Sharp MMD24B manual Operation, Description Of Operating Sequence, Off Condition, Cooking Condition

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OPERATION

MMD24S

MMD24B

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

The following is a description of component functions dur- ing oven operation.

OFF CONDITION

Closing the drawer 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. (Page 10).

1.The display will show flashing "EnjoyYour DrawerTouch Clear and Touch Clock".

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

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 Page 10)

RELAY

CONNECTED COMPONENTS

RY-1

oven lamp/stir fan motor/fan motor

RY-2

power transformer

2.120 volts A.C. is supplied to the primary winding of the power transformer and is converted to about 3.3 volts A.C. output on the filament winding, and approximately 2370 volts A.C. 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 channelled through the waveguide into the cavity feed- box, 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 drawer is opened during a cook cycle, the monitor switch, door sensing switch, secondary interlock switch, relay (RY1) and primary interlock relay are activated with the following results.The circuits to the stir fan 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 secondary interlock switch and secondary interlock relay and is mechanically associated with the drawer so that it will function in the following sequence.

8.When the drawer opens from the closed position, the primary interlock relay (RY2) and secondary interlock switch open their contacts. And contacts of the relay (RY1) remains closed.Then the monitor switch contacts close.

9.When the drawer is closed from the open position, the monitor switch contacts open first. Then the contacts of the secondary interlock switch and door sensing switch close. And contacts of the relay (RY1) open.

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

POWER LEVEL P-0 TO P-90 COOKING

When Variable Cooking Power is programmed, the 120 volts A.C. is supplied to the power transformer intermittently through the contacts of relay (RY-2) which is operated by the control unit within a 32 second time base. Microwave power operation is as follows:

VARI-MODE

ON TIME

OFF TIME

Power 10(P-HI)

32 sec.

0 sec.

(100% power)

 

 

Power 9(P-90)

30 sec.

2 sec.

(approx. 90% power)

 

 

Power 8(P-80)

26 sec.

6 sec.

(approx. 80% power)

 

 

Power 7(P-70)

24 sec.

8 sec.

(approx. 70% power)

 

 

Power 6(P-60)

22 sec.

10 sec.

(approx. 60% power)

 

 

Power 5(P-50)

18 sec.

14 sec.

(approx. 50% power)

 

 

Power 4(P-40)

16 sec.

16 sec.

(approx. 40% power)

 

 

Power 3(P-30)

12 sec.

20 sec.

(approx. 30% power)

 

 

Power 2(P-20)

8 sec.

24 sec.

(approx. 20% power)

 

 

Power 1(P-10)

6 sec.

26 sec.

(approx. 10% power)

 

 

Power 0(P-0)

0 sec.

32 sec.

(0% power)

 

 

Note: The ON/OFF time ratio does not correspond with the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

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Contents TABLE OF CONTENTS WARNING TO SERVICE PERSONNELWARNING TO SERVICE PERSONNEL MICROWAVE MEASUREMENT PROCEDUREBEFORE SERVICING WARNING TO SERVICE PERSONNEL After repairingBefore Servicing When the testing is completedMICROWAVE MEASUREMENT PROCEDURE B. Preparation for testingA. Requirements C. Leakage testDANGER 1440 Bridge Gate Dr Diamond Bar, CASERVICE MANUAL If provided, Vent Hood, Fan assembly, Cooling Fan MotorMICROWAVE DRAWER SPECIFICATION DESCRIPTIONGENERAL INFORMATION GROUNDING INSTRUCTIONSPOWER LEVEL P-0 TO P-90 COOKING OPERATIONDESCRIPTION OF OPERATING SEQUENCE OFF CONDITIONMICROWAVE SENSOR COOKING CONDITIONCooking Sequence DOOR SCHEMATIC OFF CONDITIONCLOSED, COOK OFF CONDITTION TEST PROCEDURES PROCEDUREA TOUCH CONTROL PANEL ASSEMBLY TEST Before testingC RELAY TEST COMPONENT TESTB KEY UNIT TEST Check supply voltage and oven power cord DEFROST TESTSTEPS The rated AC voltage is not present betweenWater load cooking test TESTING METHOD FOR AH SENSOR AND/OR CONTROL UNITF AH SENSOR TEST Checking the initial sensor cooking condition CHECKING CONTROL UNIT R1, R2 22Ω ± 1% 1/2W R3 4.3kΩ ± 5% 1/4W R4 1MΩ ± 5% 1/4WRefer to the disassembly instructions found on Page G MAGNETRON ASSEMBLY TESTMICROWAVE OUTPUT POWER H THERMAL CUT-OUT TESTK MONITOR SWITCH TEST I SECONDARY INTERLOCK SWITCH TESTJ STOP SWITCH TEST M POWER TRANSFORMER TEST L BLOWN MONITOR FUSE TESTTOUCH CONTROL PANEL ASSEMBLY Control Unit and Power Unit4 Reset Circuit 5 Indicator CircuitDESCRIPTION OF LSI IC-1 Power source voltage 0V GNDInternal clock oscillation frequency setting input Power source voltage +5VSignal Segment data signalSignal coming from touch key Signal similar to P23Magnetron high-voltage circuit driving signal Common relay driving signal. Square Waveform 60HzSignal to sound buzzer Signal to synchronize LSI with commercial power source frequencyHUMIDITY SENSOR CIRCUIT ventilation opening for sensing1 Structure of Humidity Sensor 2 Operational Principle of Humidity SensorTOUCH CONTROL PANEL SERVICING 1 Servicing the touch control panel with power supply of the oven4. Other Precautions 2. Servicing of Touch Control PanelPRECAUTIONS FOR USING LEAD-FREE SOLDER 2. Using lead-free wire solder1. Employing lead-free solder 3. SolderingCOMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING FOR WIRINGWARNING AGAINST HIGH VOLTAGE To prevent an electric shock, take the following pre- cautionsMICROWAVE DRAWER DISASSEMBLY POWER CORD REPLACEMENT Un-hook/Attach Black AC Wire to Top TerminalUn-hook/Attach White AC Wire to Bottom Terminal Un-hook/Attach Ground to metal Tab on Back PlateSTOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL STOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENTRe-install After adjustment, check the followingDRAWER ASSEMBLY AND CHOKE REMOVAL DRAWER SUPPORT ANGLE REMOVALDRAWER/SLIDE RAIL REMOVAL 1. Follow the Microwave Drawer disassembly as previouslySWITCH ANGLE REMOVAL/ADJUSTMENT SWITCH ANGLE REMOVALACTUATOR REMOVAL/ADJUSTMENT Actuator adjustmentAUTO DRAWER GEAR REMOVAL/INSTALLATION Bottom coverRACK GEAR REMOVAL InstallationHIGH VOLTAGE COMPONENTS to Back PlateFigure S-2. Power Unit Circuit MICROFM A CN-AUNIT CONTROLUNIT F G HA B C D E F G H Figure S-4. Printed Wiring Board of Power Unit2.5A 5.PrintedWiringBoard UnitControlofCOPYRIGHT 2008 BY DACOR, INC ALL RIGHTS RESERVED