LG LCD 782LS User manual

COLOR MONITOR
SERVICE MANUAL
Website:http://biz.LGservice.com
E-mail:http://www.LGEservice.com/techsup.html
CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
CHASSIS NO. : CL-29
FACTORY MODEL: LB782G
MODEL: LCD 782LS (LB782G-GD)
*( ) ID LABEL MODEL No.

CONTENTS
- 2 -
SPECIFICATIONS ................................................... 2
PRECAUTIONS ....................................................... 3
TIMING CHART ....................................................... 4
OPERATING INSTRUCTIONS ................................ 5
WIRING DIAGRAM ................................................. 6
DISASSEMBLY ....................................................... 7
BLOCK DIAGRAM AND DESCRIPTION ................ 8
ADJUSTMENT ....................................................... 11
TROUBLESHOOTING GUIDE .............................. 12
PRINTED CIRCUIT BOARD................................... 17
EXPLODED VIEW...................................................19
REPLACEMENT PARTS LIST ...............................21
PIN CONFIGURATION............................................25
SCHEMATIC DIAGRAM......................................... 26
SPECIFICATIONS
1. LCD CHARACTERISTICS
Type : TFT Color LCD Module
Size : 17.0 inch (43.2 cm diagonal)
Pixel Pitch : 0.264(H) x 0.264(V)
Elecctrical Interface : LVDS
Color Depth : 6-bits+FRC, 16,194,277 colors
Size (mm) : 383.5(H) x 306(V) x 21.0(D) Typ
Surface Treatment : Anti-Glare, Hard Coating (3H)
Operating Mode : Normally white
Backlight Unit : Four-CCFL (Cold Cathode
Fluorescent Lamp)
2. OPTICAL CHARACTERISTICS
2-1. Viewing Angle by Contrast Ratio
≥ 10
Left : 70° Typ. , Right : -70° Typ.
Top : 45° Typ. , Bottom : -65° Typ.
2-2. Luminance : 200 (min.) 250 (typ.)
2-3. Contrast Ratio : 250 (min) 400 (typ.)
3. SIGNAL (Refer to the Timing Chart)
3-1. Sync Signal
• Type : Separate TTL (Positive/Negative)
3-2. Video Input Signal
1) Type : R, G, B Analog
2) Voltage Level : 0~0.714 V
a) Color 0, 0 : 0 Vp-p
b) Color 7, 0 : 0.467 Vp-p
c) Color 15, 0 : 0.714 Vp-p
3) Input Impedance : 75 Ω
3-3. Operating Frequency
Horizontal : 30 ~ 83 kHz
Vertical : 56 ~ 75 Hz
4. POWER SUPPLY
4-1. Power
AC 100~240V, 50/60Hz , 1.0A
4-2. Power Consumption
5. ENVIRONMENT
5-1. Operating Temperature: 10°C ~ 35°C (50°F ~ 95°F)
(Ambient)
5-2. Relative Humidity : 5% ~ 95%
(Non-condensing)
6. DIMENSIONS (with TILT/SWIVEL)
Width : 419 mm (16.49'')
Depth : 205 mm (8.07'')
Height : 410 mm (16.14'')
7. WEIGHT (with TILT/SWIVEL)
Net. Weight : 6.8 kg (14.99 lbs)
Gross Weight : 8.4 kg (18.52 lbs)
MODE
POWER ON (NORMAL)
STAND-BY
SUSPEND
OFF
POWER OFF
H/V SYNC
ON/ON
OFF/ON
ON/OFF
OFF/OFF
-
POWER CONSUMPTION
less than 45 W
less than 3 W
less than 3 W
less than 3 W
less than 3 W
LED COLOR
GREEN
AMBER
AMBER
AMBER
OFF
VIDEO
ACTIVE
OFF
OFF
OFF
-

- 3 -
WARNING FOR THE SAFETY-RELATED COMPONENT.
• There are some special components used in LCD
monitor that are important for safety. These parts are
marked on the schematic diagram and the
replacement parts list. It is essential that these critical
parts should be replaced with the manufacturer’s
specified parts to prevent electric shock, fire or other
hazard.
• Do not modify original design without obtaining written
permission from manufacturer or you will void the
original parts and labor guarantee.
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 are
grounded through wrist band.
• Do not leave the module in high temperature and in
areas of high humidity for a long time.
• The module not be exposed to the direct sunlight.
• Avoid contact with water as it may a short circuit within
the module.
• If the surface of panel become dirty, please wipe it off
with a softmaterial. (Cleaning with a dirty or rough cloth
may damage the panel.)
WARNING
BE CAREFUL ELECTRIC SHOCK !
• If you want to replace with the new backlight (CCFL) or
inverter circuit, must disconnect the AC adapter
because high voltage appears at inverter circuit about
650Vrms.
• Handle with care wires or connectors of the inverter
circuit. If the wires are pressed cause short and may
burn or take fire.
PRECAUTION
CAUTION
Please use only a plastic screwdriver to protect yourself
from shock hazard during service operation.

TIMING CHART
- 4 -
VIDEO
SYNC
B
D
CFE
A
H + 31.469 800 640 16 96 48
V–70.09 449 350 37 2 60
H–31.469 800 640 16 96 48
V–59.94 525 480 10 2 33
H–37.5 840 640 16 64 120
V–75 500 480 1 3 16
H–31.468 900 720 18 108 54
V + 70.08 449 400 12 2 35
H + 37.879 1056 800 40 128 88
V + 60.317 628 600 1 4 23
H + 46.875 1056 800 16 80 160
V + 75.0 625 600 1 3 21
H+/–49.725 1152 832 32 64 224
V+/–74.55 667 624 1 3 39
H–48.363 1344 1024 24 136 160
V–60.0 806 768 3 6 29
H–60.123 1312 1024 16 96 176
V–75.029 800 768 1 3 28
H+/–68.681 1456 1152 32 128 144
V+/–75.062 915 870 3 3 39
H+/–61.805 1504 1125 18 134 200
V+/–65.96 937 900 2 4 31
H + 63.981 1688 1280 48 112 248
V + 60.02 1066 1024 1 3 38
H + 79.976 1688 1280 16 144 248
V + 75.035 1066 1024 1 3 38
Mode H/V
Sort
1
2
3
4
5
6
7
8
9
10
11
12
13
25.175
28.321
25.175
31.5
40.0
49.5
57.283
65.0
78.75
100.0
92.978
108.0
135.0
640x350
70Hz
640x480
60Hz
640x480
75Hz
720x400
70Hz
800x600
60Hz
800x600
75Hz
832x624
75Hz
1024x768
60Hz
1024x768
75Hz
1152x870
75Hz
1152x900
65Hz
1280x1024
60Hz
1280x1024
75Hz
<< Dot Clock (MHz), Horizontal Frequency (kHz), Vertical Frequency (Hz), Horizontal etc... (µs), Vertical etc... (ms) >>
Sync
Polarity
Frequency
DOT
Clock
Total Period
(E) Video Active
Time (A) Sync Duration (D) Back Porch
(F)
Front Porch
(C)
Resolution

- 5 -
1. MENU Button
Use this button to enter or exit the on screen display.
2.
Use these buttons to choose or adjust items in the on
screen display
3. AUTO Button
Use this button to enter a selection in the on screen
display.
4.
OPERATING INSTRUCTIONS
Front Control Panel
FRONT VIEW REAR VIEW
D
AUDIO
DC OUT
D-Sub Signal Port
Power Connector
AUDIO DC OUT
Power (DPMS) Indicator
Power ON/OFF Button
Button
AUTO Button Power Button
MENU Button
Power Indicator
SET Button
Button
<Shortcut Keys>
•Brightness and Contrast can be
adjusted directly without entering the
On Screen Display (OSD) system.
Touch the buttons to adjust
the settings and then the OSD button
to save all changes. The Brightness
and Contrast functions are also
available in the On Screen Display
(OSD) menu.
100
100
* AUTO adjustment function
TO the AUTO button before
using OSD menu. This button is
for the automatic adjustment of the screen position, clock
and phase.
Note: Some signal from some graphics boards may not
function properly. If the results are unsatisfactory, adjust
your monitor’s Position, Clock and Phase manually.
PROCESSING
AUTO CONFIGURATION
MENU, Button
CONTROLS LOCKED
CONTROLS UNLOCKED
Press the hold the MENU button and
button for 3 seconds: the message
“CONTROLS LOCKED”appears.
You can unlock the OSD controls
at any time by pushing the MENU,
button for 3 seconds:
the message “CONTROLS UNLOCKED”will appear.

- 6 -
WIRING DIAGRAM
J801
PG4
J702
CN1 CN3
J1
CN2
Connector Ass’y P/No.:
6631T11012W
Connector Ass’y P/No.:
6631T25008R
Connector Ass’y P/No.:
6631T20015A
Connector Ass’y P/No.:
6631T20008P
J706 J710

- 7 -
DISASSEMBLY
(a)
(a)
(a)
(a)
1) Set the Monitor face downward.
2) Remove four screws (a).
BACK COVER REMOVAL
3) Set the Monitor as picture.
4) Release the bottom & side latch.
7) Release the center positon latch.
5) Set the Monitor face upward.
6) Release the up side latch.
8) Set the Monitor face downward.
9) Remove the Back cover.
※Caution: When you open the Back cover, Be careful! Dont stress the Control Board Connector.
(b) Latch Point
(b) (b)
(b)
(b)
(b)
(b)
(b)
(b) (b) (b)

BLOCK DIAGRAM
- 8 -
To Inverter
12V
BRT-CTL
Tx+/-,Hs,Vs,CLK,DEN
INV-CTL
EEPROM
(SYSTEM)
Analog
Signal
ADC
+ PLL
OSD
Scaling
GM5020
DC/DC Block
Regulator Regulator
2.5V 3.3V
MCU
LVDS Tx
POWER BOARD DDC
(EDID)
12V(Inverter)
5.0V
90-264V
12V
Module Power (5V)
DSUB
(H/V Sync)
(R,G,B)
SDA, SCL
H SYNC
AC INPUT

DESCRIPTION OF BLOCK DIAGRAM
- 9 -
1. Input signal part.
There is one input which is analog.
It comes from 15 pin D-Sub connector.
2. Pre-amp/ ADC / PLL / Video Controller.
This part amplifies the level of video signal from the analog video signal to the digital video signal using a pixel
clock.
The pixel clock for each mode is generated by the PLL.
The range of the pixel clock is from 25MHz to 135.0MHz.
The Scaler gets the video signal converted analog to digital, interpolates input to 1280 X 1024 resolution signal
and outputs 8-bit R, G, B signal to LCD module.
Especially pre-amp / ADC / Video controller are merged to one chip ‘gm5020’by Genesis.
3. Power Part.
This circuit is working of 90~260VAC(50/60Hz). The operation procedure is as follows:
1) AC Input voltage is rectified and smoothed by the bridge diodes(BD901) and the capacitor(C905).
2) The Rectified voltage(DC) is applied to the primary coil of the transformer(T901).
3) The control IC(IC901) generates switching pulse to turn on and turn off the primary coil of the
transformer(T901).
4) Depending on turn ratio of the transformer, the secondary voltages appear at the secondary coils of the
transformer(T901).
5) These secondary voltages(12V,5V) are rectified by each diodes(D903,D906) and operates other
circuit.(Inverter,Scaler…etc)
4. MICOM Part.
This part consists of EEPROM IC which stores control data, Reset IC and the Micom.
The Micom distinguishes polarity and frequency of the H/V sync are supplied from signal cable.
The controlled data of each modes is stored in EEPROM.
5. Inverter
The inverter converts from DC12V to AC 700V and operate back-light lamp of module.

BLOCK DIAGRAM
- 10 -
EMI
COMPONENTS
LINE
100 ~ 240V
INPUT RECTIFIER
AND FILTER ENERGY TRANSFER OUTPUT RECTIFIER AND FILTER
12V
5V
GND
SIGNAL
COLLENTION
PHOTO-COUPLER
ISOLATION
PWM CONTROL
CIRCUIT
HVDC 100KHz
PRIMARY SECONDARY
50 ~ 60Hz
POWER BOARD
DESCRIPTION OF BLOCK DIAGRAM
1. EMI components.
This part contains of EMI components to comply with global marketing EMI standards like FCC the circuit included
a line-filter, across line capacitor and of course the primary protection fuse.
2. Input rectifier and filter.
This part function is for transfer the input AC voltage to a DC voltage through a bridge rectifier and a bulk capacitor.
3. Energy Transfer.
This part function is transfer the primary energy to secondary through a power transformer.
4. Output rectifier and filter.
This part function is to make a pulse width modulation control and to provide the driver signal to power switch, to
adjust the duty cycle during different AC input and output loading condition to achive the dc output stablize, and also
the over power protection is also monitor by this part.
5. Photo-Coupler isolation.
This part function is to feed back the dc output changing status through a photo transistor to primary controller to
achive the stablized dc output voltage.
6. Signal collection.
This part function is to collect the any change from the dc output and feed back to the primary through photo
transistor

ADJUSTMENT
- 11 -
All adjustment are thoroughly checked and corrected
when the monitor leaves the factory, but sometimes
several minor adjustment may be required.
Adjustment should be following procedure and after
warming up for a minimum of 10 minutes.
•Alignment appliances and tools.
- IBM compatible PC
- Programmable Signal Generator.
(eg. VG-819 made by Astrodesign Co.)
- E(E)PROM with each mode data saved.
1. Adjustment Start
1) Display any pattern at any Mode.
2) Run alignment program for LB782G on the IBM
compatible PC.
3) Select EEPROM →ALL INIT command and Enter.
4) This will make all data to default state.
5) Select COMMAND →PRESET START command
and Enter.
2. Adjustment for White Balance
1) Display Black pattern at SXGA/60Hz.
2) Set External Bright to MAX position and Contrast to
80 Position.
3) Select PRESET START → BIAS CAL command
and Enter.
4) No attempt to manually adjust, BIAS data is auto-
matically adjusted and saved to the EEPROM.
5) Display Full White pattern at SXGA/60Hz.
6) Select DRIVE CAL command and Enter.
7) 9300K are automatically adjusted and
saved to the EEPROM.
8) Select PRESET EXIT command and Enter.
3. Adjustment for EDID
1) Use this procedure only when there is some
probelm on EDID data.
2) Connect the D-sub cable.
3) Select EEPROM →EDID(A) WR command and
Enter.
Figure 1. Cable Connection
D
AUDIO
DCOUT
220
IBM
Compatible PC
Video Signal
Generator
PARALLEL PORT
Power inlet (required)
Power LED
ST Switch
Power Select Switch
(110V/220V)
Control Line
Not used
RS232C
PARALLEL
V-SYNC POWER
ST
VGS MONITOR
E
E
V-Sync On/Off Switch
(Switch must be ON.)
F
F
A
A
B
B
C
C
1510
5
569
1
1
1
14
13
25
6
5V
5V
5V
4.7K
4.7K
4.7K
74LS06
74LS06
OFF ON
OFF
ON
11

- 12 -
TROUBLESHOOTING GUIDE
1. NO POWER
TROUBLE IN
BULT-IN POWER
CHECK J801
5VST VOLTAGE
(5V) ?
NO
NO POWER
(POWER INDICATOR OFF)
TROUBLE
SOMEWHERE ELSE
TROUBLE IN
BULT-IN POWER
CHECK J801
INPUT VOLTAGE
(12V) ?
NO
TROUBLE IN
U501 or X501
NO
YES
YES
YES
CHECK
U501’s PIN 6.
IS THIS PIN
OSCILLATED?

- 13 -
2. NO RASTER
TROUBLE IN
INVON PATTERN
CHECK
J702 PIN 8 (5V) ? NO
NO RASTER
TROUBLE IN
POWER ADATER
or L703, L704
CHECK
J702 PIN 1, 2, 3
(12V) ?
NO
TROUBLE IN
X501
CHECK
X501
H. PULSE ?
NO
TROUBLE IN
U201
CHECK
U201(GM5020) ? NO
TROUBLE IN
U201
NO
YES
YES
YES
YES
CHECK
L201, L202, L203
PULSE?

- 14 -
CHECK DOT CLOCK
PATTERN
NO
TROUBLE IN
U201
NO
CHECK
DVS PATTERN
NO
CHECK
DHS PATTERN
NO
YES
YES
YES
YES
YES
TROUBLE IN
LCD MODULE
CHECK
U401 PIN 8
V.PULSE?
CHECK
U401 PIN 7
V.PULSE?
CHECK
U401 PIN 10
PULSE ?
CHECK
L204
PULSE ?

- 15 -
3. NO CLOCK (CLOCK GENERATOR)
NO DOT CLOCK
TROUBLE IN
X201
CHECK
X201 24MHz ? NO
TROUBLE IN
U201
CHECK
L201
CLOCK ?
NO
YES
YES

- 16 -
4. TROUBLE IN DPM
TROUBLE IN DPM
TROUBLE IN PC
CHECK PC
PC IS NOT GOING
INTO DPM OFF MODE
NO
TROUBLE IN
X501
NO
TROUBLE IN
SIGNAL CABLE
NO
YES
YES
YES
CHECK
U501 PIN 6
WAVEFORM
(24MHz) ?
CHECK
R233, R234?
CHECK
U501 PIN 11
(0V) ?

PRINTED CIRCUIT BOARD
- 17 -
1. MAIN BOARD (Component Side)
C860
R526
L822
R809
C820
C506
U802
C819
J706
R732
J710
R707
Q705
R706
D730
R713
R705
C840
R531
C511
R529
R527
R580
R508
R511
R512
R513
R524
R525
C818
C504
C505
C507
C514
C515
R810
C408
L823
C405
C403
504030
C402
C401
1
C413
L403
ZD721
C730
R730
ZD722
C731
C729
R731
R708
R709
C703
C702
R714
R715
R716 D731
R704
D704D703
U502
C503C510
C513
1
C509
R528
R540
R523
R522
40
L401
70
60
20
10
R405
R403
R402
R401
C207
C220
C238
C257
L204
C216
C215
C214
C209
C211
C817
C738 R750 R751
Q703
R207
R205
R204
R203 L207
Q704
R208
R209
R213
C229
L206
R703
D702
L821
X501
L811
C501
R501
C522
R541
R520
R519
R518
R450
C516
R536
R537
R542
C410
C406
90 80 100
1
U401
C404
C236C232
R404
R236
C221
L201
L202
L203
C235
R206
R214
R216
R215
R211
R210
R212
U701
C265
R234
Y
C264
R233
J704
D701
ZD711 ZD703
ZD704
J801
R804
C502
10
C520
R516
R534
R535
R539
A
R543
L402
C407
RA218
RA214
RA216
C231
C258
C230
X201
P
R
T
U
V
W
C239
R235
D503
R711
R593
D504
C714
C715R712
R594 R595 R596
D801
C508
R805
R560
R562
R564
30
C519
R538
C809
C812
RA222
RA220
RA224
C219
N
M
L
K
J
H
C226
C240
C227
C548
C740
C710
L810
R561
R563
20
A
C517
R545
R544
R807
C811
C836
C835
RA204
RA202
G
F
E
D
C
B
C280
C278
C279
C228 C218
C259
C260
C261
R223
R224
R222
R225
R221
R220
U509
C845
C837
U501
C838
C531
R581
R582
U503
C834
RA208
RA206
C202 C201 C203
C234 C224 R201
R202
2019
U201
C204
C872
C873
181716151413121110987
C206
C205 C274 C276
A
C827 C826
C825
C701
C839
U801
C707
U821
MODEL:LG708G GM5020 P/N :6870T487A11
DATE :2002.04.03
R829 R830 RA212
C208
R826 R820 R819 R828 R827
RA210
C217 C222 C223 C210 C212
R831
U803
C822
C832
C833
L804
C831
C275 C272C273
U820
L805
C828
J702
C706
R702
R701
C830
C829
R817 R818 R813 R812 R815 R816 R814 C870 C871 R811
C823 C824
2. CONTROL BOARD (Component Side)
3. CONTROL BOARD (Solder Side)

- 18 -
4. POWER BOARD (Component Side)
5. POWER BOARD (Solder Side)

- 19 -
1
2
5
6
13
3
914
4
12
10
8
7
11 15
a
b
c
EXPLODED VIEW

EXPLODED VIEW PARTS LIST
- 20 -
Ref. No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
a
b
c
Part No.
3091TKL031H
6304FHD004A
3809TKL021A
3043TKK037M
4951TKS082F
6633TZA011A
4814TKK200A
3313TL7004B
6631T11012W
6871TST276A
6871TPT220A
4814TKK187A
4950TKS189A
3550TKK053A
6850TD9001A
1SZZTAT001A
332-095C
332-105F
Description
CABINET ASSEMBLY, LB782G BRAND ANALOG ONLY EXPORT
LCD(LIQUID CRYSTAL DISPLAY) HT17E11-300 HYUNDAI TFT COLOR SXGA 17 INCH LVDS
BACK COVER ASSEMBLY, LB782F 3808TKL026 PC+ABS
TILT SWIVEL ASSEMBLYLB782F . NO USB
METAL ASSEMBLY, FRAME LB782G -HYDIS MODULE
INVERTER ASSEMBLY, LG-PHILIPS NMC1804,4-LAMP AU MODULE LB782
SHIELD INVERTER LB782F
MAIN TOTAL ASSEMBLY LB782G BRAND CL-36
CONNECTOR ASSEMBLY, 30P H-H 200MM UL20276 LG708G
PWB(PCB) ASSEMBLY,SUB, LB782F CONTROL TOTAL BRAND
PWB(PCB) ASSEMBLY,POWER, LB782F POWER TOTAL BRAND NO SWITCH
SHIELD REAR LB886F
METAL REAR LB782F
COVER LB880B HINGE BRAND 18.1" LCD
CABLE,D-SUB, UL 2990-9C(7.5) DT 1870MM GRAY(85964) BRAND DM
SCREW, DRAWING, D3.0 L28.0 MSWR/FZMY LB782F
SCREW, PZP+3*12 (MSWR/FZMY)STD
SCREW, DRAWING D4.0 L10.0 MSWR/FZMW