Sharp R-420CK Service Manual Download Page 25

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R-420CK
R-420CW

P25

OUT

Magnetron high-voltage circuit driving signal.

To turn on and off the cook relay (RY2). The
signals holds "L" level during microwave cooking
and "H" level while not cooking. In other cooking
modes (variable cooking) the signal turns to "H"
level and "L" level in repetition according to the
power level.

(ON and OFF times for other power level.)

25-26

P26-P27

OUT

Terminal not used.

27-29

P30-P32

OUT

Terminal not used.

30-34

P33-P37

OUT

Used for initial balancing of the bridge circuit (absolute humidity sensor).

CVCC

Connected to GND.

VSS

Power source voltage: -5.0V.
The power source voltage to the LSI is input to VSS terminal. Connected to VC

37-38

V3-V2

Power source voltage input terminal.

Standard voltage for LCD

37-38

V3-V2

Power source voltage input terminal.

Standard voltage for LCD

39-40

V1-V0

Power source voltage input terminal.

Standard voltage for LCD. Connected to GND.

VCC

Power source voltage: GND (0V).
The power source voltage to drive the LSI is input to VCC terminal.

COM4

OUT

Terminal not used.

COM3

OUT

Common data signal: COM2.
Connected to LCD signal COM2.

COM2

OUT

Common data signal: COM1.
Connected to LCD signal COM1.

COM1

OUT

Common data signal: COM0.
Connected to LCD signal COM0.

46-54

SEG21-SEG0

OUT

Segment data signal.
Connected to LCD.
The relation between signals are as follows:
LSI signal (Pin No.)

LCD (Pin No.)

LSI signal (Pin No.)

LCD (Pin No.)

SEG 1 (46) ............................... SEG0

SEG 20 (65) ......................... SEG 18

SEG 2 (47) ............................... SEG1

SEG 21 (66) ......................... SEG 19

SEG 3 (48) ............................... SEG2

SEG 22 (67) ......................... SEG 20

SEG 4 (49) ............................... SEG3

SEG 23 (68) ......................... SEG 21

SEG 5 (50) ............................... SEG4

SEG 24 (69) ......................... SEG 22

SEG 6 (51) ............................... SEG5

SEG 25 (70) ......................... SEG 23

SEG 7 (52) ............................... SEG6

SEG 26 (71) ......................... SEG 24

SEG 8 (53) ............................... SEG7

SEG 27 (72) ......................... SEG 25

SEG 9 (54) ............................... SEG8

SEG 28 (73) ......................... SEG 26

SEG 11 (56) ............................... SEG9

SEG 29 (74) ......................... SEG 27

SEG 12 (57) ............................. SEG10

SEG 30 (75) ......................... SEG 28

SEG 13 (58) ............................. SEG11

SEG 31 (76) ......................... SEG 29

SEG 14 (59) ............................. SEG12

SEG 32 (77) ......................... SEG 30

SEG 15 (60) ............................. SEG13

SEG 33 (78) ......................... SEG 31

SEG 16 (61) ............................. SEG14

SEG 34 (79) ........................ SEG 32

SEG 17 (62) ............................. SEG15

SEG 35 (80) ......................... SEG 33

SEG 18 (63) ............................. SEG16

SEG 36 (81) ......................... SEG 34

SEG 19 (64) ............................. SEG17

SEG 37 (82) ......................... SEG 35

Pin No.

Signal

I/O

Description

P-HI

H : GND

L : -5V

H : GND

L : -5V

P-70

OFF

24 sec.

8 sec.

Summary of Contents for R-420CK

Page 1: ...LE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY INSIDE FRONT COVER BEFORE SERVICING INSIDE FRONT COVER WARNING TO SERVICE PERSONNEL 1 MICROWAVE MEASUREMENT PROCEDURE 2 FOREWORD AND WARNING 3 PRODUCT SPECIFICATIONS 4 GENERAL INFORMATION 5 OPERATION 6 TROUBLESHOOTING GUIDE 10 TEST PROCEDURE 12 TOUCH CONTROL PANEL 21 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 25 PICTORIAL DIAGRAM 33 POWER UNIT CIRCUIT ...

Page 2: ...tion and transmission systems shall be repaired replaced or adjusted by procedures described in this manual before the oven is released to the owner e A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner BEFORE SERVICING Before servicing an operative unit perform a microwave emission check as per the Mic...

Page 3: ...acitor 4 Disconnect the leads to the primary of the power transformer 5 Ensure that the leads remain isolated from other components and oven chassis by using insulation tape 6 After that procedure reconnect the power supply cord When the testing is completed 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Reconnec...

Page 4: ...he center of the oven cavity The water container shall be a low form of 600 ml 20 oz beaker with an inside diameter of approx 8 5 cm 3 1 2 in and made of an electrically nonconductive material such as glass or plastic The placing of this standard load in the oven is important not only to protect the oven but also to insure that any leakage is measured accurately 4 Set the cooking control on Full P...

Page 5: ... is not damaged D The door is not deformed or warped E There is no other visible damage with the oven Servicing and repair work must be carried out only by trained service personnel DANGER Certaininitialpartsareintentionallynotgroundedandpresent a risk of electrical shock only during servicing Service personnel Do not contact the following parts while the appliance is energized HighVoltageCapacito...

Page 6: ...on pads Power Level pad Timer Clock pad Stop Clear pad START pad Oven Cavity Light Yes Safety Standard UL Listed FCC Authorized DHHS Rules CFR Title 21 Chapter 1 Subchapter J SPECIFICATION GENERAL INFORMATION GROUNDING INSTRUCTIONS This oven is equipped with a three prong grounding plug It must be plugged into a wall receptacle that is properly installed and grounded in accordance with the Nationa...

Page 7: ...CUT OR RE MOVE THE ROUND GROUNDING PRONG FROM THIS PLUG OVEN DIAGRAM 1 One touch door open button Push to open door 2 Door latches The oven will not operate unless the door is securely closed 3 Removable turntable support 4 Removable turntable The turntable will rotate clockwise or counterclockwise 5 Oven lamp It will light when oven is operating or door is opened 6 Oven door with see through wind...

Page 8: ...ble motor the cooling fan motor and the high voltage components are de energized the oven lamp remains on and the digital read out displays the time still remaining in the cook cycle when the door was opened 7 The monitor switch electrically monitors the operation of the secondary interlock switch and primary interlock relayandismechanicallyassociatedwiththedoorsothat it will function in the follo...

Page 9: ...e of the SENSOR pads NOTE The oven should not be operated on sensor immediatly after plugging in the unit Wait two minutes before cooking on SENSOR 2 The coil of shut off relay RY 1 is energized the turntablemotorareturnedon butthepowertransformer is not turned on 3 After about 16 seconds the cook relay RY 2 is energized The power transformer is turned on microwaveenergyisproducedandfirststageisst...

Page 10: ... B1 B2 GRN POWER TRANSFORMER MONITOR FUSE 20A MAGNETRON TEMP FUSE CAPACITOR 1 0µF AC 2300V AH SENSOR SCHEMATIC 2 CLOCK APPEARS ON DISPLAY 3 VARIABLE COOKING CONTROL HIGH 2 COOKING TIME PROGRAMMED 1 DOOR CLOSED NOTE CONDITION OF OVEN 4 START PAD TOUCHED 120V AC 60 Hz OVEN LAMP TURN TABLE MOTOR FAN MOTOR MONITOR SWITCH H V RECTIFIER MAGNETRON SECONDARY INTERLOCK SWITCH TTM OL FM MONITOR FUSE 20A CAV...

Page 11: ...A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH PRIMARY INTERLOCK RELAY RY2 RELAY RY1 SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OP ERATION REFERTOCHAPTER TESTPRO CEDURE NOTE MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY TURNTABLE MOTOR The turntable motor rotates the turntable located on the bottom of the oven cavity so that the foods on the turntable cook evenly dur...

Page 12: ...S BA016 KIT as an assembly IMPORTANT Whenever troubleshooting is performed with the power supply cord disconnected It may in some cases be necessary to connect the power supply cord after the outer case has been removed in this event 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Disconnect the leads to the prima...

Page 13: ...ycle Oven goes into a cook cycle but extremely uneven heating is produced in oven load food Oven does not cook properly when programmed for Cooking Power 5 mode Operates properly on Cooking Power 10 HIGH mode Oven goes into COMPU DEFROST but food is not defrosted well AH sensor does not end during sensor cooking condition Oven does not shut off after a cup of water is boiling by sensor cooking Ove...

Page 14: ...TREME CAUTION SHOULD BE OBSERVED Power output of the magnetron can be measured by performing a water temperature rise test This test shouldonlybeusedifabovetestsdonotindicateafaultymagnetronandthereisnodefectinthefollowing componentsorwiring siliconrectifier highvoltagecapacitorandpowertransformer Thistestwillrequire a 16 ounce 453cc measuring cup and an accurate mercury thermometer or thermocoupl...

Page 15: ...he cooling fan and air guide 5 Reconnect all leads removed from components during testing 6 Reinstall the outer case cabinet 7 Reconnect the power supply cord after the outer case is installed 8 Run the oven and check all functions MAGNETRON TEMPERATURE FUSE TEST 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 A c...

Page 16: ...terlock switch 5 Reconnect all leads removed from components during testing 6 Reinstall the outer case cabinet 7 Reconnect the power supply cord after the outer case is installed 8 Run the oven and check all functions PRIMARY INTERLOCK SYSTEM TEST DOOR SENSING SWITCH 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4...

Page 17: ...rowave 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 also the Control Unit is divided into two units LSI Unit and Power Unit and troubleshooting by unit replacement is described according to the symptoms indicated Before testing 1 Disconnect the power su...

Page 18: ...ck does not operate properly c Cooking is not possible When testing is completed 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Reconnect all leads removed from components during testing 5 Re install the outer case cabinet 6 Reconnect the power supply cord after the outer case is installed 7 Run the oven and chec...

Page 19: ...should indicate 120 volts if not check oven circuit 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 If diode is good control unit is defective RELAY SYMBOL OPERATIONAL VOLTAGE CONNE...

Page 20: ... after the outer case is installed 9 Run the oven and check all functions 2 Followthetroubleshootingguidegivenbelow ifindicatordoesnotlightupafterabovecheckandrepairs are finished 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Disconnect the leads to the primary of the power transformer 5 Ensure that these leads ...

Page 21: ... oz of tap water in 1000 millilitres measuring cup 3 Place the container on the center of tray in the oven cavity 4 Close the door 5 Touch REHEAT or REHEAT SENSOR pad once Now the oven is in the sensor cooking condition and SENSOR REHEAT will appear in the display 6 The oven will operate for the first 16 seconds without generating microwave energy NOTE ERROR will appear if the door is opened or ST...

Page 22: ...ds push plunger of select switch for more than 3 seconds This condition is same as judgement by AH sensor 9 4 After approximately 3 seconds the display shows xx xx which is remaining cooking time and the display count down If the above is not the case the control unit is probably defective If the above is proper the AH sensor is probably defective 10 Disconnect the power supply cord and then remov...

Page 23: ... Circuit The buzzer is responsive to signals from the LSI to emit audiblesounds keytouchsoundandcompletionsound 6 Synchronizing Signal Circuit The power 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 7 Door Sensing Switch A switch to tell the LSI if the door is open o...

Page 24: ...is touched 12 X1 IN Connected to GND 13 X2 OUT Terminal not used 14 VSS IN Power source voltage 5 0V VC voltage of power source circuit input 15 OSC2 OUT Internal clock oscillation frequency control output Output to control oscillation input of OSC2 16 OSC1 IN Internal clock oscillation frequency input setting The internal clock frequency is set by inserting the ceramic filter oscillation circuit ...

Page 25: ...GND 0V The power source voltage to drive the LSI is input to VCC terminal 42 COM4 OUT Terminal not used 43 COM3 OUT Common data signal COM2 Connected to LCD signal COM2 44 COM2 OUT Common data signal COM1 Connected to LCD signal COM1 45 COM1 OUT Common data signal COM0 Connected to LCD signal COM0 46 54 SEG21 SEG0 OUT Segment data signal Connected to LCD The relation between signals are as follows...

Page 26: ...put is an analoginputterminalfromtheAHsensorcircuit andconnectedtotheA Dconverter built into the LSI 92 AN1 IN AH sensor input This input is an anlage input terminal from the AH sensor circuit and connected to the A D converter built into the LSI 93 AN2 IN To input signal which communicates the door open close information to LSI Door close H level signal 0V Door open L level signal 5V 93 83 85 AN3...

Page 27: ...king of the unit When the unit is set in the sensor cooking mode 16 seconds clearing cycle occurs then the detector circuit starts to function and the LSI observes the initial voltage available at its AN1 terminal With this voltage given the switches SW1 to SW5 in the LSI are turned on in such a way as to change the resistance values in parallel with R107 R111 of IC2 Changing the resistance value ...

Page 28: ... the oven door being closed Connect an external power source to the power input terminal of the touch control panel then it is possible to check and repair the controls of the touch control panel it is also possible to check the sensor related controls of the touch control panel by using the dummy resistor s 3 Servicing Tools Toolsrequiredtoservicethetouchcontrolpanelassembly 1 Soldering iron 30W ...

Page 29: ...NG 1 Disconnect the power supply cord 2 Make sure that a definite click can be heard when the microwave oven door is unlatched Hold the door in a closed position with one hand then push the door open button with the other this causes the latch leads to rise it is then possible to hear a click as the door switches operate 3 Visuallycheckthedoorandcavityfaceplatefordamage dents cracks signs of arcin...

Page 30: ... lead short one of the power transformer from the high voltage capacitor 7 Remove one 1 screw holding capacitor holder with the high voltage rectifier to the base plate 8 Disconnect rectifier terminal from capacitor High voltage rectifier assembly is now free 9 Remove capacitor holder Capacitor is now free CAUTION WHEN REPLACING HIGH VOLTAGE RECTI FIER AND HIGH VOLTAGE CAPACITOR GROUND SIDE TERMIN...

Page 31: ...ft cloth not to scratch LSI UNIT NOTE Handle the LSI unit carefully so that there is no excessive force applied to the ribbon connection LSI unit 1 Disconnect the power supply cord 2 Removeturntableandturntablesupportfromovencavity 3 Lay the oven on it s backside Remove the turntable motor cover by snipping off the material in four corners 4 Where the corners have been snipped off bend corner area...

Page 32: ...he bracket may be disfigured Make sure that the fan blade rotates smooth after installation Make sure that the axis of the shaft is not slanted 5 Install the fan motor to the oven cavity back plate with the two 2 screws 6 Connect the wire leads to the fan motor referring to the pictorial diagram Side View Rear View 1 Disconnect the power supply cord and remove outer case 2 Open the door and block ...

Page 33: ...the door should be less than 0 5mm 2 The door sensing switch and secondary interlock switch interrupt the circuit before the door can be opened 3 Monitor switch contacts close when door is opened 4 Re install outer case and check for microwave leakage around door with an approved microwave survey meter Refer to Microwave Measurement Procedure DOOR REPLACEMENT REMOVAL 1 Disconnect the power supply ...

Page 34: ...ressed toward cavity face plate 4 Check for microwave leakage around door with an approvedmicrowavesurveymeter RefertoMicrowave Measurement Procedure Note The door on a microwave oven is designed to act as an electronic seal preventing the leakage of microwave energy from oven cavity during cook cycle Thisfunctiondoesnotrequirethatdoorbeair tight moisture condensation tight or light tight Therefor...

Page 35: ...ght socket POWER TRANSFORMER COM NO NOTE The neutral WHT GRY wire must be connected to the terminal with N mark on the power supply cord RED WHT BRN RED WHT WHT ORG WHT RED BLK RED BLU PNK GRN GRN to Oven cavity WHT WHT RED BLK WHT WHT BLUE MARK WHT RED WHT CAVITY TEMP FUSE MAGNETRON TEMP FUSE FAN MOTOR MONITOR FUSE HOLDER RED RED WHT 1 WHT GRY WHT ORG BLU GRN ORG ORG RY2 RY1 PRIMARY INTERLOCK REL...

Page 36: ...34 R 420CK R 420CW 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 2 Power Unit Circuit ...

Page 37: ...35 R 420CK R 420CW 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 CPU Unit Circuit For R 420CK CW ...

Page 38: ...36 R 420CK R 420CW 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 5 Printed Wiring Board of Power Unit ...

Page 39: ...B QCNCMA275DRE0 J 2 pin connector CN B 1 AB 3 1C FW VZB146MRE0 M 12Pin wire harness CN C 1 AG C1 RC KZA087DRE0 J Capacitor 0 1 uF 50V 1 AA C2 VCEAB31VW108M J Capacitor 1000 uF 35V 1 AF C3 RC KZA087DRE0 J Capacitor 0 1 uF 50V 1 AA C4 5 VCEAB31VW106M J Capacitor 10 uF 35V 1 AF D1 4 VHD11ES1 1 J Diode 11ES1 4 AB D5 8 VHD1SS270A 1 J Diode 1SS270ATA 4 AA Q1 2 VS2SB1238 3 J Transistor 2SB1238 2 AA Q3 VS...

Page 40: ...CW 1 AM MISCELLANEOUS 6 1 FW VZB125MRE0 M Stop switch harnnes 1 AF 6 2 FW VZB168MRE0 M Main wire harnnes 1 AU 6 3 QW QZB016MRE0 M High voltage wire A 1 AC 6 4 FROLPB025MRK0 M Turntable support 1 AN 6 5 NTNT A095WRE0 M Turntable tray 1 AM 6 6 TCAUAB037MRR0 M Monitor caution label 1 AA 6 7 TCAUAB038MRR0 M DHHS Screw caution label 1 AB 6 8 TINSEB205MRR0 M Operation manual 1 AD SCREWS NUTS AND WASHERS...

Page 41: ... C D E F G H OVEN AND CABINET PARTS 2 3 4 7 6 7 1 5 4 6 4 8 4 9 6 5 6 4 2 1 7 6 1 12 4 10 7 2 7 2 7 5 4 3 1 13 7 3 7 6 1 9 7 8 7 8 4 2 7 5 1 11 1 3 1 4 7 4 1 8 1 8 4 4 7 1 4 1 1 1 1 2 2 2 2 2 2 2 2 2 7 5 7 5 4 12 7 5 6 6 1 7 1 6 4 5 1 14 7 7 7 7 7 9 7 9 7 10 4 13 ...

Page 42: ...2 3 6 4 5 1 2 3 A B C D E F G H A B C D E F G H CONTROL PANEL PARTS 5 1 5 1 2 5 1 1 5 3 5 4 5 5 5 2 Actual wire harness may be different from illustration 6 3 6 2 6 1 DOOR PARTS MISCELLANEOUS 3 5 3 2 3 2 1 3 4 3 3 3 2 2 3 2 3 3 1 ...

Page 43: ...CESSORIES DOOR PROTECTION SHEET PLASTIC BAG PACKING CASE TOP PAD ASSEMBLY INTO THE OVEN CAVITY 6 5 TURNTABLE TRAY 6 4 TURNTABLE SUPPORT 6 8 OPERATION MANUAL TRAY PACK SPADPB038MRE0 BOTTOM PAD ASSEMBLY TRAY HOLDER Non replaceable items ...

Page 44: ...9 BY SHARP CORPORATION ALL RIGHTS RESERVED No part of this publication may be repro duced stored in retrieval systems or trans mitted in any form or by any means elec tronic mechanical photocopying record ing or otherwise without prior written per mission of the publisher ...

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