Sharp R-875 Service Manual
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Sharp R-875 Service Manual

Microwave oven with grill and convection
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CAUTION, MICROWAVE RADIATION .................................................................................................... 2
SERVICING ............................................................................................................................................. 4
PRODUCT SPECIFICATIONS ................................................................................................................. 7
GENERAL INFORMATION ....................................................................................................................... 7
APPEARANCE VIEW .............................................................................................................................. 8
OPERATION SEQUENCE ........................................................................................................................ 9
FUNCTION OF IMPORTANT COMPONENTS ..................................................................................... 13
TROUBLESHOOTING GUIDE ............................................................................................................... 15
TEST PROCEDURE .............................................................................................................................. 16
CONTROL PANEL ASSEMBLY ............................................................................................................ 23
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE .................................................. 28
MICROWAVE MEASUREMENT ........................................................................................................... 34
TEST DATA AT A GLANCE .................................................................................................................. 34
SCHEMATIC DIAGRAMS ...................................................................................................................... 35
PICTORIAL DIAGRAM .......................................................................................................................... 39
POWER UNIT CIRCUITDIAGRAM ......................................................................................................... 40
PRINTED WIRING OF KEY AND JOG UNIT ......................................................................................... 41
CPU UNIT CIRCUITDIAGRAM ............................................................................................................... 42
PRINTED WIRING BOARDOF POWER UNIT DIAGRAM ..................................................................... 43
PRINTED WIRING OF BOARD OF JOG SWITCH UNIT DIAGRAM .................................................... 44
PARTS LIST .......................................................................................................................................... 45
EXPLODED DIAGRAM OF OVEN PARTS ........................................................................................... 48
CONTOL PANEL & DOOR PARTS DIAGRAM ..................................................................................... 49
MISCELLANEOUS/PACKING & ACCESSORIES ................................................................................. 50
SERVICE MANUAL
®
MICROWAVE OVEN WITH
GRILL AND CONVECTION
MODELS
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
R-875/885 -
R-875(B)
R-875(K)
R-875(W)
R-885(AL)
1
S70225R875EHW
Page

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  • Page 1: Table Of Contents

    PRINTED WIRING BOARDOF POWER UNIT DIAGRAM ..............43 PRINTED WIRING OF BOARD OF JOG SWITCH UNIT DIAGRAM ............ 44 PARTS LIST ............................45 EXPLODED DIAGRAM OF OVEN PARTS ................... 48 CONTOL PANEL & DOOR PARTS DIAGRAM ..................49 MISCELLANEOUS/PACKING & ACCESSORIES ................. 50 SHARP CORPORATION R-875/885 -...

  • Page 2: Caution Microwave Radiation

    Alle mikrobølgeindgange og-udgange, bølgeledere, flanger og tætningsstrimler må være forsvarligt udført. Anvend aldrig ovnen uden en mikrobølgesabsorberende anordning. Se aldrig ind i en åben bølgeleder eller antenne, mens ovnen er i brug. R-875/885 -...
  • Page 3 GENERAL IMPORTANT INFORMATION 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 of this manual, so they will be qualified to render satisfactory customer service.

  • Page 4: Servicing

    Sharp beveelt ten sterkste aan dat, voor zover mogelijk, defecten worden opgespoord wanneer de stekker uit het Wanneer alle reparaties zijn uitgevoerd en de oven weer in stopcontact is gehaald.
  • Page 5 är kallt utför Du 3 steg kontroller och kontrollerar anslutningarna till varje enskild komponent på nytt. Sharp rekommenderar att felsökning sker med strömmen fränkopplad. Ibland kan det var nödvändigt att koppla på När all service är klar och ugnen ihopskruvad skall ugnens strömmen efter det att höljet avlägsnats, utför da 3 Steg...
  • Page 6 Sharp raccomanda, nei limiti del possibile, che la ricerca dei guasti avvenga in assenza di alimentazione elettrica. In alcuni casi tuttavia, può essere necessario alimentare Dopo aver portato a termine le operazioni di manutenzione l'apparecchio dopo aver rimosso la scatola esterna.

  • Page 7: Product Specifications

    THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE: GREEN-AND-YELLOW : EARTH BLUE : NEUTRAL BROWN : LIVE As part of our policy of continuous improvement, we reserve the right to alter design and specifications without notice R-875/885 -...

  • Page 8: Appearance View

    NOTE: If the clock has been set, some one-touch cooking features such as "MINUTE PLUS" are disabled after three minutes when the oven is not used. These features are automatically enabled when the door is opened and closed or the STOP/CLEAR key is pressed. R-875/885 -...

  • Page 9: Operation Sequence

    3. The 2450 MHz microwave energy produced in the magnetron generates a wavelength of 12.24 cm. This energy is chan- nelled through the waveguide (transport channel) into the oven cavity, where the food is placed to be cooked. R-875/885 -...
  • Page 10 4. The relay RY4 is energized (if the cavity temperature is lower CONVECTION COOKING CONDITION than selected temperature) and the main supply voltage is PRE-HEATING (Figure O-4) applied to the bottom heating element. R-875/885 -...
  • Page 11 MICRO(70 - 10%)/TOP GRILL(100%) Microwave DUAL OPERATION Top heater 100% 15min, then 50% MICRO(100%)/BOTTOM GRILL(100%) Microwave 100% 20min, then 70% Bottom heater 100% 15min, then 50% DUAL OPERATION Microwave MICRO(70 - 10%)/BOTTOM GRILL(100%) Bottom heater 100% 15min, then 50% DUAL OPERATION R-875/885 -...
  • Page 12 The oven temp was checked by the thermometer when each stage is started . If the oven temp is same or higher than 105˚C, the oven was judged as "with preheating". When the oven temp is lower than 105˚C or the cooling fan stops, the oven was judged as "without preheating". R-875/885 -...

  • Page 13: Function Of Important Components

    If the wire harness or electrical components are short-circuited, this fuse F1 blows to prevent an electric shock of fire hazard. TURNTABLE MOTOR TTM The turntable motor rotates the turntable. FUSE F2 F8A 250V R-875/885 -...
  • Page 14 “Test Procedure” section. IMPORTANT: If the oven becomes inoperative because of a blown fuse F2 (F8A) in the monitored latch switch - monitor switch circuit, check the monitored latch switch and monitor switch before replacing the fuse F2 (F8A). R-875/885 -...

  • Page 15: Troubleshooting Guide

    CONVECTION FAN MOTOR FAN MOTOR TURNTABLE MOTOR THERMAL CUT-OUT 145˚C TC2 THERMAL CUT-OUT 125˚C TC1 THERMISTOR MONITOR SWITCH SW3 STOP SWITCH SW2 MONITORED LATCH SWITCH SW1 HIGH VOLTAGE CAPACITOR H.V. HARNESS H.V. RECTIFIER ASSEMBLY HIGH VOLTAGE TRANSFORMER MAGNETRON R-875/885 -...

  • Page 16: Test Procedure

    Temperature after (47 + 3) = 50 sec..............T2 = 21°C Temperature difference Cold-Warm ..............∆T1 = 10°C Measured output power The equation is “P = 90 x ∆T” ............P = 90 x 10°C = 900 Watts R-875/885 -...
  • Page 17 CARRY OUT 4R CHECKS. NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BE- CAUSE OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIREC- TIONS. R-875/885 -...
  • Page 18 An open circuit thermal cut-out (OVEN) TC2 indicates that the oven cavity has overheated, this may be due to no load operation or fire in the oven cavity. CARRY OUT 4R CHECKS. R-875/885 -...
  • Page 19 A short in the asymmetric rectifier may be occurred due to short or ground in H.V. rectifier, magnetron, high voltage transformer or H.V. wire. Check them and replace the defective parts or repair the wire harness. CARRY OUT 4R CHECKS. CAUTION: Only replace fuse F2 F8A with the correct value replacement. R-875/885 -...
  • Page 20 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. b) Clock does not operate properly. c) Cooking is not possible. d) Proper temperature measurement is not obtained. R-875/885 -...
  • Page 21 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. If the foil pattern is open, follow the troubleshooting guide given below for repair. R-875/885 -...
  • Page 22 (check primary coil resistance). If any abnormal condition is detected, re- place the defective parts. CARRY OUT 4R CHECKS. VRS1 R-875/885 -...

  • Page 23: Control Panel Assembly

    LSI. The circuit. It accompanies a very small error because it LSI uses this information to control the relay and works on commercial frequency. display units. R-875/885 -...
  • Page 24 H : GND of LSI. L (-5V) 20 msec. Tact switch strobe signal. Signal applied to tact switch section. A pulse signal is input to P51-P53 terminal while one of J-6 line tact switches on matrix is touched. R-875/885 -...
  • Page 25 10%) the signal turns to “H” level 29 sec. 25 sec. 18 sec. 14 sec. 18 sec. 36 sec. 12 sec. 20 sec. and “L” level in repetition 9 sec. 45 sec. 6 sec. 26 sec. according to the power level. R-875/885 -...
  • Page 26 Connected to LCD (Pin No. 35). COM1 Common data signal: COM2. Connected to LCD (Pin No. 34). COM0 Common data signal: COM1. Connected to LCD (Pin No. 33). 98-99 VL3-VL2 Power source voltage input terminal. Standard voltage for LCD. Terminal not used. R-875/885 -...
  • Page 27 PWB, making sure that all connections are tight. 2) Open the door and block it open. 5) Be sure to use specified components where high 3) Re-connect the leads to the primary of the power precision is required. transformer. 4) Re-install the outer case (cabinet). R-875/885 -...

  • Page 28: Component Replacement And Adjustment Procedure

    Oven lamp, Magnetron, High voltage transformer To prevent an electric shock, take the following and Oven cavity. manners. 3) Sharp edge: 1. Before wiring, Bottom plate, Oven cavity, Weveguide flange, 1) Disconnect the power supply. Chassis support and other metallic plate.
  • Page 29 8. Install the noise filter to the fan duct and the chassis CAUTION: support with the one (1) screw. • Do not reuse the removed fan blade as the 9. Re-connect the wire leads to the fan motor. R-875/885 -...
  • Page 30 4. Cut the four (4) bridges holding the turntable motor Re-install cover to the base plate with cutting pliers as shown in 1. Remove the any sharp edges on the turntable motor Figure C-1(a). cover and the base plate with the cutting pliers.
  • Page 31 3. Disconnect the wire leads from the bottom heating element to the oven cavity. element. 7. Remove the bottom heating element from the oven 4. Remove the two (2) nuts holding the heater cover and cavity . heater packing to the bottom heater. R-875/885 -...
  • Page 32 (tabs on the 3. Insert a putty knife (thickness of about 0.5mm) into the door panel assembly) to prevent microwave gap between the choke cover and door frame as shown leakage. in Figure C-7 to free engaging parts. R-875/885 -...
  • Page 33 5. Hold the door panel to the door frame with four (4) Hinge screws. 6. Located door panel hinge pins into cavity hinge loca- tion hole. Figure C-8. Door Replacement 7. Re-install choke cover to door panel by clipping into position. R-875/885 -...

  • Page 34: Microwave Measurement

    AC 2100V 1.13µF Magnetron Filament < 1Ω / Filament – chassis ∞ ohm. Filament winding < 1Ω High voltage transformer Secondary winding Approx. 124 Ω / Primary winding Approx. 1.9 Ω WARNING: DISCONNECT THE PLUG WHEN MEASURING RESISTANCE. R-875/885 -...

  • Page 35: Schematic Diagrams

    3. " . O" APPEARS ON DISPLAY. F2: FUSE F8A NOISE FILTER TC1: THERMAL CUT-OUT TC2: OVEN THERMAL SW2: THERMISTOR CUT-OUT STOP SWITCH SW3: MONITOR SW1: MONITORED LATCH SWITCH ASYMMETRIC SWITCH RECTIFIER Figure O-1(c) Oven Schematic-OFF Condition after the oven door is closed. R-875/885 -...
  • Page 36 4. STRAT BUTTON PRESSED. F2: FUSE F8A NOISE FILTER TC1: THERMAL CUT-OUT TC2: OVEN THERMAL SW2: THERMISTOR CUT-OUT STOP SWITCH SW3: MONITOR ASYMMETRIC SW1: MONITORED LATCH SWITCH SWITCH RECTIFIER Figure O-3(b) Oven Schematic-Grill cooking Condition (BOTTOM GRILL mode) R-875/885 -...
  • Page 37 6. STRAT BUTTON PRESSED. NOISE F2: FUSE F8A FILTER TC1: THERMAL CUT-OUT TC2: OVEN THERMAL SW2: THERMISTOR CUT-OUT STOP SWITCH SW3: MONITOR SW1: MONITORED LATCH SWITCH ASYMMETRIC SWITCH RECTIFIER Figure O-5(a) Oven Schematic-Dual cooking Condition (Microwave and Convection mode) R-875/885 -...
  • Page 38 5. STRAT BUTTON PRESSED. F2: FUSE F8A NOISE FILTER TC1: THERMAL CUT-OUT TC2: OVEN THERMAL SW2: THERMISTOR CUT-OUT STOP SWITCH SW3: MONITOR ASYMMETRIC SW1: MONITORED LATCH SWITCH SWITCH RECTIFIER Figure O-5(c) Oven Schematic-Dual cooking Condition (Microwave and Bottom Grill mode) R-875/885 -...

  • Page 39: Pictorial Diagram

    PICTORIAL DIAGRAM R-875/885 -...

  • Page 40: Power Unit Circuitdiagram

    TRANSFORMER KRC243M WH1-15 KTA1274 – WH1-2 STOP SWITCH WH1-1 STOP SWITCH NOTE 1. NOTE 2. : IF NOT SPECIFIED, 1/4W ± 5% WH1-n 15P WIRE HARNESS : IF NOT SPECIFIED, 0.1µF / 50V : IF NOT SPECIFIED, 1SS270A R-875/885 -...

  • Page 41: Printed Wiring Of Key And Jog Unit

    J - 5 J - 6 J - 3 SW11 ˚C J - 4 SW12 EXPRESS J - 7 SW13 SW10 AUTO WATT STOP J - 8 CN - J Figure S-3. Printed Wiring of Jog Switch Unit R-875/885 -...

  • Page 42: Cpu Unit Circuitdiagram

    CPU UNIT CIRCUIT DIAGRAM COOK SENSOR DEFROST AUTO ˚C R-875/885 -...

  • Page 43: Printed Wiring Boardof Power Unit Diagram

    PRINTED WIRING OF BOARD OF POWER UNIT DIAGRAM (J2) VRS1 POWER CONT Figure S-5. Printed Wiring Board of Power Unit R-875/885 -...

  • Page 44: Printed Wiring Of Board Of Jog Switch Unit Diagram

    PRINTED WIRING OF BOARD OF JOG SWITCH UNIT DIAGRAM SW13 SW12 DCUT SW10 SW11 Figure S-6. Printed Wiring Board of Jog Switch Unit R-875/885 -...

  • Page 45: Parts List

    CABINET PARTS 2- 1 GCABDA001URP2 Back plate 2- 2 GCABDA002URP0 Sub back plate 2- 3 GCABUW441URP0 Outer case cabinet [R-875(B)] 2- 3 GCABUW468URT0 Outer case cabinet [R-875(W)] 2- 3 GCABUW419URP0 Outer case cabinet [R-875(K)] 2- 3 GCABUW045URP0 Outer case cabinet [R-885(AL)]...
  • Page 46 Control panel [R-875(W)] 3- 8 JBTN-O016URF0 Express pizza button 3- 9 JBTN-A102URT0 Auto cook button [R-885(AL)] 3- 9 JBTN-B020URF0 Auto cook button [R-875(B)] 3- 9 JBTN-K034URF0 Auto cook button [R-875(K)] 3- 9 JBTN-W031URF0 Auto cook button [R-875(W)] 3- 10 JBTN-A103URT0...
  • Page 47 Screw: 4mm x 8mm 7- 2 LX-NZ0061WRE0 M4 Flange nut 7- 3 XWWSD50-06000 Washer: 5mm x 0.6mm 7- 4 XOTSE40P10000 Screw: 4mm x 10mm [R-875(W)][R-885(AL)] 7- 4 XOTSF40P10000 Screw: 4mm x 10mm [R-875(B)][R-875(K)] 7- 5 XHPSD40P06000 Screw: 4mm x 6mm 7- 6 XHTSD40P08RV0...

  • Page 48: Exploded Diagram Of Oven Parts

    7-14 4-11 4-23 4-17 4-10 4-22 4-13 7-18 4-12 4-15 7-19 4-31 7-18 4-20 NOTE: In the event of removing the turn- table motor cover this part should 4-29 be refitted using screw connec- 7-18 tion: LX-EZA045WRE0 (7-20) R-875/885 -...

  • Page 49: Contol Panel & Door Parts Diagram

    CONTROL PANEL AND DOOR PARTS DIAGRAM CONTROL PANEL PARTS 3-15 3-15 3-14 3-11 3-12 3-15 3-15 3-15 3-13 3-10 5-11 5-12 DOOR PARTS 5-10 5-10 R-875/885 -...

  • Page 50: Miscellaneous/Packing & Accessories

    MISCELLANEOUS/PACKING & ACCESSORIES MISCELLANEOUS Actual wire harness may be different than illustration. TOP PAD ASSEMBLY (FPADBA018URK0) PACKING AND ACCESSORIES PRINTED MATTER WRAP COVER for R-875(B)/(K)/885(AL) (SPADFA353WRE0) PROTECTION SHEET LOW RACK (SPADPA024URE0) DOOR PROTECTION SHEET HIGH RACK (SPADPA026URE0) TURNTABLE TRAY BOTTOM PAD ASSEMBLY...
  • Page 51 ® COPYRIGHT © 2002 BY SHARP CORPORATION ALL RIGHTS RESERVED. No part of this publication may be reproduced, stored in retrieval systems, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher.

This manual is also suitable for:

R-875bR-875kR-875wR-885R-885al

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