Sharp R-722STM Service Manual page 15

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If there still exist microwave leakage, measure near the magnetron with the probe of the microwave leakage measure. If
the leakage is larger, the oven should be turned off and check whether the 2 or 4 screws which fix the magnetron have
been loosed, if loosed, twist them tightly with socket wrench. If the screws are fixedly, then the magnetron should be
take down to check the copper filament weaved washer of the magnetron has been placed well or whether the wave
guide housing coupling has been oxidized or have lacquer on it. If do have, scrape the oxidized layer or the lacquer off,
when fix the magnetron, the copper filament weaved washer must be placed well, the screws must be twist tightly. Then
turn on the oven and measure again until it complies with the requirement. If the microwave leakage is larger at those
hole position of the window board, the oven should be turned off to inspect whether there are crack among them. If
several holes formed a crack, it would enlarge the microwave leakage. If that is the case, it indicates the door has
broken, and should be replaced with a new door.
2.
Means of repair when the oven can heat, but the turntable glass can't move
Firstly, check whether the turntable holder is placed correctly. If it is correct, then pull out the power plug and take down the
turntable combination, measure the resistance value of the turntable motor with Rx1k grade of a multi meter If it is open-
circuited, it indicates the turntable motor has broken, and should be replaced by a new, same model one. If the resistance
value is between 15-22k,it indicates the turntable motor is normal, then check the connecting shaft weave. If the plastic that
the shaft insert in has broken, a new shaft weave should replace it.
3.
Repair when the oven can heat, but the lamp is not on.
Pull out the power plug, take down the outer case and discharge the capacitor.
Pull out the two terminal plugs of the lamp, measure the two plugs of the lamp with the Rx100 grade of a multi meter. If it is
open-circuited, it indicates the lamp has broken, and should be replaced by a same model one.
4.
Means of repair when the oven stop working after several minutes operating
The phenomenon indicated the thermal 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 the two screws which fix the bearing out the shaft and the bearing,
and rinse them with kerosene (ATTENTION: The bearing can only be wiped with a silk which moistened with kerosene rather
than be washed in the kerosene because there are felt on it. If the felt are soaked with kerosene, then the engine oil can not
be sucked up.).After the bearing being cleaned, the felt should be refueled fully with engine oil(for when the oven is operating,
the engine oil empty into the oil bearing slowly).Fix the bearing cover with two screws, turn the fan around till it can move
flexibly. Than install them to the oven, and plug in the two terminal plugs.
If the fan can move flexibly, then the winding of the fan motor should be examined. Measure the winding with Rx100 grade of
a multi meter, if it is open-circuited, it indicates the winding of the fan motor has broken, and should be replaced by a new,
same model one.
5-7

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