Sharp R-480J service manual Function of Important Components

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R-480J

FUNCTION OF IMPORTANT COMPONENTS

DOOR OPEN MECHANISM

The door can be opened by pushing the door open button on the control panel. When the door open button is pushed, the latch lever is moved upward, operating the latch head. The latch head is moved upward, and released from latch hook. Now the door can be opened.

Door

 

Latch Hook

Latch

 

Heads

2nd. Interlock

 

 

Relay Control

 

Switch

 

Monitor

Switch

Switch

Lever

1st. Latch

 

 

Switch

Figure D-1. Door Open Mechanism

THERMAL CUT-OUT 145˚C (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 temperature is reached within the oven cavity, the oven thermal cut-out will open at 145˚C, causing the oven to shut down. The defective thermal cut-out must be replaced with new one.

THERMAL CUT-OUT 145˚C (MAGNETRON)

The thermal cut-out located near the magnetron is de- signed 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 thermal cut-out remains closed. However, when abnormally high temperatures are reached within the magnetron, the thermal cut-out will open at 145˚C causing the oven to shut down. The defective thermal cut-out must be replaced with new one.

1ST. LATCH SWITCH AND 2ND. INTERLOCK RE- LAY CONTROL SWITCH

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.

MONITOR SWITCH

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 1st. latch switch and 2nd. interlock relay fail to open, the fuse (F10A) blows simultaneously with closing the contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE (F10A) TEST THE 1ST. LATCH SWITCH, 2ND. INTERLOCK RELAY AND MONITOR SWITCH FOR PROPER OPERATION. (RE- FER TO CHAPTER "TEST PROCEDURE".)

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 is chan- nelled through the oven cavity to remove steam and vapours given off from the heating foods. It is then ex- hausted through the exhausting air vents at the oven cavity.

NOISE FILTER

The noise filter prevents the radio frequency interference that might flow back in the power circuit.

FUSE (F10A)

1.If the wire harness or electrical components are short- circuited, this fuse blows to prevent an electric shock or fire hazard.

2.The fuse also blows when 1st. latch switch and 2nd. interlock relay remains closed with the oven door open and when the monitor switch closes.

HIGH VOLTAGE FUSE 0.75A

The high voltage fuse blows when the high voltage rectifier or magnetron is shorted.

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Contents Table of Contents Microwave Oven Model R-480J480J Sharp Corporation OSAKA, Japan Microwave Oven480J General Important InformationProduct Specifications General InformationDescription This Appliance Must be Earthed Appearance View Touch Control PanelOperation Sequence OFF ConditionMicrowave Cooking Condition Variable CookingSensor Instant Reheat Power Output ReductionCooking Sequence Function of Important Components Troubleshooting Guide ServicingRemember to Check 3D Remember to Check 4RTest Procedure Possible Cause Defective Parts ProblemMicrowave Output Power 1 litre water load Test ProceduresProcedure Component Test Letter Magnetron Test Test Procedures Letter Component Test Power Transformer TestHigh Voltage Rectifier Assembly Test High Voltage Capacitor TestProcedure Component Test Letter Switch TestNoise Filter Test Carry OUT 3D Checks Thermal CUT-OUT TestHigh Voltage Fuse Test Touch Control Panel Assembly TestBlown Fuse F10A Carry OUT 3D Checks KEY Unit Test Relay TestCarry OUT 3D Checks Steps Occurrence Cause or Correction OmifAH Sensor Test Checking the initial sensor cooking conditionTest Procedures Letter Testing Method for AH Sensor AND/OR Control UnitChecking Control Unit Sensor Dummy Resistor CircuitReset Circuit Indicator CircuitPower Source Circuit Synchronizing Signal CircuitLSI Pin No Signal Description Signal coming from touch keySignal similar to P17 Power source voltage GND0VCommon data signal COM8 Common data signal COM7Common data signal COM6 Common data signal COM5Absolute Humidity Sensor Circuit Structure of Absolute Humidity SensorOther Precautions Touch Control Panel ServicingShapes of Electronic Components Servicing of Touch Control PanelOuter Case Removal Component Replacement and Adjustment ProcedurePower Transformer Removal Positive Lock Connector NO-CASE Type Removal HOW to RE-INSTALL the Turntable Motor CoverMagnetron Removal Turntable Motor RemovalControl Panel Assembly Removal CPU Unit and Power UnitInstallation Oven Lamp and Lamp Socket RemovalPower Supply Cord Replacement After adjustment, check the followingRear View Side ViewDoor Replacement RE-INSTALLRemoval View back side of door frameSealer Film After any service, make sure of the followingInstallation Preparation for Testing Microwave MeasurementRequirement Holaday HI Simpson 380MFigure O-1. Oven Schematic-OFF Condition Figure S-1. Pictorial Diagram High Voltage ComponentsFigure S-2. Power unitl Circuit Unit FigureS3.CPUCN C ZD1 SP1 VRB RY2CN a CN D D10 RY1 RY3 TTMParts List Packing and Accessories MiscellaneousSCREWS, Nuts and Washers Not replaceable items84-21 Control Panel Parts Door Parts Miscellaneous Copyright 2004 by Sharp Corporation ALL Rights Reserved
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