LG 27UL850 User manual

Internal Use Only
CHASSIS :
MODEL :
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
SERVICE MANUAL
LED MONITOR
SERVICE MANUAL
LM8BA
27UL850
27BL85U
P/NO : MFL69413817(1811-REV00)

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS ........................................................................ 3
SPECIFICATION ....................................................................................... 4
Firmware Upgrade Method ............................................................... 8
TROUBLE SHOOTING GUIDE .............................................................. 19
BLOCK DIAGRAM ................................................................................. 14
EXPLODED VIEW .................................................................................. 15
DISASSEMBLY ...................................................................................... 16
CONTENTS

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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
Schematic Diagram and 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
To Instrument's
exposed
METALLIC PARTS
Good Earth Ground
such as WATER PIPE,
CONDUIT etc.
AC Volt-meter
SAFETY PRECAUTIONS

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
SPECIFICATION
NOTE : Specications and others are subject to change without notice for improvement.
1. General Specication
*
* Provided accessory: #8/#9 , it’s different marketing request.
No Item Content Measurement ResultRemark
1 Customer BRAND Checked BRAND : LGE Product
2 User Model Name 27UL850 Checked 1pole stand
3 Sale region Worldwide Checked
4 Feature 27 ”LCD MONITOR (IPS UHD HDR) Checked
5 Chassis Name LM8BA Checked PCB, Product spec., Adjustment spec.
6 General
Scope
External SW & Adj. Joystick switch Up / Down / Left / Right / OK (Power) Checked Press and Hold : Power off
Function
Picture Mode, Ratio, S.E.S, Six Color, On Screen Con
trol,HDR10, Dual Controller, Factory Calibration
HW Calibration, Speaker 5W x2
Checked
7 Input
HDMI IN HDMI1(2.0) / HDMI2 (2.0) Checked
DP IN Display Port (1.2) Checked
USB-C IN DP(1.2),*PD 60W, USB Data Checked *PD ; Power delivery
USB DN USB 3.0 Downstream x 2 Checked Do not support Quick charging
H/P OUT Audio L/R Checked
RS-232C N/A Checked
8 Power Cord
Length 1.55±0.05m: 1.55m Refer to Suffix standard and
power cord Table. Weight 0.174kg ± 10%, 0.173kg
Color White Checked
9 Cable
Phone to RS-232
Length 0.2 ± 0.01m N/A
Do not provide
Weight 0.02kg ± 10%, N/A
Color Black N/A
USB C To C Cable
Length 1.8 ± 0.03m 1.80m
P/N : EAD63932602
(Refer to BOM)
Weight 0.0775kg ± 5% 0.077kg
Color White Checked
Impedance 1) CABLE : 90 Ω±15Ω
2) CONNECTOR : 90 Ω±10Ω
1) 84.21~94.41ohm
2) 93~95.47
DisplayPort
Length 1.50m±0.05m 1.5m
P/N : EAD63749403
(Refer to BOM)
Weight 0.136kg ± 10% 0.135kg
Color White Checked
Impedance 1) CABLE : 100Ω±5Ω
2) CONNECTOR : 100Ω±10Ω
1) 98.37~101.9ohm
2) 92.33~102.7ohm
HDMI
Length 1.50m ± 0.05m 1.5m
P/N : EAD63954402
(Refer to BOM)
Weight 0.090kg ± 10% 0.090kg
Color White Checked
Impedance 1) CABLE : 100Ω±5Ω
2) CONNECTOR : 100Ω±10Ω
1) 96.69~105.73ohm
2) 90.73~108.97ohm
10 Power (Adapter / PSU /LPB) Output: DC 19V 7.37A, 140W Adapter
Color: White, Weight : 0.58kg ±10%, without vinyl bag Checked P/N : EAY64929301(Refer to BOM)
11 Power Rating Input : DC 19V/ 7.0A Checked Request to regulation team
12 Accessory Box - - Not applied
13 Applying module list P/No Specification Checked 27” UHD MODULE (LG Display)
EAJ63750101 LM270WR3-SSA1 (Refer to BOM)

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
2. Signal Timing (Resolution)
2.1. Signal (Video & Sync)
Video
Sync
A
B
C
DEF
6.1.1 Signal (Video& Sync) – DisplayPort/USB-C
Mode section polarity
DOT
CLOCK
[MHz]
Frequency
[kHz]/[Hz]
Total
Period(E)
Display
(A)
Front
Porch(D)
Sync.
(C)
Back
Porch(B) Resolution Measurement Result Remark
1 H(Pixels) - 25.175 31.469 800 640 16 96 48 640 x 480 Checked PC : Display
Resolution
Information
V(Lines) - 59.94 525 480 10 2 33
2 H(Pixels) + 40 37.879 1056 800 40 128 88 800 x 600 Checked
V(Lines) + 60.317 628 600 1 4 23
3 H(Pixels) - 65 48.363 1344 1024 24 136 160 1024 x 768 Checked
V(Lines) - 60 806 768 3 6 29
4 H(Pixels) + 79.99 54.347 1472 1152 32 96 192 1152 x 864 Checked
V(Lines) + 60.05 905 864 1 3 37
5 H(Pixels) + 74.250 45.00 1650 1280 110 40 220 1280 x 720 Checked
V(Lines) + 60.00 750 720 5 5 20
6 H(Pixels) - 83.5 49.702 1680 1280 72 128 200 1280 x 800 Checked
V(Lines) + 59.810 831 800 3 6 22
7 H(Pixels) + 108 63.981 1688 1280 48 112 248 1280 x 1024 Checked
V(Lines) + 60.02 1066 1024 1 3 38
8 H(Pixels) + 108.00 60.00 1800 1600 24 80 96 1600 x 900 Checked
V(Lines) + 60.00 1000 900 1 3 96
9 H(Pixels) + 148.5 67.5 2200 1920 88 44 148 1920 x 1080 Checked
V(Lines) - 60 1125 1080 4 5 36
10 H(Pixels) + 277.25 133.32 2080 1920 48 32 160 1920 x 2160 Not support
V(Lines) - 60 2222 2160 54 5 3
11 H(Pixels) + 241.50 88.79 2720 2560 48 32 80 2560 x 1440 Checked
V(Lines) - 59.95 1481 1440 3 5 33
12 H(Pixels) + 266.64 66.66 4000 3840 8 144 8 3840 x 2160 Checked
V(Lines) - 30 2222 2160 54 5 3
13 H(Pixels) + 533 133.32 4000 3840 8 144 8 3840 x 2160 Checked
V(Lines) - 60 2222 2160 54 5 3
13) Recommended Timing

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
Mode section polarity DOT CLOCK[MHz] Frequency
[kHz]/[Hz]
Total
Period(E)
Display
(A)
Front
Porch(D)
Sync.
(C)
Back
Porch(B) Resolution Measurement Result Remark
1 H(Pixels) - 25.175 31.469 800 640 16 96 48 640 x 480 Checked PC : Display
Resolution
Information
V(Lines) - 59.94 525 480 10 2 33
2 H(Pixels) + 40 37.879 1056 800 40 128 88 800 x 600 Checked
V(Lines) + 60.317 628 600 1 4 23
3 H(Pixels) - 65 48.363 1344 1024 24 136 160 1024 x 768 Checked
V(Lines) - 60 806 768 3 6 29
4 H(Pixels) + 79.99 54.347 1472 1152 32 96 192 1152 x 864 Checked
V(Lines) + 60.05 905 864 1 3 37
5 H(Pixels) + 74.250 45.00 1650 1280 110 40 220 1280 x 720 Checked
V(Lines) + 60.00 750 720 5 5 20
6 H(Pixels) - 83.5 49.702 1680 1280 72 128 200 1280 x 800 Checked
V(Lines) + 59.810 831 800 3 6 22
7 H(Pixels) + 108 63.981 1688 1280 48 112 248 1280 x 1024 Checked
V(Lines) + 60.02 1066 1024 1 3 38
8 H(Pixels) + 108.00 60.00 1800 1600 24 80 96 1600 x 900 Checked
V(Lines) + 60.00 1000 900 1 3 96
9 H(Pixels) + 148.5 67.5 2200 1920 88 44 148 1920 x 1080 Checked
V(Lines) - 60 1125 1080 4 5 36
10 H(Pixels) + 277.25 133.29 2080 1920 48 32 160 1920 x 2160 Not support
V(Lines) - 60 2222 2160 54 5 3
11 H(Pixels) + 241.50 88.79 2720 2560 48 32 80 2560 x 1440 Checked
V(Lines) - 59.95 1481 1440 3 5 33
12 H(Pixels) + 297 67.5 4400 3840 176 88 296 3840 x 2160 Checked
V(Lines) - 30 2250 2160 8 10 72
13 H(Pixels) + 594 135 4400 3840 176 88 296 3840 x 2160
Checked
V(Lines) - 60 2250 2160 8 10 72
12) Recommended Timing (HDMI1.4) , HDMI ULTRA Deep Color : OFF
13) Recommended Timing (HDMI2.0) , HDMI ULTRA Deep Color : ON
6.1.2 Signal (Video & Sync) – HDMI

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
BLOCK DIAGRAM

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Copyright © LG Electronics. Inc. All rights reserved.
EXPLODED VIEW
910
900
510
500
300
310 200
400
920
540
or
520
LV1
120
330
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts
are identified by in the Schematic Diagram and 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
Only for training and service purposes

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
Assembly & Disassembly
■ Disassembly method
1-1. Tool
2. Pull the button downward and disassembly the stand
3. Remove screw 4ea
1. Put the set on a soft cloth

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
5. Disassembly the FFC, Lamp, control
D and hera
6. Remove screw 3eaandChassis assy
4 Open the Back cover with jig (first point is middle of top)

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Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
9. LCD Module
7 . Reversed Head assyand
Disassembly deco
8 . Reversed Head assyand
Remove screw 9ea

TROUBLESHOOTING GUIDE
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Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
1. NO POWER
N
Check Power connector
OK ? Replace Adapter
Y
N Y
Y
N
Replace IC601 &
Recheck
N
Y
Replace IC202 Flash Memory
Y
Check JP400,JP401
Voltage Level (19V)
Check IC601 Output
Voltage Level (+3.3V)
Check IC405,IC403, IC404Output
Voltage Level (5V,1.8V, 1.15V)
Replace IC405,IC403, IC404
&Recheck
Check X200 Clock 12MHz Replace X200

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
2. NO SCREEN ON
Replace Cable
N
Module Back Light On?
Y
N N
Replace IC402 &
Recheck
Y
N
Replace T-Con Board or Module
Y
Check IC 601
Replace Main Scaler IC
Check Panel Power
10V(JP209)
Check WLED_ENABLE High?
(IC601 Pin #27)
Check e-DP Cable for
Damage or Open
Conductors

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
3. No Video-HDMI
Check signal format and
resolution
Is it supported?
Check JK100 or JK101 for
proper connection or Damage Replace Connector
Y
N
Check HDMI 5V from Source(PC)
(JK100 and JK101)
(Pin No. 18)
Re Download EDID Data
Y
N
Y
Check HDMI Cable for
Damage or Open Connector
Y
Replace Main Scaler (IC200)

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
4. No Video-DP
Replace Main Scaler (IC200)
Check signal format and
resolution
Is it supported?
Check JK801 for proper
connection or Damage Replace Connector
Y
N
Check AUX Signal
(R137 or R142)
Y
Y
Check DP Cable for Damage
or Open Connector
Y

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
4. No USB-C
Replace Main Scaler (IC200)
Check input signal format
Is it supported?
Check JK801 for proper
connection or Damage Replace Connector
Y
N
Check AUX Signal
(R876 or R890)
Y
Y
Y
Check USB-CCable for
Damage or Open Connector
N
ReplaceIC801

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
5. No Sound(H/P)
Replace Main Scaler
(IC200)
Check the Input source.
Check the sound setting in
PC Setting like a right image.
Y
N
Check JK501 Soldering Do re-soldering
Y
N
Y
Check Cable status for
Damaged or Open
Connector
Y

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Copyright©2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
6. No Sound(Speaker)
Check the Input source.
Check Speaker Cable is
connected
Connect the Cable
correctly
Y
N
Replace Speaker and
Check the status
Replace Main Scaler
(IC200)
N
Y
Check Cable for
Damaged or Open
Connector
Y