Sharp R930cs Service Manual

							9
R-930CS
Figure O-2. Oven Schematic-Microwave Cooking Condition
SCHEMATIC
1. DOOR CLOSED.
2. COOKING TIME PROGRAMMED.
3. ÒSTARTÓ PAD TOUCHED.
Figure O-1. Oven Schematic-OFF Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
SCHEMATIC DIAGRAM
IMPORTANT:
During sensor cooking operation, the fire sensing op-
eration sequence will not begin until the AH sensor hasdetected vapors and initiated a sensor cooking cycle.
This is because the operation of the convection fan
would interfere with the AH sensors vapor detection.
CONV.
THERMAL
CUT-OUT
MONITOR SWITCH OVEN LAMP
FAN MOTOR
A-5 A-3
A-1
E-6 CONTROL UNIT
DAMPER
SWITCH THER-
MISTOR DOOR
SENSING
SWITCH
AH SENSOR
DAMPER MOTOR CONVECTION MOTORTURNTABLE MOTOR
HEATIMG ELEMENT
MAGNETRON
POWER 
TRANSFORMER
H.V. RECTIFIER
CAPACITOR
0.94µ
RY4RY5
RY6
RY1
SECONDARY
INTERLOCK
SWITCH
120V
60Hz
TTMFM
COM.
(RY1)
E-5 E-4 E-3E-2 E-1F-3 F-2 F-1
RY3RY2
PRIMARY 
INTERLOCK
RELAY
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
A-9 A-7
CMDMOL
MAGNETRON 
TEMPERATURE
FUSE
FUSE
RY2
CONV.
THERMAL
CUT-OUT
MONITOR SWITCH OVEN LAMP
FAN MOTOR
A-5 A-3
A-1
E-6 CONTROL UNIT
DAMPER
SWITCH THER-
MISTOR DOOR
SENSING
SWITCH
AH SENSOR
DAMPER MOTOR CONVECTION MOTORTURNTABLE MOTOR
HEATIMG ELEMENT
MAGNETRON
POWER 
TRANSFORMER
H.V. RECTIFIER
CAPACITOR
0.94µ
RY4RY5
RY6
RY1
SECONDARY
INTERLOCK
SWITCH
120V
60Hz
TTMFM
COM.
(RY1)
E-5 E-4 E-3E-2 E-1F-3 F-2 F-1
RY3RY2
PRIMARY 
INTERLOCK
RELAY
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
A-9 A-7
CMDMOL
MAGNETRON 
TEMPERATURE
FUSE
FUSE
RY2 
						

							10
R-930CS
DESCRIPTION AND FUNCTION OF COMPONENTS
SCHEMATIC
1. DOOR CLOSED.
2. CONVECTION PAD TOUCHED.
3. DESIRED TEMP. TOUCHED.
4. COOKING TIME PROGRAMMED.
5. ÒSTARTÓ PAD TOUCHED.
SCHEMATIC
1. DOOR CLOSED.
2. MIX COOKING PAD TOUCHED.
3. COOKING TIME PROGRAMMED.
4. ÒSTARTÓ PAD TOUCHED.
5. RY2 AND RY3 WILL ALTERNATELY CLOSE.
DURING COOK CYCLE.
Figure O-4. Oven Schematic-Convection Cooking Condition Figure O-3. Oven Schematic-Automatic Mix Cooking Condition
CONV.
THERMAL
CUT-OUT
MONITOR SWITCH OVEN LAMP
FAN MOTOR
A-5 A-3
A-1
E-6 CONTROL UNIT
DAMPER
SWITCH THER-
MISTOR DOOR
SENSING
SWITCH
AH SENSOR
DAMPER MOTOR CONVECTION MOTORTURNTABLE MOTOR
HEATIMG ELEMENT
MAGNETRON
POWER 
TRANSFORMER
H.V. RECTIFIER
CAPACITOR
0.94µ
RY4RY5
RY6
RY1
SECONDARY
INTERLOCK
SWITCH
120V
60Hz
TTMFM
COM.
(RY1)
E-5 E-4 E-3E-2 E-1F-3 F-2 F-1
RY3RY2
PRIMARY 
INTERLOCK
RELAY
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
A-9 A-7
CMDMOL
MAGNETRON 
TEMPERATURE
FUSE
FUSE
RY2
CONV.
THERMAL
CUT-OUT
MONITOR SWITCH OVEN LAMP
FAN MOTOR
A-5 A-3
A-1
E-6 CONTROL UNIT
DAMPER
SWITCH THER-
MISTOR DOOR
SENSING
SWITCH
AH SENSOR
DAMPER MOTOR CONVECTION MOTORTURNTABLE MOTOR
HEATIMG ELEMENT
MAGNETRON
POWER 
TRANSFORMER
H.V. RECTIFIER
CAPACITOR
0.94µ
RY4RY5
RY6
RY1
SECONDARY
INTERLOCK
SWITCH
120V
60Hz
TTMFM
COM.
(RY1)
E-5 E-4 E-3E-2 E-1F-3 F-2 F-1
RY3RY2
PRIMARY 
INTERLOCK
RELAY
N.O.
(RY1)
COM.
(RY3)
COM.
(RY2)
N.O.
(RY2)
N.O.
(RY3)
A-9 A-7
CMDMOL
MAGNETRON 
TEMPERATURE
FUSE
FUSE
RY2
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The door sensing switch in the primary interlock system is
mounted in the upper position on the latch hook, the second-ary interlock switch is mounted in the lower position on 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. A cook cycle cannot take place until the door 
						

							11
R-930CS
condition develops in the magnetron due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the temperature fuse will
open at 302ûF(150ûC) causing the oven to shut down.
CONV. THERMAL CUT-OUT
The thermal cut-out located on the left side of the thermal
protection plate (left) is designed to prevent damage to the
heater unit if an over heated condition develops in the heat-
ing unit due to convection fan failure, thermistor failure,
obstructed air ducts, dirty or blocked air intake, etc. Under
normal operation, the thermal cut-out remains closed. How-
ever, when abnormally high temperatures are reached within
the heater unit, the thermal cut-out will open at 302ûF(150ûC)
causing the oven to shut down. When the thermal cut-out has
cooled, the thermal cut-out closes at 266ûF(130ûC).
HEATING ELEMENT
The heating element is located at the left side of the oven
cavity. It is intended to heat air driven by the convection fan.
The heated air is kept in the oven and force-circulated and
reheated by the heating element.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system where food
is not directly heated by the heating element, but is heated by
forced circulation of the hot air produced by the heating
element. The air heated by the heating element is circulated
through the convection passage provided on the outer casing
of the oven cavity by means of the convection fan which is
driven by the convection motor. It then enters the inside of the
oven through the vent holes provided on the left side of the
oven. Next, the hot air heats the food on the turntable and
leaves the oven cavity through the vent in the center of the
oven cavity left side wall. Without leaving the oven, this hot air
is reheated by the heating element, passes through the
convection passage and enters the inside of the oven cavity
again, in a continuing cycle. In this way, the hot air circulates
inside the oven cavity to raise its temperature and, at the same
time, comes into contact with the food being cooked. When the
temperature inside the oven cavity reaches the selected
temperature, the heating element is de-energized. When the
temperature inside the oven cavity drops below the selected
temperature, the heating element is energized again. In this
way, the inside of the oven cavity is maintained at approxi-
mately the selected temperature. When the convection time
reaches 0, the heating element is de-energized and the
convection fan stops operating and the oven shuts off.
DAMPER OPEN-CLOSE MECHANISM
Usually, the damper is in the open position except during
convection cooking. Damper position is set automatically
by damper motor, damper switch, motor cam and damper
shaft. These components are operated by a signal that
judges if microwave cooking or convection cooking opera-
tion is selected by the control unit.
Microwave Cooking:
Damper is in the open position, because a portion of cooling 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.
Figure D-1. Door sensing switch, monitor switch and
secondary interlock switches
MONITOR SWITCH
The monitor switch is mounted on the middle position of latch
hook. It is activated (the contacts opened) by the lower latch
head 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 second-
ary interlock switch fail to open when the door is opened.
Functions:
1. When the door is opened, the monitor switch contact
close (to the ON condition) due to their being normally
closed. At this time the door sensing and secondary
interlock switches 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 and
secondary interlock switch contacts fail to 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, SECONDARY
INTERLOCK SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION. (RE-
FER TO CHAPTER ÒTEST PROCEDUREÓ).
NOTE: MONITOR FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY.
THERMISTOR
The thermistor is a negative temperature coefficient type.
The temperature in the oven cavity is detected through the
resistance of the thermistor, and then the control unit
causes the heater relay to operate, thus the current to the
heating element is turned ON/OFF.
MAGNETRON TEMPERATURE FUSE.
The temperature fuse located on the waveguide is designed
to prevent damage to the magnetron if an over heated
LATCH HOOK
DOOR SENSING
SWITCH
MONITOR SWITCH
SECONDARY
INTERLOCK SWITCH
SWITCH LEVER
OPEN LEVER
DOOR OPEN 
BUTTON
MONITOR FUSE
LATCH 
HEADS
DOOR OPEN 
BUTTON 
						

							12
R-930CS
air is channelled through the cavity to remove steam and
vapors given off from the heating foods. It is then exhausted
at the top of the oven cavity into a condensation compartment.
Convection Cooking:
Damper is in the closed position, so that no hot air will be
allowed to leak out the oven cavity.
Damper Operation
1. When power supply cord is plugged in:
1-1. When power supply cord is plugged in, a signal is
sensed in the control unit, and operates shut-off
relay (RY4).
1-2. Contacts of shut-off relay (RY4) close, the damper
motor is energized, opening the damper door.
1-3. When the damper is moved to the open position by
the damper cam the damper switch is closed (ON
position).
1-4. The signal from damper switch is re-sensed in the
control unit and shut-off relay (RY4) is turned off.
1-5. The 120  volts A.C. to the damper motor is removed
and the motor turns off.
2. When oven is microwave cooking:
Damper is in the open position.
3. When oven is convection cooking:
3-1.Damper motor is energized by touching the
convection, temperature and START pads.
3-2. When damper is in the closed position (damperswitch is OFF), its signal is sensed by the control
unit, and shut-off relay (RY4) is de-energized.
3-3. The damper is held in the closed position during the
convection cooking operation.
3-4. At the end of the convection cooking, shut-off relay
(RY4) is energized, and the damper is returned to
the open position.
NOTE: If the damper door is not in the proper position,
closed during convection or open during microwave,
the control unit will stop oven operation after 1
minute.
Figure D-2. Damper Mechanism
DAMPER DUCT
DAMPER 
DAMPER CAM
DAMPER MOTORDAMPER SWITCH DAMPER SHAFT
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-
BA012WRK0 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. 
						

							13
R-930CS
A MAGNETRON
B POWER TRANSFORMER
C H.V. RECTIFIER ASSEMBLY
D HIGH VOLTAGE CAPACITOR
E SECONDARY INTERLOCK SWITCH
F PRIMARY INTERLOCK SYSTEM
G MONITOR SWITCH
H MONITOR FUSE
I MAGNETRON TEMPERATURE FUSE
J CONV. THERMAL CUT-OUT
K CONVECTION HEATER
L THERMISTOR
M DAMPER MOTOR
N DAMPER SWITCH
P TOUCH CONTROL PANEL
Q KEY UNIT
R RELAY RY-1
R RELAY RY-2
R RELAY RY-3
R RELAY RY-4
R RELAY RY-5
R RELAY RY-6
S COMP. DEFROST
T FOIL PATERN ON PWB.
U AH SENSOR
ReplaceOVEN LAMP OR SOCKET
ReplaceFAN MOTOR
ReplaceTURNTABLE MOTOR
ReplaceCONVECTION MOTOR
CheckLOOSE WIRING
CheckSHORTED IN POWER CORD
CheckNO POWER AT OUTLET
CheckLOW VOLTAGE
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
CONDITIONCOOKING CONDITION(MICROWAVE)
(CONVECTION)(SENSOR
COOKING)OFF CONDITION
Home fuse blows when power cord is plugged into wall receptacle.
Monitor fuse blows when power cord is plugged into wall receptacle
88:88 does not appear in display when power cord is first plugged into
wall receptacle.
Display does not operate properly when STOP/CLEAR pad is touched.
(The time of day should appear on the display with beep sound.)
Oven lamp does not light with door opened.
Oven lamp does not light in cook cycle. (It light when door is opened).
Cooking cycle runs 1 minute then shuts down.
Oven lamp light, but turntable motor does not operate.
Turntable motor operates normally but cooling fan motor does not
operate.
Oven does not go into a cook cycle, when START pad is touched.
Low or no power is produced during microwave cooking (The food is
heated incompletely or not heated at all)
Extremely uneven heating is produced in oven load (food).
Function of variable cooking does not operate properly except HIGH
power.
Function of COMPU DEFROST does not operate  properly.
CONV indicator lights, but oven does not go into cook cycle when
START pad is touched.
CONV indicator lights, but heating element does not heat.
Temperature in the oven cavity is lower or higher than preset.
Cooling fan motor runs intermittently or all the time.
Convection cycle runs 4 minutes and 15 seconds then shuts down.
Oven in the sensor cooking condition but AH sensor does not end or AH
sensor turns off about max. 30 min. after start.
PROBLEM 
						

							14
R-930CS
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check
across the magnetron filament leads should indicate less than 1 ohm.
5. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads
and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance
the magnetron is grounded and must be replaced.
6. Reconnect all leads removed from components during testing.
7. Reinstall the outer case (cabinet).
8. Reconnect the power supply cord after the outer case is installed.
9. Run the oven and check all functions.
MICROWAVE OUTPUT POWER
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (outer case fitted).
HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE, SO EXTREME CAUTION SHOULD
BE OBSERVED.
Power output of the magnetron can be measured by performing a water temperature rise test. This test
should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following
components or wiring: silicon rectifier, high voltage capacitor and power transformer. This test will require
a 16 ounce (453cc) measuring cup and an accurate mercury thermometer or thermocouple type
temperature tester. For accurate results, the following procedure must be followed carefully:
1. Fill the measuring cup with 16 oz. (453cc) of tap water and measure the temperature of the water with
a thermometer or thermocouple temperature tester. Stir the thermometer or thermocouple through
the water until the temperature stabilizes. Record the temperature of the water.
2. Place the cup of water in the oven. Operate oven at POWER 10(HIGH) 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 22
to 43ûF(12.2 to 23.8ûC) 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.
AMAGNETRON ASSEMBLY TEST
BPOWER TRANSFORMER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of
the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be
approximately 81.7 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. 
						

							15
R-930CS
CHIGH VOLTAGE RECTIFIER 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. 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. 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.
NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts.
ESECONDARY INTERLOCK SWITCH 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. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal
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. 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.
FPRIMARY INTERLOCK SYSTEM TEST
DOOR SENSING SWITCH
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. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal
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.
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
DHIGH VOLTAGE CAPACITOR 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. 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 terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate
continuity for a short time and should indicate an open circuit once the capacitor is charged. If the
above is not the case, check the capacitor with an ohmmeter to see if it is shorted between either of
the terminals and case. If it is shorted, replace the capacitor.
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. (HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO
MEASURE THE FILAMENT AND HIGH VOLTAGE.) 
						

							16
R-930CS
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
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.
NOTE: If the door sensing switch contacts fail in the open position and the door is closed, the turntable
motor and oven light will be activated by RY1.
PRIMARY INTERLOCK RELAY (RY2)
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 two (2) wire leads from the male tab terminals of the Primary Interlock Relay (RY2). Check
the state of the relay contacts using a ohmmeter. The relay contacts should be open. If the relay
contacts are closed, replace the circuit board entirely or the relay itself.
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.
GMONITOR SWITCH
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. Before performing this test, make sure that the secondary interlock switch and the primary interlock
relay are operating properly, according to the above Switch Test Procedure. Disconnect the wire
lead from the monitor switch (COM) terminal. Check the monitor switch operation by using the
ohmmeter as follows. When the door is open, the meter should indicate a closed circuit. When the
monitor switch actuator is pushed by a screw driver through the lower latch hole on the front plate
of the oven cavity with the door opened (in this condition the plunger of the monitor switch is pushed
in), the meter should indicate an open circuit. If improper operation is indicated, the switch may be
defective. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM)
terminal and check the continuity of
the monitor circuit.
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.
SCREW DRIVERMONITOR SWITCH
OHMMETER
SECONDARY
INTERLOCK
SWITCH
COM. N.C.
HBLOWN MONITOR FUSE
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. If the monitor fuse is blown when the door is opened, check the primary interlock relay, secondary
interlock switch and monitor switch according to the TEST PROCEDURE for those switches before
replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK
RELAY, SECONDARY INTERLOCK SWITCH, DOOR SENSING SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION.
If the monitor fuse  is blown by improper switch operation, the monitor fuse and monitor switch must be
replaced with monitor fuse and monitor switch assembly part number FFS-BA012WRK0, even if the
monitor switch operates normally. The monitor fuse and monitor switch assembly is comprised of a 20
ampere fuse and switch. 
						

							17
R-930CS
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
IMAGNETRON TEMPERATURE FUSE 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. A continuity check across the temperature fuse terminals should indicate a closed circuit unless the
temperature of the magnetron reaches approximately 302ûF(150ûC). An open temperature fuse
indicates overheating of the magnetron. Check for restricted air flow to the magnetron, especially the
cooling duct and cooling fan.
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.
CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERA-
TURE, REPLACE TEMPERATURE FUSE.
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. A continuity check across the thermal cut-out terminals should indicate a closed circuit unless the
temperature of the thermal cut-out reaches approximately 302ûF(150ûC). The thermal cut-out resets
automatically at approximately 266ûF(130ûC). If thermal cut-out has opened under normal condition,
replace the same item as in the parts list.
An open thermal cut-out indicates overheating of the heater unit. Check for restricted air flow to the
heater unit through the vent holes of the oven cavity, especially the heater duct and convection fan.
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.
CAUTION: IF THE THERMAL CUT-OUT INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE,
REPLACE THERMAL CUT-OUT.
KHEATING ELEMENT 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. Make sure the heating element is fully cooled and test as follows;
a. Disconnect wire leads from the heating element and measure the resistance with an ohmmeter.
On the R x 1 scale, the resistance between the heating element terminals should be approximately
10.2W.
b. Disconnect wire leads from the heating element  and measure the insulation resistance with 500V
- 100MW insulation resistance meter. The insulation resistance between heating element terminal
and cavity should be more than 0.5MW.
5. If the meter does not indicate above resistance, replace the thermistor
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. 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.
JCONV. THERMAL CUT-OUT TEST 
						

							18
R-930CS
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. Disconnect the wire leads from the switch terminals and connect ohmmeter leads to the common
(COM.) and normally open (N.O.) terminals of the switch.
6-1. When switch actuator is pushed by the damper motor cam, the meter should be indicated a closed
circuit.
6-2.When power cord is plugged into the wall receptacle, the damper motor operates and damper cam will
start to rotate. When the switch actuator is released, the meter should be indicated an open circuit.
7. If improper operation is indicated, replace the damper switch.
8. Disconnect the power supply cord, and then remove outer case.
NDAMPER SWITCH TEST
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT 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 connector-E from the control unit. Measure the resistance of the thermistor with an
ohmmeter. Connect the ohmmeter leads to Pin NoÕs E-3 and E-4.
Room Temperature Resistance
68ûF(20ûC) - 86ûF(30ûC) Approx. 350kW - 155KW
5. If the meter does not indicate above resistance, replace the thermistor.
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.
LTHERMISTOR TEST
MDAMPER MOTOR TEST
When the power cord is plugged into the wall receptacle and 120 volts A.C. is supplied to the damper
motor, the motor operates until the damper is opened and the damper switch closes. Then the damper
motor stops operation.
If the damper motor does not operate, check for A.C. voltage with a voltmeter at the motor.
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. Disconnect the wire leads of motor and connect the meter leads to the wire leads of main wire harness.
7. Re-connect the power cord into the wall receptacle.
8. If 120 volts A.C. is indicated at the wire leads, replace the motor and  if 120 volts A.C. is not indicated,
check the wire harness and control unit.
9. Disconnect the power supply cord, and then remove outer case.
10.Open the door and block it open.
11.Discharge high voltage capacitor.
12.Reconnect all leads removed from components during testing.
13.Re-install the outer case (cabinet).
14.Reconnect the power supply cord after the outer case is installed.
15.Run the oven and check all functions.