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Sharp R-1750 Service Manual
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Sharp R-1750 Service Manual

Over the range microwave oven
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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 contain circuitry capable of producing very high voltage
and current. Contact with the following parts may result in a severe, possibly fatal, electrical shock. (Inverter unit
that includes High Voltage Capacitor, High Voltage Power Transformer, High Voltage Rectifier and Heat sink etc.,
and Magnetron, High Voltage Harness etc..)
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 ............................................................................................................................ 14
TEST PROCEDURE ............................................................................................................................................ 16
TOUCH CONTROL PANEL ASSEMBLY ............................................................................................................ 27
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................ 33
PICTORIAL DIAGRAM ........................................................................................................................................ 41
POWER UNIT CIRCUIT ...................................................................................................................................... 42
LSI UNIT CIRCUIT ............................................................................................................................................... 43
PRINTED WIRING BOARD ................................................................................................................................. 44
PARTS LIST ........................................................................................................................................................ 45
PACKING AND ACCESSORIES ......................................................................................................................... 50
SERVICE MANUAL
MODELS
ONE TOUCH
SENSOR
12 : 45
PM
Reheat
3
1
2
Popcoon
5
6
4
Baked
9
7
8
Potatoes
Minute
Kitchen
0
Timer
Plus +
Beverage
Center
T O U C H
S C R E E N
Keep
Warm
MINUTE
STOP/
START
PLUS
CLEAR
Defrost
6x6 NO GUESS COOKING
3+6
6 Categories + 36 Foods
Meats
Vegetables
Poultry
MORE
FROM YOUR
MICROWAVE
Fish/
Frozen
Pasta
6 x 6
Seafood
Food
Grains
Fan
Light
Turntable
Options
Options
Set Up
On/Off

TABLE OF CONTENTS

OVER THE RANGE
MICROWAVE OVEN
R-1750
R-1751
R-1752
R-1754
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-1750
R-1751
R-1752
R-1754
S8019R1750X//
Page

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  • Page 1: Table Of Contents

    R-1750 R-1751 R-1752 R-1754 SERVICE MANUAL S8019R1750X// OVER THE RANGE MICROWAVE OVEN R-1750 MODELS ONE TOUCH SENSOR 12 : 45 Reheat Popcoon Baked Potatoes R-1751 Minute Kitchen Timer Plus + Beverage Center T O U C H S C R E E N...

  • 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 Measure- ment 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-1750 R-1751 R-1752 R-1754 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) Inverter unit that includes High Voltage Capacitor, High Voltage Power Transformer, High Voltage Rectifier, Heat sink etc., and Magnetron, High...

  • Page 4: Microwave Measurement Procedure

    R-1750 R-1751 R-1752 R-1754 SERVICING FOR INVERTER UNIT WARNING This inverter unit contains circuitry capable of producing high voltage and high current. Contact with any part of the high voltage will result in electrocution. DO NOT ACCESS ANY PARTS OF INVERTER UNIT WITH POWER SUPPLY CONNECTED.

  • Page 5: Foreword And Warning

    MICROWAVE OVEN R-1750 / R-1751 / R-1752 / R-1754 GENERAL INFORMATION FOREWORD This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service Information for the OPERATION SHARP OVER THE RANGE MICROWAVE OVEN, R-1750, R-1751, R-1752, R-1754.

  • Page 6: Product Specifications

    R-1750 R-1751 R-1752 R-1754 PRODUCT SPECIFICATION ITEM DESCRIPTION Power Requirements 120 Volts / 14 Amperes / 1600 W 60 Hertz Single phase, 3 wire grounded Power Output 1100 watts (IEC TEST PROCEDURE) Operating frequency of 2450MHz Case Dimensions Width 29-15/16"...

  • Page 7: Oven Diagram

    R-1750 R-1751 R-1752 R-1754 Electrical Requirements The oven is equipped with a 3-prong grounding plug. DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE GROUNDING PIN FROM THE PLUG. The power supply cord and plug must be connected to a separate 120 Volt AC, 60 Hz, 15 Amp. or more dedicated line, using a grounded receptacle.

  • Page 8: Operation

    R-1750 R-1751 R-1752 R-1754 CONTROL PANEL ONE TOUCH SENSOR See note. 12 : 45 Reheat Popcoon Baked See note. Potatoes Minute Kitchen Plus + Timer Beverage Center T O U C H S C R E E N Keep Warm...
  • Page 9 R-1750 R-1751 R-1752 R-1754 1. The contacts of relays are closed and components programmed at the ratio of ON time and OFF time within 32 connected to the relays are turned on as follows. sec./ cycle time base. (For details, refer to Figure O-2) CONNECTION BETWEEN POWER SETTING AND ON/ OFF TIME OF INVERTER UNIT.
  • Page 10 R-1750 R-1751 R-1752 R-1754 3. Sensor detects moisture and humidity and calculates : AIR FLOW cooking time and variable power. TO DUCT TO DUCT HOOD FAN MOTOR Cooking Sequence. 1. Operate the oven in sensor cooking mode by referring to the operation manual.
  • Page 11 R-1750 R-1751 R-1752 R-1754 Wave-form of main parts are shown in Figure A-2. being destroyed. After approx. 60 millisecond, it starts During off-time, flyback voltage appears on the primary generating the driving signal from the minimum pulse width winding of the high voltage transformer. The off-time de-...
  • Page 12 R-1750 R-1751 R-1752 R-1754 SCHEMATIC OVEN MAGNETRON THERMAL CUT-OUT TEMPERATURE FUSE NOTE: CONDITION OF OVEN 1. DOOR CLOSED COM. CONTROL UNIT 2. CLOCK APPEARS ON DISPLAY FUSE HOOD FAN THERMAL High CUT OUT N.C. STOP SWITCH HOOD 120 V AC.
  • Page 13 R-1750 R-1751 R-1752 R-1754 MAGNETRON ZD70 (H.V.RESISTOR) 1000p/ 120M 100K R103 2800V 3100V 0.03 0.06 ZD40 100p 580V (ZD50) 300F VRS3 1.3KF 200V 1.5K 4.7K 220p ZD33 ZD32 1/2W ZD31 1.2K (IZA406DR) LR38166 1000p 120K 4.7K 1000p (J2) ZD30 4.7K CN-A Figure O-3.
  • Page 14 R-1750 R-1751 R-1752 R-1754 BLUE ZD50 ZD30 ZD70 VRS4 SOLDER DANGER H.V. Figure O-4. Printed Wiring Board for Inverter Unit Circuit...
  • Page 15 R-1750 R-1751 R-1752 R-1754 DESCRIPTION AND FUNCTION OF COMPONENTS DOOR OPEN MECHANISM LOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION. (REFER TO CHAP- The door is opened by pulling the door handle, refer to the TER "TEST PROCEDURE"). Figure D-1.

  • Page 16: Troubleshooting Guide

    R-1750 R-1751 R-1752 R-1754 STIRRER MOTOR HOOD LAMP The stirrer motor drives the stirrer fan to stir the microwave The hood lamps are mounted at the hood lamp angle on the radiation from the waveguide. base cover. The hood lamps can be turned off and on by touching the Light Options pad.
  • Page 17 R-1750 R-1751 R-1752 R-1754 CK = Check / RE = Replace CK LOW VOLTAGE CK NO POWER AT OUTLET RE SHORTED IN POWER CORD CK OPENED OR SHORTED WIRING CK HOOD MOTOR CAPACITOR RE HOOD LAMP OR SOCKET CK TURNTABLE OFF CONDITION...

  • Page 18: Test Procedure

    R-1750 R-1751 R-1752 R-1754 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. To discharge high voltage capacitor, wait for 60 seconds.
  • Page 19 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER Chart for checking the defective inverter unit Varistor VRS2 is defective. No power at full power output cooking Exchange the defective parts. When a foil pattern at "e" is broken, insert a jumper Varistor VRS2 or/and foil pattern open wire at "J2"...
  • Page 20 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER Description of main parts SYMBOL PART NAME FUNCTION C11, C12 High voltage capacitor High voltage capacitor for doubler circuit. Film capacitor To smooth line ripple Film capacitor Capacitor for resonant...
  • Page 21 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 4. Transistor Q2 and Q3 Check the resistance of transistor Q2 and Q3 by using ohmmeter as shown in Fig- OK: Normal ure B-5. NG: Defect The resistance between B and E of tran-...
  • Page 22 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER PRIMARY INTERLOCK SWITCH AND SECONDARY INTERLOCK SWITCH TEST 1. Disconnect the power supply cord, and then remove outer case. 2. Open the door and block it open. 3. To discharge high voltage capacitor, wait for 60 seconds.
  • Page 23 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 3. To discharge high voltage capacitor, wait for 60 seconds. 4. If the monitor fuse is blown when the door is opened, check the primary interlock switch, secondary interlock switch and monitor switch according to the "TEST PROCEDURE" for those switches before replacing the blown monitor fuse.
  • Page 24 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER TOUCH CONTROL PANEL ASSEMBLY TEST The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter.
  • Page 25 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 1) Disconnect the power supply cord, and then remove outer case. 2) Open the door and block it open. 3) To discharge high voltage capacitor, wait for 60 seconds. 4) Reconnect all leads removed from components during testing.
  • Page 26 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 9. Open the door and block it open. 10.To discharge high voltage capacitor, wait for 60 seconds. 11.Reconnect all leads removed from components during testing. 12.Re-install the outer case (cabinet).
  • Page 27 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 6) After that procedure, re-connect the power supply cord. 7) Follow the troubleshooting guide given below for repair. STEPS OCCURRENCE CAUSE OR CORRECTION The rated AC voltage is not present between Pin No.
  • Page 28 R-1750 R-1751 R-1752 R-1754 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER (4) Remove the AH sensor. (5) Install the new AH sensor. (6) Reconnect all leads removed from components during testing. (7) Re-install the outer case (cabinet). (8) Reconnect the power supply cord after the outer case is installed.

  • Page 29: Touch Control Panel Assembly

    R-1750 R-1751 R-1752 R-1754 TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units. In addition, the synchronizing signal is available in order to compose a basic standard time in the clock circuit.

  • Page 30: Description Of Lsi

    R-1750 R-1751 R-1752 R-1754 DESCRIPTION OF LSI LSI(IZA958DR) The I/O signal of the LSI(IZA958DR) is detailed in the following table. Pin No. Signal Description TIOCA2 Power level data output signal for inverter unit. 16.7 msec. H : +5V The power level will be decided by the time ratio of T1 and T2.
  • Page 31 R-1750 R-1751 R-1752 R-1754 Pin No. Signal Description Key strobe signal. Signal applied to touch screen section. A pulse signal is input to PB1-PB5 terminal while one of G7 line keys on key matrix is touched. Key strobe signal. Signal applied to touch screen section. A pulse signal is input to PB1-PB5 terminal while one of G8 line keys on key matrix is touched.
  • Page 32 R-1750 R-1751 R-1752 R-1754 Pin No. Signal Description XTAL Internal clock oscillation frequency control input setting. The internal clock frequency is set by inserting the ceramic filter oscillation circuit with respect to XTAL. Power source voltage : +5V. The power source voltage to drive LSI is input to Vcc terminal. Connected to VCC.
  • Page 33 R-1750 R-1751 R-1752 R-1754 ABSOLUTE HUMIDITY SENSOR CIRCUIT resistance balance of the bridge circuit is deviated to (1) Structure of Absolute Humidity Sensor increase the voltage available at AN4 terminal of the LSI. The absolute humidity sensor includes two thermistors Then the LSI observes that voltage at AN4 terminal and as shown in the illustration.
  • Page 34 R-1750 R-1751 R-1752 R-1754 SERVICING 1. Precautions for Handling Electronic Components 4) Re-install the outer case (cabinet). This unit uses CMOS LSI in the integral part of the 5) Re-connect the power supply cord after the outer circuits. When handling these parts, the following case is installed.

  • Page 35: Component Replacement And Adjustment Procedure

    3. The door gasket or seal is damaged. 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 36 R-1750 R-1751 R-1752 R-1754 REMOVAL OF OVEN FROM WALL (It is recommended that two people remove the oven) 1. Disconnect the power supply cord, and uncoil the power 6. While supporting the front of the oven, unfasten the two supply cord.
  • Page 37 R-1750 R-1751 R-1752 R-1754 NOTE: The high voltage wire assembly should be routed inverter unit board. under the bar of thr high voltage transformer. 3. Remove the one (1) screw holding transistor Q1to the heat sink. [HOW TO REMOVE TRANSISTOR Q1] 4.
  • Page 38 R-1750 R-1751 R-1752 R-1754 Top of Oven Cavity 8. Disconnect the wire leads from the thermal cut-out (oven). Thermal 9. Now, the thermal cut-out (oven) is free. Cut-Out Waveguide NOTE: When the tab is broken or turned off, use the another...
  • Page 39 R-1750 R-1751 R-1752 R-1754 7. Re-install the wire leads to the hole of the hood duct. 9. Refer to procedure of "OUTER CASE REMOVAL". And 8. Connect the wire leads to the fan motor and chassis reverse their procedure. And re-install the outer case.
  • Page 40 R-1750 R-1751 R-1752 R-1754 7. Disconnect the wire leads from the relay RY1. 17.Release the nine (9) tabs holding the key fixing plate to 8. Disconnect the connectors CN-A, CN-B, CN-F, CN-E the control panel. and CN-H from the control unit.

  • Page 41: Door Replacement

    R-1750 R-1751 R-1752 R-1754 following adjustment should be made. 2. The contact of primary interlock switch and secondary 5. Loosen the two (2) screws holding latch hook to the oven interlock switch open within 1.2mm gap between right cavity front flange.
  • Page 42 R-1750 R-1751 R-1752 R-1754 latch holes and that latch head goes through center of Note: The door on a microwave oven is designed to latch hole. act as an electronic seal preventing the leakage 2. Deviation of door alignment from horizontal line of cavity of microwave energy from oven cavity during face plate is to be less than 1.0mm.

  • Page 43: Pictorial Diagram

    R-1750 R-1751 R-1752 R-1754...

  • Page 44: Power Unit Circuit

    R-1750 R-1751 R-1752 R-1754 CN-A R2 91 1w R3 91 1w 2SD1859 AC120V 60Hz S1NB10 – BZ/EN MOTOR C100 CAPACITOR 7 /230v INV. COM OVEN LAMP INV. COM FAN MOTOR N.O. OVEN LAMP STIRRER FAN MOTOR MOTOR STIRRER MOTOR TURNTABLE...

  • Page 45: Lsi Unit Circuit

    R-1750 R-1751 R-1752 R-1754 Dots DISPLAY CRYSTAL LIQUID IXA031DR 5G20P40B333J 20kF 43kF 18kF /25v C112 1/2w 4.7k R113 R100 /25v D15/A-1 4.7k R111 R112 BYTE 4.7k R110 1/2w 1SS355 1SS355 WAIT STBY RxD0 TxD0 EXTAL XTAL RES0 /25v TM00 Avcc...

  • Page 46: Printed Wiring Board

    R-1750 R-1751 R-1752 R-1754 H.M H.M H.T H.M CN - B Figure S-4. Printed Wiring Board...

  • Page 47: Parts List

    Outer case cabinet [R-1752] 2- 5 GCABUB084MRP0 Outer case cabinet [R-1754] 2- 6 TMAPCB064MRR0 Schematic diagram 2- 7 FANGKB009MRY0 Hood lamp glass assembly [R-1750] 2- 7 FANGKB010MRY0 Hood lamp glass assembly [R-1751] 2- 7 FANGKB013MRY0 Hood lamp glass assembly [R-1752] 2- 7 FANGKB009MRY0...
  • Page 48 RH-VZA032DRE0 Varistor (10G471K) VHEHZ161///-1 Zener diode (HZ16-1) 3- 2 DUNT-B036MRK0 LSI unit 3- 3 FPNLCB319MRK0 Control panel sub. assembly [R-1750] 3- 3 FPNLCB322MRK0 Control panel sub. assembly [R-1754] 3- 3 FPNLCB326MRK0 Control panel sub, assembly [R-1751] 3- 3 FPNLCB327MRK0 Control panel sub, assembly [R-1752]...
  • Page 49 To have your order filled promptly and correctly, please furnish the following information. 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.
  • Page 50 R-1750 R-1751 R-1752 R-1754 OVEN AND CABINET PARTS 7-10 1-14 1-15 4-13 4-19 4-15 4-10 4-12 4-11 1-12 4-24 4-23 1-13 4-17 6-10    4-15 4-23 4-18 6-12 4-20 4-22 4-20 x2 2-2-1 1-10 1-11 7-11 1-16 4-16...
  • Page 51 R-1750 R-1751 R-1752 R-1754 CONTROL PANEL PARTS 3-3-2 3-3-3 DOOR PARTS 4-21 3-3-1 5-2-3 5-2-1 5-2-5 5-2-2 MISCELLANEOUS 5-2-4 6-1-1 6-1-4 6-1-5 6-16 6-1-2 6-1-6 6-18 6-1-7 6-1-3 6-19 6-15 6-11...

  • Page 52: 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. 2000 SHARP CORP. (8S2.530E) Printed in U.S.A...

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