LG 50PT350 Service Manual

The LG 50PT350 is a 50-inch Plasma TV featuring HD resolution, built-in digital/analog tuner, multiple HDMI inputs, USB connectivity, component video inputs, composite AV inputs, Ethernet port, headphone jack, remote control, energy saving modes, picture/audio adjustments, and smart TV functionality. Below are key sections for technical specifications, disassembly procedures, circuit diagrams, troubleshooting, and repair guidelines.

Technical Specifications

Key components: Plasma display panel, power supply board, main board, logic board, sustain boards, buffer boards, and remote control.

Specification	Details
Screen Size	50 inches Plasma
Resolution	1366 x 768 HD
TV System	ATSC/NTSC/Clear QAM
Power Consumption	280W typical, 0.5W standby
Inputs	3x HDMI, 2x USB, Component, Composite, RF
Outputs	Digital audio optical, headphone
Power Supply	100-240V AC, 50/60Hz
Operating Temp	0°C to 40°C
Dimensions	1210 x 750 x 89 mm (with stand)
Weight	24.5 kg

Safety Precautions

Critical safety information for service personnel.

1. Disconnect AC power before servicing.
2. Use proper grounding techniques when handling boards.
3. Plasma panels contain high voltage - discharge properly.
4. Use anti-static precautions for all electronic components.

WARNING! High voltage present in power supply and sustain boards - risk of electric shock. Always discharge capacitors before servicing.

Disassembly Procedures

Step-by-step instructions for accessing internal components.

1. Remove stand: Lay TV face down on soft surface, remove screws securing stand.
2. Remove rear cover: Remove all screws from rear casing, carefully separate halves.
3. Access power supply: Disconnect all cables, remove mounting screws.
4. Remove main board: Disconnect ribbon cables and connectors, remove screws.
5. Access panel components: Remove shielding and thermal pads as needed.

CAUTION! Plasma panel is fragile - handle with care to avoid cracking.

Circuit Diagrams

• Power Supply Circuit: EAX64905501 - Primary and secondary circuits
• Main Board Circuit: EAX64905401 - Signal processing and control
• Logic Board Circuit: EAX64905301 - Panel driving signals
• Sustain Boards: X and Y sustain circuit diagrams
• Buffer Boards: Upper and lower buffer circuits

PCB Layouts

Detailed board layouts with component identification.

Power Supply Board: Component locations, test points, connector pinouts.

Main Board: IC locations, memory chips, processor, input/output connectors.

Logic Board: LVDS connections, timing controller, voltage regulators.

Sustain Boards: Power components, heat sinks, driver circuits.

Voltage Measurements

Standard operating voltages at key test points.

1. Power Supply Outputs: VS: 195V, VA: 55V, 15V, 5V, 3.3V
2. Main Board: 3.3V_STBY, 2.5V, 1.8V, 1.2V
3. Logic Board: 3.3V, 1.8V, VSCAN: -95V
4. Sustain Boards: VSUS: 195V, VSETUP: 195V

Tip: Use high-impedance multimeter for accurate measurements.

Troubleshooting Flowcharts

Systematic approach to common problems.

Symptom	Diagnostic Steps	Solutions
No Power	Check AC input, standby voltage, power board outputs	Replace power supply board, check fuses
No Picture/Sound	Verify main board operation, check LVDS signal	Replace main board, check cables
Abnormal Colors	Test buffer boards, check sustain voltages	Replace buffer boards, adjust VSCAN
Image Retention	Run panel maintenance, check aging patterns	Replace panel if severe
Audio Problems	Check audio IC, speaker connections	Replace main board, speakers

Replacement Parts List

Genuine LG replacement parts with part numbers.

1. Power Supply Board: EAX64905501
2. Main Board: EAX64905401
3. Logic Board: EAX64905301
4. X Sustain Board: EAX64905201
5. Y Sustain Board: EAX64905101
6. Upper Buffer Board: EBT62996601
7. Lower Buffer Board: EBT62996501
8. Remote Control: AKB72915207

WARNING! Use only genuine LG parts for reliable operation and safety.

Adjustment Procedures

Factory calibration and adjustment methods.

VS Voltage Adjustment: Adjust RV801 for 195V ±2V

VA Voltage Adjustment: Adjust RV802 for 55V ±1V

VSCAN Adjustment: Adjust for -95V ±3V

White Balance: Use service remote for RGB adjustments

Geometry: Adjust overscan and positioning

Firmware Update

Software update procedures for main board.

1. Download latest firmware from LG service website.
2. Copy to USB drive formatted as FAT32.
3. Insert USB while TV is in standby mode.
4. TV will automatically detect and install update.
5. Do not power off during update process.

CAUTION! Interrupted firmware update may brick the main board.

Service Mode Access

Accessing hidden service menus for diagnostics.

Function	Access Method	Purpose
Service Menu	Menu-0000 on remote	Basic adjustments
Engineering Menu	Menu-0413 on remote	Advanced settings
Burn-in Reduction	Menu-8741 on remote	Panel maintenance
Factory Reset	Menu-0000 > Reset	Restore defaults

Reset: Service Menu > Option > Factory Reset

Service Support: 1-800-243-0000; www.lgservice.com