LG GR-J303UG Series User Manual

CAUTION
PLEASE READ CAREFULLY THE SAFETY PRECAUTIONS OF THIS MANUAL
BEFORE CHECKING OR OPERATING THE REFRIGERATOR.
KIMCHI REFRIGERATOR
SERVICE MANUAL
http://www.lgservice.com
MODEL : GR-J303UG*

LG GR-J303UG Series Specifications

General

Energy Star Certified	Yes
Ice Maker	Yes
Water Dispenser	Yes
Smart Diagnosis	Yes
Noise Level	39 dB
Color	Stainless Steel

Summary

SAFETY INSTRUCTIONS

1. PRODUCT SPECIFICATIONS

1-1. GR-J303UG*

Detailed specifications for the GR-J303UG model, including capacity, dimensions, and cooling system.

2. CIRCUIT DIAGRAM

3. MICOM FUNCTION AND EXPLANATIONS OF CIRCUITS

3-1. EXPLANATION OF FUNCTION

Details on various functions including display, storage, seasoning, flavor keeping, and temperature control.

3-2. EXPLANATION OF CIRCUITS

3-2-1. POWER CIRCUIT

Explanation of the power supply circuit, including rectification, switching, and feedback components.

3-2-2. OSCILLATION CIRCUIT

Details on the oscillation circuit for synchronization and clock generation within the MICOM.

3-2-3. RESET CIRCUIT

Explanation of the reset circuit for initializing the MICOM upon power application or failure.

3-2-4. LOAD/BUZZER DRIVE CRICUIT

Circuit diagrams for driving loads like fans, heaters, and the buzzer mechanism.

3-2-5. SWITCH INPUT CIRCUIT

Input circuits for detecting test switch signals and the reed switch for the single motor damper.

3-2-6. TEMPERATURE SENSING CIRCUIT

Details on upper, middle, lower, defrost, and ambient temperature sensors and their resistance characteristics.

3-2-7. TEMPERATURE SENSING CIRCUIT

Circuit for driving the single motor damper and detecting its open/close status via a reed switch.

3-2-8. STEPPING MOTOR DAMPER DRIVE CIRCUIT (FOR TEMPERATURE CONTROL AT MIDDLE COMPARTMENT)

Circuit for driving the middle compartment stepping motor damper, including control signals.

3-2-9. 3-WAY VALVE STEPPING MOTOR DRIVE CIRCUIT (FOR SWITCHING UPPER/MIDDLE/LOWER COMPARTMENT CYCLE)

Circuit for driving the 3-way valve stepping motor for compartment switching.

3-2-10. KEEPING TEMPERATURE COMPENSATION AND TOO COLD/ TOO WARM CUT COMPENSATION CIRCUIT

Circuits for temperature compensation and cut-off compensation for cold/warm conditions.

3-2-11. COMMUNICATION CIRCUIT BETWEEN MAIN PCB AND DISPLAY PCB

Circuitry for information exchange between the main MICOM and the display PCB MICOM.

3-3. SENSOR RESISTANCE CHARACTERISTICS TABLE

3-4. PCB PARTS DIAGRAM AND LIST

3-4-1. PWB(PCB) ASSEMBLY, MAIN

Diagram and list of components for the main Printed Circuit Board (PCB).

3-4-2. PWB(PCB) ASSEMBLY, DISPLAY [STANDARD]

Diagram and list of components for the display Printed Circuit Board (PCB).

3-5. PCB CIRCUIT DIAGRAM

3-5-1. PWB (PCB) ASSEMBLY, MAIN CIRCUIT DIAGRAM (LED MODULE TYPE)

Circuit diagram for the main Printed Circuit Board (PCB) assembly, LED module type.

3-5-2. PWB (PCB) ASSEMBLY, DISPLAY CIRCUIT DIAGRAM

Circuit diagram for the display Printed Circuit Board (PCB) assembly.

4. EXPLODED VIEW AND SERVICE PARTS LIST

4-1. EXPLODED VIEW

Exploded view illustration of the refrigerator components for service identification.