This document is a service manual for the LG Microwave Oven, model MH-656EL. It provides comprehensive information for servicing the unit, including safety precautions, specifications, operating instructions, schematic diagrams, service procedures, and troubleshooting guides.
Function Description
The LG Microwave Oven MH-656EL is a household appliance designed for cooking, heating, and defrosting food using microwave energy. It also features a grill function and a combination mode, allowing for versatile cooking options. The oven operates on a single-phase, 3-wire grounded 230 Volts AC 50 Hz power supply.
Important Technical Specifications
- Power Requirement: 230 Volts AC 50 Hz, Single phase, 3 wire grounded.
- Power Output:
- Microwave: 900 Watts full microwave power (IEC705)
- Grill: 1,200W
- Combination: 2,500W
- Microwave Frequency: 2,450 MHz
- Magnetron: 2M214 - 39F
- Timer: 0 ~ 90 min.
- Outside Dimensions (W x H x D): 508 (W) x 303 (H) x 374 (D) mm
- Cavity Dimensions (W x H x D): 320 (W) x 233 (H) x 347 (D) mm
- Net Weight: 17 kg (approx.)
- Shipping Weight: 19 kg (approx.)
- Control Complement (Microwave Power for Variable Cooking):
- MAX: Full power throughout the cooking time
- MED.-HIGH: approx. 80% of Full power
- MEDIUM: approx. 60% of Full power
- DEFROST: approx. 40% of Full power
- LOW/WARM: approx. 20% of Full power
- Grill, COMBI
- Accessories: Owner's manual & Cooking guide, Glass turntable, Rotating ring, Grill rack.
Usage Features
The microwave oven offers a range of operating instructions and features for user convenience:
- Control Panel: The control panel includes indicators, auto cook functions, auto defrost, quick defrost, less/more time adjustment, weight adjustment, set clock, power level selection, grill, combi, dial, start, and stop/clear buttons.
- Operating Sequence: The manual details the steps for setting the clock, using the cancel function, quick start, microwave cooking, grill cooking, combi cooking, auto weight defrost, auto roast cook, and child lock.
- Cooking Modes:
- Microwave: Standard microwave cooking with variable power levels (MAX, MED.-HIGH, MEDIUM, DEFROST, LOW/WARM).
- Grill: For grilling food.
- Combination: Combines microwave and grill functions for faster and more thorough cooking.
- Defrost Functions: Auto weight defrost and quick defrost options are available.
- Safety Door Lock System: Ensures the door is securely closed during operation.
- Turntable and Rotating Ring: Ensures even cooking by rotating the food.
- Child Lock Feature: Prevents unintended operation by children.
Maintenance Features
The service manual provides detailed information for maintenance and troubleshooting, emphasizing safety precautions due to the presence of high voltage.
- Safety Precautions:
- Excessive Microwave Energy Exposure: Strict procedures must be followed to avoid exposure, including checking door seals, interlock switches, microwave source, and proper grounding.
- Microwave Radiation: Personnel should not be exposed to microwave energy. Never operate the device without a microwave energy absorbing load attached. Never look into an open waveguide or antenna while the device is energized.
- High Voltage Capacitor: Always discharge the high voltage capacitor before servicing the unit.
- Magnetron Gasket: Ensure the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron.
- Servicing by Qualified Personnel: The oven is to be serviced only by properly qualified service personnel.
- Tools and Measuring Instruments: A list of necessary tools is provided, including multimeters, microwave survey meters, and specific measuring instruments for checking microwave leakage.
- Microwave Leakage Test: Detailed instructions for performing a microwave leakage test using a microwave survey meter, including probe scanning speed and measurement areas.
- Measurement of Microwave Power Output: Procedures for measuring the microwave power output using a water load and a thermometer.
- Disassembly and Adjustment: Step-by-step guides for disassembling various components such as the outer case, power supply cord, door, fan motor, high voltage capacitor, high voltage transformer, turntable motor, and PCB assembly.
- Interlock Continuity Test: Procedures for checking the continuity of primary, monitor, and secondary interlock switches, crucial for safety.
- Component Test Procedure: Detailed tests for key components like the high voltage transformer, magnetron, high voltage capacitor, high voltage diode, fuse, heater element, grill thermostat, oven thermostat, magnetron thermostat, relays, fan motor, and turntable motor.
- Troubleshooting: Comprehensive flowcharts and tables for diagnosing common issues, including:
- Microwave oven not working.
- Low output power.
- Sparks occurring.
- Uneven cooking.
- Display issues (segments, numbers, random programming).
- Fuse blows.
- Fan motor or oven lamp not working.
- Low heat production.
- No microwave oscillation.
- Oven not cooking properly at set power level.
- Grill not operating or low temperature.
- Exploded View and Parts List: Detailed diagrams showing the exploded view of the oven, including door parts, control panel parts, oven cavity parts, latch board parts, interior parts, and base plate parts, along with corresponding part numbers for replacement.
- Schematic Diagrams: Electrical schematic diagrams of the main circuit and the PCB (Printed Circuit Board) to aid in understanding the electrical connections and troubleshooting.
This manual is essential for technicians to safely and effectively diagnose and repair the LG Microwave Oven MH-656EL, ensuring proper functioning and adherence to safety standards.
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