Sharp R-742IN Service Manual Download Page 21 | Manualshive

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R-742

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Summary of Contents for R-742IN

Page 1: ...HINGS TO DO PRIOR CHAPTER 13 SAFTY CHEC S AND TESTS AFTER CHAPTER 14 Parts List MICROWAVE OVEN SERVICE MANUAL MODEL CONTENTS SHARP CORPORATION This document has been published to be used for after sales service only The contents are subject to change without notice In interests of user safety the oven should be restored to its original condition and only parts identical to those specified should b...

Page 2: ...or 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 C 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 D Any defective or misadjus...

Page 3: ...AM 4 1 CIRCUIT DESCRIPTION 4 2 SERVICE INFORMATION 5 1 TOOLS AND MEASURING INSTRUMENTS 5 1 MICROWAVE LEAKAGE TEST 5 2 MEASUREMENT OF MICROWAVE POWER OUTPUT 5 3 TROUBLE SHOOTING PROCEDURES 5 4 COMMON BREAKDOWN AND MEANS OF REPAIRING 5 8 IMPORTANTTHINGSTODOPRIORTOCRITICALPARTSERVICING 5 9 SAFETY CHECKS AND TESTS AFTER SERVING 5 10 EXPLODED VIEW 6 1 REPLACEMENT PARTS LIST 6 1 ...

Page 4: ...latch hole and the interlock switches area Unlike other appliances the microwave oven is high voltage and high current equipment Though it is free from danger in ordinary use extreme care should be taken during repair MICROWAVE RADIATION Personnel should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating device if it is improperly used or conn...

Page 5: ...gth among the molecule and changed to microscopic microwave heating Microwave heating not only concerned the nature of the matter itself but also closely connected with the electric field strength and frequency When the frequency is low the molecule swaying rate and the acute degree of the mutual friction among the molecule is low and would produce much heat When the frequency is too high as the s...

Page 6: ... and flat surface at least 10 cm 4 inches from the wall 7 Place the microwave oven as far away as possible from TV RADIO COMPUTER etc to prevent interference BEFORE YOU BEGIN READ THE FOLLOWING INSTRUCTIONS COMPLETELY EARTHING INSTRUCTIONS This microwave oven is designed to be used in a fully earthed condition It is imperative therefore to make sure it is properly earthed before servicing WARNING ...

Page 7: ...SCHEMATIC DIAGRAM ...

Page 8: ...ir is also directed into the oven to exhaust the vapor in the oven through the upper plate Timer starts rotating 3 2 volts AC is generated from the filament winding of the high voltage transformer This 3 2 volts is applied to the magnetron to heat the magnetron filament through two noise preventing choke coils A high voltage of approximately 2100 volts AC is generated in the secondary of the high ...

Page 9: ...microwave leakage Check for microwave leakage after every servicing The power density of the microwave radiation leakage emitted by the microwave oven should not exceed 5 mW cm2 Always start measuring of an unknown field to assure safety for operating personnel from radiation leakage NECESSARY MEASURING INSTRUMENTS TESTER VOLTS DC AC Ohmmeter Microwave survey meter Holaday HI 1710 A Narda 8100 820...

Page 10: ...an 1 inch sec 2 5 cm sec along the shaded area otherwise a false reading may result The test probe must be held with the grip portion of the handle A false reading may result if the operator s hand is between the handle and the probe When testing near a corner of the door keep the probe perpendicular to the surface making sure the probe horizontally along the oven surface this may possibly cause p...

Page 11: ...d on the center of the turntable which is in the lowest position and the microwave power switched on The time T for the temperature of the water to rise by a value T of 10 2 K is measured where T is the time in seconds and T is the temperature rise The initial and final water temperatures are selected so that the maximum difference between the final water temperature and the ambient temperature is...

Page 12: ...nce Measure the insulating resistance with a multi meter or a mega ohmmeter The value should not less than 2 mega ohm Otherwise part examination should be taken at once Such as checking whether the motor the thermal cutout the transformer or the capacitor are electricity leaking 2 Examination of the resistance value of the microwave oven Close the door set the time the oven is at operating conditi...

Page 13: ...citor pole and the cabinet FIG 5 6 should be checked If the resistance value between the capacitor pole and the cabinet is the capacitor is normal Then check the earth of the magnetron s two filament to see whether they are short circuited FIG 5 7 If they are short circuited and the filament strikes the shell of the magnetron it indicates the magnetron has broken and should be replaced by a new sa...

Page 14: ...st the upper screw Loosen out the screw push the door close to the oven to hook the door hook with the plastic parts then tighten the screw again If the leakage is larger at the right below then adjust the lower screw Loosen the screw push the door close to the oven to hook the door hook with the switch holder tightly then tighten the screw again and open and close the door repeatedly to check whe...

Page 15: ...l cutout is playing its protective role and you should check whether the fan is working in normal Turn off the oven pull out the power plug take down the outer case discharge the capacitor then turn the fan with hand to see whether it is moving flexibly If not it indicates that the oil bearing of the fan motor has run off the oil and should take down the fan combination to repair the motor Loosen ...

Page 16: ... Turntable Motor Wire leads removed Measure the resistance Ohm meter scale R 1000 Normal Approx 3 2kΩ Abnormal or Several Ω NOTE z A MICROWAVE LEAKGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON z MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION z WHEN REMOVING THE WIRE LEADS FROM THE PARTS BE SURE TO GRASP THE CONNECTOR NOT THE WIRES 5 8 ...

Page 17: ...2 Insert the plug securely 3 Change the weave 5 The oven can heat within 2 3 minutes but can not heat from the fourth minutes 1 The winding of the fan motor in open circuited 2 The fan falls off 3 The plug of the fan motor falls off 4 The turntable shaft is griped with the motor bearing 5 The cooling vent blocked 1 Change the fan motor 2 Change the fan 3 Insert the plug 4 Overhauling them 5 Repair...

Page 18: ...eck the electrical continuity 2 2 Make sure the power cord is pulled out and the high voltage capacitor is discharged before the electrical continuity check 2 3 Set the ohmmeter to Low Resistance range and connect both leads alligator clips to the switch terminals 2 4 Open the door and notice the meter reading The primary or secondary interlock switch should show an infinite resistance when the do...

Page 19: ...1 3 Check the following items before turning the oven ON 1 Proper door closing seal choke surfaces and hinges 2 No outer case damage 3 Proper interlock and monitor operations Insulation Resistance Test If the low voltage power supply has been repaired use a 500 V Mega ohmmeter to measure the resistance between the primary Line and Neutral of the power plug and operator accessible metal parts The r...

Page 20: ...ECO MEMBRAN R 742 ...

Page 21: ...R 742 ...

Page 22: ... D05 252200400382 BARRIER SCREEN I 1 E25L PET D06 262100402833 BARRIER SCREEN O 1 D07 261300141102 PANEL DOOR 1 E25L White D08 256300600075 GASKET DOOR 1 E28L Black D16 261301805205 HOLDER HANDLE 1 E28L HE D54 261356101901 COVER HANDLE 1 E25L HE White E01 251200100068 MAGNETRON 1 2M219J 900W E05 251200200337 H V TRANSFORMER 1 E06 251200701304 H V CAPACITOR 1 CH85 1 05uF 2100V E07 251200900861 H V ...

Page 23: ...00001 MOTOR TRAY 1 TYJ50 8A7 220 240V T02 252200100008 COUPLER 1 C23L PPS T03 262200200007 RING ROTATING ASS Y 1 A28L PPS T04 252100500013 TRAY 1 E25L Diameter315mm W01 261300800100 GUIDE FAN 1 C23L W02 251300900016 FAN 1 C23L W03 261200600350 MOTOR FAN 1 220 240V W04 261503202100 GUIDE WIND 1 A28L SGCC T 0 5 Z01 261501500300 HOLDER H V C 1 A23L SGCC T 0 5 Z05 251301700007 HOLDER POWER CORD 1 Z24 ...

Page 24: ...01000 SHIELD 1 SGCC T 0 5 D01 251500200108 ASS Y DOOR FRAME 1 E25L SPCD T 0 6 D02 251300502368 LATCH 1 A28L PBT D03 252010000012 SPRING LATCH 1 25L D04 256502400556 ASS Y BRKT HINGE T 1 A28L SPCC T 2 0 D05 252200400382 BARRIER SCREEN I 1 E25L PET D06 262100402833 BARRIER SCREEN O 1 D06 262100402833 BARRIER SCREEN O 1 D07 261300141101 PANEL DOOR 1 E25L Silver D08 256300600075 GASKET DOOR 1 E28L Bla...

Page 25: ...ESS MAIN 1 EG925E P00E H2 T01 251200300001 MOTOR TRAY 1 TYJ50 8A7 220 240V T02 252200100008 COUPLER 1 C23L PPS T02 252200100008 COUPLER 1 C23L PPS T03 262200200007 RING ROTATING ASS Y 1 A28L PPS T04 252100500013 TRAY 1 E25L Diameter315mm W01 261300800100 GUIDE FAN 1 C23L W02 251300900016 FAN 1 C23L W03 261200600350 MOTOR FAN 1 220 240V W04 261503202100 GUIDE WIND 1 A28L SGCC T 0 5 Z01 261501500300...

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