Sharp R-cd1800m Service Manual

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[3] DESCRIPTION AND FUNCTION OF COMPONENTS
1. DOOR OPEN MECHANISM
1. The handle lever is pulled.
2. The upper and lower latch heads are lifted up by the linked latch
lever.
3. The latch lever is lifted up by the handle lever.
4. Now both latch heads are lifted up, so they can be released from
the latch hook.
5. Now the door can be opened.
Figure D-1. Door Open Mechanism
2. DOOR SENSING SWITCH
The door sensing switch is activated by the latch head of the door and
switch lever C. When the door is opened, the contacts of the switch
open and interrupt the circuit to the coils of the primary interlock relay.
The contacts of the primary relay then open and interrupt the circuit to
the primary winding of the power transformers.
3. SECONDARY INTERLOCK SWITCHES (1), (2)
The secondary interlock switches (1), (2) are activated by the upper
latch head of the door and switch lever B. When the door is opened,
the contacts of the switch open and interrupt the circuit to the primary
winding of the power transformers (1), (2).
4. MONITOR SWITCHES (1), (2)
The monitor switches (1), (2) are mounted in the upper position of the
latch hook. The monitor switches are activated by the upper latch head
of the door and switch lever A. When the door is opened, the contacts
of the monitor switches close. Monitor switch (1) 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
(1) fail to open when the door is opened. Monitor switch (2) is intended
to render the oven inoperative by means of blowing the monitor fuse,
when the contacts of the primary interlock relay and secondary inter-
lock switch (2) fail to open when the door is opened.
Functions:
With the door shut, the contacts of the door sensing switch and the
secondary interlock switches (1), (2) are closed and the contacts of the
monitor switches (1), (2) are open.
1. When the door is opened, the contact of the door sensing switch
and secondary interlock switches (1), (2) are opened first, then the
contact of the monitor switches (1), (2) are closed.
2. As the door goes to a closed position, the contacts of the monitor
switches (1), (2) are opened first, then the contacts of the door
sensing switch and the secondary interlock switches (1), (2) close.3. If the door is opened, and the contacts of the primary interlock relay
and secondary interlock switch of the same circuit fail to open, the
monitor fuse blows simultaneously with closing of the monitor
switch contacts of that circuit (1 or 2).
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST
THE DOOR SENSING SWITCH, PRIMARY INTERLOCK
RELAY, SECONDARY INTERLOCK SWITCHES (1), (2),
DOOR SENSING SWITCH AND MONITOR SWITCHES
(1), (2) FOR PROPER OPERATION. (REFER TO CHAP-
TER “TEST PROCEDURE”).
NOTE: MONITOR FUSE AND SWITCH ARE REPLACED AS AN
ASSEMBLY.
5. MONITOR FUSE
1. The monitor fuse blows when the contacts (COM-NO) of the pri-
mary interlock relay (RY1) 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 short-circuited, this
monitor fuse blows to prevent an electric shock or fire hazard.
6. MAGNETRON TEMPERATURE FUSES (1), (2)
The temperature fuses (1), (2) located on the top of the upper and
lower waveguide, are designed to prevent damage to the magnetrons
(1), (2). If an over heated condition develops in the tube due to blower
motor failure, obstructed air ducts, dirty or blocked air intake, etc., the
circuit to the magnetrons are interrupted. Under normal operation, the
temperature fuses remains closed. However, when abnormally high
temperatures are generated within the magnetron, the temperature
fuse will open at 302°F (150°C) causing the microwave energy to stop.
The defective temperature fuse must be replaced with new rated one.
7. OVEN TEMPERATURE FUSE
The temperature fuse, located on the side of the exhaust duct assem-
bly, 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 temperature fuse will open. Under normal operation, the oven tem-
perature fuse remains closed. However, when abnormally high tem-
peratures are generated within the oven cavity, the oven temperature
fuse will open at 248°F (120°C), causing the oven to shut down. The
defective temperature fuse must be replaced with new rated one.
8. EXHAUST THERMISTOR
The exhaust thermistor is located on the side of the exhaust duct
assembly. The temperature in the exhaust duct is detected through the
resistance of the thermistor. If the temperature is high, the control
panel will display”EE7” and the oven will stop to avoid overheating and
catching fire. If the thermistor is open, the control panel will display
“EE8” and the oven will stop.
9. MAGNETRON THERMISTOR
The thermistor is a negative temperature coefficient type. The air tem-
perature around the upper and lower magnetrons is detected through
the resistance of the thermistor. If the temperature is high, the control
panel will display “EE7” and the oven will stop to protect the magne-
trons against overheat. If the magnetron thermistor is open, the control
panel will display “EE8” and the oven will stop.
10. FAN MOTORS
The fan motors drive blades which draw external cool air into the oven.
This cool air is directed through the air vanes surrounding the magne-
trons and cools the magnetrons. This air is channelled through the
oven cavity to remove steam and vapours given off from the heating
foods. It is then exhausted through the exhausting air vents at the
oven cavity. 
Latch hook Latch
lever
Monitor switch (2)
Secondary
interlock switch (2)
Secondary
interlock switch (1)
Door sensing switch Monitor switch (1) Switch lever A
Switch lever B
Switch lever C Latch
head
Latch
head Handle
lever 
						

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During cooking, they operate. After cooking, they will operate at least
for 1 minute and the maximum operating time is 4 minutes. When the
temperature of the magnetron thermistor becomes bellow 110°C, the
fan motors will stop. These two (2) fan motors are D.C. motors.
11. EXHAUST MOTOR
The exhaust motor is located on the side of the exhaust duct assem-
bly. This motor drives a blade in the exhaust duct assembly. The
driven blade draws the external cool air into the oven from the intake
duct assembly. Then it sends the air out of the oven through the
exhaust duct assembly. During cooking, the exhaust motor operates.
After cooking, it will operate at least for 1 minute and the maximum
operating time is 4 minutes. When the temperature of the exhaust
thermistor becomes bellow 65°C, the exhaust motor will stop. This
motor is D.C. motor. 
NOTE: Do not disconnect the power supply from the exhaust motor
when it is turned on. Or it may be out of order.
12. ANTENNA MOTORS
The upper and lower antenna motors drive antennas to radiate the
microwave.
13. EXHAUST FAN
The exhaust fan is located to the rear cover. It sends the air (which is
at the top of the oven cavity) out of the oven. This motor is D.C. motor.
14. ANTENNA SENSOR
The antenna sensors are located to the top and bottom of the oven
cavity. And they watch if the antennas are rotating or not.
15. MIROWAVE SENSOR
The microwave sensor is located on the top of the oven cavity. And it
watch if the microwave is radiated into the oven cavity or not.
16. FUSE 12A (1) (2)
1. If the wire harness or electrical components are short-circuited, this
fuse blows to prevent an electric shock or fire hazard.
2. The fuse also blows when the asymmetric rectifier, H.V. rectifier,
H.V. wire harness, H.V. capacitor, magnetron or secondary winding
of high voltage transformer is shorted.
17. H.V. ASYMMETRIC RECTIFIER (1) (2)
The H.V.asymmetric rectifiers (1) (2) are solid state devices that pre-
vent current flow is both directions. And they prevent the temperature
rise of the high voltage transformers (1) (2) by blowing the fuses 12A
(1) (2) when the high voltage rectifiers (1) (2) are shorted. The rated
peak reverse voltage of D1 of the asymmetric rectifier is 6 KV. The
rated peak reverse voltage of D2 of the asymmetric rectifier is 1.7 KV.
D1 and D2 of the asymmetric rectifier or high voltage rectifier are
shorted when the each peak reverse voltage goes beyond the each
rated peak reverse voltage. (The process of the blowing the fuse 12A.)
NOTE: The H.V.asymmetric rectifier is assembled with the high volt-
age rectifier actually.
1. The high voltage rectifier is shorted by some fault when microwave
cooking or dual cooking.
2. The peak reverse voltage of D2 of the rectifier goes beyond the
rated peak reverse voltage 1.7 KV in the voltage doubler circuit.
3. D2 of the rectifier is shorted.4. The large electric currents flow through the high voltage winding of
the high voltage transformer.
5. The large electric currents beyond 12A flow through the primary
winding of the high voltage transformer.
6. The fuse 12A blows by the large electric currents.
7. The power supplying to the high voltage transformer is cut off.
18. OVEN LAMP
The oven cavity light illuminates the interior of the oven so that food
being cooked can be examined visually through the door window with-
out having to open the door. 
19. NOISE FILTER
The noise filter prevents the radio frequency interference that might
flow back in the power circuit.
D2 D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE
RECTIFIER 
						

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Home fuse blows when power cord is plugged into wall
receptacle
It seems that the output power is lower or higher than
the rated one. Monitor fuse blows when power cord is plugged into wall
receptacle.
" . " does not appear in display when power cord is first
plugged into wall receptacle.
Oven lamp does not go on for 1 minute after door is opened.
Oven lamp and antenna motors do not go on in cook cycle.
Oven goes into a cook cycle but shuts down before and off
cooking cycle.
Oven does not go into cook cycle when START pad is touched.
Low or no power is produced during cooking condition. (The
food is heated incompletely or not heated at all.)
Variable cooking does not operates properly, except HIGH
power functions.
Fan motor does not operate.
Exhaust fan does not operate.
Exhaust motor does not operate.
Oven doen not go into cook cycle when START pad on the
door is touched.
OFF
CONDITION CONDITION
PROBLEM
COOKING
CONDITION
POSSIBLE CAUSE AND
DEFECTIVE PARTSTEST PROCEDURE
MAGNETRON (1), (2)
POWER TRANSFORMER (1), (2)
H.V. RECTIFIER ASSEMBLY (1), (2)
HIGH VOLTAGE CAPACITOR (1), (2)
SECONDARY INTERLOCK SWITCH (1), (2)
PRIMARY INTERLOCK SYSTEM
DOOR SENSING SWITCH
MONITOR SWITCH (1), (2)
MONITOR FUSE
MAGNETRON TEMP. FUSE (1), (2)
OVEN TEMPERATURE FUSE
OVEN LAMP OR SOCKET
FAN MOTORS
EXHAUST FAN
EXHAUST MOTOR
FUSE 12A (1), (2)
VOLTAGE SELECT RELAY (1), (2)
EXHAUST THERMISTOR
MAGNETRON THERMISTOR
NOISE FILTER
KEY UNITS
POWER UNIT
RELAY UNIT
CONTROL UNIT
SWITCH UNIT.
AIR FLOW BLOCKED
LOOSE WIRING
SHORT IN POWER SUPPLY CORD
NO POWER AT OUTLET
LOW POWER SUPPLY VOLTAGE
AB CDEF FGH
JJ I LK NPQOM 
						

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SPECIFICATION OF ERROR
Outline Operation when error occurs Display in operation usually
When a basic performance and the function are ruined Displaying  and heating stop EE0, EE1, EE2, EE3, EE8
When the dangers of the state of the high temperature and the ignition, etc. are 
foreseenDisplaying  and heating stop EE7
When you mistake the setting of the heating time Operation stop EE9
When neither the power supply nor the environmental condition are proper Operation stop EE4, EE5, EE6
When informing of the exchange time of parts Display Only CC1, CC2, CC3, CC4
Display for maintenance
Error his-
tory displayContent of maintenance Check itemParts to be 
replaced
CC1 CC2 CC3 CC4
{– MG1 exchange time information Using time of MG1 MG1
{– MG2 exchange time information Using time of MG2 MG2
{– Exhaust Fan motor exchange time information Using time of Exhaust motor Exhaust motor
{– T/C unit exchange time information Using number of times of RY2/RY3 Relay unit
A TEST PROCEDURE
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
BDC E F I JK L QORR S
EE0
EE0
EE0
EE0
EE0
EE0
EE0EE1
EE1 EE2
EE2EE3
EE3
EE3EE4
EE5
EE6
EE6EE7
EE7
EE7EE8
EE8
EE8
EE8
EE8
EE8
EE8
EE8
EE8EE9
Magnetron 1and /or 2
Power transformer 1 & 2
High voltage capacitor 1 and /or 2
H.V.rectifier assembly 1 and/or 2Secondary interlock switch 1 and/orPrimary interlock system
Fuse 12A 1 and/or 2
Magnetron temp. fuse 1 and/or 2
Magnetron thermistor 1 and/or 2
Exhaust thermistor
Fan motors
Exhaust motor
Antenna motor 1 and/or 2
Air flow blocked
Low or High power supply voltage
No load or small load operation
Loose wiring
Exceeding of maxmum cooking time
Burned food
Relay unit
Control unit
Antenna sensor (1) (Upper)
Antenna sensor (2) (Lower)
Microwave sensor
EE 1Failer of high voltage circuit 1EE 2Failer of high voltage circuit 2EE 3Failer of high voltage circuit 1&2EE 4Too high of input voltage(+13%)EE 5Too low of input voltage(-13%)EE 7Food burned (temp., too high)EE 8Melted contacts of relaysEE 9Over maximum cooking timeEE 10EEPROM errorEE 11Life end of magnetron 1EE 21Life end of magnetron 2EE 31Life end of magnetron 1&2EE 81Life end of relays RY2/RY3EE 83Over Current errorEE 14MG1 Cooling Fan lock judgeEE 24MG2 Cooling Fan lock judgeEE 44Exhaust motor lock judgeEE 54Life end of exhaust motorEE 15MG1 antenna rotation errorEE 25MG2 antenna rotation errorEE 35MG1/2 antenna rotation errorEE 16MG1 thermistor openEE 26MG2 thermistor openEE 17MG1 temperature, too high
EE 27MG2 temperature, too high
EE 18Magnetron 1
EE 28Magnetron 2
EE 38Magnetron 1& 2
EE 29Exhaust thermistor open/short
EE 19No food
EE 39small food
Error history
displayUsual error
displayContent of error
If the power supply voltage is higher than 230V+13% (259.9V), EE4 will be displayed.
If the power supply voltage is lower than 208V-13% (180.96V), EE5 will be displayed. NOTE 1:
" " means that the parts should be replaced when EE11, EE21, EE31 or EE81 is indicated on the display. NOTE 2: 
						

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4. Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its highest range.
Connect the ohmmeter across the terminal B+C of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this
second reading. The normal resistance is infinite in one direction and more than 100k ohms in the other direction.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
2. ASYMMETRIC RECTIFIER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge two high voltage capacitors.
4. Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric rectifier can be tested using an ohmmeter set to its highest range
across the terminals A+B of the asymmetric rectifier and note the reading obtained. Reverse the meter leads and note this second reading. If an
open circuit is indicated in both directions then the asymmetric rectifier is good. If the asymmetric rectifier is shorted in either direction, then the
asymmetric rectifier is faulty and must be replaced with high voltage rectifier. When the asymmetric rectifier is defective, check whether magne-
tron, high voltage rectifier, high voltage wire or filament winding of the high voltage transformer is shorted.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are 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.
[4] D: HIGH VOLTAGE CAPACITOR (1) AND/OR (2) TEST
1. Disconnect the power supply cord, and then remove outer case and rear cover.
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 termi-
nals 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 rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[5] E: SECONDARY INTERLOCK SWITCH (1) AND/OR (2) TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
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 rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
D2 D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE
RECTIFIERAB
C 
						

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[6] F: PRIMARY INTERLOCK SYSTEM TEST
1. DOOR SENSING SWITCH
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
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.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are 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 blower motor, stirrer motors and oven light will be acti-
vated by RY1.
2. PRIMARY INTERLOCK RELAY RY1
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
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 RY1. Check the state of the relay contacts using a ohm-
meter. 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 rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[7] G: MONITOR SWITCH (1) AND/OR (2) TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Before performing this test, make sure that the secondary interlock switches (1), (2) and the primary interlock relay RY1 are operating properly,
according to the above Switch Test Procedure. Disconnect the wire lead from the monitor switches (1), (2) (COM) terminals. Check the monitor
switches (1), (2) 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 upper 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 switches, reconnect the wire lead to the monitor switch (COM) terminals and check the continuity of the monitor
circuit.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[8] H: BLOWN MINITOR FUSE TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
Screw Driver
Ohmmeter
Monitor switch (2) Latch hook
Monitor switch (1) 
						

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3. Discharge high voltage capacitor.
4. If the monitor fuse is blown when the door is opened, check the primary interlock relay RY1, secondary interlock switches (1), (2) and monitor
switches (1), (2) according to the “TEST PROCEDURE” for those switches before replacing the blown monitor fuse.
CAUTION: CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE, TEST THE PRIMARY INTERLOCK RELAY, SECONDARY INTERLOCK
SWITCHES, DOOR SENSING SWITCH AND MONITOR SWITCHES 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-BA033WRKZ, even if the monitor switch operates normally. The monitor fuse and monitor switch assembly is
comprised of a 20 ampere fuse and switch.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[9] I: FUSE 12A (1) (2) TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. If the fuse is blown, check the magnetron, high voltage capacitor, high voltage rectifier assembly, according to the “TEST PROCEDURE” before
replacing the blown fuse. Then replace the fuse.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[10] J: TEMPERATURE FUSE TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
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 temperature fuse reaches
specified temperature as shown below.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE TEMPERATURE FUSE.
[11] K: MAGNETRON THERMISTOR TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the connector of the magnetron thermistor from the harness. Measure the resistance of the thermistor with an ohmmeter. Connect the
ohmmeter leads to the connector of the thermistor.
If the meter does not indicate above resistance, replace the thermistor.
5. Reconnect all leads removed from components during testing.Open temperature  Close temperature  Display or 
ConditionCheck point
Magnetron temperature 
fuse (1)
150°C Non resetable typeEE1Magnetron (1) Failure:
Test magnetron (1) and fan motor.
Magnetron temperature 
fuse (2)EE2Magnetron (2) Failure:
Test magnetron (2) and fan motor.
Magnetron temperature 
fuse (1), (2)EE3Magnetron (1), (2) Failure: Test magnetron (1), (2).
Check fan motor and ventilation opening.
Oven temperature fuse 120°C Non resetable type Oven shut offFood has been burned in oven.
Temperature of oven inside is very high.
Room temperature Resistance
68°F (20°C) Approx. 750KΩ 
						

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6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[12] L: EXHAUST THERMISTOR TEST
The exhaust thermistor can be checked by using the Special function (SF-6). Check the exhaust thermistor, referring to the pages of the Exhaust ther-
mistor check (SF-6). 
If the display shows “OH”, the exhaust thermistor is normal. If the display shows “no”, the exhaust thermistor is abnormal and it should be replaced.
[13] M: NOISE FILTER TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the lead wires from the terminal the noise filter. Using an ohmmeter, check between
the terminals as described in the following table. If incorrect reading are obtained, replace the
noise filter.
5. Reconnect all leads removed from components during testing.
6. Reinstall the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord after the rear cover and the outer case are installed.
8. Run the oven and check all functions.
[14] N: KEY UNIT TEST
1. Disconnect the power supply cord, and then remove outer case and rear cabinet.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Check Key unit ribbon connection before replacement.
5. If key unit ribbon connection is normal, carry out the following procedures.
6. Re-install the rear cover and the outer case (cabinet).
7. Reconnect the power supply cord.
8. The following symptoms indicate a defective key unit.
1) When touching the pads, a certain pad produces no signal at all.
2) When touching a number pad, two figures or more are displayed.
3) When touching the pads, sometimes a pad produces no signal.
9. When you can not judge if the key unit is normal or not by using the item 8 above, carry out following test procedures.
1) Disconnect the power supply cord, and then remove outer case and rear cover.
2) Open the door and block it open.
3) Discharge two high voltage capacitors.
4) Disconnect the leads to the primary of the power transformer.
5) Ensure that these leads remain isolated from other components and oven chassis by using
insulation tape.
6) Reconnect the power supply cord.
7) If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon
cable is making good contact, verify that the door sensing switch (stop switch) operates prop-
erly; that is the contacts are closed when the door is closed and open when the door is open.
If the door sensing switch (stop switch) is good, disconnect the flat ribbon cable that connects
the key unit to the control unit and make sure the door sensing switch is closed (either close
the door or short the door sensing switch connector). Use the Key unit matrix indicated on the
control panel schematic and place a jumper wire between the pins that correspond to the
STOP/CLEAR pad making momentary contact. If the control unit responds by clearing with a
beep the key unit is faulty and must be replaced. If the control unit does not respond, it is
faulty and must be replaced. If a specific pad does not respond, the above method may be
used (after clearing the control unit) to determine if the control unit or key pad is at fault. MEASURING POINT INDICATION OF OHMMETER
Between source terminals Approx. 470KΩ
Between source (Black) and load (Black) terminals Short circuit.
Between source (White) and load (White/Brown) terminals Short circuit.
FUSE
20A
NOISE FILTER
NOISE SUPPRESSION COILLINE CROSS CAPACITOR
1.0μF / AC 250V DISCHARGE RESISTOR
470K 1/2W
LINE BYPASS
CAPACITOR
0.0033μF / AC 125V LINE BYPASS
CAPACITOR
0.0033μF / AC 125V
Load
(Black) Load
(White/Brown)Source
(White)Source
(Black)
5432
7
8
9 61
2
3
4 1
5
6
72
3
4 1
5
6
72
3
4 1
5
6
7
8
STOP
CLEAR
1
START
3 4
956
07 8
STOP
CLEAR
12
X2/X3
START
3 4
956
07 8
CN-M
CN-R CN-Z
2
CUSTOM
HELP SET
MEMORYEXPRESS
DEFROSTSELECT
TIME
SELECT
POWER
CN-Q< KEY UNIT >