LG Flatron F700B Service Manual

The LG Flatron F700B is a 17-inch CRT monitor featuring a 0.24mm dot pitch, 1280x1024 maximum resolution, 110MHz video bandwidth, and advanced digital controls. This service manual covers technical specifications, disassembly procedures, circuit diagrams, troubleshooting, and maintenance guidelines for qualified service technicians.

1. Technical Specifications 2. Safety Precautions 3. Disassembly Procedures 4. Circuit Diagrams 5. Block Diagram 6. Adjustment Procedures 7. Troubleshooting Guide 8. Parts List 9. Waveforms 10. PCB Layouts 11. Service Notes

Technical Specifications

Complete technical specifications for the LG Flatron F700B CRT monitor.

ParameterSpecification
CRT Type17-inch Flat Square CRT
Viewable Area16.0-inch diagonal
Dot Pitch0.24mm
Maximum Resolution1280 x 1024 @ 60Hz
Recommended Resolution1024 x 768 @ 85Hz
Video Bandwidth110MHz
Horizontal Frequency30-70kHz
Vertical Frequency50-160Hz
Power Consumption100W maximum
Power Supply100-240V AC, 50/60Hz

Safety Precautions

Critical safety information for service technicians.

  1. Disconnect power before servicing: Always unplug monitor from AC outlet.
  2. High voltage discharge: CRT anode carries 25-30kV; discharge properly before handling.
  3. ESD protection: Use anti-static wrist strap when handling PCBs.
  4. Component replacement: Use exact replacement parts with correct ratings.

WARNING! High voltage present even after power off. CRT implosion hazard - handle with care.

Disassembly Procedures

Step-by-step disassembly instructions for service access.

  1. Remove base stand: Press release button and separate from monitor.
  2. Remove rear cover screws: 4 screws located on back housing.
  3. Separate front and rear covers: Use plastic tools to avoid damage.
  4. Disconnect internal cables: Note positions for reassembly.
  5. Remove deflection board: Disconnect high voltage connector first.

CAUTION! Mark cable positions. Avoid stressing CRT neck during disassembly.

Circuit Diagrams

Block Diagram

System block diagram showing signal flow and major components.

Input Stage: VGA connector → RGB signals → Video preamplifier

Processing: Microcontroller → Deflection processor → OSD generator

Output Stage: Horizontal output → Vertical output → High voltage generation

Power Supply: AC input → SMPS → Multiple DC outputs (+B, +12V, +5V, -12V)

Adjustment Procedures

Factory adjustment procedures using service mode.

  1. Enter service mode: Power off, hold MENU button, power on.
  2. Geometry adjustments: H-Size, H-Position, V-Size, V-Position.
  3. Convergence adjustment: Static and dynamic convergence settings.
  4. White balance: R-G-B cutoffs and drives for color temperature.
  5. Focus adjustment: Screen and focus potentiometers on flyback.

Tip: Record original settings before making adjustments.

Troubleshooting Guide

SymptomPossible CauseCorrective Action
No powerFuse, SMPSCheck AC fuse; test power supply outputs; replace bad capacitors.
No displayHigh voltage, CRTCheck EHT; test CRT heater; measure G1 voltage.
Horizontal collapseHorizontal outputTest horizontal output transistor; check deflection IC.
Vertical collapseVertical circuitCheck vertical output IC; test yoke connections.
Poor focusFocus circuitAdjust focus pot; check focus divider network.

Reset: Factory reset available in service menu.

Service: LG authorized service centers only.

Parts List

Critical replacement parts for service.

Part NumberDescriptionSpecification
F700B-CRTPicture Tube Assembly17" Flat Square
F700B-FBTFlyback TransformerOriginal replacement
F700B-HOTHorizontal Output TransistorBU2527AF
F700B-VOUTVertical Output ICTDA9302H
F700B-MCUMicrocontrollerWT62P1

Waveforms

Key test waveforms for troubleshooting.

  1. Horizontal output waveform: Check at collector of HOT.
  2. Vertical output waveform: Measure at output IC pin.
  3. B+ voltage: 50-150V depending on resolution.
  4. Video signals: RGB waveforms at CRT neck board.
  5. Sync signals: Horizontal and vertical sync inputs.

WARNING! Use high voltage probes for CRT anode measurements.

PCB Layouts

Printed circuit board layouts and component locations.

Service Notes

Important service technician notes and observations.

Common issues: Electrolytic capacitor failure in power supply, horizontal output transistor failure, focus potentiometer wear, yoke convergence drift.

Special tools required: High voltage probe, CRT rejuvenator, convergence tools, isolation transformer.

Calibration equipment: Pattern generator, color analyzer, high voltage meter.

NOTE: This manual is for qualified technicians only. Unauthorized service voids warranty.

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