LG 500G, s 500E Service Manual

COLOR MONIT OR

SER VICE 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.

MENU

SELECT

MODEL: StudioWorks 500E

(500EJ-AL**M)

StudioWorks 500G

(500EJ-AL**A)

CHASSIS NO. : CA-133

( ) **

Same model for Service

*Same looking with new chassis.

Issue Date; 2003. 5.

F ACTORY MODEL: 500EJ

1. PICTURE TUBE

Size : 15 inch (Flat Square Tube)
DefIection Angle : 90°
Neck Diameter : 29.1 mm
Dot Pitch : 0.28 mm
Face Treatment : AR-ASC (Anti-Reflection and

Anti-Static Coating)
AG(Anti-Glare)

Low Radiation : MPR-II, NON MPR II

2. SIGNAL

2-1. Horizontal & Vertical Sync

1) Input Voltage Level: Low= 0~1.2V, High= 2.5~5.5V

2) Sync Polarity : Positive or Negative

2-2. Video Input Signal

1) Voltage Level : 0 ~ 0.7 Vp-p
a) Color 0, 0 : 0 Vp-p
b) Color 7, 0 : 0.467 Vp-p
c) Color 15, 0 : 0.7 Vp-p

2) Input Impedance : 75 Ω

3) Video Color : R, G, B Analog

4) Signal Format : Refer to the Timing Chart

2-3. Signal Connector

15-pin D-Sub Connector (Attached Type)

2-4. Scanning Frequency

Horizontal : 30 ~ 54 kHz
Vertical : 50 ~ 120 Hz

3. POWER SUPPLY

3-1. Power Range

AC 100~240V (Free Voltage), 50/60Hz, 1.0A Max.

3-2. Power Consumption

4. DISPLAY AREA

4-1. Active Video Area :

• 285 x 215 mm (11.22" x8.46") - Max Image Size

• 270 x 200 mm (10.63"x 7.87") - Preset Image Size
4-2. Display Color : Full Colors
4-3. Display Resolution : 1024 x 768 / 60Hz

(Non-Interlace)

4-4. Video Bandwidth : 65 MHz

5. ENVIRONMENT

5-1. Operating Temperature: 10°C ~ 40°C

(Ambient)

5-2. Relative Humidity : 10%~ 90%

(Non-condensing)

5-3. Altitude : 3,000 m

6. DIMENSIONS (with TILT/SWIVEL)

Width : 356.0 mm (14.01")
Depth : 395.0 mm (14.37")
Height : 371.0 mm (14.61")

7. WEIGHT (with TILT/SWIVEL)

Net Weight : 11.5 kg (25.36 lbs)
Gross Weight : 13.7 kg (30.21 lbs)

CONTENTS

- 2 -

SPECIFICATIONS ................................................... 2

SAFETY PRECAUTIONS ........................................ 3

TIMING CHART ....................................................... 4

OPERATING INSTRUCTIONS ................................ 5

WIRING DIAGRAM ................................................. 6

BLOCK DIAGRAM ................................................... 7

DESCRIPTION OF BLOCK DIAGRAM.....................8

ADJUSTMENT ........................................................ 9

TROUBLESHOOTING GUIDE .............................. 11

EXPLODED VIEW...................................................21

REPLACEMENT PARTS LIST ............................... 23

PIN CONFIGURATION........................................... 28

SCHEMATIC DIAGRAM......................................... 30

PRINTED CIRCUIT BOARD................................... 32

SPECIFICATIONS

MODE

MAX

NORMAL (ON)

STAND-BY

SUSPEND

OFF

POWER CONSUMPTION

75 W

63 W
less than 15 W
less than 15 W
less than 5 W

LED COLOR

GREEN
GREEN

AMBER

AMBER

SAFETY-RELATED COMPONENT WARNING!

There are special components used in this color monitor
which 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 X-radiation, shock, fire, or other hazards. Do not
modify the original design without obtaining written
permission from manufacturer or you will void the original
parts and labor guarantee.

CAUTION:

No modification of any circuit should be
attempted.
Service work should be performed only after
you are thoroughly familiar with all of the
following safety checks and servicing
guidelines.

SAFETY CHECK

Care should be taken while servicing this color monitor
because of the high voltage used in the deflection circuits.
These voltages are exposed in such areas as the
associated flyback and yoke circuits.

FIRE & SHOCK HAZARD

An isolation transformer must be inserted between the

color monitor and AC power line before servicing the
chassis.

• In servicing, attention must be paid to the original lead
dress specially in the high voltage circuit. If a short
circuit is found, replace all parts which have been
overheated as a result of the short circuit.

• All the protective devices must be reinstalled per the
original design.

• Soldering must be inspected for the cold solder joints,
frayed leads, damaged insulation, solder splashes, or
the sharp points. Be sure to remove all foreign
materials.

IMPLOSION PROTECTION

All used display tubes are equipped with an integral
implosion protection system, but care should be taken to
avoid damage and scratching during installation. Use only
same type display tubes.

X-RADIATION

The only potential source of X-radiation is the picture tube.
However, when the high voltage circuitry is operating
properly there is no possibility of an X-radiation problem.
The basic precaution which must be exercised is keep the
high voltage at the factory recommended level; the normal
high voltage is about 24.5kV. The following steps describe
how to measure the high voltage and how to prevent X­radiation.

Note : It is important to use an accurate high voltage

meter calibrated periodically.

• To measure the high voltage, use a high impedance
high voltage meter, connect (–) to chassis and (+) to
the CDT anode cap.

• Set the brightness control to maximum point at full
white pattern.

• Measure the high voltage. The high voltage meter
should be indicated at the factory recommended level.

• If the meter indication exceeds the maximum level,
immediate service is required to prevent the possibility
of premature component failure.

• To prevent X-radiation possibility, it is essential to use
the specified picture tube.

CAUTION:

Please use only a plastic screwdriver to protect yourself
from shock hazard during service operation.

SAFETY PRECAUTIONS

- 3 -

TIMING CHART

- 4 -

VIDEO

SYNC

C

E

D

F

A

B

H – 31.47 31.78 25.42 6.36 3.81 1.91 0.64
V – 59.94 16.684 15.254 1.430 0.063 1.049 0.318
H + 37.50 26.67 20.32 6.35 2.03 3.81 0.51
V + 74.99 13.335 12.802 0.533 0.080 0.427 0.026
H + 48.363 20.667 15.574 4.923 2.092 2.462 0.369
V + 60.004 16.666 15.880 0.786 0.124 0.600 0.062
H + 53.68 18.63 14.22 4.41 1.14 2.70 0.57
V + 85.07 11.755 11.178 0.577 0.056 0.503 0.018

Mode

H/V

Sort

1

2

3

4

640x480

60Hz

1024x768

60Hz

800x600

85Hz

640x480

75Hz

<< Dot Clock (MHz), Horizontal Frequency (kHz), Vertical Frequency (Hz), Horizontal etc... (µs), Vertical etc... (ms) >>

Sync

Polarity

Frequency

Total Period

(E)

Video Active

Time (A)

Sync Duration

(D)

Blanking Time

(B)

Back Porch

(C)

Front Porch

(F)

Resolution

- 5 -

OPERATING INSTRUCTIONS

MENU

SELECT

FRONT VIEW REAR VIEW

AC Power Socket

Signal Connector

ID Label

Power ON/OFF Button

See Front Control Panel

Front Control Panel

1. Power ON/OFF Button

Use this button to turn the monitor on or off.

2. Power Indicator

This indicator lights up green when the monitor operates
normally; in DPMS (Energy Saving) mode, - stand-by,
suspend, or power off mode -its color changes to orange,
and if abnormal or damaging circuit turns out orange blink.

3. SELECT Button

Use this button to enter a selection in the on screen
display.

4. SET Button

Use these buttons to choose or adjust items in the on
screen display.

5. MENU Button

Use this button to enter or exit the on screen display.

1

3

4

5

2

MENU

SELECT

WIRING DIAGRAM

- 6 -

P501(option)

P301

P302

G2

P702

P701

T1

P402

P902

S

+

S

Signal
Cable

AC
Socket

FBT

BLOCK DIAGRAM

- 7 -

Input_power

100~240VAC

(50/60Hz)

Line

Filter

Degaussing

Circuit

[ OSD Control ]

Power

Control

(IC901)

TILT

Control

Circuit

6.3V

15V

E

2

PROM

(IC402)

5V

H-sync Signal

V-sync Signal

I

2

C DATA(SDA)

I

2

C CLOCK(SCL)

VIDEO

OSD+pre_Amp

(IC302)

Signal

cable

RGB

VIDEO

Main_Amp

(IC303)

H/V Sync Processor

( IC701 )

TDA4841

V-out

( IC601)

TDA4867J

H-out

(Q706)

H-Linearity

Correction

Circuit

X-RAY

Protection

Circuit

Vertical Blanking,

- 160V

15V

D/D

Feed Back

30V

12V

MICOM

(IC401)

SCL / SDA

H/V sync

PWM control signal

15V

15V

50V

DY CDT

Heater ( 6.3V )

I

2

C

I

2

C

I

2

C

H/V

Sync

Screen

H.V

R/G/B

Bias

R/G/B

Contrast

H-Drive

B-Drive

B+

15V

BRIGHTNESS/CONTRAST

COLOR CURVE

H / V POSITION

H / V SIZE

SPCC

TRAPIZODE

PIN BALANCE

PARALLELOGRAM

ROTATION

TOP CORNER

BOTTOM CORNER

RECALL

DEGAUSSING

MOIRE

LANGUAGE

RESET

OSD TIME

DPM Control

Circuit

6.3V

15V 80V

Voltage

feedback

Voltage

feedback

Degaussing

Coil

Dynamic Focus
Static Focus

TILT

Coil

50V

80V

15V

G2

G1

DC/DC Converter

FBT

( T701 )

Regulation

Circuit

SMPS

(T901)

5V 15V

CUT-OFF IC

(IC304)

5V

Auto

Beam

Limit

(Option)

DESCRIPTION OF BLOCK DIAGRAM

1. Line Filter & Associated Circuit

This is used for suppressing noise of power input line
flowing into the monitor and/or some noise generated in
the monitor flowing out through the power input line.
That is to say,this circuit prevents interference between
the monitor and other electric appliance.

2. Degaussing Circuit Coil.

The degaussing circuit consists of the degaussing coil,
the PTC(Positive Temperature Coefficient) thermistr
(TH901), and the relay(RL901). This circuit eliminate
abnormal color of the screen automatically by
degaussing the shadow mask in the CRT during turning
on the power switch.When you need to degaussing in
using the monitor,select DEGAUSS on the OSD menu.

3. SMPS(Switching Mode Power Supply).

This circuit is working of 90~264V AC(50/60Hz).
The operation procecedure is as below:

1)AC input voltage is rectified and smoothed by the
bridge diodes(D900) and the capacitor.

2)The rectified voltage(DC) is applied to the primary
coil of the transform(T901).

3)The control IC(IC901) generates switching pulse to
turn on and off the primary coil of the transformer
(T901) repeatedly.

4)Depending on turn ration of the transformer,the
secondary voltage appear at the secondary coils of
the transformer(T901).

5)These secondary voltage are rectified by each diode
(D941,D951,D961,D971,D942) and operate other
circuit.(horizontal and vertical deflection,video
amplifer,...etc.)

4. X-ray Protection Circuit

When the high voltage reaches to 29kV in an abnormal
state), voltage of IC401(MICOM) pin 35 come to about

2.5V.

Then MICOM control IC701 (Deflection controller)to
stophorizontal drive pulse and stop horizontal deflection.

5. Microprocessor Control Circuit

The operating procedure of MICOM(Microprocessor)
and its associating circuit is as fallow:

1) Horizontal and Vertical sync signals are supplied
from the signabl cable.

2) Microprocessor(IC401) discriminates the operating
mode from the sync polarity and resolution.

3) The Micom sets operating mode and offers the
controlled data.(H-Size,H-Position,V-Size,...)

4) The controlled data of each mode is stored in itself.

5) User can adjust screen condition by each OSD
function.the data of the adjusted condition is stored in
EEPROM(IC402).

6. Horizontal and Vertical Oscillation

This circuit generates the horizontal pulse and the
vertical pulse by taking the H and V sync signal.
This circuit consists of the H/V processor(IC701) and
the associate circuit.

7. D/D(DC to DC) Converter

This circuit supplies DC voltage to the horizontal
deflection output circuit by increasing DC 50V which is
the secdonary voltage of the SMPS in accordance with
the input horizontal sync signal.

8. Side-Pincushion & Trapezoid Correction Circuit

This circuit improve the side-pincushion and the
trapezoid distortion of the screen by mixing parabola
and saw-tooth wave to output of the horizontal
deflection D/D converter which is used for the supply
voltage (B + ) of the deflection circuit.

9. Horizontal Deflection Output Circuit

This circuit makes the horizontal deflection by supplying
the saw-tooth current to the horizontal deflection yoke.

10.

High Voltage Output & FBT(Flyback Transformer)

The high voltage output circuit is used for generating
pulse to the primry coil of the FBT(Flyback
Transformer(T701)). A boosted voltage about 24.5kV)
appears at the secondary of the FBT and it is suppliesd
to the anode, focus, and screen voltage of the CRT.

11.

H-Linearity Correction Circuit

This circuit corrects the horizontal linearity for each
horizontal sync frequency.

12.

Vertical Output Circuit

This circuit takes the vertical ramp wave from the IC701
and performs the vertical deflection by supplying the
saw-tooth current to the vertical deflection yoke.

13.

H & V Blanking and Brightness Control

Blanking circuit eliminate retrace line by supplying
negatinve pulse to the G1 of the CRT. And Brightness
control uses the R/G/B cut-off DC Level by IIC line.

14.

Image Rotation(Tilt)Circuit-Option

This circuit corrects the tilts of the screen by supplying
the image rotation signal to the tilt which is attached
near the deflection yoke of the CRT.

15.

Video Pre-AMP Circuit

This circuit amplifies the analog video signal from 0-

0.7V to 0-4V. It is operated by taking the clamp,R,G,B
drive and contrast signal from the MICOM(IC401).

16.

Video Output AMP Circuit

This the circuit amplifies the video signal which comes
from the video pre-amp circuit and amplifies it to applied
the CRT cathode.

- 8 -

- 9 -

ADJUSTMENT

GENERAL INFORMATION

All adjustment are thoroughly checked and corrected
when the monitor leaves the factory, but sometimes
several adjustments may be required.
Adjustment should be following procedure and after
warming up for a minimum of 30 minutes.

• Alignment appliances and tools.

- IBM compatible PC.

- Programmable Signal Generator.
(eg. VG-819 made by Astrodesign Co.)

- EPROM or EEPROM with saved each mode data.

- Alignment Adaptor and Software.

- Digital Voltmeter.

- White Balance Meter.

- Luminance Meter.

- High-voltage Meter.

AUTOMATIC AND MANUAL DEGAUSSING

The degaussing coil is mounted around the CDT so that
automatic degaussing when turn on the monitor. But a
monitor is moved or faced in a different direction, become
poor color purity cause of CDT magnetized, then

press

DEGAUSS on the OSD menu.

ADJUSTMENT PROCEDURE & METHOD

-Install the cable for adjustment such as Figure 1and run

the alignment program on the DOS for IBM compatible PC.

-Set external Brightness and Contrast volume to max position.

1. Checked for B+ Voltage.

1) Display cross hatch pattern at Mode 4.

2) Check D961 voltage to 50V ± 1V with.

2. Adjustment for High-Voltage.

1) Display cross hatch pattern at Mode 4.

2) DIST.ADJ→CTRL PWM → High Voltage Command.

3) Adjust High Voltage to 24.5kV

±

0.1 kVdc.

4) Press Enter Key.

3. Adjustment for Factory Mode (Preset Mode).

1) Display cross hatch pattern at Mode 1.

2) Run alignment program for 500EJ on the IBM
compatible PC.

3) EEPROM → ALL CLEAR → Y(Yes) command.

<Caution> Do not run this procedure unless the
EEPROM is changed. All data in EEPROM (mode
data and color data) will be erased.

4) Power button of the monitor turn off → turn on.

5) COMMAND→PRESET START→Y(Yes) command.

6) DIST. ADJ→CTRLRWM→TILT Command.

7) DIST. ADJ. → BALANCE command.

8) Adjust parallelogram as arrow keys to be the best
condition.

9) Adjust balance of pin-balance as arrow keys to be

the best condition.

10)

DIST. ADJ. → FOS. ADJ command.

11)

Adjust V-SIZE as arrow keys to 200±2mm.

12)

Adjust V-POSITION as arrow keys to center of the
screen.

13)

Adjust H-SIZE as arrow keys to 270±2mm.

14)

Adjust H-POSITION as arrow keys to center of the
screen.

15)

Adjust S-PCC (Side-Pincushion) as arrow keys to be
the best condition.

16)

Adjust TRAPEZOID as arrow keys to be the best
condition.

17)

Save of the Mode 1.

18)

Display from Mode 2 to 4 and repeat above from
number 10) to 17)

19)

PRESET EXIT → Y (Yes) command.

4. Adjustment for White Balance and Luminance.

1) Set the White Balance Meter.

2) Press the DEGAUSS on the OSD menu for
demagnetization of the CDT.

3) COLOR ADJ. → LUMINANCE command of the
alignment program.

4) Set Brightness and Contrast to Max position.

5) Display color 0,0 pattern at Mode 4.

6) COLOR ADJ.→ BIAS ADJ.→ COLOR No. → 1
command of the alignment program.

7) Check whether green color or not at R-BIAS and G­BIAS to min position and G-BIAS to 127(7F)
position. Sub-Brightness to 205(CD) position. Adjust
G2 (screen) command to 0.4

±

0.05FL of the raster

luminance.

8) Adjust R-BIAS and G-BIAS command to x=0.283

±

0.005 and y=0.298±0.005 on the White Balance
Meter with PC arrow keys.

9)

Adjust SUB-Brightnesscommand to 0.4±0.1FL of the
raster luminance.

10)

Adjust repeat number 8).

11)

After push the “ENTER” key.

11-1)

COMMAND → PRESET START → Y(Yes) command.

12)

Display color 15,0 full white pattern at Mode 4.

13)

DRIVE ADJ.→ No 1. command.

14)

Set Brightness and Contrast to Max position.

15)

Set SUB-CONTRAST Max 127(7F) (decimal) position.

16)

Set B-DRIVE to 80(50) at DRIVE of the alignment
program.

- 10 -

17-1)

Adjust R-DRIVE and B-DRIVE command to white
balance x=0.283

±

0.003 and y=0.298±0.003 on the

White Balance Meter with PC arrow keys.

17-2)

Display color 15,0 window pattern (70x70mm) at mode 4.

18)

Adjust SUB-CONTRAST command to 50±2FL .

19)

Display color 15,0 full white patten at Mode 4.

20)

Set Brightness and Contrast to Max position.

21)

COLOR ADJ. → LUMINANCE → ABL command.

22)

Adjust ABL to 32±1FL of the luminance.

23)

After push the “ENTER” key, and “COMMAND →
PRESET EXIT → Y(Yes)” command.

24)

Exit from the program.

5. Input EDID Data.

1) Display color 15,0 cross hatch pattern at Mode 4.

2) EEPROM → Write EDID command and confirm
“EDID Write OK!!” message of monitor.

3) Exit from the alignment program.

4) Power switch OFF/ON for EDID data save.

6. Adjustment for Focus.

1) Set the Brightness and Contrast to max position.

2) Display H character in full screen at Mode 4.

3) Adjust two Focus control on the FBT that focus
should be the best condition.