R-408CW
R-409CK
SHARP@
R-408CW
SERVICE MANUAL
S39M125R408CE
MICROWAVE OVEN MODELS
R-408CW/R=409CK
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..)
TABLE OF CONTENTS
SECTION
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICE TO
AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY.
Before Servicing .............................................................
Forewordandwarning
Warning to Service Personnel
Specifications ...............................................................................
Generalinformation
KeyUnitLayout
Operation ..................................................................................
Servicing and Troubleshooting Guide
TestProcedures..........................................................................~
Touch Control Outline
Component Replacement and Adjustment Procedure
Microwave Measurement Procedure
Wiring/Schematic Diagram
Parts .....................................................................................
Packing and Accessories
.......................................................................
.................................................................
.........................................................................
.............................................................................
..........................................................
.......................................................................
...........................................
..........................................................
..................................................................
....................................................................
SHARP ELECTRONICS CORPORATION
Service Headquarters: Sharp Plaza, Mahwah, New Jersey, 07430-2135
...........
PAGE
Inside Front Cover
Inside Front Cover
1
2
3
4
5
6
8
. 10
18
23
29
30
35
39
Do not operate or allow the oven to be operated with the door open.
a
( )
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.
C
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
(d)
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 releasing oven to the owner.
(RD21101U)
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.
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
SHARR
Microwave Ovens
R=408CW/R=409CK
Foreword
This manual has been prepared to provide Sharp
Electronics Corporation personnel with complete
operation and service information for Sharp microwave
oven models R-408CW/R-409CK.
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 following 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.
All of the parts marked “*” on parts list are used at voltages more than 25OV.
Removal of the outer case cabinet gives access to voltage above 250V.
All of the parts marked “A” on parts list may cause undue
microwave exposure, by themselves, or when they are
damaged, loosened or removed.
Specifications
General Information
Key Unit Layout
Operation
Troubleshooting /
Test Procedure&
Touch Control Panel
and hdjustmeni
Wiring / Schematic Diagram
Sharp Electronics Corporation
Sharp Plaza
Mahwah, New Jersey 07430-2135
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.
Before Servicing
Don’t Touch !
Danger High Vol
tage
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.
WARNING: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 voltage 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.
. 3.
Discharge the high voltage capacitor.
Disconnect the leads to the primary of the power
4.
transformer.
Ensure that the leads remain isolated from other
5.
components and oven chassis by using insulation
tape.
After the above procedure, reconnect the power sup-
6.
ply 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 dur-
ing 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 car-
ried out.
SPECIFICATIONS
Item Description
Power Requirements 120 Volts
13.3 Amperes
1550Watts
60 Hertz
Single phase, 3 wire grounded
Power Output 1100 watts (IEC-705 Test Procedure)
Operating frequency of 2450 MHz
Case Dimensions Width 2111/,$
Height 123/<’ (including feet)
Depth 173/i’
R-408CW
R-409CK
Cooking Cavity
1.4 Cu.Ft.
Control Complement Touch Control System
Width 15”
Height 97/,;’
Depth 1631:’
Tray Size 141/< Diameter
Clock (I:00 - 12:59)
Timer (0 - 99 min. 99 sec.)
Microwave Power for variable cooking
Repetition Rate;
P-HI (HIGH) . . . . . . . . .
P-90 . . , . . . . . . . . . . . . . . approx. 90% of full power
P-80 . . . . . . . . . . . . . . . . .
P-70 (MED HIGH) . . . .
P-60 . . . . . . . . . . . . . . . . .
P-50 (MED) . . . . . . . . . .
P-40 . . . . . . . . . . . . . . . . .
P-30 (MED LOW) . . . . .
P-20 . . . . . . . . . . . . . . . . .
P-IO . . . . . . . . . . . . . . . . .
P-O...................
FEATURES
Instant Action
Compu Defrost(3)
Minute Plus
Timer/Clock
Popcorn
Variable Power (10)
4 Stage Cooking
Full power throughout the cooking time
approx. 80% of full power
approx. 70% of full power
approx. 60% of full power
approx. 50% of full power
approx. 40% of full power
approx. 30% of full power
approx. 20% of full power
approx. 10% of full power
No power throughout the cooking time
Oven Cavity Light
Safety Standard
Yes
UL Listed
FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
3
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.
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 customer to contact a qualified electrician and have it replaced 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.
Grounded
Grounded
Receptacle Box
3 Pronged Plug
Grounding Pin
\
Receptacle
3 Pronged Receptacle
Receptacle Box
Grounding Screw
Do not under any circumstances cut or remove the
round grounding prong from this plug.
Oven
Diagram
1. Digital display
2. Auto-Touch control panel
3. Door open button
4. Door latches
5. Removable turntable support
6. Removable turntable
7. Oven lamp
8. Oven door with see through window
9. Waveguide cover
10. Power Cord
4
Key Unit Layout
MINUTE PLUS
INSTANT ACTION
TO ADJUST QUANTITY -TOUCH PAD AGAIN
1 Ground Meat
2 Steaks/Chops
3 Chicken Pieces
I
1
1
4
1
7
/
Power
Level
R-408CW
COMPU DEFROST
* I
5 1
8
1 Timer
0
3
6
9
Clock
3 Chicken Pieces
f11213’
I
I
t
I
I I
I
I 5 I 6
4
I I
I
stop
Clear
( START j
R-409CK
I
I
R-408CW
R-409CK
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 the oven is
plugged in, 120 volts AC is supplied to the control unit
(see schematic diagram). The display flashes 88:88. To
set any program or set the clock, first touch the STOP/
CLEAR pad. The display clears and “ : ” appears and the
control unit counts every minute.
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
RY-1 Oven Lamp/Turntable Motor/Fan Motor
RY-2
120 volts AC is supplied to the primary winding of the
2.
power transformer and is converted to approximately 3.3 volts AC on the filament winding and approximately 2370 volts AC on the high voltage winding.
The filament winding voltage heats the magnetron
3.
filament and the high voltage is sent to a voltage doubler circuit.
4.
The microwave energy produced by the magnetron
is channeled through the waveguide into the cavity
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 terminated.
When the door is opened during a cook cycle, the
6.
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-
7.
eration of the secondary interlock switch and primary
Components
Power Transformer
OPERATION
interlock relay and is mechanically associated with
the door so that it functions as follows:
a.
( )
m
(b)
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 oper-
ated by the control unit within a 32 second time base. Mi-
crowave power operation is as follows:
1 Vari-Mode 1 On Time
P - HI (HIGH)
(100% power) 32 sec.
P - 90
(approx. 90% power) 30 sec.
P - 80
(approx. 80% power)
P - 70 (MED, HIGH)
(approx. 70% power) 24 sec.
P - 60
(approx. 60% power)
P - 50 (MED)
(approx. 50% power) 18 sec.
P - 40
(approx. 40% power) 16 sec.
P - 30 (MED, LOW)
(approx. 30 % power)
P - 20
(approx. 20% power)
P-IO
(approx. 10% power)
P-O
(0% power)
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.
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,
the monitor switch contacts first open and the
contacts of the secondary interlock switch close.
IOff Time 1
0 sec.
2 sec.
26 sec. 6 sec.
8 sec.
22 sec.
12 sec.
8 sec.
6 sec.
0 sec.
IO sec.
14 sec.
16 sec.
sec.
20
24 sec.
26 sec.
32 sec.
6
DESCRIPTION AND FUNCTION OF COMPONENTS
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 to cool the magnetron. This air is channeled through the oven cavity to remove 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 produced by improper setting of cook time or failure of control unit.
Under normal operation, the oven temperature fuse re-
mains closed. However, when abnormally high temperatures are reached within the oven cavity, the fuse will
open at 150°C, 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 1 50°C, causing the oven to shut down.
Note: This is a fuse and it does not reset.
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.
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.
If the door is opened and the primary interlock relay
and secondary interlock switch contacts fail to open,
the monitor fuse blows simultaneously
of the monitor switch contacts.
Before replacing a blown monitor fuse, test the primary interlock relay, door sensing switch, monitor switch
and secondary interlock switch for proper operation.
(Refer to section “Test Procedures”.)
with closing
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 / 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 lo-
cated on the control panel circuit board.
/ Switch
NOTE: MONITOR FUSE AND MONITOR SWITCH
ARE REPLACED AS AN ASSEMBLY.
Monitor
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.
tion.)
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.
(Refer to “Test Procedure” sec-
Troubleshooting Guide
Off Condition
Problem Possible Cause Test Procedure
Home fuse blows when power cord is Shorted power cord or wire harness
plugged into the wall receptacle.
Monitor fuse blows when power is ap- Shorted power cord or wire harness
plied.
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.
Secondary interlock or monitor Procedure E
switch
Monitor switch or monitor fuse
Oven temperature fuse
Control unit Procedure G
Control unit
Key unit unit
Monitor fuse
1 Oven temperature fuse 1 Procedure F
Oven lamp or socket
Control unit
Relay (RYI)
Check or replace
Check or replace
Check or replace
Procedure E
Procedure F
Procedure G
Procedure K
Check or replace
Procedure E
Check or replace
Procedure G
Procedure H
8
Problem
mamp does not light at all.
Oven lamp lights, but fan motor and
turntable motor do not operate.
Oven does not go into cook cycle
when START button is touched.
Oven seems to be operating but
little or no heat is produced in oven
load. (incompletely cooked or not
cooked at all at the end of cook
cycle.)
Oven goes into a cook cycle but extremely uneven heating is produced
in oven load (food).
-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
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 Procedure A
Wrong operation
Low voltage
Dirty oven check Check
Compu Defrost
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
Procedure C
Procedure D
Procedure E
Check or replace
Check or replace
Check
Check
Check
Check or replace
Procedure G
Check
Check
Procedure J
Test Procedure
TEST PROCEDURES
Procedure Letter
A .
. Power Transformer
B
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 IQ.
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:
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.
through the water until the temperature stabilizes.
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 38” to 78°F (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.
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 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 Q and the resistance of the high voltage coil should be approximately 900; the resistance of the filament coil should be less than IQ.
5. Reconnect all leads removed from components during testing.
6. 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.
Component Test
Stir the thermometer or thermocouple
Record the temperature of the water.
10
TEST PROCEDURES
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.
3. 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.
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.
Component Test
Note: Be sure to use an Ohm-Meter that will supply a forward bias voltage of more than 6.30 Volts.
D . 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.
. Secondary Interlock Switch Test
E
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.
11
TEST PROCEDURES
Procedure Letter
. Continued
E
Primary Interlock Relay (RY-2)
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 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.
or the circuit board.
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.
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, reconnect 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.
Component Test
If the relay contacts are closed, replace the primary interlock relay
Red Wire
Connected to
Normally Closed Terminal
Notel: Connect ohmmeter
Note2: Use screwdriver to engage
monitor switch actuator.
Common Terminal
12
Loading...