Read Sharp R-242M Service Manual online
6
R-242M -
MICROWAVE OUTPUT POWER (IEC-705)
The power output of this oven is rated using the method specified by IEC-705. Full details of how to carry out this
procedure can be found in the Sharp Technical Training notes which is available from Sharp Parts Centre
(part number SERV-LITMW01).
procedure can be found in the Sharp Technical Training notes which is available from Sharp Parts Centre
(part number SERV-LITMW01).
Using this procedure, the heating time to raise 1000g of water by 10
°
C is approximately 50 seconds.
The IEC-705 procedure must be carried out using laboratory-type procedures and equipment. These requirements
make the procedure unsuitable for routing performance checks. An indication of the power being produced by the oven
can however be obtained using the procedure given below.
make the procedure unsuitable for routing performance checks. An indication of the power being produced by the oven
can however be obtained using the procedure given below.
Alternative simplified method:
1. Place 2 litres of cold water (between 12
1. Place 2 litres of cold water (between 12
°
C and 20
°
C) in a suitable container.
2. Stir the water and measure the temperature in
°
C. Note temperature as T1.
3. Place the container in the microwave and heat the water for 2 minutes on full power.
4. When the 2 minutes is completed, remove the container and stir the water. Note the water temperature as T2.
5. Calculate the output power using the following formula:
4. When the 2 minutes is completed, remove the container and stir the water. Note the water temperature as T2.
5. Calculate the output power using the following formula:
R.F. Power Output = (T2 - T1) x 70.
Note: The result from this test should be within 10% of the power rating stated on the rating label.
MICROWAVE LEAKAGE TEST
This oven should be tested for microwave leakage on completion of any repair or adjustment, following the procedure
described in the Sharp Technical Training notes (part number SERV-LITMW01). The maximum leakage permitted in
BS EN 60335-2-25 is 50W/m
described in the Sharp Technical Training notes (part number SERV-LITMW01). The maximum leakage permitted in
BS EN 60335-2-25 is 50W/m
2
(equivalent to 5mW/cm
2
), however it is not normal to detect any significant leakage,
therefore, any leakage which is detected should be investigated.
It is essential that only leakage detectors with current calibration traceable to the National Physical Laboratories are used.
Suitable leakage detectors :
CELTEC A100
APOLLO X1
APOLLO X1
OUTPUT POWER TEST PROCEDURE
THERMAL CUT-OUT 125˚C (OVEN)
The thermal cut-out located on the top of the oven cavity is
designed to prevent damage to the oven, if the food in the
oven catch fire due to over heating produced by improper
setting of cook time or failure of control unit. Under normal
operation, the thermal cut-out remains closed. However,
when abnormally high temperatures are reached within the
oven cavity, the thermal cut-out will open at 125˚C, causing
the oven to shut down. The defective thermal cut-out must be
replaced with a new one.
designed to prevent damage to the oven, if the food in the
oven catch fire due to over heating produced by improper
setting of cook time or failure of control unit. Under normal
operation, the thermal cut-out remains closed. However,
when abnormally high temperatures are reached within the
oven cavity, the thermal cut-out will open at 125˚C, causing
the oven to shut down. The defective thermal cut-out must be
replaced with a new one.
TURNTABLE MOTOR
The turntable motor drives the turntable roller assembly to
rotate the turntable.
rotate the turntable.
FAN MOTOR
The fan motor drives a blade which draws external cool air.
This cool air is directed through the air vanes surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and vapours
given off from heating food. It is then exhausted through the
exhaust vents at the rear of the oven cavity.
This cool air is directed through the air vanes surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and vapours
given off from heating food. It is then exhausted through the
exhaust vents at the rear of the oven cavity.
NOISE FILTER
The noise filter assembly prevents radio frequency interfer-
ence that might flow back into the power circuit.
ence that might flow back into the power circuit.
OPERATING SEQUENCE
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