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r-520lk r-520lw service manual

1. Key unit Membrane Switch front view Key Unit J RELAY TEST Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Disconnect the leads to the primary of the power transformer Ensure that these leads remain isolated from other components and oven chassis by using insulation tape After that procedure the power supply cord Remove the outer case and check voltage between the normal open terminal of the relay RY1 and the normal open terminal of the relay RY2 on the control unit with an A C voltmeter The meter 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 CONNECTED COMPONENTS Approx 12 0V D C Oven lamp Turntable motor Cooling fan motor Low lo cc Disconnect the power supply cord and then remove outer case Open the door and block it open 10 Discharge high voltage capacitor 11 Reconnect all leads removed from components during testing 12 Re install the outer case cabinet 13 Reconnect the power supply cord after the outer case is install
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3. The door is opened by pushing the open button on the con trol panel refer to the Figure D 1 When the open button is pushed the open button pushes up the switch lever and then the switch lever pushes up the latch head The latch heads are moved upward and released from latch hook Now the door will open Latch Heads Door Sensing S witch Door Monitor S witch S witch Lever Primary Interlock S witch Figure D 1 Door Open Mechanism DOOR SENSING AND PRIMARY INTERLOCK SWITCHES The primary interlock switch is mounted in the lower position of the latch hook and the door sensing switch in the second ary interlock system is mounted in the upper position of the latch hook They are activated by the latch heads on the door When the door is opened the switches interrupt the power to all high voltage components A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches The secondary interlock system consists of the door sensing switch and secondary interlock relay located on the control circuit board MONITOR SWITCH The monitor switch is activated the contacts opened by the latch head on the door while the door is closed The switch is intended to render the oven inoperative by means of blowing the monitor fuse when the contacts of the second ary interlock relay RY2 and primary interlock switch fail to open when the door is opened
4. 2 Indicator Circuit This circuit consists of 22 segments and 3 common electrodes using a Liquid Crystal Display 23 3 Power Source Circuit This circuit generates voltages necessary in the control unit from the AC line voltage In addition the synchronizing signal is available in order to compose a basic standard time in the clock circuit Symbol Voltage Application VSS 5V LSI IC1 4 Relay Circuit A circuit to drive the magnetron fan motor turntable motor and light the oven lamp Buzzer Circuit The buzzer is responsive to signals from the LSI to emit audible sounds key touch sound and completion sound 5 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 or closed 8 Back Light Circuit A circuit to drive the back light Light emitting diodes LD1 LD4 9 Night Light Circuit A circuit to drive the light emitting diode LD10 10 Absolute Humidity Sensor Circuit This circuit detects moisture of the cooking food to allow its automatic cooking R 520LK R 520LW R 520LK R 520LW DESCRIPTION OF LSI LSI The I O signal of the LSI is detailed the following table Power source voltage input terminal Standard voltage for LCD Terminal to change
5. Functions 1 When the door is opened the monitor switch contact 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 Asthe 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 opening the door each of these switches operate inversely 11 3 If the door is opened and the secondary interlock relay RY2 and primary interlock switch contacts fail to open the monitor fuse blows simultaneously with closing of the monitor switch contacts CAUTION BEFORE REPLACING A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH SECONDARY INTERLOCK RELAY RY2 RE LAY RY1 PRIMARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION REFER TO CHAPTER TEST PROCEDURE 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 during cooking The turntable may turn in either direction COOLING FAN MOTOR The cooling fan motor drives a blade which draws external air This cool air is directed through the air vanes sur rounding the magnetron and cools the magnetron This air is chan
6. Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings The sensor will detect the vapor given of by the spray and turn off before food is properly cooked 8 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 installed and screws tightened 1 Fill approximately 200 milliliters 7 2 oz of tap water in a 1000 milliliter measuring cup 2 Place the container on the center of tray in the oven cavity 3 Open the door 4 Touch the TIMER CLOCK once and the POWER LEVEL pad twice Close the door and touch the START pad once Open the door and touch the number pads 1 once and the number pad 4 once Close the door and touch the START pad Now the oven is in the sensor cooking condition and AH20 SENSOR and will appear in the display b The oven will operate for the first 16 seconds without generating microwave energy NOTE ERROR will appear if the door is opened or STOP CLEAR pad is touched during first stage of sensor cooking 6 After approximately 16 seconds microwave energy is produced If ERROR is displayed or the oven does not turn off replace the AH sensor or check the control unit refer to explanation below If
7. Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW cm and that the primary interlock switch secondary interlock relay does turn the oven OFF before any door movement R 520LK R 520LW SERVICE MANUAL SHARP MICROWAVE OVENS PRODUCT DESCRIPTION R 520LK R 520LW FOREWORD GENERAL INFORMATION This Manual has been prepared to provide Sharp Electronics Corp Service Personnel with Operation and Service Information for the SHARP MICROWAVE OVENS R 520LK and R 520LW OPERATION It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory customer service TROUBLESHOOTING GUIDE AND TEST PROCEDURE Check the interlock switches and the door seal carefully Special atten tion should be given to avoid electrical shock and microwave radiation hazard TOUCH CONTROL PANEL WARNING 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 no other visible damage with the oven COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE Servicing and repair work must be carried out only by trained service WIRING DIAGRAM personnel DANGER Certain initial parts are intentionally not grounded and present a risk of electrical shoc
8. Signal similar to When either Ine on key matrix is touched a corresponding signal will be Input Into P45 22 23 P44 P43 Terminal not used INTO Signal synchronized with commercial power source frequency Z This is the basic timing for time processing of LSI N O1 24 R 520LK R 520LW Signal similar to AN3 When either G11 line on key matrix is touched a corresponding signal will be input into P41 Connected to GND through the pull down resistor Auto clear terminal Signal is input to reset the LSI to the initial state when power is applied Signal similar to AN3 When either G10 line on key matrix is touched a corresponding signal will be input into P71 Signal similar to When either G9 line on key matrix is touched a corresponding signal will be input into P70 Internal clock oscillation frequency control input setting The internal clock frequency is set by inserting the ceramic filter oscillation circuit with dz respect to XOUT terminal XOUT OUT Internal clock oscillation output Output to control oscillation input to XIN Power source voltage 5 0V The power source voltage to the drive LSI is input to VSS terminal OUT Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G8 line keys on key matrix is touch
9. 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 with the contacts closed when the door is opened the closing of the monitor switch contacts will form a short circuit through the monitor fuse primary interlock switch relay RY1 and secondary interlock relay RY2 causing the monitor fuse to blow POWER LEVEL P 0 TO P 90 COOKING When Variable Cooking Power is programmed the 120 volts A C is supplied to the power transformer intermittently through the contacts of relay RY 2 which is operated by the control unit within a 32 second time base Microwave power operation is as follows VARI MODE N TIME FF TIME Power 10 32 sec 0 sec 1009 wer Power 9 P 90 30 sec 2 sec rox 909 wer Power 8 P 80 26 Sec 6 Sec Power 7 P 70 24 sec 8 SEC rox 70 wer Power 6 P 60 22 10 sec rox 60 wer Power 5 P 50 18 sec 14 sec Power 4 P 40 16 sec 16 Sec rox 409 wer Power 3 P 30 12 sec 20 sec rox 309 wer Power 2 P 20 8 SEC 24 sec Power 1 P 10 6 26 sec rox 109 wer Power 0 0 sec 32 wer Note ON OFF time ratio does not correspond with the percentage of microwave power because approx 2 seconds are needed for heating of the magnetron filament SENSOR COOKING CONDITION Using the SENSOR function
10. cooking input according to the Model By using the A D converter contained in the LSI DC voltage in accordance with the Model in operation is applied to set up its cooking constant 1 2 VL2 VL1 Signal coming from touch key When either G13 line on key matrix is touched a corresponding signal out of P20 P27 will be input into AN3 When no key is touched the signal is held at level To input signal which communicates the door open close information to LSI Door close level signal OV Door Open L level 5V Terminal not used Terminal not used 11 13 P57 P55 OUT Terminal not used CNTRO OUT Signal to sound buzzer 2 0 kHz A key touch sound OUT B Completion sound OUT Oven lamp fan motor and turntable motor driving signal To turn on and off shut off relay RY1 The 16 7 msec square waveform voltage is delivered to the RY1 driving circuit and RY2 control circuit OUT OUT Magnetron high voltage circuit driving signal To turn on and off the cook relay RY2 The Maximum signals holds during microwave cook 9 tput ing and level while not cooking In other cooking modes variable cooking the signal o of maximum 24 sec turns to level L level in repetition output an 8 sec h level Signal similar to AN3 When either G13 line on key matrix is touched a corresponding signal will be input into P46 Terminal not used
11. food is cooked without figur ing time power level or quantity When the oven senses enough steam from the food it relays the information to its microprocessor which will calculate the remaining cooking time and power level needed for best results When the food is cooked water vapor is developed the sensor senses the vapor and its resistance increase gradually When the resistance reaches the value set according to the menu supplementary cooking is started The time of supplementary cooking is determined by experi ment with each food category and inputted into the LSI An example of how sensor works Potatoes 1 Potatoes at room temperature Vapor is emitted very slowly 2 Heat Potatoes Moisture and humidity is emitted very rapidly You can smell the aroma as it cooks AH SENSOR MICRoy 3 Sensor detects moisture and humidity and calculates cooking time and variable power Cooking Sequence 1 Touch one of the SENSOR pads NOTE The oven should not be operated on sensor immediately after plugging in the unit Wait two minutes before cooking on SENSOR 2 Thecoilofshut off relay RY 1 is energized the turntable motor are turned on but the power transformer is not turned on 3 After about 16 seconds the cook relay RY 2 is energized The power transformer is turned on microwave energy is produced andfirst stage is started The 16 seconds 15 the cooling time required to remove any vapor fr
12. it open 3 Discharge high voltage capacitor 4 Disconnect the sensor connector that is mounted to control panel 5 Then connect the dummy resistor circuit see fig to the sensor connector of control panel 6 Disconnect the leads to the primary of the power transformer 7 Ensure that these leads remain isolated from other components and oven chassis by using insulation tape 8 After that procedure re connect the power supply cord 9 Check the sensor cook operation proceed as follows 9 1 Open the door Touch the TIMER CLOCK pad once and the POWER LEVEL pad twice Close the door and touch the START pad once Open the door and touch the number pads 1 once and the number pad 4 Close the door and the touch the START pad 9 2 The control panel is in the sensor cooking operation 9 3 After approximately 25 seconds 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 X X X X which is the time for detecting moisture 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 remove outer case 11 Open the door and block it open 12 Discharge high voltage capacitor 13 Disconnect the dummy resistor circuit from the sensor connector of control panel 14 Carry out necessary repair 15 Reconn
13. the door and block it open 0 Discharge high voltage capacitor 1 Reconnect all leads removed from components during testing 2 Re install the outer case cabinet 3 Reconnect the power supply cord after the outer case is installed 4 Run the oven and check all functions 5 The oven will operate for the first 16 seconds without generating microwave energy 1 1 1 1 1 20 R 520LK R 520LW AH SENSOR TEST Checking the initial sensor cooking condition WARNING The oven should be fully assembled before following procedure 1 The oven should be plugged in at least two minutes before sensor cooking 2 Room temperature should not exceed 95 gt 35720 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 of the operation manual 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 these vents There should be some space for air circulation 5 Be sure the exterior of the cooking container and the interior of the oven are dry Wipe off any moisture with a dry cloth or paper towel 6 The Sensor works with food at normal storage temperature For example chicken pieces would be at refrigerator temperature and canned soup at room temperature 7
14. the following removal procedures OUTER CASE REMOVAL To remove the outer case proceed as follows 4 Remove the remaining two 2 screws from rear 1 Disconnect the power supply cord 5 Slide the entire outer case back out about 1 inch 3 cm 2 Open the oven door and block it open to free it from retaining clips on the cavity face plate 3 Remove the two 2 screws from the lower portion of 6 Lift entire outer case from the unit the rear cabinet using a T20H Torx type or GTXH20 100 Screw driver 29 R 520LK R 520LW CAUTION 1 DISCONNECT OVEN FROM POWER SUP PLY BEFORE REMOVING OUTER CASE 2 DISCHARGE THE HIGH VOLTAGE CA PACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING NOTE When replacing the outer case the 2 special Torx screws must reinstalled the same locations 7 2 2 GTXH20 100 POWER TRANSFORMER REMOVAL Re install Disconnectthe power supply cord and then remove outer Case Open the oven door and block it open Discharge high voltage capacitor Disconnect wire leads primary and high voltage from power transformer and the filament leads from the magnetron and capacitor terminals Remove two 2 screws holding transformer to bottom plate Remove transformer from bottom plate 1 2 3 Rest transformer on the bottom plate with its primary terminals toward the
15. the oven stops after 5 minutes and ERROR is displayed the AH sensor is normal Check other parts except the AH sensor TESTING METHOD FOR AH SENSOR AND OR CONTROL UNIT To determine if the sensor is defective the simplest method is to replace it with a new replacement Sensor 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open Discharge high voltage capacitor Remove the AH sensor Install the new AH sensor Heconnect all leads removed from components during testing He install the outer case cabinet Heconnect the power supply cord after the outer case is installed Heconnect the oven to the power supply and check the sensor cook operation as follows 9 1 Fill approximately 200 milliliters 7 2 oz of tap water in 1000 milliliter measuring cup 9 2 Place the container on the center of tray in the oven cavity 9 3 Open the door 9 4 Touch the TIMER CLOCK pad once and the POWER LEVEL pad twice Close the door and touch the START pad once Open the door and touch the number pads 1 once and the number pad 4 Close the door and the touch the START pad 9 5 The control panel is in automatic Sensor operation 99 21 R 520LK R 520LW If new sensor dose not operate properly the problem is with the control unit and refer to explanation below CHECKING CONTROL UNIT 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block
16. vessel TOHTO 2 Operational Principle of Absolute Humidity Sensor The figure below shows the basic structure of an absolute humidity sensor A bridge circuit is formed by two thermistors and two resistors R1 and R2 The output of the bridge circuit is to be amplified by the operational amplifier Each thermistor is supplied with a currentto keepit heated atabout 150 2 02 the resultant heatis dissipated inthe airandifthe twothermistors are placed in different humidity conditions they show different degrees of heat conductivity leading to a potential difference between them causing an output voltage from the bridge circuit the intensity of which is increased as the absolute humidity of the air increases Since the output is very minute it is amplified by the operational amplifier Absolute humidity vs output voltage characteristic Operational H1 amplifier Output voltage Output voltage S Thermistor open vessel Thermistor closed vessel Absolute humidity g m2 Detector Circuit of Absolute Humidity Sensor Circuit This detector circuit is used to detect the output voltage of the absolute humidity circuit to allow the LSI to control sensor cooking of the unit When the unit is set in the sensor cooking mode 16 seconds clearing cycle occurs than the detector circuit starts to function and the LSI observes the initial voltage available at its AN1 terminal With this volt
17. 4 N C2 C2 SEG25 SEG22 25 R 520LK R 520LW COM3 OUT Terminal not used 78 79 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 SEGO SEG11 61 SEG SEG2 SEG3 SEG4 SEG5 SEG6 SEG7 SEG8 SEG9 vc Power source voltage GND OV A D converter power source voltage GND OV The power source voltage to drive the A D converter Connected to GND 7 2 OUT data signal Connected to LCD signal COM1 OUT Common data signal Connected to LCD signal COM2 COMO O Common data signal Connected to LCD signal VL3 Power source voltage input terminal Standard voltage for LCD Connected to GND IN IN AVSS IN A D converter power source voltage 5 0V The power source voltage to drive the A D converter UT N 26 R 520LK R 520LW 1 ventilation opening for sensing 2 3 ABSOLUTE HUMIDITY SENSOR CIRCUIT Structure of Absolute Humidity Sensor The absolute humidity sensor includes two thermistors as shown in the illustration One thermistor 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 Thermistors Sensing part Closed vessel Sensing part Open
18. 91 0O 01uF VC 5V 15V 15V R 520LK R 520LW TOUCH CONTROL PANEL SERVICING 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 terminals For this reason it is easily influenced by the surrounding high voltage power source static electricity charge in clothes etc and sometimes it is not fully protected by the built in protection circuit In order to protect CMOS LSI When storing and transporting thoroughly wrap them in aluminium foil Also wrap all PW boards containing them in aluminium foil When soldering ground the technician as shown in the figure and use grounded soldering iron and work approx 1M ohm table Servicing of Touch Control Panel We describe the procedures to permit servicing of the touch control panel of the microwave oven and the precautions you must take when doing so To perform the servicing power to the touch control panel is available either from the power line of the oven itself or from an external power source 1 Servicing the touch control panel with power supply of the oven CAUTION THE HIGH VOLTAGE TRANSFORMER OF THE MICROWAVE OVEN 15 STILL LIVE DURING SERVICING AND PRESENTS A HAZARD Therefore before checking the performance of the touc
19. 9WREO TCAUABO50MRRO TCAUABO53MRRO TINSEB44 9MRKO QW QZBO016MREO LX BZA041WREO LX CZ0052WREO XHTS740P12RVO XOTS740P12000 XCBS 30P05000 5 74 LX CZA07OWREO XOTS840P12000 To have your order filled promptly and correctly please furnish the following information lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt Main wire harnes Turntable support Turntable tray Monitor caution label DHHS Screw caution label Operation manual High voltage wire Special screw Special screw Screw 4mm x 12mm Screw 4mm x 12mm Screw 3mm x 8mm Screw 4mm x 8mm Special screw Torx tamper proof screw Screw HOW TO ORDER REPLACEMENT PARTS 1 MODEL NUMBER 2 REF NO 3 PART NO 4 DESCRIPTION Order Parts from the authorized SHARP parts Distributor for your area Defective parts requiring return should be returned as indicated in the Service Policy 40 AN Co R 520LK R 520LW No ENEMY 5 R 520LK R 520LW N 4 j 2 CONTROL PANEL PARTS 22 Fil r eas gt gt D gt fi rll 9 9 9 DOOR PARTS MISCELLANEOUS R 520LK R 520LW PACKING A
20. E EXPOSURE TO EXCESSIVE MICROWAVE ENERGY Do not operate or allow the oven to be operated with the door open Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source and make repairs as necessary 1 interlock operation 2 proper door closing 3 seal and sealing surfaces arcing wear and other damage 4 damage to or loosening of hinges and latches 5 evidence of dropping or abuse Before turning on microwave power for any service test or inspection within the microwave generating compartments check the magnetron wave guide or transmission line and cavity for proper alignment integrity and connections Any defective or misadjusted 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 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 Microwave Measurement Procedure outlined in this service manual If microwave emissions level is in excess of the specified limit contact SHARP ELECTRONICS CORPORATION immediately 1 800 237 4277 the unit operates with the door open service person should 1 tell the user
21. HEET AND MEMBRANE SWITCH REPLACEMENT Removal Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Remove the control panel assembly referring to chapter of CONTROL PANEL ASSEMBLY REMOVAL Remove the three 3 screws holding the control unit to the control panel frame And remove the control unit by releasing from tabs Remove the rubber connector from the long slit on the control panel frame Remove the night light cover release tabs from back side Remove the graphic sheet from the control panel frame See special note Remove away the membrane switch from the control panel frame See special note 0O ON O gt 31 R 520LK R 520LW Installation 1 Remove remaining adhesive on the control panel frame surfaces with a soft cloth soaked in alcohol 2 Make sure that the LCD sheet and the liquid crystal display is installed in position 3 Remove the backing paper from the new membrane switch and ribbon cable 4 Insert the ribbon cable of the membrane switch into the slit of the control panel frame 5 Adjust the upper edge and right edge of the membrane switch to the small depression on the surface of the control panel frame 6 Attach the membrane switch to the control panel frame by rubbing with a soft cloth not to scratch 7 Remove the backing paper from the new graphic sheet 8 Adjust the upper edge and right
22. ND ACCESSORIES PAD ASSEMBLY DOOR PROTECTION SHEET 6 3 TURNTABLE TRAY n x PLASTIC BAG ON TOP OF THE OVEN TRAY HOLDER 6 6 OPERATION MANUAL 7 AE BOTTOM PAD ASSEMBLY 6 2 TURNTABLE SUPPORT PACKING CASE Non replaceable items 43 R 520LK R 520LW SHARP COPYRIGHT 2006 BY SHARP CORPORATION ALL RIGHTS RESERVED No part of this publication may be reproduced stored in retrieval systems or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without prior written permission of the publisher 2006 SHARP CORP 5M2 00E Printed in U S A
23. OTES SWITCH 1 CIRCUITS SUBJECT TO CHANGE WITHOUT NOTICE 2 TERMINAL WITH PROJECTION OR OPPOSITE BLUE MARK ON LAMP SOCKET MUST BE CONNECTED TO NEUTRAL WIRE 3 ONLY CERTAIN MODELS USE THE ABSOLUTE HUMIDITY SENSOR 4 POWER TRANSFORMER TOP FINISH LEAD TERMINAL MUST BE CONNECTED TO THE NEUTRAL WHT WIRE Figure O 1 Oven Schematic Off Condition SCHEMATIC NOTE CONDITION OF OVEN 1 DOOR CLOSED 2 COOKING TIME PROGRAMMED 3 VARIABLE COOKING CONTROL HIGH 4 START PAD TOUCHED CAVITY MAGNETRON TEMPERATURE TEMPERATURE ORG FUSE RED FUSE ORG DOOR SENSING SWITCH BLK POWER TRANSFORMER HUMIDITY SENSOR pesa Sa SOURCE RY2 SECONDARY INTERLOCK MONITOR FUSE 20A CONTROL UNIT Z 60Hz CAPACITOR xx uF MONITOR SWITCH WHT tt VOLTAGE zz RECTIFIER NOISE FILTER TO SOURCE TO LOAD GRY WHT WHT PRIMARY WHT INTERLOCK NOTES SWITCH 1 CIRCUITS SUBJECT TO CHANGE WITHOUT NOTICE 2 TERMINAL WITH PROJECTION OR OPPOSITE BLUE MARK ON LAMP SOCKET MUST BE CONNECTED TO NEUTRAL WIRE 3 ONLY CERTAIN MODELS USE THE ABSOLUTE HUMIDITY SENSOR 4 POWER TRANSFORMER TOP FINISH LEAD TERMINAL MUST BE CONNECTED TO THE NEUTRAL WHT WIRE Figure O 2 Oven Schematic Cooking Condition 10 RELAY rte MAGNETRON R 520LK R 520LW DESCRIPTION AND FUNCTION OF COMPONENTS DOOR OPEN MECHANISM
24. OUND FISH MEAT SEAFOOD FROZEN CHICKEN FROZEN ENTREES BREAST VEGETABLES REHEAT FRESH ROLLS FROZEN ROLLS Muffins BEVERAGE MUFFINS DEFROST GROUND STEAKS BONELESS MEAT CHOPS POULTRY POULTRY R 520LK R 520LW OPERATION DESCRIPTION OF OPERATING SEQUENCE The following is a description of component functions dur ing oven operation OFF CONDITION Closing the door activates the door sensing switch and pri mary interlock switch In this condition the monitor switch contacts are opened When oven is plugged in 120 volts A C is supplied to the control unit Figure O 1 1 The display will show flashing 88 88 To set any program or set the clock you must first touch the STOP CLEAR pad The display will clear and will appear COOKING CONDITION Program desired cooking time by touching the NUMBER pads Program the power level by touching the POWER LEVEL pad and then a Number pad When the START pad is touched the following operations occur 1 The contacts of relays are closed and components connected to the relays are turned on as follows For details refer to Figure O 2 RELAY NNECTED COMPONENT HY ovenlamp turntable motor fan motor _ _RY 2 powertransfomer 2 120 volts A C is supplied to the primary winding of the power transformer and is converted to about 3 3 volts A C output on the filament winding and approximately 2370 volts A C on the high volta
25. R 520LK R 520LW SHARP SERVICE MANUAL S46M260R520LE MICROWAVE OVEN R 520LK R 520LW MODELS R 520LW In the interest of user safety the oven should be restored to its original condition and only parts identical to those specified should be used WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of producing very high voltage and current contact with following parts may result in a severe possibly fatal electrical shock High Voltage Capacitor High Voltage Power Transformer Magnetron High Voltage Rectifier Assembly High Voltage Harness etc TABLE OF CONTENTS Page PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY INSIDE FRONT COVER BEFORE SERVICING INSIDE FRONT COVER WARNING TO SERVICE PERSONNEL MICROWAVE MEASUREMENT PROCEDURE FOREWORD AND WARNING PRODUCT SPECIFICATIONS GENERAL INFORMATION OPERATION TROUBLESHOOTING GUIDE TEST PROCEDURE TOUCH CONTROL PANEL COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE PICTORIAL DIAGRAM CONTROL UNIT CIRCUIT PRINTED WIRING BOARD PARTS LIST PACKING AND ACCESSORIES SHARP ELECTRONCS CORPORATION document has been published to be used for after sales service only The contents are subject to change without notice Service Headquarters Sharp Plaza Mahwah New Jersey 07430 2135 R 520LK R 520LW PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBL
26. There is visible damage to the oven Carry out any remedial work that is necessary before Do not operate the oven operating the oven 1 Without the RF gasket Magnetron Do not operate the oven if any of the following conditions 2 f the wave guide or oven cavity are not intact exist 3 If the door is not closed 4 the outer case cabinet is not fitted WARNING FOR WIRING To prevent an electric shock take the following pre 3 Sharp edge cautions Bottom plate Oven cavity Waveguide flange 1 Before wiring Chassis support and other metallic plate 1 Disconnect the power supply cord 4 Movable parts to prevent a fault 2 Open the door block it open Fan blade Fan motor Switch Switch lever Open 3 Wait 60 seconds then discharge the high voltage button capacitor Do not catch the wire leads in the outer case cabinet 2 Don t let the wire leads touch to the following parts Insert the positive lock connector until its pin is locked 1 High voltage parts and make sure that the wire leads do not come off Magnetron High voltage transformer High voltage even if the wire leads are pulled capacitor and High voltage rectifier assembly To prevent an error function connect the wire leads 2 Hot parts correctly referring to the Pictorial Diagram Oven lamp Magnetron High voltage transformer and Oven cavity Please refer to OVEN PARTS CABINET PARTS CONTROL PANEL PARTS DOOR PARTS when carrying out any of
27. age 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 R98 R102 Changing the resistance values results in that there is the same potential at both F 3 terminal of the absolute humidity sensor and ANO 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 Sensor Cooking mode As the sensor cooking proceeds 27 the food is heated to generate moisture by which the resistance balance of the bridge circuit is deviated to increase the voltage available at AN1 terminal of the LSI Then the LSI observes that voltage at AN1 terminal and compares it with its initial value and when the comparison rate reaches the preset value fixed for each menu to be cooked the LSI causes the unit to stop sensor cooking thereafter the unit goes in the next operation automatically When the LSI starts to detect the initial voltage at AN1 terminal 16 seconds after the unit has been put in the Sensor Cooking mode if it is not possible to balance the bridge circuit due to disconnection of the absolute humidity sensor ERROR will appear on the display and the cooking is stopped ________ 11 99 300k 12 R100 150k 13 3 l 10 897 47k e Thermistor in closed vessel S Thermistor in open vessel C
28. arked A may cause undue microwave exposure The parts marked are used in voltage more than 250V 5 MARK PARTS DELIVERY SECTION R 520LK R 520LW l l l l A F2 0 N p CO CO ho ho S 7 018 0 FH DZB013MRY0 RLMPTA087WRZZ RMOTEA433WRZZ FFS BA016 KIT OSW MAO 85WREO OFS TAO14WREO RV MZA293WREO RMOTDA264 KIT RTRN B088MREO FACCDBOO3MREO QFS TAO13WREO FPWBFA380WRKZ 061 GLEGPBOOAMRFO GCABUBO96MRPO GCABUBO8 9MRPO GPNLCBO90MRKO HPNLFBO24MRFO HPNLFBO25MRFO FUNTKB461 KIT FUNTKB469 KIT JBTN B201MRFO JBTN B20 3MRFO MSPRCA045WREO XEPSD30PO08XSO QCNC A020WRZZ PSHEPBO37WREZ RLCDSA116DRZZ 6 HPNLCB179MRFO LBNDKBOO7MRPO 62 018 MLEVPBO16MRFO PDUC B125MRFOA NFANPBOO6MREO PDUC BO088MRFO PCOVPBO085MRPO PPACGBO14MRF0 PCUSUBO80MRPO LANGQBO25MRPO GWAKPB22 6MRRO GWAKPB228MRRO LSTPPBO2IMRFO MSPRTAO46WREO FDORFBO75MRTO lt lt lt lt lt lt lt lt lt lt lt lt S lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt 5 ELECTRIC PART High voltage capacitor High voltage rectifier assembly Oven lamp socket motor Monitor switch V 16G 2C25 and fuse assembly Primary interl
29. ces enter the gap between or rubber mallet the rotor and the stator of the fan motor because the CAUTION rotor is easily shaven by pliers and metal pieces may Do not hit the fan blade strongly when installed be produced because the bracket be disfigured not touch the pliers to the coil of the fan motor Make sure that the fan blade rotates smooth after because the coil may be cut or injured installation Do not disfigure the bracket by touching with the sure that the axis of the shaft is not slanted pliers 5 Install the fan motor to the oven cavity back plate with 8 Remove the fan blade from the shaft of the fan motor by the two 2 screws pulling and rotating the fan blade with your hand 6 Connect the wire leads to the fan motor referring to the 9 Now the fan blade and the fan motor will be free pictorial diagram Table Center of These the positions bracket Axis that should be pinched 4 with pliers Rear View Side View DOOR SENSING SWITCH PRIMARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL Disconnect the power supply cord and remove outer 8 Switch is now free 2 Open the door and block it open At this time switch lever will be free do not lose it 3 Discharge high voltage capacitor Re install 4 Disconnect wire leads from the switches 1 Re install each switch in its place The primary interlock 5 Remove two 2 screws hold
30. cook cycle but ex tremely uneven heating is produced in oven load food Oven does not cook properly when programmed for Cooking Power P 50 mode Operates properly on Cooking HiGiH 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 2 2 gt pepe LOW VOLTAGE arti L KEY UNIT 1 10 OJD TOUCH CONTROL PANEL SSE eH COMPU DEFROST gt gt lt O 2 gt gt lt N 2 lt 2 gt TEST PROCEDURES PROCEDURE LETTER A COMPONENT TEST MAGNETRON ASSEMBLY 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 13 R 520LK R 520LW TEST PROCEDURES PROCEDURE COMPONENT TEST 4 To test for an open filament isolate the magnetron from the high voltage circuit A continuity check across the magnetron filament leads should indicate less than 1 ohm 5 To test fora shorted magnetron connect the ohmmeter leads between the magnetron filament leads and chassis ground This test should indicate an infinite resistance If there is little or no resistance the magnetron is grounded and must be replaced Reconnect all leads removed from components during testing Rein
31. cover by inserting a putty knife as shown Figure C 4 Release choke cover from door panel Now choke cover is free Release two 2 pins of door panel from two 2 holes of upper and lower oven hinges by lifting up Now door panel with door frame is free from oven 34 Figure C 4 Door Disassembly 9 Release the door panel from twelve 12 tabs of door frame 10 Remove the door panel from the door frame 11 Now door panel with sealer film is free 12 Tear sealer film from door panel 13 Now door panel is free 14 Slide latch head upward and remove it from door frame with releasing latch spring from door frame and latch head 15 Now latch head and latch spring are free 16 Remove door screen from door frame 17 Now door frame is free RE INSTALL 1 Re install door screen to door frame 2 Re install the latch spring to the latch head Re install the latch spring to the door frame Re install latch head to door frame 3 Re install door panel to door frame by fitting twelve 12 tabs of door frame to twelve 12 holes of door panel 4 Putsealer film on door panel Refer to Sealer Film about how to handle new one 5 Catch two 2 pins of door panel on two 2 hole of upper and lower oven hinges 6 Re install choke cover to door panel by pushing Note After any service to the door A Make sure that door sensing switch and primary interlock switch are operating properly Refer to chapter Test Pr
32. ctivates an operational state that is equivalent to the oven door being closed As for the sensor related controls of the touch control panel checking them is possible if dummy resistor s with resistance equal to that of the controls are used 2 Servicing the touch control panel with power supply from an external power source Disconnect the touch control panel completely from the oven proper and short both ends of the door sensing switch on PWB of the touch control panel which activates an operational state that is equivalent to the oven door being closed Connect an external power source to the power input terminal of the touch control panel then itis 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 Servicing Tools Tools required to service the touch control panel assembly 1 Soldering iron 30W It is recommended to use a soldering iron with a grounding terminal 2 Oscilloscope Single beam frequency range DC 10MHz type or more advanced model 3 Others Hand tools 4 Other Precautions 1 Before turning on the power source of the control unit remove the aluminium foil applied for preventing static electricity 2 Connect the connectors of the key unit to the control unit being sure that the lead wires are not twisted 3 After aluminium foil is removed be carefu
33. d examine the transformer with a tester for the presence of layer short circuit check the primary coil resistance which is approximately 563y 10 If any abnormal condition is detected replace the control unit assembly 6 Reconnect all leads removed from components during testing 7 Re install the outer case cabinet 8 Reconnect the power supply cord after the outer case is installed 9 Run the oven and check all functions 2 Follow the troubleshooting guide given below if indicator does not light up after above check and repairs are finished 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open Discharge high voltage capacitor Disconnect the leads to the primary of the power transformer Ensure that these leads remain isolated from other components and oven chassis by using insulation tape 6 After that procedure re connect the power supply cord 7 Follow the troubleshooting guide given below for repair STEPS OCCURRENCE CAUSE OR CORRECTION The rated AC voltage is not present between the normal open terminal of the relay RY1 and Check supply voltage and oven power cord the normal open terminal of the relay RY2 1 2 The rated AC voltage is present at primary side Low voltage transformer or secondary circuit defective of low voltage transformer Check and replace control unit assembly Disconnect the power supply cord and then remove outer case 8 9 Open
34. ding adapter properly grounded and polar ized 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 RE MOVE THE ROUND GROUNDING PRONG FROM THIS PLUG 1 One touch door open button R 520LK R 520LW Grounded Receptacle Box 3 Pronged Plug Grounding Pin 3 Pronged Receptacle Push to open door OVEN DIAGRAM 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 Oven door with see through window Ventilation openings Rear Auto Touch control panel 10 Wave guide cover Time display Digital display 99 minutes 11 Power supply cord 99 seconds TOUCH CONTROL PANEL NOTE The directed features are disabled after one minute when the oven is not in use These features are automatically enabled when the door is opened and closed or the STOP CLEAR pad is pressed 2 7 4 9 1 3 5 6 8 0 POWER CUSTOM HELP LEVEL TIMER STOP TART CLOCK CLEAR MINUTE PLUS HOT SENSOR KEEP WARM WATER REHEAT PLUS SENSOR COOK FRESH POPCORN VEGETABLES GR
35. e disconnected It may in some cases be necessary to connect the power supply 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 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 Don t Touch Danger High Voltage When the testing is completed 1 Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Reconnect the leads to the primary of the power transformer 5 Reinstall the outer case cabinet 6 Reconnect the power supply cord after the outer case is installed 7 Run the oven and check all functions After repairing 1 Reconnect all leads removed from components during testing 2 Reinstall the outer case cabinet 3 Reconnect the power supply cord after the outer case is installed 4 Run the oven and check all functions Microwave ovens should not be operated empty To test for the presence of microwave energy within a cavity place a cup of cold water on the oven turntable close the door and set the power to HIGH and set the microwave timer for two 2 minutes When the two minut
36. e magnetron duct by turning the socket counterclockwise 7 Remove the oven lamp from the socket by turning the oven lamp 8 Now the oven lamp and the oven lamp socket are POSITIVE LOCK CONNECTOR NO CASE TYPE REMOVAL 1 Disconnect the power supply cord and then remove outer case Open the door and block it open lt Discharge high voltage capacitor Push the lever of positive lock connector Pull down on the positive lock connector Terminal ore CAUTION WHEN CONNECTING THE POSITIVE LOCK CONNECTORS TO THE TERMINALS CON NECT THE POSITIVE LOCK SO THAT THE LEVER FACES YOU 2 cb Pull down Figure C 2 Positive lock connector CONTROL PANEL ASSEMBLY REMOVAL Disconnectthe power supply cordandthen remove outer NOTE 1 Before attaching a new key unit wipe off remaining case adhesive on the control panel frame surfaces 2 Open the door and block it open completely with a soft cloth soaked in alcohol 3 Discharge high voltage capacitor 2 When attaching the key unit to the control panel 4 Disconnect the wire leads from panel components a a i 5 Remove the one 1 screw holding the control panel 2 Cp OOH ONE PAte Place the key unit firmly to the control panel frame 6 Slide the control panel assembly upward and remove by rubbing with soft cloth not to scratch it 7 Now individual components can be removed GRAPHIC S
37. easure the 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 33 to 62 F 18 6 to 34 5 C rise in temperature If the water temperatures are accurately measured and tested for the required time period the test results will indicate if the magnetron tube has low power output low rise in water temperature which would extend cooking time or high power output high rise in water temperature which would reduce cooking time Because cooking time can be adjusted to compensate for power output the magnetron tube assembly should be replaced only if the water temperature rise test indicates a power output well beyond the normal limits The test is only accurate if the power supply line voltage is 120 volts and the oven cavity is clean POWER TRANSFORMER TEST Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Disconnect the primary input terminals and measure the resistance of the transformer with an ohmmeter Check for continuity of the coils with an ohmmeter On the x 1 scale the resistance of the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be approximately 90 ohms the resistance of the filament coil should be less than 1 ohm Reconnect all lead
38. ect all leads removed from components during testing and repairing 16 Re install the outer case cabinet 17 Reconnect the power supply cord after the outer case is installed Run the oven and check all functions 18 Carry out Water load cooking test again and ensure that the oven works properly R1 R2 220 1 1 2W 4 30 5 1 4W 4 1 5 1 4W Plunger NC NO To connector F on Control Unit gt 1 lt F2 c H CONNECTOR Sensor Dummy Resistor Circuit 22 TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units 1 Key Unit 2 Control Unit The Control Unit consists of Power Unit and LSI Unit The principal functions of these units and the signals com municated among them are explained below Key Unit The key unit is composed of a matrix signals generated in the LSI are sent to the key unit through P20 P27 When a key pad is touched a signal is completed through the key unit and passed back to the LSI through P70 P71 P41 P45 P47 and ANS to perform the function that was requested Control Unit Control unit consists of LSI reset circuit indicator circuit power source circuit relay circuit buzzer circuit synchroniz ing signal circuit and back light circuit 1 Reset Circuit This circuit generates a signal which resets the LSI to the initial state when power is supplied
39. ed OUT Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G7 line keys on key matrix is touched Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G6 line keys on key matrix is touched Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P45 P47 and terminal while one of G5 line keys on key matrix is touched Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G4 line keys on key matrix is touched Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G3 line keys on key matrix is touched Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and AN3 terminal while one of G2 line keys on key matrix is touched OUT Key strobe signal Signal applied to touch key section A pulse signal is input to P70 P71 P41 P45 P47 and terminal while one of G1 line keys on key matrix is touched OUT Back light signal Light emitting diodes driving signal 42 46 P16 P12 OUT Terminal not used 47 50 OUT Terminal not used 51 72 SEG21 SEGQ OUT Segment data signal
40. ed 14 Run the oven and check all functions COMPU DEFROST TEST WARNING The oven should be fully assembled before following procedure 1 Open the door 2 Place one cup of water in the center of the turntable tray in the oven cavity 3 Touch the Defrost pad once 4 Press 2 then press 5 5 Touch the START pad 6 The oven is in Defrost cooking condition 7 The oven will operate as follows 1ST STAGE 2ND STAGE 3RD STAGE STEAKS CHOPS LEVEL TIME LEVEL TIME LEVEL TIME 0 510 20sec 30 8 If improper operation is indicated the control unit is probably defective and should be checked 19 R 520LK R 520LW TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST L FOIL PATTERN ON THE PRINTED WIRING BOARD TEST To protect the electronic circuits this model is provided with a fine foil pattern added 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 STEPS OCCURRENCE CAUSE OR CORRECTION Only pattern at a is broken Insert jumper wire J1 and solder Pattern at a and b are broken Insert the RCILF2003YAZZ between and d 5 Make a visual inspection of the varistor Check for burned damage an
41. edge of the graphic sheet to the large depression on the surface of the control panel frame 9 Attach the graphic sheet to the control panel frame by rubbing with a soft cloth not to scratch 10 Attach the ribbon cable to the control panel frame rear side 11 Place the edge of the membrane switch s ribbon cable on the lower portion of the liquid crystal display 12 Insert the rubber connector into the long slit on the control panel frame 13 Reinstall the control unit to the control panel frame with the three 3 screws NOTE Do not touch the contact surface of the ribbon cable edge and the rubber connector with a finger directly not to be oxidized If display digits are missing or scrambled remove control unit and make sure that there is not any trash or foreign substance on the contact surface of the rubber connector Use an adhesive tape to clean the contact surface of the rubber connector Heat gun will soften adhesive Control panel frame LCD sheet Liquid crystal display Ribbon cable Liquid crystal of membrane 9 display p Contact surface Control panel frame Rear side Slit Long slit Membrane switch sheet Contact surface Rubber connector Graphic TURNTABLE MOTOR REMOVAL Disconnect the power supply cord r turntable and Rirntable support from oven 5 Disconnect wire leads from turntable motor cavity See Positive lock connector removal Laythe oven
42. es has elapsed timer at zero carefully check that the water is now hot If the water remains cold carry out Before Servicing procedure and re examine the connections to the component being tested When all service work is completed and the oven is fully assembled the microwave power output should be checked and a microwave leakage test should be carried out R 520LK R 520LW MICROWAVE MEASUREMENT PROCEDURE A Requirements 1 Microwave leakage limit Power density limit The power density of microwave radiation emitted by a microwave oven should not exceed 1mW cm at any point 5cm or more from the external surface of the oven measured prior to acquisition by a purchaser and thereafter through the useful life of the oven 5 mW cm at any point 5cm or more from the external surface of the oven 2 Safety interlock switches Primary interlock relay switch shall prevent microwave radiation emission in excess of the requirement as above mentioned Secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of 5 mW cme2 at any point 5cm or more from the external surface of the oven B Preparation for testing Before beginning the actual measurement of leakage proceed as follows 1 Make sure that the actual instrument is operating normally as specified in its instruction booklet Important Survey instruments that comply with the requirement for instrumentation as prescribed by the perf
43. ge winding 3 filament winding voltage heats the magnetron filament and the H V winding voltage is sent to a voltage doubler circuit 4 The microwave energy produced by the magnetron is channelled through the waveguide into the cavity feed box and then into the cavity where the food is placed to be cooked 5 Upon completion of the cooking time the power transformer oven lamp etc are turned off and the generation of microwave energy is stopped The oven will revert to the OFF condition 6 When the door is opened during a cook cycle the monitor switch door sensing switch primary interlock switch relay RY1 and secondary interlock relay are activated with the following results The circuits to the turntable 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 monitor switch electrically monitors the operation of the primary interlock switch and secondary interlock relay and is mechanically associated with the door so that it will function in the following sequence 1 When the door opens from the closed position the secondary interlock relay RY2 and primary interlock switch open their contacts And contacts of the relay RY1 remains closed Then the monitor switch contacts close 2 When the door is closed from the open position the monitor switch
44. h control panel 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 6 After that procedure re connect the power supply cord 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 control panel and the oven itself is so short that the two can t be separated For those models check and repair all the controls sensor related ones included of the touch control panel while keeping it connected to the oven B On some models the power supply cord between the touch control panel and the oven proper is long enough that they may be separated from each other For those models it is possible to check and repair the controls of the touch control panel while keeping it apart from the oven proper in this case you must short both ends of the door sensing switch on PWB of the touch control panel with a jumper which a
45. h voltage capacitor Reconnect the leads to the primary of the power transformer Reinstall the outer case cabinet OQ N 12 CONDITION OFF CONDITION COOKING CONDITION SENSOR COOKING CONDITION R 520LK R 520LW CK Check RE Replace merece fefefe fe fp Fie F r veneris pn DEFECTIVE PARTS LLI 02 5 IZ m lt 0 A m au Z O Z LL 2 lt PROBLEM Home fuse or circuit breaker blows when power cord is plugged into wall receptacle C T fuse blows when power cord is plugged into wall receptacle o SECONDARY INTERLOCK SYSTEM L Pi ptf fot O hom 2215035 HIGH VOLTAGE CAPACITOR CAVITY TEMPERATURE FUSE 1 MAGNETRON TEMP FUSE All letters and indicators do not ap pear in display when power cord is first plugged into wall outlet EGER Display does not operate properly when STOP CLEAR key is touched Buzzer should sound and or time of day should appear in displa oven amp doosnotightwnendcor O O is opened oven lamp does not go out when door is closed Imntabie motor do not operate Oven does not go into cook cycle QUCHCO Oven seems to be operating but little or no heat is produced in oven load Food incompletely cooked or not dl dll at eriad O OOK C Oven goes into a
46. he plunger of the monitor switch is pressed with the door closed Secure the screws with washers firmly Check the operation of all switches If each switch has not activated with the door closed loosen screw and adjust the latch hook position After adjustment check the following 1 In and out play of door remains less than 0 5mm when in the latched position First check upper position of latch hook pushing and pulling upper portion of door toward the oven face Then check lower portion of the latch hook pushing and pulling upper portion of door toward the oven face Both results play in the door should be less than 0 5mm The door sensing switch and primary interlock switch interrupt the circuit before the door can be opened Monitor switch contacts close when door is opened Re install outer case and check for microwave leakage around door with an approved microwave survey meter Refer to Microwave Measurement Procedure Latch Heads Door Sensing S witch Door Monitor S witch S witch Lever Primary Interlock S witch Figure C 3 Latch Switch Adjustments DOOR REPLACEMENT REMOVAL 1 2 3 D Disconnect power supply cord Push the open button and open the door slightly Insert a putty knife thickness of about 0 5mm into the gap between the choke cover and door frame as shown in Figure C 4 to free engaging parts Pry the choke
47. ing latch hook to oven flange monitor switches are in the lower position and the door 6 Remove latch hook assembly from oven flange sensing switch is in the upper position 7 Push outward on the two 2 retaining tabs holding switch 2 Re connect wire leads to each switch in place 33 R 520LK R 520LW 3 4 1 2 3 Secure latch hook with two 2 mounting screws to oven flange Make sure that the monitor switch is operating properly and check continuity of the monitor circuit Refer to chapter Test Procedure and Adjustment procedure DOOR SENSING SWITCH PRIMARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENT Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor lf the door sensing switch primary interlock switch and moni tor switch do not operate properly due to a misadjustment the following adjustment should be made 4 5 Loosen the two 2 screws holding latch hook to the oven cavity front flange With door closed adjust latch hook by moving it back and forth and up and down In and out play of the door allowed by the upper and lower position of the latch hook should be less than 0 5mm The vertical position of the latch hook should be adjusted so that the door sensing switch and primary interlock switch are activated with the door closed The horizontal position of the latch hook should be adjusted so that t
48. ive tape on the backing film of the sealer film as shown in Fig C 6 2 Tear the backing film by pulling the adhesive tape 3 Put the pasted side of the sealer film on the door panel Sealer film Backing film Adhesive tape YAWYOASNVYLL y 5 sH 1HM 1HM HOLIMS H9IH ON AMVIIHd LHM i p 4 1342008 ANY SLNANOdWOD ADVLIOA NJAO dm AHVONOO3S LHM oz YOLOW NVJ L CYR S i 4 EQ SAUA YOLOW 5181 p109 Ajddns euj uo yew y pejoeuuoo snw AYD LHM Ienn u eu 915135 dIN31 NOHIJNOVIN LHM LHM ALON 3Snd dii ALIAVO 5 M9J9S 941 i puoo Ajddns Jamod Aq 1 u q Ban sey p109 Ajddns eui 1g ooa Jo Buipunoj6 eu ALON oa YOSNAS HV R 520LK R 520LW 36 R 520LK R 520LW 5 S S inB 3 LINN A3M SA1TEVLADAA AuL1nod lV3H3H N3ZO4 SSATANOd YOSNAS 009 YOSNas IYIN 5 N3O2dOd S33HLN3 S318V1393A N3M2IH2 17577 315 HS3MHJ aooavas HSI3
49. k only during servicing Service person PARTS LIST nel Do not contact the following parts while the appliance is energized High Voltage Capacitor Power Transformer Magnetron High Voltage Rectifier Assembly High Voltage Harness If provided Vent Hood Fan assembly Cooling Fan Motor All the parts marked gt on parts list are used at voltages more than 250V Removal of the outer wrap gives access to voltage above 250V All the parts marked A on parts list may cause undue microwave exposure by themselves or when they are damaged loosened or removed SHARP ELECTRONICS CORPORATION SHARP PLAZA MAHWAH NEW JERSEY 07430 2135 R 520LK SPECIFICATION R 520LW ITEM o Power Requirements 120 Volts 14 3 Amperes 1700 watts 60 Hertz Single phase 3 wire grounded Power Output 1200 watts IEC TEST PROCEDURE Operating frequency of 2450MHz Case Dimensions Width 24 Height 13 3 8 Depth 19 1 8 Cooking Cavity Dimensions Width 17 3 8 Height 10 1 2 2 0 Cubic Feet Depth 18 5 8 Control Complement Touch Control System Clock 1 00 12 59 Timer 0 99 min 99 seconds Microwave Power for Variable Cooking Hepetition Rate Full power throughout the cooking time 90 of Full Power 80 of Full Power 7096 of Full Power 6096 of Full Power 5096 of Full Power 4096 of Full Power 30 of Full Power 2096 of Full Power 10926 of Full Power No power throughout the coo
50. king time START MINUTE PLUS pad Sensor Cook pads Defrost pads Number selection pads Power Level pad Timer Clock pad Stop Clear pad Keep Warm Plus Reheat pads Popcorn Night light Sensor reheat and Hot water Oven Cavity Light Safety Standard UL Listed FCC Authorized DHHS Rules CFR Title 21 Chapter 1 Subchapter J 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 National Electrical Code and local codes and ordinances In the event of an electrical short circuit grounding reduces the risk of electric shock by providing an escape wire for the electric current WARNING Improper use of the grounding plug can result in a risk of electric shock Electrical Requirements The electrical requirements are a 120 volt 60 Hz AC only 15 or 20 amp fused electrical supply It is recommended that a separate circuit serving only this appliance be provided When installing this ap pliance observe all applicable codes and ordinances A short power supply cord is provided to reduce risks of becoming entangled in or tripping over a longer cord Where a two pronged wall receptacle is encountered it is the personal responsibility and obligation of the customer to contact a qualified electri cian and have it replaced with a properly grounded three pronged wall receptacle or have a groun
51. l that abnormal voltage due to static electricity etc is not applied to the input or output terminals 4 Attach connectors electrolytic capacitors etc to PWB making sure that all connections are tight 28 R 520LK R 520LW COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING AGAINST HIGH VOLTAGE Microwave ovens contain circuitry capable of producing very high voltage and current Contact with the following parts may result in severe possibly fatal electric shock Example High Voltage Capacitor Power Transformer Magnetron High Voltage Rectifier Assembly High Voltage Harness etc To Avoid possible exposure to microwave energy please follow the instructions below before operating the oven Disconnect the power supply cord Door does not close firmly Make sure that a definite click can be heard when Door hinge support or latch hook is damaged the microwave oven door is unlatched Hold the door The door gasket or seal is damaged in a closed position with one hand then push the door The door is bent or warped open button with the other this causes the latch leads There are defective parts in the door interlock to rise it is then possible to hear a click as the door system switches operate 6 There are defective parts in the microwave generating Visually check the door and cavity face plate for damage and transmission assembly dents cracks signs of arcing etc 7
52. ls of the Secondary Interlock Relay Check the state of the relay contacts using a ohmmeter The relay contacts should be open If the relay contacts are closed replace the circuit board entirely or the relay itself Reconnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions Ic COON O O1 16 PROCEDURE G 1 2 3 4 5 6 7 8 R 520LK R 520LW TEST PROCEDURES COMPONENT TEST MONITOR SWITCH TEST Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Before performing this test make sure that the primary interlock switch and the secondary interlock relay are operating properly according to the above Switch Test Procedure Disconnect the wire lead from the monitor switch COM terminal 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 the oven cavity with the door opened in this condition the plunger of the monitor switch is pushed in the meter should indicate an open circuit If improper operation is indicated the switch may be defective After testing the monitor switch reconnect the
53. neled through the oven cavity to remove steam and vapors given off from the heating foods It is then exhausted through the exhausting air vents at the oven cavity CAVITY TEMPERATURE FUSE The cavity temperature fuse located on the top of the oven cavity is designed to prevent damage to the oven by fire If the food load is overcooked by either error in cook time or defect in the control unit the cavity temperature fuse will open Under normal operation the cavity temperature fuse remains closed However when abnormally high temperatures are reached within the oven cavity the cavity temperature fuse will open at 302 F 150 C causing the oven to shut down NOTE This is a fuse It does not reset MONITOR FUSE 1 The monitor fuse blows when the contacts COM NO of the primary interlock relay RY2 and secondary interlock switch remain closed with the oven door open and when the monitor switch closes 2 If the wire harness or electrical components are short circuited this monitor fuse blows to prevent an electric shock or fire hazard Magnetron TEMPERATURE FUSE The magnetron temperature fuse located near the magne tron is designed to prevent damage to the magnetron if an over heated condition develops in the tube due to cooling fan failure obstructed air guide dirty or blocked air intake etc Under normal operation the magnetron temperature fuse R 520LK R 520LW TROUBLESHOOTING GUIDE Never touch any part in
54. nnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions MAGNETRON TEMPERATURE FUSE TEST RON Disconnect power supply cord and then remove outer case the door and block it open Discharge high voltage capacitor Acontinuity check across the magnetron temperature fuse terminals should indicate a closed circuit unless the temperature of the magnetron temperature fuse reaches approximately 302 F 150 C An open magnetron temperature fuse indicates overheating of the magnetron Check for restricted air flow to the magnetron especially the cooling fan air guide Reconnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed 15 R 520LK R 520LW TEST PROCEDURES ee COMPONENT TEST 8 Run the oven and check all functions CAUTION IFTHE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOMTEMPERATURE REPLACE TEMPERATURE FUSE PRIMARY INTERLOCK SWITCH TEST Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Isolate the switch and connect the ohmmeter to the common COM and normally open NO terminal of the switch The meter should indicate an o
55. nnect the power supply cord and then remove outer case 2 Open the door and block it open Discharge high voltage capacitor Reconnect all leads removed from components during testing Re install the outer case cabinet Reconnect the power supply cord after the outer case is installed 3 4 5 6 7 Run the oven and check all functions RON ot Disconnect power supply cord then remove outer case Open the door and block it open Discharge high voltage capacitor Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit check the circuit between the pins of the key unit that correspond to the STOP CLEAR pad When the pad is pressed the ohmmeter should indicate short circuit When the pad is released the ohmmeter should indicate open circuit If incorrect readings are obtained the key unit is faulty and must be replaced About the other pads the above method may be used Reconnect all leads removed from components during testing Re install the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions 18 TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Fo pL 5 4 3 Her 7 6 J LEVEL AF GROUND Sore eas Key unit ribbon cable
56. not to operate the oven and 2 contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration s Center for Devices and Radiological Health immediately Service personnel should inform SHARP ELECTRONICS CORPORATION of any certified unit found with emissions in excess of 4mW cm The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance R 520LK R 520LW WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of pro ducing very high voltage and current contact with following parts may result in a severe possibly fatal electrical shock Example High Voltage Capacitor High Voltage Power Transformer Magnetron High Voltage Rectifier Assembly High Voltage Harness etc Read the Service Manual carefully and follow all instructions Before Servicing 1 Disconnect the power supply cord e and then remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor WARNING RISK OF ELECTRIC SHOCK DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING The high voltage capacitor remains charged about 60 seconds after the oven has been switched off Wait for 60 seconds and then short circuit the connection of the high voltage capacitor that is the connecting lead of the high voltage rectifier against the chassis with the use of an insulated screwdriver Whenever troubleshooting is performed the power supply must b
57. ocedures B An approved microwave survey meter should be used to assure compliance with proper microwave radiation emission limitation standards After any service make sure of the following 1 Door latch heads smoothly catch latch hook through latch holes and that latch head goes through 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 microwave survey meter Refer to Microwave 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 This function does not require that door be air tight moisture condensation tight or light tight Therefore occasional appearance of moisture light or sensing of gentle warm air movement around oven door is not abnormal and do not of themselves indicate a leakage of microwave energy from oven cavity 35 R 520LK R 520LW Upper Oven Hinge Lower lt Oven Hinge Lower Oven Hinge Choke Cover Note When carring out any repair to the door do not bend or wrap the slit choke tabs on the door panel assembly to prevent microwave leakage SEALER FILM Installation 1 Put the adhes
58. ock switch and door sensing switch Cavity temperature fuse 150 C Magnetron Turntable motor Power transformer Power supply cord Magnetron temperature fuse Noise filter unit 20 250V AC V 52300 Base plate Foot Outer case cabinet Outer case cabinet R 52Z0 14 R 520LW Control unit assy Control panel R 520LK Control panel R 520Lw Key sheet assy R 520LK Key sheet assy R 520LW Open button assy R 520LK Open button assy R 520LW Open button spring Screw 3mm x 6mm Rubber connector LED sheet LCD PWB support angle Key fixing mold Capacitor band Chassis support Latch hook Switch lever Magnetron duct Fan blade Fan duct Oven cavity Not a replaceable part Waveguide cover Turntable motor packing Cushion Noise unit angle 2 Door frame Door frame Latch head Latch spring Door panel PRPRPRERPRPRPENRPRPREHEE PRPRPRPRPORRPRPRRPREER PREP RPP AQ AM AL AF AF BC AL BA AM Ak AM Sealer film Choke cover Door stopper Door glass R 520LK Door glass R 520LW Door glass stopper Door cushion Door screw PSHEPBO16MREO 4 LSTPPBO45MRFO PGLSPB118MREO PGLSPB124MREO LSTPPBO3 6MRFO PCUSUBO58MRPO KEEPS 30P06XKS0 lt lt lt lt lt lt lt lt US 4 5 39 R 520LK R 520LW 1 2 3 4 5 6 7 8 FW VZB268MREO FROLPBO25MRKO NTNT AO 9
59. om the oven cavity and sensor NOTE During this first stage do not open the door or touch STOP CLEAR pad 4 When the sensor detects the vapor emitted from the food the display switches over to the remaining cooking time and the timer counts 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 transformer oven lamp etc are turned off 6 Opening the door or touching the STOP CLEAR pad the time of the day will reappear on the display and the oven will revert to an OFF condition When the timer reaches zero an audible signal sounds R 520LK R 520LW R 520LK R 520LW Note Indicates component SCHEMATIC NOTE CONDITION OF OVEN 1 Door Closed 2 CLOCK APPEARS ON DISPLAY CAVITY MAGNETRON TEMPERATURE TEMPERATURE ORG FUSE RED FUSE ORG paisg peus RED RED DOOR SENSING SWITCH BLK POWER TRANSFORMER O h RY2 SECONDARY INTERLOCK RELAY HUMIDITY SENSOR iS To SOURCE TO LOAD i rud MAGNETRON MONITOR FUSE 20A CONTROL UNIT 60Hz OVEN To 0 0000 LAMP CAPACITOR RELAY xx uF UO o VOLTAGE RECTIFIER u NOISE 5 gt FILTER 9 o 9 e 2 _ GRY WHT WHT PRIMARY WHT INTERLOCK N
60. onit s backside Remove the turntable motor 6 Remove one 1 screw holding turntable motor to oven cover by snipping off the material in four corners cavity 4 Where the corners have been snipped off bend corner Now the turntable motor is free areas flat No sharp edges must be evident after removal After replacement use the one 1 screw provided with of the turntable motor cover the TTM Kit to attach the turntable motor cover pers 32 R 520LK R 520LW COOLING FAN MOTOR REMOVAL REMOVAL CAUTION 1 Disconnectthe power supply cord and then remove outer Do not reuse the removed fan blade because the case hole for shaft may be larger than normal 2 Open the door and block it open 3 Discharge high voltage capacitor INSTALLATION 4 Disconnect the wire leads from the fan motor 1 Install the fan blade to the fan motor shaft according to 5 Remove the two 2 screws holding the fan motor to the the following procedure oven cavity back plate 2 Hold the center of the bracket which supports the shaft 6 Remove the fan blade from the fan motor shaft according of the fan motor on the flat table to the following procedure 3 Apply the screw lock tight into the hole for shaft of the 7 Hold the edge of the rotor of the fan motor by using a fan blade pair of groove joint pliers 4 Install the fan blade to the shaft of fan motor by pushing the fan blade with a small light weight ball peen hammer Make sure that no metal pie
61. ormance standard for microwave ovens 21 CFR 1030 10 c 3 i must be used for testing 2 Place the oven tray in the oven cavity 3 Place the load of 275 15 ml 9 8 oz of tap water initially at 20 5 C 68 F in the 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 Power Cooking Mode 5 Close the door and select a cook cycle of several minutes If the water begins to boil before the survey is completed replace it with 275 ml of cool water C Leakage test Closed door leakage test microwave measurement 1 Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven 2 Move the probe slowly not faster than 1 in sec 2 5 cm sec along the gap watching for the maximum indication on the meter 3 Check for leakage at the door screen sheet metal seams and other accessible positions where the continuity of the metal has been breached eg around the switches indicator and vents While testing for leakage around the door pull the door away from the front of the oven as far as is permitted by the closed latch assembly 4
62. oven face plate Secure transformer with four screws to bottom plate Re connect wire leads primary and high voltage to power transformer and filament leads of transformer to magnetron and high voltage capacitor Refer to PICTORIAL DIAGRAM on page 30 Re install outer case and check that oven is operating properly HIGH VOLTAGE RECTIFIER AND HIGH VOLTAGE CAPACITOR REMOVAL Disconnectthe power supply cord and then remove outer Case Open the door and block it open Discharge high voltage capacitor Disconnect the high voltage wire A from the high voltage capacitor Disconnect the high voltage wire of high voltage rectifier assembly from the magnetron Disconnect the filament lead short one of the power transformer from the high voltage capacitor T 8 9 Remove 1 screw holding capacitor holder with the high voltage rectifier to the base plate Disconnect rectifier terminal from capacitor High voltage rectifier assembly is now free Remove capacitor holder Capacitor is now free CAUTION WHEN REPLACING HIGH VOLTAGE REC TIFIER AND HIGH VOLTAGE CAPACITOR GROUND SIDE TERMINAL OF THE HIGH VOLTAGE RECTIFIER MUST BE SECURED FIRMLY WITH A GROUNDING SCREW MAGNETRON REMOVAL Removal 1 Disconnectthe power supply cord and then remove outer O O case Open the door and block it open Discharge high voltage capacitor Disconnect wire leads from magnet
63. pad two figures or more are displayed c When touching the pads sometimes a pad produces no signal 17 R 520LK R 520LW TEST PROCEDURES COMPONENT TEST 2 Control Unit The following symptoms indicate a defective control unit 2 1 In connection with pads a When touching the pads a certain group of pads do not produce a signal b When touching the pads no pads produce a signal 2 2 n connection with indicators a At a certain digit all or some segments do not light up b At a certain digit brightness is low c Only one indicator does not light d The corresponding segments of all digits do not light up or they continue to light up e Wrong figure appears f A certain group of indicators do not light up g The figure of all digits flicker 2 3 Other possible problems caused by defective control unit a Buzzer does not sound or continues to sound b Clock does not operate properly C Cooking is not possible If the Key unit or the Control unit is defective 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 Replace the Control unit assembly 5 Reconnect all leads removed from components during testing 6 Re install the outer case cabinet 7 Reconnect the power supply cord after the outer case is installed 8 Run the oven and check all functions When testing is completed 1 Disco
64. pen no high voltage will be available to the magnetron Disconnect input leads Discharge high voltage capacitor and check for short or open between the terminals using an ohmmeter Checking with a high ohm scale if the high voltage capacitor is normal the meter will indicate continuity for a short time and should indicate an open circuit once the capacitor is charged If the above is not the case check the capacitor with an ohmmeter to see if it is shorted between either of the terminals and case If it is shorted replace the capacitor Reconnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions CAVITY TEMPERATURE FUSE TEST RON ONAN Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor continuity check across the cavity temperature fuse terminals should indicate a closed circuit unless the temperature of the cavity temperature fuse reaches approximately 302 F 150 C An open cavity temperature fuse indicates overheating of the oven exchange the cavity temperature fuse 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 and air guide Reco
65. pen circuit with the door open and a closed circuit with the door closed If improper operation is indicated replace the primary interlock switch Reconnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions SECONDARY INTERLOCK SYSTEM TEST DOOR SENSING SWITCH Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Isolate the switch and connect the ohmmeter to the common COM and normally open NO terminal of the switch The meter should indicate an open circuit with the door open and a closed circuit with the door closed If improper operation is indicated replace the door sensing switch Reconnect all leads removed from components during testing Heinstall the outer case cabinet Heconnect the power supply cord after the outer case is installed Run the oven and check all functions ROD O O1 PPMS NOTE If the door sensing switch contacts fail in the open position and the door is closed the cooling fan turntable and oven light will be activated by SECONDARY INTERLOCK RELAY RY2 Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Disconnect two 2 wire leads from the male tab termina
66. ron Remove the two 2 screws holding the chassis support to the magnetron and the oven cavity front flange Slide the magnetron duct slightly so that the two 2 screws at left hand side of the magnetron appear Carefully remove the four 4 screws holding magnetron to waveguide flange Remove the magnetron with care so that the magnetron antenna is not hit by any metal object around the antenna Now the magnetron is free 30 Re install 1 2 3 4 D Re install the magnetron to waveguide flange with care to prevent damage to the magnetron antenna Secure the magnetron with the four 4 screws Hold the chassis support to the oven cavity front plate and the magnetron with the two 2 screws Reconnect the wire leads to the magnetron Refer to PICTORIAL DIAGRAM on 30 Re install outer case and check that the oven 15 operating properly CAUTION WHEN REPLACING MAGNETRON BE SURE THE GASKET IS IN PLACE AND MOUNT ING SCREWS ARE TIGHTENED SECURELY R 520LK R 520LW OVEN LAMP AND LAMP SOCKET REMOVAL 1 Disconnect the power supply cord and remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Remove the oven lamp from the oven lamp socket 5 Pullthe wire leads from the oven lamp socket by pushing _ the terminal hole of the oven lamp socket with the small flat type screw driver 6 Remove the oven lamp socket from th
67. s removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL SO DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE ROD COON O O1 14 PROCEDURE LETTER R 520LK R 520LW TEST PROCEDURES COMPONENT TEST HIGH VOLTAGE RECTIFIER TEST RON po LO vi Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Isolate the rectifier from the circuit Using the highest ohm scale of the meter read the resistance across the terminals and observe reverse the leads to the rectifier terminals and observe meter reading If a short is indicated in both directions or if an infinite resistance is read in both directions the rectifier is probably defective and should be replaced Reconnect all leads removed from components during testing Heinstall the outer case cabinet Heconnect the power supply cord after the outer case is installed Run the oven and check all functions NOTE Be sure to use an ohmmeter that will supply a forward bias voltage of more than 6 3 volts HIGH VOLTAGE CAPACITOR TEST 1 COON O Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 4 the capacitor is o
68. stall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions MICROWAVE OUTPUT POWER The following test procedure should be carried out with the microwave oven in a fully assembled condi tion outer case fitted HIGH VOLTAGES ARE PRESENT DURING THE COOK CYCLE SO EXTREME CAUTION SHOULD BE OBSERVED Power output of the magnetron can be measured by performing a water temperature rise test This test should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following components or wiring silicon rectifier high voltage capacitor and power transformer This test will require a 16 ounce 453cc measuring cup and an accurate mercury thermometer or thermocouple type temperature tester For accurate results the following procedure must be followed carefully OO O gt 1 Fill the measuring cup with 16 oz 453cc of tap water and measure the temperature of the water with a thermometer or thermocouple temperature tester Stir the thermometer or thermocouple through the water until the temperature stabilizes Record the temperature of the water 2 Place the cup of water in the oven Operate oven at POWER 10 HIGH selecting more than 60 seconds cook time Allow the water to heat for 60 seconds measuring with a stop watch second hand of a watch or the digital read out countdown 3 Remove the cup from the oven and again m
69. the circuit with your hand or an uninsulated tool while the power supply is con nected When troubleshooting the microwave oven it is helpful to follow the Sequence of Operation in performing the checks Many of the possible causes of trouble will require that a specific test be performed These tests are given a procedure letter which will be found in the Test Procedure section IMPORTANT the oven becomes inoperative because of a blown monitor fuse check the monitor switch relay RY 1 secondary interlock relay RY2 door sensing switch and primary interlock switch before replacing the moni tor fuse If the monitor fuse is replaced the monitor switch must also be replaced Use part FFS 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 Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge high voltage capacitor Disconnect the leads to the primary of the power transformer 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 ok Q When the testing is completed Disconnect the power supply cord and then remove outer case Open the door and block it open Discharge hig
70. wire lead to the monitor switch COM terminal and check the continuity of the monitor circuit Reconnect all leads removed from components during testing Reinstall the outer case cabinet Reconnect the power supply cord after the outer case is installed Run the oven and check all functions S crew Driver Ohmmeter Primary Interlock S witch Monitor S witch TOUCH CONTROL PANEL ASSEMBLY TEST 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 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 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 the outer case is installed 3 Run the oven and check all functions The following symptoms indicate a defective key unit a When touching the pads a certain pad produces no signal at all b When touching a number

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