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Operation

 

2-1

The following is a description of component functions 
during oven operation.

OFF CONDITION

Closing the door activates the door sensing switch and
secondary interlock switch.  (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (See Figure 2-1).

1.   The display will show “ENJOY YOUR OVEN, PRESS
 

CLEAR AND PRESS CLOCK”.  

 

To set any program or set the clock, you must first 
touch the STOP/CLEAR pad.  The display will clear, 
and “ : “ appears. 

 

COOKING CONDITION

Program desired cooking time by touching the NUMBER
pads.  Program the power level by touching the POWER
LEVEL pad and then a Number pad.  

When the START pad is touched, the following operations
occur:
1.   The contacts of relays are closed and components    

connected to the relays are turned on as follows. 

 

(For details, refer to Figure 2-2)

RELAY  CONNECTED COMPONENTS

RY-1  

Oven Lamp / Turntable Motor / Fan Motor

RY-2 Power 

Transformer

2.   120 volts AC is supplied to the primary winding of  

 

the power transformer and is converted to about  

 

3.3 volts AC output on the filament winding, and  

 

approximately 2370 volts AC on the high voltage  

 

winding.

3.   The filament winding voltage heats the magnetron    

filament and the H.V. winding voltage is sent to a  

 

voltage doubler circuit.

4.   The microwave energy produced by the magnetron    

is channeled through the waveguide into the cavity    
feedbox, and then into the cavity where the food  

 

is placed to be cooked.

5.   Upon completion of the cooking time, the power  

 

transformer, oven lamp, etc. are turned off, and the    
generation of microwave energy is stopped.  The  

 

oven will revert to the OFF condition.

6.   When the door is opened during a cook cycle, the
 

monitor switch, door sensing switch, third door 
switch, primary switch relay (RY1) and secondary 
interlock relay are activated with the following results. 
The circuits to the turntable motor, the cooling fan 
motor, and the high voltage components are de-
energized, the oven lamp remains on, and the digital 
read-out displays the time still remaining in the cook 
cycle when the door was opened.

7.   The monitor switch electrically monitors the operation 

of the primary and third door switch and is mechani-
cally associated with the door so that it will function in 
the following sequence.

 

(1)  When the door opens from the closed position,    

 

 

the secondary interlock relay (RY2) secondary    

 

 

switch open their contacts.  And contacts of the    

 

 

relay (RY1) remains closed.  Then the monitor    

  switch 

contacts 

close. 

 

 

 

(2)  When the door is closed from the open position,   
 

the monitor switch contacts open first.  Then the   

 

contacts of the primary switch, third door switch   

 

and door sensing switch close. and the contacts   

 

of the relay (RY1) open. 

If the primary interlock switch and secondary interlock 
relay (RY2) fail with the contacts closed when the door is 
opened, the closing of the monitor switch contacts will 
form a short circuit through the C/T fuse, primary interlock 
switch, relay (RY1) and secondary interlock relay (RY2), 
causing the C/T fuse to blow.

Operating Sequence Description 

Summary of Contents for EI24MO45IBA

Page 1: ...Publication 5995557591 P N 316439602 January 2010 GRAIN DIRECTION ALL PARTS Technical Service Manual Microwave Oven Model EI24MO45IBA ...

Page 2: ......

Page 3: ...ation of any safety device 5 Use ONLY REPLACEMENT PARTS CATALOGED FOR THIS APPLIANCE Substitutions may defeat compliance with Safety Standards Set For Home Appliances 6 GROUNDING The standard color coding for safety ground wires is GREEN or GREEN with YELLOW STRIPES Ground leads are not to be used as current carrying conductors It is EXTREMELY important that the service technician reestablish all ...

Page 4: ...ch Door Monitor Switch 2 3 Turntable Motor 2 4 Cooling Fan Motor 2 4 Monitor Fuse 2 4 Cavity Temperature Fuse 2 4 C T Temperature Fuse 2 4 Sensor Cooking Condition 2 4 Humidity Sensor Circuit 2 5 Section 3 Troubleshooting and Error Codes Warnings and Cautions 3 1 Troubleshooting Guide Chart 3 2 Section 4 Component Teardown and Testing Warnings and Cautions 4 1 Outer Case Removal 4 2 Power Transfor...

Page 5: ...drain the electrostatic charge from your body by touching a known earth ground NEVER OPERATE THE OVEN UNTIL THE FOLLOWING POINTS ARE ENSURED A THE DOOR IS TIGHTLY CLOSED B THE DOOR BRACKETS AND HINGES ARE NOT DEFECTIVE C THE DOOR PACKING IS NOT DAMAGED D THE DOOR IS NOT DEFORMED OR WARPED E THERE IS NO OTHER VISIBLE DAMAGE WITH THE OVEN SERVICING AND REPAIR WORK MUST BE CARRIED OUT ONLY BY TRAINED...

Page 6: ...ion check as per the Microwave Measurement Procedure outlined in this service manual If microwave emissions level is in excess of the specified limit contact ELECTROLUX HOME PRODUCTS INC immediately If the unit operates with the door open service person should 1 Tell the user not to operate the oven 2 Contact Electrolux HOME PRODUCTS INC and Food and Drug Administration s Center for Devices and Ra...

Page 7: ...r case is installed 4 Run the oven and check all functions Microwave ovens should not be run empty To test for the presence of microwave energy within a cavity place a cup of cold water on the oven turntable close the door and set the power to HIGH and then set the microwave timer for two 2 minutes When the two minutes has elapsed timer at zero carefully check that the water is now hot If the wate...

Page 8: ...he water container shall be a low form of 600 ml 20 oz beaker with an inside diameter of approx 8 5 cm 3 1 2 in and made of an electrically nonconductive material such as glass or plastic The placing of this standard load in the oven is important not only to protect the oven but also to insure that any leakage is measured accurately 4 Set the cooking control on Full Power Cooking Mode 5 Close the ...

Page 9: ...rately 4 Set the cooking control on Full Power Cooking Mode 5 Close the door and select a cook cycle of several minutes If the water begins to boil before the survey is completed replace it with 275 ml of cool water C Leakage test with enclosure installed 1 Grasp probe of survey instrument and hold it perpendicular to gap between door and the body of the oven 2 Move the probe slowly not faster tha...

Page 10: ...wave Power for Variable Cooking Repetition Rate P HI Full power throughout the cooking time P 90 approx 90 of Full Power P 80 approx 80 of Full Power P 70 approx 70 of Full Power P 60 approx 60 of Full Power P 50 approx 50 of Full Power P 40 approx 40 of Full Power P 30 approx 30 of Full Power P 20 approx 20 of Full Power P 10 approx 10 of Full Power P 0 No power throughout the cooking time Sensor...

Page 11: ...adapter properly grounded and polarized If an extension cord must be used it should be a 3 wire 15 amp or more rated cord Do not drape over a countertop or table where it can be pulled on by children or tripped over accidentally Discharging Capacitor 1 High Voltage Warning Do not attempt to measure any of the high voltages this includes the filament voltage of the magnetron High voltage is present...

Page 12: ...nterclockwise 5 Oven lamp It will light when oven is operating or door is opened 6 Oven door with see through window 7 Ventilation openings Rear 8 Auto Touch control panel 9 Time display Digital display 99 minutes 99 seconds 10 Wave guide cover 11 Power supply cord NOTE Some one touch cooking features as add 30 sec are disabled after three minutes when the oven is not in use These features are aut...

Page 13: ...vity where the food is placed to be cooked 5 Upon completion of the cooking time the power transformer oven lamp etc are turned off and the generation of microwave energy is stopped The oven will revert to the OFF condition 6 When the door is opened during a cook cycle the monitor switch door sensing switch third door switch primary switch relay RY1 and secondary interlock relay are activated with...

Page 14: ...Operation 2 2 Figure 2 1 Oven Off Condition Figure 2 2 Oven Schematic Microwave Cooking Condition ...

Page 15: ...hey are activated by the latch head on the door When the door is opened the switches interrupt the power to all high voltage components except the oven lamp A cook cycle cannot take place until the door is firmly closed thereby activating all interlock switches The secondary interlock system consists of the door sensing switch and the secondary interlock relay located on the control circuit board ...

Page 16: ...n is designed to prevent damage to the magnetron if an over heated condition develops in the tube due to cooling fan failure obstructed air guide dirty or blocked air intake etc Under normal operation the C T fuse remains closed However when abnormally high temperatures are reached within the magnetron the C T fuse will open at 302 F 150 C causing the oven to shut down 1 The C T fuse blows when th...

Page 17: ...t This detector circuit is used to detect the output voltage of the absolute humidity circuit to allow the LSI to control sensor cooking of the unit When the unit is set in the sensor cooking mode 16 seconds clearing cycle occurs then the detector circuit starts to function and the LSI observes the initial voltage available at its AN1 terminal With this voltage given the switches SW1 to SW5 in the...

Page 18: ...Operation 2 6 Notes ...

Page 19: ...e outer case 2 Open the door and block it open 3 To discharge high voltage capacitor wait for 60 seconds and then short circuit the connection of the high voltage capacitor that is the connecting lead of the high voltage rectifier against the chassis with the use of an insulated screwdriver 4 Reconnect the leads to the primary of the power transformer 5 Reinstall the outer case cabinet 6 Reconnect...

Page 20: ...ut ex tremely uneven heating is produced in oven load food Oven does not cook properly when programmedforCookingPowerP 50 mode OperatesproperlyonCooking P HI HIGH mode Oven goes into COMPU DEFROST but food is not defrosted well AH sensor does not end during sensor cooking condition Oven does not shut off after a cup of water is boiling by sensor cooking Oven stops at 16 sec after starting Off Cond...

Page 21: ...carefully 1 Fill the measuring cup with 16 oz 453 cc of tap water and measure the temperature of the water with a thermometer or thermocouple temperature tester Stir the thermometer or thermo couple 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 ...

Page 22: ...s 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 HIGH VOLTAGE CAPACITOR TEST 1 Disconnect ...

Page 23: ...should indicate a closed circuit unless the tem perature of the cavity temperature fuse reaches approximately 302 F 150 C An open cavity temperature fuse indicates overheating of the oven exchange the cavity temperature fuse and check inside of oven cavity and for improper setting of cooking time or operation of control unit Check for restricted air flow through the vent holes of the oven cavity e...

Page 24: ... 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 outer case cabinet 7 Reconnect the power supply cord after the outer case is installed 8 Run the oven and check all functions ...

Page 25: ...ts of circuits including semiconductors such as LSI ICs etc Therefore unlike conventional microwave ovens proper maintenance cannot be performed with only a voltmeter and ohmmeter In this service manual the touch control panel assembly is divided into two units Control Unit and Key Unit and also the Control Unit is divided into two units LSI Unit and Power Unit and troubleshooting by unit replacem...

Page 26: ...pads produce a signal 2 2 In connection with indicators a At a certain digit all or some segments do not light up b At a certain digit brightness is low c Only one indicator does not light d The corresponding segments 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 The following s...

Page 27: ...et 8 Reconnect the power supply cord after the outer case is installed 9 Run the oven and check all functions RELAY TEST 1 Disconnect power supply cord and 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 insu...

Page 28: ...e door and block it open 3 Discharge high voltage capacitor 4 Disconnect the leads to the primary of the power transformer 5 Using an ohm meter check between the terminals as described in the following table If incorrect readings are obtained replace the noise filter 6 Reconnect all leads removed from components during testing 7 Re install the outer case cabinet 8 Reconnect the power supply cord a...

Page 29: ...arge high voltage capacitor before touching any oven components or wiring after removing outer case AVOID POSSIBLE EXPOSURE TO MICROWAVE ENERGY PLEASE FOLLOW INSTRUCTIONS BELOW BEFORE OPERATING THE OVEN 1 Disconnect the power supply cord 2 Make sure that a definite click can be heard when the microwave oven door is unlatched Hold the door in a closed position with one hand then push the door open ...

Page 30: ... two 2 screws from rear and four 4 screws along the right side of outer case 5 Slide the entire outer case back out about 1 inch 3 cm to free it from retaining clips on the cavity face plate 6 Lift entire outer case from the unit 1 Disconnect oven from power supply before removing outer case 2 Discharge the high voltage capacitor before touching any oven components or wiring Special screw Screwdri...

Page 31: ...ply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Disconnect wire leads from magnetron 5 Remove the two 2 screws holding the chassis support to the magnetron and the oven cavity front flange 6 Slide the magnetron duct slightly so that the two 2 screws at left hand side of the magnetron appear 7 Carefully remove the four 4 screws holding magn...

Page 32: ...to the control panel frame adjust the upper edge and right edge of the key unit to the correct position of control panel frame 3 Place the key unit firmly to the control panel frame by rubbing with soft cloth not to scratch Key Sheet Replacement Removal 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 Remove the co...

Page 33: ...tch 6 Reinstall the control panel frame to the oven NOTE Do not touch the contact surface of the ribbon cable edge Turntable Motor Removal 1 Disconnect the power supply cord 2 Remove turntable and turntable support from oven cavity 3 Lay the oven on it s backside Remove the turntable motor cover by snipping off the material in four corners 4 Where the corners have been snipped off bend corner area...

Page 34: ...t should be pinched with pliers Shaft Table Center of bracket Figure 4 5 Cooling Fan Motor Removal To discharge the high voltage capacitor wait for 60 seconds and then short circuit the connection of the high voltage capacitor that is the connecting lead of the high voltage rectifier against the chassis with the use of an insulated screwdriver Make sure that no metal pieces enter the gap between t...

Page 35: ...f the latch hook should be less than 0 5mm The vertical position of the latch hook should be adjusted so that the door sensing switch primary switch and third door switch are activated with the door closed The horizontal position of the latch hook should be adjusted so that the plunger of the monitor switch is pressed with the door closed 6 Secure the screws with washers firmly 7 Check the operati...

Page 36: ...install door panel to door frame by fitting twelve 12 tabs of door frame to twelve 12 holes of door panel 4 Put sealer film on door panel Refer to Sealer Film about how to handle a new one 5 Catch two 2 pins of door panel on two 2 hole of upper and lower oven hinges 6 Re install choke cover to door panel by pushing in After any service make sure of the following 1 Door latch heads smoothly catch l...

Page 37: ...ge Lower Oven Hinge Choke Cover Sealer Film Installation 1 Put the adhesive tape on the backing film of the sealer film as shown in Figure 4 9 2 Tear the backing film by pulling the adhesive tape 3 Put the pasted side of the sealer film on the door panel Figure 4 9 Door Removal Sealer Film Backing Film Adhesive Tape ...

Page 38: ...Component Teardown and Testing 4 10 Notes ...

Page 39: ...Wiring Diagrams 5 1 Wiring Diagram ...

Page 40: ...Wiring Diagrams 5 2 Oven Wiring Schematic Off Condition ...

Page 41: ...Parts List 6 1 Key Unit And Door Assembly ...

Page 42: ...Parts List 6 2 ...

Page 43: ...Parts List 6 3 Oven And Cabinet Parts ...

Page 44: ...ble items DOOR PROTECTION SHEET PLASTIC BAG PACKING CASE TOP PAD ASSEMBLY INTO THE OVEN CAVITY 47 TURNTABLE TRAY 50 OPERATION MANUAL BOTTOM PAD ASSEMBLY TRAY HOLDER 46 TURNTABLE SUPPORT ON TOP OF THE OVEN Packing And Accessories ...

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