Sharp MMD24S, MMD24B manual Test Procedures, Component Test, Letter, Checking Control Unit

Page 15
CHECKING CONTROL UNIT

MMD24S

MMD24B

TEST PROCEDURES

PROCEDURE

COMPONENT TEST

LETTER

 

9-2. Place the container on the center of tray in the oven cavity.

9-3. Close the drawer.

9-4. Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads 1 once and the number pad 4 once.

9-5. The control panel is in automatic Sensor operation.

9-6. The oven turns off automatically, and the time for detecting moisture will be displayed.

If new sensor does not operate properly, the problem is with the control unit, and refer to explanation be- low.

CHECKING CONTROL UNIT

(1)Disconnect the power supply cord, and then disassemble as per "MICROWAVE DRAWER DISASSEMBLY" page 27.

(2)Open the drawer and block it open.

(3)Discharge high voltage capacitor.

(4)Disconnect the sensor connector that is mounted to control panel.

(5)Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel.

(6)Disconnect the leads to the primary of the power transformer.

(7)Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

(8)After that procedure, re-connect the power supply cord.

(9)Check the sensor cook operation proceed as follows:

9-1. Close the door. Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads 1 once and the number pad 4 once.

9-2. The control panel is in the sensor cooking operation.

9-3. After approximately 25 seconds, push plunger of select switch for more than 3 seconds.This condition is same as judgement by AH sensor.

9-4. After approximately 3 seconds, the display shows “ X X . X X “ which is the time for detecting moisture.

If the above is not the case, the control unit is probably defective. If the above is proper, the AH sensor is probably defective.

(10)Disconnect the power supply cord, and then remove covers.

(11)Open the drawer and block it open.

(12)Discharge high voltage capacitor.

(13)Disconnect the dummy resistor circuit from the sensor connector of control panel.

(14)Carry out necessary repair.

(15)Reconnect all leads removed from components during testing and repairing.

(16)Re-install the covers.

(17)Reconnect the power supply cord after the outer case is installed. Run the oven and check all functions.

(18) Carry out "Water load cooking test" again and ensure that the oven works properly.

R1, R2 : 22Ω ± 1% 1/2W

R3 : 4.3kΩ ± 5% 1/4W

R4 : 1MΩ ± 5% 1/4W

R1, R2 : 22Ω ± 1% 1/2W Plunger

NC

NO

 

To connector (F)

 

 

 

COM

 

on Control Unit.

 

 

 

 

 

 

 

 

F-1

1

 

 

 

NO

2

 

 

COM

F-2

R1

 

 

3

 

 

 

 

 

 

 

 

F-3

 

R2

R3

R4

NC

 

CONNECTOR

 

 

 

 

 

 

15

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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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