SERVICE MANUAL
MICROWAVE OVENS
Microwave Oven
 ELECTROLUX HOME PRODUCTS
Corso Lino Zanussi,30
I - 33080 PORCIA /PN (ITALY)
Tel +39 0434 394850
Fax +39 0434 394096
SOI
Edition: 05.2006
SOI 05.06 FV
Publication No.
599 36 78-44
EN/SERVICE/FV
(Middle Solo)
MC2660E (EU)
MC2661E (EU)
MC2660E (CH)
MC2660E (UK)
ZM266ST (EU)
ZM266ST (UK)
QN4040
JMW2061 (A,D)
EM2612 (F)
599 36 78-44
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TABLE OF CONTENTS
CAUTION, MICROWAVE RADIATION / GENERAL IMPORTANT INFORMATION .......................4
SERVICING / GENERAL INFORMATION .......................................................................................4
PRODUCT SPECIFICATIONS.........................................................................................................5
APPEARANCE VIEW.......................................................................................................................6
OPERATING SEQUENCE .............................................................................................................12
FUNCTION OF IMPORTANT COMPONENTS..............................................................................14
TROUBLESHOOTING CHART......................................................................................................15
TEST PROCEDURE ......................................................................................................................16
CONTROL PANEL ASSEMBLY.....................................................................................................23
SERVICING....................................................................................................................................24
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..........................................25
MICROWAVE MEASUREMENT....................................................................................................31
TEST DATA A GLANCE / WIRING / RE-WIRING .........................................................................32
SCHEMATIC DIAGRAMS ..............................................................................................................33
PICTORIAL DIAGRAM...................................................................................................................34
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CAUTION
CAUTION
MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy which may radiate from the
magnetron or other microwave generating devices if it is improperly used or connected. All input
and output microwave connections, waveguides, flanges and gaskets must be secured. Never
operate the device without a microwave energy absorbing load attached.
Never look into an open waveguide or antenna while the device is energized.
GENERAL IMPORTANT INFORMATIONS
This Manual has been prepared to provide Service Engineers with Operation and Service Information.
It is recommended that service engineers carefully study the entire text of this manual, so they will be
qualified to render satisfactory customer service.
WARNING
Note:
The parts marked "*" are used at voltage
more than 250V. (Schematic Diagrams).
WARNING
Never operate the oven until the following points are ensured.
(A) The door is tightly closed.
(B) The door and oven hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
Servicing and repair work must be carried out only by trained
Service Engineers.
All the parts marked ”*” on schematic diagrams are used at
voltages more than 250V.
Removal of the outer wrap gives access to potentials above
250V.
If the Magnetron are damaged may cause undue microwave
exposure.
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PRODUCT SPECIFICATIONS
SPECIFICATION
ITEM
DESCRIPTION
Power Requirements
230 Volts(EU)/230-240 Volts(UK)
50 Hertz
Single phase, 3 wire earthed
1.3 kW
900W watts nominal of RF microwave energy
(measured by way of IEC 60705)
Operating frequency of 2450 MHz
Width 592 mm
Height 460 mm (including foot)
Depth 437 mm
Width 342mm
Height 207mm
Depth 368mm
325 mm
Jog/Touch Control System
Clock (1.00-12.59 or 0.00-23.59) - 12HR or 24HR setting
Microwave Power for Variable Cooking
Repetition Rate;
Power Consumption
Power Output
Case Dimensions
Cooking Cavity
Dimensions
Turntable diameter
Control Complement
HIGH ........................
MEDIUM HIGH ........
MEDIUM ..................
MEDIUM LOW..........
Full power throughout the cooking time
approx. 70% of Full Power
approx. 50% of Full Power
approx. 30% of Full Power
LOW ......................... approx. 10% of Full Power
TIME/WEIGHT/PORTION knob
- Stir
AUTO COOK 1 button
- Turn over
AUTO COOK 2 button
- Weight
COOK FROM FROZEN button
- Portion
MICROWAVE POWER LEVEL button
- Microwave power level
- Cooking in progress
START/QUICK button
STOP button
DOOR OPENING button
- Stir
- Turn over
- Portion
- Weight
- Microwave power
level
Net weight
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- Cooking in progress
Approx, 20 Kg
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APPEARANCE VIEW
OVEN
1 Front trim
2 Oven lamp
3 Control panel
4 Door open button
5 Waveguide cover
6 Oven cavity
7 Seal packing
8 Door seals and sealing surfaces.
9 Fixing points (4 points)
10 Ventilation openings
11 Outer cover
12 Rear cabinet
13 Power supply cord support clip.
14 Power supply cord (EU)
15 Power supply cord (UK)
Turntable support system
Turntable
Turntable
support
Coupling
1. Place the turntable support in the centre of the
oven floor so that it can freely rotate around the
coupling.
2. Place the turntable onto the turntable support so
that it locates firmly into the coupling.
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APPEARANCE VIEW
CONTROL PANEL
MC2660E / MC2661E
1 Digital Display
2 Indicators
The appropriate indicator will flash or light up, just
above each symbol according to the instruction.
When an indicator is flashing, press the
appropriate button (having the same symbol)
or carry out the necessary operation.
Stir
Turn over
Weight
Portion
Microwave power level
Cooking in progress
3 TIMER/WEIGHT/POWER knob
4 COOK FROM FROZEN button
Press to select one of the 3 automatic programmes
5 AUTO COOK 2 button
Press to select one of the 2 automatic programmes
6 AUTO COOK 1 button
Press to select one of the 2 automatic programmes
7 MICROWAVE POWER LEVEL button
8 AUTO DEFROST button
Press to select one of the 5 automatic programmes
9 START/QUICK button
10 STOP button
11 DOOR OPENING button
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APPEARANCE VIEW
CONTROL PANEL
ZM266ST
1 Digital Display
2 Indicators
The appropriate indicator will flash or light up, just
above each symbol according to the instruction.
When an indicator is flashing, press the
appropriate button (having the same symbol)
or carry out the necessary operation.
Stir
Turn over
Weight
Portion
Microwave power level
Cooking in progress
3 TIMER/WEIGHT/POWER knob
4 COOK FROM FROZEN button
Press to select one of the 3 automatic programmes
5 AUTO COOK 2 button
Press to select one of the 2 automatic programmes
6 AUTO COOK 1 button
Press to select one of the 2 automatic programmes
7 MICROWAVE POWER LEVEL button
8 AUTO DEFROST button
Press to select one of the 5 automatic programmes
9 START/QUICK button
10 STOP button
11 DOOR OPENING button
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APPEARANCE VIEW
CONTROL PANEL
QN4040
1 Digital Display
2 Indicators
The appropriate indicator will flash or light up, just
above each symbol according to the instruction.
When an indicator is flashing, press the
appropriate button (having the same symbol)
or carry out the necessary operation.
Stir
Turn over
Weight
Portion
Microwave power level
Cooking in progress
3 TIMER/WEIGHT/POWER knob
4 COOK FROM FROZEN button
Press to select one of the 3 automatic programmes
5 AUTO COOK 2 button
Press to select one of the 2 automatic programmes
6 AUTO COOK 1 button
Press to select one of the 2 automatic programmes
7 MICROWAVE POWER LEVEL button
8 AUTO DEFROST button
Press to select one of the 5 automatic programmes
9 START/QUICK button
10 STOP button
11 DOOR OPENING button
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APPEARANCE VIEW
CONTROL PANEL
JMW2061
1 Digital Display
2 Indicators
The appropriate indicator will flash or light up, just
above each symbol according to the instruction.
When an indicator is flashing, press the
appropriate button (having the same symbol)
or carry out the necessary operation.
Stir
Turn over
Weight
Portion
Microwave power level
Cooking in progress
3 TIMER/WEIGHT/POWER knob
4 COOK FROM FROZEN button
Press to select one of the 3 automatic programmes
5 AUTO COOK 2 button
Press to select one of the 2 automatic programmes
6 AUTO COOK 1 button
Press to select one of the 2 automatic programmes
7 MICROWAVE POWER LEVEL button
8 AUTO DEFROST button
Press to select one of the 5 automatic programmes
9 START/QUICK button
10 STOP button
11 DOOR OPENING button
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APPEARANCE VIEW
CONTROL PANEL
EM2612
1 Digital Display
2 Indicators
The appropriate indicator will flash or light up, just
above each symbol according to the instruction.
When an indicator is flashing, press the
appropriate button (having the same symbol)
or carry out the necessary operation.
Stir
Turn over
Weight
Portion
Microwave power level
Cooking in progress
3 TIMER/WEIGHT/POWER knob
4 COOK FROM FROZEN button
Press to select one of the 3 automatic programmes
5 AUTO COOK 2 button
Press to select one of the 2 automatic programmes
6 AUTO COOK 1 button
Press to select one of the 2 automatic programmes
7 MICROWAVE POWER LEVEL button
8 AUTO DEFROST button
Press to select one of the 5 automatic programmes
9 START/QUICK button
10 STOP button
11 DOOR OPENING button
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OPERATION SEQUENCE
OFF CONDITION
Closing the door activates the door interlock switch (monitored latch switch).
IMPORTANT
When the oven door is closed, the monitor switch contacts COM - NC must be open.
When the microwave oven is plugged in a wall outlet (230V (EU) / 230-240V (UK) 50Hz), the noise filter is
energized.
Figure 0-1 on page 32
NOTE: When the oven door is opened, the oven lamp comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
Enter a desired cooking time by rotating the time/weight knob
and start the oven by touching START pad.
Figure 0-2 on page 32
CONNECTED COMPONENTS RELAY
Oven lamp, Turntable motor
Power transformer
Fan motor
RY1
RY3
RY4
1. The line voltage is supplied to the primary winding of the power transformer. The voltage is converted
to about 3.3 volts A.C. output on the filament winding and high voltage of approximately 2000 volts
A.C. on the secondary winding.
2. The filament winding voltage (3.3 volts) heats the magnetron filament and the high voltage (2000 volts) is
sent to the voltage doubling circuit, where it is doubled to negative voltage of approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the magnetron generates a wave length of 12.24 cm.
This energy is channelled through the waveguide (transport channel) into the oven cavity, where the
food is placed to be cooked.
4. When the cooking time is up, a single tone is heard and the relays RY1 + RY3 + RY4 go back to their
home position. The circuits to the oven lamp, power transformer, fan motor and turntable motor are cut off.
5. When the door is opened during a cook cycle, the switches come to the following condition.
SWITCH
CONTACT
Monitor switch
COM-NC
COM-NO
COM-NO
COM-NO
Monitored latch switch
Stop switch
DURING
COOKING
Open
Closed
Closed
Closed
CONDITION
DOOR OPEN
(NO COOKING)
Closed
Open
Open
Open
The circuits to the power transformer, fan motor and turntable motor are cut off when the monitored latch
switch is opened. The oven lamp remains on even if the oven door is opened after the cooking cycle has been
interrupted, because the relay RY1 stays closed. Shown in the display is the remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch (SW2) is mechanically controlled by oven door, and monitors the operation of the
monitored latch switch (SW1)
6-1 When the oven door is opened during or after the cycle of a cooking program, the monitored latch
switch (SW1), and stop switch (SW3) must open their contacts (COM-NO) first. After that the
contacts (COM - NC) of the monitor switch (SW2) can be closed.
6-2 When the oven door is closed, the contacts (COM - NC) of the monitor switch (SW2) must be
opened first. After that the contacts of the monitored latch switch (SW1) and stop switch (SW3)
are closed.
6-3 When the oven door is opened and the contacts of the monitored latch switch (SW1) remain closed,
the fuse (F1) F8A will blow, because the monitor switch is closed and a short circuit is caused.
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OPERATION SEQUENCE
HIGH, MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW COOKING
When the microwave oven is preset for variable cooking power, the line voltage is supplied to the power
transformer intermittently within a 32-second time base through the vary contact. The following levels of
microwave power are given.
SETTING
HIGH
MEDIUM HIGH
Approx.
MEDIUM
Approx.
MEDIUM LOW
Approx.
LOW
Approx.
NOTE: The ON/OFF time ratio does not exactly correspond to the percentage of microwave power,
because approx. 3 seconds are needed for heating up the magnetron filament.
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FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM
The door can be opened by pushing the door open button.
MONITORED LATCH SWITCH (SW1)
1. When the oven door is closed, the contacts
(COM - NO) must be closed.
2. When the oven door is opened, the contacts
(COM - NO) must be opened.
DOOR
LATCH HOOK
MONITOR
SWITCH (SW2)
MONITORED
LATCH
SWITCH (SW1)
MONITOR SWITCH (SW2)
1. When the oven door is closed, the contacts
(COM - NC) must be opened.
2. When the oven door is opened, the contacts
(COM - NC) must be closed.
3. If the oven door is opened and the contacts
(COM - NO) of the monitored latch switch
(SW1) fail to open, fuse F8A blows
simultaneously with closing the contacts
(COM - NC) of the monitor switch (SW2).
LATCH
HEADS
STOP
SWITCH
SW3
OPEN LEVER
DOOR OPEN BUTTON
STOP SWITCH (SW3)
1. When the oven door is closed, the contacts
(COM - NO)must be closed.
Figure D-1. Door Open Mechanism
2. When the oven door is opened, the contacts (COM - NO) must be opened.
CAUTION: BEFORE REPLACING A BLOWN FUSE (F1 AND F2) TEST THE MONITORED LATCH
SWITCH (SW1) AND MONITOR SWITCH (SW2) FOR PROPER OPERATION.
(REFER TO CHAPTER "TEST PROCEDURE".)
THERMAL CUT-OUT 125°C TC01 (OVEN)
The thermal cut-out located on the top of the oven cavity is designed to prevent damage to the oven 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 thermal cut-out remains closed. However, when abnormally high
temperatures are reached within the oven cavity, the oven thermal cut-out will open at 125°C, causing the oven
to shut down. The defective thermal cut-out must be replaced with a new one.
THERMAL CUT-OUT 125°C TC02 (MG)
This thermal cut-out protects the magnetron against overheat. If the temperature goes up higher than 125°C
because the fan motor is interrupted or the ventilation openings are blocked, the thermal cut-out TC02 will open
and line voltage to the high voltage transformer T will cut off and operation of the magnetron MG will be
stopped. The defective thermal cut-out must be replaced with a new one.
TURNTABLE MOTOR
The turntable motor drives the turntable roller assembly to rotate the turntable.
FAN MOTOR
The fan motor drives a blade which draws external cool air. This cool air is directed through the air vanes
surrounding the magnetron and cools the magnetron. This air flows through the oven cavity to remove steam
and vapours given off from the heating foods. It is then vented through the exhaust air vents at the rear of oven
cavity.
NOISE FILTER
The noise filter prevents the radio frequency interference that might flow back in the power circuit.
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TROUBLESHOOTING CHART
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 fuse F1. Check the monitored latch
switch and monitor switch before replacing the F8A fuse.
CONDITION
PROBLEM
Home fuse blows when power cord is
plugged into wall outlet.
D E E E F F G H I
● ●
"88:88"does not operate in display
when power cord is plugged into wall
outlet.
OFF
CONDITION
●
●
●
● ●
● ●
●
●
Display does not operate properly
when STOP button is touched.
●
● ●
Oven lamp does not light, when door
is opened. (Display operates).
●
●
Oven does not start when START
button is touched.(Display operates).
●
● ● ●
●
●
●
●
●
●
●
Fan motor does not operate (Oven
lamp lights).
●
Turntable motor assembly does not
operate (Oven lamp lights).
●
Oven or electrical parts does not stop
when timer knob is at "0" or STOP
button is touched.
●
●
Display operates properly but all
electrical parts do not operate.
COOKING
CONDITION
I J J K L M
NOISE FILTER
TURNTABLE MOTOR
FAN MOTOR
TC TRANSFORMER
CONTROL UNIT
SWITCH UNIT
RELAY RY1,3,4
FOIL PATTERN ON P.W.B.
POWER SUPPLY CORD
SHORTED WIRE HARNESS
OPENED WIRE HARNESS
OVEN LAMP
BLOCKED VENTILATION OPENINGS
WRONG OPERATION
MIS-ADJUSTMENT OF SWITCHES
HOME FUSE OR BREAKER
NO POWER AT WALL OUTLET
BLOKED COOLING FAN
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
A B C
MAGNETRON
HIGH VOLTAGE TRANSFORMER
H.V. RECTIFIER ASSY
H.V. HARNESS
HIGH VOLTAGE CAPACITOR
MONITORED LATCH SWITCH
STOP SWITCH
MONITOR SWITCH
MAG THERMAL CUT-OUT 125°C
THERMAL CUT-OUT 125°C (OVEN)
FUSE F1
TEST PROCEDURE
Oven goes into cook cycle but shuts
down before end of cooking cycle.
Oven seems to be operating but little
or no heat is produced in oven load
(Microwave power control is set at
HIGH).
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Oven does not seem to be operating
properly during variable cooking
condition(Oven operates properly at
HIGH).
Fuse F8A blows (F2)
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599 36 78-44
TEST PROCEDURES
PROCEDURE
LETTER
A
COMPONENT TEST
MAGNETRON TEST
NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN
INSULATED TOOL WHILE THE OVEN IS IN OPERATION.
CARRY OUT 3D CHECK
Isolate the magnetron from high voltage circuit by removing all leads connected to
the filament terminal.
To test for an open circuit filament use an ohmmeter to make a continuity test
between the magnetron filament terminals, the meter should show a reading of less
than 1 ohm.
To test for a short circuit filament to anode condition, connect ohmmeter between
one of the filament terminals and the case of the magnetron (ground). This test
should be indicated an infinite resistance.
If a low or zero resistance reading is obtained then the magnetron should be
replaced.
MICROWAVE OUTPUT POWER (IEC-60705-1988)
The following test procedure should be carried out with the microwave oven in a
fully assembled condition (outer case fitted). Microwave output power from the
magnetron can be measured by way of IEC 60705. To measure the microwave
output power in the microwave oven, the relation of calorie and
watt is used. When P(W) heating works for t(second), approximately
P x t/4.187 calorie is generated. On the other hand, if the temperature of the water
with V(ml) rises ∆T (°C) during this microwave heating period, the calorie of the
water is V x ∆T.
The formula is as follows;
P x t / 4.187 = V x ∆ T
P (W) = 4.187 x V x ∆T / t
Our condition for water load is as follows:
Room temperature..........................around 20°C
Power supply Voltage.....................Rated voltage
Water load......................................1000 g
Initial temperature...........................10 ± 2°C
Heating time....................................47 + 3 = 50 sec.
P = 90 x ∆T
Measuring condition:
1. Container
The water container must be a cylindrical borosilicate glass vessel having a
maximum material thickness of 3 mm and an outside diameter of approximately
190 mm.
2. Temperature of the oven and vessel.
The oven and the empty vessel are at ambient temperature prior to the start of
the test.
3. Temperature of the water
The initial temperature of the water is (10 ± 2)°C.
4. Select the initial and final water temperature so that the maximum difference
between the final water temperature and the ambient temperature is 5K.
5. Select stirring devices and measuring instruments in order to minimize addition or
removal of heat.
6. The graduation of the thermometer must be scaled by 0.1°C at minimum and an
accurate thermometer.
7. The water load must be (1000 ± 5) g.
8. “t” is measured while the microwave generator is operating at full power.
Magnetron filament heat-up time is not included.
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TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
NOTE: The operation time of the microwave oven is “t + 3” sec. 3 seconds are
needed for magnetron filament heat-up time.
Measuring method:
1. Measure the initial temperature of the water before the water is added to the
vessel.
(Example: The initial temperature T1 = 11°C)
2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the turntable.
4. Operate the microwave oven at HIGH for the temperature of the water rises
by a value ∆T of (10 ± 2) K.
5. Stir the water to equalize temperature throughout the vessel.
6. Measure the final water temperature. (Example: The final temperature
T2 = 21°C)
7. Calculate the microwave power output P in watts from above formula.
Initial temperature ............................................................................. T1 = 11°C
Temperature after (47+ 3) = 50 sec................................................... T2 = 21°C
Temperature difference Cold-Warm...................................................T∆ = 10°C
Measured output power
The equation is “P = 90 x ∆T” .................................. P = 90 x 10°C = 900Watts
JUDGEMENT: The measured output power should be at least ± 15 % of
the rated output power.
CAUTION: 1°C CORRESPONDS TO 90 WATTS. REPEAT
MEASUREMENT IF THE POWER IS INSUFFICIENT.
Heat up for 50 sec.
B
POWER TRANSFORMER TEST
WARNING: High voltages and large currents are present at the
secondary winding and filament winding of the power
transformer. It is very dangerous to work near this part when
the oven is on. NEVER make any voltage measurements of
the high-voltage circuits, including the magnetron filament.
CARRY OUT 3D CHECKS
Disconnect the leads to the primary winding of the power transformer.
Disconnect the filament and secondary winding connections from the rest of
the HV circuitry. Using an ohmmeter, set on a low range, it is possible to check
the continuity of all three windings. The following readings should be
obtained:a. Primary winding ............ 2 ohms approximately
b. Secondary winding ....... 160 ohms approximately
c. Filament winding ........... less than 1 ohm
If the reading obtained are not as stated above, then the power transformer is
probably faulty and should be replaced.
CARRY OUT 4R CHECKS
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TEST PROCEDURES
PROCEDURE
LETTER
E
COMPONENT TEST
SWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the
terminals as described in the following table.
Table: Terminal Connection of Switch
Plunger Operation
COM to NO
COM to NC
COM; Common terminal
Released
Open circuit
Short circuit
NO;
Normally open terminal
Depressed
Short circuit
Open Circuit
NC;
Normally close terminal
If incorrect readings are obtained, replace the switch.
CARRY OUT 4R CHECKS.
F
THERMAL CUT OUT TEST
CARRY OUT 3D CHECKS
Disconnect the leads from the terminals of the thermal cut-out. Then using an
ohmmeter, make a continuity test across the two terminals as described in the
below.
CARRY OUT 4R CHECKS
Table: Thermal Cut-out Test
Parts Name
Temperature of
"ON" condition
(closed circuit).
(°C)
Temperature of
"OFF" condition
(open circuit).
(°C)
Thermal cut-out
125°C TC01
Thermal cut-out
125°C TC02
This is not
reset able type
This is not
reset able type
Above 125°C
Indication of
ohmmeter
(When room
temperature is
approx. 20°C.)
Closed circuit
Above 125°C
Closed circuit
If incorrect readings are obtained, replace the thermal cut-out.
An open circuit thermal cut-out (MG) TC02 indicates that the magnetron has
overheated, this may be due to restricted ventilation, cooling fan failure.
An open circuit thermal cut-out (OVEN) TC01 indicates that the oven cavity
has overheated, this may be due to no load operation.
G
BLOWN FUSE F8A (F1)
CARRY OUT 3D CHECKS
If the fuse F8A (F1) is blown when the door is opened, check the primary
latch switch, monitor switch and monitor resistor.
If the fuse F8A (F1) is blown by incorrect door switching replace the
defective switch(es) and the fuse F8A (F1).
CARRY OUT 4R CHECKS
CAUTION: Only replace fuse with the correct value replacement.
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TEST PROCEDURES
PROCEDURE
LETTER
H
COMPONENT TEST
NOISE FILTER TEST
CARRY OUT 3D CHECKS
Disconnect the leads from the
terminals of the noise filter.
Using an ohmmeter, check between
the terminals as described in the
following table.
MEASURING POINTS
Between N and L
Between terminal N and WHITE
Between terminal L and RED
INDICATION OF OHMMETER
Open circuit
Short circuit
Short circuit
If Incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS
I
MOTOR WINDING TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor. Using an ohmmeter, check the
resistance between the two terminals as described in the table below.
Table: Resistance of Motor
Motors
Resistance
Fan motor
Approximately 290 Ω
Turntable motor
Approximately 12 - 15 kΩ
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
LIVE TEST FOR MOTOR WINDING
CAUTION: The following procedure requires the oven to be connected
to the supply and should only be used if the relevant "cold"
checks for the motor under test are inconclusive.
1. CARRY OUT 3D CHECKS.
2. Disconnect the leads from the primary of the high voltage transformer. Make
sure that the leads remain isolated from other oven components and
chassis (Use insulation tape if necessary).
3. Connect the voltmeter, set to 250V AC, across the motor terminals. (Refer
to the relevant motor test procedure or pictorial diagram for the correct
terminal numbers.)
4. Arrange the meter in a position where it can be read during the test.
(Do not touch the meter, meter leads or oven circuitry while the oven is
active.)
5. Close the oven door.
6. Set the power level to 900W and set the relevant timer for about three (3)
minutes.
7. Note the reading on the meter and carefully observe the motor under test to
see if it is turning.
8. CARRY OUT 3D CHECKS.
9. Remove the test meter leads.
10.Reconnect the leads to the primary of the high voltage transformer.
If a reading of the line voltage was obtained (step 7) but the motor was not
turning then it is faulty and should be replaced. If the meter indicated that the
no supply was present then the winding to the motor should be O.K.. Other
circuit checks should be made, i.e. relays, switches.
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TEST PROCEDURES
J
TOUCH CONTROL PANEL ASSEMBLY TEST
The touch control panel consists of circuits including semiconductors such as
LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper
maintenance can not be performed with only a voltmeter and ohmmeter.
In this service manual, the touch control panel assembly is in four units,
Control unit, Switch Unit, LED Unit and Relay Unit. Troubleshooting by unit
replacement is described according to the symptoms indicated.
1. Switch Unit.
NOTE: Check switch unit lead wire harness connection
before replacement.
The following symptoms indicate a defective switch unit. Replace the
switch unit.
a) When touching the keys, a certain key produces no signal at all.
b) When touching a key, two figures or more are displayed.
c) When touching the keys, sometimes a key produces no signal.
2. Control Unit
The following symptoms indicate a defective control unit. Before replace
the control unit, perform the switch unit test (Procedure L) to determine if
control unit is faulty.
2-1 In connection with keys.
a) When touching a key, a certain group of keys do not produce a signal.
b) When touching a key, no keys produce a signal.
2-2.In connection with indicators.
a) At a certain digit, all or some dots do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light up.
d) The corresponding dots of all digits do not light up; or they continue to
light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
h) When touching a tact switch, the control unit does not respond.
2-3.Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
3. LED Unit
a) No backlight behind display.
b) Dull backlight behind display.
K
SWITCH UNIT TEST
If the display fails to clear when the STOP key is depressed, first verify the lead
wire harness is marking good contact, verify that the stop switch operates properly;
that is the contacts are closed when the door is closed and open when the door is
open. If the stop switch is good, disconnect the lead wire harness that connects the
switch unit to the control unit and make sure the stop switch is closed (either close
the door or short the stop switch connecter). Use the switch unit matrix indicated on
the switch unit circuit and place a jumper wire between the pins that correspond to
the STOP key making momentary contact. If the control unit responds by clearing
with a beep the switch unit is faulty and must be replaced. If the control unit does
not respond, it is a faulty and must be replaced. If a specific key does not respond,
the above method may be used (after clearing the control unit) to determine if the
control unit or switch unit is at fault.
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TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
MC2660E(EU/UK/CH) MC2661E(EU/UK)
ZM266ST (EU/UK) QN4040 JMW2061 EM2612
SW
1
2
3
4
5
6
7
8
9
USAGE
Start/Quick
Not Used
Stop
Power Level
Not Used
Auto Defrost
Cook from Frozen
Auto Cook 2
Auto Cook 1
L
RELAY TEST
Remove the outer case and check voltage between Pin No 1and Pin No 3 of the 3 pin
connector (A) on the control unit with an A.C. voltmeter.
The meter should indicate rated voltage, if not check oven circuit.
RY1,RY3 and RY4 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking
operation.
DC. voltage indicated ............. Defective relay.
DC. voltage not indicated ....... Check diode which is connected to the relay
coil. If diode is good, control unit is defective.
RELAY SYMBOL
SOI 05.06 FV
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 12.0V D.C.
Oven lamp / Turntable motor
RY3
Approx. 12.0V D.C.
High voltage transformer
RY4
Approx. 12.0V D.C.
Fan motor
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599 36 78-44
TEST PROCEDURES
PROCEDURE
LETTER
M
COMPONENT TEST
PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE
PRINTED WIRING BOARD (PWB) IS OPEN
To protect the electronic circuits, this model is provided with a fine foil pattern added to
the input circuit on the PWB, this foil pattern acts as a fuse. If the foil pattern is open,
follow the troubleshooting guide given below for repair.
Problem: POWER ON, indicator does not light up.
STEPS
OCCURRENCE
CAUSE OR CORRECTION
Check supply voltage and oven power
cord.
3
The rated AC voltage is not
present between Pin No. 5-1 of the
3 pin connector (CNA)
The rated AC voltage is not
present at primary side of low
voltage transformer.
Pattern at "a" and "b" are broken.
4
Pattern at "c" and "d" are broken.
1
2
Low voltage transformer or secondary
circuit defective.
check and repair.
*Insert jumper wire J1 and solder.
(CARRY OUT 3D CHECKS BEFORE
REPAIR)
*Insert the coil code 5028 24 08-00/9
between "c" and "d (J1).
(CARRY OUT 3D CHECKS BEFORE
REPAIR)
NOTE: *At the time of making these
repairs, make a visual
inspection of the varistor.
Check for burned damage. If
any abnormal condition is
detected, replace the
defective parts.
CARRY OUT 4D CHECKS
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CONTROL PANEL ASSEMBLY
OUTLINE OF CONTROL PANEL
The touch control section consists of the following units as shown in the touch control panel circuit.
(1) Switch Unit
(2) Control Unit
(3) LED Unit
(4) Relay Unit
The principal functions of these units and the signals communicated among them are explained below.
Switch Unit
The switch unit is composed of a matrix, signals generated in the LSI are sent to the switch unit
through P22, P23 and P24.
When a switch button is touched, a signal is completed through the switch unit and passed back to the
LSI through P50 and P51 to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, relay circuit, back light circuit, synchronizing signal
circuit, reset circuit, buzzer circuit, and indicator circuit.
1) LSI
This LSI controls the tact switch strobe signal, relay driving signal, for oven function and indicator
signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control unit.
Symbol
VC
Voltage
-5.0V
Application
LSI(IC1)
3) Synchronizing Signal Circuit
The power source synchronizing signal is available in order to compose a basic standard time in
the clock circuit. It accompanies a very small error because it works on commercial frequency.
4) ACL Circuit
A circuit to generate a signals which resets the LSI to the initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit audible sounds (tact switch touch sound
and completion sound).
6) Stop Switch
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, turntable motor and light the oven lamp.
8) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-common electrodes using a Liquid Crystal Display.
9) Encoder
The encoder converts the signal generated by LSI into the pulse signal, and the pulse signal is
returned to the LSI.
10) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1 - LD3).
LED Unit
A circuit consisting of three light emitting diodes (LD1- LD3)which are driven by the control unit
and provide the backlight for the display.
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SERVICING
1. Precautions for Handling Electronic
Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following
precautions should be strictly followed. CMOS LSI
have extremely high impedance at its input and
output terminals. For this reason, it is easily
influenced by the surrounding high voltage power
source, static electricity charge in clothes,
etc. and sometimes it is not fully protected by the
built-in protection circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap
them in aluminium foil. Also wrap all PW boards
containing them in aluminium foil.
2) When soldering, ground the technician as
shown in the figure and use grounded soldering
iron and work table.
approx. 1 M ohm
2. Servicing of Touch Control Panel
We describe the procedures to permit servicing
of the touch control panel of the microwave
oven and the precautions you must take when
doing so. To perform the servicing, power to the
touch control panel is available either from the
power line of the oven itself or from an external
power source.
(1) Servicing the touch control panel with
power line of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF
THE MICROWAVE OVEN IS STILL LIVE
DURING SERVICING AND PRESENTS A
HAZARD.
Therefore, before checking the performance of
the touch control panel,
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 these leads remain isolated from
other components and oven chassis by using
insulation tape.
6) After that procedure, re-connect the power
supply cord.
After checking the performance of the touch
control panel,
1) Disconnect the power supply cord.
2) Open the door and block it open.
3) Re-connect the leads to the primary of the
power transformer.
4) Re-install the outer case (cabinet).
SOI 05.06 FV
5) Re-connect the power supply cord after the
outer case is installed.
6) Run the oven and check all functions.
A. On some models, the power supply cord
between the touch control panel and the oven
itself is so short that the two can’t be separated.
For those models, check and repair all the
controls (sensor-related ones included) of
the touch control panel while keeping it
connected to the oven.
B. On some models, the power supply cord
between the touch control panel and the oven is
long enough that they may be separated from
each other. For those models, it is possible to
check and repair the controls of the touch
control panel while keeping it apart from the
oven; in this case you must short both ends of
the door sensing switch (on PWB) of the touch
control panel with a jumper, which activates an
operational state that is equivalent to the oven
door being closed.
(2) Servicing the touch control panel with
power supply from an external power
source:
Disconnect the touch control panel completely
from the oven, and short both ends of the door
sensing switch (SW3: STOP SWITC on PWB
CNB connector 1 and 2) of the touch control
panel, which activates an operational state that
is equivalent to the oven door being closed.
Connect an external power source to the power
input terminal of the touch control panel, then it
is possible to check and repair the controls of
the touch control panel.
3. Servicing Tools
Tools required to service the touch control panel
assembly.
1) Soldering iron: 30W
(It is recommended to use a soldering iron with
a grounding terminal.)
2) Others: Hand tools
4. Other Precautions
1) Before turning on the power source of the
control unit, remove the aluminium foil applied
for preventing static electricity.
2) Connect the connectors of the key unit to the
control unit being sure that the lead wires are
not twisted.
3) After aluminium foil is removed, be careful that
abnormal voltage due to static electricity etc. is
not applied to the input or output terminals.
4) Attach connectors, electrolytic capacitors, etc.
to PWB, making sure that all connections are
tight.
5) Be sure to use specified components where
high precision is required.
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below
before operating the oven.
1. CARRY OUT 3D CHECKS.
2. Make sure that a definite "click" can be heard
when the microwave oven door is unlatched.
(Hold the door in a closed position, then
push the door open button slowly. This
causes the latch heads to rise, it is then
possible to hear a "click" as the door
switches operate.)
3. Visually check the door and cavity face plate
for damage (dents, cracks, signs of arcing
etc.).
Carry out any remedial work that is necessary
before operating the oven.
Do not operate the oven if any of the following
conditions exist;
1. Door does not close firmly.
2. Door hinges or latch hook is damaged.
3. The door seal is damaged.
4. The door is bent or warped.
5. There are defective parts in the door interlock
6. There are defective parts in the microwave
generating and transmission assembly.
7. There is visible damage to the oven.
system.
Do not operate the oven:
1. Without the RF gasket (Magnetron).
2. If the wave guide or oven cavity are not intact.
3. If the door is not closed.
4. If the outer case (cabinet) is not fitted.
Please refer to ‘OVEN PARTS, CABINET PARTS, DOOR PARTS’, when carrying out any of the following
removal procedures:
BUILT IN FRAME ASSEMBLY REMOVAL
To remove the built in frame assembly, proceed
as follows.
1. Remove the four screws securing the frame
assembly to the oven cavity, (two from the
top and two from the hinge side).
2. Remove the two screws securing the frame
assembly to the control panel frame
(accessed from the back of the frame).
3. Open the oven door fully.
4. Un-clip the built in frame assembly at the
5. Pull the built in frame assembly away from the cavity
face
6. Now the built in frame assembly is free.
TOP
SCREWS
C.P. SECURING
SCREWS
HINGE SIDE
SCREWS
bottom.
OUTER CASE REMOVAL
To remove the outer case, proceed as follows.
1. Disconnect oven from power supply.
2. Open door and wedge open.
3. Remove the two screws from the rear
intake duct.
4. Slide the rear intake duct up and pull it
away from the oven cavity.
5. Remove the screws from the rear(4), along
the side edges(4 hinge side, 3 control panel
side) and from the top(2 control panel side).
SOI 05.06 FV
6. Slide the entire case back about 3cm to free it from
the retailing clips on the cavity face plate.
7. Lift the entire case from the oven.
8. Discharge the H.V capacitor before carrying any further
work.
9. Do not operate the oven with the outer case
removed.
CAUTION: DISCHARGE HIGH VOLTAGE
CAPACITOR BEFORE TOUCHING ANY
OVEN COMPONENTS OR WIRING.
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
HIGH VOLTAGE COMPONENTS REMOVAL
(HIGH VOLTAGE CAPACITOR AND HIGH VOLTAGE RECTIFIER ASSEMBLY)
To remove the components, proceed as
follows.
1. CARRY OUT 3D CHECKS
2. Disconnect the filament lead of the high
voltage transformer secondary wire from
high voltage capacitor.
3. Disconnect the high voltage wire B from the
magnetron.
4. Remove one (1) screw holding earth side
terminal of high voltage rectifier assembly.
5. Remove one (1) screw holding fan duct to
the oven cavity rear plate.
6. Remove one (1) screw holding the capacitor
from the oven cavity rear plate.
7. Release the capacitor holder from the fan
duct.
8. Remove the high voltage capacitor from the capacitor
holder.
9. Disconnect the high voltage wire B and the high voltage
rectifier assembly from the high voltage capacitor.
10. Disconnect the high voltage rectifier assembly from
the high voltage wire B.
11. Now, the high voltage rectifier assembly and the high
voltage capacitor should be free.
CAUTION:
WHEN REPLACING HIGH VOLTAGE
RECTIFIER ASSEMBLY, ENSURE THAT
THE CATHODE (EARTH) CONNECTION IS
SECURELY FIXED TO THE CAPACITOR.
HIGH VOLTAGE TRANSFORMER REMOVAL
1. CARRY OUT 3D CHECKS
2. Disconnect the filament leads of the power
transformer from high voltage capacitor and the
magnetron.
3. Disconnect the H.V. secondary wire from the
power transformer.
4. Disconnect the leads of the transformer
primary.
5. Remove the two (2) screws holding the transformer to
base plate.
6. Remove the transformer from the base plate by sliding
it away from the oven cavity and lifting it.
7. Now, the power transformer is free.
MAGNETRON REMOVAL
1. CARRY OUT 3D CHECKS.
2. Disconnect the H.V. wire B and filament lead of
the transformer from the magnetron.
3. Remove the one (1) screw holding the chassis
support to the magnetron
4. Move the air intake duct to left.
5. Carefully remove three (3) screws holding the
magnetron to the waveguide. When removing
the screws hold the magnetron to prevent it from
falling.
6. Remove the magnetron from the waveguide with
care so the magnetron antenna is not hit by any
metal object around the antenna.
7. Ensure the magnetron wiringis re-fitted in accordance
with the pictorial diagram on page 33 (F and FA)
CAUTION: WHEN REPLACING THE MAGNETRON,
BE SURE THE R.F. GASKET IS IN PLACE AND
THE MAGNETRON MOUNTING SCREWS ARE
TIGHTENED SECURELY.
CONTROL PANEL ASSEMBLY REMOVAL
1. CARRY OUT 3D CHECKS.
2. Disconnect the main wire harness from the
control panel.
3. Remove the one (1) screw holding the control
panel to the oven cavity.
4. Lift the control panel assembly and pull it forward. Now,
the control panel assembly is free.
TURNTABLE MOTOR REMOVAL
1. Disconnect the oven from the power supply.
2. Remove the turntable motor cover by snipping
off the material in four corners.
3. Where the corners have been snipped off bent
corner areas flat. No sharp edge must be
evident after removal of turntable motor cover.
4. Disconnect the wire leads from the turntable motor
and remove the one (1) screw holding the
turntable motor.
5. Turntable motor is now free.
6. After replacement use one (1) screw to fit the
turntable motor cover.(code 5028 05 76-00/5).
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
FAN MOTOR REPLACEMENT
REMOVAL
CAUTION:
1. CARRY OUT 3D CHECKS.
2. Remove the one (1) screw holding the noise
filter to the chassis support.
3. Release the noise filter from the tabs of the
fan duct.
4. Remove the one (1) screw holding the
chassis support to the oven cavity front
flange.
5. Remove one (1) screw holding the chassis
support to the magnetron.
6. Remove the chassis support from the oven
cavity.
7. Disconnect the wire leads from the fan duct.
8. Remove the one (1) screw holding the
capacitor holder to the oven cavity back
plate.
9. Release the tabs of the capacitor holder from
the fan duct.
10.Remove the one (1) screw holding the fan
duct to the oven cavity back plate.
11.Remove the fan duct from the oven.
12.Remove the fan duct from the fan motor
shaft according to the following procedure.
1) Hold the edge of the rotor of the fan motor by
using a pair of groove joint pliers.
CAUTION:
Make sure that no swarf from the
rotor enters the gap between the
rotor & stator of the fan motor.
Avoid touch the coil of the fan motor
with the pliers as the coil may
become cut or damaged. Avoid
deforming the bracket whilst using
the pliers.
2) Remove the fan blade assembly from the
shaft of the fan motor by pulling and
rotating the fan blade with your hand.
3) Now, the fan blade will be free.
CAUTION:
Do not reuse the removed fan blade as the
fixing hole may be oversize.
13. Remove the two (2) screws holding the fan motor
to the fan duct.
14. Now, the fan motor is free.
INSTALLATION
1. Install the fan motor to the fan duct with the two (2)
screws.
2. Install the fan blade to the fan motor shaft according
to the following procedure.
1) Hold the centre of the bracket which supports
shaft of the fan motor on a flat table.
2) Apply the screw lock tight into the hole (for shaft)
of the fan blade.
3) Install the fan blade to the shaft of fan motor by
pushing the fan blade with a small, light weight,
ball peen hammer or rubber mallet.
CAUTION:
Do not hit the fan blade when installing
because the bracket may be deformed.
Make sure that the fan blade rotates
smoothly after installation.
Make sure that the axis of the shaft is not
slanted.
3. Insert the tabs of the capacitor holder to the fan
duct.
4. Install the fan duct to the oven cavity back plate
with the one (1) screw.
5. Install the capacitor holder to the oven cavity
back plate with the one (1) screw.
6. Re-install the chassis support to the cavity back
plate with the one (1) screw.
7. re-fit one (1) screw to secure the chassis support
to the magnetron.
8. Install the noise filter to the fan duct and the
chassis support with the one (1) screw.
9. Re-connect the wire leads to the fan motor.
Shaft
Center of
bracket
Table
Coil
Groove joint pliers
Stator
Gap
Rotor
Bracket
Shaft
Axis
Rear view
Stator
These are the position
that should be pinched
with pliers
Rotor
Side view
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
OVEN LAMP REMOVAL
1. CARRY OUT 3D CHECKS.
2. Disconnect the wire lead from the oven lamp
3. Lift up the oven lamp from the clips of the air
intake duct.
4. Now, the oven lamp is free.
Lock
Bulb
Socket
Oven lamp
POWER SUPPLY CORD REPLACEMENT
Removal
1. CARRY OUT 3D CHECKS.
2. Remove the one (1) screw holding the
green/yellow wire to the cavity back plate.
3. Disconnect the leads of the power supply cord
from the noise filter, referring to the Figure
C-4(a).
4. Release the power supply cord from the rear
cabinet.
5. Now the power supply cord is free.
Oven cavity back plate
Re-install
1. Insert the moulding cord stopper of power supply cord
into the square hole of the power angle, referring
to the Figure C-4(b).
2. Install the earth wire lead of power supply cord to the
oven cavity with one (1) screw and tight the screw.
3. Connect the brown and blue wire leads of power
supply cord to the noise filter correctly, referring to the
Pictorial Diagram.C-4(a).
Power supply cord
Screw
Green / Yellow
Wire
POWER
SUPPLY CORD
Blue Wire
OVEN CAVITY
BACK PLATE
Brown Wire
Noise filter
Figure C-4 (a) Replacement of Power Supply Cord
SOI 05.06 FV
SQUARE HOLE
Figure C-4 (b). Installation of Power Supply Cord
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
MONITORED LATCH SWITCH, MONITOR SWITCH AND STOP SWITCH REMOVAL
1. CARRY OUT 3D CHECKS.
2. Remove the control panel assembly
referring to "CONTROL PANEL
ASSEMBLY REMOVAL".
3. Disconnect the all leads from the
switches.
4. Remove the two (2) screws holding the
latch hook to the oven cavity.
5. Remove the latch hook.
6. Push the retaining tab slightly and remove
the switch.
MONITOR SWITCH
TAB
MONITORRED
LATCH SWITCH
TAB
STOP SWITCH
TAB
Figure C-2. Latch Switches
MONITORED LATCH SWITCH, MONITOR SWITCH AND STOP
SWITCH ADJUSTMENT
If the monitored latch switch, stop switch and
monitor switch do not operate properly due
to a mis-adjustment, the following adjustment
should be made.
1. CARRY OUT 3D CHECKS.
2. Loosen the two (2) screws holding the
latch hook to the oven cavity front flange.
3. With the door closed, adjust the latch
hook by moving it back and forward, or up
and down. In and out play of the door
allowed by the latch hook should be less
than 0.5mm. The horizontal position of
the latch hook should be placed where the
monitor switch has activated with the door
closed. The vertical position of the latch
hook should be placed where the
monitored latch switch and stop switch
have activated with the door closed.
4. Secure the screws firmly.
5. Make sure of the monitored latch switch,
stop switch and monitored switch
operation. If those switches have not
activated with the door closed, repeat step
1 - 4.
After adjustment, make sure of following:
1. In and out play of door remains less than
0.5mm when patches position. First
check latch hook position, pushing and
pulling upper position of the door toward
the oven face. The results (play of the
door) should be less then 0.5mm.
SOI 05.06 FV
2. The contacts (COM-NO) of monitored latch switch
and stop switch interrupt the circuit before the door
can be opened.
3. The contacts (COM-NC) of the monitor switch
close when door is opened.
4. Re-install outer case and check for microwave
leakage around the door with an approved
microwave survey meter. (Refer to Microwave
Measurement procedure.)
DOOR
LATCH HOOK
MONITOR
SWITCH (SW2)
MONITORED
LATCH
SWITCH (SW1)
LATCH
HEADS
STOP
SWITCH
(SW3)
OPEN LEVER
DOOR OPEN BUTTON
Figure C-3. Latch Switch Adjustments
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
DOOR DISASSEMBLY
REMOVAL
1. Disconnect the power supply cord.
2. Open the door slightly and remove the built
in frame assembly(Ref: to chapter built in
frame assembly removal).
3. Remove the choke cover taking care not
to break clips by inserting an iron plate
(thickness of about 0.5mm) or flat type
screw driver to the gap between the choke
cover and door panel as shown Figure C-4
to free the engaged parts.
4. Release choke cover from door panel.
5. Now choke cover is free.
Choke Cover
Putty Knife
Door Frame
Figure C-4. Door Disassembly
6. Release two (2) pins of door panel from
two (2) holes of upper and lower oven
hinges by lifting up.
7. Remove door assy by removing screws
(4).
8. Release door panel from tabs of door
frame and remove door frame.
9. Now, door panel with inner sealer film is
free.
10.Tear inner sealer film from door panel.
11.Now, door panel is free.
12.Slide latch head upward and remove it
from door frame with releasing latch spring
from door frame and latch head.
13.Now, latch head and latch spring are free.
Note: After any service to the door;
(A) Make sure that monitored latch switch, stop switch and
monitor switch are operating properly. (Refer to chapter
“Test Procedures , Switch Test page 21”.).
(B) An approved microwave survey meter should be used
to assure compliance with proper microwave
radiation emission limitation standards.
After any service, make sure of the following :
1. Door latch heads smoothly catch latch hook through latch
holes and that latch head goes through centre of latch hole.
2. Deviation of door alignment from horizontal line of cavity face
plate is to be less than 1.0mm.
3. Door is positioned with its face pressed toward cavity face
plate.
4. Check for microwave leakage around door with an
approved microwave survey meter. (Refer to Microwave
Measurement Procedure.)
Note: The door on a microwave oven is designed to act as an
electronic seal preventing the leakage of microwave
energy from oven cavity during cook cycle. This function
does not require the door be air-tight, moisture
(condensation)-tight or light-tight. Therefore, occasional
appearance of moisture, light or sensing of gentle warm
air movement around oven door is not abnormal and
does not indicate leakage of microwave energy from the
oven cavity.
PIN
DOOR SUB
ASSEMBL
SLIT CHOCHE
DOOR
PANEL
LOWER
OVEN HINGE
RE-INSTALL
1. Re-install latch spring to the head.
Reinstall latch spring to the door frame.
Reinstall latch head to the door frame.
2. Re-install door panel to door frame by
fitting tabs of door frame to holes of door
panel.
3. Put sealer film on door panel. Refer to
“Inner Sealer Film” and figure C-6, on how
to handle the new film.
4. Catch two (2) pins of door panel on two (2)
hole of upper and lower oven hinges.
5. Re-install choke cover to door panel by
pushing.
SOI 05.06 FV
UPPER
OVEN HINGE
CHOKE COVER
PIN
LOWER
OVEN HINGE
Figure C-5. Door Replacement
NOTE: When carrying out any repair to the door, do not
bend or warp the slit choke (tabs on the door panel
assembly) to prevent microwave leakage.
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COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
INNER SEALER FILM
Door film
Backing film
Installation
1. Tear away the backing film.
3. Put the pasted side of the inner sealer film
on the door panel.
Figure C-6. Inner Sealer Film
MICROWAVE MEASUREMENT
After adjustment of door latch switches, monitor
switch and door are completed individually or
collectively, the following leakage test must be
performed with a survey instrument and it must be
confirmed that the result meets the requirements
of the performance standard for microwave oven.
REQUIREMENT
The safety switch must prevent microwave
radiation emission in excess of 5mW/cm2 at any
point 5 cm or more from external surface of the
oven.
PREPARATION FOR TESTING:
Before beginning the actual test for leakage,
proceed as follows;
1. Make sure that the test instrument is operating
normally as specified in its instruction booklet.
Important:
Survey instruments that comply with the
requirement for instrumentations as prescribed
by the performance standard for microwave
ovens must be used for testing.
Recommended instruments are:
NARDA 8100
NARDA 8200
HOLADAY HI 1500
SIMPSON 380M
2. Place the oven tray into the oven cavity.
3. Place the load of 275 ± 15 ml of water initially at
20 ± 5°C in the centre of the oven tray. The water
container should be a low form of 600 ml beaker with
inside diameter of approx. 8.5 cm and made of an
electrically non-conductive material such as glass or
plastic.
The placing of this standard load in the oven is
important not only to protect the oven, but also to
insure that any leakage is measured accurately.
4. Close the door and turn the oven ON with the timer
set
for several minutes. If the water begins
to boil
before the survey is completed, replace it with 275ml of
cool
water.
5. Move the probe slowly (not faster that 2.5cm/sec.)
along the gap.
6. The microwave radiation emission should be
measured at any point of 5 cm or more from the
external surface of the oven.
Microwave leakage measurement at 5 cm distance
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TEST DATA AT A GLANCE
Parts
Thermal cut-out (OVEN)
Oven lamp
High voltage capacitor
Symbol
TC01
OL
C
Magnetron
MG
Power transformer
T
Fuse
Thermal cut-out (Magnetron)
F1
TC02
Value / Data
125°C
240-250V 25W
1.02µF AC 2100V (EU)
0,97µF AC 2100V (UK)
Filament < 1Ω
Filament – chassis ∞ ohm.
Filament winding < 1Ω
Secondary winding Approx. 160 Ω.
Primary winding Approx. 2 Ω.
F8A 250V
125°C
WIRING/RE-WIRING
WARNING: WIRING / RE-WIRING.
Before carrying out any work; carry out 3D
checks.
1. Disconnect the supply
2. Door opened and wedge open.
3. Discharge the high voltage capacitor.
RE-WIRING.
Ensure the following:
1. Wires must not touch:
a) High voltage parts.
(Magnetron, high voltage transformer, high
voltage capacitor and high voltage
rectifier).
c) Sharp edges.
(Bottom plates, oven cavity, waveguide
flange, chassis support and other metallic
parts).
d) Movable parts.
( Fan blade, any motor, switch).
2. Positive lock connectors are fitted correctly.
Ensure the locking pin is located correctly.
3. Wires are connected correctly as per pictorial
diagram.
4. No wire leads are trapped by the outer wrap.
b) Parts that become hot.
(Heating elements, oven lamp, oven cavity
magnetron and high voltage transformer).
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599 36 78-44
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ASYMMETRIC
RECTIFIER
MONITOR
SWITCH
MONITORED
SWITCH
LATCH
MAGNETRON
THERMAL
CUT OUT
CONTROL UNIT
LIVE
F1
FUSE
TURNTEBLE MOTOR
OVEN LAMP
FAN MOTOR
H.V.RECTIFIER
CAPACITOR
STOP
SWITCH
NOISE SOPPRESSION COIL
EARTH
FUSE
OVEN
THERMAL
CUT OUT
NOISE
FILTER
UNIT
ASYMMETRIC
RECTIFIER
MONITOR
SWITCH
MONITORED
LATCH
SWITCH
MAGNETRON
THERMAL
CUT OUT
TURNTEBLE MOTOR
OVEN LAMP
FAN MOTOR
H.V.RECTIFIER
CAPACITOR
SWITCH
STOP
F1
FUSE
LIVE
CONTROL UNIT
NOISE SOPPRESSION COIL
EARTH
OVEN
THERMAL
CUT OUT
NOISE
FILTER
UNIT
SCHEMATIC DIAGRAMS
Figure 0-1 Oven Schematic-OFF Condition, Door Closed.
Figure 0-2 Oven Schematic-ON Condition, Door Closed.
599 36 78-44
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LED BOARD
CONTROL UNIT
SWITCH UNIT
MONITORED LATCH SWITCH
MONITOR SWITCH
STOP SWITCH
TURNTEBLE MOTOR
MAGNETRON
THERMAL
CUT-OUT
OVEN LAMP
OVEN
THERMAL
CUT-OUT
FAN MOTOR
MAINS SUPPLY CORD
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POWER TRANSFORMER
H.V.
RECTIFIER
H.V. CAPACITOR
SHORT
PROTECTOR
HIGHT VOLTAGE COMPONENTS
NOISE FILTER UNIT
PICTORIAL DIAGRAMS
Figure S-1 Pictorial Diagram .
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