LG 27UD68P Schematic

Internal Use Only

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COLOR MONITOR

SERVICE MANUAL

CHASSIS NO. : LM55H

MODEL:

CAUTION

BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

P/NO : MFL68962211(1601-REV00) Printed in China

27UD68P

CONTENTS

CONTENTS .............................................................................................. 2

PRECAUTION............................................................................................3

SERVICING PRECAUTIONS.....................................................................4

SPECIFICATIONS......................................................................................6

TIMING CHART .......................................................................................11

ADJUSTMENT .........................................................................................14

BLOCK DIAGRAM...................................................................................18

TROUBLE SHOOTING ............................................................................19

EXPLODED VIEW .................................................................................. 22

SVC. SHEET ...............................................................................................

- 2 -

LGE Internal Use Only

PRECAUTION

WARNING FOR THE SAFETY-RELATED COMPONENT.

• There are some special components used in LCD monitor that

are important for safety. These parts are marked on the schematic diagram and the Exploded View. It is essential that these critical parts should be replaced with the manufacturer’s specified parts to prevent electric shock, fire or other hazard.

• Do not modify original design without obtaining written permission from manufacturer or you will void the original parts and labor guarantee.

TAKE CARE DURING HANDLING THE LCD MODULE WITH BACKLIGHT UNIT.

• Must mount the module using mounting holes arranged in four corners.

• Do not press on the panel, edge of the frame strongly or electric shock as this will result in damage to the screen.

• Do not scratch or press on the panel with any sharp objects, such as pencil or pen as this may result in damage to the panel.

• Protect the module from the ESD as it may damage the electronic circuit (C-MOS).

WARNING

BE CAREFUL ELECTRIC SHOCK !

• If you want to replace with the new backlight (CCFL) or LIPS part, must disconnect the AC power because high voltage appears at inverter circuit about 650Vrms.

• Handle with care wires or connectors of the inverter circuit. If the wires are pressed cause short and may burn or take fire.

Leakage Current Hot Check Circuit

AC Volt-meter

Good Earth Ground such as WATER PIPE,

To Instrument's exposed METALLIC PARTS

When 25A is impressed between Earth and 2nd Ground for 1 second, Resistance must be less than 0.1

*Base on Adjustment standard

0.15uF

1.5 Kohm/10W

CONDUIT etc.

Ω

• Make certain that treatment person’s body are grounded through wrist band.

• Do not leave the module in high temperature and in areas of high humidity for a long time.

• The module not be exposed to the direct sunlight.

• Avoid contact with water as it may a short circuit within the module.

• If the surface of panel become dirty, please wipe it off with a softmaterial. (Cleaning with a dirty or rough cloth may damage the panel.)

CAUTION

Please use only a plastic screwdriver to protect yourself from shock hazard during service operation.

- 3 -

LGE Internal Use Only

SERVICING PRECAUTIONS

CAUTION: Before servicing receivers covered by this service

manual and its supplements and addenda, read and follow the

SAFETY PRECAUTIONS on page 3 of this publication.

NOTE: If unforeseen circumstances create conflict between the

following servicing precautions and any of the safety precautions on page 3 of this publication, always follow the safety precautions. Remember: Safety First.

General Servicing Precautions

1. Always unplug the receiver AC power cord from the AC power source before; a. Removing or reinstalling any component, circuit board

module or any other receiver assembly.

b. Disconnecting or re-connecting any receiver electrical plug or

other electrical connection.

c. Connecting a test substitute in parallel with an electrolytic

capacitor in the receiver. CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard.

2. Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".

3. Do not spray chemicals on or near this receiver or any of its assemblies.

4. Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the contacts with a pipe cleaner, cotton-tipped stick or comparable non-abrasive applicator; 10% (by volume) Acetone and 90% (by volume) is opropyl alcohol (90%-99% strength) CAUTION: This is a flammable mixture. Unless specified otherwise in this service manual, lubrication of contacts in not required.

5. Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.

6. Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.

7. Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead. Always remove the test receiver ground lead last.

8. Use with this receiver only the test fixtures specified in this

service manual.

CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage caused by static by static electricity.

1. Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed to prevent potential shock reasons prior to applying power to the unit under test.

2. After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4. Use only an anti-static type solder removal device. Some solder removal devices not classified as "anti-static" can generate electrical charges sufficient to damage ES devices.

5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.

6. Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive material).

7. Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES device.)

General Soldering Guidelines

1. Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within the range or 500ºF to 600ºF.

2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.

3. Keep the soldering iron tip clean and well tinned.

4. Thoroughly clean the surfaces to be soldered. Use a mall wirebristle (0.5 inch, or 1.25cm) brush with a metal handle. Do not use freon-propelled spray-on cleaners.

5. Use the following unsoldering technique a. Allow the soldering iron tip to reach normal temperature.

(500ºF to 600ºF) b. Heat the component lead until the solder melts. c. Quickly draw the melted solder with an anti-static, suction-

type solder removal device or with solder braid.

CAUTION: Work quickly to avoid overheating the circuit

board printed foil.

6. Use the following soldering technique. a. Allow the soldering iron tip to reach a normal temperature

(500ºF to 600ºF)

b. First, hold the soldering iron tip and solder the strand against

the component lead until the solder melts.

c. Quickly move the soldering iron tip to the junction of the

component lead and the printed circuit foil, and hold it there only until the solder flows onto and around both the component lead and the foil. CAUTION: Work quickly to avoid overheating the circuit board printed foil.

d. Closely inspect the solder area and remove any excess or

splashed solder with a small wire-bristle brush.

- 4 -

LGE Internal Use Only

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

Removal

1. Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts.

2. Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the IC.

Replacement

1. Carefully insert the replacement IC in the circuit board.

2. Carefully bend each IC lead against the circuit foil pad and solder it.

3. Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete TransistorRemoval/Replacement

1. Remove the defective transistor by clipping its leads as close as possible to the component body.

2. Bend into a "U" shape the end of each of three leads remaining on the circuit board.

3. Bend into a "U" shape the replacement transistor leads.

4. Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection.

Power Output, Transistor Device Removal/Replacement

1. Heat and remove all solder from around the transistor leads.

2. Remove the heat sink mounting screw (if so equipped).

3. Carefully remove the transistor from the heat sink of the circuit board.

4. Insert new transistor in the circuit board.

5. Solder each transistor lead, and clip off excess lead.

6. Replace heat sink.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board. (Use this technique only on IC connections).

1. Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).

2. carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.

3. Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.

4. Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

At Other Connections

Use the following technique to repair the defective copper pattern at connections other than IC Pins. This technique involves the installation of a jumper wire on the component side of the circuit board.

1. Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous condition will not exist if the jumper wire opens.

2. Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly connected to the affected copper pattern.

3. Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead of the nearest component on the other side. Carefully crimp and solder the connections. CAUTION: Be sure the insulated jumper wire is dressed so the it does not touch components or sharp edges.

Diode Removal/Replacement

1. Remove defective diode by clipping its leads as close as possible to diode body.

2. Bend the two remaining leads perpendicular y to the circuit board.

3. Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.

4. Securely crimp each connection and solder it.

5. Inspect (on the circuit board copper side) the solder joints of the two "original" leads. If they are not shiny, reheat them and if necessary, apply additional solder.

Fuse and Conventional Resistor Removal/Replacement

1. Clip each fuse or resistor lead at top of the circuit board hollow stake.

2. Securely crimp the leads of replacement component around notch at stake top.

3. Solder the connections. CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to prevent excessive component temperatures.

- 5 -

LGE Internal Use Only

SPECIFICATIONS

1. General Specification

1 Customer BRAND

2 User Model Name 27UD68P

3 Sale region Worldwide

4 Feature 27” LCD MONITOR(UHD)

5 Chassis Name LM55H

External SW

General

6

Scope

7 Power Cord

9 Power

& Adj.

Function

HDMI

DisplayPort

5-way joystick switch

PBP, Picture Mode, Ratio, S.E.S, Six Color, On Screen

Control, Dual Controller

Gamma calibration

Length : 1.00±0.05 M / Shape : Wall-out / Color : Black

Weight : 0.16kg

Length : 1.5m / Shape : Detachable Type / Color : Black

Weight : 0.091kg

CABLE : 100Ω±10Ω

CONNECTOR : 100Ω±15Ω

Length : 1.8m / Shape : Detachable Type / Color : Black

Weight : 0.095kg

CABLE : 100Ω±5Ω

CONNECTOR : 100Ω±10Ω

Input: AC100~240V 50~60Hz,1.1A Max

Output: DC 19V 2.1A

40W Adapter

Weight : 203g (EAY63190003)

Power cord can be changed

according to region.

If wall-mount adapter is

applied, Power cord doesn’t

apply to the BOM

SET accessory /

P/N : EAD00926125

SET accessory /

P/N : EAD63127603

14 Applying module list

P/No Specification

EAJ63750201 LM270WR3-SSA1

- 6 -

Support FreeSync funct

New Blade 27” Module

LGE Internal Use Only

ion

2. Mechanical specification

No Item Content Remark

Width (W) Length (D) Height (H)

1

2

3

4

Product

Dimension

Product

Weight

Container

Loading

Quantity

Stand

Assy

Before Packing

After Packing

Only SET

With BOX 10.8kg

Only Stand / Accessory 0.5±5%/0.4±5%

Individual or

Palletizing

Type

Size (W x D x H)

Tilt Degree

Tilt force

Folding Degree

Height length

829.9 252.4 428.9

829.9 49.2 379.8

98.3 21.2

8.0kg/5.9kg With Stand / Without Stand

20ft 40ft

Indi. Pallet Indi. Pallet

200 200 600 440

Base detachable

504.3*252.4*418.8

-5(+1/-5) ~ 20(+1/-5) degree

1.0~3.0

N/A

120±2

Middle Cabinet : Black Glossy

52.9

mm, With Stand

mm, Without Stand

mm

EA

mm

kgf

mm

5 Appearance General

Back cover : Black Glossy

Stand Body : Black hairline and Glossy Stand

Base : Black hairline and Glossy

- 7 -

LGE Internal Use Only

3. Optical Character

1

2

3

Viewing Angle <CR≥10>

Luminance(휘도)

Contrast Ratio(명암 비)

Horizontal(R/L) : +89º/-89º ( (Typ.) Vertical(Top/Bottom) : +89º/-89º (Typ.)

Average Luminance

2

(cd/m

) Average Luminance

2

(cd/m

) Average Luminance

2

(cd/m

) Luminance Uniformity

250(min), 300 (Typ.) (Full white pattern, 0.7V)

220 (min) (Full white pattern, 0.7V)

190 (min) (Full white pattern, 0.7V)

75%(min),

700(MIN), 1000(TYP), DFC Æ 1,000,000:1(min), 5,000,000:1(Typ.)

Warm (6500K)

Medium (8000K)

Cool (9300K)

DFC test condition : Full black pattern (MSPG 126 timing) DFC : ON (Picture>Picture Adjust)

4 Response Time TGTG(Gray to Gray): 14ms(Typ.), 25ms(Max)

Minimum Normal Maximum

CIE Color

5

6 Color Coordinate

7 Color weakness Red signal

8

Coordinates

(색 좌표)

RGB COLOR coordi

nates

White

White signal

reader mode

RED

GREEN

W

X

WY 0.329 WX

WY 0.305 WX WY 0.298

W

X

WY 0.360 W

X

WY 0.250

Rx

Ry 0.334 Gx 0.307 Gy 0.637

Bx 0.150

Typ-0.03

Typ-0.02

Typ-0.03

0.313

0.295

0.283

0.365

0.490

0.652

Typ+0.03

Typ+0.02

Typ+0.03 Full red pattern

Typ+0.03

Warm

(6500K) Medium

(8000K)

Cool

(9300K)

Full white

pattern -

Warm(6500K)

BLUE

By 0.060

- 8 -

LGE Internal Use Only

4. Engineering Specification

2 Operating Frequency

3 Resolution

Single

PBP

Single

PBP

HDMI

DP

HDMI

DP

HDMI

DP

HDMI

DP

Horizontal 30 ∼ 135kHz

Vertical 56 ∼ 61 Hz HDMI2.0 Native : 60Hz

Horizontal 30 ∼ 135kHz

Vertical 56 ∼ 61 Hz

Horizontal 30 ∼ 135kHz

Vertical 56 ∼ 61 Hz Native : 60Hz

Horizontal 30 ∼ 135kHz

Vertical 56 ∼ 61 Hz

Max. 3840×2160 @ 60Hz

Recommend 3840×2160 @ 60Hz

Max. 3840×2160 @ 60Hz

Recommend 3840×2160 @ 60Hz

Max. 1920×2160 @ 60Hz

Recommend 1920×2160 @ 60Hz

Max. 1920×2160 @ 60Hz

Recommend 1920×2160 @ 60Hz

Native : 60Hz, FreeSync Range :

40-60Hz

Native : 60Hz, PBP mode can’t

support FreeSync

4 Input Voltage Voltage :100 – 240 Vac, 50 or 60Hz

DisplayPort 10-bit color

5 Color depth

HDMI1 / HDMI2 Deep Color(10bit, 12bit)

HDMI 100 ohm(-+10%)

6 Impedance Pattern

DP 100 ohm(-+10%)

- 9 -

LGE Internal Use Only

7 Inrush Current Cold Start : 50 A Hot : 120 A

8

Operating Condition

On Mode On/On Active

Sleep Mode

Off Mode Off 0.3W DC Switch Off

Sync

(H/V)

Off/On

On/Off

Off/Off

Video LED Wattage

41W(Typ)

48W(Max)

White

29W

Max 19V,

White

1.9A

48W - Adapter input

Off

White

Blinking

0.5W

- Adapter input /

UHD@60Hz, Full white,

Outgoing Condition

- Manual/spec-sheet spec :

EPA6.0

condition+250nit+110%(mar

gin)

- Refer to measurement

condition(1) – page 21 /

Adapter output

PC : Stand-by Mode.

9

10

EPA On/On Test video White 66.31W EPA6.0 test standard

ERP A class / Condition :

ERP On/On Test video White 30.2W

Outgoing condition

Power rating - - - 19V 2.0A

Efficiency

low : 15

Tes t wi th o u t go i n g

condition(출하조건)

SMART ENERGY

On/Off -

-

+/- 5%

-. Backlight 100 / Test video

SAVING

high : 25

+/- 5%

-. Refer to measurement

condition(2) – page 17

MTBF 30,000 HRS with 90% confidence level Lamp Life : 30,000

Hours(Min)

Using Altitude 5,000 m (for Reliability) 3,000m(for FOS)

- 10 -

LGE Internal Use Only

11

Environ

ment

Conditi

on

operating Temperature 0°C ~ 40°C

Humidity Less than 80%

Storage Temperature -20 C ~ 60 C

Humidity Less than 85%

OSD

Menu

Quick

Settings

PBP

Brightness 1 – 100

Contrast 1 – 100

Volume 1 – 100, Mute

Input

HDMI1 / HDMI2 / DP

Ratio Wide / Original / 1:1

SUB Off / HDMI1 / HDMI2 / DP

Sound out

Main Audio / Sub Audio

Swap

Sub Full

Main Wide / Original

Ratio

Sub Wide / Original

Custom / Reader / Photo / Cinema

Picture Mode

Color weakness / FPS Game1/FPS

Game 2 / RTS Game/Custom(Game)

/ sRGB /

Picture

Super

Resolution

High/ Middle/ Low / Off /

+

Sharpness

0 – 100

Black Level High / Low

Picture

Adjust

HDMI HD

UHD Deep

On / Off

Color

DFC On / Off

Game FreeSync On / Off

When UHD Deep

Color on,

screen noise/flicker

could be occurred

with some HDMI

device.

- 11 -

LGE Internal Use Only

Adjust Black

0-100

Stabilizer

Response

High / Middle / Low / Off

Time

Gamma 0 / Gamma 1 / Gamma 2 /

Gamma

OFF

Manual 5000 - 10000

Color Temp

Custom -

Red 0 -100

Green 0 - 100

Blue 0 -100

Red Hue / Saturation : 0 – 100

Green Hue / Saturation : 0 – 100

Blue Hue / Saturation : 0 – 100

Color

Six Color

Cyan Hue / Saturation : 0 – 100

Adjust

Magenta Hue / Saturation : 0 – 100

General

Yellow Hue / Saturation : 0 – 100

Reset Reset / Cancel

English, Germanic, French, Spanish,

Italian, Swedish, Finnish, Portuguese,

Language

Portuguese(brazil), Polish, Russian,

Greek, Ukrainian, Chinese,

Japanese, Korean

Smart Energy Saving Off / Low /High

FreeSync On / Off

Power LED On / Off

Automatic Standby Off / 4H / 6H / 8H

DP 1.2 Enable / Disable

Buzzer On/Off

OSD Lock On / Off

- 12 -

LGE Internal Use Only

LG 27UD68P Schematic

Specifications and Main Features

Frequently Asked Questions

User Manual