lg 21FU3RL Service Manual

COLOR TV

SERVICE MANUAL

CAUTION

BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

CHASSIS : CW81A

MODEL : 21FU3RL

21FU3RL-T3

website:http://biz.LGservice.com

Internal Use Only

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Only for training and service purposes

CONTENTS

Contents ....................................................................................................2

Safety Precautions....................................................................................3

Specifications............................................................................................4

Adjustment Instructions...........................................................................5

Trouble Shooting ......................................................................................8

Block Diagram.........................................................................................13

Exploded View.........................................................................................14

Exploded View Parts List .......................................................................15

Replacement Parts List ..........................................................................16

SVC. Sheet...................................................................................................

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Only for training and service purposes

SAFETY PRECAUTIONS

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the Schematic Diagram and Replacement Parts List. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer.

General Guidance

An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks.

It will also protect the receiver and it's components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.

If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified.

When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the resistor 10mm away from PCB.

Keep wires away from high voltage or high temperature parts.

Due to high vacuum and large surface area of picture tube, extreme care should be used in handling the Picture Tube. Do not lift the Picture tube by it's Neck.

X-RAY Radiation

Warning:

To determine the presence of high voltage, use an accurate high impedance HV meter.

Adjust brightness, color, contrast controls to minimum. Measure the high voltage. The meter reading should indicate

23.5 ± 1.5KV: 14-19 inch, 26 ± 1.5KV: 19-21 inch,

29.0 ± 1.5KV: 25-29 inch, 30.0 ± 1.5KV: 32 inch If the meter indication is out of tolerance, immediate service and correction is required to prevent the possibility of premature component failure.

Before returning the receiver to the customer,

always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Leakage Current Cold Check(Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc. If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1MΩ and 5.2MΩ. When the exposed metal has no return path to the chassis the reading must be infinite. An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage Current Hot Check (See below Figure)

Plug the AC cord directly into the AC outlet.

Do not use a line Isolation Transformer during this check.

Connect 1.5K/10watt resistor in parallel with a 0.15uF capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts. Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity. Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each exposed metallic part. Any voltage measured must not exceed 0.75 volt RMS which is corresponds to

0.5mA. In case any measurement is out of the limits specified, there is possibility of shock hazard and the set must be checked and repaired before it is returned to the customer.

Leakage Current Hot Check circuit

The source of X-RAY RADIATION in this TV receiver is the High Voltage Section and the Picture Tube. For continued X-RAY RADIATION protection, the replacement tube must be the same type tube as specified in the Replacement Parts List.

IMPORTANT SAFETY NOTICE

0.15uF

To Instrument's exposed METALLIC PARTS

AC Volt-meter

Good Earth Ground such as WATER PIPE, CONDUIT etc.

1.5 Kohm/10W

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Only for training and service purposes

SPECIFICATIONS

Note : Specification and others are subject to change without notice for improvement.

1. Scope

This specification is applied to the CW81A Chassis.

2. Test and Inspection Method

1) performance : LGE TV test method followed.

2) Demanded other specification

- Safety: CB Spec.(EN60065)

- EMC: CE Spec.(EN55020,EN55013)

3. Test Condition

Each part is tested as below without special appiontment

1) Temperature : 20

± 5°C(77 ± 9°F), CST : 40 ± 5°C

2) Relative Humidity : 65

± 10%

3) Power Voltage : Standard input voltage 220V, 50/60Hz * Standard Voltage of each products is marked by models.

4) Specification and performance of each parts are followed each drawing and specification by part number in accordance with B.O.M.

5) The receiver must be operated for about 20 minutes prior to the adjustment.

Item Specification Remark

Receiving System PAL BG,DK,I / NTSC M(AV3.58/4.43) China/ Indonesia/ Thai/ Vietnam

PAL BG,DK,I / NTSC M(AV3.58/4.43) CIS SECAM DK PAL BG,DK,I / NTSC M(AV3.58/4.43) Asia/ Middle East/ Africa SECAM BG,DK,L

Available Channel VHF : E2 ~ E12

UHF : E21 ~ E69 CATV : S1 ~ S20 HYPER : S21 ~ S41

Input Voltage 220V~, 50/60Hz East Asia

100-240V~, 50/60Hz Others Market China, Indonesia, Thai, Vietnam, Asia/Africa Screen Size 14 ~ 21 inch (Flat / Conventional)

21” Super slim/ultra slim Aspect Ratio 4:3 Display Method CRT Tuning System FVS Operating Environment 1) Temp : 0 ~ 40 deg

2) Humidity : ~ 85 %

Storage Environment 3) Temp : -20 ~ 60 deg

4) Humidity : ~ 90 %

4. General Specification

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Only for training and service purposes

1. Application Object

These adjustment instructions are applicable to CW81A/B Chassis.

2. Notes

(1) Because this is a cold chassis, it is not necessary to use

an isolation transformer. However,operating it using a

transformer between the power supply line and chassis

input to prevent electric shock and to protect the test instrument.

(2)All adjustments must be done in correct sequence.

However, for better productivity, it can be changed in a prepermitted range.

(3) Environment conditions: If not specified, it must be done in

following conditions.

1) Temperature: 25±5°C

2) Humidity : 65±10% (4) AC Voltage : 100-240V ±10%, 50/60Hz (5) If not specified, the receiver must be operated for more

than 20 minutes prior to the adjustment.

(6) Signal: Received the standard color signal. (65dB±1dBuV)

PAL/SECAM : LG standard signal means the digital pattern PAL_EU 05CH

(7) If not specified, APC ON is APC CLEAR(DYNAMIC).

3. AGC Voltage Adjustment

3-1. Necessary Instrument

: Digital Multi meter : 1 set

- Max Input Current : Over 1A/ Max Input Voltage : 500Vdc

- Measurement Range : 10mV-100mVdc/ Accuracy : 0.03%

3-2. Adjustment Preparation

1) Input in the 75Ω cable 65dB(±1dB) LG standard signal.

2) Connect the multi-meter to J105(AGC Check Marking)

3-3. Adjustment

(1) Press the “INSTART” key of factory remote control and

select “VP0 (RF AGC)” adjustment mode.

(2) Press the VOL +/-(

F/G)Key until the multi-meter shows

reading as shown below.

(3) CAUTION : Since the signal strength can be easily

changed by the condition of signal cable , you need to check the signal strength frequently in order to prevent misadjustment.

4. Screen Voltage Adjustment

4-1. Adjustment (Use factory remote control)

(1) Input in the 75Ω cable LG standard signal (Digital

Pattern,480NC)

(2) Press the “ADJ” key of factory remote control once to make

the TV set display horizontal line.

(3) Turn the screen volume on the FBT clockwise until the

horizontal line is visible and turn it counterclockwise until horizontal line faintly visible.

(Exit screen voltage adjustment by press “Enter(

A)” key of

factory remote control.)

5. Purity and Convergence Adjustment

5-1. Purity Adjustment

(1) Adjustment Preparation

1) Receive Red Raster Pattern for purity adjustment.(51ch)

2) Demagnetize the CPT and Cabinet with a degaussing coil.

(2) Adjustment

1) Pre-adjust the static convergence (STC) with the 4 and 6pole magnet.

2) If the horizontal Line is inline with CPT Mark,2-Pole magnet should direct 3-9 o’clock direction

3) If not,direct 2-Pole magnet handle toward 6-12 o’clock direction and adjust the Horizontal Line to fall onto the mark opening the magnet at an angle.

4) Push the DY(deflection yoke) all the way to the CPT funnel.

5) Turn the purity magnet(2-pole magnet) so that the “green” color portion of left side and the “blue” color portion on the right side have equal amount of color.

6) Pull the DY slowly backward and fix it when the whole screen becomes red. (The specified torque for fixing DY screw should be 10Kg/cm.)

5-2. Convergency Adjustment

(1) Necessary Instrument

1) Degaussing Coil

2) Convergency fixing instrument (special tools)

(2) Adjustment Preparation

1) Operate the unit at the least 15 minutes before

adjustment.

2) Using degaussing coil,remove the stains on CPT &

Cabinet.

3) Received the Cross Hatch Pattern for Convergence

(09ch).

4) Let the Contrast in normal luminance level.

ADJUSTMENT INSTRUCTIONS

G R B

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