LG 55UN6950 User manual

P/NO : MFL71703814 (2104-REV02)
CHASSIS : UAX3E
MODEL : 55UN6950/6951ZUA
55UN6900/7000PUB/55UN7100PUA
55UN6955ZUF
LED TV
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS 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 © 2021 LG Electronics Inc. All rights reserved. Only training and service purposes.

- 2 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
CONTENTS
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS ........................................................................ 3
SERVICING PRECAUTIONS ................................................................... 4
SPECIFICATION .......................................................................................6
SOFTWARE UPDATE ............................................................................. 9
BLOCK DIAGRAM ................................................................................. 10
EXPLODED VIEW .................................................................................. 11
ASSEMBLY / DISASSEMBLY GUIDE ................................................... 13
TROUBLE SHOOTING GUIDE ................................................ APPENDIX

- 3 - Copyright © LG Electronics Inc. All rights 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 1 W), keep the resistor 10 mm 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 1 MΩand 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.
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 1.5 K / 10 watt resistor in parallel with a 0.15 uF 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
0.5 mA.
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
IMPORTANT SAFETY NOTICE
SAFETY PRECAUTIONS

- 4 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SERVICING PRECAUTIONS
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 conict 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 mod-
ule 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 explo-
sion 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 specied 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 ammable mixture.
Unless specied 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 xtures specied in this
service manual.
CAUTION: Do not connect the test xture ground strap to any
heat sink in this receiver.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid-state) devices can be damaged eas-
ily by static electricity. Such components commonly are called
Electrostatically Sensitive (ES) Devices. Examples of typical ES
devices are integrated circuits and some eld-e󰀨ect transistors
and semiconductor “chip” components. The following techniques
should be used to help reduce the incidence of component dam-
age caused by static by static electricity.
1. Immediately before handling any semiconductor component or
semiconductor-equipped assembly, drain o󰀨 any electrostatic
charge on your body by touching a known earth ground. Alter-
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.
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 expo-
sure 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 classied as “anti-static” can generate
electrical charges su󰀩cient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate
electrical charges su󰀩cient 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 electri-
cally 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 replace-
ment ES devices. (Otherwise harmless motion such as the
brushing together of your clothes fabric or the lifting of your
foot from a carpeted oor can generate static electricity suf-
cient 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 1.25 cm) 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 ows onto and around both the compo-
nent 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.

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Only for training and service purposes.
IC Remove/Replacement
Some chassis circuit boards have slotted holes (oblong) through
which the IC leads are inserted and then bent at against the cir-
cuit 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 o󰀨 excess lead.
6. Replace heat sink.
Diode Removal/Replacement
1. Remove defective diode by clipping its leads as close as pos-
sible 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-o󰀨" 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 connec-
tions).
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 o󰀨
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 con-
nected to the a󰀨ected 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.

- 6 - 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
This specification is applied to the LED TV used UAX3E
chassis.
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.
3. Test method
(1) Performance: LGE TV test method followed
(2) Demanded other specification
- Safety : CE, IEC specification
- EMC : CE, IEC
4. General Specification
No Item Specication Remark
1 Market North America
2 Broadcasting system ATSC / NTSC-M, 64 & 256 QAM
3 Available Channel VHF : 02~13
UHF : 14~69
DTV : 02-69
CATV : 01~135
CADTV : 01~135
4 Receiving system Digital : ATSC, 64 & 256 QAM
Analog : NTSC-M
5 Video Input NTSC-M Rear (1EA)
6 HDMI Input UHD HDMI 1 PC / DTV format Side, Support 6Gbps
HDMI 2 PC / DTV format Side, Support 6Gbps, Support ARC
HDMI 3 PC / DTV format Rear, Support 6Gbps
HDMI 4 PC / DTV format Rear, Support 6Gbps
7 Audio Input AV Audio / DVI Audio AV and DVI use same jack ;
8 SPDIF out Optical Audio out Rear (1EA),
9 HeadPhone HeadPhone out
10 USB Input EMF, DivX HD, For SVC (download) JPEG, MP3, DivX HD

- 7 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
5. External Input Support Format
5.1. HDMI Input (PC/DTV)
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
HDMI-PC
1640*350 31.46 70.09 25.17 EGA
2720*400 31.46 70.08 28.32 DOS
3640*480 31.46 59.94 25.17 VESA(VGA)
4800*600 37.87 60.31 40 VESA(SVGA)
51024*768 48.36 60 65 VESA(XGA)
61360*768 47.71 60.01 84.75 VESA(WXGA)
71152*864 54.34 60.05 80 VESA
81280*1024 63.98 60.02 109 SXGA Support to HDMI-PC
91920*1080 67.5 60 158.4 WUXGA(Reduced
Blanking)
10 1920*1080 134.86 119.88 296.7 UDTV 2160P Not Support for FHD.
11 1920*1080 135 120 297 UDTV 2160P Not Support for FHD.
12 3840*2160 53.95 23.98 296.7 UDTV 2160P Not Support for FHD.
13 3840*2160 54 24 297 UDTV 2160P Not Support for FHD.
14 3840*2160 56.25 25 297 UDTV 2160P Not Support for FHD.
15 3840*2160 61.43 29.97 296.7 UDTV 2160P Not Support for FHD.
16 3840*2160 67.5 30 297 UDTV 2160P Not Support for FHD.
17 3840*2160 112.5 50 594 UDTV 2160P Not Support for FHD.
18 3840*2160 134.86 59.94 593.4 UDTV 2160P Not Support for FHD.
19 3840*2160 135 60 594 UDTV 2160P Not Support for FHD.
20 4096*2160 53.95 23.98 296.7 UDTV 2160P Not Support for FHD.
21 4096*2160 54 24 297 UDTV 2160P Not Support for FHD.
22 4096*2160 56.25 25 297 UDTV 2160P Not Support for FHD.
23 4096*2160 61.43 29.97 296.7 UDTV 2160P Not Support for FHD.
24 4096*2160 67.5 30 297 UDTV 2160P Not Support for FHD.
25 4096*2160 112.5 50 594 UDTV 2160P Not Support for FHD.
26 4096*2160 134.86 59.94 593.4 UDTV 2160P Not Support for FHD.
27 4096*2160 135 60 594 UDTV 2160P Not Support for FHD.
28 2560*1440 88.78 59.95 241.5 3K (UHD 60Hz models only),
Support only when UHD
DeepColor is On
29 2560*1440 182.99 119.99 497.7 3K (UHD, 8K 120Hz models
only), Support only when
UHD DeepColor is On
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
HDMI-DTV
1 640*480 31.46 59.94 25.12 SDTV 480P
2 640*480 31.5 60 25.12 SDTV 480P
3 720*480 31.47 59.94 27 SDTV 480P
4 720*480 31.5 60 27.02 SDTV 480P
5 720*576 31.25 50 27 SDTV 576P
6 1280*720 44.96 59.94 74.17 HDTV 720P

- 8 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
7 1280*720 45 60 74.25 HDTV 720P
8 1280*720 37.5 50 74.25 HDTV 720P
9 1920*1080 28.12 50 74.25 HDTV 1080I
10 1920*1080 33.72 59.94 74.17 HDTV 1080I
11 1920*1080 33.75 60 74.25 HDTV 1080I
12 1920*1080 26.97 23.97 63.29 HDTV 1080P
13 1920*1080 27 24 63.36 HDTV 1080P
14 1920*1080 33.71 29.97 79.12 HDTV 1080P
15 1920*1080 33.75 30 79.2 HDTV 1080P
16 1920*1080 56.25 50 148.5 HDTV 1080P
17 1920*1080 67.43 59.94 148.35 HDTV 1080P
18 1920*1080 67.5 60 148.5 HDTV 1080P
19 1920*1080 112.5 100 297 UDTV 2160P Not Support for FHD.
20 1920*1080 134.86 119.88 296.7 UDTV 2160P Not Support for FHD.
21 1920*1080 135 120 297 UDTV 2160P Not Support for FHD.
22 3840*2160 53.95 23.98 296.7 UDTV 2160P Not Support for FHD.
23 3840*2160 54 24 297 UDTV 2160P Not Support for FHD.
24 3840*2160 56.25 25 297 UDTV 2160P Not Support for FHD.
25 3840*2160 61.43 29.97 296.7 UDTV 2160P Not Support for FHD.
26 3840*2160 67.5 30 297 UDTV 2160P Not Support for FHD.
27 3840*2160 112.5 50 594 UDTV 2160P Not Support for FHD.
28 3840*2160 134.86 59.94 593.4 UDTV 2160P Not Support for FHD.
29 3840*2160 135 60 594 UDTV 2160P Not Support for FHD.
30 3840*2160 225 100 1188 UDTV 2160P 4K120 model
(K6Hp HDMI 3,4 port,
O20) or 8K model
31 3840*2160 269.73 119.88 1186.8 UDTV 2160P
32 3840*2160 270 120 1188 UDTV 2160P
33 4096*2160 53.95 23.98 296.7 UDTV 2160P Not Support for FHD.
34 4096*2160 54 24 297 UDTV 2160P Not Support for FHD.
35 4096*2160 56.25 25 297 UDTV 2160P Not Support for FHD.
36 4096*2160 61.43 29.97 296.7 UDTV 2160P Not Support for FHD.
37 4096*2160 67.5 30 297 UDTV 2160P Not Support for FHD.
38 4096*2160 112.5 50 594 UDTV 2160P Not Support for FHD.
39 4096*2160 134.86 59.94 593.4 UDTV 2160P Not Support for FHD.
40 4096*2160 135 60 594 UDTV 2160P Not Support for FHD.
41 4096*2160 225 100 1188 UDTV 2160P 4K120 model
(K6Hp HDMI 3,4 port,
O20) or 8K model
42 4096*2160 269.73 119.88 1186.8 UDTV 2160P
43 4096*2160 270 120 1188 UDTV 2160P
44 7680*4320 107.89 23.98 1188 8K 8K Model Only.
45 7680*4320 108 24 1188 8K 8K Model Only.
46 7680*4320 110 25 1188 8K 8K Model Only.
47 7680*4320 131.87 29.97 1188 8K 8K Model Only.
48 7680*4320 132 30 1188 8K 8K Model Only.
49 7680*4320 220 50 2376 8K 8K Model Only.
50 7680*4320 263.74 59.94 2376 8K 8K Model Only.
51 7680*4320 264 60 2376 8K 8K Model Only.

- 9 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
SOFTWARE UPDATE
1. USB
(1) Insert the USB memory Stick to the USB port
(2) Automatically detect the SW Version and show the below
message
(3) Click [YES]: initiate the download and install of the update.
(4) Click [Check Now]: move to “About This TV” page for
update
(5) TV is updating
(6) After finished the update, below Pop-up appear
(7) Click [Yes] : TV will be DC OFF -> ON
(8) After TV turned on, Check the updated SW Version and
Tool Option
2. NSU
(This Function is needed to connect to the internet)
(1) Menu -> All Settings -> Support -> Software Update
(2) Click [CHEK FOR UPDATES] : system check newest
version
(3) Click [DOWNLOAD AND INSTALL]
(4) TV is updating
(5) After finished the update, below Pop-up appear
(6) Turn OFF the TV and On. Check the updated SW Version
and Tool Option

- 10 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
BLOCK DIAGRAM
Main IC
eMMC (8GB)
CI Slot
USB1 (2.0)
OCPUSB2 (2.0)
HDMI3(2.0) HDMI2(ARC)
HDMI1(2.0)
Air/ Cable
TUNER
(T2/C/A)
TUNER
(S,S2)
DVB- S
LNB
T2/C/S/S2 H
H
-
-
NIM tuner
IF (+/-)
P_TS_OUT
P_TS_IN
MICOM
IR / KEY
USB_WIFI
X_TAL
27MHz
Sub Assy
LAN
ETHERNET
SPDIF
AV/COMPCVBS/YPbPr
SPDIF OUT
H/P AMP
RS-232
MAX323
MAIN Audio AMPI2S Out
I2C 0
Vx1 51P (8 lane)
Vx1 / EPI/ CEDS
FCIC SPI/ I2C 3
Main
PMIC
IF_S
IF
GST/MCLK/GCLK/EO/I2C 6NVRAM (256Kb)
I2C_5
I2C 1/2
EPI block
IQ (+/-), IP(+/ -)
HDMI4(2.0) (depend on model)
TS
EPI 60P (65”:8 lane, 55” ↓:6lane), CEDS 68P
Area OPT
USB_WIFI
1.5V
DDR
0.96V
Core&CP
U
3.3V
Normal
1.0V
Eth
3.5V
ST_BY
1.8V
5V
Normal
Sub
PMIC
0.96V 1.5V 3.3V 5V
1V 1.8V 3.5V_ST
0.95V 1.5V
3.3V
13V
3.3V
5V
5V
1V
1.8V
1.8V
3.5V_ST
3.5V_ST
3.3V
3.5V_ST
3.5V_ST
13V 3.5V_ST 13V
3.5V_ST
13V
3.3V 13V
13V 3.3V
13V(PANEL_VCC)
13V(PANEL_VCC)
To
Panel
From
Power
B/ D
13V
Signal flow
Supplied Voltage
In/ output Voltage
To WIFI/ BT
Combo
eMMC
CLK/DATA/STRB
48bit
DDR3 2133 x16
(512MB X 3EA)
I2C 2

- 11 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
EXPLODED VIEW (SET)
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
902
901
AR1 700
A10
400
LV1
800
530
121
HP1
HS1
120
500
540
820
HW1
200P
200A
LV2
570
ARC1

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Only for training and service purposes.
EXPLODED VIEW(MODULE)
MRC use only
* MRC : Module Repair Center
IMPORTANT NOTICE
POL(Front) Panel
Ass’y
POL(Rear) Optical Sheet
Rear Side
200PPF 200PPR
200P
200PC 200SL1 200SR1

- 13 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ASSEMBLY / DISASSEMBLY GUIDE (SET)
[Cover, Rear]
(1) Put the set facedown on the table and remove whole screw.
(2) Push the cover rear by one hand and pull it upward by another hand.
(3) Doing the step
(4) at the opposite side also.
It is easy to pull it if you put your nger in the groove.

- 14 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ASSEMBLY / DISASSEMBLY GUIDE (MODULE)
[Case Top]
(Step 1) Main, PSU, SPK, VESA, Wifi, IR disassemble
(Step 2) S-PCB Cover Shield disassemble
(Step 3) LCM reverse and disassemble Source PCB from Holder
(Step 4) Case Top Screw disassemble (side screw) and Case Top disassemble
* Rear Sliver screw 5ea
* top 7ea / side L 5ea / side R 5ea / down 7ea

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Only for training and service purposes.
(Step 5) Panel disassemble
(Step 6) Guide Panel disassemble
(Step 7) Optical Sheet disassemble (DS, Prism middle, Prism down, DP)
(Step 8) DPS, LED Fixer disassemble & Reflector Sheet disassemble
* rotate DPS (6ea) * push LED xer in back (3ea)

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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
2) Remove the protect film of Double Tape
(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.
* C/Bottom Guide Line
NG OK
* Required LED Array Quantity
Inch 55
Q’ty(EA) 3
* Finish the Attached LED Array

TROUBLE SHOOTING GUIDE
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Only for training and service purposes.

Contents of Standard Repair Process
No. Error symptom (High category) Error symptom (Mid category) Page Remarks
1
A. Video error
No video/Normal audio 1
2 No video/No audio 2
3 Picture broken/ Freezing 3
4 Color error 4
5Vertical/Horizontal bar, residual image, light
spot, external device color error 5
6
B. Power error
No power 6
7Off when on, off while viewing, power auto
on/off 7-8
8C. Audio error No audio/Normal video 9
9 Wrecked audio/discontinuation/noise 10
10
D. Function error
Remote control & Local switch checking 11
MR19 operating checking 12
11
12 Wifi operating checking 13
13 External device recognition error 14
14 E. Noise Circuit noise, mechanical noise 15
15 F. Exterior error Exterior defect 16
First of all, Check whether there is SVC Bulletin in GSCS System for these model.
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.

Normal
audio
Y
N
Move to No
video/No audio
No video
Normal audio Check Back Light
On with naked eye On Y
N
Check Power
Board
13.2V etc.
Normal
voltage
Y
N
Replace T-con/Main
Board or module
Repair Power
Board or parts
Check Power Board 13.2V output
Normal
voltage YReplace Inverter
or module
N
Repair Power
Board or parts
End
Always check & record S/W Version and White
Balance value before replacing the Main Board Replace Main Board Re-enter White Balance value
※Precaution
Established
date
Standard Repair Process
Revised date
Error
symptom A. Video error
No video/ Normal audio
☞A18☞A1
☞A18
☞A4 & A2
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, LVDS or EPI Cable, Speaker Cable, IR B/D Cable,,,)
1
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.

Normal
voltage?
Check various
voltages of Power
Board (13.2V…)
No Video/
No audio
Check and
replace
MAIN B/D
Y
Replace Power
Board and repair
parts
NEnd
Standard Repair Process
A. Video error
No video/ No audio
☞A18
Established
date
Revised date
Error
symptom
2
Copyright © 2021 LG Electronics Inc. All rights reserved.
Only for training and service purposes.