AOC 786ls User manual

SERVICE MANUAL
17"LCD Monitor
786LS

1
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,
MANUFACTURE DATA : Aug 28 2002
REVISE: Mar 17 2003

2
TABLE OF CONTENTS
PAGE
1. SPECIFICATIONS .................................................................................................... 3
1-1 GENERAL SPECIFICATIONS ...................................................….............. 3
1-2 LCD MONITOR DESCRIPTION .................................................................. 3
1-3 INTERFACE CONNECTOR .................................................................……. 3
2. PRECAUTION AND NOTICES ................................................................................ 5
2-1 ASSEMBLY PRECAUTION ......................................................................... 5
2-2 OPERATIONG PRECAUTION ..................................................................... 5
2-3 STORAGE PRECAUTION …........................................................................ 5
2-4 HIGH VOLTAGE WARNING ....................................................................... 5
3. OPERATING INSTRUCTIONS ................................................................................ 6
4. ADJUSTMENT .......................................................................................................... 7
4-1 ADJUSTMENT CONDITIONS AND PRECAUTIONS ............................... 7
4-2 ADJUSTMENTS METHOD .& DESCRIPTION.....................…………….. 7-8
4-3 FRONT PANEL CONTROL KNOBS ............................................................ 9
5. CIRCUIT & SOFTWARE DESCRIPTION .............,…………………………….... 10
5-1 SPECIAL FUNCTION WITH PRESS KEY ………………………………. 10
5-2 CIRCUIT FUNCTION DESCRIPTION………………………….……….. 10-11
5-3 SOFTWARE FLOW CHART……………………………………………… 12
6. A). INTERFACE-BOARD TROUBLE-SHOOTING CHART .......…………..... 14-21
B). INVERTER –MODULE SPEC &TROUBLE SHOOTING CHART………. 22-25
7. MECHANICAL OF CABINET FRONT DIS-ASSEMBLY...................................... 26
8. SVC_BOM LISTING FOR LGE PART NO ………………………………............. 27-28
9. POWER SYSTEM AND CONSUMPTION CURRENT............................................ 29
10. PCB LAYOUT .....................................................................………………………... 30
11. MAINBOARD SCHEMATIC DIAGRAM ….............................….......…......... 31-36

3
1. SPECIFICATIONS FOR LCD MONITOR
1-1 General specifications
1. LCD-Panel :
Active display area 17 inches diagonal
Pixel pitch 0.264 mm x0.264 mm
Pixel format 1280 x1024 RGB vertical stripe arrangement
2. Display Color :
6-bit, 16.2 million colors
3. External Controls :
Power On/Off, Menu-key, Auto key, Left key, Right key
OSD menu Controls
Contras , Brightness, Auto Center, Focus, Clock , H/V-position , DOS mode select, R/G/B,
Color-(7200K,6500K), Languages, Reset
4. Input Video Signal :
Analog-signal 0.7Vpp
Video signal termination impedance 75 OHM
5. Scanning Frequencies :
Horizontal: 30 KHz - 83 KHz
Vertical: 55 Hz – 75 Hz
Pixel clock: 135 MHz
6. Factory Preset Timing : 17
User Timings : 13
Input signal tolerance : H tolerance ±1 K, V tolerance ±0.5 Hz
7. Input Power Source :
Switching Mode Power Supply
AC 100 – 240 V, 50/60 Hz Universal Type
8. Operating Temperature : 5°C - 40°C Ambient
Non-operating Temperature : 5°C - 40°C
9. Humidity :
Operating : 10% to 85% RH (non-condensing)
Non Operating : 5% to 85%RH (38.7℃maximum wet bulb temperature)
10. Weight : 7.6 kg
11. External Connection : 15Pin D-type Connector, AC power-Cord
12. View Angle : x-axis right/left = 70, y-axis up/down = 45 ,65
13. Outside dimension : Width x Height xThickness = 407x434 x173 mm
14. Plug and Play : VESA DDC1/DDC2B
15. Power saving : VESA DPMS

4
LCD MONITOR DESCRIPTION
The LCD MONITOR will contain an main board, an Inverter module, keyboard, External Adapter which house
the flat panel control logic, brightness control logic, DDC and DC-DC conversion
The Inverter module will drive the backlight of panel .
The Adapter will provides the 12V DC-power 4.16 Amp to Main-board,and Inverter module .
Monitor Block Diagram
1-2 Interface Connectors
(A) AC-Power Cable
(B) Video Signal Connectors and Cable
(C) External Adapter
Inverter Flat Panel and
CCFL backlight
Main Board or Interface Board
Keyboard
RS232 Connector
For white balance
adjustment in
factory mode
ADAPTER HOST Computer
CCFT Drive.
AC-IN
100v-240v Video signal, DDC

5
2. PRECAUTIONS AND NOTICES
2-1 ASSEMBLY PRECAUTION
(1) Please do not press or scratch LCD panel surface with anything hard. And do not soil LCD panel surface by
touching with bare hands ( Polarizer film, surface of LCD panel is easy to be flawed)
In the LCD panel, the gap between two glass plates is kept perfectly even to maintain display characteristic
and reliability. If this panel is subject to hard pressing, the following occurs :
(a) Uniform color (b) Orientation of liquid crystal becomes disorder
(2) Please wipe out LCD panel surface with absorbent cotton or soft cloth in case of it being soiled.
(3) Please wipe out drops of adhesive like saliva and water in LCD panel surface immediately.
They might damage to cause panel surface variation and color change.
(4) Do not apply any strong mechanical shock to the LCD panel.
2-2 OPERATING PRECAUTIONS
(1) Please be sure to unplug the power cord before remove the back-cover. (be sure the power is turn-off)
(2) Please do not change variable resistance settings in MAIN-BOARD, they are adjusted to the most suitable
value. If they are changed, it might happen LUMINANCE does not satisfy the white balance spec.
(3) Please consider that LCD backlight takes longer time to become stable of radiation characteristic in low
temperature than in room temperature.
(4) Please pay attention to displaying the same pattern for very long-time. Image might stick on LCD.
2-3 STORAGE PRECAUTIONS
(1) When you store LCD for a long time, it is recommended to keep the temperature between 5℃-40℃
without the exposure of sunlight and to keep the humidity less than 85% RH.
(2) Please do not leave the LCD in the environment of high humidity and high temperature such as 60℃
90%RH.
(3) Please do not leave the LCD in the environment of low temperature; below -15℃.
2-4 HIGH VOLTAGE WARNING
The high voltage was only generated by INVERTER module, if carelessly contacted the transformer on this
module, can cause a serious shock. (the lamp voltage after stable around 600V, with lamp current around 6.5mA,
and the lamp starting voltage was around 1650V, at Ta=25℃)

6
3. OPERATING INSTRUCTIONS
This procedure gives you instructions for installing and using the LCD monitor display.
1. Position the display on the desired operation and plug–in the power cord into External Adapter AC outlet.
Three-wire power cord must be shielded and is provided as a safety precaution as it connects the chassis
and cabinet to the electrical conduct ground. If the AC outlet in your location does not have provisions for
the grounded type plug, the installer should attach the proper adapter to ensure a safe ground potential.
2. Connect the 15-pin color display shielded signal cable to your signal system device and lock both screws
on the connector to ensure firm grounding. The connector information is as follow:
15 - Pin Color Display Signal Cable
PIN NO. DESCRIPTION PIN NO. DESCRIPTION
1. RED 9. 5V power from VGA-card
2. GREEN 10. GND
3. BLUE 11. SYNC. GND
4. GND 12. SDA
5. GND 13. HORIZ. SYNC
6. GND-R 14. VERT. SYNC
7. GND-G 15. SCL
8. GND-B
3. Apply power to the display by turning the power switch to the "ON" position and allow about thirty
seconds for Panel warm-up. The Power-On indicator lights when the display is on.
4. With proper signals feed to the display, a pattern or data should appear on the screen, adjust the brightness
and contrast to the most pleasing display, or press auto-key to get the best picture-quality.
5. This monitor has power saving function following the VESA DPMS. Be sure to connect the signal cable to
the PC.
6. If your LCD monitor requires service, it must be returned with the power cord & Adapter.
1
6
11 15
5
10

7
4. ADJUSTMENT
4-1 ADJUSTMENT CONDITIONS AND PRECAUTIONS
Adjustments should be undertaken only on following function : Contras , Brightness, Black level,
Phase, Clock , H/V-position , Languages, Color-(7200,6500,User), Auto level, OSD-position, Languages,
Reset
4-2 ADJUSTMENT METHOD
Press MENU button to activate OSD Menu or make a confirmation on desired function, Press Left/Right button to
select the function or done the adjustment.
1. White-Balance, Luminance adjustment
Approximately 30 minutes should be allowed for warm up before proceeding white balance
adjustment.
Before started adjust white balance ,please setting the Chroma-7120 MEM. Channel 1 to 7200 color and
MEM. channel 2 to 6500 color, ( our 7200 parameter is x = 302 ±20, y = 319 ±20, Y = 200 ±20cd/m2
and 6500 parameter is x = 313 ±20, y = 329 ±20, Y = 200 ±20 cd/m2)
How to setting MEM.channel you can reference to chroma 7120 user guide or simple use “ SC” key and
“ NEXT” key to modify x,yY value and use “ID” key to modify the TEXT description
Following is the procedure to do white-balance adjust
Press MENU button during 1 seconds along with plug in the DC-power cord will activate the factory mode,
and the OSD screen will located at left top of panel.
I. Bias (Low luminance) adjustment :
1. Press “ AUTO” button , and wait for message “ Pass”
2. Set the contrast on OSD window to the value=45 , color (user )R,G,B set to “50”
3. adjust the brightness on OSD until chroma 7120 measurement reach the value Y=240 cd/m2±10
cd/m2

8
II. Gain adjustment :
a. adjust 7200 color-temperature
1. Set the Contrast of OSD function to 45 and Adjust Brightness to chroma 7120 Y=240 ±5cd/m2
2. Switch the chroma-7120 to RGB-mode (with press “MODE” button )
3. Switch the MEM.channel to Channel 01 ( with up or down arrow on chroma 7120 )
4. The lcd-indicator on chroma 7120 will show x = 302 ±10, y = 319 ±10, Y = 200 ±5 cd/m2
5. Adjust the Color(user)Mode: RED on OSD window, until chroma 7120 indicator reached the value
R=100
6. Adjust the Color(user)Mode: GREEN on OSD window, until chroma 7120 indicator reached the value
G=100
7. Adjust the Color(user)Mode: BLUE on OSD window, until chroma 7120 indicator reached the value
B=100
8. repeat above procedure ( item 5,6,7) until chroma 7120 RGB value meet the torlence =100±2
9. switch the chroma-7120 to xyY mode With press “MODE” button
10. Press Color (7800) on OSD window to save the adjustment result
b. adjust 6500 color-temperature
1 Set the Contrast of OSD function to 45 and Adjust Brightness to chroma 7120 Y=240 ±5cd/m2
2 Switch the chroma-7120 to RGB-mode (with press “MODE” button )
3 switch the MEM.channel to Channel 02 ( with up or down arrow on chroma 7120 )
4 The lcd-indicator on chroma 7120 will show x = 313 ±10, y = 329 ±10, Y = 200 ±5cd/m2
5 Adjust the Color(user)Mode: RED on OSD window, until chroma 7120 indicator reached the value
R=100
6 Adjust the Color(user)Mode: GREEN on OSD window, until chroma 7120 indicator reached the
value G=100
7 Adjust the Color(user)Mode: BLUE on OSD window, until chroma 7120 indicator reached the value
B=100
8 repeat above procedure ( item 5,6,7) until chroma 7120 RGB value meet the tolence =100±2
9 switch the chroma-7120 to xyY mode With press “MODE” button
10 Press Color(6500) on OSD window to save the adjustment result
Turn the POWER-button off to on to quit from factory mode ( in USER-mode, the OSD window location
was placed at middle of screen)

9
2. Clock adjustment
Set the Chroma at pattern 63 (cross-talk pattern) or WIN98/95 shut-down mode (dot-pattern).
Adjust until the vertical-Stripe-shadow as wide as possible or no visible.
This function is adjust the PLL divider of ADC to generate an accurate pixel clock
Example : Hsyn = 31.5KHz Pixel freq. = 25.175MHz (from VESA spec)
The Divider number is (N) = (Pixel freq. x 1000)/Hsyn
From this formula, we get the Divider number, if we fill this number in ADC register (divider register), the
PLL of ADC will generate a clock which have same period with above Pixel freq.(25.175MHz) the
accuracy of this clock will effect the size of screen.(this clock was called PIXEL-CLOCK)
3. Focus adjustment
Set the Chroma at pattern 63 (cross talk pattern) or WIN98/95 shut down mode (dot-pattern).
Adjust the horizontal interference as less as possible
This function is adjust the phase shift of PIXEL-CLOCK to acquire the right pixel data .
If the relationship of pixel data and pixel clock not so match, we will see the horizontal interference on
screen ,we only find this phenomena in crosstalk pattern or dot pattern , other pattern the affect is very light
4. H/V-Position adjustment
Set the Chroma to pattern 1 (crosshatch pattern) or WIN98/95 full-white pattern confirm above item 2 & 3
functions (clock & focus) was done well, if that 2 functions failed, the H/V position will be failed too.
Adjust the four edge until all four-edges are visible at the edge of screen.
5. LANGUAGE function
There have 5 language for selection, press “MENU” to selected and confirm , press “ LEFT” or “ RIGHT”
to change the kind of language ( English , Deutch , Francais, Espanol, Italian)
6. Reset function
Clear each old status of auto-configuration and re-do auto-configuration ( for all mode)
This function also recall 7200 color-temperature , if the monitor status was in “ Factory-mode” this reset
function will clear Power-on counter ( backlight counter) too.
7. OSD-LOCK function
Press Left & Right key during switching on the monitor, the access to the OSD is locked, user only has
access to “ Contrast, Brightness, Auto-key “.
If the operator pressed the Left & Right during switching on the monitor again , the OSD is unlocked.
4-3 FRONT PANEL CONTROL KNOBS
Power button : Press to switch on or switch off the monitor.
Auto button : to perform the automatic adjustment from CLOCK, FOCUS, H/V POSITION, but no affect the
color-temperature
Left/Right button : select function or do an adjustment.
MENU button : to activate the OSD window or to confirm the desired function

10
5. CIRCUIT-DESCRIPTION
5-1 SPECIAL FUNCTION WITH PRESS-KEY
A). press Menu button during 2 seconds along with plug-in the DC Power cord:
That operation will set the monitor into “Factory- mode”, in Factory mode we can do the White balance
adjustment with RS232
In Factory mode, OSD-screen will locate in left top of screen.
Press POWER-button off to on once will quit from factory mode and back to user-mode.
B). Press both Left & Right button along with Power button off to on once will activate the OSD-LOCK
function, repeat this procedure will disable OSD-LOCK
In OSD-LOCK function, all OSD function will be lock , except Contrast and Brightness
OSD-INDEX EXPLANATION
1. CABLE NOT CONNECTED: Signal-cable not connected.
2. INPUT NOT SUPPORT:
a. INPUT frequency out of range: H > 83kHz, v > 75Hz or H < 28kHz, v < 55Hz
b. INPUT frequency out of VESA-spec. (out of tolerance too far)
5-2 CIRCUIT FUNCTION DESCRIPTION 1. U200,GMZAN2 ( all-in-one chip solution
for ADC, OSD, scalar and interpolation) :
USE for computer graphics images to convert analog RGB data to digital data with interpolation process,
zooming, generated the OSD font , perform overlay function and generate drive-timing for LCD-PANEL.
2. U302,89C51RD2 (PHILIPS- MCU, type
8052 series with 64k Rom-size and 512 byte
ram) :
Use for calculate frequency, pixel-dot , detect change mode, rs232-communication, power-consumption
control, OSD-index warning , …etc.
3. U203,24LC21 (MicroChip IC) :
EEPROM type, 1K ROM-SIZE, for saving DDC-CONTENT.
4. U300,24C16 (ATMEL IC) :
EEPROM type, 16K ROM-SIZE, for saving AUTO-config data, White-balance data, and Power-key status
and Backlight-counter data.
5. U304,LM2569S( NS brand switching
regulator 12V to 5V with 3A load current) .
6. U305,AIC 1084-33CM (AIC brand linear
regulator 5V to 3.3V)
7. U905,RT9164(Linear regulator 5V to 2.5V)
8. U600,U601,LVDS ( use NOVATEK NT7181F)
Convert the TTL signal to LVDS signal , the advantage of LVDS signal is : the wire can be lengthen and
eliminate wire number , low EMI .LVDS signal is high frequency but low voltage, only 0.35 VPP ,the
frequency is seven times higher than TTL
9. U401, 74F14D(Schmitt triggger)
The 74F14 contains six logic inverters which accept standard TTL input signals and provide standard TTL
Output levels

11
MODULE-TPYE COMPONENT:
1. ADAPTER : CONVERSION-module to convert AC 110V-240V to 12VDC, with 4.16 AMP
2. INVERTER : CONVERSION-module to convert DC 12V to High-Voltage around 1650V, with frequency
30K-80Khz, 5.6mA-13mA
GMZAN2 (U200)
LVDS chip (U601,
U602)
Panel-Power Control
(U202)
MCU ( U302 )
Data Digital RGB
Panel Control Signal:
Phs, Pvs,
PclkA/B
,
Pdis
p
e
Panel Power 5V
Communication signal:
Hclk,Hfs,Hdata0
Input analog RGB &
H,V,& ddc signal &
Rs232 communicatio
n
Oscillator 50 mhz
Cr
y
stal 20 MHz
DDC-chi
p
PANEL
Main-board Block diagram
INVERTER module
Keyboard module
EXTERNAL
-
ADAPTER
DC 12V 4.16Amp

12
5-3 SOFTWARE FLOW CHART
I. Power-On Subroutine CHART
OK
Check White-balance data(6500 & 7200) same with the backup
data ?
Check POC( backlight counter) data same with the backup data ?
IF not same, overwrite the data with backup value.
Initial GMZAN2
Y
es
POWER-ON START
Initial MCU I/O, Interrupt vector & Ram
Initial 1.POC (backlight counter)
2. Clr all mode value
Y
es
Check if in Factory mode?(when power-on,press the
MENU Button will be in FACTORY mode) SET factor
y
mode fla
g
Check Previous power-switch status from Eeprom, & other system status
MAIN-SUBROTINE LOOP
No
Check Eeprom is empty ?
Clear factor
y
mode fla
g
No

13
II. MAIN SUBROTINE LOOP
)
Main loop start
Process Power-saving status ( according to below flow-chart result)
Check GMZAN2 IFM status .is change or not.
And check Signal cable status ( cable not connected or not )
** IFM is the register which measured the HSYN & Vsyn status
Is current system status in Power-saving ?
Yes, IFM have change Wake-up GMZAN2
(because GMZAN2 was in
partial sleeping state)
Y
es
Check the IFM result is in the standard
Mode table ?
No
Check the IFM result is in the user mode
table ?
Out of range ( input not support) be
confirm
Set mode index & parameter
Set change mode flag
No
No
Y
es
Y
es
confirm the frequency ( Hsyn or Vsyn) from IFM already
been changed ? ( check the change mode flag)
Process ( turn off OSD , setting GMZAN2according to
above parameter, set LED status, set backlight status)
Check Auto-config mode flag already been set?
No
Do Auto-config
automatically
Read Key status and Process on OSD-screen
Check Factory mode flag= 1
No
Y
es
,
fr
eq
h
ad
bee
n
c
h
a
n
ge
Monitoring the time-out of osd status ( if no key input persist for
10 sec , the osd time-out counter will trigger )
No
if the RS232 buffer is full,
process the command( while
adjust white-balance in factory
mode)
Y
es
No
Y
es

14
6 A). INTERFACE-BOARD TROUBLE-SHOOTING CHART
*Use the PC Win 98 white pattern, with some icon on it, and Change the Resolution to 640x480 60 Hz / 31 KHz
**NOTICE : The free-running freq. of our system is 48 KHz / 60 Hz, so we recommend to use another resolution
to do trouble shooting, this trouble shooting is proceed with 640x480 @60Hz 31Khz
I. NO SCREEN APPEAR
Note: 1. if Replace “MAIN-BOARD” , Please re-do “DDC-content” programmed & “WHITE-Balance”.
2. if Replace “ INVERTER” only, Please re-do “ WHITE-Balance”
Disconnected the Signal cable( Loose the
Signal cable ),Is the screen show “Cable Not
Connected” ?
Connected the Signal cable again,
Check LED status.
N
o
,
nothin
g
is sho
w
Y
es,
th
e
r
e
ha
ve
OS
D
s
h
ow
Connected the Signal cable again,
Check LED status.
Check the Wire-Harness from CN603
was tight enough?,
check the Wire connection to panel side too
OK,Wire tight enough
Led Green
Check Panel-Power Circuit Block
Check U200 Data-output Block
OK,Panel Power OK
Replace Inverter and Check
Inverter control relative circuit
Re-do White balance adjust
OK, U200 data OK
Check Power switch is in Power-on
status , and check if Power switch had
been stuck ?
Measured RGB (r200,r201,r202) H,V Input at U401
p
in 9
,
4
,
was there have si
g
nal ?
Measured Oscillator Bloc
k
Oscillator U201 & Crystal X300
Check communication pin between U200 &
MCU pin 2,6,7. , is it have transition?
Led Oran
g
e
Replace U200 (Gmzan2)
OK
,
Ke
y
board no stuc
k
OK
,
in
p
ut Normal
OK
,
clock normal
OK
,
Mcu have transition
Replace U302 (MCU)
& check Reset pin 10
must be change from High to
low when first AC power plug-
in
N
G
,
no transition
Led oran
g
e
OK OK
R
ep
la
ce
M
CU
Led Green
Measured Input DC-voltage ( J1)= 12 V?
Measured U305 AIC 1084 pin 2 = 3.3V?
Measured U904 LT1117 pin 2= 3.3V?
Measured U905 RT9164 pin 2=2.5v
Yes
,
all DC level exist
Check Correspondent component.
Is there any shortage or cold solder?
DC-Power Part
Check Correspondent
component short/open
( Protection Diode )
and Signal cable
bad ?
NG

15
PANEL-POWER CIRCUIT
INVERTER Control Relative Circuit
OSCILLATOR BLOCK
U200-DATA OUTPUT
OK,R225 have response
check R225 should have response from 0V to 5V
When we switch the power switch from on to of
f
Check the PPWR panel power relative circuit,
R223,R224, Q200,U202(pin 5,6,7,8)
In normal operation, when LED =green, R223
should =0 v,
If PPWR no-response when the power switch
Turn on and turn off, replace the U200-GMZAN2
NG
Measured the U202 pin 5,6,7,8= 5 V? Replace U202 ( Nmos, SI9953)
N
G
,
no Volta
g
e
OK
Replace INVERTER to new-one, and
Check the screen is normal ??
Measured the inveter connector CN303
Pin 1,2=12V, pin 3 on/off control=5V (on
)
YE
S,
st
ill n
o
sc
r
een
Check the Bklt-On relative circuit, R315, Q304, R311,
In normal operation, when LED =green,
R315 Bklt-On should =0 v,
If Bklt-On no-response when the power switch turn on-off,
Replace the MCU
NG
O
K
,&
R
e
-
do
w
hit
e
b
alan
ce
OK
Measured U201 Oscillator output R215= 50MhZ ? Replace Oscillator U201
NG,
n
o
t
r
a
n
s
i
t
i
on
O
K
,
ha
s
tran
s
iti
on
Measured X300 Crystal output R340= 20MhZ ? Replace Crystal X300
NG,
n
o
t
r
a
n
s
i
t
i
on
OK
Measured PCLK(L207,R603)
PVS,PHS,PDISPE (pin 73,74,43 from U200 )
Is there have any transition?
Pclk around 47MHz to 57MHZ ,
PVS=60.09Hz , PHS around 67 KHz ??(refer to
input signal=640x480@60 Hz 31k, and LED is
green)
Replace GMZAN2 (U200) or replace
MAINBOARD.
NG
,
n
o
tran
s
iti
on
OK
If Main Board being replace , please
do the DDC – content reprogrammed
Check U202 pin 1,3= 5V
Ye
s
Check U304 relative circuit.(D300,L906..)
Check JP202 shortage
NG
NG

16
II (a) THE SCREEN is Abnormal , stuck at white screen, OSD window can’t appear, but
keyboard & LED was normal operation.
At general, this symptom is cause by missing panel data or panel power, so we must check our
wire-harness which connected to panel or the panel power controller (U202)
Check if the Wire harness from CN603 loose?
Check the wire on both Panel-side and Main board side.
Check the Panel-Power circuit as above (page 16)
U202 pin 5,6,7,8 ,must be 5V
Yes, tight enough
Yes, Voltage normal
Check the LVDS-Power L601,L602,L603,L604,L900= 3.3V ?
Check the both U601 & U602 LVDS-Input pin 31= 45mhz –
65mhz, and pin 27 = Vsyn freq, pin 28 = 45khz- 65 khz
Yes, Voltage normal
Yes, Frequency normal
Replace both LVDS chip ( U601 & U602)
Tighten it.
NG
Check U904,which convert the 5V to
3.3V
Check U200 DATA-OUPUT block as
above ( page 16)
NG
Check OSCILLATOR Block as
above ( page 16)
N
G, no data outpu
t
Replace U302 MCU and check it RESET
pin 10 ,must be turn high to low when first
AC
p
owe
r
-o
n
OK, all clock is normal
Replace U200 GMZAN2
OK
,
reset is normal
Check U200 DATA-OUTPUT block again
N
G
,
still no data out
NG

17
II. (b)The screen had the Vertical Straight Line, might be stuck in Red, Green, Blue
That symptom is cause by bad Panel issue ( might be the Source IC from Panel is cold solder or
open loop ) so REPLACE THE PANEL TO NEW ONE.
KEYBOARD BLOCK check
OK
Check U302 pin 38 (LED green) will have
transition from hi to low or low to hi when we
press the power key??
Press power key and check U302 pin 43
= low (0V) ?
OK
Check main board R303 shortage?
Replace Tact-switch SW105 at keyboard if still
no work replace U302 MCU at main-board and
check MCU relative reset circuit, and crystal
OK
Check U302 MCU pin 43,42,41,40,39 at
High state(5V)? without press any key Mechanical was stuck, Check !
N
G
NG
If still no Led green indicator, check Q102,
R106 & LED at keyboard !! cold solder or bad
N
G, MCU no response
Check U302 pin 20= 20MHz ? and pin 44
(VDD)=5V ? and pin 10 (reset)=0V ? at normal
condition
If one of this item was NG, check the relative
circuit
NG
Without press key and change mode, Check U302
pin 16,17(sda,scl)= hi 5V ? or keep transition ?
OK
Check U300 eeprom 24LC16 relative circuit,
check U300 pin 7 = low?
Keep transition, that means eeprom no response
Check JP302 is
connect ?
NG
NG
Check U300 pin 8
(vdd)= 5V, and check
R300
,
R301 cold solde
r
OK
Replace eeprom
Replace U302 MCU
O
K
,
n
o
k
eep
tran
s
iti
on

18
POWER-BLOCK check
**Note : the Waveform of U304 pin 2 can determined the power situation
1. stable rectangle waveform with equal duty, freq around 150K-158KHz
that means all power of this interface board is in normal operation
,and all status of 5V & 3.3V is working well
2. unstable or uneven rectangle waveform without same duty, that means ABNORMAL operation was
happened, check 3.3V or 5V ,if short-circuit or bad component
3. rectangle waveform with large spike & harmonic pulse on front side , means all 3.3v is no load, U200
Gmzan2 was shut-down, and only U302 MCU still working , that means the monitor is in power saving
status , all power system is working well .
OK
Check U304 pin 2 is a stable rectangle wave?
Around 150k-158kHz stable rectangle wave
with equal duty without any spike or harmonic
pulse?
OK
N
G, with
harmonic
p
ulse
Check U304 pin 2 is a unstable rectangle wave ?
The interface board power is good
Measure input power at U304 LM2596 pin 1=
12V ? Check ADAPTER and connector if loose?
N
G
N
G
Check all 3.3V & 5V power, there is
short circuit or bad component was
happened
OK
,
unstable wave
The interface board is in power-
saving state, press power key to wake
up & check your signal input

19
III.ALL SCREEN HAS INTERFERENCES OR NOISE, CAN’T BE FIXED BY AUTO KEY
** NOTE: There is so many kind of interferences, 1). One is cause by some VGA-CARD that not meet VESA spec or
power grounding too bad that influence our circuit
2).other is cause by external interferences, move the monitor far from electronic equipment.( rarely
happened)
Use DOT-pattern, or win98/99 shut-down
mode pattern, press “AUTO” key, was the
interferences disappear ??
Adjust “FOCUS” step by step, until the
horizontal interferences disappear
Does your signal-cable have an additional
cable for extension ??
END
END
Put away the additional cable
May be the additional cable grounding is
not quite well
Does your noise only exist in one mode only?
(ex: only at 1280x1024 @ 75 Hz, other is normal)
OK
OK
Yes, has extension
NG,
int
e
rf
e
r
e
n
ces
s
till
e
xi
st
NG
N
Oadditional extension cable
That was cause by you VGA-CARD setting, your VGA
card timing back porch / front porch exceed vesa timing
too far, for some new AGP-VGA-CARD such situation
always happened
So in your control-panel icon ,select monitor ,setting ,
advance ,screen-adjust ,at
Size icon, increase step by step slowly, press “”AUTO”
key every step you increase the SIZE . repeat the
procedure( increase/decrease SIZE one-step and press
AUTO) until the interferences disappear, press “APPLY”
to save in your VGA
Yes, only happened on one mode
Change the Signal-cable to new-one or
Try other brand VGA-CARD
(make sure just only that brand VGA-
CARD has this problem ,contact RD-
Taipei)
NO,
all m
ode