LG AS991 Service Manual

The LG AS991 is a professional service device designed for technical maintenance and repair operations. This service manual provides comprehensive information for qualified technicians including safety procedures, technical specifications, disassembly instructions, troubleshooting guides, and maintenance procedures. Below are key sections for safety, technical specifications, service procedures, and troubleshooting.

1. Safety Precautions 2. Technical Specifications 3. Disassembly Procedures 4. Component Layout 5. Test Points and Measurements 6. Troubleshooting Flowcharts 7. Replacement Parts List 8. Maintenance Procedures 9. Calibration Instructions 10. Regulatory Compliance 11. Service Contact Information

Safety Precautions

Before performing any service procedures, read and understand all safety warnings and precautions.

Warning Type	Description
Electrical Safety	Disconnect power before servicing. Use insulated tools.
ESD Protection	Use anti-static wrist strap and mat when handling components.
High Voltage	Capacitors may retain charge; discharge before servicing.
Mechanical Safety	Wear safety glasses when disassembling components.
Laser Safety	Do not look directly into laser components during service.
Chemical Safety	Handle cleaning solvents and adhesives in well-ventilated areas.

Technical Specifications

Model: LG AS991
Power Requirements: 100-240V AC, 50/60Hz
Operating Temperature: 0°C to 40°C
Storage Temperature: -20°C to 60°C
Dimensions: 300mm x 200mm x 150mm
Weight: 2.5 kg
Input/Output Ports: USB, Ethernet, HDMI, Audio I/O
Processor: Quad-core 2.0 GHz
Memory: 4GB RAM, 64GB Storage

Disassembly Procedures

Follow these steps carefully for proper disassembly and reassembly.

Power off and disconnect all cables from the device.
Remove the rear cover screws (8x Phillips #1).
Carefully separate the rear cover from the main chassis.
Disconnect internal ribbon cables and connectors.
Remove motherboard mounting screws and lift board carefully.
Access individual components as needed for replacement.

WARNING! Document screw locations and cable orientations for proper reassembly.

Component Layout

Main board components and their locations for service reference.

Component	Location	Function
Main Processor	U1	Central processing unit
Memory IC	U2, U3	RAM modules
Power Management	U4	Voltage regulation
Audio Codec	U5	Audio processing
Network Controller	U6	Ethernet interface
USB Controller	U7	USB port management

Test Points and Measurements

Critical test points for voltage and signal measurements during troubleshooting.

TP1: +3.3V standby (should measure 3.3V ±5%)
TP2: +5V main power (should measure 5.0V ±5%)
TP3: +12V power rail (should measure 12.0V ±5%)
TP4: Clock signal (should show 25MHz square wave)
TP5: Reset signal (should be high during normal operation)

Note: Use calibrated digital multimeter and oscilloscope for accurate measurements.

Troubleshooting Flowcharts

Systematic approach to diagnosing common issues.

Symptom	Diagnostic Steps	Solution
No Power	Check AC input, fuse, power supply voltages	Replace faulty power components
No Display	Verify video signal, backlight, LCD connections	Replace display assembly or video IC
Audio Issues	Test audio outputs, check codec IC, speakers	Replace audio components or speakers
Network Failure	Check Ethernet port, network IC, drivers	Replace network controller or update firmware
Overheating	Monitor temperatures, check fans, thermal paste	Clean vents, replace thermal compound

Replacement Parts List

Authorized replacement parts with part numbers.

Main Board Assembly: EAX65432101
Power Supply Board: EAX65432102
Display Panel: EAX65432103
Front Bezel: EAX65432104
Cooling Fan: EAX65432105
AC Adapter: EAX65432106
Remote Control: EAX65432107
Stand Assembly: EAX65432108

Maintenance Procedures

Routine maintenance to ensure optimal performance.

Quarterly cleaning of internal components and vents
Annual replacement of thermal compound on processor
Bi-annual calibration of display and audio outputs
Regular firmware updates from manufacturer website
Periodic inspection of cables and connectors

CAUTION! Power off and disconnect before performing any maintenance.

Calibration Instructions

Professional calibration procedures for technical accuracy.

Display calibration using colorimeter and calibration software
Audio calibration with reference microphone and test tones
Network calibration for optimal data transfer rates
Power calibration for stable voltage outputs
Sensor calibration for environmental monitoring

Regulatory Compliance

This device complies with international standards and regulations.

FCC Part 15 Class B
CE Marking (European Conformity)
RoHS Compliant
WEEE Directive
Energy Star Certified

Service Contact Information

For technical support and service inquiries:

Service Type	Contact Method	Availability
Technical Support	1-800-LG-SERVICE	Mon-Fri 8AM-8PM EST
Parts Ordering	parts.lgservice.com	24/7 Online
Service Centers	Locator on LG website	By Appointment
Online Support	www.lg.com/support	24/7

Emergency Service: Available for critical business applications.