Sharp R-772WM Service Manual
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Sharp R-772WM Service Manual

Sharp R-772WM Service Manual

Microwave oven with top and bottom grills
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SERVICE MANUAL
MICROWAVE OVEN WITH TOP
AND BOTTOM GRILLS
R-772(W)M/ R-772(G)M
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.
MICROWAVE RADIATION
Personnel should not be exposed to the microwave energy
which may radiate from the magnetron or other microwave
generating devices if it is improperly used or connected. All input
and output microwave connections, waveguides, flanges and
gaskets must be secured. Never operate the device without a
microwave energy absorbing load attached. Never look into an
open waveguide or antenna while the device is energized.
Never operate the oven until the following points are ensured.
(A) The door is tightly closed.
(B) The door brackets and hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) There is not any other visible damage with the oven.
Servicing and repair work must be carried out only by trained
service engineers.
All the parts marked "*" on parts list are used at voltages more than
250V.
Removal of the outer wrap gives access to potentials above 250V.
All the parts marked "∆" on parts list may cause undue microwave
exposure, by themselves, or when they are damaged, loosened or
removed.
Never operate the Grill and/ or Bottom heater with the oven
outer cabinet removed. (Because air flow is eliminated, and the
excess heat generated on adjacent components). It can cause
permanent damage or a fire.
SHARP CORPORATION
OSAKA, JAPAN
WARNING
WARNING
SERVICING
PRODUCT SPECIFICATIONS
GENERAL INFORMATION
APPEARANCE VIEW
OPERATING SEQUENCE
FUNCTION OF IMPORTANT
COMPONENTS
TROUBLESHOOTING GUIDE
AND TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
MICROWAVE MEASUREMENT
WIRING DIAGRAM
PARTS LIST
1

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Summary of Contents for Sharp R-772WM

  • Page 1 AND BOTTOM GRILLS R-772(W)M/ R-772(G)M GENERAL INFORMATION GENERAL IMPORTANT INFORMATION This Manual has been prepared to provide Sharp Corp. Service APPEARANCE VIEW 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 2: Warning To Service Personnel

    If the water remains Sharp recommend that wherever possible fault-finding is cold carry out 3D checks and re-examine the connections to carried out with the supply disconnected. It may in, some the component being tested.

  • Page 3: Product Description

    PRODUCT DESCRIPTION SPECIFICATION ITEM DESCRIPTION Power Requirements 230 - 240 Volts / 50 Hertz / Single phase, 3 wire earthed Power Consumption Microwave cooking 1.6 kW Approx. 7.2 A Oven cooking 1.5 kW Approx. 6.5 A Top Grill mode ...... 1.05 kW Approx.

  • Page 4: Appearance View

    APPEARANCE VIEW OVEN 8. Grill heating element 1. Control panel (Bottom Grill) 2. Oven lamp 9. Door seals and sealing surfaces 3. Grill heating element (Top Grill) 10.Ventilation openings 4. Door opening button 11.Outer cabinet 5. Waveguide cover 12.Power supply cord 6.

  • Page 5: Operation Sequence

    OPERATION SEQUENCE OFF CONDITION The circuit to the high voltage transformer is cut off when the contacts of relay RY2, and the contacts (COM-NO) of Closing the door activates the monitored latch switch and the monitored latch switch and monitor switch are made the stop switch.
  • Page 6 OPERATION SEQUENCE ing the TIME keys and touh the GRILL key once. When the turning the top and bottom heating elements on and STARTkey is touched, the following operations occur: off, as needed to maintain the selected pre-heat temperature. The ovenwill shut-down completely af- 1.
  • Page 7 OPERATION SEQUENCE down to zero. LIMITATIONS OF POWER OUTPUT IN MANUAL 2. The oven lamp, cooling fan motor and turntable motor OPERATION are energized. After the same cooking mode is carried out for more than 3. The relay RY4 is energized and the main supply the specified cooking time, the power output is automati- voltage is applied to the bottom grill heating element.

  • Page 8: Function Of Important Components

    FUNCTION OF IMPORTANT COMPONENTS DOOR OPEN MECHANISM FUSE 15A 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 blows to prevent an electric shock of fire lever is pushes lower latch head on the door upward.

  • Page 9: Troubleshooting Guide

    FUNCTION OF IMPORTANT COMPONENTS voltage doubler circuit. When the oven cooking time reaches “0”, the heating 3. D2 of the rectifier is shorted. elements are de-energized and the oven shuts off. At that 4. The large electric currents flow through the high volt- time if the cavity air temperature has rised above120˚C, the fan motor remains rotating.
  • Page 10 TEST PROCEDURE A B C D E E E F G G H H I J K L L M N O O O O O O P POSSIBLE CAUSE DEFECTIVE PARTS PROBLEM CONDITION Fuse F8A blows when the door is opened. Home fuse blows when power cord is plugged into wall outlet.

  • Page 11: Test Procedures

    The power output of this oven is rated using the method specified by IEC 705. Full details of how to curry out this procedure can be found in the Sharp Technical Training notes which is available from Sharp Parts Centre (part number SERV-LITMW01).
  • Page 12 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER HIGH VOLTAGE TRANSFORMER TEST WARNING: High voltage and large currents are present at the secondary winding and filament winding of the high voltage transformer. It is very dangerous to work near this part when the oven is on. NEVER make any voltage measurements of the high-voltage circuits, including the magnetron filament.
  • Page 13 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER SWITCH TEST CARRY OUT 3D CHECKS. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table. Table: Terminal Connection of Switch Plunger Operation COM to NO COM to NC COM;...
  • Page 14 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER NOISE FILTER TEST CARRY OUT 3D CHECKS. Disconnect the leads from the terminals of noise filter. Using an ohmmeter, check between the terminals as described in the following table. Cx ± 20% Cy ± 20% L (min) 1.0mH 0.22µF...
  • Page 15 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably faulty and should be replaced. CARRY OUT 4R CHECKS. 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 can not be performed with only a voltmeter and ohmmeter.
  • Page 16 TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER RELAY TEST CARRY OUT 3D CHECKS. Remove the outer case and check voltage between Pin Nos. 1 and 3 of the 4 pin connector (E) on the control unit with an A.C. voltmeter. The meter should indicate 230 - 240 volts, if not check oven circuit. Relay Test Check voltage at the relay coil with a D.C.

  • Page 17: Touch Control Panel Assembly

    TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units as circuit. It accompanies a very small error because it shown in the touch control panel circuit. works on commercial frequency. (1) Key Unit 4) ACL (2) Control Unit (The Control unit consists of Power unit A circuit to generate a signal which resets the LSI to the...
  • Page 18 DESCRIPTION OF LSI LSI(IZA965DR) The I/O signal of the LSI(IZA965DR) are detailed in the following table. Pin No. Signal Description Input signal which communicates the door open/close information to LSI. Door closed; "H" level signal. Door opened; "L" level signal. 9-10 AN1-AN0 Terminal not used.
  • Page 19 DESCRIPTION OF LSI LSI(IZA965DR) The I/O signal of the LSI(IZA965DR) are detailed in the following table. Pin No. Signal Description Key strobe signal. Signal applied to touch-key section. A pulse signal is input to P44 - P47 terminal while one of G3 line key on matrix is touched. Key strobe signal.
  • Page 20 DESCRIPTION OF LSI LSI(IZA965DR) The I/O signal of the LSI(IZA965DR) are detailed in the following table. Pin No. Signal Description Terminal not used. Fan motor driving signal. To turn on and off the fan motor relay RY6. "L" level during cooking, or for 5 minutes after grill cooking or for a while after oven or dual cooking.
  • Page 21 SERVICING 1. Precautions for Handling Electronic Components 6) Run the oven and check all functions. This unit uses CMOS LSI in the integral part of the circuits. On some models, the power supply cord between the When handling these parts, the following precautions touch control panel and the oven itself is so short that should be strictly followed.

  • Page 22: Component Replacement And Adjustment Procedure

    Oven lamp, Magnetron, High voltage transformer To prevent an electric shock, take the following and Oven cavity. precautions. 3) Sharp edge: 1. Before wiring, Bottom plate, Oven cavity, Weveguide flange, 1) Disconnect the power supply. Chassis support and other metallic plate.

  • Page 23: High Voltage Transformer Removal

    COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 4. Remove one (1) screw holding earth side terminal of 10.Disconnect the high voltage rectifier assembly from the the high voltage rectifier assembly. high voltage wire B. 5. Remove one (1) screw holding fan duct to the oven 11.Now, the high voltage rectifier assembly and the high cavity rear plate.

  • Page 24: Installation

    Re-install 4. Cut the four (4) bridges holding the turntable motor 1. Remove the any sharp edges on the turntable motor cover to the base plate with cutting pliers as shown in cover and the base plate with the cutting pliers.
  • Page 25 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ® POSITIVE LOCK CONNECTOR REMOVAL Terminal 1. CARRY OUT 3D CHECKS. Positive lock® connector ® 2. Push the lever of positive lock connector. ® 3. Pull down on the positive lock connector. Push Lever CAUTION: WHEN YOU (SERVICE ENGNEERS) CON- ®...

  • Page 26: Monitored Latch Switch, Monitor Switch And Stop Switch Removal

    COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE the bottom heating element. 4. Remove the two (2) nuts holding the bottom heating 6. Remove the bottom heating element from the oven element to the oven cavity. cavity . 5. Remove the heater cover and the heater packing from MONITORED LATCH SWITCH, MONITOR SWITCH AND STOP SWITCH REMOVAL 1.
  • Page 27 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 6. Locate door panel hinge pins into cavity hinge location holes. 7. Re-install choke cover to door panel by clipping into position. Note: After any service to the door; (A) Make sure that the monitor switch, monitored latch switch and stop switch are operating prop- erly.

  • Page 28: Microwave Measurement

    MICROWAVE MEASUREMENT PROCEDURE After any repair, the microwave oven must be checked for microwave leakage to ensure continued safe operation. 1. Place the beaker containing the water load in the oven BS EN 60335-2-25 specifies that the maximum permitted cavity at the centre of the turntable. The placing of this leakage with a load of 275 ml is 50 W/m (equivalent to 5 standard load in the oven is important, not only to...
  • Page 29 SCHEMATIC Note: SCHEMATIC AC CORD CONNECTION NOTE: CONDITION OF OVEN BRN : BROWN 1. DOOR CLOSED. BLU : BLUE 2. PLUGGED IN OVEN. G-Y : GREEN AND YELLOW STRIPE 3. NOTHING APPEARS ON DISPLAY. /15 : SECTIONAL AREA OF 1.5mm MIN.
  • Page 30 230 - 240V ~ 50Hz 230 - 240V ~ 50Hz 230 - 240V ~ 50Hz BLU/15 BRN/15 BLU/15 BRN/15 BLU/15 BRN/15 G-Y/15 G-Y/15 G-Y/15 NEUTRAL LIVE NEUTRAL LIVE NEUTRAL LIVE EARTH EARTH EARTH 0.22µ/250V 0.22µ/250V 0.22µ/250V FUSE 15A FUSE 15A FUSE 15A 10M/ 0.5W 10M/ 0.5W...
  • Page 31 SCHEMATIC SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME ENTERED. 3. TOP & BOTTOM GRILL MODE SELECTED. 4. STRAT KEY TOUCHED. FUSE F8A NOISE FILTER THERMAL CUT-OUT OVEN THERMAL (SW3)STOP SWITCH THERMISTOR CUT-OUT (SW1)MONITORED LATCH SWITCH ASYMMETRIC (SW2)MONITOR RECTIFIER SWITCH...
  • Page 32 SCHEMATIC SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. 2. COOKING TIME ENTERED. 3. DUAL GRILL KEY TOUCHED ONCE. 4. MICROWAVE POWER LEVEL ENTERED. 5. STRAT KEY TOUCHED. FUSE F8A NOISE FILTER THERMAL CUT-OUT OVEN THERMAL (SW3)STOP SWITCH THERMISTOR CUT-OUT ASYMMETRIC (SW1)MONITORED LATCH SWITCH (SW2)MONITOR...
  • Page 33 THERMISTOR CN-C POWER SUPPLY CORD TOP GRILL HEATING ELEMENT G—Y N.C. CONTROL PANEL MONITOR SWITCH OVEN THERMAL OVEN LAMP IC-1 CUT-OUT MONITORED LATCH CN-G CN-1 SWITCH CN-B CN-B F 8 A WH-1 NOISE FILTER CN-C MG. THERMAL CUT-OUT CN-E CN-A STOP BOTTOM MOTOR...

  • Page 34: Power Unit Circuit

    POWER UNIT CIRCUIT OVEN S1NB10 WH1-4 THERMISTOR WH1-3 – – R4 510 1w WH1-6 R3 510 1w R5 3.3k WH1-9 BUZZER AC230 - 240V 50Hz WH1-10 WH1-5 POWER WH1-11 CONTROL FAN MOTOR WH1-8 WH1-7 R6 130 1w OVEN LAMP TURNTABLE MOTOR BOTTOM WH1-12...

  • Page 35: Cpu Unit Circuit

    CPU UNIT CIRCUIT...

  • Page 36: Printed Wiring Board

    PRINTED WIRING BOARD VRS1 POWER CONT Figure S-4. Printed Wiring Board of Power Unit...

  • Page 37: Parts List

    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. § DESCRIPTION Q'TY CODE ELECTRIC PARTS 1- 1 FPWBFA309WRE2...
  • Page 38 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. § DESCRIPTION Q'TY CODE OVEN PARTS ∆...

  • Page 39: Oven Parts

    OVEN PARTS OVEN PARTS 7-12 7-12 4-14 7-12 7-13 7-12 7-12 4-18 4-26 1-11 7-13 1-10 4-18 1-17 7-12 7-15 1-20 4-27 7-15 4-16 7-12 1-12 7-12 1-19 7-14 4-11 4-23 4-17 1-16 7-10 4-22 1-15 4-10 4-13 7-12 1-13 4-12 4-15 1-14...

  • Page 40: Control Panel Parts

    CONTROL PANEL PARTS 3-3-1 3-3-2 3-3-3 3-3-4 DOOR PARTS...

  • Page 41: Miscellaneous/Packing And Accessories

    MISCELLANEOUS/PACKING AND ACCESSORIES MISCELLANEOUS Actual wire harness may be different than illustration. PACKING AND ACCESSORIES TOP PAD ASSEMBLY (FPADBA336WRK0) WRAP COVER R-772(W)M: SSAKHA041WRE0 PRINTED MATTER R-772(G)M: SSAKHA047WRE0 OUTER WRAP COVER (for R-772(G)M) (SPADFA353WRE0) RACK DOOR PROTECTION SHEET (SPADPA020WRE0) TURNTABLE TRAY ACCESSORY HOLDER BOTTOM PAD ASSEMBLY (SPADPA015URE0)
  • Page 42 NOTES...
  • Page 43 '99 SHARP CORP. (8S1.31E) Printed in U.K.

This manual is also suitable for:

R-772gmR-772mR772m-003

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