Sharp R-7H55 Service Manual
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Sharp R-7H55 Service Manual

Sharp R-7H55 Service Manual

Convection microwave oven
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CAUTION, MICROWAVE RADIATION ................................................................................................................. 1
WARNING .............................................................................................................................................................. 1
PRODUCT SPECIFICATIONS ............................................................................................................................. 2
APPEARANCE VIEW ........................................................................................................................................... 3
OPERATION SEQUENCE .................................................................................................................................... 4
FUNCTION OF IMPORTANT COMPONENTS .................................................................................................... 7
SERVICING .......................................................................................................................................................... 9
TEST PROCEDURE ........................................................................................................................................... 12
TOUCH CONTROL PANEL ................................................................................................................................. 20
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ............................................................... 26
MICROWAVE MEASUREMENT ........................................................................................................................ 32
WIRING DIAGRAM ............................................................................................................................................. 33
PICTORIAL DIAGRAM ....................................................................................................................................... 35
CONTROL PANEL CIRCUIT ............................................................................................................................... 36
PRINTED WIRING BOARD ................................................................................................................................. 37
PARTS LIST ....................................................................................................................................................... 38
SERVICE MANUAL
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
S6417R7H55PHR
CONVECTION
MICROWAVE OVEN
R-7H55
R-7H55
Page

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Summary of Contents for Sharp R-7H55

  • Page 1: Table Of Contents

    R-7H55 SERVICE MANUAL S6417R7H55PHR CONVECTION MICROWAVE OVEN R-7H55 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 CAUTION, MICROWAVE RADIATION ......................... 1 WARNING ................................
  • Page 2 R-7H55...

  • Page 3: Caution Microwave Radiation

    MICROWAVE OVEN R-7H55 APPEARANCE VIEW GENERAL IMPORTANT INFORMATION This Manual has been prepared to provide Sharp Corp. Service OPERATING SEQUENCE 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 FUNCTION OF IMPORTANT satisfactory customer service.

  • Page 4: Product Specifications

    R-7H55 PRODUCT SPECIFICATIONS ITEM DESCRIPTION Power Requirements 220 Volts 50 Hertz Single phase Power Consumption Microwave 1.4 kW Convection: 1.57 kW Power Output 850 W nominal of RF microwave energy (IEC 705) Operating frequency 2450 MHz Convection heating element 1500 W...

  • Page 5: Appearance View

    R-7H55 APPEARANCE VIEW 1. Ventilation opening 10.Digital read-out 2. Oven lamp 11.Wave guide cover 3. Door hinges 12.Convection air opening 4. Door safety latches 13.Power supply cord 5. See through door 14.Rating label 6. Door seals and sealing surfaces 15.Low lack 7.

  • Page 6: Operation Sequence

    R-7H55 OPERATING SEQUENCE OFF CONDITION The circuits to the power transformer and turntable motor are cut off when the 1st latch switch and 2nd latch Closing the door activates all door interlock switches switch are made open. The fan motor is cut off when the (1st latch switch, 2nd latch switch and stop switch).
  • Page 7 R-7H55 2. The coil of relay (RY6) is energized by the CPU unit. The on the oven lamp, turntable motor, cooling fan motor and damper is moved to the closed position, opening the convection motor. damper switch contacts. The opening of the damper 3.
  • Page 8 R-7H55 SENSOR COOKING CONDITION The shut-off relays and cook relay are de-energized and the power transformer, oven lamp, etc. are turned off. Using the SENSOR REHEAT, SENSOR RICE COOK or 6. Opening the door or touching the STOP/CLEAR pad, the...

  • Page 9: Function Of Important Components

    R-7H55 FUNCTION OF IMPORTANT COMPONENTS The rated peak reverse voltage of D1 of the asymmetric DOOR OPEN MECHANISM rectifier is 6 KV The rated peak reverse voltage of D2 of the The door is opened by asymmetric rectifier is 1.7 KV. D1 and D2 of the asymmetric...
  • Page 10 R-7H55 THERMISTOR DAMPER OPEN-CLOSE MECHANISM The thermistor is a negative temperature coefficient type. Usually, the damper is in the open position except during The temperature in the oven cavity is detected through the convection cooking. resistance of the thermistor, and then the control unit cause...

  • Page 11: Servicing

    3D checks and re-examine the connections to the 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...
  • Page 12 R-7H55 CK = Check / RE = Replace A B C D E E E E G G G H H H TEST PROCEDURE POSSIBLE CAUSE DEFECTIVE PARTS PROBLEM CONDITION Home fuse blows when power supply cord is plugged into wall outlet.
  • Page 13 R-7H55 H E RE L M N N N N N N CK RE RE CK K P CK O Q...

  • Page 14: Test Procedure

    R-7H55 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 CHECK Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
  • Page 15 R-7H55 TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 6. Measure the final water temperature. (Example: The final temperature T2 = 21°C) 7. Calculate the microwave power output P in watts from above formula. Initial temperature ....................T1 = 11°C Temperature after (49 + 2) = 51 sec..............T2 = 21°C Temperature difference Cold-Warm..............
  • Page 16 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE LETTER COMPONENT TEST CARRY OUT 4R CHECKS ASYMMETRIC ASYMMETRIC RECTIFIER TEST RECTIFIER CARRY OUT 3D CHECKS. HIGH VOLTAGE RECTIFIER Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric can be tested using an ohmmeter set to its highest range across the terminals A+B of the asymmetric rectifier and note the reading obtained.
  • Page 17 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER 3. If the fuse M8A is blown, there could be a short in the asymmetric rectifier or there could be a ground in wire harness. A short in the asymmetric rectifier may have occured due to sh ort or ground in H.V.
  • Page 18 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER 2. Insulation resistance Disconnect the wire leads to the heater to be tested. Check the insulation resistance between the element and cavity using a 500V - 100Mohms insulation tester. The insulation resistance should be more than 10Mohms in the cold start.
  • Page 19 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER 2-3 Other possible problems 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. KEY UNIT TEST If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon is marking good contact, verify that the door sensing switch(stop switch) operates properly;...
  • Page 20 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER 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 primary on the PWB, this foil pattern acts as a fuse.
  • Page 21 R-7H55 TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER (5) After approximately 16 seconds, microwave energy is produced, oven should turn off when water is boiling (bubling). If the oven does not turn off, replace the AH sensor or check the control unit, refer to explanation below.

  • Page 22: Touch Control Panel

    R-7H55 TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOIUCH CONTROL PANEL The touch control section consists of the following units as 4) ACL Circuit shown in the touch control panel circuit. A circuit to generate a signals which resets the LSI to the initial state when power is supplied.
  • Page 23 R-7H55 DESCRIPTION OF LSI LSI(IZA573DR) The I/O signal of the LSI(IZA573DR) is detailed in the following table. Pin No. Signal Description Damper motor relay driving signal. To turn on and off shut-off relay (RY6). Convection motor driving signal. During To turn on and off shut-off relay (RY5). "L" level...
  • Page 24 R-7H55 Pin No. Signal Description AVSS Reference voltage input terminal. A reference voltage apllied to the A/D converter in the LSI. T he reference voltage is generally maintaned at -5V. Temperature measurement input: OVEN THERMISTOR. By inputting DC voltage corresponding to the temperature detected by the themistor, this input is converted into temperature by the A/D converter built into the LSI.
  • Page 25 R-7H55 Pin No. Signal Description Key strobe signal. Signal applied to touch-key section. A pulse signal is input to R20-R23 terminal while one of G-1 line keys on key matrix is touched. Terminal not used. Key strobe signal. Signal applied to touch-key section. A pulse signal is input to R20-R23 terminal while one of G-3 line keys on key matrix is touched.
  • Page 26 R-7H55 ABSOLUTE HUMIDITY SENSOR CIRCUIT (1) Structure of Absolute Humidity Sensor With this voltage given, the switches SW1 to SW5 in the LSI are turned on in such a way as to change the The absolute humidity sensor includes two thermistors resistance values in parallel with R1.
  • Page 27 R-7H55 SERVICING 1. Precautions for Handling Electronic Components B. On some models, the power supply cord between the touch control panel and the oven proper is long enough This unit uses CMOS LSI in the integral part of the that they may be separated from each other. For those circuits.

  • Page 28: Component Replacement And Adjustment Procedure

    R-7H55 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING: AVOID POSSIBLE EXPOSURE TO MICROWAVE ENERGY. PLEASE FOLLOW THE INSTRUCTIONS BELOW BEFORE OPERATING THE OVEN. 1. CARRY OUT 3D CHECKS. 1. Door does not close firmly. 2. Make sure that a definite” click” can be heard when the 2.
  • Page 29 R-7H55 HIGH VOLTAGE RECTIFIER ASSEMBLY REMOVAL 1. CARRY OUT 3D CHECKS. from the power transformer. 2. Remove one (1) screw holding the rectifier assembly to CAUTION: WHEN REPLACING THE HIGH VOLTAGE the capacitor holder. RECTIFIER ASSEMBLY, THE GROUND SIDE 3. Disconnect the rectifier assembly from the capacitor.
  • Page 30 R-7H55 * Make sure that the fan blade rotates smooth after installation. * Make sure that the axis of the shaft is not slanted. 4. Reset the fan duct assembly to its place. 5. Install the fan duct to the waveguide with the two (2) screws.
  • Page 31 R-7H55 plates to the convection duct. fan to convection motor shaft. 13.Remove two (2) screws holding the convection heater to 18.Remove two (2) screws holding the convection motor the convection duct. mounting plate to convection duct. 14.Now, convection heater is free.
  • Page 32 R-7H55 1ST. LATCH SWITCH, 2ND. LATCH SWITCH,STOP SWITCH AND MONITOR SWITCH ADJUSTMENT If the 1st. latch switch, 2nd. latch switch and monitor switch should be less than 0.5mm. do not operate properly due to a misadjustment, the follow- 2. The 2nd. latch switch and stop switch interrupt the circuit ing adjustment should be made.
  • Page 33 R-7H55 2. Deviation of door alignment from horizontal line of cavity face plate is to be less than 1.0mm. SCREWS 3. Door is positioned with its face pressed toward cavity UPPER DOOR HINGE PIN face plate. 4. Re-install outer case and check for microwave leakage...

  • Page 34: Microwave Measurement

    R-7H55 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 35: Wiring Diagram

    R-7H55 SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED 2. CLOCK OR APPEARS ON DISPLAY THERMAL THERMAL CUT-OUT CUT-OUT NOISE FILTER 2ND LATCH 145˚C(MG) 150˚C(CONV.) SWITCH AH. SENSOR N.O. N.O. N.O. POWER CONTROL UNIT TRANSFORMER 220 V ~50Hz COM. COM.
  • Page 36 R-7H55 SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME PROGRAMMED. 3. "CONVEC" PAD TOUCHED. 4. DESIRED TEMPERATURE ENTERED. 5. START PAD TOUCHED. THERMAL THERMAL CUT-OUT CUT-OUT NOISE FILTER 2ND LATCH 145˚C(MG) 150˚C(CONV.) SWITCH AH. SENSOR N.O. N.O.

  • Page 37: Pictorial Diagram

    R-7H55...

  • Page 38: Control Panel Circuit

    R-7H55...

  • Page 39: Printed Wiring Board

    R-7H55 Figure S-3. Printed Wiring Board...

  • Page 40: Parts List

    R-7H55 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 FH-HZA007WRE0 Thermistor 1- 2...
  • Page 41 R-7H55 ∆ 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 VRD-B12EF473J Resistor 47k ohm 1/4W VRD-B12EF563J Resistor 56k ohm 1/4W...
  • Page 42 R-7H55 ∆ 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 4-43 LSTPPA070WRF0 Cord anchorage (Lower) 4-44 LANG-A047WRP0 Magnetron duct DOOR PARTS ∆...
  • Page 43 R-7H55 OVEN AND CABINET PARTS 7-17 7-17 7-25 6-12 4-24 6-15 7-22 7-18 6-13 7-15 1-12 7-25 4-43 7-18 4-42 1-13 7-19 7-18 7-18 4-40 1-20 1-19 7-22 1-17 1-21 1-18 4-28 4-37 7-25 4-33 7-25 4-16 4-18 7-14 7-24...
  • Page 44 R-7H55 CONTROL PANEL PARTS DOOR PARTS 3-2-1 MISCELLANEOUS 6-14 Actual wire harness may be different from illustrations. 6-10 6-13 6-11 80±5 PACKING AND ACCESSORIES PAD ASSEMBLY CPADBA176WRK0 DOOR PROTECTOR SPADPA204WRE0 TRAY HOLDER WRAP COVER SPADFA340WRE0 SSAKHA034WRE0 TURNTABLE TRAY HIGH RACK...

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