LED TV
SERVICE MANUAL
CHASSIS : UJ22A
MODEL : 55QNED80SQA
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
P/NO : MFL71911602 (2202-REV00)
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 © 2022 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 .................................................................................. 12
EXPLODED VIEW ................................................................................... 13
ASSEMBLY / 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 UJ22A (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 Market Brazil / South&Central AMERICA
2 Broadcasting system Digital : SBTVD
Digital : DVB-T, DVB-T2
3 Available Channel BAND NTSC
VHF 2 ~ 13
UHF 14 ~ 69
DTV 2 ~ 69
CATV 1 ~ 135
4 Receiving system Digital : ISDB-T
Analog :NTSC-M/PAL-N/PAL-M
5 HDMI Input HDMI 1 PC / DTV Format Support 6Gbps
HDMI 2 PC / DTV Format Support 6Gbps, Support ARC
HDMI 3 PC / DTV Format Support 6Gbps, Support ARC
HDMI 4 PC / DTV Format Support 6Gbps
6 Audio out SPDIF out Rear
7 USB Input(3EA) EMF, DivX HD, For SVC (download) JPEG, MP3, DivX HD
-6- 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
PC
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,
Not Support for FHD.
9 1920*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 (UHD 60Hz models only),
Support only when UHD
DeepColor is On
28 2560*1440 88.78 59.95 241.5 3K (UHD, 8K 120Hz models
29 2560*1440 182.99 119.99 497.7 3K only), Support only when
UHD DeepColor is On
-7- 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
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
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 (LM21U
31 3840*2160 269.73 119.88 1186.8 UDTV 2160P HDMI port, O20N) or 8K
model
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.
-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
DTV
41 4096*2160 225 100 1188 UDTV 2160P 4K120 model (LM21U
42 4096*2160 269.73 119.88 1186.8 UDTV 2160P HDMI port, O20N) or 8K
model
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) Plug in the USB to the TV
(2) If there are update-able files in the USB, the TV would ask that the user want to process the SW upper version update.
(3) Click “Yes” button : Start Update
(4) Click “Check Now” : Go to SW Update menu for monitoring
(5) TV has been starting SW update
(6) After finishing the update, it will show a pop-up below the picture
(7) Click “Yes” : Tv will be turn off and on itself
- 10 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
2. NSU
(This Function is needed to connect to the internet)
Case 1) Auto Update On Case 2) NOT Allow Automatic Updates Toggle Item
(1) Go to Menu -> All Settings -> Support -> Software Update, (1) Go to Menu -> All Settings -> Support -> Software Update
then check Auto update is turned on.
(2) After the update complete, the user can check a pop-up (2) If it found upper version SW than the TV SW version, TV
below the picture, which indicated update is complete and would show a pop-up like below the picture.
the new version will be applied after the TV turn off and on. “The latest version of the SW is available for your TV. Do
you want to update now”
(3) If the user want to check the process of updating (3) [Yes] : update starts.
[Menu -> All Settings -> Support -> Software Update] [No] : Close the pop-up, check out later
(4) If the user started the update, the TV shows a pop-up
below the picture.
(5) [CHECK NOW] : Just start the update
[Close] : Close the pop-up
(4) If it needs to cancel the update, click “cancel update” button
(5) [“No”] : update continue
[“Yes”] : update cancel
- 11 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
0.96V 1.5V 3.3V 5V
13V 0.95V 3.5V_ST 1.2V 13V 3.3V 13V 5V
Core DDR Normal Normal X_TAL
3.5V_ST 2.5V 27MHz
0.95V 1.2V 3.3V 1V 1.8V
1V 2.5V
1.8V 3.5V_ST 5V
13V 3.3V 3.5V 3.5V_ST 2.5V P_TS_IN
1.0V 1.8V 13V
ST_BY VPP DDR4 2400 x16
CPU 48bit P_TS_OUT CI Slot
(512MB X 3EA)
13V
EPI block 13V(PANEL_VCC) 13V(PANEL_VCC) SMARTCARD A-CAS 3.5V_ST
Sub Main I2C_5 NVRAM (256Kb)
PMIC PMIC GST/MCLK/GCLK/EO/I2C 6
MICOM eMMC 3.3V
eMMC (8GB)
CLK/DATA/STRB
5V 1.8V
Vx1 / EPI/ CEDS
EPI 60P (65”:8 lane, 55”↓:6lane), CEDS 68P
USB1 (2.0)
FCIC SPI/ I2C 3 OCP
Vx1 51P (8 lane) Main IC USB2 (2.0) From
- 12 -
HDMI1(2.0) Power
To 13V 3.3V
I2S Out HDMI2(ARC)
Panel MAIN Audio AMP B/D
I2C 0 HDMI3(2.0)
USB_WIFI Area OPT
IF
IF (+/-)
Copyright ©
BLOCK DIAGRAM
IF_S IQ (+/-), IP(+/-)
3.3V
tuner
TS
Signal flow
TUNER TUNER
SPDIF OUT
USB_WIFI
ETHERNET
CVBS/YPbPr
I2C 1/2
H-
Supplied Voltage
(S,S2) (T2/C/A)
3.5V_ST I2C 2
In/output Voltage
LNB 13V
AMP
Air/
T2/C/S/S2 H-NIM
DVB-S
MAX323
3.5V_ST Cable
Only for training and service purposes.
IR / KEY LAN
AV
H/P
SPDIF
RS-232
To WIFI/BT
Sub
LG Electronics Inc. All rights reserved.
Assy Combo
Area OPT
EXPLODED VIEW (SET)
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
LV2
LV1
120
900
HW1
540
570
HS1
HP1
500
530
411
800
121
200A
700
200
A10
AR2
- 13 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
ASSEMBLY / DISASSEMBLY GUIDE (SET)
* Disassemble the back cover after wearing gloves.
[Back Cover Disassembly Guide]
※ Preparation Tool
- Driver
- Plastic scraper
- Gloves
(1) Place the set on the flat pad and remove the stand.
2Pole Set
(2) Remove the screw assembled on the B/C. (Refer to Working Guide through WISS system)
- 14 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(3) Separate the left side of B/C from the module latch by using ‘Plastic scraper'.
(4) Hold B/C at the lower left and lower center of B/C and lift slightly.
(But, the height raised by B/C shall not be more than 10cm.)
not be more than 10cm
- 15 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(5-1) Slightly lift the B/C to separate it from the Latch area on the right side of the module. And move it to
the right. (Raise B/C to a height that is not interfering with the Vertical AV bracket.)
1step
Raise B/C to a height that is not interfering
with the Vertical AV bracket.
(5-2) Slightly lift the B/C to separate it from the module upper latch area. And move it up.
- 16 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(6) Hold the bottom of B/C and lift the b/c to remove it.
Precautions : Hold the upper and lower parts when handling B/C.
-> Top corner dent occurs if the upper and lower parts of B/C is not held.
(Refer to detailed B/C Handling Guide)
- 17 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
* Assemble the back cover after wearing gloves.
[Back Cover Assembly Guide]
(1) Hold the bottom of B/C and Put it on the module.
Precautions : Hold the upper and lower parts when handling B/C.
-> Top corner dent occurs if the upper and lower parts of B/C is not held.
(Refer to detailed B/C Handling Guide)
(2) Check that B/C is properly placed on the module and cover the b/c.
- 18 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
(3) After assembling the screw, check it for normal assembly and appearance.
B/C Latch Assembly Position & Guide
: Latch (Holder) Position
55”
NG OK
Don’t press B/C inner area Press the end of B/C
(Issue -> B/C Dent) where Latch is located.
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Only for training and service purposes.
* Handling Guide the back cover after wearing gloves.
[Back Cover Handling Guide]
▪ Two people Handling Guide - OK
Precautions :
Hold the upper and lower parts
when handling B/C.
-> Top corner dent occurs
if the upper and lower parts of B/C
is not held.
Hold the upper and lower parts
▪ scene of b/c dent occurrence.
When turning B/C for line input after holding the back of b/c, a dent occurs when tilting in a
one-sided direction.
- 20 - Copyright © LG Electronics Inc. All rights reserved.
Only for training and service purposes.
* Unpacking Guide the back cover after wearing gloves.
[Back Cover Unpacking Guide_B/C Line Input]
Step 1. Lift B/C from Box Step 3. Completely lift B/C from Box
Worker 2 Worker 1
Line direction
Worker 1 : Hold the upper and lower parts
Worker 1 : Back Cover Top Handling
Worker 1 : upward lift
Step 2. Lift B/C from Box
: Hold the upper and lower parts when using a courtesy
car
Worker 1 : Lift vertically and hold
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Only for training and service purposes.
Step 4. B/C Assembly #1
B/C Latch Assembly Position & Guide
: Latch (Holder) Position
55”
Worker 1 : Turn around
Worker 2 : Prepare to receive b/c.
Step 5. B/C Assembly #2
NG
Don’t press B/C inner area
(Issue -> B/C Dent)
Worker 1 : Give B/C to Worker 2
Worker 2 : Hold the top of B/C
Step 6. B/C Assembly #3
Worker 2 Worker 1
OK
Press the end of B/C
where Latch is located.
Worker 1 /Worker 2 : Check that B/C is properly placed
on the module and cover the b/c.
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Only for training and service purposes.
TROUBLE SHOOTING GUIDE
Copyright © 2022 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 Picture broken/ Freezing 3
A. Video error
4 Color error 4
Vertical/Horizontal bar, residual image, light spot,
5 5
external device color error
6 No power 6
7 B. Power error Off when on, off while viewing, power auto on/off 7
8 Off when on, off while viewing, power auto on/off 8
9 No audio/Normal video 9
C. Audio error
10 Wrecked audio/discontinuation/noise 10
11 Remote control & Local switch checking 11
12 Magic Remote control operating checking 12
13 D. Function error WiFi operating checking 13
14 External device recognition error 14
15 Voice Recognition Function Error 15
16 E. Noise Circuit noise, mechanical noise 16
17 F. Exterior error Exterior defect 17
First of all, Check whether there is SVC Bulletin in GSCS System for these model.
Copyright © 2022 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 1/17
First of all, Check whether all of cables between board is inserted properly or not.
(Main B/D↔ Power B/D, Each Cable for Panel, Speaker Cable, IR B/D Cable,,,)
☞A1 ☞A9
No video Normal Y Check Back Light Y Check Power board Y Replace T-con/Main
Normal
On
Normal audio audio On with naked eye 12V etc. voltage Board or module
N N N
Move to No ☞A9 Check Power Board VLED output Repair Power
video/No audio Board or parts
Y LED Y
Normal Error Check LED Driver Replace LED
Driver B’D
voltage Board by LED indicator Driver BD
error
N N
Repair Power Replace Module End
End
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
Copyright © 2022 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 2/17
☞A9
Check various Y Check and
No Video/ Normal
voltages of Power replace
No audio voltage?
Board (12V…) MAIN B/D
N End
Replace Power
Board and repair
parts
Copyright © 2022 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 3/17
. By using Digital signal level meter
☞ A3
. By using Diagnostics menu on OSD
Check RF Signal level ( Advanced→ Channels→ Channel Tuning→ Manual Tuning → Check the Signal )
- Signal strength (Normal : over 50%)
- Signal Quality (Normal: over 50%)
Check whether other equipments have problem or not.
Normal Y
(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 Tuner Y
Connection Close
1. Reconnection Picture? S/W Version Bulletin? soldering
2. Install Booster
Y N
N
S/W Upgrade
Normal N Contact with signal distributor
Picture? or broadcaster (Cable or Air)
Normal N
Y Picture? Replace
Main B/D
Y
Close
Close
Copyright © 2022 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 4/17
☞ A7
☞A6 ※ Check and
replace Link
Check color by input Y Cable Y Y
Color Color Color
-External Input (EPI or Vx1 Replace Main B/D Replace module
error? error? error?
-HDMI Cable) and
N contact N N
condition
End
Check error
color input mode
☞A20
External Input/ Check external External Y
Check Test pattern Component device and device/Cable Replace Main/T-con B/D
error cable normal
N
Request repair
for external
device/cable
N
Check external External Y
HDMI
device and device/Cable Replace Main/T-con B/D
error
cable normal
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error A. Video error date
symptom Vertical / Horizontal bar, residual image,
light spot, external device color error Revised date 5/17
Vertical/Horizontal bar, residual image, light spot Replace
Module
☞A6
☞ A7 N
Check color condition
Check external Check and
by input Screen Y Y Screen N Screen
device connection Normal? replace Link Replace Main/T-con B/D
-External Input normal? normal? normal?
condition Cable
-HDMI For LGD panel
N Y Y
N
Replace Main B/D
☞A20 Replace Request repair End End
module for external For other panel
Check Test pattern device
External device screen error-Color error
Check screen
Check S/W Version N condition by input External Connect other external
Check
-External Input Input device and cable
version
-Component error (Check normal operation of N Replace
-HDMI/DVI Screen
External Input, Component, Main/T-con
Y normal?
RGB and HDMI/DVI by B/D
Component connecting Jig, pattern
error Y
S/W Upgrade Generator ,Set-top Box etc.
Request repair for
external device
Connect other external Y
Normal N
device and cable
screen? Replace
HDMI/ (Check normal operation of Screen N
External Input, Component, Main /T-con
Y DVI normal?
RGB and HDMI/DVI by B/D
connecting Jig, pattern
Generator ,Set-top Box etc.
End
Copyright © 2022 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 6/17
☞A8 ☞A9
Y DC Power on N Y
Check front Power Normal Check Power Replace
by pressing Power Key OK?
Power Indicator LED On? operation? On ‘”High” Power B/D
On Remote control
. Stand-By: Red or Turn On
N Y N
. Operating: Turn Off
Check Power cord Replace Main B/D
was inserted properly ☞A9
Measure voltage of each
output of Power B/D
N
Normal?
Y Y
Normal Y
Replace Main B/D
voltage?
Normal
Close Check Power ST-BY 7.8V Y
voltage? N
☞A9 Replace Power B/D
N
Replace Power
B/D
Copyright © 2022 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 7/17
Check Power outlet
☞A11
N Check Power Off CPU Y
Check A/C cord Error? Replace Main B/D Normal? End
Mode Abnormal
N
Check for all 2- phase
Y NO_ Replace Power B/D
power out
POLLING
Fix A/C cord & Power
Outlet and check ☞A9
each 2 phase out (If Power Off mode
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
Copyright © 2022 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 8/17
* Please refer to the all cases which can be displayed on power off mode.
Power Off list Explanation Action contents
Power off when TV is not turned off during a certain time
KEYTIMEOUT RESULT : micom force to trigger TV power off. Check & Change Main B/D
CONDITION : When pressing power key while power on/off status, CPU does not response within 8 seconds
Almost the same as Power Off by KEYTIMEOUT. If there is no vaild communication
Bet ween CPU and MICOM for more than 5 seconds, the MICOM switcheds off PSU and
1SEC Power OFF Check & Change Main B/D
Records. Power off by 1SEC Power off. In this case, we don’t have information where the
malfunction exactly occurred. But in in indicates that CPU had stopped and rebooted.
In case of AC Off (It is normal when the power cord is unplugged.) Normal
ACDET
If there are many ACDETs connected, Power Board is defective Check & Change Power B/D
Power off by unstable AC power detect.
RESULT : micom check the stable power.
5V MNT Check & Change Power B/D
CONDITION : When AC on or DC on, stabilization check routine (Power Detect High
Check) fail after multi power on.
CPUABNORMAL If the CPU attempts to reset in case of abnormal operation and Shut Down in case of failure. Check & Change Main B/D
Power off when receiving no ack. RESULT : TV power off/on (Reboot)
NO POLING Check & Change Main B/D
CONDITION : There is no I2C response from CPU for 15 seconds.
CPUCMD Power off by main SoC command. Check & Change Main B/D
INV_ERROR Power off by module error (OLED), CONDITION : OLED Module send signal to micom Check & Change OLED Module
ONRF_FAIL RESULT : Reboot, CONDITION : OLED module compensation is running but fails. Check & Change OLED Module
PNWASHFAIL Power off by panel noise wash function fail case. Check & Change OLED Module
RESET When Micom is reset by AC Off
KEY Power off by Local key
OFFTIMER Power off by Off timer
SLEEPTIMER Power off by sleep timer
NOSIG Power off by No Signal
FANSTOP Power off by FAN operation stopped
INSTOP Power off by Instop Key
AUTO OFF Power off by auto off function
RESREC Power off by reserved recording
Normal Case
RECEND Power off when recording stops
SWDOWN Reboot by SW down load function
UNKNOWN No meaning (same as initial value)
COMP_END OLED threshold voltage degradation(Compensation) completes.
PNWASHDONE Power off by panel noise wash function complited. (OLED)
POWER_OFF_BY_FAN_
Power off by FAN operation status.
CTRL_ERROR
POWER_OFF_BY_TEMPER
Power off by Temperature Sensor operation status
ATURE_SENSOR_ERROR
8
Copyright © 2022 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 9/17
☞A12
☞A13+A9
Check user N Y
No audio Check audio 20V Normal
menu > Off
Screen normal of Power Board voltage
Speaker off
Y N
Cancel OFF Replace Power Board and repair parts
Check Speaker N
Disconnection Replace MAIN Board End
disconnection
Y
Replace Speaker
Copyright © 2022 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 10/17
→ abnormal audio/discontinuation/noise is same after “Check input signal” compared to No audio
Wrecked audio/
☞A13+A9
Check and replace
Discontinuation/ Check audio
speaker and
Noise for B+ Voltage (20V)
connector
Check input all audio
signal Y
Signal
-RF
normal? Wrecked audio/ Y
-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
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error D. Function error date
symptom
Remote control & Local switch checking Revised date 11/17
1. Remote control(R/C) operating error Replace
Main B/D
☞A14 ☞A14 ☞A14
Check & Repair N Y Y
Check R/C itself Normal Y Normal Check B+3.5V Normal Check IR Normal
operating? Cable connection operating? Voltage? Signal?
Operation On Main B/D Output signal
Connector solder
N
Y N N
☞A9
Check R/C Operating Check & Replace Check 3.5v on Power B/D Repair/Replace
Close
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
Explain the customer operating? Close
cause is interference
from light in room. N
Replace R/C
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error D. Function error date
symptom
Magic Remote control operating checking Revised date 12/17
2. Magic Remote control operating error
☞A4
N N Turn off/on the
Check the RF Receiver Check MR22 Normal Y Press the Is show ok
ver is “00.00”? operating? message? set and press
INSTART menu itself Operation wheel
the wheel
N Y
Y
☞A15
Check & Replace Close
Check & Repair Battery of MR22
RF assy
connection
Normal Y
☞A4 operating? Close
Is show ok N Press the back
RF Receiver ver N N message? key about 5sec
is “00.00”? Close
Y
Replace
Y MR22
Close
Down load the Firmware
* If you conduct the loop at 3times, change the MR22.
* INSTART MENU
14.RF Remote control Test
3. Firmware download
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error D. Function error date
symptom
WiFi operating checking Revised date 13/17
3. WiFi operating error
☞A4 ☞A15
Wi-Fi Mac N Check the WiFi wafer Replace
Check the Normal N
value
INSTART menu +3.5V_WiFi Voltage? Main B/D
is “NG”?
Y
☞A15 Y
Close
Check & Repair
Wifi cable
connection
☞A4
Wi-Fi Mac N
value Close
is “NG”?
Y
Change the Wifi
assy
Copyright © 2022 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 14/17
Check technical
Check Y N External Input
Signal information Technical
input And Component Replace Main B/D
input? - Fix information information?
Recognition error
signal
- S/W Version
N Y
HDMI/
Check and fix DVI, Optical
Fix in Replace Main B/D
external device/cable Recognition
accordance
error
with technical
information
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process
Established
Error D. Function error date
symptom
Voice Recognition Function Error Revised date 15/17
☞A15
Check Voice Funcion Check
Network Y Y
Check network Recognition Function Is On In Sub Ass’y
Connected?
in menu menu? Cable
N
N
Make the
Connect network function ‘on’
Close Close
Cable Change Voice
Connection Y Recognition Change Main B/D
Is OK? Ass’y
N
Re-connect Close
Cable Close
Close
Copyright © 2022 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 16/17
Identify Circuit Check location
Replace PSU
nose type noise of noise
Mechanical Check location
noise of 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 in cabinet, refer to the KMS fix information and
“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)
Copyright © 2022 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 17/17
Zoom part with Module
Replace module
exterior damage damage
Cabinet
Replace cabinet
damage
Remote
control Replace remote control
damage
Stand
Replace stand
dent
Copyright © 2022 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 Back Light On 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 (Vx1/EPI) reconnection
7 A. Video error_ Color error A7
condition
Check Cable (1) ~ (2) A-1/11 ~ 2/11
Exchange Main Board (1) ~ (3) A-3/11 ~ 5/11
8 Defected Type caused by T-Con/ Exchange Module (1) ~ (3) A-6/11 ~ 8/11
Module
Exchange T-Con (1) ~ (2) A-9/11 ~ 10/11
Exchange Power Board(PSU) A-11/11
Continue to the next page
Copyright © 2022 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
9 Check front display LED(Power Indicator) A8
10 B. Power error_ No power Check power input Voltage & ST-BY A9
11 Error check by LED Indicator A10
12 Checking method in menu when there is no audio A12
C. Audio error_ No audio/Normal
video Voltage and speaker checking method when there is
13 A13
no audio
14 Remote control operation checking method A14
D. Function error
15 Magic Remote/WiFi operation checking method A15
16 How to use the Service remote control A16-A18
17 E. Etc Check items after Main B/D replacement A19
18 Adjustment Test pattern - ADJ Key A20
Copyright © 2022 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 Back Light On with naked eye A1
date
If the Black light LED assemble is ‘OK’, you can see the lights on each points.
A1
Copyright © 2022 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 method
1. Press the ADJ button on the remote control for adjustment.
2. Enter into White Balance.
3. After recording the R, G, B (GAIN, Cut) value of Color Temp (Cool/Medium/Warm),
re-enter the value after replacing the MAIN BOARD.
A2
Copyright © 2022 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 input signal strength checking method A3
date
All settings Programmes
Programme Tuning & settings Manual Tuning
When the signal is strong,
use the attenuator
(-10dB, -15dB, -20dB etc.)
A3
Copyright © 2022 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 Version checking method A4
date
1. Checking method for remote control for adjustment
Version
Press the IN-START with the remote
control for adjustment
A4
Copyright © 2022 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 checking part Revised
Content A5
date
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 © 2022 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 A6
date
As the part connecting to the external input, check
the screen condition by signal
A6
Copyright © 2022 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(CEDS) reconnection condition A7
date
Check the contact condition of the Link Cable, especially dust or mis insertion.
A7
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Image error) #1 Check for poor cable contact
Symptom
Item Cause Symptom Image
Name
CABLE Color smear Poor broken pin of FFC cable
Color is Excessive due to FFC Cable
CABLE R Color Excessive
Contact.
screen is dark due to poor contact due
CABLE Screen darkness to disconnection of the FFC cable pin.
G color transient due to poor FFC cable
CABLE G Color Excessive connection
A - 1/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Image error) #2 Check for poor cable contact
Symptom
Item Cause Symptom Image
Name
CABLE Color spread LVDS cable connection problem
CABLE Color spread LVDS cable connection problem
CABLE Color spread LVDS cable connection problem
Due to foreign substance withi nLVDS
CABLE Screen stop cable PIN
A - 2/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Main) #3 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
Main Screen noise Bit noise from horizontal screen
Broken screen due to
Main Screen noise
Main IC problem
Main Dark picture Dark left-side screen
Top/bottom screen part
Main Broken picture
Picture problem due to tuner
Inner side quality problem
A - 3/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Main) #4 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
Main Broken screen Broken screen in a horizontal manner
Main Screen spread Screen corner appears blurry
Main Color Spread Color spread on the screen
Main Blurry Screen Blurry picture on the screen
A - 4/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Main) #5 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
No problem at the initial stage,
Main Broken picture G-color spread after 10 minutes
Right-side
Main
Screen Right-side screen problem
problem
LG logo
Main Screen picture spread problem
Screen problem
No problem at the initial stage.
Right-side
Main During Heat run, right-side picture
picture problem
problem
A - 5/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Module) #6 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
Isometric Isometric horizontal bars occur
MODULE
Horizontal Bar throughout the screen
MODULE Internal matter BLU internal foreign matter inflow
MODULE Image broken 6 block image broken
MODULE Image broken Screen sync signal broken
A - 6/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Module) #7 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
Internal damage and image breakage
MODULE Image broken
due to external impact
Bend on the Bending due to lateral external impact
MODULE
screen and internal bending of BLU
Vertical spreading on cube screen in no
MODULE Vertical smear
signal
MODULE Over color Screen contour part brightly Over color
A - 7/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(Module) #8 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
MODULE Vertical bar Center Vertical Bar
MODULE Screen darkness Center of the screen 1 block dark
MODULE Vertical bar Center Vertical Bar
Darkness at the
MODULE bottom of the MODULE internal BLU breakage
screen
A - 8/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(T-Con) #9 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
screen lower T-Con is defective and the picture below
T-CON
image broken the screen is broken
screen lower T-Con is defective and the picture below
T-CON
image broken the screen is broken
screen lower T-Con is defective and the picture below
T-CON
image broken the screen is broken
screen lower T-Con is defective and the picture below
T-CON
image broken the screen is broken
A - 9/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix. Examples of Symptoms(T-Con) #10 Check parts by symptom
Symptom
Item Cause Symptom Image
Name
T-CON Wafer Locking The strength is
T-CON Image Broken
weak and cable contact failure occurs
Darkness at the Initial normal operation,
T-CON
top of the screen upper darkness during heat run
The entire screen is dark and bit noise
T-CON Image Broken
occurs
The entire screen is dark and bit noise
T-CON Image Broken
occurs
A - 10/11
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Appendix : Exchange Power Board (PSU) #11 Check parts by symptom
No Light No Power On
A - 11/11
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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 A8
date
ST-BY condition: On or Off
Power ON condition: Turn Off
A8
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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 A9
date
SET Model Power P/N, Name
55QNED80/81 EAY65895412, LGP55-21UL6
Power Check Sequence
1. AC input Check : SK100 (100~240Vac)
2. PWR-ON Check : P201, 3 pin
- SET On : above 3V
- SET St-by : 0V
3. 13.2V DC Check : P201, 6~10 pin
- SET On : 13.2V
- SET St-by : 7.8V
4. DRV-ON Check : P201, 13 pin
- SET On : above 3V
- SET St-by : 0V
5. LED voltage Check : P801, 8 pin & P802, 1 pin
All condition meets, Power Board OK. SK100 (AC input)
A9
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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 A11
date
Entry method
1. Press the IN-START button of the remote control for adjustment.
2. Check the entry into adjustment item 3.
A11
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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 A12
date
Checking method
1. Press the Setting button on the remote control.
2. Select the Sound function of the Menu.
3. Select the Sound Out.
4. Select TV Speaker.
A12
Copyright © 2022 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 A13
when there is no audio date
[55QNED80/81]
①
②
③
1 SPK_R-FT
2 SPK_R+FT
③ 3 SPK_L-FT
4 SPK_L+FT
Checking order when there is no audio
1. Check the contact condition of or 13.2V connector of Main Board.
2. Measure the 13.2V 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.
A13
Copyright © 2022 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 A14
date
① Pin Pin name
1 +3.5V_WIFI
IR & EYE Sensor 2 WIFI_DM
3 WIFI_DP
4 GND
5 WOL/WIFI_POWER_ON
6 +3.5V_WIFI
7 WIFI_SUSPEND/RESUME
8 GND
9 COMBO_RESET
10 BT_WAKEUP_HOST
11 GND
② 12 +3.5V_WIFI
13 N.C
Pin #25 14 N.C
15 N.C
③
~
16 EYE_SDA
17 EYE_SCL
Pin #1 18 GND
19 IR
20 LED_R
21 GND
Checking order to check remote control 22 +3.5V_ST
23 KEY2
24 MIC_DATA
25 MIC_CLK
Checking order
1. Check IR cable condition between IR & Main board.(Check picture number① and ②.)
2. Check the standby 3.5V on the terminal. (③)
A14
Copyright © 2022 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 Magic Remote/WiFi operation checking method A15
date
Pin Pin name
1 +3.5V_WIFI
① Wifi & BT Front 2 WIFI_DM
3 WIFI_DP
4 GND
5 WOL/WIFI_POWER_ON
6 +3.5V_WIFI
7 WIFI_SUSPEND/RESUME
8 GND
9 COMBO_RESET
10 BT_WAKEUP_HOST
11 GND
Wifi & BT Rear ② 12 +3.5V_WIFI
13 N.C
Pin #25 14 N.C
15 N.C
③
~
16 EYE_SDA
17 EYE_SCL
Pin #1 18 GND
19 IR
20 LED_R
21 GND
22 +3.5V_ST
23 KEY2
24 MIC_DATA
25 MIC_CLK
Checking order to check motion remote/wifi
Checking order
1. Check BT/Wifi cable condition between BT/Wifi assy & Main board.
2. Check the 3.5V on the terminal 1 pin.
A15
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Standard Repair Process Detail Technical Manual
Error Established
symptom E. Etc date
Revised
Content How to use the Service remote control A16
date
1. How to access the remote control
0 4 1 3
0 4 1 3
A16
Copyright © 2022 LG Electronics Inc. All rights reserved.
Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom E. Etc date
Revised
Content How to use the Service remote control A17
date
2. Remote control part definition
POWER Power On/Off
[ETC] Each time pressing the KEY button, Mode gets changed to ETC and P-ONLY each time
ETC (Added Function) All KEY function [PIP PR-][PIP PR+][SWAP]
[PIP INPUT][DVI] KEY Function
Changed to factory mode
P-ONLY (Added
Function)
All KEY function &[INFO][STILL][HDMI HOT][USB HOT][HDMI4] KEY Action
INPUT Change to the external device mode
ARC Change in the order of 16:9=>Zoom1=>Zoom2=>Cinema Zoom=>Aucto Screen=>4:3=>16:9
Changes in the order of Bright Picture=>Easy Picture=>Cinema=>Spots=>Game=>
PSM
Custom PIcture1=>Custom Picture2=>Bright Picture
SSM (Added Function) Standard(user)=>music=>cinema=>sports=>game=>standard(user)
PIP Picture In Picture is activated
TEXT Access to the Power Only mode
CAP Broadcasting caption(on/off)
MPX Stereo mode (mono, stereo, foreign language) access
Used when in factory mode
Simplink (Added
Access to the Simplink-connected device
Function)
Digital EYE function ON/OFF
EYE
For some Model, access to the Test Pattern
TILT Used for screen tilting change (Access to the old PDP control mode)
A17
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Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom E. Etc date
Revised
Content How to use the Service remote control A18
date
B-TOOTH
Connected to Blue-Tooth
(Added function)
Model Nam ex) 42PG60D-NA Current Model Name S/W Version ex)
IN-START V03.11.0 Current S/W version
MICOM Version ex) V3.05.0 current Mi-Com version UTT ex) User TV total usage time
POWER OFF STATUS ex) Shows power-off status
ADJ
Test Pattern (Off=>White=>Red=>Green=>Blue=>Black=>Pattern=>Off) Change
X-STUDIO (Added function) HDD,USB, external device’s HDD screen is activated
MENU User function gets activated
EXIT Exit from the current mode
TIME SHIFT (Added
Moves forward/backward of recorded contents
function)
MUTE Mute function (0 Volume)
IN-STOP SET to factory mode
VOL + - Volume Up/Down
CH + - Channel Up/Down
AV1,2,3 (Added function) Connects to external input 1,2,3
COMP1,2 (Added function) Connects to Component 1,2
HDMI1,2,3,4
Connects to HDMI 1,2,3,4
(Add function)
DVI (Add function) Connects to DVI
A18
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Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom E. Etc date
Revised
Content Check items after Main B/D replacement A19
date
Check items afer Main B/D(Model Number D/L, White Balance)
1. Press the Service remote control instart Key.
No.7 Select Model Number D/L
- Key in the model name and serial number
after checking the ID label on the back cover.
2. Press the Service remote control ADJ Key.
No.13 Select White Balance
- Record the R, G, B (GAIN, Cut) value of the
color temperature before main board
replacement.
After replacing the main board, key in the
recorded value.
A19
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Only for training and service purposes.
Standard Repair Process Detail Technical Manual
Error Established
symptom E. Etc date
Revised
Content Adjustment Test pattern - ADJ Key A20
date
P-ONLY HDMI HOT(Yellow button) CH ‘+’ or ‘-’
You can view 11 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!)
A20
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Only for training and service purposes.
