LG 22LJ4540PU User manual

P/NO :
CHASSIS :
MODEL :
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
SERVICE MANUAL
Any reproduction, duplication, distribution (including by way of email, facsimile or other electronic means),
publication, modification, copying or transmission of this Service Manual is STRICTLY PROHIBITED unless you
have obtained the prior written consent of the LG Electronics entity from which you received this Service Manual.
The material covered by this prohibition includes, without limitation, any text, graphics or logos in this Service
Manual.
Copyright © 2017 LG Electronics Inc. All rights reserved.
Only training and service purposes.
CONFIDENTIAL
MFL69169574 (1701-REV01)
22LJ4540 22LJ4540-PU
LU72A
LED TV

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Copyright © LG Electronics. Inc. All right reserved.
Only for training and service purposes
CONTENTS
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS ......................................................................... 3
SERVICING PRECAUTIONS.................................................................... 4
SPECIFICATION ....................................................................................... 6
SOFTWARE UPDATE............................................................................... 9
TROUBLE SHOOTING GUIDE............................................................... 10
BLOCK DIAGRAM.................................................................................. 14
EXPLODED VIEW .................................................................................. 15

- 3 - LGE Internal Use Only
Copyright © LG Electronics. Inc. All right reserved.
Only for training and service purposes
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the
Exploded View.
It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent
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.
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 1MΩand 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
1.5 Kohm/10W
0.15µF
To Instrument's
exposed
METALLIC PARTS
Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
AC Volt-meter
When 25A is impressed between Earth and 2nd Ground
for 1 second, Resistance must be less than 0.1
*Base on Adjustment standard
IMPORTANT SAFETY NOTICE
SAFETY PRECAUTIONS

- 4 - LGE Internal Use Only
Copyright © LG Electronics. Inc. All right reserved.
Only for training and service purposes
CAUTION: Before servicing receivers covered by this service
manual and its supplements and addenda, read and follow the
SAFETY PRECAUTIONS on page 3 of this publication.
NOTE: If unforeseen circumstances create conflict between the
following servicing precautions and any of the safety precautions on
page 3 of this publication, always follow the safety precautions.
Remember: Safety First.
General Servicing Precautions
1. Always unplug the receiver AC power cord from the AC power
source before;
a. Removing or reinstalling any component, circuit board
module or any other receiver assembly.
b. Disconnecting or reconnecting any receiver electrical plug or
other electrical connection.
c. Connecting a test substitute in parallel with an electrolytic
capacitor in the receiver.
CAUTION: A wrong part substitution or incorrect polarity
installation of electrolytic capacitors may result in an
explosion hazard.
2. Test high voltage only by measuring it with an appropriate high
voltage meter or other voltage measuring device (DVM,
FETVOM, etc) equipped with a suitable high voltage probe.
Do not test high voltage by "drawing an arc".
3. Do not spray chemicals on or near this receiver or any of its
assemblies.
4. Unless specified otherwise in this service manual, clean
electrical contacts only by applying the following mixture to the
contacts with a pipe cleaner, cotton-tipped stick or comparable
non-abrasive applicator; 10% (by volume) Acetone and 90% (by
volume) isopropyl alcohol (90%-99% strength)
CAUTION: This is a flammable mixture.
Unless specified otherwise in this service manual, lubrication of
contacts in not required.
5. Do not defeat any plug/socket B+ voltage interlocks with which
receivers covered by this service manual might be equipped.
6. Do not apply AC power to this instrument and/or any of its
electrical assemblies unless all solid-state device heat sinks are
correctly installed.
7. Always connect the test receiver ground lead to the receiver
chassis ground before connecting the test receiver positive
lead.
Always remove the test receiver ground lead last.
8. Use with this receiver only the test fixtures specified in this
service manual.
CAUTION: Do not connect the test fixture ground strap to any
heat sink in this receiver.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid-state) devices can be damaged easily
by static electricity. Such components commonly are called
Electrostatically Sensitive (ES) Devices. Examples of typical ES
devices are integrated circuits and some field-effect transistors and
semiconductor "chip" components. The following techniques
should be used to help reduce the incidence of component
damage caused by static by static electricity.
1. Immediately before handling any semiconductor component or
semiconductor-equipped assembly, drain off any electrostatic
charge on your body by touching a known earth ground.
Alternatively, obtain and wear a commercially available
discharging wrist strap device, which should be removed to
prevent potential shock reasons prior to applying power to the
unit under test.
2. After removing an electrical assembly equipped with ES
devices, place the assembly on a conductive surface such as
aluminum foil, to prevent electrostatic charge buildup or
exposure of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES
devices.
4. Use only an anti-static type solder removal device. Some solder
removal devices not classified as "anti-static" can generate
electrical charges sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate
electrical charges sufficient to damage ES devices.
6. Do not remove a replacement ES device from its protective
package until immediately before you are ready to install it.
(Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum foil
or comparable conductive material).
7. Immediately before removing the protective material from the
leads of a replacement ES device, touch the protective material
to the chassis or circuit assembly into which the device will be
installed.
CAUTION: Be sure no power is applied to the chassis or circuit,
and observe all other safety precautions.
8. Minimize bodily motions when handling unpackaged
replacement ES devices. (Otherwise harmless motion such as
the brushing together of your clothes fabric or the lifting of your
foot from a carpeted floor can generate static electricity
sufficient to damage an ES device.)
General Soldering Guidelines
1. Use a grounded-tip, low-wattage soldering iron and appropriate
tip size and shape that will maintain tip temperature within the
range or 500 ˚F to 600 ˚F.
2. Use an appropriate gauge of RMA resin-core solder composed
of 60 parts tin/40 parts lead.
3. Keep the soldering iron tip clean and well tinned.
4. Thoroughly clean the surfaces to be soldered. Use a mall wire-
bristle (0.5 inch, or 1.25cm) brush with a metal handle.
Do not use freon-propelled spray-on cleaners.
5. Use the following unsoldering technique
a. Allow the soldering iron tip to reach normal temperature.
(500 ˚F to 600 ˚F)
b. Heat the component lead until the solder melts.
c. Quickly draw the melted solder with an anti-static, suction-
type solder removal device or with solder braid.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
6. Use the following soldering technique.
a. Allow the soldering iron tip to reach a normal temperature
(500 ˚F to 600 ˚F)
b. First, hold the soldering iron tip and solder the strand against
the component lead until the solder melts.
c. Quickly move the soldering iron tip to the junction of the
component lead and the printed circuit foil, and hold it there
only until the solder flows onto and around both the
component lead and the foil.
CAUTION: Work quickly to avoid overheating the circuit
board printed foil.
d. Closely inspect the solder area and remove any excess or
splashed solder with a small wire-bristle brush.
SERVICING PRECAUTIONS

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IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent flat against the
circuit foil. When holes are the slotted type, the following technique
should be used to remove and replace the IC. When working with
boards using the familiar round hole, use the standard technique
as outlined in paragraphs 5 and 6 above.
Removal
1. Desolder and straighten each IC lead in one operation by gently
prying up on the lead with the soldering iron tip as the solder
melts.
2. Draw away the melted solder with an anti-static suction-type
solder removal device (or with solder braid) before removing the
IC.
Replacement
1. Carefully insert the replacement IC in the circuit board.
2. Carefully bend each IC lead against the circuit foil pad and
solder it.
3. Clean the soldered areas with a small wire-bristle brush.
(It is not necessary to reapply acrylic coating to the areas).
"Small-Signal" Discrete Transistor
Removal/Replacement
1. Remove the defective transistor by clipping its leads as close as
possible to the component body.
2. Bend into a "U" shape the end of each of three leads remaining
on the circuit board.
3. Bend into a "U" shape the replacement transistor leads.
4. Connect the replacement transistor leads to the corresponding
leads extending from the circuit board and crimp the "U" with
long nose pliers to insure metal to metal contact then solder
each connection.
Power Output, Transistor Device
Removal/Replacement
1. Heat and remove all solder from around the transistor leads.
2. Remove the heat sink mounting screw (if so equipped).
3. Carefully remove the transistor from the heat sink of the circuit
board.
4. Insert new transistor in the circuit board.
5. Solder each transistor lead, and clip off excess lead.
6. Replace heat sink.
Diode Removal/Replacement
1. Remove defective diode by clipping its leads as close as
possible to diode body.
2. Bend the two remaining leads perpendicular y to the circuit
board.
3. Observing diode polarity, wrap each lead of the new diode
around the corresponding lead on the circuit board.
4. Securely crimp each connection and solder it.
5. Inspect (on the circuit board copper side) the solder joints of
the two "original" leads. If they are not shiny, reheat them and if
necessary, apply additional solder.
Fuse and Conventional Resistor
Removal/Replacement
1. Clip each fuse or resistor lead at top of the circuit board hollow
stake.
2. Securely crimp the leads of replacement component around
notch at stake top.
3. Solder the connections.
CAUTION: Maintain original spacing between the replaced
component and adjacent components and the circuit board to
prevent excessive component temperatures.
Circuit Board Foil Repair
Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
board causing the foil to separate from or "lift-off" the board. The
following guidelines and procedures should be followed whenever
this condition is encountered.
At IC Connections
To repair a defective copper pattern at IC connections use the
following procedure to install a jumper wire on the copper pattern
side of the circuit board. (Use this technique only on IC
connections).
1. Carefully remove the damaged copper pattern with a sharp
knife. (Remove only as much copper as absolutely necessary).
2. carefully scratch away the solder resist and acrylic coating (if
used) from the end of the remaining copper pattern.
3. Bend a small "U" in one end of a small gauge jumper wire and
carefully crimp it around the IC pin. Solder the IC connection.
4. Route the jumper wire along the path of the out-away copper
pattern and let it overlap the previously scraped end of the good
copper pattern. Solder the overlapped area and clip off any
excess jumper wire.
At Other Connections
Use the following technique to repair the defective copper pattern
at connections other than IC Pins. This technique involves the
installation of a jumper wire on the component side of the circuit
board.
1. Remove the defective copper pattern with a sharp knife.
Remove at least 1/4 inch of copper, to ensure that a hazardous
condition will not exist if the jumper wire opens.
2. Trace along the copper pattern from both sides of the pattern
break and locate the nearest component that is directly
connected to the affected copper pattern.
3. Connect insulated 20-gauge jumper wire from the lead of the
nearest component on one side of the pattern break to the lead
of the nearest component on the other side.
Carefully crimp and solder the connections.
CAUTION: Be sure the insulated jumper wire is dressed so the
it does not touch components or sharp edges.

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SPECIFICATION
NOTE : Specications and others are subject to change without notice for improvement.
1. Application Range
This spec sheet is applied to the LU72A chassis.
2. Specication
Each part is tested as below without special appointment
1) Temperature : 25 ˚C ± 5 ˚C (77 ˚F ± 9 ˚F),
CST : 40 ˚C ± 5 ˚C
2) Relative Humidity : 65 % ± 10 %
3) Power Voltage : Standard input voltage
(100 V - 240 V ~, 50 / 60 Hz)
· Standard Voltage of each products is marked by models
4) Specication and performance of each parts are followed
each drawing and specication by part number in accord-
ance with BOM.
5) The receiver must be operated for about 5 minutes prior to
the adjustment.
3.Test method
1) Performance : LGE TV test method followed
2) Demanded other specication
- Safety : UL
- EMC : FCC
4. Model general specication
No Item Specication Remarks
1 Market AMERICA, CANADA, MEXICO LJ4540 / LF454Bseries is US only
MT49x Series is Mexico only.
2 Receiving system ATSC / NTSC-M / 64 & 256 QAM
3 Available Channel VHF 2-13, UHF 14-69, CATV 1-135, DTV 2-69, CADTV 1-135
4 Interface RF / Composite(CVBS) / Component / HDMI / D-Sub / USB 22,24 LJ4540, 24LF454B serise :
RF/ HDMI/USB(SVC only)
28 LJ4540 : RF/ HDMI/USB
MT49x serise : RF, Component/
CVBS/ HDMI/ DSUB/ USB
No Item Specication Remarks
1 RF Input Analog NTSC
DTV ATSC
2 HDMI Input (Rear) HDMI version 1.4/ support PC
Support HDCP
Rear : 1EA
3 Component Input
(Rear, 1EA)
Y/Pb/Pr 2xLJ4540 not support
4 CVBS Input ATSC/NTSC-M 2xLJ4540 / LF454B not support
5 USB (Side, 1EA) For My Media(Photo/Music List) Picture + Music
(only 284LJ4540 support)
6 D-Sub RGB-PC 2xLJ4540/LF454B not support
2xMT49DF not support
5. Feature and Function

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Only for training and service purposes
6. External Input Support Format
- RGB/ HDMI (PC) LJ4540/ LF454B/ MT49DF doesn’t support RGB
- HDMI (DTV)
No. Resolution H-freq(kHz) V-freq(Hz) Pixel clock(MHz) Remark
1 720* 480 31.469 / 31.5 59.94 / 60 27.00/ 27.03 SDTV 480P
2 720*576 31.25 50.00 27.864 SDTV 576P
3 1280*720 37.50 50.00 74.250 HDTV 720P
4 1280* 720 44.96 / 45 59.94 / 60 74.17/ 74.25 HDTV 720P
5 1920* 1080 33.72 / 33.75 59.94 / 60 74.17/ 74.25 HDTV 1080I
6 1920* 1080 28.125 50.00 74.25 HDTV 1080I
7 1920* 1080 27.00 24 74.25 HDTV 1080P
8 1920* 1080 33.75 30.00 74.25 HDTV 1080P
9 1920* 1080 56.250 50 148.5 HDTV 1080P
10 1920* 1080 67.43 / 67.5 59.94 / 60 148.35/ 148.50 HDTV 1080P
No. Resolution H-freq(kHz) V-freq(Hz) Pixel clock(MHz) Remark
1 720*400 31.468 70.080 28.321
2 640*480 31.469 59.940 25.175
3 640*480 37.500 75.000 31.500
4 800*600 37.879 60.317 40.000
5 800*600 46.875 75.000 49.500
6 1024*768 48.363 60.004 65.000
7 1024*768 56.476 70.069 75.000 HDMI(PC)
8 1024*768 60.023 75.029 78.750
9 1152*864 67.500 75.000 108.000
10 1280*720 45.000 60.000 74.250
11 1280*800 49.702 59.810 83.500
12 1280*1024 63.981 60.020 108.000
13 1280*1024 79.976 75.025 135.000
14 1400*1050 65.317 59.978 121.750
15 1440*900 55.935 59.887 106.500
16 1600*900 60.000 60.000 108.000
17 1680*1050 64.674 59.883 119.000
18 1680*1050 65.290 59.954 146.250
19 1920*1080 67.500 60.000 148.500

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Only for training and service purposes
- Component (MT49DF only, LJ4540/ LF454B doesn’t support component.)
No Specication Remark
Resolution H-freq(kHz) V-freq(Hz)
1 720x480 15.730 59.940 720x480i
2 15.750 60.000
3 31.470 59.940 720x480p
4 31.500 60.000
5 720x576 15.625 50.000 720x576p
6 31.250 50.000
7 1280x720 44.960 59.940 1280x720p
45.000 60.000
8 37.500 50.000
9 1920x1080 33.720 59.940 1920x1080i
10 33.750 60.000
11 28.125 50.000 1920x1080p
12 56.250 50.000
13 67.432 59.940
14 67.500 60.000
- Video Color Format : YcbCr 444, 422 (xvYcc is not supported)

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Copyright © LG Electronics. Inc. All right reserved.
Only for training and service purposes
SOFTWARE UPDATE
1. USB Download
1) Make New folder named “LG_DTV” and put ISP le(*.bin)
in the folder.
2) Put the USB Stick to the USB socket.
3) 3 Automatically detecting update le in USB Stick
- If your downloaded program version in USB Stick is
Low, it didn’t work. But your downloaded version is
High, USB data is automatically detecting.
4) TV Software Upgrade feature will be displayed.
5) Updating is starting.
6) Updating Completed, The TV will restart automatically.
* After downloading, have to adjust TOOL OPTION again.

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TROUBLE SHOOTING
1. No Power
Replace X300
N
Check C500
Voltage Level (19V)
Check Power connector
OK ? Replace Adapter
Y
N Y
Check IC1001 Output
Voltage Level (3.3V)
Replace IC1001 &
Recheck
Y
N
Check X300 Clock
24MHz
Replace IC405 Flash
Memory
Y
Check IC503 Output
Voltage Level (5V)
Replace IC503 &
Recheck
Y
N
Check IC504 Output
Voltage Level (1.15V)
Replace IC504 &
Recheck
N
Y

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Only for training and service purposes
2. No Screen on
Replace Cable
N
Module Back Light On?
Check IC1001 & Q1002
Replace LED Driver IC or FET
Y
N
N
Check Panel Power 5V (P402 #1)
or Check IC503 Output 5V
Replace IC503 or IC500 &
Recheck
Y
N
Check Panel input Clock
P402 (#10, #11 )
Check IC300
Repair Main B/D
Y
N
Check FFC Cable for Damage or
Open Conductors
Check LED Driver Output
(C1024)
Replace T-Con Board or Module
Y
Check IC300
Replace Main SOC
N
Check WLED_ENABLE High?
Y

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3. No Video - Digital TV
Check RF Cable
Y
1. Check RF IC(L200) Power (3.3V)
2. Check IC1001 Output voltage(3.3V)
Replace IC1001 &
Recheck
Y
N
Check SCL/SDA Line(TU200 #1, #2) Replace TU200 or
IC300(=> Main Scaler)
N

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Only for training and service purposes
4. No Video - HDMI
Replace Main Scaler
(IC300)
Check input signal format
Is it supported?
Check JK100 for proper
connection or Damage Replace Connector
Y
N
Check I2C Signal
(JK100) Re Download EDID Data
Y
N
Y
Check HDMI Cable for Damage or
Open Connector
Y

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BLOCK DIAGRAM

- 15 - LGE Internal Use Only
Copyright © LG Electronics. Inc. All right reserved.
Only for training and service purposes
EXPLODED VIEW
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts
are identified by in the EXPLODED VIEW.
It is essential that these special safety parts should be replaced with the same components as recommended
in this manual to prevent Shock, Fire, or other Hazards.
Do not modify the original design without permission of manufacturer.
IMPORTANT SAFETY NOTICE
300 200
120
900
540
831 541
832
400
510
LV1
A2
730
910