AOC LM725 User manual

AOC LM725
1
17” LCD MONITOR
LM725
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.
SERVICE MANUAL

AOC LM725
2
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 Front Panel Control…………………………………………………………………………………….……... 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………………………………………………………………………………… 11
4.4 Panel Specification………………………………………………………………………………………….… 11
4.4.1 Panel Feature……………………………………………………………………………….……………. 11
4.4.2 Display Characteristics……………………………………………………………….………………….. 11
4.4.3 Optical Characteristics…………………………………………………………………………………… 12
4.4.4 Electrical Characteristics………………………………………………………………………………… 13
5. Block Diagram………………………………………………………………………………………………….… 14
5.1 Monitor Explored View………………………………………………………………………………………... 14
5.2 Software Flow Chart…………………………………………………………………………………………... 15
5.3 Electrical Block Diagram……………………………………………………………………………………… 17
5.3.1 Main Board……………………………………………………………………………………………….. 17
5.3.2 Inverter/Power Board……………………………………………………………………………………. 18
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………………………………………………………………………….……………………….. 28
7.3 Audio Board………………………………………………………………………….………………………… 29
7.4 Keypad Board…………………………………………………………………………………………………. 29
8. Maintainability……………………………………………………………………………………………………. 30
8.1 Equipments and Tools Requirement………………………………………………………………………… 30
8.2 Trouble Shooting…………………………………………………………………………………………….… 31
8.2.1 Main Board………………………………………………………………………………………………... 31
8.2.2 Power /Inverter/Board…………………………………………………………………………………… 34
8.2.3 Keypad Board…………………………………………………………………………………………….. 36
9. White-Balance, Luminance adjustment………………………………………………………………….….. 37
10. EDID Content……………………………………………………………………………………………………. 38
11. BOM List ………………………………………………………………………………………………………... 39

AOC LM725
3
Revision List
Version Date Revision History TPV Model Name
A00 Mar-09-06 Initial Revision T782KSQHMCPGA

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1. Monitor Specifications
Items Description
Driving system TFT Color LCD
Type LTM170EU-L21
Size 43.2cm (17.0")
Pixel pitch 0.264mm (H) x 0.264mm (V)
Viewable angle 150(H) 135(V) (CR≥10)
LCD Panel
Response time (type) 8 ms
Sync. Type H/V TTL
15Pin Analog
Input Signal 24Pin Digital
H-Frequency 30kHz – 80kHz
Input
V-Frequency 55-75Hz
ON Mode ≤45W
Power Consumption OFF Mode ≤2W
Display Color 16.2M
Contrast Ratio 700:1
Dot Clock 135MHz
White Luminance 300cd/m2
Max. Resolution 1280 x 1024
Plug & Play VESA DDC2BTM
Power Source 100~240VAC,47~63Hz
Maximum Screen Size Horizontal : 337.920mm
Vertical: 270.336mm
Environmental
Conditions
Operating Temp: 5°C to 35°C
Storage Temp: -20°C to 60°C
Operating Humidity: 10% to 85%

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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 position. The power indicator will light up.
3.2 Front Panel Control
- 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.
NO. Name Within OSD Without OSD
1 Auto Exit OSD or back to previous menu Auto configuration
2 VOL- / 1.Move the cursor to left
2. Decrease the value of the selected item Activate the volume menu
3 VOL+ / 1.Move the cursor to right
2.Adjust up when menu item selected Activate the volume menu
4 MENU Select Function or select Sub menu Activate OSD main menu
5 Power Power On / Off Power On / Off
6 Indicate light Green—On Orange—Save Green—On Orange—Save

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3.3 Adjusting The Picture
The Description For Control Function:
Main Menu Item
Main
Menu
Icon
Sub Menu Item
Sub
Menu
Icon
Description Reset Value
Contrast Contrast from Digital-register. Recall Cool
Contrast Value
Luminance Brightness Backlight Adjustment Recall Cool
Brightness Value
Focus
Adjust Picture Phase to reduce
Horizontal-Line noise Do Auto Config
Image Setup Clock
Adjust picture Clock to reduce
Vertical-Line noise. Do Auto Config
H. Position
Adjust the horizontal position of the
picture. Do Auto Config
Image Position V. Position
Adjust the vertical position of the
picture. Do Auto Config
C1 N/A
Recall Warm Color Temperature from
EEPROM.
C2 N/A
Recall Cool Color Temperature from
EEPROM.
User / Red Red Gain from Digital-register.
User / Green Green Gain Digital-register.
Color Temp.
User / Blue Blue Gain from Digital-register.
The Color
Temperature will
be set to Cool.
Analog N/A
Select input signal from analog
source (D-Sub) N/A
Input Select Digital N/A
Select input signal from digital source
(DVI) N/A

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H. Position
Adjust the horizontal position of the
OSD. 50
V. Position
Adjust the vertical position of the
OSD. 50
OSD Setup
OSD Timeout Adjust the OSD timeout. 10
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.
The Language
will be set to
English.
Information Information N/A
Show the resolution, H/V frequency
and input port of current input timing. N/A
Yes N/A
Clear each old status of
Auto-configuration and set the color
temperature to Cool.
N/A
Reset
No N/A
Do not execute reset, return to main
menu. N/A
Exit N/A N/A Exit OSD N/A

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4. Input/Output Specification
4.1 Input Signal Connector
Pin No. Description Pin No. Description
1. Red 9. +5V
2. Green 10. Logic Ground
3. Blue 11. Monitor Ground
4. Monitor Ground 12. DDC-Serial Data
5. DDC-Return 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
Frequenc
y
+/- 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@70Hz 1328x806 56.476 N 70.069 N 75.000
XGA
1024x768@75Hz 1312x800 60.023 P 75.029 P 78.750
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
2Mode Resolution Total
Nominal
Frequenc
y
+/- 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
DOS 640x350@70Hz 800 x 449 31.469 P 70.087 N 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

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4.3 Power Supply Requirement
A/C Line voltage range 100 V ~ 240 V
A/C Line frequency range 50 ±3Hz, 60 ±3Hz
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± 5％
4.4 Panel Specification
4.4.1 Panel Feature
 High contrast ratio, high aperture structure
 TN(Twisted Nematic) mode
 Wide viewing angle
 High speed response
 SXGA(1280 x 1024 pixels) resolution
 Low power consumption
 2 dual CCFTs(Cold Cathode Fluorescent Tube)
 DE(Data Enable) mode
 LVDS (Low Voltage Differential Signaling) interface (2pixel/clock)
 Compact size design
 Pb-free configuration
 RoHS compliance
4.4.2 Display Characteristics

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4.4.3 Optical Characteristics
* Ta = 25 ± 2°C, VDD=5V, fv= 60Hz, fDCLK=54MHz, IL = 6.5mArms

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4.4.4 Electrical Characteristics
1. TFT LCD Module:
2. Back Light Unit:

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5. Block Diagram
5.1 Monitor Exploded View

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5.2 Software Flowing 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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REMARK:
1) MCU initialize.
2) Is the EEprom blank?
3) Program the EEprom by default values.
4) Get the PWM value of brightness from EEprom.
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 EEprom.
Turn on the LED and set it to green color.
Scalar initialize.
10) In standby mode?
11) Update the lifetime of back light.
12) Check the analog port, are they’re 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 MST8131B
(Include ADC, OSD)
(U401)
EEPROM
24LC16B
(U602)
EEPROM
M24C02
(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)
Crystal
20MHZ
(X601)
D-Sub
Connector
(CN302)
EEPROM
M24C02
(U302)
DDC2_SDA,
DDC2_SCL
D-Data
D-Clock

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5.3.2 Inverter/Power Board
CN102
DIM
DIM
EMI filter
Bridge
Rectifier
and Filter
Start Circuit: R906、R907
PWM
Control IC
Transformer Rectifier
diodes
AC input
12V
ON/OFF
Control
PWM
Control IC
Feedback
Circuit
OSC and
Output
Circuit DC Convert
Circuit MOSFET
Over
Voltage
Protect
Lamp
ON/OFF
Feedback
Circuit
Over
Voltage
Protect

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6. Schematic
6.1 Main Board
715L1237-1
VCC5V
PA[0..9]
VCC2.5
VCC2.5
VAA2
VCC3.3 VAA4
VCC12V
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
VAA3
TOP
D
MST8031 / MST8131 for AOC
B
16Wednesday, April 14, 2004
Title
Size Document Number Rev
Date: Sheet of
VCPU
VCC3.3
PB[0..9]
VCPU
VLCD
MST8031/8131 SCHEMATIC
VCC5V
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
VAA1
VLCD
VAA2VAA1
VCC12V
VAA4
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
B4
2.POWER
onPanel_5V/3.3V
onBACKLITE
AdjBACKLITE
VCC3.3
VCC2.5
VAA1
VAA2
VAA3
VAA4
VCC5V
VCC12V
VLCD
VCPU
B5
5.PANEL INTERFACE
VLCD
PB[0..9]
PA[0..9]
VAA3

AOC LM725
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R302 100 1/16W
D323
TZMC5V6-GS08
D319
TZMC5V6-GS08
VCC5V
CN301
DB15
1
6
2
7
3
8
4
9
5
11
12
13
14
15 10
R304 470 1/16W
D321
TZMC5V6-GS08
R310 1K 1/16W
C309 0.047uF
VSYNC 4
GNDB 4
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
R313
2.2K 1/16W
FB303 0 1/16W
D312
BAV99
3
1 2
B+ 4
VSI
DAT_DDC
VCC5V
DAT_DDC2
R327
75 1/16W
D307
BAV99
3
1 2
D308
BAV99
3
1 2
D318
TZMC5V6-GS08
C314
0.1uF
R- 4
D320
TZMC5V6-GS08
R325
75 1/16W
C307 0.001uF
R308
10K 1/16W
ST_DET2 6
D317
TZMC5V6-GS08
R320 100 1/16W
C302
NC
D302
BAV99
3
1 2
R316 100 1/16W
CLK- 4
U302
M24C02WMN6
1
2
3
45
6
7
8A0
A1
A2
GNDSDA
SCL
WP
VCC
CLK_DDC2
C303
NC
R319 100 1/16W
VGA_CON
R306 100 1/16W
C312
220pF
D313
BAV99
3
1 2
R+ 4
R309 100 1/16W
DDC_DAT6
C310 0.047uF
D310
BAV99
3
1 2
C315
0.1uF
D306
BAV99
3
1 2
PC5V
D322
TZMC5V6-GS08
BIN 4
G+ 4
CLK_DDC
GNDG 4
R324
10K 1/16W
R307 100 1/16W
D301
BAV99
3
1 2
D315
LL5232B 5.6V 5%
C301
NC
C311
33pF
B- 4
HSI
R326
75 1/16W
SOG 4
R301 100 1/16W
D309
BAV99
3
1 2
D314
LL5232B 5.6V 5%
C304 0.047uF
R317
10K 1/16W
CLK+ 4
R311 1K 1/16W
R314
10K 1/16W
FB302 0 1/16W
ST_DET1 6
D303
BAV99
3
1 2
C306 0.047uF
R312 100 1/16W
VCC5V
R315 100 1/16W
G- 4
RXD 6
R323
10K 1/16W
C313
0.1uF
VCC5V
D311
BAV99
3
1 2
GNDR 4
C308 0.047uF
R318
10K 1/16W
FB304 150 OHM
D316
LL5232B 5.6V 5%
D304
BAV70
1
2 3
R322 100 1/16W
U301
M24C02WMN6
1
2
3
45
6
7
8A0
A1
A2
GNDSDA
SCL
WP
VCC
TXD 6
HSYNC 4
DDC_CLK6
PC5V
INPUT
D
MST8031/ MST8131 for AOC
B
36Tuesday, November 09, 2004
Title
Size Document Number Rev
Date: Sheet of
R305 100 1/16W
RIN 4
DVI5V
VCC5V
GIN 4
C305 0.047uF
DVI5V
FB301 0 1/16W
R303 100 1/16W
R321
10K 1/16W
D305
BAV70
1
2 3