background image

 

 

 

COMMON BREAKDOWN AND MEANS OF REPAIRING 

PHENOMENON CAUSE REPAIRING 

MEANS 

 
 
 
1.When starting the 
oven, the lamp is not on, 
the turntable tray can’t 
rotate and the food can’t 
be heated 

1. fuse 

broken 

2.  The primary and secondary winding of the 

transformer are short-circuited. 

3.  The earthing or the polarity of the capacitor is 

punctured. 

4.  The pilot switch can’t cut off. 
5.  The interlock switch hasn’t closed. 
6.  The power plug and the socket are not in good 

connection. 

7.  The door hook broken. 

1.  Change a new fuse. 
2. 

Change a new 
transformer. 

3.  Change a new capacitor.
4. Change a new pilot 

switch. 

5.  Change a new interlock 

switch. 

6.  Adjust the connection or 

replace it by a new one. 

7.  Change a new book. 

2.When starting the 
oven, the lamp is on, the 
turntable rotating, the fan 
cycling but the food can’t 
be heated. 

1. The primary and secondary winding, the 

filament of the transformer are open-circuited. 

2.  The magnetron filament is open-circuited, the 

magnetic steel of the magnetron broken or the 
magnetron is air leaking. 

3.  Time and power distributor broken.. 
4.  The plugs of the magnetron of the capacitor 

loosed. 

1. 

Change a new 
transformer. 

2.  Change the magnetron. 
3.  Change the time power 

distributor or the micro-
switch. 

4. Fix 

them. 

3.The food can be 
heated, but the lamp is 
not on. 

1.  The lamp broken. 
2.  The plug fall off. 

1.  Change a new lamp 
2.  Insert the plug again 

4.The food can be 
heated but the turntable 
tray is not rotating. 

1.  The turntable motor broken 
2.  The plug fall off 
3.  Connecting shaft weave broken 

1. Change the turntable 

motor 

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. Repairing 

it 

6.When starting the 
oven, it can’t heat, and 
with “wenwen” noise 

The high voltage diode was punctured 

Change a new diode 

7.The oven can heat,but 
with sound “shishi” noise 

The iron core of the transformer loosed 

Change a new transformer 

8.Large amount of 
microwave leakage 

1.  The door deformed 
2.  The door metal net cracked 
3.  The gap of the door crack is too large 
4.  The welding point of the oven fall off 
5.  The screws which fix the magnetron loosed 
6.  The wave guide connection oxidized 
7.  The magnetron copper filament washer is too 

thin cause the wave guide opening not in good 
earth. 

1.  Mend the door 
2.  Change the door 
3.  Adjust the gap 
4.  Change the oven 
5.  Tighten the screws 
6.  Scrape the oxidized and 

tighten the screws 

7.  Thick the copper filament 

washer 

9.The door can’t open 

1.  After  long  time using, the wear and the rust-

eaten enlarged the gap of the door shaft and 
the shaft hole, thus cause the door crooked. 

2.  The door hook broken 

1.  Adjust the hinge to rectify 

the position of the door. 

2.  Change the hook 
 

10.The door release 
button fall off 

Wore aged after long time operating 

Overhaul it or renew it 

11.Electricity leaking 

The  earthing  insulation resistances of all the 
motors or the transformer are less than 2 mega 
ohm. 

Test where is the leaking 
place, then repair it or 
change those damaged 
components. 

 

5-9

Содержание R-742IN

Страница 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...

Страница 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...

Страница 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 ...

Страница 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...

Страница 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...

Страница 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 ...

Страница 7: ...SCHEMATIC DIAGRAM ...

Страница 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 ...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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 ...

Страница 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 ...

Страница 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...

Страница 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...

Страница 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...

Страница 20: ...ECO MEMBRAN R 742 ...

Страница 21: ...R 742 ...

Страница 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 ...

Страница 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 ...

Страница 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...

Страница 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...

Отзывы: