LG UltraFine 27MD5KA User manual

P/NO :
CHASSIS :
MODEL :
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
SERVICE MANUAL
Copyright © 2016 - 2018 LG Electronics Inc. All rights reserved. Only training and service purposes.
CONFIDENTIAL
MFL69169559 (1803-REV01)
LM6FB
27MD5KA
UltraFine 5K MONITOR

- 2 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
CONTENTS .............................................................................................. 2
SAFETY PRECAUTIONS ........................................................................ 3
SPECIFICATION ....................................................................................... 4
TROUBLE SHOOTING GUIDE ................................................................ 6
BLOCK DIAGRAM ................................................................................. 14
EXPLODED VIEW .................................................................................. 15
DISASSEMBLY ...................................................................................... 16
CHECK GUIDE ........................................................................ APPENDIX
TRAINING MANUAL ................................................................ APPENDIX
CONTENTS

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

- 4 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
SPECIFICATION
NOTE : Specications and others are subject to change without notice for improvement.
1. General Specication
No Item Content Remark
1 Customer BRAND
2 User Model Name 27MD5KA
3 Sale region World Wide
4 Feature 27” LCD MONITOR(5K)
5 Chassis Name LM6FB
6 General Scope External SW &Adj. None
Function Thunderbolt3, Power Delivery,
USB Audio/Speaker/Mic/Webcam,
Ambient Light Sensor, HDCP2.2
7 Input Thunderbolt3 Thunderbolt3 input USB-C Type
USB USB3.0 / 2.0 communication In TBT3 Jack
USB down USB3.0 Downstream x 3
Audio USB data format Audio
Camera Full HD Web Camera Module LGIT
Microphone 1xDigital MEMS Mic LGIT
ALS Ambient Light Sensor LGIT
8 Power Code Length : 1.80, Shape : Wall-out, Color : Black
Weight : 0.17kg
Refer to Sufx standard
and power cord table
9 Cable TBT3
(Thunderbolt)
Length :1.8m, Shape : USB-C , Color: Black, Pin 24 Sumitomo
10 Power Input: AC100~240V 50~60Hz, 2.5A Max
Output: DC 20V 10A, 200W PSU

- 5 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
2. Signal Timing (Resolution)
2.1. Signal (Video & Sync)
3.2. H/V Timing
No. Section Pol. Dot Clock
[MHz]
Frequen-
cy
[kHz]/[Hz]
Total
Cycle
(E)
Dis-
play
(A)
Front
Porch(B)
Sync.
(D)
Back
Porch(F)
Resolution
1 H(Pixels) + 593.82 142.2 4176 4096 8 32 40 4096 x 2304
V(Lines) - 60 2370 2304 1 8 57
2 H(Pixels) + 522.61 133.32 3920 3840 8 32 40 3840 x 2160
V(Lines) - 60 2222 2160 1 8 53
3 H(Pixels) + 364.47 111.12 3280 3200 8 32 40 3200 x 1800
V(Lines) - 60 1852 1800 1 8 43
4 H(Pixels) + 234.59 88.86 2640 2560 8 32 40 2560 x 1440
V(Lines) - 60 1481 1440 1 8 32
5 H(Pixels) + 938.36 177.72 5280 5120 16 64 80 5120 x 2880 (1)
V(Lines) - 60 2962 2880 1 8 73
* (1) : Preferred timing.

- 6 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
TROUBLE SHOOTING GUIDE
1. No Video – Thunderbolt3
Check connection for
Thunderbolt3 in Source
Check input signal format
Is it supported?
Check JK101 for proper
connection or Damage Replace Connector
Y
N
Y
Check Thunderbolt3 Cable for
Damage or Open Connector
Y
Check IC200
N
Check IC500
Y

- 7 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
2. No Video – Thunderbolt3_Check IC200
Replace X200
N
Check C1102
Voltage Level (20V)
Check Power connector
OK ? Replace PSU
Y
N Y
Check IC1104 Output
Voltage Level (3.3V)
Replace IC1104 &
Recheck
Y
N
Check X200 Clock
25MHz
Replace IC203 Flash
Memory
Y
Check L305 Output
Voltage Level (0.9V)
Y
N
Replace IC200

- 8 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
3. No Video – Thunderbolt3_Check IC500
Replace X500
N
Check C1102
Voltage Level (20V)
Check Power connector
OK ? Replace PSU
Y
N Y
Check IC1101 Output
Voltage Level (3.3V)
Replace IC1101 &
Recheck
Y
N
Check X500 Clock
14.318MHz
Replace IC501 Flash
Memory
Y
Check IC1103 Output
Voltage Level (1.5V)
Replace IC1103 &
Recheck
Y
N
Check IC1102 Output
Voltage Level (1.1V)
Replace IC1102 &
Recheck
N
Y

- 9 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
4. No Screen on
Replace Cable
N
Module Back Light On?
Check IC800
Replace LED Driver IC
Y
N
N
Check Panel Power 10V (L1107)
Check IC1100 Output 10V
Replace IC1100 &
Recheck
Y
N
Check Panel eDP AUX
P501 (#9, #10 / #36, #37 )
Check IC500
Repair Main B/D
Y
N
Check MCX Cable for Damage or
Open Conductors
Check LED Driver Output
(P800 -#3, #4)
Replace T-Con Board or Module
Y
Check IC500
Replace Main SOC
N
Check WLED_ENABLE High?
Y

- 10 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
5. No Charging, No Display
Display ?
Cable Connection
To Macbook Pro
Charging ?
Swap R118
No
No
Yes
No
Swap Q102Q102 Short?
R118
Short

- 11 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
6. Charging but No Display
Display ?
Cable Connection
To Macbook Pro
Charging ?
No
Yes
No
Swap Main B'd
Display ?
Swap TBT cable
The unstable jack can make this issue.

- 12 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
7. Image Retention
Image Retention
Yes
Yes
Swap Module
Almost Image Retention (Image Sticking) is from LCD Module.
Before swapping LCD module, check the voltage (L504) is normal
or not.
Power On/Off
Image
sticking?
Check L504 voltage
Voltage
L504 is
10V?
Swap Main B'd
No

- 13 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
8. Display Blinking
Cable Connection
Record swap parts
macOs is
the latest
version
Swap direction of
TBT Cable
Display
Blinking?
Push TBT cable to Jack
strongly
No
Update macOS version
No
1st
2nd
Swap Main B'd
3rd

- 14 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
BLOCK DIAGRAM
USB-PD
USB2.0
I2C
Thunder bolt3
PCIe Gen3
Flash
8Mb
Flash
8Mb
Scaler
PWM
I2C
eDP
DDC
Flash
8Mb
PCIe to USB
TBT0
TBT1
(DP Out)
DP Out
TBT3
Micom
I2C
I2C
PWM
I2C
USB
I2C
CC1,2(Vconn),
AUX
FW Update
2xDP Input
PCIe
Down1
USB –I2S
Flash
8Mb
Audio
Amplifier
I2S
Container
ID
USB-C
Hub
Down1
Down2
Down3
Down4
Upstream
Flash
8Mb
VBUS
VBUS
VBUS
USB-C USB-C
USB-C
Down2
USB
I2C
I2C
I2S0
I2S1
MIC EQ
Fan
80x80,1500
Thermal
Sensor
MM3286
ALS
BLU LGD
4CH / 145mA
500nit(typ)
TCON LGD
27" eDP
5120x2880
BLU Driver
I2S
Speaker
I2C
I2C
ISP
MIPI-to-
USB
CIL
PWM
Hsync
FW Update
SPI
SPI
I2C
eDP
eDP eDP
HBR2 4lane x 2
GPIO
BLC EN
LED
Driver
Camera
20V
TDM
Converter
USB3.0
Hub
I2C
I2C
Container ID & EDID Match ing
USB2.0
USB3.0
USB2.0
USB3.0

Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
- -
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
900
300
200
140
830
580
530
545
540
130
120
700
AM1
400
220

- 16 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
DISASSEMBLY
1) Open the set from the Box and Put on set on at place.
2) Detach the stand moving button.
3) Unscrew the 4EA screw from Back cover.
4) Disassemble the bottom of Cabinet by hand
*Caution : Handle with care from scratch
5) Disassemble the bottom of Back cover by hand.
*Caution : Handle with care from scratch and latch broken Pull
back cover softly to disassemble the latch
i) Bottom disassemble → ii) Left/Right side disas-
semble → iii) Top disassemble
6) Disassemble LED Harness, eDP cable, Camera Harness
and Tape.
7) Unscrew the 7EA screw to detach Rear shield from LCM.
②Camera
③eDP
①LED
④Tape
SCRE
W

- 17 - Copyright © - LG Electronics Inc. All rights reserved.
Only training and service purposes.
8) Lift up the board from NUT of Rear shield
* Caution : Handle with care to prevent USB Jack bending
i) Push board right bottom area to lift the board from
NUT.
ii) Push board top bottom area to lift the board from
NUT.
iii) Push USB jack to lift the board from NUT.
9) Disassemble Vertically Board from Rear shield to prevent
USB jack bending and Check the USB jack Deformation
and bending or not
* Reference : LCM, Chassis Frame status
Board
NUT
NUT
NUT
USB
Jack
LCM
Power PCBA M ain PCBA

CHECK GUIDE
Copyright ⓒ2016 - 2018 LG Electronics Inc. All rights reserved.
Only training and service purposes.

1. Execute “DDCCI_TestApp.exe”
0.Connect PC and Monitor
Thunderbolt3 Cable
P/N : EAD63988301
Copyright ⓒ2016 - 2018 LG Electronics Inc. All rights reserved.
Only training and service purposes.

①②③④⑤⑥⑦⑧⑨⑩⑪⑫⑬⑭⑮
①Select ‘Secondary Display’ ②Check ‘DDCCI’
③Click Initialize
2. Connection to monitor
④Click Get Aging
Copyright ⓒ2016 - 2018 LG Electronics Inc. All rights reserved.
Only training and service purposes.