Sharp R-240B Service Manual
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Sharp R-240B Service Manual

Sharp R-240B Service Manual

Microwave oven
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CAUTION, MICROWAVE RADIATION ................................................................................................................. 1
WARNING .............................................................................................................................................................. 1
PRODUCT SPECIFICATIONS ............................................................................................................................. 2
GENERAL INFORMATION .................................................................................................................................... 2
APPEARANCE VIEW ........................................................................................................................................... 3
OPERATION SEQUENCE .................................................................................................................................... 4
FUNCTION OF IMPORTANT COMPONENTS .................................................................................................... 5
SERVICING ........................................................................................................................................................... 6
TEST PROCEDURE ............................................................................................................................................. 8
TOUCH CONTROL PANEL ................................................................................................................................. 14
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ............................................................... 18
MICROWAVE MEASUREMENT ........................................................................................................................ 24
WIRING DIAGRAM ............................................................................................................................................. 25
PICTORIAL DIAGRAM ....................................................................................................................................... 26
CONTROL PANEL CIRCUIT ............................................................................................................................... 27
PRINTED WIRING BOARD ................................................................................................................................. 28
PARTS LIST ....................................................................................................................................................... 29
MODEL
COOK
DEF
KG
QTY
CHEC K
1. Stea k /
Cho ps
2. Roa st
Mea t
3. Pou ltry
EA SY
4. Chi cke
n Piec es
DEF RO ST
RE HE AT
DIN NE R
PLA TE
BE VE RA
GE
CO OK ING
FR ES H
VEG ETA BLE
FR OZ EN
S
VEG ETA BLE
S
JAC KE T
PO TA TO
RIC E
PA ST A
PO WE R
LEV EL
TIM ER
CLO CK
STO P
INS TAN T
CLE AR
COO K
STA RT
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
MICROWAVE OVEN
R-240B
R-240B
S6805R240BPJ/

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  • Page 1: Table Of Contents

    R-240B SERVICE MANUAL S6805R240BPJ/ MICROWAVE OVEN R-240B MODEL COOK CHEC K 1. Stea k / Cho ps 2. Roa st Mea t 3. Pou ltry EA SY 4. Chi cke n Piec es DEF RO ST RE HE AT DIN NE R...
  • Page 2 R-240B...

  • Page 3: Caution Microwave Radiation

    PRODUCT SPECIFICATIONS R-240B GENERAL IMPORTANT INFORMATION APPEARANCE VIEW 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 OPERATING SEQUENCE entire text of this manual, so they will be qualified to render satisfactory customer service.

  • Page 4: Product Specifications

    R-240B PRODUCT SPECIFICATIONS ITEM DESCRIPTION Power Requirements 230 - 240 Volts 50 Hertz Single phase, 3 wire earthed Power Consumption 1.2 kW Power Output 800 watts nominal of RF microwave energy (IEC 705) Operating frequency 2450 MHz Case Dimensions Width 460 mm...

  • Page 5: Appearance View

    R-240B APPEARANCE VIEW OVEN 1. Ventilation openings 7. Coupling 2. Oven lamp 8. Control panel 3. Door hinges 9. Waveguide cover 4. Door safety latches 10. Power supply cord 5. See through door 11. Turntable 6. Door seals sealing surfaces 12.

  • Page 6: Operation Sequence

    R-240B OPERATION SEQUENCE OFF CONDITION The oven lamp remains on even if the oven door is Closing the door activates all door interlock switches opened after the cooking cycle has been interrupted, (1st. latch switch, 2nd. latch switch and stop switch).

  • Page 7: Function Of Important Components

    R-240B FUNCTION OF IMPORTANT COMPONENTS THERMAL CUT-OUT 125˚C (OVEN) DOOR OPEN MECHANISM The thermal cut-out located on the top of the oven cavity The door is opened by pulling the door, refer to the Figure is designed to prevent damage to the oven if the foods in D-1.

  • Page 8: Servicing

    3D checks and re-examine the connections to the screwdriver. component being tested. Sharp recommend that wherever possible fault-finding is carried out with the supply disconnected. It may in, some cases, be necessary to connect the supply after the outer case has been removed, in this event carry out 3D checks and then disconnect the leads to the primary of the power transformer.
  • Page 9 R-240B CK = Check / RE = Replace TEST PROCEDURE A B C D E E E E F G G H H I L N O J M K RECK CKRECKCKCKCKCK POSSIBLE CAUSE DEFECTIVE PARTS PROBLEM CONDITION Home fuse blows when power supply cord is plugged into wall outlet.

  • Page 10: Test Procedure

    R-240B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 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 the high voltage circuit by removing all leads connected to the filament terminal.
  • Page 11 R-240B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER Initial temperature ....................T1 = 11 C Temperature after (52 + 2) = 54 sec..............T2 = 21 C Temperature difference Cold-Warm..............T1 = 10 C Measured output power The equation is “P = 80 x T” ............P = 80 x 10 C = 800 Watts JUDGMENT: The measured output power should be at least 15 % of the rated output power.
  • Page 12 R-240B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER HIGH VOLTAGE CAPACITOR TEST CARRY OUT 3D CHECKS. A. Isolate the high voltage capacitor from the circuit. B. Continuity check must be carried out with measuring instrument which is set to the highest resistance range.
  • Page 13 R-240B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER to resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV circuit. An open circuit temperature fuse (OVEN) indicates that the food in the oven cavity may catch fire, this may be due to overheating produced by improper setting of the cooking time or failure of the control panel.
  • Page 14 R-240B 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 15 R-240B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 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.

  • Page 16: Touch Control Panel

    R-240B TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units as 3) Power Source Circuit shown in the touch control panel circuit. This circuit generates voltage necessary in the control unit from the AC line voltage. In addition, the synchro-...
  • Page 17 R-240B DESCRIPTION OF LSI LSI(IZA906DR) The I/O signal of the LSI(IZA906DR) are detailed in the following table. Pin No. Signal Description 1-12 Segment data signal. SEG0-SEG11 Connected to LCD. The relation between signals are as follows: LSI signal (Pin No.) LCD (Pin No.)
  • Page 18 R-240B Pin No. Signal Description INT2 Signal synchronized with commercial power source frequency. This is the basic timing for time processing of LSI. H : GND L : -5V 20.0 msec Key strobe signal. Signal applied to touch-key section. A pulse signal is input to R60 - R63 terminal while one of G6 line keys on key matrix is touched.
  • Page 19 R-240B SERVICING 1. Precautions for Handling Electronic Components proper is so long enough that they may be This unit uses CMOS LSI in the integral part of the separated from each other. For those models, circuits. When handling these parts, the following pre- therefore, it is possible to check and repair the cautions should be strictly followed.

  • Page 20: Component Replacement And Adjustment Procedure

    Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any of the following removal procedures: WARNING FOR WIRING and Oven cavity. To prevent an electric shock, take the following 3) Sharp edge: manners. Bottom plate, Oven cavity, Weveguide flange, 1. Before wiring, Chassis support and other metallic plate.
  • Page 21 R-240B HIGH VOLTAGE COMPONENTS REMOVAL (HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE RECTIFIER ASSEMBLY AND H.V. FUSE) 8. Disconnect the H.V. fuse from the high voltage capacitor. To remove the components, proceed as follows. 9. Now H.V. rectifier assembly, H.V. fuse and H.V. ca- 1.
  • Page 22 Re-install oven cavity. 3. Turn the oven over. 1. Remove the any sharp edges on the turntable motor 4. Cut the four (4) bridges holding the turntable motor cover and the bottom plate with the cutting pliers. cover to the bottom plate with the cutting pliers as 2.
  • Page 23 R-240B FAN MOTOR REPLACEMENT REMOVAL 1. CARRY OUT 3D CHECKS. 14. Remove the two (2) screws holding the fan motor to 2. Disconnect the wire leads from the fan motor. the fan duct. 3. Remove the one (1) screw holding the chassis support 15.
  • Page 24 R-240B 1ST. LATCH SWITCH, 2ND. LATCH SWITCH, STOP SWITCH AND MONITOR SWITCH REMOVAL 1. CARRY OUT 3D CHECKS. middle position. The stop switch and 2nd. latch switch 2. Disconnect wire leads from the switches and control are in the upper position.
  • Page 25 R-240B DOOR REPLACEMENT 2. Deviation of door alignment from horizontal line of REMOVAL cavity face plate is to be less than 1.0mm. 1. Disconnect the power supply cord. 3. Door is positioned with its face pressed toward cavity 2. Open the door slightly.

  • Page 26: Microwave Measurement

    R-240B MICROWAVE MEASUREMENT Recommended instruments are: After adjustment of door latch switches, monitor switch NARDA 8100 and door are completed individually or collectively, the NARDA 8200 following leakage test must be performed with a survey instrument and it must be confirmed that the result meets...

  • Page 27: Wiring Diagram

    R-240B SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. CLOCK APPEARS ON DISPLAY. NOTE: " " indicates components with potential above 250V. THERMAL CUT-OUT 95˚C (MG) 2ND. LATCH SWITCH NOISE FILTER COM. N.O. THERMAL CUT-OUT 125˚C (OVEN) 1ST. LATCH...

  • Page 28: Pictorial Diagram

    R-240B...

  • Page 29: Control Panel Circuit

    R-240B 10kF /16v 0.01 IZA906DR 220k 220k 220k (J6) (J7) 220k /50v (J4) (J5) (J2) (J3) 2SA933 HZ4C3 /16v 0.01 /16v /16v 0.01 4.7k /16v 0.01 – 3.3k /25v /50v SP30 (J1) VRS1...

  • Page 30: Printed Wiring Board

    R-240B (J7) (J5) (J3) (J6) (J4) (J2) (J1) CN - B DOOR SW AC (N) FM TTM Figure S-3. Printed Wiring Board...

  • Page 31: Parts List

    R-240B 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-MA131WRE0 1st. latch switch & 2nd. latch switch & stop switch...
  • Page 32 R-240B 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 RRLY-A094DRE0 Relay (OMIF-S-112LM) SP30 RALM-A014DRE0 Buzzer (PKM22EPT-CA) RTRNPA114DRE0 Transformer VRS1...
  • Page 33 R-240B INFORMATION FOR PARTS CHANGE The door screen will be changed as follows, and new part will be used from Sep. 1998 production (Serial No. from 9809xxxxx). Interchangeability A. OLD B. OLD C. OLD D. OLD REPLACEMENT PART NO. Interchange- REF.NO.
  • Page 34 R-240B OVEN AND CABINET PARTS 1-13 1-16 1-15 4-14 1-17 1-11 4-11 1-14 4-13 7-11 4-10 1-10 4-12 1-12 7-10 7-10...
  • Page 35 R-240B Before attaching Control unit to Control panel. Foil side of Control CONTROL PANEL PARTS unit must be cleaned by ethyl- alcohol. 3-2-2 DOOR PARTS 3-2-1 MISCELLANEOUS Actual wire harness may be different than illustration.
  • Page 36 R-240B '98SHARP CORP. (6S0.730E) Printed in Australia...

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