LG LED LCD Monitor Service Manual

Contents

• Safety Precautions
• Specifications
• Adjustment Instruction
• Block Diagram
• Exploded View
• Disassembly
• Trouble Shooting Guide

Safety Precautions

Important Safety Notice

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by a warning symbol (△!) in the Exploded View. It is essential that these special safety parts are 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 the 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 to protect the technician from electrical shocks.
• This also protects the receiver and its components from damage due to accidental shorts introduced during service.
• If any fuse (or Fusible Resistor) is blown, replace it with the specified type.
• When replacing high wattage resistors (Oxide Metal Film Resistor, over 1 W), keep the resistor 10 mm away from the 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 exposed metallic parts (e.g., antennas, terminals) to ensure safe operation.

Leakage Current Hot Check

Plug the AC cord directly into the AC outlet. Do not use a line isolation transformer during this check.

Connect a 1.5 KΩ / 10 watt resistor in parallel with a 0.15 µF capacitor between a known good earth ground (e.g., water pipe, conduit) and the exposed metallic parts.

Measure the AC voltage across the resistor using an 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 (approximately 0.5 mA). If measurements exceed these limits, the set must be checked and repaired before return to the customer.

Leakage Current Hot Check Circuit Description: An AC Voltmeter is connected in series with a 1.5 kΩ / 10W resistor and a 0.15µF capacitor, which is then connected between the exposed metallic parts of the device and a good earth ground.

Leakage Current Cold Check (Antenna Cold Check)

With the instrument AC plug removed from the AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the 'on' position.

Connect one lead of an ohmmeter to the AC plug prongs tied together and touch the other ohmmeter lead to each exposed metallic part (e.g., antenna terminals, phone jacks).

If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1 MΩ and 5.2 MΩ. If there is no return path, the reading must be infinite.

Note: When 25A is impressed between Earth and 2nd Ground for 1 second, resistance must be less than 0.1 Ω (based on adjustment standard).

Specifications

1. General Specification

Provided accessory: #7/#8

6. Signal Timing (Resolution)

<Analog>

1) Main Recommended Timing

6.1.2 HDMI Video input

10. LCD Panel Characteristic

-. 22MK600*** (M215HCA-P02)

-. 24MK600 (M238HCA-P3B)

-. 24MK600(LGD LM238WF2-SSK1)

-. 27MK600 (LGD LM270WF7-SSA1)

Standard Measurement Condition

• Ambient Luminance Level: dark (< 10 lux)
• Ambient Temperature: Normal Temperature (10 ~ 25 °C)
• Warm-up Time: More than 30min (at Full White Pattern)
• Input Signal: 1920x1080@240Hz
• Contrast: 70 / Brightness: Max. 100
• 6500K: Color Temperature Setting is 6500 K (if not special specification)
• Another Spec.: Product Specification Standard (LG(55)G1-1034)
• Cosmetic Spec.: LCD Module IIS Spec.

Adjustment Instruction

1. Application

This document applies to LM8EA chassis 22/24/27MK600M LCD Monitors manufactured in the Monitor Factory or produced based on this data.

Manufacturing Type: SET

2. Designation

Adjustments are performed in the designated order and must be followed according to the plan, which can be changed only upon agreement.

• Power Adjustment: Free Voltage
• Magnetic Field Condition: Nil.
• Input signal Unit: Product Specification Standard
• Reserve after operation: Above 5 Minutes (Heat Run)
• Conditions: Temperature: 25°C±5°C / Relative humidity: 65 ±10% / Input voltage: 100 ~ 240V, 50/60Hz
• Adjustment equipments: Color Analyzer (CA-210 or CA-110, UA-10), DDC Adjustment Jig equipment.

3. Main PCB Check Process

APC - After Manual-Insult, executing APC

3.1 ADC Process

XxMK600M models use internal ADC; no D-SUB cable connection is needed.

Internal ADC Steps:

• On AC power, with Aging mode enabled, check ADC values to decide if calibration is needed.
• Read ADC OFFSET and GAIN flags from NVRAM addresses 0xA8, 0x0D, 0x0E.
• If these values are not 0xAA in Aging mode, internal ADC calibration must be performed.
• If internal ADC calibration is successful, save the ADC result, set OFFSET and GAIN flags to 0xAA, and set the Internal_ADC flag to INTERNAL.
• Display the ADC result on the Aging Mode OSD and Service OSD.

If internal ADC is not used, follow these steps:

• Input a 16-step pattern for ADC (Mode12, pattern 11) with a video level of 700 mVp-p.
• Adjust using the AUTO_COLOR_ADJUST command.
• Confirm a "Success" message on screen or check if the data at EEPROM addresses 0xFD, 0xFE (0xA6) is 0xAA after waiting 5 seconds.
• If a "FAULT" message appears or the data at 0xFD, 0xFE (0xA6) is not 0xAA, repeat the adjustment.
• Upon completion of all adjustments, the values for 6500K, User Color, and 9300K are saved automatically.

3.2 Main PCB Function Test

Check display/audio according to interface.

3.2.5.9 V-Com Adjustment

For INX panel: Adjusting V-COM via software is required. This involves adjusting the V-Com level to minimize flicker.

Process: Use LG commands to check Flicker Level. If the Flicker Level does not meet the specification, adjust the V-com value via the panel's IIC line. If the flicker level meets the specification, save the V-com value in EEPROM.

Connection Diagram Description: The setup involves a monitor connected to a PC via RS-232C, with a probe (CA-P12/15 or CA-P15) connected to the monitor's RGB + IIC interface, passing through a buffer and then to the IIC interface of the scaler.

V-com adjustment Spec: For 22MK600M/24MK600M***GESN models, Flicker level must be ≤ 25.

3.3 Confirm PRESET 6500K Color Coordinates and Adjust PRESET 9300K Color Coordinates

• Set the monitor to Aging mode ON using the AGING_ON/OFF command.
• Select the module being used in production via the MODULE SELECT command.
• Send the SYSTEM RESET command to set the module data.
• Input a Full White Pattern (Video level: 700 mVp-p).
• 9300K Color Adjustment:
  • This model is a Non-TCO Appliance. If TCO 03 specifications need to be met later, refer to the following methods:
  • Adjust to meet x = 0.287±0.005, y=0.303±0.005 within 5 minutes.
  • Adjust to meet x= 0.285±0.005, y= 0.301±0.005 within 5~30 minutes.
  • Adjust to meet x=0.283±0.005, y=0.298±0.005 after 30 minutes, and confirm.
  • Adjust to meet Y = over 140cd and confirm.
• Input a Full White Pattern (Video level: 700 mVp-p).
• Set the color mode to 6500K using the COLOR_MODE_CHANGE command.
• 6500K Color Adjustment:
  • If TCO 03 specifications need to be met later, refer to the following methods:
  • Adjust to meet x = 0.317 ± 0.005, y=0.332±0.005 within 5 minutes.
  • Adjust to meet x= 0.315 ± 0.005, y= 0.331±0.005 within 5~30 minutes.
  • Adjust to meet x=0.313 ± 0.005, y=0.329±0.005 after 30 minutes, and confirm.
  • (Option) For 6500K color adjustment at Gumi & NT: First, check AUV. If it's under 0.0065, no adjustment is needed. Otherwise, adjust to meet u'= 0.198±0.0065, v'=0.469±0.0065. Adjust to meet Y = over 180 cd and confirm.
• Input Full White Pattern (Video level: 700 mVp-p).
• Set to 6500K using the COLOR_MODE_CHANGE command.
• 6500K Color Adjustment:
• Input Gamma calibration Pattern (R,G,B, Grey 20).
• This model requires Gamma 2.2 calibration.
• Gamma Calibration and Verification Process:
• Start
• Read Elapsed time
• Measure
• Verify
• Output Report
• End
• If TCO 0.3 spec needs to be satisfied later, refer to the method below.
• (Option) For 6500K color adjustment at Gumi & NT: First, check UV. If it's under 0.0065, the set is not adjusted. Otherwise, adjust to meet u'= 0.198±0.0065, v'=0.469±0.0065. Adjust to meet Y = over 200 cd and confirm.
• If TCO 0.6 spec needs to be satisfied later, refer to the method below.
• Adjust to meet Y = over 200 cd and confirm.

3.2.4.5. Confirm User Color Coordinates

• Confirm if User color is saved the same as 6500K.
• After confirming Color coordinates, return to 6500K.
• Confirm if the user color value is 50. If the user color (R/G/B) value is 30, adjust again.

4. Total Assembly Line Process

4.1 Write HDCP 1.4

HDCP 1.4 KEY is included in the Scaler. No need to write HDCP 1.4 key.

4.2 White Balance Check and Factory Calibration

Before factory calibration, check the White Balance according to the specification below:

• HDMI 1920x1080, Full White
• Tolerance: -/+0.015
• Luminance Spec (min): 200 cd/m² (for 22/24"/27" models)
• Check condition: Custom mode (out-going condition)

a. Factory Calibration (2.2): dE, Color Temperature (6500k). Reference Model: 24MP68VQ.

Note: Manual W/B Process

1. When in DC OFF Condition.
2. Press power button 3 times to the left.
3. Press power button once to the right.
4. DC on.
5. Press power button up to show Navigation OSD.
6. Press power button left to show Service Menu (Select "Menu" in Navigation OSD).

Circumstances for Adjustment: Please make circumstances as below when performing adjustment.

4.3 DPM Operation Check

• Measurement Condition: 100~240V@ 50/60Hz
• Set Input to D-Sub, HDMI.
• Turn off the source device.
• Check DPM operation as per the table below:

5. Shipping Condition

Make sure to perform FACTORY RESET at the final process.

6. Signal Composition for Adjustment

6.1 I2C (100K BPS)

6.2 COMMUNICATION START

Command: START 6E A STOP 50Ms

#Until ACK BIT goes LOW, Repeat it.

6.3 Command Form

Command form uses DDC2AB standard communication protocol.

Command Structure: START 6E A 50 A LEN A 03 A CMD A 00 A VAL A CS A STOP

• LEN: DATA BYTE number to send.
• CMD: Command language that monitor executes.
• VAL: FOS DATA.
• CS: Dada's CHECHSUM that transmit.
• DELAY: 50MS.
• A: Acknowledge.

6.4 Screen Adjust Command (LENGTH = 84)

- Apply standard: EU region HDMI model

- EU region Suffix: EU / EK / PD / EW/MA

6.5. EEPROM Data Write

6.5.1 Signal TABLE

START 6E A 50 A 84+n A 03 A CMD A ADH A ADL A CS A STOP

LEN : 84h+Bytes

CMD: E8h

ADH: E²PROM Slave Address (A0,A2,A4,A6,A8,AA,AC,AE), Not 00h (Reserved by Buffer To EEPROM)

ADL: E²PROM Sub Address (00~FF)

Data: Write data

Delay: 20ms

6.5.2. Command Set

* Use

FOS Default write: <14mode data> write

SyncFlags, HPeriodH, HPeriodL, VtotalH, VtotalL, SrcHTotalH, SrcHTotalL, SrcHStartH, SrcHStartL, SrcVStartH, SrcVStartL, HsyncPhase

Temporary Data write: Write to particular address of EEPROM.

6.6 E²PROM Data Read

6.6.1 Signal TABLE

START 6E A 50 A 84 A 03 A CMD A ADH A ADL A CS A STOP

Delay 150ms

START 6F A D1 A ... Dn A STOP (128 Bytes)

6.6.2 COMMAND SET

6.6.3 Use

Read E²PROM's specific area as unit of 128(80h)-byte. (84h)

6.6.4 EDID Write

EEPROM access by using DDC2B protocol.

• 1-Byte write: START A0 A L A D A STOP (L: 0x00~0x7F, D: data)
• 8-byte write: START A0 A L A Data A ... A Data8 A STOP (L: 0x00,0x10,....0x70)

6.6.5 EDID Read

DDC2B Command.(A0/A1)

START A0 A 00 START A1 A Data1 ... Data128 A CS A STOP (128 Byte transfer of EDID Buffer of MICOM)

Block Diagram

Description: The block diagram illustrates the main components and signal flow of the monitor. Key components include:

• Power Supply: MP3378E LED Driver (5V for LED Backlight), MP2122A DC/DC (3.3V, 1.1V).
• Main Processing: SCALER RTD2522R, which handles LVDS input from the Panel and interfaces with FLASH 8M, Key 1 & Key 2, Control Key, RGB, HDMI #1, HDMI #2, and Headphone OUT.
• Display Panel: 1920x1080 resolution panel.
• Interfaces: RGB, HDMI #1, HDMI #2, Headphone OUT.
• Control: Key 1 & Key 2, Control Key.

Exploded View

Description: The exploded view shows the physical assembly of the monitor. Components are identified by numbers (e.g., 200, 300, 330, 400, 500, 510, 520, 540, 900, 910, 920, 930). It is essential to use the same replacement components as recommended in this manual to prevent hazards.

Important Safety Notice: Many electrical and mechanical parts have special safety-related characteristics, identified by a warning symbol (△!) in the Exploded View. Replacing these parts with incorrect components can lead to Shock, Fire, or other Hazards. Do not modify the original design without manufacturer permission.

Disassembly Method

1. Place the product on a protective pad.
2. Use a screwdriver to remove the stand-base screw (1 piece) or use your hands to remove the thumb-screw (1 piece).
3. Disassemble the stand-base.
4. Disassemble the screw cover.
5. Disassemble the stand-body screws (2 pieces).
6. Disassemble the stand-body.
7. Disassemble the jack-screw (1 piece).
8. Use a jig to disassemble the back cover.
9. Disassemble the cables.
10. Disassemble all UDM screws.
11. Disassemble the middle-cabinet.
12. Disassemble the DMS screws (2 pieces).
13. Disassemble the DMS.
14. Disassemble the PCB screws (2 pieces).
15. Disassemble the PCB.
16. Disassemble the Control-PCB and Cable.

Trouble Shooting Guide

First, check for any SVC Bulletins in the GCSC System for these models.

No Power

• Check JP100 Voltage Level (19V).
• If OK (Y), check the Power connector. If OK, replace the Power Board.
• If not OK (N), check IC101 Output Voltage Level (5VS).
• If OK (Y), check IC100 Output Voltage Level (1.1V, 3.3V).
• If OK (Y), check X201 Clock (14.318MHz).
• If OK (Y), replace IC201 Flash Memory.
• If any check fails (N), replace the corresponding component (IC101, IC100, X201) and recheck.

No Screen on

• Check if Module Back Light is On.
• If Yes (Y), check Panel Power 5V (JP229) and IC101 Output 5V.
• If OK (Y), check Panel Clock P101(#10,11,22,23).
• If OK (Y), check FFC Cable for Damage or Open Conductors.
• If OK (Y), replace the T-Con Board or Module.
• If any check fails (N), replace IC101 & Recheck.
• If Panel Clock check fails (N), check IC203 Repair Main B/D.
• If FFC Cable check fails (N), replace the Cable.
• If Back Light check fails (N), check LED Driver FB (P700 1,6). If OK, replace IC101 & Recheck. If not OK, check IC203 Replace Main Scaler IC.

No Video - D-sub

• Check if the input signal format is supported.
• If Yes (Y), check the D-sub Cable for Damage or Open Connector.
• If Yes (Y), check D-sub (P201) pin for proper connection or Damage.
• If Yes (Y), check I2C Signal (M200, M201).
• If Yes (Y), replace the Main Scaler (IC201).
• If any check fails (N), replace the Connector or Re-download EDID Data as appropriate.

No Video - HDMI

• Check if the input signal format is supported.
• If Yes (Y), check the HDMI Cable for Damage or Open Connector.
• If Yes (Y), check HDMI pin (JP102,103,104,105,106) for proper connection or Damage.
• If Yes (Y), check I2C Signal (JP105,106).
• If Yes (Y), replace the Main Scaler (IC201).
• If any check fails (N), replace the Connector or Re-download EDID Data as appropriate.