Sharp MMD24S, MMD24B manual Warning To Service Personnel, Before Servicing, After repairing

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WARNING TO SERVICE PERSONNEL

MMD24S

MMD24B

WARNING TO SERVICE PERSONNEL

Microwave Oven units contain circuitry capable of producing very high voltage and current, contact with following parts may result in a severe, possibly fatal, electrical shock.

(Example)

High Voltage Capacitor, High Voltage Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness, Heating Elements, etc..

Read the Service Manual carefully and follow all instructions.

Before Servicing

1.Disconnect the power supply cord Before ServicingWhen the testing is completed, , and then remove cabinet.

2.Open the drawer and keep it open.

3.Discharge high voltage capacitor.

WARNING: RISK OF ELECTRIC SHOCK. DISCHARGE THE HIGH-VOLTAGE CAPACITOR BEFORE SERVICING.

The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. 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.

Whenever troubleshooting is performed the power supply must be disconnected. It may, in some cases, be necessary to connect the power supply after the outer case has been removed, in this event:

1.Disconnect the power supply cord, and then remove neccessary covers.

2.Open the drawer and keep it open.

3.Discharge high voltage capacitor.

4.Disconnect the leads to the primary of the power transformer.

5.Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.

6.After that procedure, reconnect the power supply cord.

When the testing is completed,

1.Disconnect the power supply cord, and then remove covers.

2.Open the drawer and keep it open.

3.Discharge high voltage capacitor.

4.Reconnect the leads to the primary of the power transformer.

5.Reinstall the covers.

6.Reconnect the power supply cord.

7.Run the unit and check all functions.

After repairing

1.Reconnect all leads removed from components during testing.

2.Reinstall the covers.

3.Reconnect the power supply cord.

4.Run the oven and check all functions.

Microwave ovens should not be operated empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven tray, close the drawer and set the power to HIGH and 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 water remains cold carry out Before Servicing procedure and re-examine the connections to the component being tested.

When all service work is completed and the oven is fully assembled, the microwave power output should be checked and a microwave leakage test should be carried out.

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Contents MICROWAVE MEASUREMENT PROCEDURE TABLE OF CONTENTSWARNING TO SERVICE PERSONNEL WARNING TO SERVICE PERSONNELBEFORE SERVICING When the testing is completed WARNING TO SERVICE PERSONNELAfter repairing Before ServicingC. Leakage test MICROWAVE MEASUREMENT PROCEDUREB. Preparation for testing A. RequirementsIf provided, Vent Hood, Fan assembly, Cooling Fan Motor DANGER1440 Bridge Gate Dr Diamond Bar, CA SERVICE MANUALDESCRIPTION MICROWAVE DRAWER SPECIFICATIONGROUNDING INSTRUCTIONS GENERAL INFORMATIONOFF CONDITION POWER LEVEL P-0 TO P-90 COOKINGOPERATION DESCRIPTION OF OPERATING SEQUENCESENSOR COOKING CONDITION Cooking SequenceMICROWAVE SCHEMATIC OFF CONDITION CLOSED, COOK OFF CONDITTIONDOOR Before testing TEST PROCEDURESPROCEDURE A TOUCH CONTROL PANEL ASSEMBLY TESTCOMPONENT TEST B KEY UNIT TESTC RELAY TEST The rated AC voltage is not present between Check supply voltage and oven power cordDEFROST TEST STEPSTESTING METHOD FOR AH SENSOR AND/OR CONTROL UNIT F AH SENSOR TEST Checking the initial sensor cooking conditionWater load cooking test R1, R2 22Ω ± 1% 1/2W R3 4.3kΩ ± 5% 1/4W R4 1MΩ ± 5% 1/4W CHECKING CONTROL UNITH THERMAL CUT-OUT TEST Refer to the disassembly instructions found on PageG MAGNETRON ASSEMBLY TEST MICROWAVE OUTPUT POWERI SECONDARY INTERLOCK SWITCH TEST J STOP SWITCH TESTK MONITOR SWITCH TEST L BLOWN MONITOR FUSE TEST M POWER TRANSFORMER TEST5 Indicator Circuit TOUCH CONTROL PANEL ASSEMBLYControl Unit and Power Unit 4 Reset CircuitPower source voltage +5V DESCRIPTION OF LSI IC-1Power source voltage 0V GND Internal clock oscillation frequency setting inputSignal similar to P23 SignalSegment data signal Signal coming from touch keySignal to synchronize LSI with commercial power source frequency Magnetron high-voltage circuit driving signalCommon relay driving signal. Square Waveform 60Hz Signal to sound buzzer2 Operational Principle of Humidity Sensor HUMIDITY SENSOR CIRCUITventilation opening for sensing 1 Structure of Humidity Sensor2. Servicing of Touch Control Panel TOUCH CONTROL PANEL SERVICING1 Servicing the touch control panel with power supply of the oven 4. Other Precautions3. Soldering PRECAUTIONS FOR USING LEAD-FREE SOLDER2. Using lead-free wire solder 1. Employing lead-free solderTo prevent an electric shock, take the following pre- cautions COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDUREWARNING FOR WIRING WARNING AGAINST HIGH VOLTAGEMICROWAVE DRAWER DISASSEMBLY Un-hook/Attach Ground to metal Tab on Back Plate POWER CORD REPLACEMENTUn-hook/Attach Black AC Wire to Top Terminal Un-hook/Attach White AC Wire to Bottom TerminalAfter adjustment, check the following STOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVALSTOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENT Re-install1. Follow the Microwave Drawer disassembly as previously DRAWER ASSEMBLY AND CHOKE REMOVALDRAWER SUPPORT ANGLE REMOVAL DRAWER/SLIDE RAIL REMOVALActuator adjustment SWITCH ANGLE REMOVAL/ADJUSTMENTSWITCH ANGLE REMOVAL ACTUATOR REMOVAL/ADJUSTMENTInstallation AUTO DRAWER GEAR REMOVAL/INSTALLATIONBottom cover RACK GEAR REMOVALto Back Plate HIGH VOLTAGE COMPONENTSCN-A Figure S-2. Power Unit CircuitMICRO FM AF G H UNITCONTROL UNITFigure S-4. Printed Wiring Board of Power Unit 2.5AA B C D E F G H UnitControlof 5.PrintedWiringBoardCOPYRIGHT 2008 BY DACOR, INC ALL RIGHTS RESERVED
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