
19ƎLCD Color Monitor AOCLM926
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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 NOTICESARE
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 byAOC 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 asAOC.
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 openAVOID 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.)
19ƎLCD Color Monitor AOCLM926
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1. Monitor Specifications
Items Descriptions
Driving system TFT Color LCD
Size 48cm (19")
Pixel pitch 0.294mm( H )x 0.294mm( V )
Viewable angle 140Û(H) 135Û(V)
LCD Panel
Response time (type) 8 ms
R,G,B Analog Interface
Video Digital Interface
15-pin D-Sub
Connector DVI 24pin
Analog:0.7Vp-p(standard),
75 OHM, Positive
Video Signal
Digital signal
Separate Sync. H/V TTL
H-Frequency 30kHz – 83kHz (Analog)
Input
V-Frequency 55-75Hz (Analog)
ON Mode 55W
EPA ENERGY STAR®OFF Mode 2W
Dot Clock 135 MHz(Analog)
Max. Resolution 1280 x 1024@75Hz(Analog)
Display Color 16.2M colors
Plug & Play VESA DDC2BTM
Power Source 100~240VAC,47~63Hz
Maximum Screen Size Horizontal : 376.32 mm
Vertical: 301.056 mm
Environmental
Considerations
Operating Temp: 5°C to 50°C
Storage Temp: -20°C to 60°C
Operating Humidity: 10% to 85%
Weight (N. W.) 5Kgs Unit (net)
Dimensions 406 (W) x 406 (H) x 222 (D)mm
19ƎLCD Color Monitor AOCLM926
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2. LCD Monitor Description
The LCD monitor will contain a main board, an audio board, a power board and a key board which house the flat
panel control logic, brightness control logic and DDC.
The power board will provideAC to DC Inverter voltage to drive the backlight of panel and the main board chips
each voltage.
Monitor Block Diagram
AC-IN
100V-240V
Power Board
(
Include: ada
p
ter
,
inverter
)
Flat Panel and
CCFL backlight
RS232 Connector
For white balance
adjustment in factory
mode
CCFL Drive.
Video signal, DDC
Key Board
HOST Computer
Audio Board
Main Board
19ƎLCD Color Monitor AOCLM926
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3. Operating Instructions
3.1 General Instructions
Press the power button to turn the monitor on or off. The 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
External Control Button
EXTERNAL CONTROLS
1. Auto Adjust button / Exit
2. /Volume down
3. / Volume up
4. MENU / ENTER
5. Power Button
6. LED
19ƎLCD Color Monitor AOCLM926
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Connecting Cables
1. Power Cable
2. 15-pin D-Sub Cable
3. DVI Cable
4. Audio Cord
FRONT PANEL CONTROL
xPower Button:
Press this button to turn the monitor ON or OFF.
xPower Indicator:
Green — Power On mode.
Orange — Off mode.
xMENU / ENTER:
Active OSD menu or function adjust confirm or Exit OSD menu when in volume OSD status.
xVolume / :
Increase volume or adjust function.
xVolume / :
Decrease volume or adjust function.
xAuto Adjust button / Exit:
1. When OSD menu is in active status, this button will act as EXIT-KEY (EXIT OSD menu).
2. When OSD menu is in off status, press this button to activate the Auto Adjustment function.
The AutoAdjustment function is used to optimized the HPos, VPos, Clock and Focus.
OSD Lock Function: To lock the OSD, press and hold the MENU button while the monitor is off and then press
power button to turn the monitor on. To un-lock the OSD - press and hold the MENU button while the monitor is off
and then press power button to turn the monitor on.
19ƎLCD Color Monitor AOCLM926
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3.3 Adjusting the Picture
1. Press the MENU-button to activate the OSD window.
2. Press or to navigate through the functions. Once the desired function is highlighted, press the
MENU-button to activate it. If the function selected has a sub-menu, press or again to navigate through
the sub-menu functions. Once the desired function is highlighted, press MENU-button to activate it.
3. Press or to change the settings of the selected function.
4. To exit and save, select the exit function. If you want to adjust any other function, repeat steps 2-3.
The OSD Message
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.
19ƎLCD Color Monitor AOCLM926
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User / Blue
Blue Gain from Digital-register.
Analog
N/A Select input signal from analog source (D-Sub)Input Select
Digital N/A Select input signal from digital source (DVI)
H. Position
Adjust the horizontal position of the OSD.
V. Position
Adjust the vertical position of the OSD.
OSD Setup
OSD Timeout
Adjust the OSD timeout.
Language
Language N/A Set OSD language.
Information
Information N/A Show the resolution, H/V frequency and input port of
current input timing.
Yes N/A Clear each old status ofAuto-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
19ƎLCD Color Monitor AOCLM926
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4. Input/Output Specification
4.1 Input Signal Connector
1. D-SUB connector
Pin No. Description Pin 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
2. DVI-D connector
Pin No. Description Pin No. Description
1. TMDS data 2Ё13. TMDS data 3Ѐ
2. TMDS data 2Ѐ14. Ѐ5V Power
3. TMDS data 2/4 Shield 15. GND (for +5V)
4. TMDS data 4Ё16. Hot Plug Detect
5. TMDS data 4Ѐ17. TMDS data 0Ё
6. DDC Clock 18.
TMDS data 0Ѐ
7. DDC Data 19. TMDS data 0/5 Shield
8. NC 20.
TMDS data 5Ё
9. TMDS data 1Ё21. TMDS data 5+
10. TMDS data 1Ѐ22. TMDS Clock Shield
11. TMDS data 1/3 Shield 23. TMDS Clock +
12. TMDS data 3Ё24. TMDS Clock Ё
24 - Pin Color Display Signal Cable
19ƎLCD Color Monitor AOCLM926
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4.2 Power Supply Requirement
A/C Line voltage range : 100 V ~ 240 V
A/C Line frequency range : 50 r3Hz, 60 r3Hz
Current : TBD
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 : 12VDC ± 5и
Current (max) : 3.5 Amp (12V)
4.3 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
Note: The factory preset mode for DOS is 720x400 @70Hz.
19ƎLCD Color Monitor AOCLM926
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4.4 Panel Specification
4.4.1 Introduction
4.4.2 Display Characteristics
19ƎLCD Color Monitor AOCLM926
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4.4.3 Optical Characteristics
19ƎLCD Color Monitor AOCLM926
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4.4.4 Electrical Characteristics
1. TFT LCD Module
2. Backlight Unit
19ƎLCD Color Monitor AOC LM926
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5. Block Diagram
5.1 Software Flow Chat
1
2
N
Y
5
Y
N
1
Y
N
12
Y
N
7
Y
N
6
4
3
8
9
14
11
13
Y
N
15
Y
N 16
17
19
Y
N
18
19ƎLCD Color Monitor AOC LM926
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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 theAUTO 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?
19ƎLCD Color Monitor AOC LM926
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5.2 Electrical Block Diagram
5.2.1 Main Board
EEPROM
M24C16
(U403)
Flash Memory
PM25LV512-25SCE
(U402)
Scalar IC TSUM56AK
(Include MCU, ADC, OSD)
(U401)
EEPROM
M24C02
(U404)
H sync
V sync
RGB
SCL_VGA,
SDA_VGA
LCD Interface
(CN101)
D-Sub
Connector
(CN405)
Crystal
14.318MHz
(X401)
DVI
Connector
(CN406)
EEPROM
M24C02
(U405)
Digital
Video
Signal
SCL_DVI,
SDA_DVI
Key Board
Control
(CN403)
19ƎLCD Color Monitor AOC LM926
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5.2.2 Inverter/Power Board
19"LCDColorMonitor AOC LM926
19
6. Schematic
6.1 Main Board
715G1558 2 2
VLCD_12V
PB[6..11]
PA[8..13]
VCC1.8
B4
4.SCALER
RIN
GIN
SOG
BIN
GNDR
GNDG
GNDB
HSYNC
VSYNC
Adj_BACKLIGHT
VCC1.8
Vcc3.3
VCTRL
PA[0..7]
PA[8..13]
R+
R-
G-
G+
B+
B-
CLK+
CLK-
DDCD_SDA
DDCD_SCL
DET_DVI
DDCA_SDA
DDCA_SCL
DET_VGA
on_BACKLIGHT
on_Panel
+5V
PA[14..19]
PB[0..5]
PB[6..11]
GPO[0..4]
ESP
OSP
on_PANEL_12V
PB[12..23]
+12V
DDC_WP
VCC3.3
LVDS OUTPUT
+12V
PA[14..19]
VLCD
GPO[0..4]
VCC1.8 VLCD_12V
B3
3.INPUT
RIN
GIN
BIN
VSYNC
GNDR
GNDG
GNDB
DET_VGA
HSYNC
SOG
B+
CLK-
DET_DVI
CLK+
R+
G+
R-
B-
G-
DDCA_SDA
DDCA_SCL
DDCD_SDA
DDCD_SCL
+5V
DDC_WP
+3V3
TSUM56AK SCHEMATIC
TSUM56AK
TOP
A
B
05Monday, May 09, 2005
Title
Size Document Number Rev
Date: Sheet of
VLCD
+5V
+5V
XGA/SXGA
+5V
VCC3.3
PC5V PB[12..23]
PA[0..7]
B5
5.PANEL INTERFACE
VLCD
PA[0..7]
PA[8..13]
ESP
PA[14..19]
PB[0..5]
PB[6..11]
GPO[0..4]
OSP
VLCD_12V
PB[12..23]
B2
2.POWER
on_Panel
on_BACKLIGHT
Adj_BACKLIGHT
+3V3
VCC1.8
VLCD
+5V
VCTRLPC5V
VCC5V
VCC3.3
on_PANEL_12V
VLCD_12V
+12V
VCC5V
+12V
PB[0..5]
19"LCDColorMonitor AOC LM926
20
TSUM56AK
R716
NC
R720 0 1/16W
ǂ
R704
100 1/16W
ǂ
R32
1UF
P.S: The 1N4148 Vf=0.7V~1V can't meet
LDO spec. The BAT42, Vf is OK but the
If=200mA(forward current) can not
meet current spec.
VLCD 5
For RSDS and Panel VCC=12V
C704
NC
Q701
PMBS3904
VLCD_12V 5
+3V3
+3V3
Adj_BACKLIGHT
4
+5V3,4 PC5V 3
PC5V
BL_ADJ(DC)
C32
C718
0.1uF
+5V
X
+5V
R715
NC
TO-263
+3V3
+
C707
100uF/25V
C715
0.1uF
GND
+5V
H1
TP
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
R725
4.7K 1/16W
ǂ
+12V
Q705
AO3401L
1K
+3V3
R726 NC/4K7
C708
1uF
+
C710
100uF/25V
POWER
A
B
15Monday, May 09, 2005
Title
Size Document Number Rev
Date: Sheet of
+12V
R732
10 1/16W
ǂ
R31
R705 4.7K 1/16W
ǂ
+3V3
VCC1.8 4
X
+5V
CN701
CONN
2
4
6
8
10
12
1
3
5
7
9
11
0
C714
0.1uF
+12V
+5V
VLCD
+5V
H3
TP
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
R722
NC
1uF
Q707
PMBS3904
on_BACKLIGHT 4
P W M
D702
1N4148
MMBT3904
VCTRL 4
4.7K
R729
NC/10K
+5V3,4
+5V
C51
C709
0.1uF
GND
4K7
+5V
C720
NC/0.1uF
U702
AIC1084-33PM
3
1
2
4
VIN
ADJ
VOUT
VOUT
R721
0 1/16W
ǂ
VCC3.3 4
R707
4.7K 1/16W
ǂ
VLCD_12V
VCC1.8
R713
NC
+
C702
4.7uF/16V
R723 51K 1/16W
ǂ
+
C717
10uF/16V
R714
10K 1/16W
ǂ
GND VCC3.3 4
C713
0.1uF
+5V
GND
R730
0 1/16W
ǂ
+5V
R710 NC
D C
Q703
PMBS3904
Recommond to used "Blue" parts circuit
for VCC1.8V if you want to suppoert DDC
function when system power off
0V ~ 3.3V
C716
0.1uF
R703
2K 1/16W
ǂ
+5V
R706 NC
Q706
PMBS3904
1UF
VCC5V
C701
NC
+
C703
100uF/25V
4.7K
R717
10K 1/16W
ǂ
N.C
R29
R708
10K 1/16W
ǂ
+12V
R701
1K 1/16W
ǂ
47
R728
NC/4K7
+
C705
1uF/16V
D704
SMAL140
on_Panel_12V4
X
D704(SSM12L) Vf=0.38V and If=1A.
So when system power on, the
system loading is about 400mA
(3.3V is about 200mA and 1.8V is
about 200mA), So D35 changed
from 1N4148(or BAT42) to
SSM12L(schottky diode).
C711
0.1uF
VCC3.3
BL_ADJ
R731
NC
R709
0 1/16W
ǂ
R724 51K
+12V 4
+5V3,4
D701
1N4148
+12V
SOT-223
X
12/21 MODIFY
C706
0.1uF
on_Panel4
R719
NC/10K
R712 4.7K 1/16W
ǂ
D703
BAT54C
3
1
2
+5V
+
C719
NC/10uF/16V
+
C712
100uF/25V
R727
10K 1/16W
ǂ
BL_ADJ
R702
51 1/16W
ǂ
H2
TP
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
0V ~ 5V
R33
BL_ON
GND GND
R711
10K 1/16W
ǂ
U701
NC/LT1117-18
3 2
1
4
VI VO
GND
VO
Q4
Q702
CHT2907
C
B
E
+5V
R718
NC/10K
4.7K
R31
Q704
AO3401L
VCC3.3
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