LG 900B, CB997G-EL Full

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.

MODEL: StudioWorks 900B (CB997G-EL)

CHASSIS NO. : CA-123

F ACTORY MODEL: CB997G

*( ) ID LABEL Model No.

MENU SELECT

1. PICTURE TUBE

Size : 19 inch (Flat Slot Mask) DefIection Angle : 90° Neck Diameter : 29.1 mm Phosphor : P22 Slot Pitch : 0.26 mm Face Treatment : Anti-Glare

2. SIGNAL

2-1. Horizontal & Vertical Sync

1) Input Voltage Level: Low= ≤0.8V, High= ≥2.1V

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

2-4. Scanning Frequency

Horizontal : 30~98 kHz Vertical : 50~160 Hz

3. POWER SUPPLY

3-1. Power Range

AC 100~240V, 50/60HZ, 2.5A Max AC 200~240V, 50Hz, 1.5A Max.(PFC version)

3-2. Power Consumption

4. DISPLAY AREA

4-1. Active Video Area :

• Max Image Size - 365.8 x 274.3mm (12.91" x 9.61")

• Preset Image Size - 350 x 262 mm (12.20" x 9.06") 4-2. Display Color : Full Colors 4-3. Display Resolution : 1600 Dots x 1200Lines 4-4. Video Bandwidth : 203MHz

5. ENVIRONMENT

5-1. Operating Temperature: 0°C~40°C (32°F~103°F)

(Ambient)

5-2. Relative Humidity : 8%~80%

(Non-condensing)

5-3. Altitude : 10,000 ft

6. DIMENSIONS (with TILT/SWIVEL)

Width : 448 mm (17.64") Depth : 470 mm (18.50") Height : 454 mm (17.87")

7. WEIGHT (with TILT/SWIVEL)

Net Weight : 19.0 kg (41.89 lbs) Gross Weight : 22.5 kg (49.61 lbs)

CONTENTS

SPECIFICATIONS

- 2 -

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

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

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

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

CONTROL LOCATIONS ......................................... 6

WIRING DIAGRAM ................................................. 7

DISASSEMBLY ....................................................... 8

BLOCK DIAGRAM ................................................... 9

DESCRIPTION OF BLOCK DIAGRAM...................10

ADJUSTMENT ...................................................... 12

TROUBLESHOOTING GUIDE .............................. 14

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

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

PIN CONFIGURATION .......................................... 29

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

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

MODE

MAX

NORMAL (ON)

STAND-BY SUSPEND

OFF

H/V SYNC

ON/ON OFF/ON ON/OFF

OFF/OFF

POWER CONSUMPTION

less than 110W less than 83W less than 8W less than 8W less than 3W

LED COLOR

GREEN GREEN

AMBER

SAFETY PRECAUTIONS

- 3 -

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 26kV. 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.

TIMING CHART

- 4 -

VIDEO

SYNC

kHz

µs µs µs µs µs µs

Hz ms ms ms ms ms ms

MODE 1

–

43.269

23.112

17.778

5.334

1.556

2.222

–

85.008

11.763

11.093

0.670

0.023

0.069

0.578

640

480

85Hz

Yes

MODE 2

53.674

18.631

14.222

4.409

0.569

1.138

2.702 +

85.061

11.756

11.178

0.578

0.019

0.056

0.503

800

600

85Hz

Yes

MODE 3

68.677

14.561

10.836

3.725

0.508

1.016

2.201 +

84.997

11.765

11.183

0.582

0.015

0.044

0.523

1024

768

85Hz

Yes

MODE 4

91.146

10.971

8.127

2.844

0.406

1.016

1.422 +

85.024

11.762

11.235

0.527

0.011

0.033

0.483

1280

1024 85Hz

Yes

MODE 5

93.750

10.666

7.901

2.765

0.316

0.948

1.501 +

75.000

13.333

12.800

0.533

0.011

0.032

0.490

1600

1200 75Hz

MARK

A B C D E F

MODE

FACTORY PRESET MODE

Resolution

Recall

H O R

I Z O N T A L

V E R T

I C A L

Sync Polarity

Frequency

Total Period

Video Active Time

Blanking Time

Front Porch

Sync Duration

Back Porch

Sync Polarity

Frequency

Total Period

Video Active Time

Blanking Time

Front Porch

Sync Duration

Back Porch

VESA

* Mode 5 is not preset mode but TCO check resolution!

OPERATING INSTRUCTIONS

- 5 -

FRONT VIEW REAR VIEW

AC Power Socket

Signal Connector

ID Label

Front Control Panel

MENU SELECT

Power ON/OFF Button

See Front Control Panel

MENU SELECT

Buttons

MENU Button

Power Button

Power (DPMS) Indicator

SELECT Button

• Brightness and Contrast can be adjusted directly without entering the On Screen Display (OSD) system. Press the buttons to adjust the settings and then the MENU button to save all changes. The Brightness and Contrast functions are also available in the On Screen Display (OSD) menu.

100

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 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. 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.

CONTROL LOCATIONS

- 6 -

VR801 : High Voltage Adjustment (26kV)

VR901: B Adjustment

(190V Line)

WIRING DIAGRAM

- 7 -

DY-Pin

Degaussing Coil

P702

P402

P401

P901

DY Assembly Screw

P801

P201-

(Control PCB)

Anode Cap

P451

SELECT

DISASSEMBLY

- 8 -

Tip Spec.

A(Width) : 5.0~13.0mm B(Depth) : 0.6~0.9mm C(Height) : 12.0mm

1. TILT/SWIVEL & BACK COVER REMOVAL

1) Set the monitor face downward.

2) Pull the latch (a), carefully remove the Tilt/Swivel by pulling it upward.

3) Pressing the latch (b), Back cover by pushing it upward.

4) Release the latch (c).

5) Slide the Back Cover away from the Front Cabinet of the monitor.

Back Cover

(c)

Cabinet

(a)

Tip

(b)

BLOCK DIAGRAM

- 9 -

SIGNAL

INPUT

DESCRIPTION OF BLOCK DIAGRAM

- 10 -

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 this monitor flowing out through the power input line. That is to say, this circuit prevents interference between the monitor and other electric appliances.

2. Degauss Circuit & Coil.

The degauss circuit consists of the degaussing coil, the PTC (Positive Temperature Coefficient) thermistor (TH901), and the relay (RL901). This circuit eliminates abnormal color of the screen automatically by degaussing the slot mask in the CDT when turn on the power switch. When you need to degauss while using the monitor, select DEGAUSS on the OSD menu.

3. SMPS (Switching Mode Power Supply).

This circuit works with power of 100~240V or 200~240V (50/60Hz) specially for PFC version.

The operation procedure is as follows:

1) AC input voltage is rectified and smoothed by the bridge diode (D901) and the capacitor (C905).

2) The rectified voltage (DC voltage) is applied to the primary coil of the transformer (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 the turn ratio of the transformer, the secondary voltages appear at the secondary coil of the transformer (T901).

5) These secondary voltages are rectified by each diode (D924, D926, D923, D922, D921, D920) and operate the other circuits. (Deflection, Video Amplifier, etc.)

4. Display Power Management Circuit.

This circuit control power consumption of the monitor by detecting H and V sync signal. There are stand-by and suspend mode. When no horizontal or vertical sync signal input, the circuit consists of Q913 and Q915 becomes stand-by and suspend mode. It’s power consumption is below 8W. When no horizontal and vertical sync signal input, it’s power consumption is below 3W.

5. X-ray Protection.

This circuit detects the rectified DC voltage comes from the FBT pin 4. If the high voltage of the FBT reaches up to about 30kV (abnormal state), H.V control (IC802) detects. It stops B+voltage supplied to the FBT (T701), and high voltage is not be generated, (In the normal state, the high voltage is about 26kV.)

6. Micom(Microprocessor) Circuit.

The operating procedure of Micom (Microprocessor) and its associated circuit is as follows:

1) H and V sync signal is supplied from Signal Cable t o t h e Micom (IC401).

2) The Micom (IC401) distinguishes polarity and frequency of H and V sync.

3) The Micom controls each OSD function signals. (H-size, H-position, V-size, etc.)

4) The controlled data of each mode is stored in IC402. User can adjust screen condition by each OSD function. The data of the adjust screen condition is stored automatically.

7. Horizontal and Vertical Synchronous Processor.

This circuit generates the horizontal drive pulse and the vertical drive pulse by taking sync-signal from Signal Cable. This circuit consists of the TDA4841(IC801) and the associated circuit.

8. Oscillating Circuit for D/D Converter.

This circuit generates the pulse wave which has the horizontal period by taking the output of the TDA4841 (IC801).

9. D/D (DC to DC) Converter.

This circuit supplies DC voltage to the horizontal deflection output circuit by decreasing DC 190V which is the secondary voltage of the SMPS in accordance with the input horizontal sync signal.

10. Side-Pincushion Correcting Cirucit.

This circuit improves the Side-pincushion of the screen by mixing east-west wave to the output of the horizontal deflection D/D converter which is used for the supply voltage source (B+) of the deflection circuit.

+ 22 hidden pages