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LG Flatron F775FT User Manual

LG Flatron F775FT
38 pages
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COLOR MONITOR
SERVICE MANUAL
Website:http://biz.LGservice.com
E-mail:http://www.LGEservice.com/techsup.html
CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
MODEL: F775FT(FB775H-EL)
CHASSIS NO. : CA-124
FACTORY MODEL: FB775H
*( ) ID LABEL Model No.
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LG Flatron F775FT Specifications

General IconGeneral
Display TypeCRT
Maximum Resolution1280 x 1024
Refresh Rate85 Hz
Aspect Ratio5:4
Dot Pitch / Pixel Pitch0.25 mm
Max Resolution1280 x 1024
Horizontal Refresh Rate30 - 95 kHz
Vertical Refresh Rate50 - 160 Hz
Input SignalAnalog RGB
Weight40.1 lbs
Dot Pitch0.25 mm
Screen Size17 inches
Viewable Size16 inches

Summary

SAFETY PRECAUTIONS

SAFETY CHECK

Guidelines for servicing the color monitor, focusing on high voltage circuits.

FIRE & SHOCK HAZARD

Precautions regarding isolation transformers, lead dress, protective devices, and soldering.

IMPLOSION PROTECTION

Care needed to avoid damage to display tubes and their protection systems during installation.

X-RADIATION

Measures to prevent X-radiation by keeping high voltage at factory-recommended levels.

TIMING CHART

OPERATING INSTRUCTIONS

Power ON/OFF Button

Button used to turn the monitor ON and OFF.

Power Indicator

Indicator light color changes based on monitor status (normal, saving, abnormal).

SET Button

Button to enter a selection in the on-screen display.

OSD Select/Adjustment

Controls for navigating and adjusting on-screen display menus.

OSD Button

Button to enter or exit the on-screen display.

CONTROL LOCATIONS

WIRING DIAGRAM

BLOCK DIAGRAM

DESCRIPTION OF BLOCK DIAGRAM

Line Filter & Associated Circuit

Filters noise from the power input line and prevents interference with other appliances.

Degauss Circuit & Coil

Eliminates abnormal color by degaussing the screen's shadow mask when the monitor is turned on.

SMPS (Switching Mode Power Supply)

Converts AC input voltage to various DC voltages required by monitor circuits.

X-ray Protection

Monitors high voltage and stops horizontal drive if it exceeds safety limits to prevent X-radiation.

Micom (Microprocessor) Circuit

Manages monitor operations, settings, and user adjustments via OSD.

Horizontal and Vertical Oscillation

Generates horizontal and vertical pulses for CRT deflection using H and V sync signals.

D/D (DC to DC) Converter

Steps up DC voltage from the SMPS to supply the horizontal deflection output circuit.

Side-Pincushion & Trapezoid Correction Circuit

Improves screen distortion by correcting side-pincushion and trapezoid effects.

Horizontal Deflection Output Circuit

Drives the horizontal deflection yoke with a saw-tooth current for horizontal sweep.

High Voltage Output & FBT (Flyback Transformer)

Generates high voltage for the CRT anode, focus, and screen.

H-Linearity Correction Circuit

Corrects horizontal linearity based on the horizontal sync frequency.

Vertical Output Circuit

Drives the vertical deflection yoke with a ramp wave for vertical sweep.

Dynamic Focus Output Circuit

Maintains focus clarity across the screen by adjusting beam focus dynamically.

H & V Blanking and Brightness Control

Controls retrace line elimination and screen brightness via G1 voltage.

Block Diagram Descriptions

Image Rotation (Tilt) Circuit

Corrects screen tilt by supplying a signal to the tilt coil near the deflection yoke.

Video Pre-Amp Circuit

Amplifies the analog video signal to prepare it for further processing.

Video Output Amp Circuit

Amplifies the video signal for application to the CRT cathode.

ADJUSTMENT

ADJUSTMENT PROCEDURE & METHOD

Details on installing equipment and running alignment programs for monitor adjustments.

Adjustment for High-Voltage

Procedure to adjust the high voltage to the factory-recommended level of 25.8kV.

Adjustment for Factory Mode (Preset Mode)

Steps for setting factory presets, including clearing EEPROM and adjusting various parameters.

Adjustment for White Balance and Luminance

Guides for adjusting white balance, color bias, and luminance using specific patterns and meters.

ADVANCED ADJUSTMENTS

Input EDID Data

Procedure to write EDID data to the EEPROM for monitor identification and configuration.

Adjustment for Focus

Steps to adjust the focus controls on the FBT for optimal screen clarity.

TROUBLESHOOTING GUIDE

NO POWER

Flowchart to diagnose and identify causes of the monitor not powering on.

NO CHARACTER

Flowchart to diagnose and identify causes of no image or characters appearing on the screen.

NO RASTER

Flowchart to diagnose and identify causes of no display output (raster) on the screen.

NO HORIZONTAL DEFLECTION

Flowchart to diagnose and identify causes of missing horizontal image deflection.

TROUBLE IN H-LINEARITY

Flowchart to diagnose and identify causes of horizontal linearity problems and related Cs signal table.

NO VERTICAL DEFLECTION

Flowchart to diagnose and identify causes of missing vertical image deflection.

TROUBLE IN OSD

Flowchart to diagnose and identify causes of issues with the On-Screen Display (OSD) functionality.

TROUBLE IN DPM

Flowchart to diagnose and identify issues related to the Digital Power Management (DPM) mode.

NO DEGAUSSING

Flowchart to diagnose and identify causes of the degaussing function not working correctly.

NO TILT (NO ROTATION)

Flowchart to diagnose and identify causes of the screen tilt or rotation function not working.

EXPLODED VIEW

EXPLODED VIEW PARTS LIST

REPLACEMENT PARTS LIST

PIN CONFIGURATION

STV6888 IC Block Diagram

STV9211 IC Pin Configuration and Description

STV9211 IC Block Diagram

STV9556 IC Pin Configuration and Block Diagram

SCHEMATIC DIAGRAM

PRINTED CIRCUIT BOARD LAYOUTS

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