Sharp R-330DW, R-330DK User Manual

R - 330DK

R -330DW

SERVICE MANUAL

S3005R330DPW/

MICROWAVE OVEN

MODELS R-330DK

R-330DW

In the interest of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
R-330DW
WARNING TO SERVICE PERSONNEL: Microwave ovens con-
tain circuitry capable of producing very high voltage and
current, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Recti-
fier Assembly, High Voltage Harness etc..)
TABLE OF CONTENTS
	Page
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ...................	INSIDE FRONT COVER
BEFORE SERVICING ......................................................................................................	INSIDE FRONT COVER
WARNING TO SERVICE PERSONNEL ................................................................................................................	1
MICROWAVE MEASUREMENT PROCEDURE ...................................................................................................	2
FOREWORD AND WARNING ...............................................................................................................................	3
PRODUCT SPECIFICATIONS ..............................................................................................................................	4
GENERAL INFORMATION ...................................................................................................................................	4
OPERATION ..........................................................................................................................................................	6
TROUBLESHOOTING GUIDE ............................................................................................................................	10
TEST PROCEDURE ............................................................................................................................................	12
TOUCH CONTROL PANEL .................................................................................................................................	21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................	26
PICTORIAL DIAGRAM ........................................................................................................................................	32
POWER UNIT CIRCUIT ......................................................................................................................................	33
CPU UNIT CIRCUIT ............................................................................................................................................	34
INDICATOR CIRCUIT ..........................................................................................................................................	35
PRINTED WIRING BOARD .................................................................................................................................	36
PARTS LIST ........................................................................................................................................................	37
PACKING AND ACCESSORIES .........................................................................................................................	41

SHARP CORPORATION

This document has been published to be used for after sales service only.

The contents are subject to change without notice.

R -330DK

R-330DW

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.

(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.

BEFORE SERVICING

Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement Procedure outlined in this service manual.

If microwave emissions level is in excess of the specified limit, contact SHARP ELECTRONICS CORPORATION immediately @1-800-237-4277.

If the unit operates with the door open, service person should 1) tell the user not to operate the oven and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's Center for Devices and Radiological Health immediately.

Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found with emissions in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance.

R -330DK

R-330DW

WARNING TO SERVICE PERSONNEL

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in a severe, possibly fatal, electrical shock.

(Example)

High Voltage Capacitor, High Voltage Power Trans-

former, Magnetron, High Voltage Rectifier Assem-

bly, High Voltage Harness etc.. Read the Service Manual carefully and follow all

instructions.

Don't Touch ! Danger High Voltage

Before Servicing

1.Disconnect the power supply cord Â, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

WARNING:RISK OF ELECTRIC SHOCK. DISCHARGE THE HIGH-VOLTAGE CAPACITOR BEFORE SERVICING.

The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then short-circuit the connection of the highvoltage capacitor (that is the connecting lead of the highvoltage rectifier) against the chassis with the use of an insulated screwdriver.

Whenever troubleshooting is performed the power supply must be disconnected. It may, in some cases, be necessary to connect the power supply after the outer case has been removed, in this event,

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Disconnect the leads to the primary of the power transformer.

5.Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.

6.After that procedure, reconnect the power supply cord.

When the testing is completed,

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Reconnect the leads to the primary of the power transformer.

5.Reinstall the outer case (cabinet).

6.Reconnect the power supply cord after the outer case is installed.

7.Run the oven and check all functions.

After repairing

1.Reconnect all leads removed from components during testing.

2.Reinstall the outer case (cabinet).

3.Reconnect the power supply cord after the outer case is installed.

4.Run the oven and check all functions.

Microwave ovens should not be run empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven turntable, close the door and set the power to HIGH and set the microwave timer for two (2) minutes. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out Before Servicing procedure and reexamine the connections to the component being tested.

When all service work is completed and the oven is fully assembled, the microwave power output should be checked and a microwave leakage test should be carried out.

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MICROWAVE MEASUREMENT PROCEDURE

A. Requirements:

1)Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven should not exceed 1mW/cm2 at any point 5cm or more from the external surface of the oven, measured prior to acquisition by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm2 at any point 5cm or more from the external surface of the oven.

2)Safety interlock switches Primary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of the requirement as above mentioned, secondary interlock switch shall prevent microwave radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface of the oven.

B. Preparation for testing:

Before beginning the actual measurement of leakage, proceed as follows:

1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.

Important:

Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.

2)Place the oven tray in the oven cavity.

3)Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5˚C (68˚F) in the center of the oven cavity.

The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic.

The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage is measured accurately.

4)Set the cooking control on Full Power Cooking Mode.

5)Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed, replace it with 275 ml of cool water.

C. Leakage test:

Closed-door leakage test (microwave measurement)

1)Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.

2)Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication on the meter.

3)Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal has been breached (eg., around the switches, indicator, and vents).

While testing for leakage around the door pull the door away from the front of the oven as far as is permitted by the closed latch assembly.

4)Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm2, and that the secondary interlock switch does turn the oven OFF before any door movement.

NOTE: After servicing, record data on service invoice and microwave leakage report.

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SERVICE MANUAL

MICROWAVE OVEN

R-330DK/ R-330DW

FOREWORD

This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service Information for the SHARP MICROWAVE OVEN, R-330DK, R-330DW.

It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory customer service.

Check the interlock switches and the door seal carefully. Special attention should be given to avoid electrical shock and microwave radiation hazard.

WARNING

Never operate the oven until the following points are ensured.

(A)The door is tightly closed.

(B)The door brackets and hinges are not defective.

(C)The door packing is not damaged.

(D)The door is not deformed or warped.

(E)There is no other visible damage with the oven.

Servicing and repair work must be carried out only by trained service personnel.

DANGER

Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing. Service personnel - Do not contact the following parts while the appliance is energized;

High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness;

If provided, Vent Hood, Fan assembly, Cooling Fan Motor.

All the parts marked “*” on parts list are used at voltages more than 250V.

Removal of the outer wrap gives access to voltage above 250V.

All the parts marked “ ” on parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

SHARP ELECTRONICS CORPORATION

SHARP PLAZA, MAHWAH,

NEW JERSEY 07430-2135

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R-330DW

PRODUCT DESCRIPTION

GENERAL INFORMATION

OPERATION

TROUBLESHOOTING GUIDE AND TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WIRING DIAGRAM

PARTS LIST

R- 330DK

R-330DW

	SPECIFICATION
ITEM		DESCRIPTION
Power Requirements	120 Volts / 14 Amperes
	60 Hertz
	Single phase, 3 wire grounded
Power Output	1150 watts (IEC TEST PROCEDURE)
	Operating frequency of 2450MHz
Case Dimensions	Width 20-1/2"
	Height 11-7/8"
	Depth 17-1/8"
Cooking Cavity Dimensions	Width 14-3/4"
	Height 8-3/4"
1.2 Cubic Feet	Depth 15-3/4"
Control Complement	Touch Control System
	Clock ( 1:00 - 12:59 )
	Timer (0 - 99 min. 99 seconds)
	Microwave Power for Variable Cooking
	Repetition Rate;
	100 PERCENT .................................	Full power throughout the cooking time
	90 PERCENT ......................................................	approx. 90% of Full Power
	80 PERCENT ......................................................	approx. 80% of Full Power
	70 PERCENT ......................................................	approx. 70% of Full Power
	60 PERCENT ......................................................	approx. 60% of Full Power
	50 PERCENT ......................................................	approx. 50% of Full Power
	40 PERCENT ......................................................	approx. 40% of Full Power
	30 PERCENT ......................................................	approx. 30% of Full Power
	20 PERCENT ......................................................	approx. 20% of Full Power
	10 PERCENT ......................................................	approx. 10% of Full Power
	0 PERCENT ......................................	No power throughout the cooking time
	Sensor Cooking pad, Breakfast Bar pad, Lunch on the Run pad
	One Dish Dinners pad, Super Defrost pad, Compu Defrost pad
	Beverage Center pad, Number selection pads
	Kitchen Timer pad, Clock pad, Minute Plus pad
	Power Level pad, Stop/Clear pad, Start touch On pad
Oven Cavity Light	Yes
Safety Standard	UL Listed	FCC Authorized
	DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J

GENERAL INFORMATION

GROUNDING INSTRUCTIONS

This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed and grounded in accordance with the National Electrical Code and local codes and ordinances.

In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the electric current.

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

Electrical Requirements

The electrical requirements are a 120 volt 60 Hz, AC only,

15 or 20 amp. fused electrical supply. It is recommended that a separate circuit serving only this appliance be provided. When installing this appliance, observe all applicable codes and ordinances.

A short power-supply cord is provided to reduce risks of becoming entangled in or tripping over a longer cord.

Where a two-pronged wall-receptacle is encountered, it is the personal responsibility and obligation of the customer to

4

contact a qualified electrician and have it replaced with a properly
grounded three-pronged wall receptacle or have a grounding adapter				3-Pronged Plug Grounded
properly grounded and polarized. If the extension cord must be used, it					Receptacle Box
should be a 3-wire, 15 amp. or higher rated cord. Do not drape over a
countertop or table where it can be pulled on by children or tripped over
accidentally.
CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR RE-				Grounding Pin
	MOVE THE ROUND GROUNDING PRONG FROM THIS
	PLUG.			3-Pronged Receptacle
1.	Door open handle.	OVEN DIAGRAM
	Pull to open door.				7
2.	Door latches.		6
	The oven will not operate unless the
	door is securely closed.			9
3.	Removable turntable support.
4.	Removable turntable.		5	8	12
	The turntable will rotate clockwise or		10 11
		2
	counterclockwise.	1
5.	Oven lamp.
	It will light when oven is operating or		10. Coupling.		4
	door is opened.				3
6.	Oven door with see-through window.		11. Wave guide cover.
7.	Ventilation openings. (Rear)		12. Power supply cord
8.	Auto-Touch control panel.			TOUCH CONTROL PANEL
9.	Time display: Digital display, 99
	minutes 99 seconds.

NOTE:

The directed features are disabled after one minute when the oven is not in use. These features are automatically enabled when the door is opened and closed or the STOP/ CLEAR pad is pressed.

R -330DK

R-330DW

See note.

See note.

See note.

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OPERATION

DESCRIPTION OF OPERATING SEQUENCE

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

OFF CONDITION

Closing the door activates the door sensing switch and secondary interlock switch. (In this condition, the monitor switch contacts are opened.)

When oven is plugged in, 120 volts A.C. is supplied to the control unit (Figure O-1).

1.The display will show "SHARP SIMPLY THE BEST PRESS CLEAR AND PRESS CLOCK".To set any program or set the clock, you must first touch the STOP/ CLEAR pad. The display will clear, and " : " will appear.

COOKING CONDITION

Program desired cooking time by touching the NUMBER pads. Program the power level by touching the POWER LEVEL pad and then a Number pad.

When the START pad is touched, the following operations occur:

1.	The contacts of relays are closed and components
		connected to the relays are turned on as follows.
		(For details, refer to Figure O-2)
		RELAY	CONNECTED COMPONENTS
		RY-1	oven lamp/turntable motor/fan motor
		RY-2	power transformer
2.	120 volts A.C. is supplied to the primary winding of the
		power transformer and is converted to about 3.1 volts
		A.C. output on the filament winding, and approximately
		2370 volts A.C. on the high voltage winding.
3.		The filament winding voltage heats the magnetron
		filament and the H.V. winding voltage is sent to a voltage
		doubler circuit.
4.	The microwave energy produced by the magnetron is
		channelled through the waveguide into the cavity feed-
		box, and then into the cavity where the food is placed to
		be cooked.
5.		Upon completion of the cooking time, the power
		transformer, oven lamp, etc. are turned off, and the
		generation of microwave energy is stopped. The oven
		will revert to the OFF condition.
6.	When the door is opened during a cook cycle, the
		monitor switch, door sensing switch, secondary interlock
		switch, relay (RY1) and primary interlock relay are
		activated with the following results. The circuits to the
		turntable motor, the cooling fan motor, and the high
		voltage components are de-energized, the oven lamp
		remains on, and the digital read-out displays the time still
		remaining in the cook cycle when the door was opened.
7.	The monitor switch electrically monitors the operation of
		the secondary interlock switch and primary interlock
		relay and is mechanically associated with the door so
		that it will function in the following sequence.

(1)When the door opens from the closed position, the primary interlock relay (RY2) and secondary interlock switch open their contacts. And contacts of the relay (RY1) remains closed. Then the monitor switch contacts close.

(2)When the door is closed from the open position, the monitor switch contacts open first. Then the contacts of the secondary interlock switch and door sensing switch close. And contacts of the relay (RY1) open.

If the secondary interlock switch and primary interlock relay (RY2) fail with the contacts closed when the door is opened, the closing of the monitor switch contacts will form a short circuit through the monitor fuse, secondary interlock switch, relay (RY1) and primary interlock relay (RY2), causing the monitor fuse to blow.

POWER LEVEL 0 PERCENT TO 90 PERCENT COOKING

When Variable Cooking Power is programmed, the 120 volts A.C. is supplied to the power transformer intermittently through the contacts of relay (RY-2) which is operated by the control unit within a 32 second time base. Microwave power operation is as follows:

VARI-MODE	ON TIME	OFF TIME
100 PERCENT	32 sec.	0 sec.
90 PERCENT	30 sec.	2 sec.
80 PERCENT	26 sec.	6 sec.
70 PERCENT	24 sec.	8 sec.
60 PERCENT	22 sec.	10 sec.
50 PERCENT	18 sec.	14 sec.
40 PERCENT	16 sec.	16 sec.
30 PERCENT	12 sec.	20 sec.
20 PERCENT	8 sec.	24 sec.
10 PERCENT	6 sec.	26 sec.
0 PERCENT	0 sec.	32 sec.

Note: The ON/OFF time ratio does not correspond with the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

SENSOR COOKING CONDITION

Using the SENSOR function, the food is cooked without figuring time, power level or quantity. When the oven senses enough steam from the food, it relays the information to its microprocessor which will calculate the remaining cooking time and power level needed for best results. When the food is cooked, water vapor is developed. The sensor “senses” the vapor and its resistance increases gradually. When the resistance reaches the value set according to the menu, supplementary cooking is started. The time of supplementary cooking is determined by experiment with each food category and inputted into the LSI.

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An example of how sensor works: (POTATOES)

1.Potates at room temperature. Vapor is emitted very slowly. MICROWAVE

2. Heat Potates. Moisture and humidity is emitted rapidly. You can smell the aroma as it cooks.

AH SENSOR

MICROWAVE

3.Sensor detects moisture and humidity and calculates cooking time and variable power.

Cooking Sequence.

1.Touch one of the SENSOR pads. And then touch the Start pad.

NOTE: The oven should not be operated on SENSOR immediately after plugging in the unit. Wait two minutes before cooking on SENSOR.

2.The coil of shut-off relay (RY-1) is energized, the turntable motor, oven lamp and cooling fan motor are turned on, but the power transformer is not turned on.

3.After about 16 seconds, the cook relay (RY-2) is energized. The power transformer is turned on, microwave energy is produced and first stage is started. The 16 seconds is the cooling time required to remove any vapor from the oven cavity and sensor.

NOTE: During this first stage, do not open the door or touch STOP/CLEAR pad.

4.When the sensor detects the vapor emitted from the food, the display switches over to the remaining cooking time and the timer counts down to zero.

At this time, the door may be opened to stir, turn, or season food.

5.When the timer reaches zero, an audible signal sounds. The shut-off relay and cook relay are de-energized and the power transformer, oven lamp, etc. are turned off.

6.Opening the door or touching the STOP/CLEAR pad, the time of day will reappear on the display and the oven will revert to an OFF condition.

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SCHEMATIC

NOTE: CONDITION OF OVEN

1.DOOR CLOSED

2.CLOCK APPEARS ON DISPLAY

MONITOR			THERMAL		THERMAL
FUSE 20A			CUT-OUT (OVEN)		CUT-OUT (MG.)

				N.O.				POWER
						N.O.
A2								TRANSFORMER
						F3
A1		(RY-1)		(RY-2)		F2	SENSOR
					PRIMARY
					INTERLOCK
					RELAY			CAPACITOR0.94 F
GRN		COM.		SH-B	SH-A	F1	AH		2300VAC
CONTROL UNIT				COM.
120V AC					DOOR
60 Hz
					SENSING		MONITOR
					SWITCH
							SWITCH
OL	OVEN	TTM	FM					RECTIFIER
	LAMP
									MAGNETRON
		TURN-		FAN
		TABLE
				MOTOR
	SECONDARY	MOTOR
	INTERLOCK
	SWITCH

Figure O-1. Oven Schematic-Off Condition

SCHEMATIC

NOTE: CONDITION OF OVEN

1.DOOR CLOSED

2.COOKING TIME PROGRAMMED

3.VARIABLE COOKING CONTROL "HIGH"

4."START" PAD TOUCHED

MONITOR					THERMAL	THERMAL
FUSE 20A					CUT-OUT (OVEN)	CUT-OUT (MG.)

				N.O..				POWER
						N.O.
A2								TRANSFORMER
						F3
A1		(RY-1)		(RY-2)		F2	SENSOR
					PRIMARY
					INTERLOCK
					RELAY			CAPACITOR0.94 F
GRN		COM		SH-B	SH-A	F1	AH		2300VAC
CONTROL UNIT				COM.
120V AC					DOOR
60 Hz
					SENSING		MONITOR
					SWITCH
							SWITCH
OL	OVEN	TTM	FM					RECTIFIER
	LAMP
									MAGNETRON
		TURN-		FAN
		TABLE
				MOTOR
	SECONDARY	MOTOR
	INTERLOCK
	SWITCH

Figure O-2. Oven Schematic-Cooking Condition

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DESCRIPTION AND FUNCTION OF COMPONENTS

DOOR OPEN MECHANISM

The door is opened by pulling the door. Refer to the Figure D-1.

Door

	Latch Hook
Latch	Door Sensing
Heads	Switch

Monitor Switch

Secondary

Interlock Switch

Figure D-1. Door Open Mechanism

CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH, PRIMARY INTERLOCK RELAY (RY2), RELAY (RY1), SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER "TEST PROCEDURE").

NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY.

TURNTABLE MOTOR

The turntable motor rotates the turntable located on the bottom of the oven cavity, so that the foods on the turntable cook evenly during cooking. The turntable may turn in either direction.

COOLING FAN MOTOR

DOOR SENSING AND SECONDARY INTERLOCK SWITCHES

The secondary interlock switch is mounted in the lower position of the latch hook and the door sensing switch in the primary interlock system is mounted in the upper position of the latch hook. They are activated by the latch heads on the door. When the door is opened, the switches interrupt the power to all high voltage components. A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches. The primary interlock system consists of the door sensing switch and primary interlock relay located on the control circuit board.

MONITOR SWITCH

The monitor switch is activated (the contacts opened) by the latch head on the door while the door is closed. The switch is intended to render the oven inoperative, by means of blowing the monitor fuse, when the contacts of the primary interlock relay (RY2) and secondary interlock switch fail to open when the door is opened.

Functions:

1.When the door is opened, the monitor switch contact close (to the ON condition) due to their being normally closed. At this time the primary interlock relay (RY2) and secondary interlock switch are in the OFF condition (contacts open) due to their being normally open contact switches.

2.As the door goes to a closed position, the monitor switch contacts are first opened and then the door sensing switch and the secondary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)

3.If the door is opened, and the primary interlock relay (RY2) and secondary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing of the monitor switch contacts.

The cooling fan motor drives a blade which draws external cool air. This cool air is directed through the air vanes surrounding the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and vapors given off from the heating foods. It is then exhausted through the exhausting air vents at the oven cavity.

MONITOR FUSE

1.The monitor fuse blows when the contacts (COM-NO) of the primary interlock relay (RY2) and secondary interlock switch remain closed with the oven door open and when the monitor switch closes.

2.If the wire harness or electrical components are shortcircuited, this monitor fuse blows to prevent an electric shock or fire hazard.

OVEN THERMAL CUT-OUT

The thermal cut-out, located on the top of the oven cavity, is designed to prevent damage to the oven by fire. If the food load is overcooked, by either error in cook time or defect in the control unit, the thermal cut-out will open.

Under normal operation, the oven thermal cut-out remains closed. However, when abnormally high temperatures are reached within the oven cavity, the oven thermal cut-out will open at 257˚F(125˚C), causing the oven to shut down.

MAGNETRON THERMAL CUT-OUT

The thermal cut-out located near the magnetron is designed to prevent damage to the magnetron if an over heated condition develops in the tube due to cooling fan failure, obstructed air guide, dirty or blocked air intake, etc.

Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the magnetron, the thermal cut-out will open at 293˚F(145˚C) causing the oven to shut down.

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TROUBLESHOOTING GUIDE

Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.

When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which will be found in the "Test Procedure "section.

IMPORTANT: If the oven becomes inoperative because of a blown monitor fuse, check the monitor switch, relay (RY1) primary interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the monitor fuse. If the monitor fuse is replaced, the monitor switch must also be replaced. Use part FFSBA021WRK0 as an assembly.

IMPORTANT: Whenever troubleshooting is performed with the power supply cord disconnected. It may, in some cases, be necessary to connect the power supply cord after the outer case has been removed, in this event,

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Disconnect the leads to the primary of the power transformer.

5.Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.

6.After that procedure, reconnect the power supply cord.

When the testing is completed

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Reconnect all leads removed from components during testing.

5.Reinstall the outer case (cabinet).

6.Reconnect the power supply cord after the outer case is installed.

7.Run the oven and check all functions.

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CK = Check / RE = Replace

TEST PROCEDURE

RE RE A B

C D

E

F

F

G H RE RE CK

I CKCK CK J

K

L M

N

CONDITION

PROBLEM

POSSIBLE CAUSE AND DEFECTIVE PARTS

SHORT IN POWER CORD

SHORT OR OPENED WIRING

MAGNETRON

POWER TRANSFORMER

H.V. RECTIFIER ASSEMBLY

HIGH VOLTAGE CAPACITOR

THERMAL CUT-OUT

PRIMARY INTERLOCK SYSTEM

SECONDARY INTERLOCK SWITCH

MONITOR SWITCH

MONITOR FUSE

OVEN LAMP OR SOCKET

COOLING FAN MOTOR

TURNTABLE MOTOR

TOUCH CONTROL PANEL

WRONG OPERATION

LOW VOLTAGE

DIRTY OVEN CAVITY

KEY UNIT

RELAY (RY1)

COMPU DEFROST

FOIL PATTERN ON PWB.

AH SENSOR

Home fuse or circuit breaker blows

when power cord is plugged into wall

receptacle

Monitor fuse blows when power cord

is plugged into wall receptacle.

OFF

All letters and indicators do not ap-

CONDITION

pear in display when power cord is

first plugged into wall outlet.

Display does not operate properly

when STOP/CLEAR key is touched.

(Buzzer should sound and ":" or time

of day should appear in display.)

Oven lamp does not light when door

is opened.

Oven lamp does not go out when

door is closed.

Oven lamp lights but fan motor and

turntable motor do not operate.

Oven does not go into cook cycle

when START pad is touched

Oven seems to be operating but little

or no heat is produced in oven load.

(Food incompletely cooked or not

cooked at all at end of cook cycle.)

COOKING

Oven goes into a cook cycle but

CONDITION

extremely uneven heating is pro-

duced in oven load (food).

Oven does not cook properly when

programmed for Cooking Power 50

PERCENT mode. (Operates prop-

erly on Cooking Power 100 PER-

CENT mode.)

Oven goes into COMPU DEFROST

but food is not defrosted well.

AH sensor does not end during Sen-

SENSOR

sor cooking condition. (Oven does

COOKING

not shut off after a cup of water is

CONDITION

boiling by sensor cooking.)

Oven stops at 16 sec. after starting.

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R- 330DK

R-330DW

TEST PROCEDURES

PROCEDURE

COMPONENT TEST

LETTER

AMAGNETRON ASSEMBLY TEST

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than 1 ohm.

5.To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance the magnetron is grounded and must be replaced.

6.Reconnect all leads removed from components during testing.

7.Reinstall the outer case (cabinet).

8.Reconnect the power supply cord after the outer case is installed.

9.Run the oven and check all functions.

MICROWAVE OUTPUT POWER

The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted).

HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD BE OBSERVED.

Power output of the magnetron can be measured by performing a water temperature rise test. This test should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following components or wiring: silicon rectifier, high voltage capacitor and power transformer. This test will require a 16 ounce (453cc) measuring cup and an accurate mercury thermometer or thermocouple type temperature tester. For accurate results, the following procedure must be followed carefully:

1.Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water with a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through the water until the temperature stabilizes. Record the temperature of the water.

2.Place the cup of water in the oven. Operate oven at 100 PERCENT selecting more than 60 seconds cook time. Allow the water to heat for 60 seconds, measuring with a stop watch, second hand of a watch or the digital read-out countdown.

3.Remove the cup from the oven and again measure the temperature, making sure to stir the thermometer or thermocouple through the water until the maximum temperature is recorded.

4.Subtract the cold water temperature from the hot water temperature. The normal result should be 34.3 to 63.6˚F(19.1 to 35.4˚C) rise in temperature. If the water temperatures are accurately measured and tested for the required time period the test results will indicate if the magnetron tube has low power output (low rise in water temperature) which would extend cooking time or high power output (high rise in water temperature) which would reduce cooking time. Because cooking time can be adjusted to compensate for power output, the magnetron tube assembly should be replaced only if the water temperature rise test indicates a power output well beyond the normal limits. The test is only accurate if the power supply line voltage is 120 volts and the oven cavity is clean.

BPOWER TRANSFORMER TEST

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Disconnect the primary input terminals and measure the resistance of the transformer with an ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be approximately 74.2 ohms; the resistance of the filament coil should be less than 1 ohm.

5.Reconnect all leads removed from components during testing.

6.Reinstall the outer case (cabinet).

7.Reconnect the power supply cord after the outer case is installed.

8.Run the oven and check all functions.

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