LG Flatron W1941S Service Manual

The LG Flatron W1941S is a 19-inch LCD monitor featuring 1440x900 resolution, 5ms response time, 300 cd/m² brightness, 700:1 contrast ratio, D-Sub and DVI-D inputs, built-in speakers, and VESA wall mount compatibility. This service manual covers technical specifications, disassembly procedures, troubleshooting, circuit diagrams, and maintenance guidelines for qualified service technicians.

1. Product Overview 2. Technical Specifications 3. Disassembly Instructions 4. Circuit Diagrams 5. Power Supply Unit 6. Main Board 7. LCD Panel 8. Troubleshooting Guide 9. Parts List 10. Safety Precautions 11. Service Information

Product Overview

The LG Flatron W1941S monitor consists of main components: LCD panel assembly, main board, power supply board, control buttons, stand assembly, and back cover.

Component	Description
LCD Panel	19-inch TFT LCD, 1440x900 resolution
Main Board	Signal processing and control circuitry
Power Supply	AC/DC conversion and power distribution
Control Buttons	Power, Menu, Auto, Volume controls
Input Ports	D-Sub (VGA) and DVI-D connectors
Audio Ports	Audio input and headphone jack
Stand Assembly	Tilt adjustment mechanism
Back Cover	Plastic enclosure with ventilation

Technical Specifications

Display Size: 19 inches (48.26 cm)
Native Resolution: 1440 x 900 (WXGA+)
Brightness: 300 cd/m²
Contrast Ratio: 700:1
Response Time: 5ms
Viewing Angle: 170° horizontal, 160° vertical
Input Connectors: D-Sub, DVI-D
Audio: Built-in 1W x 2 speakers
Power Consumption: 40W max, <1W standby
Power Supply: 100-240V AC, 50/60Hz
Dimensions: 443.2 x 365.5 x 195 mm (with stand)
Weight: 4.2 kg

Disassembly Instructions

Follow these steps carefully for monitor disassembly:

Remove stand: Press release button and separate stand from monitor.
Remove back cover screws: Locate and remove all screws from rear casing.
Separate front and rear covers: Use plastic opening tools to carefully pry apart.
Disconnect internal cables: Detach LVDS cable, inverter cables, and control board connectors.
Remove metal shield: Unscrew and remove EMI shielding.
Access main boards: Power supply and main board are now accessible for service.

WARNING! Disconnect power before disassembly. Handle LCD panel with care to avoid damage.

Circuit Diagrams

Complete circuit schematics included for:

Power Supply Circuit (AC/DC conversion, voltage regulation)
Main Board Circuit (signal processing, microcontroller)
Inverter Circuit (backlight power supply)
Control Board Circuit (button interface, OSD control)
Audio Circuit (amplifier and speaker connections)

Note: Refer to separate schematic diagrams document for detailed circuit analysis.

Power Supply Unit

The PSU provides regulated DC voltages to all monitor components.

Output	Voltage	Current	Purpose
+5V	5V DC	2A	Main board logic circuits
+12V	12V DC	3A	Audio amplifier, backlight inverter
+3.3V	3.3V DC	1.5A	Microcontroller, memory

Common Issues: Capacitor bulging, fuse failure, MOSFET breakdown.

Main Board

The main board handles video signal processing and system control.

Main IC: MSTAR or equivalent scaler processor
Memory: 16MB DDR SDRAM
Flash ROM: 1MB for firmware storage
Input Processing: Analog-to-digital conversion for VGA input
Output: LVDS signal to LCD panel
OSD Controller: On-screen display generation

Service Note: Firmware updates available from LG service portal.

LCD Panel

Panel specifications and replacement guidelines:

Panel Model: LG Display LM190E08
Resolution: 1440 x 900 pixels
Backlight: CCFL lamps (x4)
Interface: LVDS 20-pin connector
Replacement: Use identical panel model for compatibility

CAUTION! Handle panel edges only. Avoid pressure on screen surface.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No power	Power cord, fuse, PSU	Check AC input, replace fuse, test PSU outputs
No display	Backlight, inverter, main board	Test backlight, check inverter voltage, verify main board operation
Distorted image	Cables, main board, panel	Reseat LVDS cable, test main board, check panel
No audio	Audio IC, speakers, cables	Check audio input, test speakers, verify audio IC operation
OSD not working	Control board, main board	Test buttons, check control board connection, replace main board

Parts List

Key replacement parts and their part numbers:

Part Description	Part Number
Main Board Assembly	EAX12345678
Power Supply Board	EAX12345679
LCD Panel	LM190E08
Inverter Board	EAX12345680
Control Board	EAX12345681
Stand Assembly	EAX12345682
Back Cover	EAX12345683
Front Bezel	EAX12345684

Safety Precautions

Essential safety measures for service technicians:

Always disconnect AC power before servicing
Discharge capacitors before handling power supply
Use anti-static wrist strap when handling circuit boards
Handle LCD panel with extreme care to avoid breakage
Ensure proper reassembly to maintain electrical safety
Verify all connections are secure before power application

WARNING! High voltage present in power supply and inverter circuits.

Service Information

For technical support and parts ordering:

LG Service Website: www.lgservice.com
Technical Support: 1-800-243-0000
Service Centers: Authorized LG service locations nationwide
Firmware Updates: Available through LG service portal
Warranty: 1 year parts and labor

Note: This manual is for qualified service technicians only.