Sharp R-7N76(B)M Service Manual
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Sharp R-7N76(B)M Service Manual

Sharp R-7N76(B)M Service Manual

Grill and convection microwave oven
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LogiCook
R-7N76M
CAUTION, MICROWAVE RADIATION ........................................................................................................ 1
WARNING ................................................................................................................................................... 1
PRODUCT SPECIFICATIONS ................................................................................................................... 2
APPEARANCE VIEW ................................................................................................................................. 3
OPERATION SEQUENCE .......................................................................................................................... 4
FUNCTION OF IMPORTANT COMPONENTS .......................................................................................... 6
SERVICING ................................................................................................................................................ 9
TEST PROCEDURE ................................................................................................................................. 12
TOUCH CONTROL PANEL ...................................................................................................................... 21
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................... 29
MICROWAVE MEASUREMENT .............................................................................................................. 34
WIRING DIAGRAM ................................................................................................................................... 35
PICTORIAL DIAGRAM ............................................................................................................................. 38
CONTROL PANEL CIRCUIT .................................................................................................................... 39
PRINTED WIRING DIAGRAM .................................................................................................................. 40
PARTS LIST ............................................................................................................................................. 41
SERVICE MANUAL
®
TEMP
CONV
GRILL
MED
LOW
HIGH
AUTO
DEFROST
COOK
Lbs
Pcs
Kg
Oz
1O
1
1O
MIN.
MIN.
SEC.
LOGICOO K
FOOD
DRINK
Kg•Lb g • oz
LESS
MORE
DUAL
MICROWAVE
CONVECTION
CONVECTION
POWER LEVEL
TEMP
/GRILL
STOP/
GRILL
AUTO MINUTE
CLEAR
/ START
TIMER
AUTO
Kg / Lb
/
/ HOLD
START
R-7N76
850W
E
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
GRILL AND CONVECTION
MICROWAVE OVEN
MODELS
R-7N76(W)M
R-7N76(B)M
R-7N76(W)M
R-7N76(B)M
S6538R7N76M//
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  • Page 1: Table Of Contents

    R-7N76(W)M R-7N76(B)M SERVICE MANUAL ® S6538R7N76M// TEMP CONV GRILL HIGH GRILL AND CONVECTION AUTO LogiCook DEFROST COOK MIN. MIN. SEC. MICROWAVE OVEN LOGICOO K FOOD DRINK Kg•Lb g • oz MODELS LESS MORE DUAL MICROWAVE CONVECTION CONVECTION POWER LEVEL TEMP...

  • Page 2: Caution Microwave Radiation

    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 3: Product Specifications

    R-7N76(W)M R-7N76(B)M PRODUCT DESCRIPTION SPECIFICATION ITEM DESCRIPTION Power Requirements 240 Volts / 50 Hertz / Single phase, 3 wire earthed Power Consumption Microwave cooking 1.45 kW Approx. 7.1A Dual cooking (Roast/Bake) 2.75 kW Approx. 12.3A Dual cooking (Grill) 2.65 kW Approx. 11.4A Convection cooking 1.4 kW Approx.

  • Page 4: Appearance View

    R-7N76(W)M R-7N76(B)M APPEARANCE VIEW OVEN Door Door hinges Grill heating elements Oven lamp Ventilation openings Wave guide cover Outer cabinet Control panel Rear cabinets Coupling Door lock openings Oven cavity Power supply cord Door seals and sealing surfaces Safety door latches...

  • Page 5: Operation Sequence

    R-7N76(W)M R-7N76(B)M OPERATION SEQUENCE cycle has been interrupted, because the relay RY1 stay OFF CONDITION closed. Shown in the display is remaining time. Closing the oven door activates all door interlock switches 6. MONITOR SWITCH CIRCUIT (1st. latch switch, 2nd. latch switch and stop switch.)
  • Page 6 R-7N76(W)M R-7N76(B)M heat temperature, the following operations occur; 3. Relay RY3 is energized (If the cavity temperature is lower than the selected temperature) and the main 3-1. The shut-off relay RY3 is de-energized by the control supply voltage is applied to the convection heating unit temperature circuit and thermistor, opening the element.

  • Page 7: Function Of Important Components

    R-7N76(W)M R-7N76(B)M FUNCTION OF IMPORTANT COMPONENTS DOOR OPEN MECHANISM FUSE 13A 250V The door can be opened by pushing the open button on the If the wire harness or electrical components are short- control panel. When the open button is pushed, the open circuited, this fuse 13A 250V blows to prevent an electric lever pushes lower latch head on the door upward.
  • Page 8 R-7N76(W)M R-7N76(B)M The rated peak reverse voltage of D1 of the asymmetric convection heating element, passes through the convection rectifier is 6 KV. The rated peak reverse voltage of D2 of the passage and enters the inside of the oven cavity again, in a asymmetric rectifier is 1.7 KV.
  • Page 9 R-7N76(W)M R-7N76(B)M motor is energized, opening the damper door. The oven will stop its operation when the difference of the voltages is more than 0.3 volts in microwave cooking 1-3. When the damper is moved to the open position by the condition.

  • Page 10: 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 the outer...
  • Page 11 R-7N76(W)M R-7N76(B)M A B C D E E E E F E G G G H TEST PROCEDURE POSSIBLE CAUSE DEFECTIVE PARTS PROBLEM CONDITION Fuse M8A browns when the door is opened. Home fuse blows when power cord is plugged into wall outlet.
  • Page 12 R-7N76(W)M R-7N76(B)M H H H I J K L L M...

  • Page 13: Test Procedure

    R-7N76(W)M R-7N76(B)M 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 CHECK Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
  • Page 14 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER Initial temperature ....................T1 = 11°C Temperature after (49 + 3) = 52 sec..............T2 = 21°C Temperature difference Cold-Warm ..............∆T1 = 10°C Measured output power The equation is “P = 85 x ∆T” ............P = 85 x 10°C = 850 Watts ±...
  • Page 15 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER 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 16 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER THERMAL CUT-OUT TEST CARRY OUT 3D CHECKS Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a continuity test across the two terminals as described in the below.
  • Page 17 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER FUSE 13A CARRY OUT 3D CHECKS If the fuse 13A is blown, there is a shorts or grounds in electrical parts or wire harness. Check them and replace the defective parts or repair the wire harness.

  • Page 18: Key Unit

    R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) 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 19 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE COMPONENT TEST LETTER RELAY TEST 1. CARRY OUT 3D CHECKS. 2. Disconnect the leads from the primary of the high voltage transformer. Make sure that the leads remain isolated from other oven components and chassis. (Use insulation tape if necessary.) 3.
  • Page 20 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE LETTER COMPONENT TEST AH SENSOR TEST Checking the initial sensor cooking condition (1) The oven should be plugged in at least five minutes before sensor cooking. (2) Room temperature should not exceed 35˚C. (3) The unit should not be installed in any area where heat and steam are generated. The unit should not be installed, for example, next to a conventional surface unit.
  • Page 21 R-7N76(W)M R-7N76(B)M TEST PROCEDURES (CONT'D) PROCEDURE LETTER COMPONENT TEST If the above is not the case, the control unit is probably defective. If the above is proper, the AH sensor is probably defective Plunger To connector (F) on Control Unit.

  • Page 22: Touch Control Panel

    R-7N76(W)M R-7N76(B)M TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units as 3) Synchronizing Signal Circuit shown in the touch control panel circuit. The power source synchronizing signal is available in...
  • Page 23 R-7N76(W)M R-7N76(B)M DESCRIPTION OF LSI LSI(IZA627DR) The I/O signal of the LSI(IZA627DR) are detailed in the following table. Pin No. Signal Description Connected to GND. Anode (segment) of Fluorescent Display illumination voltage: -26V. Vp voltage of power source circuit input.
  • Page 24 R-7N76(W)M R-7N76(B)M Pin No. Signal Description Grill heater driving signal. During To turn on and off the grill heater relay cooking (RY4). "L" level during grill or dual cooking; (Grill or dual) "H" level otherwise. 0.12 sec. Signal to sound buzzer.
  • Page 25 R-7N76(W)M R-7N76(B)M Pin No. Signal Description 37-42 P23-P16 Digit selection signal. ß(50Hz) The relation between digit signal and digit are as follows: Digit signal digit P23 ........... 1st. P22 .......... 2nd. P21 ........... 3rd. P20 ........... 4th. P17 ........... 5th.
  • Page 26 R-7N76(W)M R-7N76(B)M Pin No. Signal Description 52-56 P04-P00 Segment data signal. Signal similar to P15. 57-59 P37-P35 Terminal not used. 60-64 P34-P30 Used for initial balancing of the bridge circuit (absolute humidity sensor). 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 8 bits, enabling individual access, read and write operations to be performed.
  • Page 27 R-7N76(W)M R-7N76(B)M ABSOLUTE HUMIDITY SENSOR CIRCUIT unit is put in the Sensor Cooking mode. (1) Structure of Absolute Humidity Sensor As the sensor cooking proceeds, the food is heated to The absolute humidity sensor includes two thermistors generate moisture by which the resistance balance of as shown in the illustration.
  • Page 28 R-7N76(W)M R-7N76(B)M SERVICING be separated from each other. For those models, 1. Precautions for Handling Electronic Components therefore, check and repair all the controls (with the This unit uses CMOS LSI in the integral part of the sensor-related ones included) of the touch control panel circuits.
  • Page 29 R-7N76(W)M R-7N76(B)M SERVICE INFORMATION AUTOMATIC GAIN SETTING FOR LOGICOOK MANUAL GAIN SETTING FOR DRINK OF LOGICOOK 1. Set the gain of IC2 in no load condition each time after 1. When, though the microwave oven or all parts are the following service action, referring to the Table 1 normal, food is undercooked or overcooked in DRINK of "How to set the gain".

  • Page 30: Component Replacement And Adjustment Procedure

    R-7N76(W)M R-7N76(B)M COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven. 1. Door does not close firmly. 1. CARRY OUT 3D CHECKS. 2. Door hinge, support or latch hook is damaged.

  • Page 31: Magnetron Removal

    R-7N76(W)M R-7N76(B)M MAGNETRON REMOVAL 1. CARRY OUT 3D CHECKS. to prevent it from falling. 2. Remove the air separate duct B from the chassis support 8. Remove the magnetron from the waveguide with care so and the air intake duct.

  • Page 32: Oven Lamp Socket Removal

    R-7N76(W)M R-7N76(B)M OVEN LAMP SOCKET REMOVAL OVEN LAMP SOCKET TERMINAL 1. CARRY OUT 3D CHECKS 2. Pull the wire leads from the oven lamp socket by WIRE LEAD FLAT TYPE SMALL SCREW pushing the terminal hole of the oven lamp socket DRIVER with the flat type small screw driver.
  • Page 33 R-7N76(W)M R-7N76(B)M mounting plate to the convection fan duct. CONVECTION FAN MOTOR 9. Remove the pin on the convection fan motor shaft. 7. Remove the one (1) nut holding the convection fan, washers, pipe and auxiliary fan to the convection fan 10.Remove the two (2) screws holding the convection motor...
  • Page 34 R-7N76(W)M R-7N76(B)M DOOR REPLACEMENT AND ADJUSTMENT REPLACEMENT 1. Adjust door latch heads at a position where they smoothly catch the latch hook through the latch holes. Refer to 1. CARRY OUT 3D CHECKS latch switch adjustments. 2. Remove three (3) screws holding the lower oven hinge to 2.

  • Page 35: Microwave Measurement

    R-7N76(W)M R-7N76(B)M MICROWAVE MEASUREMENT After adjustment of door latch switches, monitor switch Recommended instruments are: and door are completed individually or collectively, the NARDA 8100 following leakage test must be performed with a survey NARDA 8200 instrument and it must be confirmed that the result meets...

  • Page 36: Wiring Diagram

    R-7N76(W)M R-7N76(B)M SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. CLOCK APPEARS ON DISPLAY. 1ST LATCH SWITCH Figure O-1 Oven Schematic-OFF Condition SCHEMATIC NOTE: CONDITION OF OVEN NOTE: * Indicates components with potentials above 250V. 1. DOOR CLOSED. 2. COOKING TIME PROGRAMMED.
  • Page 37 R-7N76(W)M R-7N76(B)M SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME PROGRAMMED. 3. CONVECTION PAD TOUCHED UNTIL THE DESIRED TEMPERATURE APPEAR ON DISPLAY 4. START PAD TOUCHED. 1ST LATCH SWITCH Figure O-3 Oven Schematic-Convection Cooking Condition SCHEMATIC NOTE: CONDITION OF OVEN 1.
  • Page 38 R-7N76(W)M R-7N76(B)M SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME PROGRAMMED. 3. DUAL COOK PAD TOUCHED ONCE OR TWICE. 4. START PAD TOUCHED. 1ST LATCH SWITCH Figure O-5. Oven Schematic-Dual Cooking (Roast / Bake) Condition SCHEMATIC NOTE: CONDITION OF OVEN 1.

  • Page 39: Pictorial Diagram

    FUSE M8A...

  • Page 40: Control Panel Circuit

    (J1) C1 0.1µ/50V 0.1µ /50V C2 1000µ/50V 10µ 4.3K 1/2W HZ6A3 /35V 0.1µ/50V R2 2.4K R40 3.3K ZD2 HZ16-1 C50 47µ/25V C3 47µ/25V 1.5K SP40 C4 0.1µ/50V (J8) TEST ZD3 HZ5C2 (J6) C5 47µ/25V 1.5K (J4) (J7) (J5) HZ4A2 (J3) R62 2.7KF 100F R5 15K...

  • Page 41: Printed Wiring Diagram

    R-7N76(W)M R-7N76(B)M Figure S-3. Printed Wiring Board...

  • Page 42: Parts List

    R-7N76(W)M R-7N76(B)M PARTS LIST Note: The parts marked " ∆ " may cause undue microwave exposure. / The parts marked "*" are used in voltage more than 250V. / "§" Mark: Spare parts delivery section REF. NO. PART NO. §...

  • Page 43: Oven Parts

    Zener diode (HZ6A3) VHEHZ161///-1 Zener diode (HZ16-1) VHEHZ5C2///-1 Zener diode (HZ5C2) VHEHZ4A2///-1 Zener diode (HZ4A2) 3- 2 DUNTKA654WRK0 Key unit assembly [R-7N76(B)M] 3- 2 DUNTKA655WRK0 Key unit assembly [R-7N76(W)M] 3- 2-1 FUNTKA666WRE0 Key unit [R-7N76(B)M] 3- 2-1 FUNTKA667WRE0 Key unit [R-7N76(W)M]...

  • Page 44: Door Parts

    R-7N76(W)M R-7N76(B)M ∆ Note: The parts marked " " may cause undue microwave exposure. / The parts marked "*" are used in voltage more than 250V. / "§" Mark: Spare parts delivery section REF. NO. PART NO. § DESCRIPTION Q'TY CODE...
  • Page 45 R-7N76(W)M R-7N76(B)M ∆ Note: The parts marked " " may cause undue microwave exposure. / The parts marked "*" are used in voltage more than 250V. / "§" Mark: Spare parts delivery section REF. NO. PART NO. § DESCRIPTION Q'TY CODE...
  • Page 46 R-7N76(W)M R-7N76(B)M OVEN PARTS 6-12 7-20 6-11 4-43 4-41 4-44 4-42 4-38 7-20 4-33 7-16 1-28 7-20 7-22 4-30 1-13 4-40 4-13 4-11 7-20 4-36 7-20 7-11 7-20 7-10 1-15 7-13 7-12 7-18 7-22 7-24 1-26 7-16 4-10 1-11 7-23...
  • Page 47 R-7N76(W)M R-7N76(B)M CONTROL PANEL PARTS 3-2-1 DOOR PARTS 5-10 5-10...

  • Page 48: Packing And Accessories

    COOK BOOK & INSTRUCTION BOOK (SSAKHA045WRE0) ROLLER STAY BOTTOM PAD ASSEMBLY TRAY PAD *(FPADBA273WRK1) *(SPADPA474WRE1) PACKING CASE *Not Replaceable Items *(SPAKCC537WRR0); R-7N76(B)M *(SPAKCC538WRR0); R-7N76(W)M N.B: ALL BROWN MICROWAVE OVENS MUST BE PACKED WITH A PAPER SHEET ON TOP OF THE OUTER WRAP...
  • Page 49 R-7N76(W)M R-7N76(B)M ® SHARP CORP 95 Printed in UK...

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