LG 27GK750F User manual

Internal Use Only
CHASSIS : LM71F
MODEL :27GK750F
CAUTION
BEFORE SERVICING THE CHASSIS, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
SERVICE MANUAL
LED MONITOR
SERVICE MANUAL
P/NO : MFL69406833(1709-REV00)

- 2 -
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 .............................................................. 18
BLOCK DIAGRAM ................................................................................. 14
EXPLODED VIEW .................................................................................. 15
DISASSEMBLY ...................................................................................... 16
CONTENTS

- 3 -
Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by in the
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 Mȍand 5.2 Mȍ.
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

SPECIFICATION
-4 - LGE Internal Use OnlyCopyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
No Item Content Measurement Result Remark
1 Customer BRAND Checked OK
2 User Model Name 27GK750F Checked OK
3 Sale region Worldwide Checked OK
4 Feature 27” LCD MONITOR (gaming) Checked OK
5 Chassis Name LM71F Checked OK
Checked OK
External SW
& Adj.
General 5-way joystick switch
6
Scope Picture Mode, Ratio,S.E.S,Six Color,On Checked OK
Function Screen Control, Dual Controller
Gamma calibration
Length : 1.55±0.05 M / Shape : Wall-out Checked OK Power cord can be changed
7 Power Cord / Color : Black according to region.
Weight : 0.16kg±10%
Length : 1.5m ±0.05 m / Shape : Checked OK
Detachable Type / Color : Black / SET accessory
8 Cable HDMI Weight : 0.091kg±10% P/N : EAD63954401
CABLE : 100Ω± 10Ω
CONNECTOR : 100 Ω± 15Ω

-5 - LGE Internal Use OnlyCopyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
DisplayPort
Length : 1.5m±0.05m
Shape : Detachable Type / Color : Black
/ Weight : 0.095kg±10%
Checked
OK
SET accessory
P/N : EAD63749401
CABLE : 100Ω±5Ω
CONNECTOR : 100Ω±10Ω
Checked
OK
9
Power
Output: DC 19V 3.42A, 65W Adapter
Color: Black, Weight : 0.58kg ±10%,
without vinyl bag
Checked
OK
P/N : EAY62990906
10
Factory calibration report
0.002kg
Checked
OK
SET accessory / Refer to BOM
11
Applying module list
P/No
Specification
EAJ64287601
M270HTN(AUO)
Checked
OK

2. Signal Timing (Resolution)
2.1. Signal (Video & Sync)
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A
B
C
DEF
Video
Sync
.
-6 - LGE Internal Use OnlyCopyright © 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
(HDMI / DP)
1
H(Pixels)
+
48.75
31.469
800
640
16
96
48
640 x 480
V(Lines)
-
59.94
525
480
10
2
33
2
H(Pixels)
+
73.25
76.302
960
800
48
32
80
800 x 600
V(Lines)
-
120
636
600
3
4
29
3
H(Pixels)
+
115.50
97.551
1184
1024
48
32
80
1024 x 768
V(Lines)
-
120
813
768
3
4
38
4
H(Pixels)
+
91.00
63.194
1440
1280
48
32
80
1280 x1024
V(Lines)
-
59.96
1054
1024
3
7
20
5
H(Pixels)
+
187.25
130.035
1440
1280
48
32
80
1280 x1024
V(Lines)
-
119.96
1084
1024
3
7
50
6
H(Pixels)
+
297.00
135
2200
1920
88
44
148
1920 x 1080
V(Lines)
-
120
1125
1080
4
5
36
71
H(Pixels)
+
148.50
67.50
2200
1920
88
44
148
1920 x 1080
V(Lines)
+
60
1125
1080
4
5
36
8
H(Pixels)
+
346.50
166.59
2080
1920
48
32
80
1920 x 1080
V(Lines)
-
143.98
1157
1080
3
5
69

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-7 - LGE Internal Use OnlyCopyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
1）Preferred timing in Normal mode
6.1.3 HDMI Video input
Factory support
mode
Horizontal
frequency
Vertical
frequency
(Preset Mode)
(KHz)
(Hz)
1
480P
31.5
60
2
720P
45
60
3
1080P
67.5
60
9
H(Pixels)
+
577.15
282.92
2080
1920
48
32
80
1920 x 1080
V(Lines)
-
239.76
1215
1080
3
5
127
10
H(Pixels)
+
245.50
207.35
1184
1024
48
32
80
1024 x 768
V(Lines)
-
239.99
864
768
3
4
89
11
H(Pixels)
+
373.00
259.03
1440
1280
48
32
80
1280x960
V(Lines)
-
239.84
1080
960
3
4
113

How to download monitor Firmware
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ඖ
How to do ISP
Step1. Connect Realtek Jig to the monitor and PC.
Step2. Install like as attached file.
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and
PC.

How to download monitor Firmware
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Step3. Run “RTDToll”
Step4. [ISP] Icon Click

How to download monitor Firmware
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Step5. Check “Access method”.
[LG Monitor JIG: FTDIUsb]
LG Monitor JIG(P/N RAD33028001)

How to download monitor Firmware
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Step6. Option Check
Enter [ Communication Option ] menu and then uncheck the [ Check ACK]
Set User data(FE2P) area select option

How to download monitor Firmware
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Step7. Following below step
1 Check the Bank 0 checkbox
2 Click [ … ] button
3 select the SW update file( *.bin or *. hex) and then click [ open ] button.

How to download monitor Firmware
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Step8. ISP
Click Thunder icon button
Îyou see the progress bar and the status window.
after finishing SW update, you see the [success] message on status window.

BLOCK DIAGRAM
-  - LGE Internal Use OnlyCopyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes

-15 - LGE Internal Use OnlyCopyright © LG Electronics. Inc. All rights reserved.
Only for 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 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
200
400
510
330
930
500
300
900
910
920
540
A3

- 16-
Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
■Disassemble method
Fig.1 Place the monitor’s screen face down on a soft cloth.
.
Fig.2 Disassemble the Stand body with pulling down the button.
Fig 3 Remove the Screw(4EA) and disassemble the back cover
Fig 4 Disassemble the back cover (Latch Type) .

■Disassemble method
- 17 -
Copyright © LG Electronics. Inc. All rights reserved.
Only for training and service purposes
Fig 5 Remove the Cable(3EA)、Tape(2EA) and disassemble metal frame.
Fig.6 Disassemble the C/A and Joy stick assy

TROUBLESHOOTING GUIDE
-18 -
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
1. NO POWER
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-19 -
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
2. NO SCREEN ON
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-20 -
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes LGE Internal Use Only
3. No Video
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