LG 21FU3RL User 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...................................................................................................

- 3 - LGE Internal Use OnlyCopyright © 2008 LG Electronics. Inc. All right reserved.
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.
1.5 Kohm/10W
To Instrument's
exposed
METALLIC PARTS
Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
AC Volt-meter
IMPORTANT SAFETY NOTICE
0.15uF

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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 pre-
permitted 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 G R B
R
G R B
<Fig. 1>
<Fig. 2>