Sharp R-420EK Service Manual Download Page 10

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R - 4 2 0 E K

Figure O-2 Oven Schematic - Cooking Condition

Figure O-1 Oven Schematic - Off Condition

SCHEMATIC

NOTE: CONDITION OF OVEN

1. DOOR CLOSED
2. CLOCK APPEARS ON DISPLAY

120V AC
60 Hz

OVEN
LAMP

TURN-
TABLE
MOTOR

FAN
MOTOR

MONITOR
SWITCH

H.V. RECTIFIER

MAGNETRON

SECONDARY
INTERLOCK
SWITCH

TTM

CAVITY
TEMP.
FUSE

COM.

N.O.

N.C.

N.O.

DOOR
SENSING
SWITCH

(RY-1)

(RY-2)

CONTROL UNIT

PRIMARY
INTERLOCK
RELAY

GRN

POWER
TRANSFORMER

MONITOR
FUSE 20A

MAGNETRON
TEMP.
FUSE

CAPACITOR 1.0µF
AC 2300V

AH SENSOR

SCHEMATIC

2. CLOCK APPEARS ON DISPLAY

3. VARIABLE COOKING CONTROL "HIGH"

2. COOKING TIME PROGRAMMED

1. DOOR CLOSED

NOTE: CONDITION OF OVEN

4. "START" PAD TOUCHED

120V AC
60 Hz

OVEN
LAMP

TURN-
TABLE
MOTOR

FAN
MOTOR

MONITOR
SWITCH

H.V. RECTIFIER

MAGNETRON

SECONDARY
INTERLOCK
SWITCH

TTM

MONITOR
FUSE 20A

CAVITY
TEMP.
FUSE

MAGNETRON
TEMP.
FUSE

COM.

N.O.

N.C.

N.O.

DOOR
SENSING
SWITCH

(RY-1)

(RY-2)

CONTROL UNIT

PRIMARY
INTERLOCK
RELAY

GRN

POWER
TRANSFORMER

CAPACITOR 1.0µF
AC 2300V

AH SENSOR

Note:* Indicates components, with potential above 250v

Summary of Contents for R-420EK

Page 1: ... POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY INSIDE FRONT COVER BEFORE SERVICING INSIDE FRONT COVER WARNING TO SERVICE PERSONNEL 1 MICROWAVE MEASUREMENT PROCEDURE 2 FOREWORD AND WARNING 3 PRODUCT SPECIFICATIONS 4 GENERAL INFORMATION 4 OPERATION 6 TROUBLESHOOTINGGUIDE 10 TESTPROCEDURE 11 TOUCHCONTROLPANEL 21 COMPONENTREPLACEMENTANDADJUSTMENTPROCEDURE 27 PICTORIALDIAGRAM 33 POWERUNITCIRCUIT 34 C...

Page 2: ...transmission systems shall be repaired replaced or adjusted by procedures described in this manual before the oven is released to the owner e A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner BEFORE SERVICING Before servicing an operative unit perform a microwave emission check as per the Microwave Me...

Page 3: ...pacitor 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 outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Reconne...

Page 4: ...enter of the oven cavity The 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...

Page 5: ...eformed or warped E There is no other visible damage with the oven Servicing and repair work must be carried out only by trained service personnel DANGER Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing Service person nel Do not contact the following parts while the appliance is energized High Voltage Capacitor Power Transformer Magn...

Page 6: ...ion Pad Timer Clock pad Minute Plus Pad Power Level Pad Stop Clear Pad Start Touch on Pad Oven Cavity Light Yes Safety Standard UL Listed FCC Authorized DHHS Rules CFR Title 21 Chapter 1 Subchapter J SPECIFICATION GENERAL INFORMATION GROUNDING INSTRUCTIONS This oven is equipped with a three prong grounding plug It must be plugged into a wall receptacle that is properly installed and grounded in ac...

Page 7: ...CES CUT OR RE MOVE THE ROUND GROUNDING PRONG FROM THIS PLUG OVEN DIAGRAM 1 One touch door open button Push to open door 2 Door latches The oven will not operate unless the door is securely closed 3 Removable turntable support 4 Removable turntable The turntable will rotate clockwise or counterclockwise 5 Oven lamp It will light when oven is operating or door is opened 6 Oven door with see through ...

Page 8: ...ntable 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 primary interlock relayandismechanicallyassociatedwiththedoorsothat it will function in the fo...

Page 9: ...e of the SENSOR pads NOTE The oven should not be operated on sensor immediately after plugging in the unit Wait two minutes before cooking on SENSOR 2 The coil of shut off relay RY 1 is energized the turntablemotorareturnedon butthepowertransformer is not turned on 3 After about 16 seconds the cook relay RY 2 is energized The power transformer is turned on microwaveenergyisproducedandfirststageiss...

Page 10: ...RANSFORMER MONITOR FUSE 20A MAGNETRON TEMP FUSE CAPACITOR 1 0µF AC 2300V AH SENSOR SCHEMATIC 2 CLOCK APPEARS ON DISPLAY 3 VARIABLE COOKING CONTROL HIGH 2 COOKING TIME PROGRAMMED 1 DOOR CLOSED NOTE CONDITION OF OVEN 4 START PAD TOUCHED 120V AC 60 Hz OVEN LAMP TURN TABLE MOTOR FAN MOTOR MONITOR SWITCH H V RECTIFIER MAGNETRON SECONDARY INTERLOCK SWITCH TTM OL FM MONITOR FUSE 20A CAVITY TEMP FUSE MAGN...

Page 11: ...BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH PRIMARY INTERLOCK RELAY RY2 RELAY RY1 SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OP ERATION REFERTOCHAPTER TESTPRO CEDURE NOTE MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY TURNTABLE MOTOR The turntable motor rotates the turntable located on the bottom of the oven cavity so that the foods on the turntable cook evenly durin...

Page 12: ... an assembly IMPORTANT Whenever troubleshooting is performed with the power supply cord disconnected It may in some cases be necessary to connect the power supply cord after the outer case has been removed in this event 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 Disconnect the leads to the primary of the powe...

Page 13: ... Oven goes into a cook cycle but extremely uneven heating is produced in oven load food Oven does not cook properly when programmed for Cooking Power 5 mode Operates properly on Cooking Power 10 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 st...

Page 14: ...E CAUTION SHOULD BE OBSERVED Power output of the magnetron can be measured by performing a water temperature rise test This test shouldonlybeusedifabovetestsdonotindicateafaultymagnetronandthereisnodefectinthefollowing componentsorwiring siliconrectifier highvoltagecapacitorandpowertransformer Thistestwillrequire a 16 ounce 453cc measuring cup and an accurate mercury thermometer or thermocouple ty...

Page 15: ...ooling fan and air guide 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 MAGNETRON TEMPERATURE FUSE TEST 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 A conti...

Page 16: ...ock 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 PRIMARY INTERLOCK SYSTEM TEST DOOR SENSING SWITCH 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 Iso...

Page 17: ...ve 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 replacement is described according to the symptoms indicated Before testing 1 Disconnect the power supply...

Page 18: ...oes not operate properly c Cooking is not possible When testing is completed 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 Reconnect all leads removed from components during testing 5 Re install the outer case cabinet 6 Reconnect the power supply cord after the outer case is installed 7 Run the oven and check al...

Page 19: ...indicate 120 volts if not check oven circuit RY1 and RY2 Relay Test These relays are operated by D C voltage Check voltage at the relay coil with a D C voltmeter during the microwave cooking operation DC voltage indicated Defective relay DC voltage not indicated Check diode which is connected to the relay coil If diode is good control unit is defective RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED CO...

Page 20: ...stalled 9 Run the oven and check all functions 2 Followthetroubleshootingguidegivenbelow ifindicatordoesnotlightupafterabovecheckandrepairs are finished 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 Disconnect the leads to the primary of the power transformer 5 Ensure that these leads remain isolated from other ...

Page 21: ...es 7 2 oz of tap water in 1000 millilitres measuring cup 3 Place the container on the center of tray in the oven cavity 4 Close the door 5 Touch REHEAT SENSOR pad once Now the oven is in the sensor cooking condition and SEN SOR REHEAT will appear in the display 6 The oven will operate for the first 16 seconds without generating microwave energy NOTE ERROR will appear if the door is opened or STOP ...

Page 22: ...lunger 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 xx xx which is remaining cooking time and the display count down 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 outer c...

Page 23: ...n the clock circuit Symbol Voltage Application VC 5V LSI IC1 4 Relay Circuit A circuit to drive the magnetron fan motor turntable motor and light the oven lamp 5 Buzzer Circuit The buzzer is responsive to signals from the LSI to emit audiblesounds keytouchsoundandcompletionsound 6 Synchronizing Signal Circuit The power source synchronizing signal is available in order to compose a basic standard t...

Page 24: ...nd off shut off relay RY1 The square waveform voltage is delivered to the RY1 driving circuit and RY2 control circuit 18 P05 OUT Terminal not used 19 P110 OUT Key strobe signal Signal applied to touch key section A pulse signal is input to ANI7 P100 P101 P102 and P103 terminal while one of G8 line keys on key matrix is touched 20 P111 OUT Key strobe signal Signal applied to touch key section A pul...

Page 25: ...sor input This input is an analog input terminal from the AH sensor circuit and connected to the A D converter built into the LSI 34 ANI6 IN Input terminal to judge the model The signal out of P116 will be input into ANI6 through G2 line on key matrix The LSI will judge the model by this signal 35 ANI7 IN Signal coming from touch key When either G13 line on key matrix is touched a corresponding si...

Page 26: ...voltage for LCD 59 VSS0 IN Power source voltage 5 0V The power source voltage to the LSI is input to VSS0 terminal Connected toVC 60 95 S0 S35 OUT Segment data signal Connected to LCD The relation between signals are as follows LSI signal Pin No LCD Segment LSI signal Pin No LCD Segment S0 60 SEG 0 S18 78 SEG 18 S1 61 SEG 1 S19 79 SEG 19 S2 62 SEG 2 S20 80 SEG 20 S3 63 SEG 3 S21 81 SEG 21 S4 64 SE...

Page 27: ...e available at its AN1 terminal With this voltage given the switches SW1 to SW5 in the LSI are turned on in such a way as to change the resistance values in parallel with R107 R111 of IC2 Changing the resistance value results in that there is the same potential at both F 3 terminal of the absolute humiditysensorandAN0terminaloftheLSI Thevoltage of AN1 terminal will indicate about 16 seconds about ...

Page 28: ... oven door being closed Connect an external power source to the power input terminal of the touch control panel then it is possible to check and repair the controls of the touch control panel it is also possible to check the sensor related controls of the touch control panel by using the dummy resistor s 3 Servicing Tools Toolsrequiredtoservicethetouchcontrolpanelassembly 1 Soldering iron 30W Itis...

Page 29: ... 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 button with the other this causes the latch leads to rise it is then possible to hear a click as the door switches operate 3 Visuallycheckthedoorandcavityfaceplatefordamage dents cracks signs of arcing et...

Page 30: ...hort one of the power transformer from the high voltage capacitor 7 Remove one 1 screw holding capacitor holder with the high voltage rectifier to the base plate 8 Disconnect rectifier terminal from capacitor High voltage rectifier assembly is now free 9 Remove capacitor holder Capacitor is now free CAUTION WHEN REPLACING HIGH VOLTAGE RECTI FIER AND HIGH VOLTAGE CAPACITOR GROUND SIDE TERMINAL OF T...

Page 31: ...h soft cloth not to scratch LSI UNIT NOTE Handle the LSI unit carefully so that there is no excessive force applied to the ribbon connection LSI unit 1 Disconnect the power supply cord 2 Removeturntableandturntablesupportfromovencavity 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 ...

Page 32: ...nstalled because the bracket may be disfigured Make sure that the fan blade rotates smooth after installation Make sure that the axis of the shaft is not slanted 5 Install the fan motor to the oven cavity back plate with the two 2 screws 6 Connect the wire leads to the fan motor referring to the pictorial diagram Side View Rear View 1 Disconnectthepowersupplycordandremoveoutercase 2 Open the door ...

Page 33: ...on of the latch Figure C 3 Latch Switch Adjustments hook pushing and pulling upper portion of door toward the oven face Both results play in the door should be less than 0 5mm 2 The door sensing switch and secondary interlock switch interrupt the circuit before the door can be opened 3 Monitor switch contacts close when door is opened 4 Re install outer case and check for microwave leakage around ...

Page 34: ...s through center of latch hole 2 Deviation of door alignment from horizontal line of cavity face plate is to be less than 1 0mm 3 Door is positioned with its face pressed toward cavity face plate 4 Check for microwave leakage around door with an approvedmicrowavesurveymeter RefertoMicrowave Measurement Procedure Note The door on a microwave oven is designed to act as an electronic seal preventing ...

Page 35: ...The neutral WHT GRY wire must be connected to the terminal with N mark on the power supply cord RED WHT RED WHT WHT ORG WHT PNK GRN GRN to Oven cavity WHT WHT RED BLK WHT WHT BLUE MARK WHT RED WHT CAVITY TEMP FUSE MAGNETRON TEMP FUSE FAN MOTOR MONITOR FUSE HOLDER RED RED WHT 1 WHT GRY WHT GRN ORG ORG CN A H N NOTE The grounding conductor of the power supply cord has been grounded by power supply c...

Page 36: ...RY1 RY2 DOOR SENSING SWITCH 12PIN LEAD WIRE HARNESS CN B NC GND NC NC VR INT VA MICRO MICRO NC CN C CN A CN D AC DOOR SENSING SWITCH BUZZER OVEN LAMP FAN MOTOR TURNTABLE MOTOR OVEN LAMP FAN MOTOR TURNTABLE MOTOR D1 4 11ES1 GND VRS1 C2 1000µ 35v SP1 J1 10G471K C 2 C 3 C 9 C 4 C 1 C 5 C 6 C 8 C 7 C11 A 2 D 1 D 3 NO NO COM COM B 2 B 1 C12 AC ...

Page 37: ...P37 S21 SEG21 SEG35 S22 S23 S24 S25 S26 S27 S28 S29 S30 S31 S32 S33 S34 S35 P83 P82 P81 P80 P25 P36 P35 P34 P33 P32 P31 P30 P103 P102 VSS1 P101 P100 VDD0 ANI7 ANI6 ANI5 ANI4 ANI3 AVREF R102 37 4kF R40 4 7k R67 15k R66 15k R65 15k R64 15k R63 15k R62 15k R61 15k R60 15k R79 270k ANI6 ANI7 P100 P101 P102 P103 R78 270k R77 270k R76 270k R75 270k R74 270k R101 75kF R100 150kF R99 300k R98 620k R10 1k ...

Page 38: ...Printed Wiring Board of Power Unit WH 1 SH B SH A 1 C3 C4 C5 R3 C2 F C1 10 D4 D2 D1 D3 J1 D9 D10 RY3 CN D D8 ZD1 VRB D U R2 R1 R6 R5 SP1 3 E B D6 D5 Q2 R4 2 6 11 P S RY2 T1 AC VRS1 5 D7 OMIF D U 9 8 7 E Q1 B 4 E RY1 AC OL TTM FM B Q3 CN C CN C CN B CN A 1 1 9 12 1 1 1 2 XA VH 2 2 ...

Page 39: ...3 1 DPWBFB098MRU0 M Control unit 1 BL 3 1A QCNCMA446DRE0 J 2 pin connector CN A 1 AC 3 1B QCNCMA275DRE0 J 2 pin connector CN B 1 AB 3 1C FW VZB146MRE0 M 12Pin wire harness CN C 1 AG C2 VCEAB31VW108M J Capacitor 1000 uF 35V 1 AF D1 4 VHD11ES1 1 J Diode 11ES1 4 AB RY1 2 RRLY B002MRE0 M Relay DU24D1 1P M 2 AH RY1 2 RRLY A113DRE0 M Relay DU24D1 1P M Interchangeable 2 AG SP1 RALM A014DRE0 J Buzzer PKM2...

Page 40: ...W VZB125MRE0 M Stop switch harnnes 1 AF 6 2 FW VZB168MRE0 M Main wire harnnes 1 AU 6 3 TLABBB007MRE0 M Cavity hole cover 1 AA 6 4 FROLPB025MRK0 M Turntable support 1 AN 6 5 NTNT A095WRE0 M Turntable tray 1 AM 6 6 TCAUAB037MRR0 M Monitor caution label 1 AA 6 7 TCAUAB038MRR0 M DHHS Screw caution label 1 AB 6 8 TINSEB269MRR0 M Operation manual 1 AD 6 9 QW QZB016MRE0 M High voltage wire A 1 AC SCREWS ...

Page 41: ...VEN AND CABINET PARTS 2 3 4 7 6 7 1 5 4 6 4 8 4 11 7 2 7 10 1 15 4 9 6 3 6 5 6 4 2 1 7 10 1 12 4 10 7 2 7 2 4 3 1 13 7 3 7 6 1 10 7 6 1 9 7 8 7 8 4 2 7 11 1 11 1 3 1 4 7 1 1 8 1 8 4 4 7 1 4 1 1 1 1 2 2 2 2 2 2 2 2 2 7 5 7 11 4 12 7 5 6 6 1 7 1 6 4 5 1 14 7 9 7 7 7 9 7 7 ...

Page 42: ... 5 1 2 3 A B C D E F G H A B C D E F G H CONTROL PANEL PARTS DOOR PARTS MISCELLANEOUS 3 4 3 3 3 6 3 5 5 1 5 1 2 5 1 1 5 3 5 4 5 5 5 2 Actual wire harness may be different from illustration 6 9 6 2 6 1 3 8 3 7 3 9 3 9 3 9 3 1 3 2 ...

Page 43: ...ORIES DOOR PROTECTION SHEET PLASTIC BAG PACKING CASE TOP PAD ASSEMBLY INTO THE OVEN CAVITY 6 5 TURNTABLE TRAY 6 4 TURNTABLE SUPPORT 6 8 OPERATION MANUAL TRAY PACK SPADPB038MRE0 BOTTOM PAD ASSEMBLY TRAY HOLDER Non replaceable items ...

Page 44: ... BY SHARP CORPORATION ALL RIGHTS RESERVED No part of this publication may be repro duced stored in retrieval systems or trans mitted in any form or by any means elec tronic mechanical photocopying recording orotherwise withoutpriorwrittenpermission of the publisher ...

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