LG Flatron 21 Inch TV Service Manual

The LG Flatron 21-inch TV is a professional-grade CRT television featuring 21-inch flat screen display, 480i resolution, built-in NTSC tuner, multiple input options including composite video, S-Video, component video, and RF antenna input. Includes advanced service modes, geometry adjustments, convergence controls, white balance calibration, and comprehensive troubleshooting procedures for professional technicians.

1. Technical Specifications 2. Safety Precautions 3. Disassembly Procedures 4. Circuit Diagrams 5. Test Points & Measurements 6. Adjustment Procedures 7. Troubleshooting Flowcharts 8. Parts List 9. Service Modes 10. Replacement Procedures 11. Warranty Information

Technical Specifications

Complete technical specifications for LG Flatron 21-inch CRT television.

Parameter	Specification
Screen Size	21 inches (diagonal)
Display Type	Flat Square CRT
Resolution	480i (SDTV)
TV System	NTSC
Inputs	RF, Composite, S-Video, Component
Power Requirements	120V AC, 60Hz, 85W
Dimensions	19.7" W × 17.3" H × 18.9" D
Weight	55.1 lbs
Chassis	MC-051A
CRT Type	A68QCP891X

Safety Precautions

Critical safety procedures for service technicians.

Disconnect AC power before servicing.
Use isolation transformer when testing live circuits.
CRT contains high voltage - discharge anode before handling.
Handle CRT with care to avoid implosion hazard.
Use proper grounding techniques.

WARNING! High voltage up to 30kV present. CRT implosion hazard. Always follow safety protocols.

Disassembly Procedures

Step-by-step disassembly instructions.

Remove rear cover screws (8 total).
Carefully separate front bezel from chassis.
Disconnect all internal connectors.
Remove deflection board and power supply.
CRT removal requires special handling procedure.

CAUTION! Mark all connectors before disassembly. Handle CRT with extreme care.

Circuit Diagrams

Power Supply: Switching mode power supply schematic.
Deflection Circuit: Horizontal and vertical deflection circuits.
Video Amplifier: RGB video amplifier stages.
Audio System: Audio amplifier and processing circuits.
Tuner/IF: RF tuner and intermediate frequency circuits.
Microcontroller: System control and interface circuits.
Convergence: Dynamic convergence adjustment circuits.

Test Points & Measurements

Critical test points and expected voltage measurements.

Test Point	Normal Voltage	Tolerance
B+ Voltage	130V DC	±5V
Horizontal Output	1000V P-P	±50V
CRT Anode	25-28kV	±2kV
Focus Voltage	4-6kV	±0.5kV
Vertical Output	50V P-P	±5V

Adjustment Procedures

Factory adjustment procedures for optimal performance.

Screen Voltage: Adjust SCREEN control for retrace lines just visible.
Focus: Adjust FOCUS for sharpest center image.
Geometry: Use service mode for size, linearity, pincushion.
Convergence: Static and dynamic convergence adjustments.
White Balance: RGB cutoff and drive adjustments.
Color Purity: Degauss and purity ring adjustments.

Tip: Use crosshatch and color bar patterns for accurate adjustments.

Troubleshooting Flowcharts

Diagnostic flowcharts for common service issues.

Symptom	Diagnostic Steps	Common Causes
No Power	Check fuse, bridge rectifier, switching transistor	Fuse, power IC, startup circuit
No Picture/Sound	Check B+, horizontal output, microcontroller	Horizontal output transistor, flyback
Poor Geometry	Check vertical IC, geometry components	Vertical IC, capacitors, yoke
Color Problems	Check CRT voltages, video processing	CRT drivers, video IC, color circuit
Convergence Issues	Check convergence board, magnets	Convergence IC, purity rings

Parts List

Critical replacement parts with manufacturer part numbers.

CRT: A68QCP891X (LG Original)
Flyback Transformer: FBT-2587A
Horizontal Output: 2SD2536
Vertical IC: LA7845
Power IC: STR-F6654
Microcontroller: TMP87CM36N
Video Processor: TB1238AN
Audio IC: TDA7265

Service Modes

Accessing and using service modes for adjustments.

Enter Service Mode: Press VOL DOWN on TV and MENU on remote simultaneously.
Navigation: Use CH UP/DOWN to select menu, VOL UP/DOWN to adjust values.
Geometry Menu: H-SIZE, V-SIZE, LINEARITY, PINAMP, PINPHA
White Balance: R-CUT, G-CUT, B-CUT, R-DRV, G-DRV, B-DRV
Video Settings: BRIGHT, CONTRAST, COLOR, TINT, SHARPNESS
Exit: Press POWER to save and exit service mode.

WARNING! Record original values before making changes. Incorrect settings may require factory reset.

Replacement Procedures

Step-by-step component replacement instructions.

CRT Replacement: Requires special tools and safety procedures.
Flyback Replacement: Discharge anode, remove old unit, install new.
Yoke Replacement: Carefully remove old yoke, align new yoke precisely.
Board Replacement: Transfer all settings and adjustments.
Convergence Assembly: Precise alignment required after replacement.

CAUTION! Always use manufacturer-specified replacement parts.

Warranty Information

LG warranty terms and service center information.

Limited warranty: 1 year parts and labor on chassis. 3 years on CRT. Service must be performed by authorized LG service centers. For technical support, contact LG Electronics Service Division at 1-800-243-0000 or visit www.lgservice.com. Keep original purchase receipt for warranty validation.