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PRECAUTIONS TO BE OBSERVED BEFORE AND
DURING SERVICING TO AVOID POSSIBLE EXPO-
SURE TO EXCESSIVE MICROWAVE ENERGY
CHAPTER 1. WARNING TO SERVICE PERSONNEL
CHAPTER 2. MICROWAVE MEASUREMENT PRO-
CEDURE
CHAPTER 3. FOREWORD AND WARNING
CHAPTER 4. PRODUCT DESCRIPTION
CHAPTER 5. GENERAL INFORMATION
CHAPTER 6. OPERATION
CHAPTER 7. TROUBLESHOOTING GUIDE
SHARP CORPORATION
SERVICE MANUAL
MODELS
In the interest of user-safety the oven should be restored to its origi-
nal condition and only parts identical to those specified should be
used.
WARNING TO SERVICE PERSONNEL: Microwave ovens con-
tain circuitry capable of producing very high voltage and cur-
rent, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Rectifier
Assembly, High Voltage Harness etc..)
CONTENTS
CHAPTER 8. TEST PROCEDURES
CHAPTER 9. TOUCH CONTROL PANEL ASSEMBLY
CHAPTER 10. PRECAUTIONS FOR USING LEAD-
FREE SOLDER
CHAPTER 11. COMPONENT REPLACEMENT AND
ADJUSTMENT PROCEDURE
CHAPTER 12. CIRCUIT DIAGRAMS
Parts List
S6603R420LPW/
MICROWAVE OVEN
R-420LK
R-420LW
This document has been published to be used
for after sales service only.
The contents are subject to change without notice.
R-420LW
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Summary of Contents for Sharp R-420LK
- Page 1 R-420LW SERVICE MANUAL S6603R420LPW/ MICROWAVE OVEN R-420LK MODELS R-420LW In the interest of user-safety the oven should be restored to its origi- nal condition and only parts identical to those specified should be used. WARNING TO SERVICE PERSONNEL: Microwave ovens con-...
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Page 2: Table Of Contents
CONTENTS PRECAUTIONS TO BE OBSERVED BEFORE AND [14] Procedure M: DEFROST TEST ....8-6 DURING SERVICING TO AVOID POSSIBLE EXPO- [15] Procedure N: FOIL PATTERN ON THE SURE TO EXCESSIVE MICROWAVE ENERGY PRINTED WIRING BOARD TEST....8-6 [16] Procedure O: AH SENSOR TEST .. -
Page 3: Precautions To Be Observed Before And During Servicing To Avoid Possible Expo
Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement Procedure outlined in this service manual. If microwave emissions level is in excess of the specified limit, contact SHARP ELECTRONICS CORPORATION immediately @1-800-237-4277. If the unit operates with the door open, service person should 1) tell the user not to operate the oven and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's Center for Devices and Radiological Health immediately. -
Page 4: When The Testing Is Completed
R420LW CHAPTER 1. R420LW WARNING TO SERVICE PERSONNEL Service Manual Microwave ovens 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 etc.. Read the Service Manual carefully and follow all instructions. -
Page 5: Chapter 2. Microwave Measurement Pro
R420LW CHAPTER 2. R420LW MICROWAVE MEASUREMENT PROCEDURE Service Manual [1] Requirements: 1. Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven should not exceed 1mW/ at any point 5cm or more from the external surface of the oven, measured prior to acquisition by a purchaser, and thereafter (through the use- ful life of the oven), 5 mW/cm at any point 5cm or more from the external surface of the oven. -
Page 6: Chapter 3. Foreword And Warning
Service Manual [1] FOREWORD This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service Information for the SHARP MICROWAVE OVEN, R-420LK and R-420LW. It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory customer service. -
Page 7: Chapter 4. Product Description
R420LW CHAPTER 4. R420LW PRODUCT DESCRIPTION Service Manual [1] SPECIFICATIONS ITEM DESCRIPTION 120 Volts Power Requirements 60 Hertz Single phase, 3 wire grounded Power Consumption 1600W / Approx. 13.5 Amperes 1100 W nominal of RF microwave energy (IEC Test procedure) Power Output Operating frequency 2450 MHz Width 21-5/8"... -
Page 8: Chapter 5. General Information Grounding Instructions
R420LW CHAPTER 5. R420LW GENERAL INFORMATION Service Manual [1] 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 accor- dance with the National Electrical Code and local codes and ordinances. In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the electric current. -
Page 9: Chapter 6. Operation Description Of Operating Se- Quence
R420LW CHAPTER 6. R420LW OPERATION Service Manual [1] DESCRIPTION OF OPERATING SEQUENCE The following is a description of component functions during oven operation. 1. OFF CONDITION 3. POWER LEVEL P-0 TO P-90 COOKING Closing the door activates the door sensing switch and primary inter- When Variable Cooking Power is programmed, the 120 volts A.C. -
Page 10: Oven Schematic
R420LW 2. The coil of shut-off relay (RY-1) is energized, the turntable motor, oven lamp and cooling fan motor are turned on, but the power AH SENSOR transformer is not turned on. 3. After about 16 seconds, the cook relay (RY-2) is energized. The power transformer is turned on, microwave energy is produced and first stage is started. -
Page 11: Description And Function Of Components
R420LW 2. Cooking Condition SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME PROGRAMMED. 3. VARIABLE COOKING CONTROL "P-HI". 4. START PAD TOUCHED. DOOR SENSING SWITCH POWER TRANSFORMER (RY2) SECONDARY INTERLOCK RELAY 120VAC 60Hz CONTROL UNIT (RY1) HIGH OVEN LAMP VOLTAGE RELAY... - Page 12 R420LW 4. 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 during cooking. The turntable may turn in either direction. 5. COOLING FAN MOTOR The cooling fan motor drives a blade which draws external cool air.
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Page 13: Chapter 7. Troubleshooting Guide
R420LW CHAPTER 7. R420LW TROUBLESHOOTING GUIDE Service Manual Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected. When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many of the possible causes of trouble will require that a specific test be performed. -
Page 14: Procedure A: Magnetron Assembly
R420LW CHAPTER 8. R420LW TEST PROCEDURES Service Manual [1] Procedure A: MAGNETRON ASSEMBLY 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. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than 1 ohm. -
Page 15: Procedure D: High Voltage Capacitor Test
R420LW 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. NOTE: Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6.3 volts. [4] Procedure D: HIGH VOLTAGE CAPACITOR TEST 1. -
Page 16: Procedure F: Secondary Interlock System Test
R420LW [7] Procedure F: SECONDARY INTERLOCK SYSTEM TEST 1. 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. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an open circuit with the door open and a closed circuit with the door closed. -
Page 17: Procedure I: Noise Filter Test
R420LW 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. [10] Procedure I: NOISE FILTER TEST 1. -
Page 18: Procedure K: Key Unit Test
R420LW f) A certain group of indicators do not light up. g) The figure of all digits flicker. 3) Other possible problems caused by defective control unit. a) Buzzer does not sound or continues to sound. b) Clock does not operate properly. c) Cooking is not possible. -
Page 19: Procedure M: Defrost Test
R420LW 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 COMPONENTS... -
Page 20: Procedure O: Ah Sensor Test
R420LW 4) Disconnect the leads to the primary of the power transformer. 5) Ensure that these leads remain isolated from other components and oven chassis by using insulation tape. 6) After that procedure, re-connect the power supply cord. 7) Follow the troubleshooting guide given below for repair. STEPS OCCURRENCE CAUSE OR CORRECTION... - Page 21 R420LW 7) Re-install the outer case (cabinet). 8) Reconnect the power supply cord after the outer case is installed. 9) Reconnect the oven to the power supply and check the sensor cook operation as follows: a) Fill approximately 200 milliliters of tap water in a 1000 milliliter measuring cup. b) Place the container on the center of tray in the oven cavity.
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Page 22: Chapter 9. Touch Control Panel Assem
R420LW CHAPTER 9. R420LW TOUCH CONTROL PANEL ASSEMBLY Service Manual [1] OUTLINE OF TOUCH CONTROL PANEL 3) Power Source Circuit This circuit generates voltages necessary in the control unit from The touch control section consists of the following units. the AC line voltage.In addition, the synchronizing signal is available (1) Key Unit in order to compose a basic standard time in the clock circuit. -
Page 23: Servicing For Touch Control Panel
R420LW Then the LSI observes that voltage at AN1 terminal and compares it with its initial value, and when the comparison rate reaches the preset value (fixed for each menu to be cooked), the LSI causes the unit to 620k stop sensor cooking;... - Page 24 R420LW 4. Other Precautions 1) Before turning on the power source of the control unit, remove the aluminium foil applied for preventing static electricity. 2) Connect the connector of the key unit to the control unit being sure that the lead wires are not twisted. 3) After aluminium foil is removed, be careful that abnormal voltage due to static electricity etc.
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Page 25: Chapter 10. Precautions For Using Lead-Free Solder
R420LW CHAPTER 10. R420LW PRECAUTIONS FOR USING LEAD-FREE SOLDER Service Manual [1] Employing lead-free solder The “Main PWB” of this model employs lead-free solder. This is indicated by the “LF” symbol printed on the PWB and in the service manual. The suffix letter indicates the alloy type of the solder. -
Page 26: Chapter 11. Component Replacement And
1. Door does not close firmly. 4. If the outer case (cabinet) is not fitted. WARNING FOR WIRING To prevent an electric shock, take the following precau- 3) Sharp edge: tions. Bottom plate, Oven cavity, Waveguide flange, 1. Before wiring, Chassis support and other metallic plate. -
Page 27: Power Transformer Removal
R420LW CAUTION: DISCONNECT OVEN FROM POWER SUPPLY BEFORE REMOVING OUTER CASE. DISCHARGE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING. NOTE: When replacing the outer case, the 2 special Torx screws must be reinstalled in the same locations. Special screw Screw Driver (Type: TORX T20 H or... -
Page 28: Oven Lamp Removal
R420LW [6] OVEN LAMP REMOVAL 1. Disconnect the power supply cord and then remove outer case. 7. Now, the oven lamp is free. 2. Open the oven door and block it open. 3. Discharge high voltage capacitor. Terminal 4. Disconnect the wire leads from the oven lamp. Oven lamp 5. -
Page 29: Turntable Motor Removal
4. Where the corners have been snipped off bend corner areas flat. 8. After replacement use the one (1) screw XOTS740P10000 to fit the No sharp edges must be evident after removal of the turntable turntable motor cover. motor cover. -
Page 30: Door Sensing Switch/Primary Interlock Switch And Monitor Switch Adjustment
R420LW [13] DOOR SENSING SWITCH/PRIMARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENT 1. Adjustment Then check lower portion of the latch hook, pushing and pulling lower portion of the door toward the oven face. Both results (play in 1. Disconnect the power supply cord, and then remove outer case. the door) should be less than 0.5mm. - Page 31 R420LW 2. Put sealer film on door panel. Refer to “Sealer Film” about how to 4. SEALER FILM handle new one. 1. Put the adhesive tape on the backing film of the sealer film as 3. Reinstall door panel to door frame by fitting nine (9) tabs of door shown in Fig.
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Page 32: Chapter 12. Circuit Diagrams
R420LW CHAPTER 12. R420LW CIRCUIT DIAGRAMS Service Manual [1] Pictorial Diagram (Figure S-1) Figure S-1. Pictorial Diagram 12 – 1... -
Page 33: Control Panel Circuit (Figure S-2)
R420LW [2] Control Panel Circuit (Figure S-2) Figure S-2. Control Panel Circuit 12 – 2... -
Page 34: Printed Wiring Board (Figure S-3)
R420LW [3] Printed Wiring Board (Figure S-3) Figure S-3. Printed Wiring Board 12 – 3... - Page 35 6-1 TURNTABLE SUPPORT INTO THE OVEN CAVITY TRAY PACK SPADFA389WRE0 PACKING CASE FPAK-A567WRKZ [R-420LW] Not replaceable items. FPAK-A568WRKZ [R-420LK] This document has been published to be used SHARP CORPORATION for after sales service only. The contents are subject to change without notice.
- Page 36 R420LW [1] OVEN PARTS 7-10 7-10 4-13 4-15 4-11 4-16 1-14 1-10 7-10 4-12 7-10 1-11 4-10 1-12 4-14 1-13 7-10 7-10...
- Page 37 Power transformer 1-13 Power transformer for production use (Interchangeable) RTRN-A745WRZZ 1-14 AH sensor assembly FDTCTA225WRKZ CABINET PARTS Outer case cabinet [R-420LW] GCABUB012WRPZ Outer case cabinet [R-420LK] GCABUA991WRPZ Base plate GDAI-A403WRWZ GLEGPA104WREZ OVEN PARTS Latch hook PHOK-A130WRFZ H.V. capacitor band LBNDKA163WRPZ...
- Page 38 R420LW [2] DOOR AND CONTROL PANEL PARTS 3-1-1 3-1-2 Actual wire harness may be different from illustration.
- Page 39 PART PARTS CODE DESCRIPTION RANK MARK RANK [2] DOOR AND CONTROL PANEL PARTS CONTROL PANEL PARTS Panel sub assembly [R-420LW] FPNLCB908WRKZ Panel sub assembly [R-420LK] FPNLCB909WRKZ 3-1-1 Key sheet [R-420LW] PSHEPB190WREZ 3-1-1 Key sheet [R-420LK] PSHEPB191WREZ 3-1-2 QSW-KA066DRZZ Open button [R-420LW]...
- Page 40 1-4-3 XOTS740P10000 1-7-10 NTNT-A108WREZ 1-6-2 COPYRIGHT © 2006 BY SHARP CORPORATION ALL RIGHTS RESERVED. No part of this publication may be reproduced, stored in retrieval systems, or transmitted in anyform or by any means, electronic, mechanical, photocopying, re- cording, or other wise, without prior written permission...