SHARP R590BE, R-590BK, R-590BW Service Manual

R-590BK R-590BW

SHARF?

SERVICE MANUAL

S68M116R590BE

MICROWAVE OVEN MODELS

R-590BKlR-590BW

In the interest of user-safety the oven is to be restored to its original condition and only the parts identical to those specified should be used.

WARNING TO SERVICE PERSONNEL: Microwave

ovens contain circuitry capable of producing very high voltage and current. Contact with the following parts may result in a severe, possibly fatal electrical shock.(High Voltage Capacitor,

High Voltage Power Transformer, Magnetron,

High Voltage Rectifier Assembly, High Voltage

Harness etc..)

SECTION

PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICE TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY. Before Servicing Warning to Service Personnel Foreword and Warning

Specifications ...............................................................................

Generallnformation

Key Unit Layout

Operation

Servicing and Troubleshooting Guide TestProcedures TouchControlOutline

Component Replacement and Adjustment Procedure

Microwave Measurement Procedure

Wiring/Schematic Diagram

Parts .....................................................................................

Packing and Accessories

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SHARP ELECTRONICS CORPORATION

PAGE

........... Inside Front Cover

Inside Front Cover

1 2 3 4 5 6 9

11 21 23 32 33 40 45

Service Headquarters: Sharp Plaza, Mahwah, New Jersey, 07430-2135

R-590BK R-590BW

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

( )

Make the following safety checks on all ovens to be serviced before activating the magnetron

(b)

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.

Before turning on microwave power for any service test or inspection within the microwave gen-

( >

erating compartments, check the magnetron, waveguide or transmission line, and cavity for proper alignment, integrity, and connections.

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.

A microwave leakage check to verify compliance with the Federal Performance Standard

( 1

should be performed on each oven prior to releasing the oven to the owner.

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 @

I-800-237-4277.

(RD21101 U)

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 DHHS 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.

(RD81001 U)

SERVICE MANUAL

R-590BK R-590BW

Microwave Ovens R=590BK/R=590BW

Foreword

This manual has been prepared to provide Sharp

Electronics Corporation personnel with complete operation and service information for Sharp microwave oven models R-590BWR-590BW.

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

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

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 are no other visible signs of damage to the

oven.

DANGER

Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing. Service personnel - Do not contact the fol-

/, . .

lowing parts while the appliance is energized;

< .

High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly and High voltage Harness. If provided, Vent Hood, Fan Assembly and Cooling

Fan motor.

Specifications

General Information

Troubleshooting / Test Procedures

Microwave Measurement

All of the parts marked “*” ages more than 25OV.

Removal of the outer case cabinet gives access to volt-

age above 25OV.

All of the parts marked “A” on parts list may cause undue

microwave exposure, by themselves, or when they are

damaged, loosened or removed.

on parts list are used at volt-

Sharp Electronics Corporation

Sharp Plaza

Mahwah, New Jersey 07430-2135

Wiring / Schematic Diagram

R-590BK R-590BW

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 Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc.. Read the Service Manual carefully and follow all instructions.

oltage

Before Servicing

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

2. Open the door and block it open.

3. Discharge the high voltage capacitor.

WARNlNG:RlSK OF ELECTRICAL 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 high volt-

age capacitor (that is the connecting lead of the high voltage rectifier) against the chassis with the use of an insulated screwdriver.

Whenever troubleshooting is performed, the power supply must be disconnected. In some cases it may 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 cabinet.

2 .

Open the door and block it open.

Discharge the high voltage capacitor.

Disconnect the leads to the primary of the power transformer.

Ensure that the leads remain isolated from other

components and oven chassis by using insulation tape.

After the above procedure, reconnect the power supply cord.

When the testing is completed

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

2. Open the door and block it open.

3. Discharge the high voltage capacitor.

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

5. Re-install the outer case cabinet.

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

7. Start the oven and check all functions.

After repairing

1. Reconnect all leads removed from components during testing.

2. Re-install the outer case (cabinet).

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

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

5. Run the oven and check all functions.

Microwave ovens should not be operated 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 to see if the water is hot. If the water remains cold, carry out Before

Servicing procedure and re-examine the connection 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 the microwave leakage test should be carried out.

R-590BK R-590BW

Item

Power Requirements 120 Volts

Power Output

Case Dimensions

Cooking Cavity

1.8 Cu.Ft.

Control Complement

Description

14.0 Amperes 1650 Watts 60 Hertz Single phase, 3 wire grounded

1100 watts (IEC-705 Test Procedure) Operating frequency of 2450 MHz

Width 23.94” Height 13.27” (including feet) Depth 19”

Width 17” Height 9.96”

Depth 17.8”

Tray Size 16” Diameter

Touch Control System Clock (I:00 - 1259) Timer (0 - 99 min. 99 sec.)

Microwave Power for variable cooking

Repetition Rate;

P-HI (HIGH) . . . . . . . . . Full power throughout the cooking time

P-90 . . . , . . . . . . . . . . . . . approx. 90% of full power

P-80 . . . . . . . . . . . . . . . . . approx. 80% of full power

P-70 (MED HIGH) . . . . approx. 70% of full power

P-60 , . . . . . . . . . . . . . . . . approx. 60% of full power

P-50 (MED) . . . . . . . . . . approx. 50% of full power

P-40 . . . . . . . . . . . . . . . . . approx. 40% of full power

P-30 (MED LOW) . . . . .

P-20 . . . . . . . . . . . . . . . . . approx. 20% of full power

P-IO . . . . . . . . . . . . . . . . . approx. 10% of full power

P-O

. . . . . . . . . . . . . . . . . . .

approx. 30% of full power

No power throughout the cooking time

Oven Cavity Light

Safety Standard

FEATURES

Selection button Page turn buttons BOOK MARK button

INDEX button

POPCORN button START/MINUTE button Number button

Yes

UL Listed FCC Authorized

DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J

R-590BK R-590BW

Grounding Instructions

This oven must be fully grounded at all times. This appliance must be connected to a 120 volt, 60 Hz, AC only, 15 Ampere or more 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.

Grounded Receptacle Box

3 Pronged Plug

Grounded Receptacle Box

Grounding Receptacle

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

Where a two-pronged wall-receptacle is encountered, it

is the personal responsibility and obligation of the cus-

tomer to contact a qualified electrician and have it re-

placed with a properly polarized and grounded threepronged wall receptacle or use a grounding adaptor. If an extension cord must be used, it should be a 3-wire,

15 ampere minimum cord.

Oven

Diagram

Grounding Pin

3 Pronged Receptacle

Do not under any

circumstances cut or remove the

Screw

Tab for Grounding Screw

round grounding prong from this plug.

Digital display

2. Auto-Touch control panel

3. Door open button Door latches

5. Removable turntable support Removable turntable

6. Oven lamp

7. Oven door with see through window

8. Waveguide cover

9. Power Cord

10.

Touch Control Panel

During setting “Reminder “, this

mark is displayed

Time of day and date

R-590BK R-590BW

Big LCD display

Reminder mark:

Page turn button: When forward/ Rewind/ Return arrows are displayed on the screen,

you can turn pages by pressing

these buttons

BOOK MARK button

POPCORN button

STOP/CLEAR button

DOOR OPEN button

---I

--I-

POPCORN

MINUTE PLUS

Selection button: When the selection arrow are displayed on the screen, you can select

pressing these buttons.

-.Foreword/Rewind/Return arrows: Foreword arrows-Go to next screen (1 page turn

Rewind arrows-Go back to screen (1 page back)

Return arrows-Go back to screen

INDEX button

START/MINUTE PLUS button

Number buttons

_I---

R-590BK R-590BW

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 moni-

tor switch contacts are opened. When the oven is

plugged in, 120 volts AC is supplied to the control unit (see schematic diagram).

1. The display will show “VIEW VIDEO DEMO“ and

“SET THE CLOCK“.

(For details, see table below.)

Select ” SET THE CLOCK“ referring to the operation

manual. (For details, see table below.)

NOTE: If any buttons are not touched for 30 seconds,

the display will go on to the Video Dimo mode. To cancel the video Demo mode, touch the STOP / CLEAR button and then set the clock.

The display will show the home page after setting the

3. clock.

(For details, see table below.)

4. The following is the example of the home page. in this example the time of the day is set to 4:50 p.m. on

May 23rd.

4:50PM MAY 23

COOK )

REHEAT )

DEFROST b

RESOURCE CENTER b

NOTE: Even if the clock is not set, the display will show

home page by touching the STOP / CLEAR button within 30 seconds after unit is plugged in.

Cooking Condition

Program desired cooking time and Variable Cooking Control by touching the NUMBER pads and the Power Level pad of the Variable Cooking Control. When START is touched, the following operations occur: 1 .

The relay contacts are closed and components connected to the relays (RY-1 and RY-2) are turned on.

(For details, see table below.)

Relay Components

RY-1

1 RY-2

2 .

120 volts AC is supplied to the primary winding of the

power transformer and is converted to approximate-

ly 3.4 volts AC on the filament winding and approximately 2400 volts AC on the high voltage winding.

The filament winding voltage heats the magnetron filament and the high voltage is sent to a voltage dou-

bler circuit.

The microwave energy produced by the magnetron

is channeled through the waveguide into the cavity

Oven Lamp/Turntable Motor/Fan Motor

1 Power Transformer

feed-box and into the cavity where the food is cooked.

5 .

Upon completion of the cooking cycle, the power transformer, oven lamp and cooling fan are turned off and the generation of microwave energy is termi-

nated.

When the door is opened during a cook cycle, the

monitor switch, door sensing switch, secondary interlock switch and primary interlock relay are activated with the following results. The turntable motor, cooling fan motor and the high voltage components

are de-energized. The oven lamp remains on and the digital readout displays the time still remaining in the cook cycle when the door was opened.

The monitor switch is electrically monitoring the op-

eration of the secondary interlock switch and primary

interlock relay and is mechanically associated with the door so that it functions as follows:

When the door opens from a closed position, the

( )

secondary interlock switch and primary interlock relay open their contacts, then the monitor switch contacts close.

When the door is closed from the open position,

(b)

the monitor switch contacts first open and the contacts of the secondary interlock switch close.

If the secondary interlock switch and the primary inter-

lock relay contacts are closed when the door is opened, the monitor switch contacts form a short circuit through the monitor fuse, secondary interlock switch and prima-

ry interlock relay causing the monitor fuse to blow.

Power Level P-O to P-90 Cooking

When Variable Cooking Power is programmed, 120 volts AC 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

(100% power)

(approx.

approx. 60% power)

1 (approx. 50% power) 18 sec.

( (approx. 40% power) 16 sec.

( (approx. 30% power)

( (approx. 20% power)

1 (approx. 10% power)

1 (approx. 0% power) j 0 sec.

90% power)

80% power)

70% power)

On Time

32 sec.

30 sec.

26 sec.

24 sec.

22 sec. IO sec.

/ 12 sec.

8 sec.

6 sec.

The ON/OFF time ratio does not correspond with the

percentage of microwave power, because approximate-

ly 2 seconds are needed for heating the magnetron fila-

ment.

Off Time

0 sec.

2 sec.

6 sec.

8 sec.

14 sec.

16 sec.

( 20 sec.

24 sec.

26 sec.

I32 sec.

~~ I

~ I

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

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

Sensor Cooking Condition

When using the Sensor Cooking function (Sensor Cook-

ing , the foods are 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 the 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 ex-

periment with each food category and is inputted into the

LSI The following is an example of how the AH Sensor Works:

Sensor detects moisture and humidity and calcu-

3. lates cooking time and variable power level.

R-590BK R-590BW

’ s

1. Soup at room temperature Vapor is emitted very slowly.

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

Cooking Sequence

1. Touch REHEAT .

Note: The oven should not be operated in either mode

immediately after plugging in the unit. Wait five minutes before cooking in sensor mode.

2 .

The coil to the shut off relay (RY-1) is energized, the oven lamp, turntable motor and cooling fan motor are turned on and the power transformer remains off.

After about 16 seconds, the cook relay (RY-2) is en-

ergized. The power transformer is turned on, microwave energy is produced and first stage cooking is started.

Note: The 16 second delay is for cooling time required

to remove any vapor from the oven cavity and sensor. During this first stage, do not open the oven door or touch the STOP/CLEAR pad.

When the sensor detects the vapor emitted from the food, the display switches over the remaining cook-

ing time and the timer counts down to zero. At this time, the door may be opened to stir food, turn it or season, etc.

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.

By opening the door or touching the STOP/CLEAR

pad, the time of day will re-appear on the display and

the oven will revert to an OFF condition.

R-590BK R-590BW

DESCRIPTION AND FUNCTION OF COMPONENTS

Cooling Fan Motor

The cooling fan motor drives a blade which draws exter-

nal cool air. This cool air is directed through the air vanes surrounding the magnetron to cool the magnetron. This air is channeled through the oven cavity to re-

move steam and vapors given off from the heating foods. It is then exhausted through exhaust vents in the oven cavity.

Oven Temperature Fuse

The oven temperature fuse located on the top of the

oven cavity is designed to prevent damage to the unit if the foods in the oven catch fire due to over heating pro-

duced by improper setting of cook time or failure of control unit.

Under normal operation, the oven temperature fuse remains closed. However, when abnormally high temperatures are reached within the oven cavity, the fuse will open at 144OC, causing the oven to shut down.

Note: This is a fuse and it does not reset.

Magnetron Temperature Fuse

The magnetron temperature fuse located on top of the

magnetron duct is designed to prevent damage to the

magnetron if an over heated condition develops in the tube due to cooling fan failure, obstructed air ducts, dirty

or blocked air intake, etc.

Under normal operation, the magnetron temperature fuse remains closed. However, when abnormally high temperatures are reached within the magnetron the

fuse will open at 144OC, causing the oven to shut down.

Note: This is a fuse and it does not reset.

Door Open Mechanism

The door is opened by pushing the open button on the

control panel.

When the open button is pushed, the open button

pushes up the switch lever, and then the switch lever

pushes up the latch heads.

The latch heads are moved upward and released from

the latch hook. Now the door will open.

Door Sensing I 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 circuit to all components, except

the oven lamp. 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 the primary interlock relay located on the control panel 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 and secondary interlock switch fail to open when the door is opened.

Monitor Switch Functions

When the door is opened, the monitor switch contacts close (to the ON condition) due to their being

normally closed. At this time the primary interlock relay and secondary interlock switch are in the OFF condition (contacts open) due to their being normally open contacts.

2 .

When the door is closed, the monitor switch contacts are first opened and then the door sensing switch and the secondary interlock switch contacts close.

Note: When opening the door, each of these

switches operate inversely.

3 .

If the door is opened and the primary interlock relay

and secondary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing

of the monitor switch contacts.

Before replacing a blown monitor fuse, test the primary interlock relay, door sensing switch, monitor switch 1 and secondary interlock switch for proper operation. (Refer to section “Test Procedures”.)

Door Sensing

, Switch

Fuse Block

Latch Heads

Secondary

Interlock

Switch

NOTE:

MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY.

R-590BK R-590BW

SERVICING

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.

Before replacing a blown monitor fuse, test the door sensing switch, primary interlock relay, secondary interlock switch and monitor switch for proper operation. (Refer to “Test Procedure” section.)

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

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

2. Open the door and block it open.

3. Discharge the 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 insulated tape.

6. After the above procedure install the outer case cabinet and 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 the high voltage capacitor.

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

5. Re-install the outer case (cabinet).

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

7. Run the oven and check all functions.

Troubleshooting Guide

Off Condition

Problem

Home fuse blows when power cord is plugged into the wall receptacle.

Monitor fuse blows when power is applied.

Display does not illuminate when Shorted or open wiring power cord is plugged in.

Display does not operate properly Primary interlock relay or door sens- Procedure E when STOP/CLEAR button is ing switch touched.

Oven lamp does not light with door Shorted or open wiring opened.

Shorted power cord or wire harness

Shorted power cord or wire harness Secondary interlock or monitor

switch

Monitor switch or monitor fuse Oven temperature fuse Control unit

Control unit Key unit unit

Monitor fuse Oven temperature fuse Oven lamp or socket Control unit

Relay (RYI)

Possible Cause

Check or replace

Procedure E

Check or replace

Procedure E Procedure F Procedure G

Procedure G Procedure K Check or replace

Procedure E Procedure F

Check or replace

Procedure G Procedure H

Test Procedure

R-590BK R-590BW

Problem

3ven lamp does not light at all.

[>ven lamp lights, but fan motor and turntable motor do not operate.

Dven does not go into cook cycle Nhen START button is touched.

&en seems to be operating but little or no heat is produced in oven road. (incompletely cooked or not zooked at all at the end of cook cycle.)

Oven goes into a cook cycle but extremely uneven heating is produced in oven load (food).

Oven does not cook properly when programmed for Cooking Power

P-50 (MED.) mode. (Operates

properly on Cooking Power P-HI

(HIGH) mode.)

Oven goes into COMPU DEFROST but food is not defrosted well

The oven is in the sensor cooking condition but AH sensor does not end or AH sensor turns off about a maxi-

mum of 30 minutes after start. When a cup of water is heated by sensor, the oven does not shut off when the water is boiling.

Troubleshooting Guide

Cook Condition Possible Cause

Shorted or open wiring Oven lamp or socket Control unit Shorted or open wiring Cooling fan motor Turntable motor Shorted or open wiring Primary interlock system Monitor fuse Magnetron or oven temperature

fuse Relay (RYl) Shorted or open wiring

Magnetron Power transformer Rectifier assembly H.V. capacitor Primary interlock system Shorted or open wiring Turntable motor Low voltage Dirty oven cavity Wrong operation Shorted or open wiring

Control unit

Magnetron Wrong operation 1 Check Low voltage Check

Dirty oven check Check Compu Defrost Procedure J Control Unit Procedure G

AH Sensor

Check or replace Check or replace Procedure G

/ Check or replace

Check or replace Check or replace Check or replace Procedure E Procedure E Procedure F

Procedure H Check or replace Procedure A Procedure B

j Procedure C

Procedure D Procedure E

Check or replace 1 Check or replace 1 Check 1 Check

Check

Check or replace

Procedure G

Procedure A

Procedure L

Test Procedure

TEST PROCEDURES

R-590BK R-590BW

Procedure Letter

Magnetron Assembly Test

1. Disconnect the power supply cord, and then remove outercase cabinet.

2. Open the door and block it open.

3. Discharge the 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 1Q.

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 (shorted) and must be replaced.

6. Reconnect all leads removed from components during testing.

7. Re-install the outercase cabinet.

8. Reconnect the power supply cord after installing the outer case cabinet.

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 assembeled

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: high voltage rectifier, high voltage capacitor and power transformer. This test will require a 16 oz. (453~~) measuring cup and an accurate mercury thermometer or thermocouple type temperature tester. For accurate results, the following procedure must be fol-

lowed:

1 .

2 .

Component Test

Fill the measuring cup with 16 oz. (453~~) 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. Place the cup of water in the oven. Operate oven on HIGH selecting 62 seconds cook time. Allow the water to heat. 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. Subtract the cold water temperature from the hot water temperature. The normal result should be 38Oto 78OF (21 O to 42.6OC) rise in temperature. If the water temperatures are accurately measured and are 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 cook 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.

B. Power Transformer

1 .

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

2 .

Open the door and block it open.

Discharge the high voltage capacitor.

3 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 &I and the resistance of the high voltage coil should be approximately 1OOQ; the resistance of the filament coil should be less than IQ.

Reconnect all leads removed from components during testing.

Re-install the outercase cabinet.

7 .

Reconnect the power supply cord after installing the outer case cabinet.

8 .

Run the oven and check all functions.

Note: High voltages are present at the high voltage terminal, so do not attempt to measure the fila-

ment and high voltage.

R-590BK R-590BW

Procedure Letter

c. High Voltage Rectifier Test

1 .

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

2 .

Open the door and block it open.

Discharge the high voltage capacitor.

4 .

Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance across the terminals and observe, reverse the leads to the rectifier terminals and observe meter reading. If a short is indicated in both directions, or if an infinite resistance is read in both directions, the rectifier is probably defective and should be replaced.

5 .

Reconnect all leads removed from components during testing.

Re-install the outer case cabinet.

7 .

Reconnect the power supply cord after installing the outer case cabinet.

8 .

Run the oven and check all functions.

Note: Be sure to use an Ohm-Meter that will supply a forward bias voltage of more than 6.30 Volts.

High Voltage Capacitor Test

(Discharge the high voltage capacitor before touching any oven components or wiring.)

1. Disconnect the power supply cord, and then remove outercase.

2. Open the door and block it open,

3. Discharge the high voltage capacitor. 4 If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads

and check for short or open between the terminal using an ohmmeter. Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate continuity initially and once the capacitor is charged an open circuit.

If the above is not the case, check the capacitor with an ohmmeter to see if it is shorted between

each terminal and case. If it is shorted, replace the capacitor.

5. Reconnect all leads removed from components during testing.

6. Re-install the outercase (cabinet).

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

8. Run the oven and check all functions.

Component Test

Secondary Interlock Switch Test

1. Disconnect the power supply cord, and then remove outercase.

2. Open the door and block it open.

3. Discharge the high voltage capacitor. 4 Isolate the switch and connect the ohmmeter to the common (COM) and normally open (NO) termi-

nal of the switch. The meter should indicate an open circuit with the door open and a closed circuit

with the door closed. If improper operation is indicated, replace the secondary interlock switch.

5. Reconnect all leads removed from components during testing.

6. Re-install the outercase (cabinet).

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

8. Run the oven and check all functions.

Primary Interlock System Test

Door Sensing Switch

1. Disconnect the power supply cord, and then remove outercase.

2. Open the door and block it open.

3. Discharge the high voltage capacitor.

4. Isolate the switch and connect the ohmmeter to the common (COM) and normally open (NO) termi-

nal of the switch. The meter should indicate an open circuit with the door open and a closed circuit

with the door closed. If improper operation is indicated, replace the door sensing switch.

5. Reconnect all leads removed from components during testing.

6. Re-install the outercase (cabinet).

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

8. Run the oven and check all functions.

TEST PROCEDURES

R-590BK R-590BW

Procedure Letter

-. ,

. :

Component Test

Continued

Primary Interlock Relay (RY-2)

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

Open the door and block it open.

Discharge the high voltage capacitor.

4 .

Disconnect two (2) wire leads from the relay on the printed circuit board in the control panel assembly. The relay is located on the bottom portion of the circuit board on the backside of the control panel assembly. Connect an ohmmeter to the male terminals and observe the meter reading. The relay contacts should be open. If the relay contacts are closed, replace the primary interlock relay or the circuit board.

Reconnect all leads removed from components during testing.

6. Re-install the outer case cabinet.

7. Reconnect the power supply cord after installing the outer case cabinet.

8. Run the oven and check all functions.

Monitor Switch Test

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

2. Open the door and block it open.

3. Discharge the high voltage capacitor. 4 Disconnect the oven from the power supply.

Before performing this test, make sure that the secondary interlock switch and primary interlock relay are operating properly referring to the above Switch Test Procedure. Disconnect the wire lead from the monitor switch (NC) terminal. Check the monitor switch operation by using the ohmmeter as follows: When the door is open, the meter should indicate a closed circuit. With the door open, take a screw driver and push in the monitor switch actuator located through the lower latch hole on the faceplate of the cavity. The meter should indicate a open circuit. If improper operation is indicated, the monitor switch may be defective and should be replaced. After testing the monitor switch, re-connect the wire lead to the monitor switch (NC) terminal and check continuity of the monitor circuit.

5. Reconnect all leads removed from components during testing.

6. Re-install the outer case cabinet.

7. Reconnect the power supply cord after installing the outer case cabinet.

8. Run the oven and check all functions.

WhiteWires Connected to Common Terminal

Monitor Switch

+ 33 hidden pages

SHARP R590BE, R-590BK, R-590BW Service Manual

TABLE OF CONTENTS

WARNING TO SERVICE PERSONNEL

Before Servicing

When the testing is completed

After repairing

Grounding Instructions

Touch Control Panel

OPERATION

Description of Operating Sequence

Off Condition

Cooking Condition

Sensor Cooking Condition

Cooking Sequence

DESCRIPTION AND FUNCTION OF COMPONENTS

Cooling Fan Motor

Oven Temperature Fuse

Magnetron Temperature Fuse

Door Open Mechanism

Monitor Switch

Monitor Switch Functions

Troubleshooting Guide

Off Condition

TEST PROCEDURES

B. Power Transformer

c. High Voltage Rectifier Test

Primary Interlock System Test

Monitor Switch Test