SHARP R540DU, R-540DK, R-540DW Service Manual
SERVICE MANUAL
S5010R540DUW/
MICROWAVE OVEN
R-540DK
R-540DW
12 : 30 PM
123
456
78
Minute
0
Plus +
.
TOUCH
SCREEN
MINUTE
STOP
PLUS
CLEAR
ONE TOUCH SENSOR
Reheat Popcorn
6x6 NO GUESS COOKING
6 Categories + 36 Foods
Vegetables Meat Poultry
Fish/
Frozen
Seafood
Food
More From Your Microwave
6 x 6
Beverage
Defrost
Center
3 + 6
MODELS
9
Kitchen
Timer
START
Baked
Potatoes
Pasta
Grains
Set Up
In the interest of user-safety the oven should be restored to its original
R-540DK
R -540DW
condition and only 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..)
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 ................................................................29
PICTORIAL DIAGRAM ........................................................................................................................................35
POWER UNIT CIRCUIT ......................................................................................................................................36
LSI UNIT CIRCUIT...............................................................................................................................................37
PRINTED WIRING BOARD .................................................................................................................................40
PARTS LIST ........................................................................................................................................................41
PACKING AND ACCESSORIES .........................................................................................................................43
SHARP CORPORATION
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-540DK
R-540DW
PRECAUTIONS TO BE OBSER VED BEFORE AND
DURING SER VICING TO A VOID POSSIBLE
EXPOSURE TO EXCESSIVE MICROW A VE
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.
W ARNING TO SER VICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with
following parts
fatal, electrical shock.
(Example)
High Voltage Capacitor, High Voltage Power Trans-
former, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
may result in a severe, possibly
Don't Touch !
Danger High Voltage
R-540DK
R-540DW
Before Servicing
1. Disconnect the power supply cord ¬, 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.
1
R-540DK
R-540DW
MICROW A VE 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.
2
SERVICE MANUAL
R-540DK
R-540DW
MICROWAVE OVEN
R-540DK/R-540DW
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the
SHARP MICROWAVE OVEN, R-540DK, R-540DW.
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.
PRODUCT DESCRIPTION
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST
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
3
R-540DK
R-540DW
SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts / 13.8 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output 1200 watts (IEC TEST PROCEDURE)
Operating frequency of 2450MHz
Case Dimensions Width 24"
Height 13-3/8"
Depth 19-1/8"
Cooking Cavity Dimensions Width 17-1/2"
Height 10-1/2"
2.0 Cubic Feet Depth 18-5/8"
Control Complement Touch Control System
Clock ( 1:00 - 12:59 )
Timer (0 - 99 min. 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
POWER 100% ................................Full power throughout the cooking time
POWER 90% ................................................... approx. 90% of Full Power
POWER 80% ................................................... approx. 80% of Full Power
POWER 70% ................................................... approx. 70% of Full Power
POWER 60% ................................................... approx. 60% of Full Power
POWER 50% ................................................... approx. 50% of Full Power
POWER 40% ................................................... approx. 40% of Full Power
POWER 30% ................................................... approx. 30% of Full Power
POWER 20% ................................................... approx. 20% of Full Power
POWER 10% ................................................... approx. 10% of Full Power
POWER 0% ................................. No power throughout the cooking time
TOUCH SCREE N, MINUTE PLUS pad, STOP/CLEAR pad
START pad, ONE TOUCH SENSOR pads
6 X 6 NO GUESS COOKING pads
More From Your Microwave pad
Beverage Center pad, Defrost pad, Set Up 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
contact a qualified electrician and have it replaced with a properly grounded three-pronged wall receptacle or have a
4
grounding adapter properly grounded and polarized. If the extension
3-Pronged
Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
cord must be used, it 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-
MOVE THE ROUND GROUNDING PRONG FROM THIS
PLUG.
OVEN DIAGRAM
1. One touch door open button.
Push to open door.
2. Door latches.
The oven will not operate unless the
door is securely closed.
3. Removable turntable support.
4. Removable turntable.
The turntable will rotate clockwise or
counterclockwise.
5. Oven lamp.
It will light when oven is operating or
door is opened.
6. Oven door with see-through window.
7. Ventilation openings. (Rear)
8. Auto-Touch control panel.
9. Touch screen.
10.Coupling.
11.Wave guide cover.
12.Power supply cord
TOUCH CONTROL PANEL
6
2
10
3
R-540DK
R-540DW
5
11
4
7
12
9
8
1
See note
12 : 30 PM
123
456
7809
STOP
Kitchen
Timer
START
Minute
Plus +
TOUCH . SCREEN
MINUTE
PLUS
CLEAR
ONE TOUCH SENSOR
Reheat Popcorn
6x6 NO GUESS COOKING
6 Categories + 36 Foods
Vegetables Meat Poultry
Fish/
Seafood
More From Your Microwave
Frozen
Food
Baked
Potatoes
Pasta
Grains
6 x 6
Beverage
Center
Defrost
3 + 6
Set Up
NOTE:
The directed features are disabled after
three minutes 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.
5
R-540DK
R-540DW
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). Page 8
1. "Set clock" key and "Video demo" key will be appeared
on the touch screen.
2. Touch "Set clock" key and set the clock referring to the
operation manual.
NOTE: If any keys are not touched for 30 seconds, the
touch screen will go on to the Video Demo mode. To
cancel the Video Demo mode, touch the STOP/
CLEAR pad. And then set the clock.
3. The touch screen will show the home page after setting
the clock.
4. The following is the example of the Home page in the
case the time of the day is set to 12:30 p.m..
12 : 30 PM
123
456
7809
Minute
Plus +
Kitchen
Timer
NOTE: Even if the clock is not set, the display will show the
Home page by touching the STOP/CLEAR pad
within 30 seconds after plugged in.
COOKING CONDITION
Program desired cooking time by touching the NUMBER
keys on the touch screen. Program the power level by
touching the POWER LEVEL key and then touch the
desired percentage key on the touch screen.
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), Page 8
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 3.3 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% TO 90% 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
POWER 100% (100% power) 32 sec. 0 sec.
POWER 90% (approx. 90% power) 30 sec. 2 sec.
POWER 80% (approx. 80% power) 26 sec. 6 sec.
POWER 70% (approx. 70% power) 24 sec. 8 sec.
POWER 60% (approx. 60% power) 22 sec. 10 sec.
POWER 50% (approx. 50% power) 18 sec. 14 sec.
POWER 40% (approx. 40% power) 16 sec. 16 sec.
POWER 30% (approx. 30% power) 12 sec. 20 sec.
POWER 20% (approx. 20% power) 8 sec. 24 sec.
POWER 10% (approx. 10% power) 6 sec. 26 sec.
POWER 0% (approx. 0% power) 0 sec. 32 sec.
6
R-540DK
R-540DW
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 cooking function (See sensor cooking
menus), 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
input into the LSI.
An example of how sensor works: (BAKED POTATOES)
1. Potatoes at room temperature. Vapor is emitted very
slowly.
MICROWAVE
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.
The followings are the sensor cooking menus.
Reheat
Popcorn
Baked potatoes
Vegetables
Ground beef or Meat
Boneless Chicken Breast, Bone-in Chicken Pieces and
Ground Poultry or Poultry
Fish / Seafood
Vegetables, Entrees, Main Dishes and Snacks of Frozen
food
White Rice and Brown Rice of Pasta Grains
Frozen breakfast food, Meal in cup, Hot dogs in buns,
Soup, Frozen sandwich, Stuffed Acorn Squash,
Ratatouille of More from Your Microwave
2. Heat Potatoes. 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 One Touch Sensor pads (in case of one
touch sensor).
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.
7
R-540DK
R-540DW
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
NOTE: Indicates components with potential above 250 V.
120V AC
60 Hz
MAGNETRON
TEMP.
FUSE
GRN
CAVITY
TEMP.
FUSE
MONITOR
FUSE 20A
A2
A1
CONTROL UNIT
OL FM
OVEN
LAMP
SECONDARY
INTERLOCK
SWITCH
(RY-1)
TTM
TURNTABLE
MOTOR
COM.
FAN
MOTOR
N.O.
COM.N.O.
B1 B2
(RY-2)
PRIMARY
INTERLOCK
RELAY
DOOR
SENSING
SWITCH
F3
F2
AH SENSOR
F1
N.C.
MONITOR
SWITCH
COM.
Figure O-1. Oven Schematic-Off Condition
CAPACITOR 1.0µF
AC 2300V
POWER
TRANSFORMER
H.V. RECTIFIER
MAGNETRON
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. COOKING TIME PROGRAMMED.
3. VARIABLE COOKING CONTROL "POWER 100 %
PROGRAMMED".
4. "START" PAD TOUCHED.
120V AC
60 Hz
MAGNETRON
TEMP.
FUSE
GRN
CAVITY
TEMP.
FUSE
MONITOR
FUSE 20A
A2
A1
CONTROL UNIT
OL FM
OVEN
LAMP
SECONDARY
INTERLOCK
SWITCH
(RY-1)
TTM
TURNTABLE
MOTOR
COM.
FAN
MOTOR
N.O.
COM.N.O.
B1 B2
(RY-2)
PRIMARY
INTERLOCK
RELAY
DOOR
SENSING
SWITCH
F3
F2
F1
N.C.
MONITOR
SWITCH
COM.
CAPACITOR 1.0µF
AC 2300V
POWER
TRANSFORMER
H.V. RECTIFIER
MAGNETRON
Figure O-2. Oven Schematic-Cooking Condition
8
DESCRIPTION AND FUNCTION OF COMPONENTS
R-540DK
R-540DW
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to the Figure D-1. When the open button
is pushed, the open button pushes up the switch lever, and
then the switch lever pushes up the latch head. The latch
heads are moved upward and released from latch hook.
Now the door will open.
Latch Heads
Door
Switch Lever
Door Sensing
Switch
Monitor Switch
Secondary Interlock
Switch
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the lower
position of the latch hook. 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.
open, the monitor fuse blows simultaneously with closing
of the monitor switch contacts.
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
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 of the food. 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.
CAVITY TEMPERATURE FUSE
The cavity temperature fuse 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 cavity temperature fuse will open.
Under normal operation, the cavity temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the cavity temperature fuse will
open at 302˚F(150˚C) causing the oven to shut down.
NOTE: This is a fuse. It does not reset.
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
MAGNETRON TEMPERATURE FUSE
The magnetron temperature fuse 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 magnetron temperature fuse
remains closed. However, when abnormally high temperatures are reached within the magnetron, the magnetron
temperature fuse will open at 302˚F(150˚C) causing the oven
to shut down.
NOTE: This is a fuse. It does not reset.
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R-540DK
R-540DW
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 FFS-BA016/
KIT 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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R-540DK
R-540DW
CK = Check / RE = Replace
CONDITION
OFF
CONDITION
COOKING
CONDITION
SENSOR
COOKING
CONDITION
TEST PROCEDURE
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
PROBLEM
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.
All letters and indicators do not appear in
display when power cord is first plugged
into wall outlet.
Touch screen does not operate properly
when STOP/CLEAR key is touched.
(Buzzer should sound and Home Page
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.)
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 50%
mode. (Operates properly on cooking
POWER 100 % mode.)
Oven goes into COMPU DEFROST but
food is not defrosted well.
AH sensor does not end during Sensor
cooking condition. (Oven does not shut
off after a cup of water is boiling by
sensor cooking.)
Oven stops at 16 sec. after starting.
RE RE ABCDEEFFGHRE RE CK I CK CK CK JKLMN
SHORT IN POWER CORD
SHORT OR OPENED WIRING
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
CAVITY TEMPERATURE FUSE
MAGNETRON TEMPERATURE FUSE
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
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R-540DK
R-540DW
TEST PROCEDURES
PROCEDURE
LETTER
A MAGNETRON 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:
COMPONENT TEST
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 POWER 100% 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 33
to 62˚F(18.6 to 34.5˚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.
B POWER 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 80 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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