LG MB-309XED Service Manual

MICROWAVE OVEN

SERVICE MANUAL

MODEL : MB-309XED

CAUTION

BEFORE SERVICING THE UNIT, READ THE

SAFETY PRECAUTIONS IN THIS MANUAL.

SAFETY PRECAUTIONS

This device is to be serviced only by properly qualified service personnel.

Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to excessive microwave energy.

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY

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

B)Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary; (1) interlock operation, (2) proper door closing, (3) seal and sealing surfaces (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 shall be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.

CONTENTS

(Page)

SAFETY PRECAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Inside front cover SPECIFICATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 1-1 CAUTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2-1 INSTALLATIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 3-1 OPERATING INSTRUCTIONS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-1

FEATURES- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-1 CONTROL PANEL - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-1 OPERATING SEQUENCE- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-2 SCHEMATIC DIAGRAM - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-3 CIRCUIT DESCRIPTION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4-4

SERVICE INFORMATION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-1

TOOLS AND MEASURING INSTRUMENTS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-1 MICROWAVE LEAKAGE TEST - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-1 MEASUREMENT OF MICROWAVE POWER OUTPUT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-3 DISASSEMBLY AND ADJUSTMENT - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-3 INTERLOCK CONTINUITY TEST- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-8 COMPONENT TEST PROCEDURE - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-9 TROUBLE SHOOTING - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5-13

EXPLODED VIEW - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 6-1 REPLACEMENT PARTS LIST - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7-1 SCHEMATIC DIAGRAM OF P.C.B. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8-1

PRINTED CIRCUIT BOARD - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8-2

P.C.B. PARTS LIST - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9-1

SPECIFICATIONS

ITEM

DESCRIPTION

MODEL

MB-309XED

Power Requirement

220 Volts AC 50 Hz

MICROWAVE - - - - - - - - - - - - - -

- - - -

1,400 Watts (6.3A)

GRILL

- - - - -

- -

- - - - -

- - -

- - -

- - - -

- - -

1,000 Watts (4.5A)

Single phase, 3 wire grounded

Power Output

1,000 Watts full microwave power (IEC705)

Microwave Frequency

2,450 MHz

Magnetron

2M248

Timer

0 ~ 99 min. 99 sec.

Outside Dimensions

530mm (W) x 315mm (H) x 394mm (D)

Cavity Dimensions

348mm (W) x 222mm (H) x 373mm (D)

Net Weight

17.5 Kg (approx.)

Shipping weight

19.0 Kg (approx.)

Control Complement

Touch Control System

Clock : 1:00 - 12:59

Microwave Power for Variable Cooking

Power level

HIGH - - - - - - - - - -

- - - - - - -

- - - - -

- -

-

- - - -

- -

Full power throughout the cooking time

9

(Saute) - - - - - -

approx. 90% of Full power,

8 (Reheat) - - - - - - - -

approx. 80%

7 (Med.-High) - -

- - - - - - -

- - - - -

approx. 70%,

6 (Medium) - - - - - - - -

approx. 60%

5

(Med.-Low) - - -

- - - - - -

- - - - -

- approx. 50%,

4 (Defrost) - - - - - - - - -

approx. 40%

3 (Low) - - - - - - - - -

- - - - - -

- - - - -

approx. 30%,

2 (Simmer) - - - - - - - -

approx. 20%

1 (Warm) - - - - - - -

- - - - - -

- - - - -

approx. 10%

Nameplate Location

Back Side

Accessories

Owner's manual & cooking guide

Glass turntable

Rotating ring

Grill rack

This microwave oven is designed for household use only.

It is not recommended for commercial purposes.

1-1

CAUTIONS

Unlike other appliances, the microwave oven is high-voltage and high-current equipment. Though it is free from danger in ordinary use, extreme care should be taken during repair.

•DO NOT operate on a 2-wire extension cord during repair and use.

•NEVER TOUCH any oven components or wiring during operation.

•BEFORE TOUCHING any parts of the oven, always remove the power plug from the outlet.

•For about 30 seconds after the oven stops, an electric charge remains in the high voltage capacitor. When replacing or checking, you must discharge the high voltage capacitor by shorting across the two terminals with an insulated screwdriver.

•Remove your watches whenever working close to or replacing the Magnetron.

•DO NOT touch any parts of the control panel circuit. A resulting static electric discharge may damage this P.C.B.

•NEVER operate the oven with no load.

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

•NEVER put iron tools on the magnetron.

•NEVER put anything into the latch hole and the interlock switches area.

MICROWAVE RADIATION

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

Never look into an open waveguide or antenna while the device is energized.

•Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity. Never operate the magnetron unless it is properly installed.

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

ANTENNA

Gasket

COOLING FIN

FILAMENT

TERMINALS

MAGNETRON

CHASSIS GROUND

MAGNETRON

THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED SERVICE PERSONNEL.

2-1

INSTALLATIONS

BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.

INSTALLING

1.Empty the microwave oven and clean inside it with a soft, damp cloth. Check for damage such as misaligned door, damage around the door or dents inside the cavity or on the exterior.

2.Put the oven on a counter, table, or shelf that is strong enough to hold the oven and the food and utensils you put in it. (The control panel side of the oven is the heavy side. Use care when handling.)

3.Do not block the vent and the air intake openings. Blocking vent or air intake openings can cause damage to the oven and poor cooking results. Make sure the microwave oven legs are in place to ensure proper air flow.

4.The oven should not be installed in any area where heat and steam are generated, because they may damage the electronic or mechanical parts of the unit.

Do not install the oven next to a conventional surface unit or above a conventional wall oven.

5.Use microwave oven in an ambient temperature less than 104°F (40°C).

6.Place the microwave oven on a sturdy and flat surface at least 10 cm (4 inches) from the wall.

7.Place the microwave oven as far away as possible from TV, RADIO, COMPUTER, 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 electrical shock.

The plug must be plugged into an outlet that is properly installed and grounded.

WARNING

Improper use of the grounding plug can result in a risk of electric shock.

10cm

3-1

OPERATING INSTRUCTIONS

FEATURES

Oven Front Plate

Window Door Screen

Door Seal

Display Window

Control Panel

Door Open Button

Safety Door Lock System

Turntable

Grill Rack

Rotating Ring

CONTROL PANEL

14

Cocinado Al Toque

1	Papas Al Horno	Huevo	Pollo
	Palomitas	Arroz	Pizza
2	Grill	Programa	Combi	4
3		Personal
5	Tiempo		Potencia	6
8	Auto Descong	Inicio Rapido		7
	Por Peso
	1	2	3
9	4	5	6
	7	8	9
11	Mantener	0	Reloj	10
	Caliente
12	Parar/Borrar		Inicio	13

1.ONE TOUCH COOK: To select the desired auto cook setting.

2.GRILL

3.CUSTOM SET: You can select ON/OFF of beeper, automatic start or manual start of the one touch cook, and food weight measurement unit, pounds or kilograms.

4.COMBI

5.TIME ADJUSTMENT PADS: To set the cooking time.

6.POWER: To select the desired power level for cooking.

7.QUICK START: To set the cooking time and directly start.

8.AUTO WEIGHT DEFROST: To select the desired auto weight defrost programmed with weight pad.

9.NUMBER

10.CLOCK: To set the clock.

11.HOLD WARM: To keep the food warm after the cooking is done.

12.STOP/CLEAR: To stop oven and clear all entries except time of day.

13.START: One tap allows oven to begin functioning.

14. DISPLAY WINDOW: Provides indications of the functions selected, normally current time displayed.

4-1

OPERATING SEQUENCE

The following is a description of component functions during oven operation.

1. SETTING THE CLOCK

PARAR/BORRAR RELOJ NUMBER RELOJ

ex.) To set 4:30, touch number key [4],[3], and [0]. NOTE: 1) This is a 12 hour clock.

2)Clock will operate as long as power is applied to the oven.

2.CANCEL FUNCTION

Touch the PARAR/BORRAR pad whenever you need to cancel an entry or a function currently in use.

The display will either return to the last item entered or to the clock.

3. QUICK START

PARAR/BORRAR INICIO RAPIDO

4. ONE TOUCH COOKING

PARAR/BORRAR			PALOMITAS

NOTE: Heat only 1 package at a time

5. TIME COOKING

PARAR/BORRAR TIEMPO NUMBER POTENCIA

NUMBER INICIO

6. MULTI-STAGE COOKING

1ST STAGE

PARAR/BORRAR TIEMPO NUMBER POTENCIA NUMBER

2ND STAGE

TIEMPO NUMBER POTENCIA

NUMBER INICIO

7. AUTO WEIGHT DEFROST COOKING

			AUTO DESCONG				NUMBER OF
PARAR/BORRAR										INICIO
			POR PESO				WEIGHT

8. CHILD LOCK

This oven has a CHILD LOCK feature TO SET CHILD LOCK

• Touch the PARAR/BORRAR pad

•Touch and hold PARAR/BORRAR pad LOCK appear on the display.

TO CANCEL CHILD LOCK

• Touch the PARAR/BORRAR pad

•Touch and hold PARAR/BORRAR pad LOCK disappears.

9.CUSTOM SET

You can select ON/OFF of beeper, automatic start or manual start of the one touch cook, and food weight measurement unit, pounds of kilograms.

• Lbs/kg of beeper

			PROGRAMA
PARAR/BORRAR							1			INICIO
			PERSONAL
• To select automatic language selection
			PROGRAMA
PARAR/BORRAR							2			INICIO
			PERSONAL
• To select sound ON/OFF
			PROGRAMA
PARAR/BORRAR							3			INICIO
			PERSONAL
• To select language speed
			PROGRAMA
PARAR/BORRAR							4			INICIO
			PERSONAL

4-2

DIAGRAM SCHEMATIC

3-4

IMPORTANT SAFETY NOTE: THE SHADED AREAS ON THIS SCHEMATIC DIAGRAM INCORPORATE SPECIAL FEATURES IMPORTANT FOR PROTECTION FROM MICROWAVE RADIATION, FIRE, ELECTRICAL SHOCK, AND HAZARDS. WHEN SERVICING IT IS ESSENTIAL THAT ONLY MANUFACTURER'S SPECIFIED PARTS BE USED FOR THE CRITICAL COMPONENTS IN THE SHADED AREAS OF THE SCHEMATIC DIAGRAM.

NOTICE: SINCE THIS IS BASIC SCHEMATIC DIAGRAM, THE VALUES OF COMPONENTS AND

SOME PARTIAL CONNECTIONS ARE SUBJECT TO CHANGE FOR IMPROVEMENT.

CIRCUIT DESCRIPTION

GENERAL DETAILS

•The low voltage transformer supplies the necessary voltage to the micom controller when power cord is plugged in.

•When the door is closed, the primary switch is ON, the secondary switch is ON, and the monitor switch opens (contact COM and NO).

WHEN SELECTING COOKING POWER LEVEL AND TIME

•The micom controller memorizes the function you set.

•The time you set appears in the display window.

•Each indicator light turns on to indicate that the stage has been set.

WHEN TOUCHING THE START PAD

•The coil of the relay is energized by the micom controller.

•Power input is supplied to the high voltage transformer through the fuse to the primary switch and relay 2.

•Turntable rotates.

PRIMARY

SWITCH

FUSE

	L
	MONITOR	H.V.
	SWITCH	TRANS-
	N	FORMER
	RELAY 2	SECONDARY
		SWITCH

MICOM CONTROLLER

•The fan motor rotates and cools the magnetron by blowing the air (coming from the intake on the baseplate).

•The air is also directed into the oven to exhaust the vapor in the oven through the upper plate.

•Cooking time starts counting down.

•3.3 volts AC is generated from the filament winding of the high voltage transformer. This 3.3 volts is applied to the magnetron to heat the magnetron filament through two noise-preventing choke coils.

•A high voltage of approximately 2100 volts AC is generated in the secondary of the high voltage transformer which is increased by the action of the high voltage diode and charging of the high voltage capacitor.

•The negative 4,000 Volts DC is applied to the filament of the magnetron.

WHEN THE OVEN IS SET AT ANY LEVEL EXCEPT MAXIMUM.

•The micom controller controls the ON-OFF time of relay 2 by the applied signal to vary the average output power of microwave oven as POWER LEVEL.

(refer to page 1-1)

•One complete cycle of relay 2 is 22 seconds.

WHEN THE DOOR IS OPENED DURING COOKING

•Both the primary switch and relay 2 cut off the primary winding voltage of the high voltage transformer.

•ON-OFF of relay 2 is coupled electrically with opening and closing of the secondary switch.

•When the door is opened, the secondary switch is opened and when the door is closed, the secondary switch is closed.

•The cooking time stops counting down.

•Relay stops functioning.

•As the door is opened, if the contact of primary switch and relay2 and/or secondary switch fail to open, the fuse opens due to the large current surge caused by the monitor switch activation, which in turn stops magnetron oscillation.

FUSE

L
MONITOR	H.V.
SWITCH	TRANS-
N	FORMER
PRIMARY	SECONDARY
SWITCH RELAY 2	SWITCH
MICOM CONTROLLER

4-4

SERVICE INFORMATION

TOOLS AND MEASURING INSTRUMENTS

NECESSARY TOOLS

Tools normally used for TV servicing are sufficient. Standard tools are listed below.

•Diagonal pliers

•Long nose pliers

•Phillips screwdriver

•Flat blade screwdriver

•Wrench (size 5mm)

•Nutdriver (size 5mm)

•Adjustable wrench

•Soldering iron

•Solder

•Vinyl insulation tape

•Polishing cloth

NECESSARY MEASURING INSTRUMENTS

•TESTER (VOLTS-DC, AC, Ohmmeter)

•Microwave survey meter - Holaday HI-1500

HI-1501 - Narda 8100

8200

•Inch scale

•600 cc non conductive material beaker (glass or plastic),

inside diameter: approx. 8.5 cm (31/2 in.)

•Cylindrical and made of borosilicate glass vessel. max. thickness: 3 mm

outside diameter: approx. 190mm height: approx. 90mm

•Glass thermometer: 100°C or 212°F (1 deg scale)

MICROWAVE LEAKAGE TEST

CAUTIONS

•Be sure to check microwave leakage prior to servicing the oven if the oven is operative prior to servicing.

•The service personnel should inform the manufacture importer, or assembler of any certified oven unit found to have a microwave emission level in excess of 5 mW/cm2 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.

•If the oven operates with the door open, the service personnel should:

-Tell the user not to operate the oven.

-Contact the manufacturer.

•The service personnel should check all surface and vent openings for microwave leakage.

•Check for microwave leakage after every servicing. The power density of the microwave radiation leakage emitted by the microwave oven should not exceed

4 mW/cm2. Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage.

MEASURING MICROWAVE ENERGY LEAKAGE

•Pour 275±15cc of 20±5 °C(68±9 °F) water in a beaker which is graduated to 600 cc, and place the beaker on the center of the turntable.

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

•When measuring the leakage, always use the 2- inch (5cm) spacer supplied with the probe.

•Operate the oven at its maximum output.

•Measure the microwave radiation using and electromagnetic radiation monitor by holding the probe perpendicular to the surface being measured

Move probe along shaded area

Probe scanning speed Less than 2.5 cm/sec ( 1in/sec)

5-1

MEASUREMENT WITH OUTER CASE REMOVED

•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. (Circled area of Fig. below)

-Around the magnetron

-The waveguide

WARNING : AVOID CONTACTING ANY HIGH VOLTAGE PARTS

MEASUREMENT WITH A FULLY ASSEMBLED OVEN

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

•Microwave energy leakage must not exceed the values prescribed below.

NOTE: Leakage with the outer case removed less than 5 mW/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 2 mW/cm.sq.

NOTES WHEN MEASURING

•Do not exceed meter full scale deflection.

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

•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.

•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.

RECORD KEEPING AND NOTIFICATION AFTER MEASUREMENT

•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.

•The microwave energy leakage should not be more than 4 mW/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.

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

5-2

MEASUREMENT OF MICROWAVE POWER OUTPUT

•Microwave power output measurement is made with the microwave oven supplied at its rated voltage and operated at its maximum microwave power setting with a load of (1000±5) g of potable water.

•The water is contained in a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190mm.

•The oven and the empty vessel are at ambient temperature prior to the start of the test.

•The initial temperature (T1) of the water is (10±2)°C It is measured immediately before the water is added to the vessel. After addition of the water to the vessel, the load is immediately placed on the center of the turntable which is in the lowest position and the microwave power switched on.

•The time T for the temperature of the water to rise by a value ∆ T of (10±2)°K is measured, where T is the time in seconds and ∆ T is the temperature rise. The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is 5°K.

•The microwave power output P in watts is calculated from the following formula :

4187 x (∆ T)

P =

T

is measured while the microwave generator is operating at full power. Magnetron filament heat-up time is not included. (about 3 sec)

•The water is stirred to equalize temperature throughout the vessel, prior to measuring the final water temperature.

•Stirring devices and measuring instruments are selected in order to minimize addition or removal of heat.

WATER LOAD

TURNTABLE

DISASSEMBLY AND ADJUSTMENT

A. OUTER CASE REMOVAL

1)Disconnect the power supply cord from the outlet.

2)Remove the screws from the rear of the case.

The outer case must be moved backward to be lifted off.

B. POWER SUPPLY CORD

1)Remove the outer case.

2)Disconnect two terminals, and remove one screw of the ground terminal.

C. CONTROL PANEL ASSEMBLY

1)Open the door.

2)Disconnect the leadwire from RELAY (RY2) of the PCB SUB ASS’Y.

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

4)Disconnect the leadwire from connector (CN1) of the PCB SUB ASS’Y.

CAUTION: DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING

(refer to page 2-1)

Remove the screw

securing screw

ground screw

Lift up and pull out control panel

5-3