CONFIDENTIAL
LED TV
SERVICE MANUAL
CHASSIS : LT9KB
MODEL : 43LT340C0DB
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL71468401 (1907-REV00)
Copyright © 2019 LG Electronics Inc. All rights reserved. Only training and service purposes.
CONTENTS
CONTENTS ............................................................................................... 2
SAFETY PRECAUTIONS ......................................................................... 3
SERVICING PRECAUTIONS .................................................................... 4
SPECIFICATION ........................................................................................ 6
SOFTWARE UPDATE ............................................................................... 9
BLOCK DIAGRAM .................................................................................. 11
EXPLODED VIEW ................................................................................... 12
DISASSEMBLY GUIDE .......................................................................... 14
TROUBLE SHOOTING GUIDE ................................................. APPENDIX
-2- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SAFETY PRECAUTIONS
IMPORTANT SAFETY NOTICE
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 Leakage Current Hot Check (See below Figure)
Plug the AC cord directly into the AC outlet.
An isolation Transformer should always be used during the
servicing of a receiver whose chassis is not isolated from the AC Do not use a line Isolation Transformer during this check.
power line. Use a transformer of adequate power rating as this Connect 1.5 K / 10 watt resistor in parallel with a 0.15 uF capacitor
protects the technician from accidents resulting in personal injury between a known good earth ground (Water Pipe, Conduit, etc.)
from electrical shocks. and the exposed metallic parts.
Measure the AC voltage across the resistor using AC voltmeter
It will also protect the receiver and it's components from being with 1000 ohms/volt or more sensitivity.
damaged by accidental shorts of the circuitry that may be Reverse plug the AC cord into the AC outlet and repeat AC voltage
inadvertently introduced during the service operation. measurements for each exposed metallic part. Any voltage
measured must not exceed 0.75 volt RMS which is corresponds to
If any fuse (or Fusible Resistor) in this TV receiver is blown, 0.5 mA.
replace it with the specified. In case any measurement is out of the limits specified, there is
possibility of shock hazard and the set must be checked and
When replacing a high wattage resistor (Oxide Metal Film Resistor, repaired before it is returned to the customer.
over 1 W), keep the resistor 10 mm away from PCB.
Leakage Current Hot Check circuit
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 1 MΩ and 5.2 MΩ.
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.
-3- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SERVICING PRECAUTIONS
CAUTION: Before servicing receivers covered by this service 2. After removing an electrical assembly equipped with ES
manual and its supplements and addenda, read and follow the devices, place the assembly on a conductive surface such as
SAFETY PRECAUTIONS on page 3 of this publication. aluminum foil, to prevent electrostatic charge buildup or expo-
NOTE: If unforeseen circumstances create conflict between the sure of the assembly.
following servicing precautions and any of the safety precautions 3. Use only a grounded-tip soldering iron to solder or unsolder ES
on page 3 of this publication, always follow the safety precautions. devices.
Remember: Safety First. 4. Use only an anti-static type solder removal device. Some solder
removal devices not classified as “anti-static” can generate
General Servicing Precautions electrical charges sufficient to damage ES devices.
1. Always unplug the receiver AC power cord from the AC power 5. Do not use freon-propelled chemicals. These can generate
source before; electrical charges sufficient to damage ES devices.
a. Removing or reinstalling any component, circuit board mod- 6. Do not remove a replacement ES device from its protective
ule or any other receiver assembly. package until immediately before you are ready to install it.
b. Disconnecting or reconnecting any receiver electrical plug or (Most replacement ES devices are packaged with leads electri-
other electrical connection. cally shorted together by conductive foam, aluminum foil or
c. Connecting a test substitute in parallel with an electrolytic comparable conductive material).
capacitor in the receiver. 7. Immediately before removing the protective material from the
CAUTION: A wrong part substitution or incorrect polarity leads of a replacement ES device, touch the protective material
installation of electrolytic capacitors may result in an explo- to the chassis or circuit assembly into which the device will be
sion hazard. installed.
2. Test high voltage only by measuring it with an appropriate CAUTION: Be sure no power is applied to the chassis or circuit,
high voltage meter or other voltage measuring device (DVM, and observe all other safety precautions.
FETVOM, etc) equipped with a suitable high voltage probe. 8. Minimize bodily motions when handling unpackaged replace-
Do not test high voltage by "drawing an arc". ment ES devices. (Otherwise harmless motion such as the
3. Do not spray chemicals on or near this receiver or any of its brushing together of your clothes fabric or the lifting of your
assemblies. foot from a carpeted floor can generate static electricity suf-
4. Unless specified otherwise in this service manual, clean ficient to damage an ES device.)
electrical contacts only by applying the following mixture to the
contacts with a pipe cleaner, cotton-tipped stick or comparable General Soldering Guidelines
non-abrasive applicator; 10 % (by volume) Acetone and 90 % 1. Use a grounded-tip, low-wattage soldering iron and appropriate
(by volume) isopropyl alcohol (90 % - 99 % strength) tip size and shape that will maintain tip temperature within the
CAUTION: This is a flammable mixture. range or 500 °F to 600 °F.
Unless specified otherwise in this service manual, lubrication of 2. Use an appropriate gauge of RMA resin-core solder composed
contacts in not required. of 60 parts tin/40 parts lead.
5. Do not defeat any plug/socket B+ voltage interlocks with which 3. Keep the soldering iron tip clean and well tinned.
receivers covered by this service manual might be equipped. 4. Thoroughly clean the surfaces to be soldered. Use a mall wire-
6. Do not apply AC power to this instrument and/or any of its bristle (0.5 inch, or 1.25 cm) brush with a metal handle.
electrical assemblies unless all solid-state device heat sinks are Do not use freon-propelled spray-on cleaners.
correctly installed. 5. Use the following unsoldering technique
7. Always connect the test receiver ground lead to the receiver a. Allow the soldering iron tip to reach normal temperature.
chassis ground before connecting the test receiver positive (500 °F to 600 °F)
lead. b. Heat the component lead until the solder melts.
Always remove the test receiver ground lead last. c. Quickly draw the melted solder with an anti-static, suction-
8. Use with this receiver only the test fixtures specified in this type solder removal device or with solder braid.
service manual. CAUTION: Work quickly to avoid overheating the circuit
CAUTION: Do not connect the test fixture ground strap to any board printed foil.
heat sink in this receiver. 6. Use the following soldering technique.
a. Allow the soldering iron tip to reach a normal temperature
Electrostatically Sensitive (ES) Devices (500 °F to 600 °F)
Some semiconductor (solid-state) devices can be damaged eas- b. First, hold the soldering iron tip and solder the strand against
ily by static electricity. Such components commonly are called the component lead until the solder melts.
Electrostatically Sensitive (ES) Devices. Examples of typical ES c. Quickly move the soldering iron tip to the junction of the
devices are integrated circuits and some field-effect transistors component lead and the printed circuit foil, and hold it there
and semiconductor “chip” components. The following techniques only until the solder flows onto and around both the compo-
should be used to help reduce the incidence of component dam- nent lead and the foil.
age caused by static by static electricity. CAUTION: Work quickly to avoid overheating the circuit
1. Immediately before handling any semiconductor component or board printed foil.
semiconductor-equipped assembly, drain off any electrostatic d. Closely inspect the solder area and remove any excess or
charge on your body by touching a known earth ground. Alter- splashed solder with a small wire-bristle brush.
natively, obtain and wear a commercially available discharging
wrist strap device, which should be removed to prevent poten-
tial shock reasons prior to applying power to the unit under test.
-4- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
IC Remove/Replacement 3. Solder the connections.
Some chassis circuit boards have slotted holes (oblong) through CAUTION: Maintain original spacing between the replaced
which the IC leads are inserted and then bent flat against the cir- component and adjacent components and the circuit board to
cuit foil. When holes are the slotted type, the following technique prevent excessive component temperatures.
should be used to remove and replace the IC. When working with
boards using the familiar round hole, use the standard technique Circuit Board Foil Repair
as outlined in paragraphs 5 and 6 above. Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
Removal board causing the foil to separate from or "lift-off" the board. The
1. Desolder and straighten each IC lead in one operation by following guidelines and procedures should be followed whenever
gently prying up on the lead with the soldering iron tip as the this condition is encountered.
solder melts.
2. Draw away the melted solder with an anti-static suction-type At IC Connections
solder removal device (or with solder braid) before removing To repair a defective copper pattern at IC connections use the
the IC. following procedure to install a jumper wire on the copper pattern
Replacement side of the circuit board. (Use this technique only on IC connec-
1. Carefully insert the replacement IC in the circuit board. tions).
2. Carefully bend each IC lead against the circuit foil pad and
solder it. 1. Carefully remove the damaged copper pattern with a sharp
3. Clean the soldered areas with a small wire-bristle brush. knife. (Remove only as much copper as absolutely necessary).
(It is not necessary to reapply acrylic coating to the areas). 2. carefully scratch away the solder resist and acrylic coating (if
used) from the end of the remaining copper pattern.
"Small-Signal" Discrete Transistor 3. Bend a small "U" in one end of a small gauge jumper wire and
Removal/Replacement carefully crimp it around the IC pin. Solder the IC connection.
1. Remove the defective transistor by clipping its leads as close 4. Route the jumper wire along the path of the out-away copper
as possible to the component body. pattern and let it overlap the previously scraped end of the
2. Bend into a "U" shape the end of each of three leads remaining good copper pattern. Solder the overlapped area and clip off
on the circuit board. any excess jumper wire.
3. Bend into a "U" shape the replacement transistor leads.
4. Connect the replacement transistor leads to the corresponding At Other Connections
leads extending from the circuit board and crimp the "U" with Use the following technique to repair the defective copper pattern
long nose pliers to insure metal to metal contact then solder at connections other than IC Pins. This technique involves the
each connection. installation of a jumper wire on the component side of the circuit
board.
Power Output, Transistor Device
Removal/Replacement 1. Remove the defective copper pattern with a sharp knife.
1. Heat and remove all solder from around the transistor leads. Remove at least 1/4 inch of copper, to ensure that a hazardous
2. Remove the heat sink mounting screw (if so equipped). condition will not exist if the jumper wire opens.
3. Carefully remove the transistor from the heat sink of the circuit 2. Trace along the copper pattern from both sides of the pattern
board. break and locate the nearest component that is directly con-
4. Insert new transistor in the circuit board. nected to the affected copper pattern.
5. Solder each transistor lead, and clip off excess lead. 3. Connect insulated 20-gauge jumper wire from the lead of the
6. Replace heat sink. nearest component on one side of the pattern break to the lead
of the nearest component on the other side.
Diode Removal/Replacement Carefully crimp and solder the connections.
1. Remove defective diode by clipping its leads as close as pos- CAUTION: Be sure the insulated jumper wire is dressed so the
sible to diode body. it does not touch components or sharp edges.
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.
-5- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SPECIFICATION
NOTE : Specifications and others are subject to change without notice for improvement.
1. Application range 3. Test method
This specification is applied to the LED TV used LT9KB (1) Performance: LGE TV test method followed
chassis. (2) Demanded other specification
- Safety : CE, IEC specification
- EMC : CE, IEC
2. Test condition
Each part is tested as below without special appointment.
(1) Temperature: 25 °C ± 5 °C, CST: 40 °C ± 2 °C
(2) Relative Humidity: 65 % ± 10 %
(3) Power Voltage
: Standard input voltage (AC 100-240 V~, 50/60 Hz)
* 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 BOM.
(5) The receiver must be operated for about 5 minutes prior to
the adjustment.
4. General Specification
No Item Specification Remark
1 Receiving System NTSC-M, DVB-T, DVB-T2 Colombia
NTSC-M, DVB-T, DVB-T2 Only Taiwan
2 Available Channel VHF/UHF : 02~13
UHF : 14~69
CATV : 01~135
DTV : 2~69
3 Input Voltage AC 110V @ 60Hz Taiwan
AC 100-240 V @ 50/60 Hz Colombia
4 Market Taiwan / Colombia
5 Aspect Ratio 16:9
6 Tuning System FS
7 Operating Environment Temp : 0 ~ 40 deg
Humidity : ~ 80 %
8 Storage Environment Temp : -20 ~ 60 deg
Humidity : ~ 85 %
-6- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
5. External Input Support Format
5.1. Component Input (Y, CB/PB, CR/PR)
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed
1 720*576 15.625 50.00 13.5 SDTV ,DVD 576I
2 720*480 15.73 60.00 13.5135 SDTV ,DVD 480I
3 720*480 15.73 59.94 13.50 SDTV ,DVD 480I
4 720*576 31.25 50.00 27.00 SDTV 576P
5 720*480 31.50 60.00 27.027 SDTV 480P
6 720*480 31.47 59.94 27.00 SDTV 480P
7 1280*720 37.50 50.00 74.25 HDTV 720P
8 1280*720 45.00 60.00 74.25 HDTV 720P
9 1280*720 44.96 59.94 74.176 HDTV 720P
10 1920*1080 28.125 50.00 74.25 HDTV 1080I
11 1920*1080 33.75 60.00 74.25 HDTV 1080I
12 1920*1080 33.72 59.94 74.176 HDTV 1080I
13 1920*1080 56.25 50.00 148.50 HDTV 1080P
14 1920*1080 67.50 60.00 148.50 HDTV 1080P
15 1920*1080 67.432 59.94 148.352 HDTV 1080P
16 1920*1080 27.00 24.00 74.25 HDTV 1080P
17 1920*1080 26.97 23.94 74.176 HDTV 1080P
18 1920*1080 33.75 30.00 74.25 HDTV 1080P
19 1920*1080 33.71 29.97 74.176 HDTV 1080P
5.2. RGB
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed
DDC
1 640*350 31.468 70.09 25.17 EGA X
2 720*400 31.469 70.08 28.32 DOS O
3 640*480 31.469 59.94 25.17 VESA(VGA) O
4 800*600 37.879 60.31 40.00 VESA(SVGA) O
5 1024*768 48.363 60.00 65.00 VESA(XGA) O
6 1152*864 54.348 60.053 80.00 VESA O
7 1360*768 47.712 60.015 85.50 VESA (WXGA) O
8 1280*1024 63.981 60.020 108.0 VESA (SXGA) O FHD
9 1920*1080 66.587 59.934 138.5 HDTV 1080P O FHD
10 1920*1080 67.50 60.00 138.5 HDTV 1080P O FHD
-7- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
5.3. HDMI Input (PC/DTV)
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed
HDMI-PC
DDC
1 640*350 31.468 70.09 25.17 EGA X
2 720*400 31.469 70.08 28.32 DOS O
3 640*480 31.469 59.94 25.17 VESA(VGA) O
4 800*600 37.879 60.31 40.00 VESA(SVGA) O
5 1024*768 48.363 60.00 65.00 VESA(XGA) O
6 1152*864 54.348 60.053 80.00 VESA O
7 1360*768 47.712 60.015 85.50 VESA (WXGA) O
8 1280*1024 63.981 60.020 108.0 VESA (SXGA) O FHD only
9 1920*1080 67.50 60.00 148.5 HDTV 1080P O FHD only
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
HDMI-DTV
1 640*480 31.46 59.94 25.125 SDTV 480P
2 640*480 31.50 60.00 25.125 SDTV 480P
3 720*480 15.73 59.94 13.500 SDTV 480I Don’t insert in
4 720*480 15.75 60.00 13.514 SDTV 480I manual spec. out
5 720*576 15.62 50.00 13.500 SDTV 576I(DVB)
6 720*480 31.469 59.94 27.00 SDTV 480P
7 720*480 31.50 60.00 27.027 SDTV 480P
8 720*576 31.250 50.00 27.00 SDTV 576P
9 1280*720 37.50 50.00 74.25 HDTV 720P
10 1280*720 45.00 60.00 74.25 HDTV 720P
11 1280*720 44.96 59.94 74.176 HDTV 720P
12 1920*1080 28.125 50.00 74.25 HDTV 1080I
13 1920*1080 33.75 60.00 74.25 HDTV 1080I
14 1920*1080 33.72 59.94 74.176 HDTV 1080I
15 1920*1080 56.250 50.00 148.50 HDTV 1080P
16 1920*1080 67.50 60.00 148.50 HDTV 1080P
17 1920*1080 67.432 59.94 148.35 HDTV 1080P
18 1920*1080 27.00 24.00 74.25 HDTV 1080P
19 1920*1080 26.973 23.976 74.175 HDTV 1080P
20 1920*1080 33.75 30.00 74.25 HDTV 1080P
21 1920*1080 33.716 29.976 74.175 HDTV 1080P
-8- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SOFTWARE UPDATE
1. User Mode 2. Expert Mode
(1) Insert the USB memory stick to the USB port. (1) Menu -> General : press ‘7’ consecutively by remote control
(2) Automatically TV manager application is launched and until TV Manager application is launched.
detect the SW version.
(3) Select ‘UPDATE’ button.
(4) TV is updating.
(2) Select the menu.
(5) After finished the update, below Pop-up appears then TV
will reboot automatically.
(6) Check the updated SW Version and Tool Option
(3) Select the file.
* If the software version on the USB device is equal to or lower
than the version currently installed on the TV, it cannot be
updated in User Mode
(4) TV is updating.
-9- Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(5) After finished the update, below Pop-up appears then TV
will reboot automatically.
(6) Check the updated SW Version and Tool Option
- Ez Download : T he Ez Download utility enables users to
download multiple items all at once, e.g., TV
(CPU), Micom, TLL, Image, Icon, Video,
Pro:Idiom M Key files.
- Data Coning : make and apply clone file.
- Image Download : I mage Download downloads “Boot Logo
Image,” “Apps Background Image(s),” and
“Hotel Directory Image(s)” at once.
- Icon Download : Icon Download downloads “Hotel Icon on
Portal,” “Website Shortcut,” and “Input
Shortcut” images at once.
- Video Download : V ideo Download downloads “Hotel Video”
and “Welcome Video” files at once.
- Software Update: d ownload software firmware, Micom or
CPU firmware file.
- The target files should be located in “LG_DTV” folder.
(* Clone files should be copied to the root folder of the USB )
- The downloadable items differ depending upon model.
- 10 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
X-tal
24MHz
Analog
Tuner
DVB-T2/C
Digital
LVDS
Module
74.25M
AV/COMP NAND
(RCA jack type) Flash 2Gb
HDMI2(SIDE)
USB(side) HDMI1(REAR)
- 11 -
Main IC
232C
SPIDIF
Copyright ©
BLOCK DIAGRAM
MAX3232
Headphone(side) TVLink
RGB
Speaker AMP
Only for training and service purposes.
EXT
Sub Amp
Speaker
LAN
LG Electronics Inc. All rights reserved.
EXPLODED VIEW
IMPORTANT SAFETY NOTICE
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.
900
400
800
120
521
HS1
540
121
HP1
HR1
530
LV1
500
820
200A
200P
200T
700
A10
ARC1
AR1
- 12 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
EXPLODED VIEW (MODULE)
IMPORTANT NOTICE
MRC use only
* MRC : Module Repair Center
Optical Sheet
200PPR
POL(Rear)
200SR1
Rear Side
200P
Ass’y
Panel
200SL1
200PC
200PPF
POL(Front)
- 13 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
DISASSEMBLY GUIDE
3
1 4
2 2
3 3 3 3
5
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Only for training and service purposes.
6
6
6
6
6
6
7 7
A 6
A
6
B B B B
8 8
8 8
8 8
8 8
8 8 8
8 8
8 8
9 9
8 8
8
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Only for training and service purposes.
10
11
14 14
15
12
13
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Only for training and service purposes.
19
20 20
- 17 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
DISASSEMBLY GUIDE (MODULE)
[Case Top]
(Step 1) Disassemble the Main, PSU, SPK and S-PCB cable.
(Step 2) Disassemble tCase Top Screw.
* Case top screw (U/L/R/D) : 3/3/3/3ea – Total 12ea
(Step 3) Disassemble the Case Top
(Step 4) Remove the EMI Tape on the S-PCB and Separate the S-PCB
*EMI Tape : 2ea
- 18 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(Step 5) Disassemble the Panel.
(Step 6) Disassemble the guide panel.
(Step 7) Disassemble the Optical Sheet 2ea /Diffuser Plate 1ea
(Step 8) Disassemble the DPS, and the Reflector
* Rotate the DPS to remove (2 EA) * Be careful not to tear the Reflector sheet.
- 19 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
[LED Array Disassemble]
(1) Disassemle the CNT form LED Array.
(2) Separate the LED Array from Cover Bottom.
(3) Remove the double tape form Cover Bottom.
[LED Array Assemble]
(Step 1) Attach the Double Tape
1) Attach the Double Tape in Guide Line of Cover Bottom (3ea)
2) Remove the protect film of Double Tape
* Finish the Attached Double Tape (3ea)
(Step 2) Attach the LED Array
1) Attach the LED Array to the round hole on Cover Bottom embo.
2) Press the LED Array on the surface of Cover Bottom.
3) Connect the CNT to the LED Array.
* LED Array Total 3ea
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Only for training and service purposes.
TROUBLE SHOOTING GUIDE
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Main PCB
Main processor
1 DDR Memory
NAND Memory
1
Power 2 Audio AMP
from PSU
PANEL
Local key
IR
2
Audio
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Interconnection
1 Main PCB
2 PSU
3 PANEL FFC Cable
4 Local Key+IR ASSY
2
1 5 SPEAKER
3
5
4
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Contents of Standard Repair Process
No. Error symptom (High category) Error symptom (Mid category) Page Remarks
1 No video/Normal audio 1
2 No video/No audio 2
3 A. Video error Picture broken/ Freezing 3
4 Color error 4
Vertical/Horizontal bar, residual image,
5 5
light spot, external device color error
6 No power 6
B. Power error Off when on, off while viewing, power
7 7
auto on/off
8 No audio/Normal video 8
C. Audio error
9 Wrecked audio/discontinuation/noise 9
10 Remote control & Local switch checking 10
D. Function error
11 External device recognition error 11
12 E. Noise Circuit noise, mechanical noise 12
13 F. Exterior error Exterior defect 13
14 G.Commercial Feature IR OUT 14
First of all, Check whether there is SVC Bulletin in GSCS System for these model.
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error A. Video error date
symptom
No video/ Normal audio Revised date 1/14
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, LVDS Cable, Speaker Cable, IR B/D Cable,,,)
☞A1 ☞A18
No video Normal Y Check Back Light Y Check Power Y Replace T-con/Main
On Normal
Normal audio audio On with naked eye Board Board or module
voltage
13V
N N N
Move to No Check Power Board 13V output Repair Power
☞A18
video/No audio Board or parts
Replace Inverter
Normal Y
or module
voltage
End
N
Repair Power
Board or parts
※Precaution ☞A4 & A2
Always check & record S/W Version and White
Replace Main Board Re-enter White Balance value
Balance value before replacing the Main Board
1
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error A. Video error date
symptom
No video/ No audio Revised date 2/14
☞A18
No Video/ Check voltage of Y Check and
Normal
No audio Power Board ( 13V…) replace
voltage?
MAIN B/D
N End
Replace Power
Board and repair
parts
2
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error A. Video error date
symptom
Picture broken/ Freezing Revised date 3/14
. By using Digital signal level meter
☞ A3
. By using Diagnostics menu on OSD
Check RF Signal level ( Menu/Setting→ Channels→ Channel Tuning→ Manual Tuning → Check the Signal )
- Signal strength (Normal : over 50%)
- Signal Quality (Normal: over 50%)
Y Check whether other equipments have problem or not.
Normal
(By connecting RF Cable at other equipment)
Signal?
→ DVD Player ,Set-Top-Box, Different maker TV etc`
N
☞ A4
Check RF Cable
Normal Y Check SVC N Check Y
Connection Close
1. Reconnection Picture? S/W Version Bulletin? Tuner soldering
2. Install Booster N
Y
N
S/W Upgrade
N Contact with signal distributor
Normal
Picture? or broadcaster (Cable or Air)
Normal N
Y Picture? Replace
Main B/D
Y
Close
Close
3
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error A. Video error date
symptom
Color error Revised date 4/14
☞A6 ☞ A7
※ Check
Check color by input
and replace
-External Input Y Y Y
Color Link Cable Color Color
-COMPONENT / AV Replace Main B/D Replace module
error? and contact error? error?
-RGB
condition
-HDMI N N N
Check error End
color input
mode
☞A8 Check
External device Y
External Input/ external
Check Test pattern /Cable Replace Main/T-con B/D
Comp/AV/RGB device and
error normal
cable
N
Request repair
for external
device/cable
N
Check external External device Y
HDMI device and /Cable Replace Main/T-con B/D
error cable normal
4
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
A. Video error Established
Error date
symptom Vertical / Horizontal bar, residual image,
light spot, external device color error Revised date 5/14
Vertical/Horizontal bar, residual image, light spot Replace
Module
☞A6
☞ A7 N
Check color condition by input Check external
Check and
-External Input Screen Y device Y Screen N Screen
-Component / AV Normal? replace Link Replace Main/T-con B/D
normal? connection normal? normal?
-RGB Cable
condition
-HDMI
N N For LGD panel Y
Y
Request repair Replace Main B/D
Replace End End
module for external
☞A8 device
Check Test pattern
For other panel
External device screen error-Color error
Check screen
condition by input
-External Input External
Check S/W Version Check N
-Component/AV Input Connect other external N
version
-RGB error device and cable Screen Replace
-HDMI/DVI (Check normal operation of normal? Main/T-con
Y External Input, Comp/AV, B/D
Comp/AV/RGB RGB and HDMI/DVI by
Y
S/W Upgrade
error connecting Jig, pattern
Generator ,Set-top Box etc.
Request repair for
external device
Y
Connect other external
Normal N HDMI/
device and cable N
screen? DVI
(Check normal operation of Screen Replace
External Input, Comp/AV, normal? Main /T-con
Y RGB and HDMI/DVI by B/D
connecting Jig, pattern
Generator ,Set-top Box etc.
End
5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error B. Power error date
symptom
No power Revised date 6/14
☞A17 ☞A18
DC Power on Replace
Check Power LED Y Normal N Check Power Y
by pressing Power Key OK? Power
Logo LED On? operation? On ‘”High”
On Remote control B/D
. Stand-By: Red or Turn On
N Y
. Operating: Turn Off
Check Power cord Replace Main B/D
was inserted properly
☞A18
N Measure voltage of each output of Power B/D
Normal?
Y Y Y
※ Normal
voltage?
Replace Main B/D
Close Normal
Check ST-BY 3.5V
Y
voltage? N
☞A18 Replace Power B/D
N
Replace Power
B/D
6
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error B. Power error date
symptom
Off when on, off while viewing, power auto on/off Revised date 7/14
Check outlet
☞A19
N Y
Check A/C cord Error? Check Power Off CPU
Replace Main B/D Normal? End
Mode Abnormal
N
Check for all 3- phase
power out Y Abnormal Replace Power B/D
1
Fix A/C cord & Outlet ☞A18
and check each 3
(If Power Off mode
phase out
is not displayed) Normal Y
Replace Main B/D
Check Power B/D voltage?
voltage
N
※ Caution
Check and fix exterior Replace Power B/D
of Power B/D Part
* Please refer to the all cases which Status Power off List Explanation
"POWEROFF_REMOTEKEY" Power off by REMOTE CONTROL
can be displayed on power off mode.
"POWEROFF_OFFTIMER" Power off by OFF TIMER
"POWEROFF_SLEEPTIMER" Power off by SLEEP TIMER
"POWEROFF_INSTOP" Power off by INSTOP KEY
"POWEROFF_AUTOOFF" Power off by AUTO OFF
Normal "POWEROFF_ONTIMER" Power off by ON TIMER
"POWEROFF_RS232C" Power off by RS232C
"POWEROFF_RESREC" Power off by Reservated Record
"POWEROFF_RECEND" Power off by End of Recording
"POWEROFF_SWDOWN" Power off by S/W Download
"POWEROFF_UNKNOWN" Power off by unknown status except listed case
"POWEROFF_ABNORMAL1" Power off by abnormal status except CPU trouble
Abnormal
"POWEROFF_CPUABNORMAL" Power off by CPU Abnormal
7
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error C. Audio error date
symptom
No audio/ Normal video Revised date 8/14
☞A20 ☞A21+A18
No audio
Check user N Check audio B+
Normal Y
menu > Off 13V of Power
Screen normal voltage
Speaker off Board
Y N
Cancel OFF Replace Power Board and repair parts
Check N
Disconnection Replace MAIN Board End
Speaker
disconnection
Y
Replace Speaker
8
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error C. Audio error date
symptom
Wrecked audio/ discontinuation/noise Revised date 9/14
→ abnormal audio/discontinuation/noise is same after “Check input signal” compared to No audio
Wrecked audio/
☞A21+A18
Check and replace
Discontinuation/ Check audio
speaker and
Noise for B+ Voltage (13V)
connector
Check input all audio
signal Y Y
Signal
-RF
normal? Wrecked audio/
-External Input Normal
signal Discontinuation/
N Replace Main B/D voltage?
Noise only
for D-TV
N
Wrecked audio/
Discontinuation/
Replace Power B/D
Noise only
for Analog
(When RF signal is not
received)
Request repair to external Wrecked audio/ Replace Main B/D End
cable/ANT provider Discontinuation/
Noise only
for External Input
(In case of N
External Input Connect and check Normal
signal error) other external audio?
Check and fix device
external device Y
Check and fix external device
9
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
D. Function error Established
Error date
symptom
Remote control & Local switch checking Revised date 10/14
1. Remote control(R/C) operating error Replace
Main B/D
☞A22 ☞A22 ☞A22
Check & Repair N Check B+ Y Y
Check R/C itself Normal Y Normal Normal Check IR Normal
operating? Cable connection operating? 3.5V Voltage? Signal?
Operation Output signal
Connector solder On Main B/D
N
Y N N
☞A18
Check R/C Operating Check & Replace Close Check 3.5v on Power B/D Repair/Replace
When turn off light Baterry of R/C Replace Power B/D or IR B/D
in room Replace Main B/D
(Power B/D don’t have problem)
If R/C operate, Normal Y
operating? Close
Explain the customer
cause is interference
from light in room. N
Replace R/C
10
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error D. Function error date
symptom
External device recognition error Revised date 11/14
Y Check technical
Check External Input and
Signal information Technical N
input Component Replace Main B/D
input? - Fix information information?
Recognition error
signal
- S/W Version
N Y
HDMI/
Check and fix DVI
Fix in Replace Main B/D
external device/cable Recognition error
accordance
with technical
information
11
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error E. Noise date
symptom
Circuit noise, mechanical noise Revised date 12/14
Identify Check
Circuit
nose location of Replace PSU
noise
type noise
Mechanical Check location of
noise noise
※ When the nose is severe, replace the module
※ Mechanical noise is a natural (For models with fix information, upgrade the
phenomenon, and apply the 1st level S/W or provide the description)
description. When the customer does not OR
agree, apply the process by stage. ※ If there is a “Tak Tak” noise from the
※ Describe the basis of the description cabinet, refer to the KMS fix information and
in “Part related to nose” in the Owner’s then proceed as shown in the solution manual
Manual. (For models without any fix information,
provide the description)
12
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error F. Exterior defect date
symptom
Exterior defect Revised date 13/14
Zoom part with Module
Replace module
exterior damage damage
Cabinet
Replace cabinet
damage
Remote
control Replace remote control
damage
Stand
Replace stand
dent
13
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error G. Commercial Feature date
symptom
IR OUT error Revised date 14/14
☞A24 ☞A24
IR OUT Y
Check Y Check Suitable
Not working Same Replace MAIN Board End
RS-232 Connection Remote Controller Data Format
as Guide
data Format
N
N
Change cable Change Remote
14
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Contents of Standard Repair Process Detail Technical Manual
No. Error symptom Content Page Remarks
1 Check LCD back light with naked eye A1
A. Video error_ No video/Normal audio
2 Check White Balance value A2
TUNER input signal strength checking
3 A3
method
A. Video error_ video error /Video
4 lag/stop Version checking method A4
5 Tuner Checking Part A5
A. Video error _Vertical/Horizontal bar,
6 Connection diagram A6
residual image, light spot
Check Link Cable (EPI) reconnection
7 A7
A. Video error_ Color error condition
8 Adjustment Test pattern - ADJ Key A8
9 Exchange Main Board (1) A-1/5
10 Exchange Main Board (2) A-2/5
11 Defected Type caused by T-Con/ Exchange Power Board (PSU) A-3/5
Inverter/ Module
12 Exchange Module (1) A-4/5
13 Exchange Module (2) A-5/5
Continue to the next page
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Contents of Standard Repair Process Detail Technical Manual
Continued from previous page
No. Error symptom Content Page Remarks
14 Check front display LED A17
B. Power error_ No power
15 Check power input Voltage & ST-BY 3.5V A18
B. Power error_Off when on, off while
16 POWER OFF MODE checking method A19
viewing
Checking method in menu when there is no
17 A20
audio
C. Audio error_ No audio/Normal video
Voltage and speaker checking method when
18 A21
there is no audio
19 D. Function error Remote control operation checking method A22
IR OUT
20 G. Commercial - Cable connection A23
- Recommended data format
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom A. Video error_No video/Normal audio date
Revised
Content Check LCD back light with naked eye A1
date
After turning on the power and disassembling the case, check with the naked eye,
whether you can see light from locations.
A1
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom A. Video error_No video/Normal audio date
Revised
Content Check White Balance value A2
date
Entry
Entrymethod
method
1.1.Press
Pressthe
theADJ
ADJbutton
buttonononthe
theremote
remotecontroller
controllerforforadjustment.
adjustment.
2.2.Enter
Enterinto
intoWhite
WhiteBalance
Balanceofofitem
item6.13.
3.3.After
Afterrecording
recordingthe
theR,R,G,G,B B(GAIN,
(GAIN,Cut)
Cut)value
valueofofColor
ColorTemp
Temp
(Cool/Medium/Warm),
(Cool/Medium/Warm),re-enterre-enterthe
thevalue
valueafter
afterreplacing
replacingthe
theMAIN
MAINBOARD.
BOARD.
A2
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom A. Video error_Video error, video lag/stop date
TUNER input signal strength checking method Revised
Content date A3
Menu/Setting Channel Manual Tuning
When the signal is strong,
use the attenuator (-10dB, -
15dB, -20dB etc.)
A3
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom A. Video error_Video error, video lag/stop date
Version checking method Revised
Content date A4
1. Checking method for remote control for adjustment
Version
Press the IN-START with the remote
control for adjustment
A4
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom
A. Video error_Video error, video lag/stop
date
Revised
Content TUNER checking part A5
date
* Interface Jack depends on model
Checking method:
1. Check the signal strength or check whether the screen is normal when the external device is connected.
2. After measuring each voltage from power supply, finally replace the MAIN BOARD.
A5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error A. Video error _Vertical/Horizontal bar, Established
symptom residual image, light spot date
Revised
Content Connection diagram (1) date A6
* Interface Jack depends on model
As the part connecting to the external input, check
the screen condition by signal
A6
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom A. Video error_Color error date
Revised
Content Check Link Cable(FFC) reconnection condition date A7
Check the contact condition of the Link Cable, especially dust or mis insertion.
A7
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom
A. Video error_Color error
date
Adjustment Test pattern - ADJ Key Revised
Content date A8
You can view 6 types of patterns using the ADJ Key
Checking item : 1. Defective pixel 2. Residual image 3. MODULE error (ADD-BAR,SCAN BAR..)
4.Video error (Classification of MODULE or Main-B/D!)
A8
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange Main Board (1)
Solder defect, CNT Broken Solder defect, CNT Broken Solder defect, CNT Broken
Solder defect, CNT Broken T-Con
T-Con Defect,
Defect,
Solder
T-Con CNT
CNT
defect,CNT
Defect, Broken
Broken
CNTBroken
Broken Abnormal Power Section
Solder defect, Short/Crack Abnormal Power Section Solder defect, Short/Crack
A - 1/5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange Main Board (2)
Abnormal Power Section Abnormal Power Section Solder defect, Short/Crack
Solder defect, Short/Crack Fuse Open, Abnormal power section Abnormal Display
GRADATION Noise GRADATION
A - 2/5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange Power Board (PSU)
No Light Dim Light
Dim Light Dim Light
No picture/Sound Ok
A - 3/5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange the Module (1)
Press damage Press damage Press damage
Un-repairable Cases
In this case please exchange the module.
Crosstalk Crosstalk
A - 4/5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange the Module (2)
Vertical Block Vertical Line Vertical Block
Source TAB IC Defect Source TAB IC Defect Source TAB IC Defect
Horizontal
TAB ICBlock
Horizontal Block Horizontal line
Gate Defect Gate TAB IC Defect
Gate TAB IC Defect Gate TAB IC Defect Gate TAB IC Defect
Un-repairable Cases
In this case please exchange the module.
Horizontal Block
Gate TAB IC Defect
Gate TAB IC Defect
A - 5/5
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom B. Power error _No power date
Revised
Content Check front Power Indicator date A17
A17
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom
B. Power error _No power
date
Revised
Content Check power input voltage and ST-BY 3.5V A18
date
Check the DC 13V
A18
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error
symptom B. Power error _Off when on, off whiling viewing Established
date
Revised
Content POWER OFF MODE checking method date A19
Entry method
1. Press the IN-START button of the remote control for adjustment
2. Check the entry into adjustment item 3
A19
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom C. Audio error_No audio/Normal video
date
Revised
Content Checking method in menu when there is no audio date A20
Checking method
1. Press the Setting/Menu button on the remote control
2. Select the Audio function of the Menu
3. Select the Sound Out
4. Select TV Speaker
A20
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom C. Audio error_No audio/Normal video date
Voltage and speaker checking method Revised
Content date A21
when there is no audio
①
③ 1 SPK_R-
2 SPK_R+
Checking order when there is no audio 3 SPK_L-
4 SPK_L+
1.Check the contact condition of or 13V connector of Main Board
2. Measure the 13V input voltage supplied from Power Board
(If there is no input voltage, remove and check the connector)
3.Connect the tester RX1 to the speaker terminal and if you hear the Chik Chik sound when you touch the
GND and output terminal, the speaker is normal.
A21
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom D. Function error date
Revised
Content Remote control operation checking method date A22
*IR assy depends on model
IR & LOGO light Front
IR & LOGO light Rear
Eye LED IR
Checking order to check remote control
Checking order
1.Check IR cable condition between IR & Main board
2.Check the standby 3.5V
3.AS checking the Pre-Amp(IR LED light) , the power is in ON condition, an Analog Tester
needle should move slowly, otherwise, it’s defective.
A22
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom G. Commercial Feature date
IR OUT Error Revised
Content date A23
1) Check the Cable Connection.
2) Check the “Suitable Data Format” of remote controller.
A23
Copyright © 2019 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
