LG LMVM2033SB (01) PDF DOCUMENT

To avoid possible exposure to excessive microwave energy, please adhere to the following precautions before and during servicing:

a. Do not operate or allow the oven to be operated with the door open.

b. Before activating the magnetron or other microwave source, perform the following safety checks and make repairs as necessary: (1) Interlock operation, (2) proper door closing, (3) seal and sealing surfaces (checking for arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.

c. Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.

d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and transmission systems must be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.

e. A microwave leakage check to verify compliance with the federal performance standard should be performed on each oven prior to release to the owner.

Additionally, note these important cautions:

• The LG LMVM2033SB microwave oven is a high-voltage and high-current appliance. Extreme care should be taken during repair.

• Do not operate on a 2-wire extension cord.

• NEVER touch any oven components or wiring during operation.

• Before touching any parts of the oven, always remove the power plug from the outlet.

• Do not touch any parts of the control panel circuit, as a static electric discharge may damage the P.C.B.

• Never operate the oven with no load.

• Never injure the door seal and front plate of the oven cavity.

• Personnel should not be exposed to microwave energy which may radiate from the magnetron if it is improperly used or connected. All input and output microwave connections, waveguide, flange, and gasket must be secure. Never operate the device without a microwave energy absorbing load attached.

• Be sure that the magnetron gasket is properly installed around the dome of the tube whenever installing the magnetron.

• The oven is to be serviced only by properly qualified service personnel.

PRECAUTIONS ON INSTALLATION

A. Plug the power supply cord into a 120V AC, 60Hz, single-phase power source with a capacity of at least 20 amperes.

B. Avoid placing the unit in a location where there is direct heat or splashing water.

C. Install the unit on the mounting plate firmly.

D. Place the unit as far away as possible from TV, radio, etc. to prevent interference.

GROUNDING INSTRUCTIONS

For personal safety, this appliance must be fully grounded at all times. In the event of an electrical short circuit, grounding reduces the risk of electric shock. The plug must be plugged into an outlet that is properly installed and grounded. This unit is equipped with a 3-prong plug for your safety. If the wall outlet is a grounded 3-hole type, the unit will be grounded automatically. Improper use of the grounding plug can result in a risk of electric shock. Do not, under any circumstances, cut or remove the third ground prong from the power cord plug.

The operation of the primary, secondary, and monitor interlock switches depends on whether the door is open or closed. The following table details the status of each switch:

1. AUTO REHEAT: Press this button to reheat dinner plate, soup/sauce, casserole, roll/muffin.

2. AUTO COOK: Press this button to cook fresh vegetables, frozen vegetables, rice, or casseroles.

3. POPCORN: Press this button when popping popcorn in your microwave oven.

4. DEFROST: Touch this button to defrost frozen food.

5. SOFTEN: Press this button to soften butter, ice cream, cream cheese, or frozen juice.

6. MELT: Press this button to melt butter or margarine, chocolate, cheese, or marshmallows.

7. CUSTOM COOK: Touch this button to make oven remember Cook time and Power level.

8. POWER LEVEL: Press this button to select a cooking power level.

9. DISPLAY: The Display includes a clock and indicators to tell you the time of day, cooking time settings and cooking functions selected.

10. NUMBER: Press this button to enter cooking time, power level, quantities or weights.

11. +, –: Touch this button to add or subtract ten seconds of cooking time each time you touch it.

12. ADD 30 SEC: Press this button to control the add 30sec. cook time.

13. START/ENTER: Press this button to start a function. If you open the door after oven begins to cook, press START/ENTER again.

14. LIGHT HIGH/LOW/OFF: Touch this button to turn the cooktop/countertop light on high/low or off.

15. KIDS MEAL: Select type of dish to reheat HOT DOG, MAC & CHEESE or CHICKEN NUGGETS.

16. CLOCK: Press this button to enter the time of day.

17. TIMER: Press this button to set a timer.

18. COOK TIME: Press this button to set a cooking time.

19. CUSTOM SET: Touch this pad to change the oven’s default setting for sound, clock, display speed, and defrost weight.

20. TURNTABLE ON/OFF: Press this button to turn the turntable on or off.

21. ENERGY SAVING: Press this button to save energy.

22. STOP/CLEAR: Press this button to stop the oven or clear all entries.

23. VENT ON/OFF: Touch button to turn the vent on slow or off.

24. VENT 4 SPEED: Touch button to change vent speed.

25. VENT AUTO TIMESET: Touch this button to set ventilation time (1, 3, 5, 10, and 30 minutes.)

You can perform a self-diagnosis to check the humidity sensor and PCB thermistor. Follow these steps:

1. Press “Defrost weight/time” for 2 seconds. The unit will display “TEST” and beep once.

2. The unit will check if the PCB humidity sensor and PCB thermistor are short or open.

3. If it finds an error, it will beep and display an error code.

4. If the unit is normal, it will beep and display “PASS”.

5. Press “Clear” to return to Standby mode.

The following error codes may be displayed:

A. Never operate the unit when it is empty. Operating the oven with no load may shorten the life of the magnetron. Whenever cooking dry foods (dried fish, bread, etc.) or a small amount of food, be sure to put a glass of water into the cooking compartment. The glass turntable may become hot after operating, be careful when touching it.

B. Aluminum foil should be avoided because it will disrupt cooking and may cause arcing. However, small pieces may be used to cover some parts of food to slow the cooking. Any aluminum foil used should never be closer than 1 in. (2.5 cm) to any side wall of the oven.

After installation, the following sequences and results should be checked carefully:

A. Put a container filled with water (about 1 liter) into the oven, and close the door tightly.

B. Set cooking time for 10 minutes by touching 1 and then 0 three times. 1, 0, 0, 0 appears in the display window.

C. Press the START button. Make sure the cavity light comes on. The unit will begin cooking and the display window will show the time counting down by seconds.

D. After about 5 minutes, make sure the primary interlock switch, the secondary interlock switch and the interlock monitor switch operate properly by opening and closing the door several times. Press the START button each time the door is closed.

E. Continue operating the unit. Two short beeps and one long beep will sound when the time is up. The unit will shut off automatically.

F. Confirm the water is hot.

If the display does not operate and there is no beeping sound when you push a key, follow these steps:

1. Check Connector to PCB: Ensure the connector is securely attached to the main circuit board (PCB). If it’s loose or disconnected, reconnect it.

2. Check Power Cord Continuity: Test for continuity between the prongs of the power cord and the connector pins that attach to the noise filter.

3. Check Fuse: Check the main fuse for continuity. If there is no continuity, the fuse has blown and needs to be replaced.

4. Check Noise Filter: Test for continuity between the input and output terminals of the noise filter. If there is no continuity, the noise filter may be faulty.

5. Replace PCB: If all the above components are working correctly, the main PCB (Part No. EBR75341201) may need to be replaced.

If the keys on your LG LMVM2033SB do not operate, follow this procedure:

1. Check START Key: With the door closed, check if only the START key and EZ-ON keys operate. If they do but other keys don’t, proceed to the next steps.

2. Check Latch Board Switch: With the door closed, perform a continuity test on the secondary interlock switch on the latch board. If there is no continuity (beeping sound), you may need to adjust the latch board.

3. Check Door Sensor Voltage: Open the door and check the voltage of the door sensing part on the main PCB (CN3 Pin1 and Pin2). It should be over 4V. If not, the PCB (EBR75341201) may need replacement.

4. Check Connector: Ensure the keypad connector is securely attached to the PCB. If it is disconnected or loose, reconnect it.

5. Check Keypad: If the connector is fine, the keypad itself might be faulty and require replacement.

6. Replace PCB: If all other steps fail to resolve the issue, the PCB (EBR75341201) may need to be replaced.

If your LG LMVM2033SB operates (light is on, turntable rotates) but does not heat, follow these troubleshooting steps:

1. Reset by Opening Door: Open and close the door at least three times to reset the interlock system. Check if the product operates correctly. Sometimes, if something is caught in the door or sealing area, the latch and monitor switches will prevent operation for safety.

2. Check Relay Voltage: While the product is operating (e.g., under EZ-ON start), check if the voltage across the D35 diode on the PCB is over 8V. If not, the PCB (EBR75341201) may be faulty.

3. Check Latch Board: With the door closed, perform a continuity test on the primary latch switch. If there is no continuity, adjust the latch board.

4. Check High Voltage Components: If the above steps do not resolve the issue, the problem likely lies within the high voltage section. This includes the High Voltage Transformer, High Voltage Capacitor, High Voltage Diode, and the Magnetron. These components should only be tested and replaced by a qualified technician due to the risk of electric shock. Check for disconnected connectors and test the resistance of each component against its specified range.

If the turntable motor on your LG LMVM2033SB does not work, perform the following checks:

1. Check Oven Lamp: When the door is closed and you start a cycle, does the oven lamp turn on? If it does not, the issue may be with the primary latch board. Adjusting the latch board may resolve the issue.

2. Check Voltage to Turntable Motor Relay: Push the EZ-ON button to operate the oven. Check if the voltage across the D37 diode on the PCB is over 8V. If it is not, the PCB (EBR75341201) is likely faulty and needs replacement.

3. Check Turntable Motor Relay (RY1): Perform a continuity test between the two pins of relay RY1. If there is no continuity, the PCB (EBR75341201) needs replacement.

4. Check Turntable Motor: If the relay is receiving voltage and shows continuity, but the turntable still doesn’t operate, the turntable motor itself may be faulty and need replacement.

If the LG LMVM2033SB turns on automatically without pushing the start key, follow these troubleshooting steps:

1. Reset Door: Repeat opening and closing the door at least three times. This can reset the system if an interlock switch is stuck. A potential cause is something caught in the door, preventing safe operation.

2. Check Latch Board: With the door closed, perform a continuity test on the secondary switch of the latch board. If there is no continuity, the latch board may need adjustment.

3. Check Oven Lamp: With the door closed, check if the oven lamp turns on. If it does not, the turntable motor may be faulty.

4. Check Door Sensor Voltage: When the door is opened, check if the voltage of the door sensing part (Pin 11 to Pin 12 on the connector) is over 4V. If not, the PCB (EBR75341201) needs to be replaced.

5. Check Relay Voltage: Check if the voltage of both ends of the D37 diode on the PCB is over 8V. If not, the PCB (EBR75341201) needs to be replaced.

6. Check Relay Continuity: Perform a continuity test between the two pins of relay RY1. If there is continuity when there shouldn’t be, the PCB (EBR75341201) may be faulty. If there is no issue with continuity, there is likely no problem with the PCB for this symptom.

The continuity of the three interlock switches (Primary, Monitor, and Secondary) is tested to ensure they are functioning correctly for safety. After disconnecting the wire leads from each switch, an ohmmeter is used to check the circuit between the terminals in both door open and door closed conditions.

NOTE: After checking the continuity of the switches, make sure that they are connected correctly. This test is crucial after any repair to the door or interlock system.

Testing components requires disconnecting the power and, for high-voltage parts, discharging the capacitor. These tests should be performed by a qualified technician.

To test the touch key board of the LG LMVM2033SB, you need to measure the resistance between the terminal pins of the FPC (Flexible Printed Circuit) KEY CONNECTOR. When a key is touched, the resistance should be low, and when not touched, it should be very high.

NOTE: When reconnecting the FPC connector, make sure that the holes on the FPC connector are properly engaged with hooks on the plastic fastener.