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R420LW

12 – 1

R420LW

Service Manual

CHAPTER 12.

CIRCUIT DIAGRAMS

[1] Pictorial Diagram (Figure S-1)

Figure S-1. Pictorial Diagram

HIGH VOLTAGE CAPACITOR

H.V.

ECTIFIER

HIGH

VOLTAGE

COMPONENTS

OVEN

LAMP

MAGNETRON

COM.

MONITOR

SWITCH

N.C.

PRIMARY INTERLOCK SWITCH

SECOND INTERLOCK RELAY

TURNTABLE MOTOR

POWER TRANSFORMER

COM.

WHT

RED

ORG

GRY

ORG

WHT

RED

BRN

ORG

THERMAL

CUT-OUT

(OVEN)

MAGNETRON

TEMP

FUSE

FAN

MOTOR

RED

WHT

RED

POWER

UPPLY

CORD

120V

60Hz

NOTE: The

neutral

(WHT)

wire

must

connected

the

terminal

with

"N"

ark

the

power

supply

cord.

RED

WHT

NOTE: The

grounding

conductor

the

power

supply

cord

has

been

grounded

power

supply

cord

fixing

screw.

The

screw

must

always

kept

tight.

COM.

N.O.

DOOR SENSING SWITCH

GRY

GRN

Chassis

support

GRN

GRY

GRN

CN-B

BRN

WHT

ORG

RED

WHT

ORG

GRY

WHT

GRY

WHT

GRY

RY1

CN-B

SP1

CN-G

RY2

CONTROL

UNIT

WHT

RED

WHT

BLK

SENSOR

RED WHT

1 2 3

CN-F

NOTE:

Connect

the

RED

wire

lead

the

oven

side

terminal

the

power

transformer

avoid

peration

error

sensor.

Summary of Contents for R-420LK

Page 1: ...12 CIRCUIT DIAGRAMS Parts List S6603R420LPW SERVICE MANUAL R 420LW CONTENTS SHARP CORPORATION This document has been published to be used for after sales service only The contents are subject to change without notice R 420LK R 420LW MODELS In the interest of user safety the oven should be restored to its origi nal condition and only parts identical to those specified should be used WARNING TO SERV...

Page 2: ... 3 10 Procedure I NOISE FILTER TEST 8 4 11 Procedure J TOUCH CONTROL PANEL ASSEMBLY TEST 8 4 12 Procedure K KEY UNIT TEST 8 5 13 Procedure L RELAY TEST 8 5 14 Procedure M DEFROST TEST 8 6 15 Procedure N FOIL PATTERN ON THE PRINTED WIRING BOARD TEST 8 6 16 Procedure O AH SENSOR TEST 8 7 CHAPTER 9 TOUCH CONTROL PANEL ASSEM BLY 1 OUTLINE OF TOUCH CONTROL PANEL 9 1 2 ABSOLUTE HUMIDITY SENSOR CIR CUIT ...

Page 3: ...components in the interlock monitor door seal and microwave generation 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 a...

Page 4: ...h voltage capacitor 4 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 2 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 cap...

Page 5: ...he 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 Power Cooking M...

Page 6: ... brackets and hinges are not defective C The door packing 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 3 DANGER Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing Service personnel Do not contact the f...

Page 7: ... less Control Complement Touch Control System Clock 1 00 12 59 Timer 0 99 minutes 99 seconds Microwave Power for Variable Cooking Repetition Rate P HI Full power throughout the cooking time P 90 approx 90 of FULL Power P 80 approx 80 of FULL Power P 70 approx 70 of FULL Power P 60 approx 60 of FULL Power P 50 approx 50 of FULL Power P 40 approx 30 of FULL Power P 30 approx 40 of FULL Power P 20 ap...

Page 8: ...d have it replaced with a properly grounded three pronged wall receptacle or have a grounding adapter properly grounded and polarized If the extension cord must be used it should be a 3 wire 15 amp or higher rated cord Do not drape over a countertop or table where it can be pulled on by children or tripped over accidentally CAUTION DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING P...

Page 9: ...ry interlock switch open their contacts And contacts of the relay RY1 remains closed Then the monitor switch contacts close b When the door is closed from the open position the monitor switch contacts open first Then the contacts of the primary interlock switch and door sensing switch close And contacts of the relay RY1 open If the primary interlock switch and secondary interlock relay RY2 fail wi...

Page 10: ... down to zero At this time the door may be opened to stir turn or season food 5 When the timer reaches zero an audible signal sounds The shut off relay and cook relay are de energized and the power trans former oven lamp etc are turned off 6 Opening the door or touching the STOP CLEAR pad the time of day will reappear on the display and the oven will revert to an OFF condition 2 OVEN SCHEMATIC 1 O...

Page 11: ...ntact close to the ON condition due to their being normally closed At this time the secondary interlock relay RY2 and primary interlock switch are in the OFF condition contacts open due to their being normally open contact switches 2 As the door goes to a closed position the monitor switch contacts are first opened and then the door sensing switch and the primary interlock switch contacts close On...

Page 12: ...high temperatures are reached within the oven cavity the oven thermal cut out will open at 293 F 145 C causing the oven to shut down 7 MAGNETRON TEMPERATURE FUSE The magnetron temperature fuse located near the magnetron is designed to prevent damage to the magnetron if an over heated condi tion develops in the tube due to cooling fan failure obstructed air guide dirty or blocked air intake etc Und...

Page 13: ...the circuit with your hand or an uninsulated tool while the power supply is connected RE CK A B C D E F F G H RE RE CK J CK CK CK K L N O I POSSIBLE CASE AND DEFECTIVE PARTS SHORT IN POWER CORD SHORT OR OPENED WIRING MAGNETRON POWER TRANSFORMER H V RECTIFIER ASSEMBLY HIGH VOLTAGE CAPACITOR MAGNETRON TEMPERATURE FUSE SECONDARY INTERLOCK SYSTEM PRIMARY INTERLOCK SWITCH MONITOR SWITCH MONITOR FUSE OV...

Page 14: ...temperature making sure to stir the thermometer or thermocouple through the water until the maximum temperature is recorded 4 Subtract the cold water temperature from the hot water temperature The normal result should be 34 8 to 64 6 F 19 3 to 35 9 C rise in tempera ture If the water temperatures are accurately measured and tested for the required time period the test results will indicate if the ...

Page 15: ...g of the magnetron Check for restricted air flow to the magnetron especially the cool ing fan and air guide An open thermal cut out Oven indicates overheating of the oven exchange the thermal cut out and check inside of oven cavity and for improper setting of cooking time or operation of control unit Check for restricted air flow through the vent holes of the oven cavity especially the cooling fan...

Page 16: ...ndary interlock relay are operating properly according to the above Switch Test Procedure Dis connect the wire lead from the monitor switch COM termi nal Check the monitor switch operation by using the ohmmeter as follows When the door is open the meter should indicate a closed circuit When the monitor switch actuator is pushed by a screw driver through the lower latch hole on the front plate of t...

Page 17: ...esting 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 remain isolated from other components and oven chassis by using insulation tape 1 Key Unit NOTE 1 Re install the outer case cabinet 2 Reconnect the power supply cord after t...

Page 18: ...the door sensing switch is closed either close the door or short the door sensing switch connecter Use the Key unit matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP CLEAR pad making momentary contact If the control unit responds by clearing with a beep the key unit is faulty and must be replaced If the control unit does not respon...

Page 19: ...to the primary on the PWB this foil pattern acts as a fuse 1 Foil pattern check and repairs 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 Follow the troubleshooting guide given below for repair 5 Make a visual inspection of the varistor Check for burned damage and examine the transformer with a tester for the pr...

Page 20: ...e food is properly cooked 8 After the oven is started on sensor cooking condition if the sensor has not detected the vapor of the food ERROR will appear and the oven will shut off Water load cooking test WARNING The oven should be fully assembled before following procedure Make sure the oven has been plugged in at least two minutes before checking sensor cook operation The cabinet should be instal...

Page 21: ...nsulation tape 8 After that procedure re connect the power supply cord 9 Check the sensor cook operation proceed as follows a Close the door Touch the TIMER CLOCK pad once the POWER LEVEL pad twice and the START pad once And touch the number pads 1 once and the number pad 4 once b The control panel is in the sensor cooking operation c After approximately 25 seconds push plunger of select switch fo...

Page 22: ...hermistor is housed in the closed vessel filled with dry air while another in the open vessel Each sensor is provided with the protective cover made of metal mesh to be protected from the external airflow 2 Operational Principle of Absolute Humidity Sen sor The figure below shows the basic structure of an absolute humidity sensor A bridge circuit is formed by two thermistors and two resistors R1 a...

Page 23: ...rd After checking the performance of the touch control panel 1 Disconnect the power supply cord 2 Open the door and block it open 3 Re connect the leads to the primary of the power transformer 4 Re install the outer case cabinet 5 Re connect the power supply cord after the outer case is installed 6 Run the oven and check all functions a On some models the power supply cord between the touch contro...

Page 24: ...ey unit to the control unit being sure that the lead wires are not twisted 3 After aluminium foil is removed be careful that abnormal voltage due to static electricity etc is not applied to the input or output ter minals 4 Attach connectors electrolytic capacitors etc to PWB making sure that all connections are tight 5 Be sure to use specified components where high precision is required ...

Page 25: ...s adjusted accordingly 3 Soldering As the melting point of lead free solder Sn Ag Cu is higher and has poorer wettability flow to prevent damage to the land of the PWB extreme care should be taken not to leave the bit in contact with the PWB for an extended period of time Remove the bit as soon as a good flow is achieved The high content of tin in lead free solder will cause premature corrosion of...

Page 26: ...k the door and cavity face plate for damage dents cracks signs of arcing etc Carry out any remedial work that is necessary before operat ing the oven Do not operate the oven if any of the following conditions exist 1 Door does not close firmly 2 Door hinge support or latch hook is damaged 3 The door gasket or seal is damaged 4 The door is bent or warped 5 There are defective parts in the door inte...

Page 27: ...voltage wire of high voltage rectifier assembly from the magnetron 6 Disconnect the filament lead short one of the power transformer from the high voltage capacitor 7 Remove the 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 f...

Page 28: ...ASSEMBLY REMOVAL 5 Disconnect the ribbon cable of the membrane switch from the con trol unit 6 Remove the four 4 screws holding the control unit to the control panel frame And remove the control unit 7 Remove the display window from the control panel frame 8 Tear away the graphic sheet from the control panel frame 9 Tear away the membrane switch from the control panel frame 2 REINSTALLATION 1 Remo...

Page 29: ... 1 Install the fan blade to the fan motor shaft according to the following procedure 2 Hold the center of the bracket which supports the shaft of the fan motor on the flat table 3 Apply the screw lock tight into the hole for shaft of the fan blade 4 Install the fan blade to the shaft of fan motor by pushing the fan blade with a small light weight ball peen hammer or rubber mallet CAUTION Do not hi...

Page 30: ...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 Micro wave Measurement Procedure Figure C 3 Latch Switch Adjustments 14 DOOR REPLACEMENT 1 REMOVAL 1 Disconnect oven from power supply 2 Push the open button and open the door slightly 3 Insert a putty knife thickness of about 0 5mm into the...

Page 31: ...center of latch hole 2 Deviation of door alignment from horizontal line of cavity face plate is to be less than 1 0mm 3 Door is positioned with its face pressed toward cavity face plate 4 Check for microwave leakage around door with an approved micro wave survey meter Refer to Microwave Measurement Procedure NOTE The door on a microwave oven is designed to act as an electronic seal preventing the ...

Page 32: ... POWER SUPPLY CORD 120V 60Hz NOTE The neutral WHT wire must be connected to the terminal with N mark on the power supply cord RED WHT WHT H N NOTE The grounding conductor of the power supply cord has been grounded by power supply cord fixing screw The screw must always be kept tight COM N O DOOR SENSING SWITCH GRY GRN GRN to Chassis support GRN GRY GRN 2 1 CN B BRN WHT ORG RED WHT ORG ORG GRY WHT ...

Page 33: ...R420LW 12 2 2 Control Panel Circuit Figure S 2 Figure S 2 Control Panel Circuit d c a b ...

Page 34: ...R420LW 12 3 3 Printed Wiring Board Figure S 3 Figure S 3 Printed Wiring Board ...

Page 35: ... NO 3 PART NO 4 DESCRIPTION Parts marked may cause undue microwave exposure Parts marked are used in voltage more than 250V PartsGuide 1 OVEN PARTS 2 DOOR AND CONTROL PANEL PARTS INDEX DOOR PROTECTION SHEET SPADPA204WRE0 TOP PAD ASSEMBLY FPADBA632WRKZ PLASTIC BAG SSAKHA032WRE0 Not replaceable items PACKING CASE FPAK A567WRKZ R 420LW FPAK A568WRKZ R 420LK BOTTOM PAD ASSEMBLY FPADBA633WRKZ 6 2 TURNT...

Page 36: ... 11 6 4 1 10 4 3 4 5 4 7 6 2 6 1 2 2 7 1 1 12 4 10 7 3 7 3 4 1 1 13 7 9 7 5 7 6 7 8 7 8 4 4 7 10 1 5 4 8 7 7 1 4 1 4 4 6 7 8 4 2 1 9 1 8 2 3 2 3 2 3 2 3 7 10 7 4 4 9 7 10 7 1 4 12 1 7 7 10 7 10 7 2 7 2 1 2 1 11 7 10 4 14 7 1 1 2 1 3 1 1 1 14 4 16 7 8 ...

Page 37: ...186WRE0 AW Turntable motor Interchangeable 1 13 RTRN A746WRZZ BM Power transformer 1 13 RTRN A745WRZZ Power transformer for production use Interchangeable 1 14 FDTCTA225WRKZ AW AH sensor assembly CABINET PARTS 2 1 GCABUB012WRPZ BH Outer case cabinet R 420LW 2 1 GCABUA991WRPZ BH Outer case cabinet R 420LK 2 2 GDAI A403WRWZ BA Base plate 2 3 GLEGPA104WREZ AF Leg OVEN PARTS 4 1 PHOK A130WRFZ AK Latch...

Page 38: ...R420LW 4 2 DOOR AND CONTROL PANEL PARTS Actual wire harness may be different from illustration 6 6 6 5 6 7 6 8 5 6 5 7 5 3 5 4 3 5 3 4 3 3 3 2 5 1 5 2 5 5 5 8 3 1 3 1 1 3 1 2 3 5 ...

Page 39: ...pen button spring 3 4 DPWBFC543WRKZ BK Control unit 3 5 XEPS730P08XS0 AB Screw 3mm x 8mm DOOR PARTS 5 1 FDORFA412WRTZ BF Door panel 5 2 PSHEPA336WRP0 AF Sealer film 5 3 GWAKPB041WRFZ AW Door frame R 420LW 5 3 GWAKPB043WRFZ AW Door frame R 420LK 5 4 HPNL A870WREZ AS Door screen R 420LW 5 4 HPNL A871WREZ AS Door screen R 420LK 5 5 GCOVHA382WRF0 AM Choke cover 5 6 LSTPPA139WRF0 AE Latch head 5 7 MSPR...

Page 40: ...PCUSUA410WRP0 1 4 11 AB PCUSUA455WRP0 1 4 12 AD PDUC A610WRF0 1 4 13 AR PDUC A936WRFZ 1 4 14 AV PDUC A940WRPZ 1 4 16 AV PHOK A130WRFZ 1 4 1 AK PPACGA084WRF0 1 4 10 AE PPACGA272WREZ 1 4 15 AG PSHEPA336WRP0 2 5 2 AF PSHEPB190WREZ 2 3 1 1 AT PSHEPB191WREZ 2 3 1 1 AT Q QFS TA013WRE0 1 1 3 AG QSW KA066DRZZ 2 3 1 2 AQ QSW MA085WRE0 1 1 4 AF QSW MA147WRZZ 1 1 4 AG R RC QZA211WRE0 1 1 9 AV RC QZA331WRZZ 1...

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