LG 75SM9900PTA User manual

P/NO : MFL71455901 (1907-REV00)
CHASSIS : UB91L
MODEL : 75SM9900PTA
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
LED TV
SERVICE MANUAL
Copyright © 2019 LG Electronics Inc. All rights reserved. Only training and service purposes.
CONFIDENTIAL

- 2 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
CONTENTS
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS ........................................................................ 3
SERVICING PRECAUTIONS ................................................................... 4
SPECIFICATION ...................................................................................... 6
SOFTWARE UPDATE ............................................................................ 10
BLOCK DIAGRAM ................................................................................. 11
EXPLODED VIEW .................................................................................. 12
DISASSEMBLY GUIDE / ASSEMBLY GUIDE ....................................... 14
TROUBLE SHOOTING GUIDE ................................................ APPENDIX

- 3 - Copyright © LG Electronics Inc. All rights reserved.
Only 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 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 precau-
tions. 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 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-effect 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 off any electrostatic
charge on your body by touching a known earth ground. Alter-
natively, obtain and wear a commercially available discharg-
ing 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 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 sol-
der removal devices not classied as “anti-static” can generate
electrical charges sufcient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate
electrical charges suf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 elec-
trically 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 mate-
rial to the chassis or circuit assembly into which the device will
be installed.
CAUTION: Be sure no power is applied to the chassis or cir-
cuit, 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 appropri-
ate 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.

- 5 - Copyright © LG Electronics Inc. All rights reserved.
Only 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 remain-
ing 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 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-off" the board. The
following guidelines and procedures should be followed when-
ever 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 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 con-
nected 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.

- 6 - Copyright © LG Electronics Inc. All rights reserved.
Only 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 UB91L
chassis.
2. Requirement for Test
Each part is tested as below without special notice
(1) Temperature: 25 °C ± 5 °C(77 °F ± 9 °F), CST: 40 °C ± 2 °C
(2) Relative Humidity: 60 % ± 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 20 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 specification
4. Model General Specification
No. Item Specication Remarks
1 Market Asia, Oceania, Africa, Middle East
2 Broadcasting system
(1) Digital TV : DVB-T/T2, DVB-C, DVB-S/S2
(2) Analogue TV : PAL B/B, PAL B/G, PAL D/K, PAL-I, SECAM
B/G, SECAM D/K, NTSC-M
Only *V* models supprot DVB-S/S2
3 Program coverage (1) ATV & DVB-T/T2 : 3,000 EA,
(2) DVB-S/S2 : 6,000 EA Only *V* models supprot DVB-S/S2
4 Receiving system Analog : Upper Heterodyne
Digital : COFDM, QAM
► DVB-T
- Guard Interval(Bitrate_Mbit/s): 1/4, 1/8, 1/16, 1/32
- Modulation : Code Rate
QPSK : 1/2, 2/3, 3/4, 5/6, 7/8
16-QAM : 1/2, 2/3, 3/4, 5/6, 7/8
64-QAM : 1/2, 2/3, 3/4, 5/6, 7/8
► DVB-T2
- Guard Interval(Bitrate_Mbit/s)
1/4, 1/8, 1/16, 1/32, 1/128, 19/128, 19/256,
- Modulation : Code Rate
QPSK : 1/2, 2/5, 2/3, 3/4, 5/6
16-QAM : 1/2, 2/5, 2/3, 3/4, 5/6
64-QAM : 1/2, 2/5, 2/3, 3/4, 5/6
256-QAM : 1/2, 2/5, 2/3, 3/4, 5/6
► DVB-C
- Symbolrate : 4.0Msymbols/s to 7.2Msymbols/s
- Modulation : 16QAM, 64-QAM, 128-QAM and 256-QAM
► DVB-S/S2
- Symbolrate
DVB-S2 (8PSK / QPSK) : 2 ~ 45Msymbol/s
DVB-S (QPSK) : 2 ~ 45Msymbol/s
- Code rate
DVB-S mode : 1/2, 2/3, 3/4, 5/6, 7/8
DVB-S2 mode: 1/2, 2/3, 3/4, 3/5, 4/5, 5/6, 8/9, 9/10
5 HDMI Input
HDMI 1 PC / DTV Format Support 4K: 12Gbps, 8K: 10Gbps
HDMI 2 PC / DTV Format Support 4K: 12Gbps, 8K: 10Gbps, Support ARC
HDMI 3 PC / DTV Format Support 4K: 12Gbps, 8K: 10Gbps
HDMI 4 PC / DTV Format Support 6Gbps, Except UM71/73/74/77/78 series
6 USB Input My Media(Movie/Photo/Music List) or For SVC UB92x : 3EA, UB93x : 2EA
7 Component Input Y/Pb/Pr Except UB92x for Middle East and Africa
8 Video Input PAL, SECAM, NTSC 4 System : PAL, SECAM, NTSC, PAL60
9 Audio Input DVI Audio, Component, AV
10 SPDIF out Optical Audio out
11 Head phone out Antenna, HDMI1, HDMI2, HDMI3, HDMI4 USB1, USB2, USB3 Except UB93x
12 Ethernet Connect

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Only training and service purposes.
5. External Input Support Format
5.1. Component input(Y, PB, PR)
No. Resolution H-freq(kHz) V-freq(Hz) Pixel clock(MHz) Proposed
1 720*480i 15.73 59.94 13.50 SDTV, DVD 480I(525I)
2 720*480i 15.75 60.00 13.51 SDTV, DVD 480I(525I)
3 720*576i 15.62 50.00 13.50 SDTV, DVD 576I(625I) 50Hz
4 720*480p 31.47 59.94 27.00 SDTV 480P
5 720*480p 31.50 60.00 27.03 SDTV 480P
6 720*576p 31.25 50.00 27.00 SDTV 576P 50Hz
7 1280*720 44.96 59.94 74.18 HDTV 720P
8 1280*720 45.00 60.00 74.25 HDTV 720P
9 1280*720 37.50 50.00 74.25 HDTV 720P 50Hz
10 1920*1080 28.12 50.00 74.25 HDTV 1080I 50Hz
11 1920*1080 33.72 59.94 74.18 HDTV 1080I
12 1920*1080 33.75 60.00 74.25 HDTV 1080I
13 1920*1080 56.25 50.00 148.50 HDTV 1080P
14 1920*1080 67.43 59.94 148.50 HDTV 1080P
15 1920*1080 67.50 60.00 148.50 HDTV 1080P
5.2. HDMI input(DTV)
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
1 640*480 31.46 59.94 25.12 SDTV 480P
2 640*480 31.5 60 25.12 SDTV 480P
3 720*480 15.73 59.94 13.5 SDTV, DVD 480I(525I)
Spec. out but display4 720*480 15.75 60 13.51 SDTV, DVD 480I(525I)
5 720*576 15.62 50 13.5 SDTV, DVD 576I(625I) 50Hz
6 720*480 31.47 59.94 27 SDTV 480P
7 720*480 31.5 60 27.02 SDTV 480P
8 720*576 31.25 50 27 SDTV 576P
9 1280*720 44.96 59.94 74.17 HDTV 720P
10 1280*720 45 60 74.25 HDTV 720P
11 1280*720 37.5 50 74.25 HDTV 720P
12 1920*1080 28.12 50 74.25 HDTV 1080I
13 1920*1080 33.72 59.94 74.17 HDTV 1080I
14 1920*1080 33.75 60 74.25 HDTV 1080I
15 1920*1080 26.97 23.97 63.29 HDTV 1080P
16 1920*1080 27 24 63.36 HDTV 1080P
17 1920*1080 33.71 29.97 79.12 HDTV 1080P
18 1920*1080 33.75 30 79.2 HDTV 1080P
19 1920*1080 56.25 50 148.5 HDTV 1080P
20 1920*1080 67.43 59.94 148.35 HDTV 1080P

- 8 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
21 1920*1080 67.5 60 148.5 HDTV 1080P
22 1920*1080 112.5 100 297 UDTV 2160P
23 1920*1080 134.86 119.88 296.7 UDTV 2160P
24 1920*1080 135 120 297 UDTV 2160P
25 3840*2160 53.95 23.98 296.7 UDTV 2160P
26 3840*2160 54 24 297 UDTV 2160P
27 3840*2160 56.25 25 297 UDTV 2160P
28 3840*2160 61.43 29.97 296.7 UDTV 2160P
29 3840*2160 67.5 30 297 UDTV 2160P
30 3840*2160 112.5 50 594 UDTV 2160P
31 3840*2160 134.86 59.94 593.4 UDTV 2160P
32 3840*2160 135 60 594 UDTV 2160P
33 3840*2160 225 100 1188 UDTV 2160P This will be added in
USERGUIDE after MR
SW update event.
34 3840*2160 270 119.88 1186.8 UDTV 2160P
35 3840*2160 270 120 1188 UDTV 2160P
36 4096*2160 53.95 23.98 296.7 UDTV 2160P
37 4096*2160 54 24 297 UDTV 2160P
38 4096*2160 56.25 25 297 UDTV 2160P
39 4096*2160 61.43 29.97 296.7 UDTV 2160P
40 4096*2160 67.5 30 297 UDTV 2160P
41 4096*2160 112.5 50 594 UDTV 2160P
42 4096*2160 134.86 59.94 593.4 UDTV 2160P
43 4096*2160 135 60 594 UDTV 2160P
44 4096*2160 225 100 1188 UDTV 2160P This will be added in
USERGUIDE after MR
SW update event.
45 4096*2160 270 119.88 1186.8 UDTV 2160P
46 4096*2160 270 120 1188 UDTV 2160P
47 7680*4320 107.89 23.98 1188 8K
8K Model Only.
48 7680*4320 108 24 1188 8K
49 7680*4320 110 25 1188 8K
50 7680*4320 131.87 29.97 1188 8K
51 7680*4320 132 30 1188 8K
52 7680*4320 220 50 2376 8K
53 7680*4320 263.74 59.94 2376 8K
54 7680*4320 264 60 2376 8K

- 9 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
5.3. HDMI Input (PC)
No. Resolution H-freq(kHz) V-freq.(kHz) Pixel clock(MHz) Proposed Remarks
1 640*350 31.46 70.09 25.17 EGA
2 720*400 31.46 70.08 28.32 DOS
3 640*480 31.46 59.94 25.17 VESA(VGA)
4 800*600 37.87 60.31 40 VESA(SVGA)
5 1024*768 48.36 60 65 VESA(XGA)
6 1360*768 47.71 60.01 84.75 VESA(WXGA)
7 1152*864 54.34 60.05 80 VESA
8 1280*1024 63.98 60.02 109 SXGA Support to HDMI-PC
9 1920*1080 67.5 60 158.4 WUXGA(Reduced Blanking)
10 1920*1080 134.86 119.88 296.7 UDTV 2160P
11 1920*1080 135 120 297 UDTV 2160P
12 3840*2160 53.95 23.98 296.7 UDTV 2160P
13 3840*2160 54 24 297 UDTV 2160P
14 3840*2160 56.25 25 297 UDTV 2160P
15 3840*2160 61.43 29.97 296.7 UDTV 2160P
16 3840*2160 67.5 30 297 UDTV 2160P
17 3840*2160 112.5 50 594 UDTV 2160P
18 3840*2160 134.86 59.94 593.4 UDTV 2160P
19 3840*2160 135 60 594 UDTV 2160P
20 4096*2160 53.95 23.98 296.7 UDTV 2160P
21 4096*2160 54 24 297 UDTV 2160P
22 4096*2160 56.25 25 297 UDTV 2160P
23 4096*2160 61.43 29.97 296.7 UDTV 2160P
24 4096*2160 67.5 30 297 UDTV 2160P
25 4096*2160 112.5 50 594 UDTV 2160P
26 4096*2160 134.86 59.94 593.4 UDTV 2160P
27 4096*2160 135 60 594 UDTV 2160P
28 2560*1440 88.78 60 241.5 3K UHD 60Hz
29 2560*1440 183 120 497.7 3K UHD 120Hz

- 10 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
SOFTWARE UPDATE
1. USB DOWNLOAD
(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 DOWNLOAD
(1) Menu → All Settings → General → About This TV
(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

- 11 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
HDMI 2.1 RX
HDMI 2.0 TX
Vx1 (Video)
Vx1 (OSD)
8K FRC
(Master)
DDR4
(1GB *2EA)
HDMI Switch
Vx1_TX MEMC
Left Image
(51P*2, 32-lane)
Right Image
(51P*2, 32-lane)
HDMI 2.0
RX
HDMI 2.1
TX
16-lane
2-lane
SoC
Vx1_RX MEMC
8K*2K
(16-lane)
LED Driver
L/Dim
(SPI)
CMD
SPI(M)
SPI(S)
HDMI 4K
Input
HDMI 8K Input
USB3 (2.0)
USB2 (2.0)
USB1 (2.0)
OCP
1.5A
OCP
1.5A
OCP
1.5A
SYS
EEPROM
eMMC
(16GB)
Return Path for 8K input
(Audio, Info, Thumbnail)
Main BoardFRC Board
USB
USB USB
HDMI1 (2.1)
HDMI2 (2.1)
HDMI3 (2.1)
HDMI4 (2.1)
TS
CVBS/SIF
Tuner
S
I
D
E
OPTIC
LAN
H/P Out
AV
Compo.
Debug
R
E A
R
Micom
DDR
(512MB
* 6EA)
WIFI/BTUSB
IR/Key/Eye
Amp * 2
(40W)
Speaker
I2S
I2C
I2C
Vx1 TX
I2S
SPI
Vx1 TX
Vx1 TX
(CVBS,L/R)
HP Amp
RS232C
Serial Flash
(8MB)
SPI
Serial Flash
(8MB)
SPI
SPI(PQ)
I2C(CMD)
SPI
SPI
Retimer
8K FRC
(Slave)
BLOCK DIAGRAM

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Only training and service purposes.
AR2 A10 A9 700
200 400
540
521
530
820
810
120
121
500 571
411
200A
570
200D
200T
550
710
910
900
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

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Only training and service purposes.
Power Board
LED
Driver
FRC Board
Main Board
HP1
HP3
HF1
HF2
HP2
HR1
HT1 HT2
SPEAKER SPEAKER
IR WIFI
HS1
HW1
LV1
LV2
EXPLODED VIEW (CABLE)

- 14 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
DISASSEMBLY GUIDE / ASSEMBLY GUIDE
1. Back Cover Disassembly Guide
(1) Lay the set on a flat Pad. And than remove Screw, Stand and Power Cord Bracket.
(2) Recognize B/C Latch Points, and ready remove B/C.
(3) Using Hera, Make space between B/C and Module. And
with the back cover raised remove B/C using Hera.
(remove direction : under → upper)
(4) Using Hera, Make space between B/C and Module. And
with the back cover raised remove B/C using Hera.
(remove direction : under → upper)
75SM90 Stand Screw : 4 Point
[ 75SM90 ]
75SM90 Holder 10 Points
75SM90 Screw 16 Points
75SM90 Latch 3 Points
B/C Assembly = Module (Holder) + B/C (Curling)
Cover Bottom+ Holder
Back Cover Curling shape
[ 75SM90 ]
Left
<Step1>
Up
Hera
<Step2>
Up
Hera
<Step3>
Up
Hera
<Step1>
Right
Up
Hera
<Step2>
Up
Hera
<Step3>
Up
Hera

- 15 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
(5) For remove Top Latch, with the back cover raised, remove B/C using Hera. (remove direction : outside → inside)
(6) Two people grasp B/C, and remove B/C. (Grasp position : 600~800mm)
(7) B/C Handling is refer to B/C Handling Guide.
Top(Left)
Up
Hera
Up
Hera
Hera Hera
Up
Up
Top(Right)
<Step1> <Step2>

- 16 - Copyright © LG Electronics Inc. All rights reserved.
Only training and service purposes.
2. Back Cover Handling Guide
▪ One person B/C Handling Guide ▪ Two person B/C Handling Guide (OK)
▪ Two people Handling Guide (NG)
-1 Person, 2 Hands Grasp :
Shoulder width 600mm
(UF85 Applied method)
-Stand and Top middle
Grasp.
-2 People Grasp : Long side
shoulder width 600~800mm
- 2 people set up : 4-corner Handling

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Only training and service purposes.
3. Back Cover Assembly Guide
(1) After set B/C above Module, Push Latch Point in B/C Bending. (Push slope direction of B/C for preventing transform)
(2) Confirm Latch Assmble(If Latch is not assemble, Gap and lifting are made.)
* Latch Point refer to next page.
(3)Assemble the Screw of B/C and Stand.
NG
Ok
Ok
B/C-Module Gap
75SM90 Stand Screw : 4 Point
75SM90 Holder 10 Points
75SM90 Screw 16 Points
75SM90 Latch 3 Points

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Only training and service purposes.
4. Set Disassembly Guide
(1) Remove all screw of bottom bracket and IR/Wifi Cable at P4000.
(2) Remove Brackets with IR, Wifi/BT Assy.
(3) Remove all sort of cable.
222 2
2Screw point
2
CN101
CN6
P203(14P)
P202
P202(15P)
NC
P202
P401
P7603
P402
P700
P1401
P1400
P1
P1100
P5901/2/3
CN102 P7601
CN4CN3CN2CN1
P501
P500
P503
P502
2
1
4
3
2143
P7602
(remove cables from the supporter holder)

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Only training and service purposes.
(4) Screw disassembly
(5) Speaker disassembly
(6) Stand Supporter disassembly
2Screw point
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2Screw point
2
2
2
2

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Only training and service purposes.
1. DISASSEMBLY GUIDE
(1) Disassemble of Cover Shield L,R.
* Disassemble the Screws(6/6 EA(L/R)) and
T-Con FFC.
* Disassemble the source PCB from the guide.
(Remove bridge FFC tape 2 EA before
disassembly)
(2) Disassemble of Guide panel screw
* Disassemble Pad of 4Corner
* Reuse it when assemble it.
* Disassemble the Screws (Except for 5 screws)
(3) Disassemble of Case Top screws.
*
bottom side screws 6 EA
DISASSEMBLY GUIDE / ASSEMBLY GUIDE (MODULE)