8. Procedure for Measuring Microwave Energy Leakage. LG LRMM1430SW, LRMM1430SB

8. PROCEDURE FOR MEASURING MICROWAVE

ENERGY LEAKAGE

A. CAUTIONS

(1) Be sure to check a microwave emission prior to servicing the oven if the oven is operative prior to servicing.

(2) The service personnel should inform the manufacturer, importer, or assembler of any certified oven unit found to have a microwave emission level in excess of

5mW/cm.sq. and should repair any unit found to have excessive emission levels at no cost to the owner and should ascertain the cause of the excessive leakage.

The service personnel should instruct the owner not to use the unit until the oven has been brought into compliance.

(3) If the oven operates with the door open, the service personnel should;

- Tell the user not to operate the oven

- Contact the manufacturer and CDRH (Center for

Devices and Radiological Health) immediately.

NOTE: Address on CDRH

Office of Compliance (HFZ-312)

Center for Devices and Radiological Health

1390 Piccard Drive Rockville, Maryland 20850

(4) The service personnel should check all surface and vent openings for microwave emission testing.

(5) Check for microwave energy leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 1mW/cm.sq. And always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

NOTE: The standard is 5mW/cm.sq. while in the customer’s home. 1mW/cm.sq. stated here is manufacturer’s own voluntary standard for units in customer’s home.

EQUIPMENT

Electromagnetic energy leakage monitor (NARDA

8100B, HOLADAY HI 1501)

600cc glass beaker

Glass thermometer 100 0 C

B. MEASURING MICROWAVE ENERGY LEAKAGE

(1) Pour 275 15cc of 20 5 ˚C water in a beaker which is graduated to 600 cc, and place the beaker in the center of the oven.

(2) Set the energy leakage monitor to 2,450 MHz and use it following the manufacturer’s recommended test procedure to assure correct result.

(3) When measuring the leakage, always use the 2 inch

(5 cm) spacer supplied with the probe.

(4) Operate the oven at its maximum output.

(5) Measure the microwave radiation using and electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured. (See Figure 7)

Move probe along shaded area.

Probe scanning speed less than 2.5 cm/sec.

Figure 7

C. MEASUREMENT WITH THE OUT CASE REMOVED

(1) When you replace the magnetron, measure for microwave energy leakage before the outer case is installed and after all necessary components are replaced or adjusted. Special care should be taken in measuring the following parts.

- Around the magnetron

- The waveguide

WARNING: AVOID CONTACTING ANY HIGH VOLTAGE

PARTS.

Figure 6

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D. MEASUREMENT WITH A FULLY ASSEMBLED OVEN

(1) After all components, including the outer panels, are fully assembled, measure for microwave energy leakage around the door viewing window, the exhaust opening and air inlet openings.

(2) Microwave energy leakage must not exceed the values prescribed below.

NOTES:

Leakage with the outer panels removed - less than

5mW/cm.sq. Leakage for a fully assembled oven

(Before the latch switch (primary) is interrupted) with the door in a slightly opened position - less than 1 mW/cm

.sq.

E. NOTE WHEN MEASURING

(1) Do not exceed meter full scale deflection.

(2) The test probe must be removed no faster than 1 inch/sec (2.5cm/sec) along the shaded area, otherwise a false reading may result.

(3) The test probe must be held with the grip portion of the handle. A false reading may result if the operator’s hand is between the handle and the probe.

(4) When testing near a corner of the door, keep the probe perpendicular to the surface making sure the probe horizontally along the oven surface, this may possibly cause probe damage.

F. RECORD KEEPING AND NOTIFICATION AFTER

MEASUREMENT

(1) After adjustment and repair of any microwave energy interruption or microwave energy blocking device, record the measured values for future reference. Also enter the information on the service invoice.

(2) Should the microwave energy leakage not be more than 1mW/cm.sq. after determining that all parts are in good condition, functioning properly and genuine replacement parts which are listed in this manual have been used.

(3) At least once a year, have the electromagnetic energy leakage monitor checked for calibration by its manufacturer.

G. POWER OUTPUT MEASUREMENT

Be sure oven cavity is clean and cool .

(not used recently)

(1) Fill the test beaker with 59 ˚F(15 ˚C) ~ 75 ˚F(24 ˚C) 1 liter tap water.

(2) Stir the water in the beaker with thermometer (˚F or ˚C) and measure temperature as T1.

(3) Place the beaker on the center of turntable.

(4) Set for one (1) minute.

(5) When the heating is finished, stir the water again with thermometer and measure the temperature of water as T2.

(6) Subtract T1 from T2, this will give you the temperature rise.

(7) The microwave power output is within specification, if the temperature rise is as shown below:

Voltage

(VAC under load)

120V

108V

Temperature Rise

°C

13 - 15

11.5 - 13.5

°F

23.4 - 27

20.7 - 24.3

(8) Power output will be influenced by line voltage of power supply. Consequently, correct power output must be measured within 120V AC 1 Volt while unit is operating.

SPECIAL TIP

• This oven used the button head screws.

Button Head

(Torx style 2)

• When you remove the screws, using the tamper-resistant Torx driver have a pin-in-head.

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9. DISASSEMBLY INSTRUCTIONS

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELECTRICAL

OUTLET WHEN MAKING REPAIRS, RE-PLACEMENTS,

ADJUSTMENTS AND CONTINUITY CHECKS. WAIT AT

LEAST ONE MINUTE, UNTIL THE HIGH VOLTAGE

CAPACITOR IN THE HIGH VOLTAGE POWER SUPPLY

HAS FULLY DISCHARGED.

THE CAPACITOR SHOULD BE DISCHARGED BY USING

INSULATED WIRE - I.E. TEST PROBE CONNECTED TO

10K-OHM RESISTOR IN SERIES TO GROUND.

WHEN RECONNECTING THE WIRE LEADS TO

ANY PART, MAKE SURE THE WIRING CONNECTIONS

AND LEAD COLORS ARE CORRECTLY MATCHED

ACCORDING TO THE OVERALL CIRCUIT DIAGRAM.

(ESPECIALLY SWITCHES AND HIGH VOLTAGE

CIRCUIT.)

A. REMOVING OUT CASE (Figure 8)

(1) Unfasten five screws from the rear section.

(2) Unfasten two screws from the side section.

(3) Push the out case back about 1 inch (3cm).

(4) Lift the case from the set.

Remove deco front

Disconnect the lead wires

Remove choke cap

Choke Cap

Figure 8

B. DOOR ASSEMBLY REMOVAL (Figure 9)

(1) Remove out case.

(2) Unfasten two screws for removing deco front.

(3) Disconnect the lead wires from main board and pull that out from the cavity.

(4) Remove the choke cap very carefully with a flat-blade screw driver.

(5) Lift up and pull out Door assembly carefully from the cavity.

CAUTION: Be careful not to damage door seal plate with the screw driver.

Remove door

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Figure 9

C. REMOVING CONTROL CIRCUIT BOARD (Figure 10)

(1) Remove out case.

(2) Remove door assembly.

(3) Unfasten two screws.

(4) Lift up and pull out control panel assembly carefully from the cavity.

(5) Remove door frame.

(6) Remove the F.P.C connector from the terminal socket.

(7) Unfasten two screws which tighen the circuit board.

(8) Remove control circuit board from the door panel assembly.

Unfasten screws

Door frame securing

D. SEPARATE CAVITY AND BASE PLATE (Figure 11)

(1) Remove out case.

(2) Remove Door Assembly.

(3) Remove five screws at the base plate.

(Front 3 EA, Back 2 EA).

(4) Disconnect the lead wires from filter.

(5) Disconnect all the lead wires from main board.

(6) Disconnect the MGT high voltage lead wire and turn table motor lead wire.

(7) Lift up the cavity and disconnect the fan motor lead wire.

CAUTION: BE CAREFUL NOT TO DAMAGE LEAD

WIRE.

Unfasten screws

F.P.C.Connector

Control Panel

Figure 10

Remove screw

Circuit Board

Disconnect the lead wires

Figure 11

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E. AIR GUIDE REMOVAL (Figure 12)

(1) Separate cavity and base plate.

(2) Unfasten the screws which hold the air guide in the base plate.

(3) Unfasten the air guide from hook.

F. POWER BOARD AND INVERTER MODULE AND

SUCTION GUIDE (Figure 12)

(1) Separate cavity and base plate.

(2) Remove air guide.

(3) Unfasten the screws.

(4) Lift up the power board, inverter module and suction guide.

G. SENSOR DUCT REMOVAL (Figure 13)

(1) Remove out case.

(2) Unfasten the sensor duct screw.

(3) Disconnect sensor lead wire.

(4) Pull the sensor duct out.

Figure 13

Figure 12

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H. MAGNETRON REMOVAL

(1) Disconnect the leadwire from the magnetron.

(2) Carefully remove the mounting screws holding the magnetron at the waveguide.

(3) Remove the magnetron from the waveguide.

NOTE:

1. When removing the magnetron, make sure its dome does not hit any adjacent parts, or it may be damaged.

2. When replacing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition.

3. After replacing the magnetron, check for microwave leakage with a survey meter around the magnetron.

Microwave energy must be below the limit of 5 mW/cm 2 .

(With a 275 ml. water load).

Make sure that gasket is rigidly attached to the

magnetron. To prevent microwave leakage, tighten the mounting screws properly, making sure there is no gap between the waveguide and the magnetron.

I. REMOVING THE TURNTABLE MOTOR

(1) Remove the turntable and turntable roller rest.

(2) Lay the unit down on its back.

(3) Remove the turntable motor cover.

The turntable base cover is easily removed by pinching the four parts with a wire cutting.

(4) Disconnect the leadwire from the turntable motor terminals.

(5) Remove the screw securing the turntable motor to the oven cavity ASSEMBLY.

(6) After repairing the motor, rotate the removed turntable motor cover.

(7) Fit the turntable motor cover’s projecting part to the base plate slit.

NOTE:

1. Remove the lead wires from the turntable motor VERY

CAREFULLY.

2. Be sure to grasp the connector, not the wires, when removing.

Magnetron

Magnetron

Magnetron

Gasket

Waveguide

Bracket

Dome

Waveguide

Figure 14

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Lead Wires

Turntable Motor

Figure 15

J. FAN MOTOR ASSEMBLY REMOVAL

(1) Separate cavity and base plate.

(2) Remove air and suction guide..

(3) Remove the two screws holding the fan motor ASSEMBLY to the suction guide ASSEMBLY.

(4) Disconnect the wires and unfasten the screws.

(5) Pull out the Fan motor from the suction guide.

Inverter

Fan Motor ASS’Y

Suction

Guide

K. INTERLOCK SYSTEM

(1) INTERLOCK MECHANISM

The door lock mechanism is a device which has been specially designed to eliminate completely microwave activity when the door is opened during cooking and thus to prevent the danger resulting from the microwave leakage.

(2) MOUNTING OF THE PRIMARY/MONITOR/

SECONDARY SWITCHES TO THE LATCH BOARD

(3) INSTALLATION AND ADJUSTMENT OF THE LATCH

BOARD TO THE OVEN ASSEMBLY

• Mount the latch board to the oven assembly.

• Adjust the latch board in the arrow direction so that oven door will not have any play in it when the door is closed.

• Tighten the mounting screw.

• Check for play in the door by pushing the door release button. Door movement should be less than

0.5 mm. (1/64 inch)

Don't push the door release button while making this adjustment. Make sure that the latch moves smoothly after adjustment is completed and that the screws are tight.

Make sure the primary, monitor, and secondary switches operate properly by following the continuity test procedure.

ADJUSTMENT

DIRECTION

SECONDARY

SWITCH

Figure 16

MONITOR

SWITCH

PRIMARY

SWITCH

Figure 17

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