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Sharp R-21AT Service Manual

Commercial microwave oven
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See also: Operating Manual
1000 W/ R-21A T
SERVICING ................................................................................................................. INSIDE FRONT COVER
CAUTION, MICROWAVE RADIATION ............................................................................................................. 1
WARNING .......................................................................................................................................................... 1
PRODUCT SPECIFICATIONS ......................................................................................................................... 2
GENERAL INFORMATION ................................................................................................................................ 2
APPEARANCE VIEW ....................................................................................................................................... 3
OPERATION SEQUENCE ................................................................................................................................ 4
FUNCTION OF IMPORTANT COMPONENTS ................................................................................................ 5
TROUBLESHOOTING GUIDE .......................................................................................................................... 6
TEST PROCEDURE ......................................................................................................................................... 7
TOUCH CONTROL PANEL ASSEMBLY ........................................................................................................ 13
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 20
MICROWAVE MEASUREMENT .................................................................................................................... 25
WIRING DIAGRAM ......................................................................................................................................... 26
PICTORIAL DIAGRAM ................................................................................................................................... 27
CONTROL PANEL CIRCUIT ........................................................................................................................... 28
PRINTED WIRING BOARD ............................................................................................................................. 29
PARTS LIST ................................................................................................................................................... 30
SERVICE MANUAL
ON
DEF
NO. X2 CHECK
MODEL
In interests of user-safety the oven should be restored to its
original condition and only parts identical to those specified
should be used.

TABLE OF CONTENTS

SHARP CORPORATION
COMMERCIAL
MICROWAVE OVEN
R-21AT
R-21AT
SX802R21ATPKK
Page

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Summary of Contents for Sharp R-21AT

  • Page 1: Table Of Contents

    R-21AT SERVICE MANUAL SX802R21ATPKK COMMERCIAL MICROWAVE OVEN 1000 W/ R-21A T NO. X2 CHECK R-21AT MODEL In interests of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used. TABLE OF CONTENTS Page SERVICING .........................

  • Page 2: Servicing

    Sharp recommend that wherever possible fault-finding is carried out with the supply disconnected. In some cases, it may be necessary to connect the supply with the cover removed to carry out fault investigation in the circuitry.

  • Page 3: Caution Microwave Radiation

    APPEARANCE VIEW R-21AT GENERAL IMPORTANT INFORMATION OPERATING SEQUENCE This Manual has been prepared to provide Sharp Corp. Service engineers with Operation and Service Information. It is recommended that service engineers carefully study the entire text FUNCTION OF IMPORTANT of this manual, so they will be qualified to render satisfactory customer COMPONENTS service.

  • Page 4: General Information

    R-21AT PRODUCT DESCRIPTION SPECIFICATION ITEM DESCRIPTION Power Requirements 230 - 240 Volts 50 Hertz Single phase, 3 wire earthed Power Output 1000 W nominal of RF microwave energy (measured by method of IEC 705) Operating frequency 2450 MHz Case Dimensions...

  • Page 5: Appearance View

    R-21AT APPEARANCE VIEW OVEN 1. Oven light 2. Ceramic shelf 3. Control panel 4. Cavity face plate 5. Door latch openings 6. Door latches 7. Door hinges 8. Door seals and sealing surfaces 9. Door handle 10.Oven door with see-through window 11.Air ventilation cover and openings...

  • Page 6: Operation Sequence

    R-21AT OPERATION SEQUENCE OFF CONDITION 6-1. When the oven door is opened during or after the cycle of a cooking program, the 1st. interlock switch, Closing the door activates the 1st. latch switch, 2nd. latch latch switch and 2nd. interlock relay control switch switch and stop switch.

  • Page 7: Function Of Important Components

    R-21AT FUNCTION OF IMPORTANT COMPONENTS DOOR OPEN MECHANISM HIGH VOLTAGE FUSE 0.75A The door is opened by grasping the door handle, refer to The high voltage fuse blows when the high voltage rectifier Figure D-1. or the magnetron is shorted.

  • Page 8: Troubleshooting Guide

    R-21AT TROUBLESHOOTING GUIDE 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. These tests are given a procedure letter which will be found in the “Test Procedure”...

  • Page 9: Test Procedure

    R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST MAGNETRON TEST NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE THE OVEN IS IN OPERATION. CARRY OUT 3D CHECKS. Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
  • Page 10 R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Initial temperature ....................T1 = 11°C Temperature after (42 + 2) = 44 sec ..............T2 = 21°C Temperature difference Cold-Warm ..............∆T1 = 10˚C Measured output power The equation is “P = 100 x ∆T” ..........P = 100 x 10°C = 1000 Watts ±...
  • Page 11 R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST it has been charged. D. A short-circuited capacitor shows continuity all the time. E. An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ resistance. F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
  • Page 12 R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST NOISE FILTER TEST CARRY OUT 3D CHECKS. FUSE M10A DISCHARGE RESISTOR 680 kΩ Disconnect the leads from the terminals of noise filter. Using an ohmmeter, check between the terminals as described in the following table.
  • Page 13 R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST e) Wrong figure appears. f) A certain group of indicators do not light up. g) The figure of all digits flicker. 2-3 Other possible troubles caused by defective control unit. a) Buzzer does not sound or continues to sound.
  • Page 14 R-21AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD (PWB) IS OPEN To protect the electronic circuits, this model is provided with a fine foil pattern added to the input circuit on the PWB, this foil pattern acts as a fuse.

  • Page 15: Touch Control Panel Assembly

    R-21AT TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units as 11) Relay Driving Circuit shown in the touch control panel circuit. This is a circuit for driving output relay by IC1 output.
  • Page 16 R-21AT Pin No. Signal Description AN5-AN4 Terminal to change functions according to the model. Signal in accordance with the model in operation is applied to set up its function. 9-10 AN3-AN2 Terminal not used. Input signal which communicates the door open/close information to LSI.
  • Page 17 R-21AT Pin No. Signal Description RESET Auto clear terminal. Signal is input to reset the LSI to the initial state when power is supplied. Temporarily set to "L" level the moment power is supplied, at this time the LSI is reset. Thereafter set at "H"...
  • Page 18 R-21AT 2-2 Memory IC (IC2) X24C02P is a 2K-bit, serial memory, enabling CMOS to be erased/written electrically. This memory is constructed with 256 registers x 8bits, enabling individual access, read and write operations to be performed. Details of input/output signal for IC2 are as shown in the following diagram.
  • Page 19 R-21AT TOUCH CONTROL PANEL 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 20 R-21AT PROCEDURE FOR CHECKING/CLEARING 3) Practice for inputting total using times (Ex. 310000 times). SERVICE COUNTS OF MICROWAVE OVEN ... Flashing / ... 0.1sec BUZZER The following procedure enables the servicer to obtain the total using times (cook cycles) since the microwave oven...
  • Page 21 R-21AT 5) Practice for cancelling total using times and total opera- DISPLAY PAUSE tion time (user and service) and all other counter. End of each stage ... Flashing / ... 0.1sec BUZZER After 10% of total cooking time is passed...

  • Page 22: Component Replacement And Adjustment Procedure

    R-21AT COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven. 1. Disconnect the oven from power supply. 4. The door is bent or warped. 2. Visually check the door and cavity face plate for dam- 5.
  • Page 23 R-21AT 3. Remove the one (1) screw holding the air guide to the 6. Remove the magnetron from the waveguide with care magnetron and remove the air guide. so the magnetron antenna is not hit by any metal object 4. Remove the one (1) screw holding the chassis support around the antenna.

  • Page 24: Fan Motor Replacement

    R-21AT FAN MOTOR REPLACEMENT CAUTION: REMOVAL * Do not reuse the removed fan blade because the 1. CARRY OUT 3D CHECKS. hole (for shaft) may be larger than normal. 2. Remove the one (1) screw holding the noise filter to the 12.Remove the two (2) screws holding the fan motor to the...
  • Page 25 R-21AT 1ST. INTERLOCK SWITCH, LATCH SWITCH, 2ND. INTERLOCK RELAY CONTROL SWITCH, AND MONITOR SWITCH REMOVAL 1. CARRY OUT 3D CHECKS. 4. Make sure that the monitor switch is operating properly and check continuity of the monitor circuit. Refer to 2. Remove the control panel assembly referring to "CON- TROL PANEL ASSEMBLY REMOVAL".
  • Page 26 R-21AT 5. Release choke cover from door panel. RE-INSTALL OF THE DOOR 6. Now choke cover is free. 1. Re-install all door parts except the choke cover. 2. Catch two (2) pins of door panel on two (2) holes of Choke Cover upper and lower oven hinges.

  • Page 27: Microwave Measurement

    R-21AT INSTALLATION OF CERAMIC SHELF 1. Disconnect the oven from the power supply. WARNING 2. Open the oven door and wedge it open. Make sure that the rubber packing is not caught be- 3. Make sure that the smooth surface of the ceramic shelf tween the oven door and the oven cavity front plate, to face up.

  • Page 28: Wiring Diagram

    R-21AT SCHEMATIC NOTE: Indicates components with potential above 250 V. NOTE: CONDITION OF OVEN 1. DOOR CLOSED. APPEAR ON DISPLAY. THERMAL THERMAL CUT-OUT NOISE FILTER CUT-OUT 125˚C (OVEN) 145˚C (MG) 2ND. INTERLOCK RLAY CONTROL SWITCH LATCH 1ST. INTERLOCK SWITCH SWITCH...

  • Page 29: Pictorial Diagram

    R-21AT...

  • Page 30: Control Panel Circuit

    R-21AT...

  • Page 31: Printed Wiring Board

    R-21AT (C83) (C82) (C81) (C80) (R91) (R90) (JJ) (R89) (R66) (C64) (R69) (JH) (R65) (R68) (C60) (R60) (R62) (C101) (C60) (J5) (JG) (JD) (R61) (J6) (JE) (R64) (R63) (C63) (CN - H) (JA) (R1) (ZD1) (R2) (R101) (14) (15) (16)

  • Page 32: Parts List

    R-21AT 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-MA086WRE0 Monitor switch...
  • Page 33 R-21AT ∆ 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 VRS-B13AA101J Resistor 100 ohm RRLY-A092DRE0 Relay (VRB18SP) RRLY-A093DRE0 Relay (VRB18)
  • Page 34 R-21AT ∆ 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 5-19 XEPSD40P25K00 Screw : 4mm x 25mm 5-20 PCUSUA508WRP0...

  • Page 35: Oven And Cabinet Parts

    R-21AT OVEN AND CABINET PARTS 1-10 4-23 7-13 4-10 7-13 7-13 4-26 4-21 7-12 1-13 4-26 4-17 4-27 4-35 4-28 1-17 4-14 7-10 1-18 4-15 7-10 4-25 7-11 1-12 4-18 7-10 4-36 4-34 4-22 4-13 4-20 4-19 1-15 1-11 7-14...
  • Page 36 R-21AT CONTROL PANEL PARTS 3-2-3 3-2-2 DOOR PARTS 3-2-1 5-15 5-17 5-21 5-16 5-13 5-16 5-20 5-16 5-13 5-4-2 5-4-4 5-4-1 5-4-3 5-4-4 5-16 5-12 5-14 5-19 5-12 5-18 5-11 5-19 MISCELLANEOUS 5-10 Actual wire harness may be different from illustration.

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