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R-7H55

SHARP CORPORATION

SERVICE MANUAL

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

CONVECTION

MICROWAVE OVEN

MODEL

R-7H55

Page

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

S6417R7H55PHR

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Summary of Contents for R-7H55

Page 1: ...CROWAVE OVEN MODEL R 7H55 Page 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 ...

Page 2: ...R 7H55 ...

Page 3: ...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 dam aged loosened or removed TEST PROC...

Page 4: ...ower for Variable Cooking Repetition Rate HIGH Full power throughout the cooking time MEDIUM HIGH approx 70 of FULL Power MEDIUM approx 50 of FULL Power MEDIUM LOW approx 30 of FULL Power LOW approx 10 of FULL Power Convection Temperature for Variable Cooking CONVECTION 40 to 250 C Temp control LOW MIX 180 C with 10 of microwave power HIGH MIX 200 C with 30 of microwave power GRILL 250 C Preheat S...

Page 5: ...e or to select the Auto Cook menus 12 STOP CLEAR PAD Press to clear during programming Press once to stop operation of oven during cooking press twice to cancel cooking programme 13 AUTO START CLOCK PAD Press to select clock or Auto Start time 14 INSTANT COOK START PAD Press once to cook for 1 minute at HIGH or increase by 1 minute multiples each time this pad is pressed during cooking condition P...

Page 6: ...he circuits to the power transformer and turntable motor are cut off when the 1st latch switch and 2nd latch switch are made open The fan motor is cut off when the stop switch is made open The oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted because the relay RY1 stays closed Shown in the display is the remaining time 6 MONITOR SWITCH CIRCUIT The mo...

Page 7: ...closing the damper switch contacts which send a signal to the control unit de energizing shut off relay RY6 MIX COOKING CONDITION Program desired cooking time and the LOW MIX or HIGH MIX and temperature When the START pad is touched the following operations occur 1 The numbers of the digital readout start the count down to zero 2 The shut off relay RY1 RY5 RY4 energized turning on the oven lamp tu...

Page 8: ...dure is repeated If the difference between the first voltage measured in step 1 and the voltage measured when the procedure is repeated step 2 is greater than 300mV the LSI makes the judgment that there is a fire in the oven cavity and will switch off the relays to the power transformer fan motor and convec tion motor The LSI also stops counting down and closes the damper door so that no fresh air...

Page 9: ...he voltage doubler circuit 3 D2 of the rectifier is shorted 4 The large electric currents flow through the high voltage winding of the power transformer 5 The large electric currents beyond M8A flow through the primary winding of the power transformer 6 The fuse M8A blows by the large electric currents 7 The power supply to the all electrical parts are cut off FUSE M8A 1 ThefuseM8Ablowswhenthecont...

Page 10: ...ized When the temperature inside the oven cavity drops below the selected temperature the heating element is energized again In this way the inside of the oven cavity is maintained at approximately the selected temperature When the convection time reaches 0 the heating element is de energized and the convection fan stops operating and the oven shuts off DAMPER OPEN CLOSE MECHANISM Usually the damp...

Page 11: ...f the high voltage rectifier against the chassis with the use of an insulated screwdriver 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 Ensure that the...

Page 12: ...ute Oven does not go into cook cycle when START pad is touched Low or no power is produced during micro wave cooking The food is heated incom pletely or not heated at all Extremely uneven heating is produced in oven load food Function of variable cooking does not oper ate properly except HIGH power CONV indicator lights but heating element does not heat Temperature in the oven cavity is lower or h...

Page 13: ...AMP OR SOCKET TOUCH CONTROL PANEL KEY UNIT RELAY RY 1 RELAY RY 2 RELAY RY 3 RELAY RY 4 RELAY RY 5 RELAY RY 6 OPENED WIRE HARNESS SHORTED WIRE HARNESS POWER SUPPLY CORD NO POWER AT WALL OUTLETT MONITOR SESISTOR FOIL PATERN ON PWB OPEN WIRING TO THERMISTOR AH SENSOR ASSEMBLY NOISE FILTER Q ...

Page 14: ...ows P x t 4 187 V x T P W 4 187 x V x T t Our condition for water load is as follows Room temperature around 20 C PowersupplyVoltage Ratedvoltage Water load 1000 g Initial temperature 10 2 C Heating time 49 sec P 85 x T Measuring condition 1 Container The water container must be a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approxima...

Page 15: ...g the magnetron filament CARRY OUT 3D CHECKS Disconnect the leads to the primary winding of the power transformer Disconnect the filament and secondary winding connections from the rest of the HV circuitry Using an ohmmeter set on a low range it is possible to check the continuity of all three windings The following readings should be obtained a Primary winding approx 1 2 Ω b Secondary winding app...

Page 16: ...ally close terminal S C Short O C Open circuit If incorrect readings are obtained make the necessary switch or replace the switch CARRY OUT 4R CHECKS Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table CARRY OUT 3D CHECKS CARRY OUT 3D CHECKS A Isolate the high voltage capacitor from the circuit B Continuity check must be carried out...

Page 17: ... motor CARRY OUT 4R CHECKS Table Thermal cut out Test Temperature of ON condition Temperature of OFF condition Indication ofohmmeter Parts Name closed circuit C open circuit C When room temperature is approx 20 C Thermal cut out 145 C This is not resetable type Above 145 C Closed circuit Thermal cut out 150 C Below130 C Above 150 C Closed circuit Thermal cut out 95 C Below 75 C Above 95 C Closed c...

Page 18: ...onsists 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 In this service manual the touch control panel assembly is divided into two units Control Unit and Key Unit and troubleshooting by replacement is described according to the symptoms indicated 1 Key Unit Note Check k...

Page 19: ... does not respond the above method may be used after clearing the control unit to determine if the control unit or key pad is at fault KEY UNIT G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8 G 9 G 10 G 11 G 12 5 SLOW COOK GRILL MICRO WAVE LEVEL EASY DEFROST AUTO COOK MORE LESS STOP CLEAR INSTANT COOK START LOW MIX HIGH MIX SENSOR REHEAT CONVEC 160 C 4 150 C 3 130 C 2 70 C 1 40 C 0 250 C 9 230 C 8 220 C 7 200 C 6...

Page 20: ...should not exceed 95 F 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 Refer to the INSTALLATION Instructions 4 Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity To permit adequate ventilation be sure to install so as not to block th...

Page 21: ...ted to lower portion of control panel 5 Then connect the dummy resistor circuit see fig to the sensor connector of control panel 6 Reconnect the oven to the power supply and check the sensor cook operation proceed as follows 6 1 Touch SENSOR REHEAT pad 6 2 The control panel is in the sensor cooking operation 6 3 After approximately 20 seconds push plunger of select switch This condition is same as...

Page 22: ... source synchronizing signal is available in order to compose a basic standard time in the clock circuit It accompanies a very small error because it works on commercial frequency 4 ACL Circuit A circuit to generate a signals which resets the LSI to the initial state when power is supplied 5 Buzzer Circuit The buzzer is responsive to signals from the LSI to emit noticingsounds keytouchsoundandcomp...

Page 23: ...H MED MED LOW LOW the signal turns to H level and L level in repetition according to the power level 9 R01 IN Input signal which communicates the door open close information to LSI Door closed H level signal Door opened L level signal 10 R02 IN Input signal which communicates the damper open close information to LSI Damper opened H level signal 0V GND Damper closed L level signal 5V VC 11 R03 OUT ...

Page 24: ...o GND 34 INT1 IN Signal synchronized with commercial source frequency 50Hz This is basic timing for time processing of LSI 35 D1 OUT Segment data signals The relation between signals and indicators are as follows Signal segment Signal segment D1 UB R91 f D9 k R92 g R80 a R93 j R81 b R10 p R82 c R11 h R83 d R12 n R90 e R13 LB Refer to the touch control panel circuit for the relationship between sig...

Page 25: ...R20 R23 terminal while one of G 7 line keys on key matrix is touched 51 R83 OUT Segment data signal Signal similar to D1 Key strobe signal Signal applied to touch key section A pulse signal is input to R20 R23 terminal while one of G 8 line keys on key matrix is touched 52 55 R90 R93 OUT Segment data signal Signal similar to D1 56 59 R10 R13 OUT Segment data signal Signal similar to D1 60 R20 IN S...

Page 26: ...itches SW1 to SW5 in the LSI are turned on in such a way as to change the resistance values in parallel with R1 Changing the resistance values results in that there is the same potential at both F 3 terminal of the absolute humidity sensor and AN2 terminal of the LSI The voltage of AN1 terminal will indicate about 2 5V This initial balancing is set up about 16 seconds after the unit is put in the ...

Page 27: ...olytic capacitors etc to PWB making sure that all connections are tight 5 Be sure to use specified components where high precision is required 1 Precautions for Handling Electronic Components This unit uses CMOS LSI in the integral part of the circuits When handling these parts the following precautions should be strictly followed CMOS LSI have extremely high impedance at its input and output term...

Page 28: ...en with the outer case removed N B Step 1 2 and 6 from the basis of the 3D checks MAGNETRON REMOVAL 1 CARRY OUT 3D CHECKS 2 Disconnectfilamentleadoftransformerfrommagnetron 3 Disconnect high voltage wire lead from magnetron 4 Remove two 2 screws holding the chassis support to the oven cavity face plate and the rear cabinet 5 Remove one 1 screw holding the chassis support to the magnetron 6 Careful...

Page 29: ... a pair of groove joint pliers CAUTION Make sure that any pieces do not enter the gap between the rotor and the stator of the fan motor because the rotor is easily shaven by pliers and metal pieces may be produced Do not touch the pliers to the coil of the fan motor because the coil may be cut or injured Do not disfigure the bracket by touching with the pliers 2 Remove the fan blade from the shaft...

Page 30: ...the oven from power supply 2 Remove the turntable tray and the turntable support out of the oven cavity 3 Turn the oven upside down and remove one 1 screw holding the turntable motor cover to the base plate and take off the turntable motor cover 4 Disconnect wire lead from the turntable motor 5 Remove the two 2 screws holding the turntable motor to the thermal cover bottom 6 Now turntable motor is...

Page 31: ...e C 2 Power supply cord Noise filter Power supply cord Brown wire Blue wire Cord anchorage POWER SUPPLY CORD REPLACEMENT Removal 1 CARRY OUT 3D CHECKS 2 Disconnect the brown wire and blue wire of the power supply cord from the noise filter 3 Removethesingle 1 screwholdingthecordanchorages to the oven cavity 4 Remove the power supply cord from the oven Re install 1 Insert the power supply cord into...

Page 32: ...onnectovenfrompowersupplyandremoveturntable tray and turntable support from oven cavity 2 Remove the outer case cabinet refer to OUTER CASE CABINET REMOVAL 3 Remove two 2 screws from upper oven hinge 4 Push the open button and open the door slightly 5 Release the upper oven hinge from upper door hinge pin by pulling down the door 6 Release the lower door hinge pin from the lower oven hinge by pull...

Page 33: ...he gap between the choke cover and corner portion of door panel as shown Figure C 5 to free engaging parts 3 Lift up choke cover 4 Now choke cover is free from door panel 5 Remove six 6 screws holding the door frame to the gutter for choke cover 6 Remove the door frame with pulling the upper door hinge pin Figure A 1 CUT H V READ WIRES H V RECTIFIER ASYMMETRIC RECTIFIER PROCEDURE FOR SERVICE OF DE...

Page 34: ...crowave ovens must be used for testing Recommended instruments are NARDA 8100 NARDA 8200 HOLADAY HI 1500 SIMPSON 380M 2 Place the oven tray into the oven cavity 3 Place the load of 275 15ml of water initially at 20 5 C in the centre of the oven tray The water container should be a low form of 600 ml beaker with inside diameter of approx 8 5cm and made of an electrically non conductive material suc...

Page 35: ...OM COM COM RY3 RY2 PRIMARY INTERLOCK RELAY RY1 RY6 RY5 RY4 N O N O TURNTABLE MOTOR CONVECTION HEATING ELEMENT 2ND LATCH SWITCH MONITOR SWITCH MONITOR RESISTOR 0 8 20W H V RECTIFIER THERMAL CUT OUT 95 C FAN N O AH SENSOR F3 F2 F1 GRN ASYMMETRIC RECTIFIER THERMAL CUT OUT 145 C MG BRN BLU G Y NEUTRAL LIVE EARTH FUSE M8A L N RESISTOR 680K LINE CROSS CAPACITOR 0 22µ AC 250V noise suppression coil RESIS...

Page 36: ...TOR CONVECTION MOTOR DAMPER MOTOR OVEN LAMP RED A5 A7 A9 COM COM COM RY3 RY2 PRIMARY INTERLOCK RELAY RY1 RY6 RY5 RY4 N O N O TURNTABLE MOTOR CONVECTION HEATING ELEMENT 2ND LATCH SWITCH MONITOR SWITCH MONITOR RESISTOR 0 8 20W H V RECTIFIER THERMAL CUT OUT 95 C FAN 220 V 50Hz N O AH SENSOR F3 F2 F1 GRN ASYMMETRIC RECTIFIER THERMAL CUT OUT 145 C MG BRN BLU G Y NEUTRAL LIVE FUSE M8A L N RESISTOR 680K ...

Page 37: ...2ND LATCH SWITCH NO COM NC COM MONITOR SWITCH STOP SWITCH NO COM H V C A P A C I T O R PNK ORG BRN THERMISTOR PNK PNK GRY GRY WHT YLW DAMPER MOTOR PNK 1 2 3 4 5 6 7 8 9 CN A CN A 1 6 COM RED ORG CN B COM NO DAMPER SWITCH RY2 RY1 RY3 PNK WHT BLK GRN BLK BLK BRN BLK BLK PNK BLK CONTROL PANEL BLK GRY ORG BLK BLK H V WIRE NEUTRAL LIVE THERMAL CUT OUT 95 C FAN WHT WHT WHT THERMAL CUT OUT 145 C MG RED B...

Page 38: ...R63 R70 R71 R00 R72 R01 R02 R03 TEST RESET OSC1 OSC2 GND X1 X2 AVSS AN0 AN1 AN2 AN3 AN4 AN5 AN7 AN8 AN9 AN10 AN11 AVCC AN6 1 5 10 15 20 25 30 32 64 60 55 50 45 40 35 33 R31 1K SP30 R30 3 3K R78 15K Q60 DTC143ES R62 3 0KF R61 130F R50 100 R40 100 R41 5 1K C8 D40 D28 R60 120KF R51 5 1K C40 C50 C60 AH SENSOR OVEN THERMISTOR DAMPER SWITCH DOOR SENSING SWITCH CR70 D78 D77 D76 D75 R77 15K R76 15K R75 15...

Page 39: ...37 R 7H55 6 4 5 1 2 3 6 4 5 1 2 3 A B C D E F G H A B C D E F G H Figure S 3 Printed Wiring Board ...

Page 40: ...l unit 1 BR 3 1A QCNCMA227DRE0 9 pin connector A 1 AC 3 1B QCNCMA267DRE0 6 pin connector B 1 AC 3 1C QCNCWA030DRE0 12 pin connector G 1 AF 3 1D QCNCMA237DRE0 3 pin connector F 1 AD 3 1E RV KXA063DRE0 Fluorescent display tube 1 AZ C1 RC KZA087DRE0 Capacitor 0 1µF 50V 1 AB C2 VCEAB31VW108M Capacitor 1000µF 35V 1 AF C3 VCEAB31EW476M Capacitor 47µF 25V 1 AA C4 VCKYB11EX103N Capacitor 0 01µF 25V 1 AA C...

Page 41: ...QA392WRP0 Convection motor mounting plate 1 AH 4 2 LANGQA393WRP0 Heater mounting plate 2 AD 4 3 LANGTA306WRP0 Thermistor plate 1 AF 4 4 NFANMA045WRP0 Convection fan 1 AD 4 5 NFANMA046WRP0 Reflection fan 1 AD 4 6 PDUC A556WRW0 Convection duct 1 AS 4 7 MHNG A342WRM0 Lower oven hinge 1 AK 4 8 PCUSGA404WRP0 Cushion 1 AA 4 9 PSKR A273WRP0 Reflector A 1 AF 4 10 PSKR A274WRP0 Reflector B 1 AF 4 11 PSKR A...

Page 42: ...ltage wire A 1 AK 6 10 LBNDKA080WRE0 Wire holder B 1 AD 6 11 LHLDWA011WRE0 Purse lock M 1 AB 6 12 TCAUHA055WRR0 Caution label 1 AF 6 13 TLABPA032WRR0 Earth label 1 AG 6 14 FW VZB308WRE0 Main harness 1 BA 6 15 QW VZA125WRE0 Earth wire 1 AK SCREWS NUTS AND WASHERS 7 1 XBTSD40P05000 Screw 4mm x 5mm 2 AA 7 2 XBTWW40P06000 Screw 4mm x 6 mm 2 AA 7 3 XCBWW30P06000 Screw 3mm x 6mm 8 AA 7 4 XCPSD30P06000 S...

Page 43: ...16 4 18 1 16 4 34 7 11 4 44 4 38 4 14 7 16 x16 1 1 7 3 7 2 4 6 4 2 4 11 7 3 7 3 4 10 7 3 7 3 7 8 4 2 7 3 7 16 4 3 7 3 4 4 7 8 7 6 7 10 4 25 1 2 4 21 1 11 7 13 4 31 7 18 7 26 4 32 1 14 7 12 7 18 7 12 4 39 7 25 1 5 1 6 1 5 4 35 7 16 7 11 7 16 4 13 2 3 x4 7 5 4 22 4 27 1 9 4 23 2 2 7 15 1 8 7 23 4 26 7 21 2 5 7 18 1 17 7 7 4 9 x3 2 1 7 17 7 15 7 11 x3 7 16 6 10 7 25 7 18 1 12 1 21 7 18 7 18 4 8 1 5 1...

Page 44: ...arness may be different from illustrations 6 11 6 13 PACKING AND ACCESSORIES TRAY HOLDER SPADFA340WRE0 TURNTABLE TRAY LOW RACK INSTRUCTION ASSEMBLY TURNTABLE SUPPORT TRAY PAD SPADPA502WRE0 DOOR PROTECTOR SPADPA204WRE0 PACKING CASE SPAKCC346WRE0 WRAP COVER SSAKHA034WRE0 PAD ASSEMBLY CPADBA176WRK0 Not replaceable items HIGH RACK 94SHARP CORP 06K0 07E Printed in Japan 3 1 3 2 3 3 3 4 3 5 3 5 SPAKCC34...

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