Sharp R-300BW Service Manual
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Sharp R-300BW Service Manual

Sharp R-300BW Service Manual

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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
TROUBLESHOOTING GUIDE .............................................................................................................................. 9
TEST PROCEDURE ............................................................................................................................................ 10
CONTROL PANEL ............................................................................................................................................... 17
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................ 21
PICTORIAL DIAGRAM ........................................................................................................................................ 27
CONTROL PANEL CIRCUIT ............................................................................................................................... 28
PRINTED WIRING BOARD ................................................................................................................................. 29
PARTS LIST ........................................................................................................................................................ 30
PACKING AND ACCESSORIES ......................................................................................................................... 32
SHARP CORPORATION
SERVICE MANUAL
MODEL
COOKI NG CONTR OL
DEFROST
MED
MED LOW
MED HIGH
LOW
HIGH
2
3
1
4
5
6
0
7
8
9
10
30
11
25
12
20
13
15
14
In the interest of user-safety the oven should be restored to its original
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
current, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Recti-
fier Assembly, High Voltage Harness etc..)

TABLE OF CONTENTS

MICROWAVE OVEN
R-300BW
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-300BW
S5811R300BPW/
Page

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  • Page 1: Table Of Contents

    R-300BW SERVICE MANUAL S5811R300BPW/ MICROWAVE OVEN R-300BW MODEL COOKI NG CONTR OL DEFROST MED LOW MED HIGH HIGH In the interest of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used.

  • Page 2: Precautions To Be Observed Before And During Servicing To Avoid Possible Exposure To Excessive Microwave Energy

    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 3: Warning To Service Personnel

    R-300BW WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of pro- ducing 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 Trans- former, Magnetron, High Voltage Rectifier Assem- bly, High Voltage Harness etc..

  • Page 4: Microwave Measurement Procedure

    R-300BW MICROWAVE MEASUREMENT PROCEDURE A. Requirements: 1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven should not exceed 1mW/cm at any point 5cm or more from the external surface of the oven, measured prior to acquisition...
  • Page 5 MICROWAVE OVEN R-300BW GENERAL INFORMATION FOREWORD This Manual has been prepared to provide Sharp Electronics Corp. OPERATION Service Personnel with Operation and Service Information for the SHARP MICROWAVE OVEN, R-300BW. It is recommended that service personnel carefully study the entire...

  • Page 6: General Information

    R-300BW SPECIFICATION ITEM DESCRIPTION Power Requirements 120 Volts / 12 Amperes 60 Hertz Single phase, 3 wire grounded Power Output 900 watts (IEC-705 TEST PROCEDURE) Operating frequency of 2450MHz Case Dimensions Width 20-1/2" Height 11-7/8" Depth 15-7/8" Cooking Cavity Dimensions Width 13-3/4"...
  • Page 7 R-300BW OVEN DIAGRAM 5. Oven lamp. 1. One touch door open button. It will light when oven is operating or door is Push to open door. opened. 2. Door latches. 6. Oven door with see-through window. The oven will not operate unless the 7.

  • Page 8: Operation

    R-300BW OPERATION DESCRIPTION OF OPERATING SEQUENCE The following is a description of component functions during (2) When the door is closed from the open position, the oven operation. monitor switch contacts open first. Then the contacts of the secondary interlock switch and door sensing switch OFF CONDITION close.
  • Page 9 R-300BW SCHEMATIC NOTE: CONDITION OF OVEN 1. LIGHT UP DIAL OFF. 2. DOOR CLOSED. THERMAL MONITOR THERMAL CUT-OUT (OVEN) FUSE 15A CUT-OUT (MG.) COM. POWER N.O. TRANSFORMER (RY-1) (RY-2) PRIMARY INTERLOCK RELAY CONTROL UNIT 120V AC DOOR 60 Hz SENSING...
  • Page 10 R-300BW DESCRIPTION AND FUNCTION OF COMPONENTS DOOR OPEN MECHANISM (RY2) and secondary interlock switch contacts fail to open, the monitor fuse blows simultaneously with closing The door is opened by pushing the open button on the of the monitor switch contacts.

  • Page 11: Troubleshooting Guide

    R-300BW TROUBLESHOOTING GUIDE 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 12: Test Procedure

    R-300BW CK = Check / RE = Replace RE RE A B C D E F F G H RE RE CK I CKCK J K TEST PROCEDURE PROBLEM CONDITION Home fuse or circuit breaker blows when power cord is plugged into wall receptacle...
  • Page 13 R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 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 14 R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER (HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE.) HIGH VOLTAGE RECTIFIER TEST 1. Disconnect the power supply cord, and then remove outer case.
  • Page 15 R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 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.

  • Page 16: Control Panel

    R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER with the door opened (in this condition the plunger of the monitor switch is pushed in), the meter should indicate an open circuit. If improper operation is indicated, the switch may be defective. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM) terminal and check the continuity of the monitor circuit.
  • Page 17 R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER c) Only one LED does not light up. d) All or some LEDs continue to light up. e) A certain group of LEDs do not light up. f) The LEDs flicker. 1-2 Other possible troubles caused by defective control unit.
  • Page 18 R-300BW TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 2) Open the door and block it open. 3) Discharge high voltage capacitor. 4) Follow the troubleshooting guide given below for repair. STEPS OCCURRENCE CAUSE OR CORRECTION Only pattern at "a" is broken.
  • Page 19 R-300BW CONTROL PANEL ASSEMBLY OUTLINE OF CONTROL PANEL 5) Buzzer Circuit Control Unit The buzzer is responsive to signals from the LSI to emit Control unit consists of LSI, power source circuit, synchro- audible sounds (key touch sound and completion sound).
  • Page 20 R-300BW DESCRIPTION OF LSI LSI(IZA882DR) The I/O signal of the LSI(IZA882DR) are detailed in the following table. Pin No. Signal Description Auto clear terminal. Signal is input to reset the LSI to the initial state when power is applied. Temporarily set to "L"...
  • Page 21 R-300BW Pin No. Signal Description ON/OFF time ratio in Micro Magnetron high-voltage circuit driving signal. cooking (a. 32second time base) To turn on and off the cook relay (RY2). In 100% POWER operation, the signals hold "L" level MICRO during microwave cooking and "H" level while COOK not cooking.
  • Page 22 R-300BW SERVICING 1. Precautions for Handling Electronic Components transformer. This unit uses CMOS LSI in the integral part of the 4) Re-install the outer case (cabinet). circuits. When handling these parts, the following 5) Re-connect the power supply cord after the outer precautions should be strictly followed.

  • Page 23: Component Replacement And Adjustment Procedure

    4. If the outer case (cabinet) is not fitted. WARNING FOR WIRING To prevent an electric shock, take the following pre- 3) Sharp edge: cautions. Bottom plate, Oven cavity, Waveguide flange, 1. Before wiring, Chassis support and other metallic plate.

  • Page 24: Pictorial Diagram

    R-300BW CAUTION: 1. DISCONNECT OVEN FROM POWER SUP PLY BEFORE REMOVING OUTER CASE. 2. DISCHARGE THE HIGH VOLTAGE CA- PACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING. Special screw NOTE: When replacing the outer case, the 2 special Torx screws must be reinstalled in the same locations.
  • Page 25 R-300BW MAGNETRON REMOVAL Removal 4. Reconnect the wire leads to the magnetron. Refer to 1. Disconnect the power supply cord and remove outer case. "PICTORIAL DIAGRAM" on page 27. 2. Open the door and block it open. 5. Re-install outer case and check that the oven is operating 3.
  • Page 26 4. Where the corners have been snipped off bend corner 7. Now the turntable motor is free. areas flat. No sharp edges must be evident after removal 8. After replacement use the one (1) screw to fit the of the turntable motor cover.
  • Page 27 R-300BW DOOR SENSING SWITCH/SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL Re-install 1. Disconnect the power supply cord and remove outer case. 2. Open the door and block it open. 1. Re-install each switch in its place. The secondary interlock/monitor switches are in the lower position and 3.
  • Page 28 R-300BW 9. Release door panel from seven (7) tabs of door frame by Upper oven hinge sliding door panel downward. 10.Now, door panel with sealer film is free. 11.Tear sealer film from door panel. 12.Now, door panel is free. 13.Slide latch head upward and remove it from door frame...
  • Page 29 R-300BW...
  • Page 30 R-300BW...

  • Page 31: Printed Wiring Board

    R-300BW LD10 LD11 LD12 LD13 LD14 LD15 LD16 LD18 LD24 LD17 LD23 LD22 LD19 LD21 LD20 (JA) (JD) WH - A WH - A (J1) Figure S-3. Printed Wiring Board...

  • Page 32: Parts List

    R-300BW PARTS LIST ∆ Note: The parts marked “ ” may cause undue microwave exposure. The parts marked “*” are used in voltage more than 250V. REF. NO. PART NO. DESCRIPTION Q'TY CODE ELECTRIC PARTS 1- 1 QSW-MA110WRE0 2nd interlock switch / door sensing switch...
  • Page 33 R-300BW REF. NO. PART NO. DESCRIPTION Q'TY CODE R62-63 VRD-B12EF104J Resistor 100k ohm 1/4W RRLY-A111DRE0 Relay (JV12S-KT) RRLY-A097DRE0 Relay (DU12D1-1P(M)) RALM-A014DRE0 Buzzer (PKM22EPT-THAI) RVR-BA018WRE0 Rotary encoder RTRNPA126DRE0 Transformer RVR-BA014DRE0 Potentiometer VRS1 RH-VZA032DRE0 Varistor (10G471K) VHEHZ6A3///-1 Zener diode (HZ6A3) VHEHZ4A2///-1 Zener diode (HZ4A2)
  • Page 34 1. MODEL NUMBER 2. REF. NO. 3. PART NO. 4. DESCRIPTION Order Parts from the authorized SHARP parts Distributor for your area. Defective parts requiring return should be returned as indicated in the Service Policy. 3-10 CONTROL PANEL PARTS 3-10...
  • Page 35 R-300BW OVEN AND CABINET PARTS 1-11 1-10 4-10 6-11 6-11 1-13 4-17 4-16 6-10 4-15 4-12 4-14 1-12 4-11 1-14 4-13...

  • Page 36: Packing And Accessories

    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, record- ing, or otherwise, without prior written per- mission of the publisher. '98 SHARP CORP. (5S2.530E) Printed in U.S.A...

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