Read Sharp R-21ATP Service Manual online
8
R-21ATP
B
HIGH VOLTAGE TRANSFORMER TEST
WARNING:
High voltage and large currents are present at the secondary winding and
filament winding of the high voltage transformer. It is very dangerous to work
near this part when the oven is on. NEVER make any voltage measurements
of the high-voltage circuits, including the magnetron filament.
filament winding of the high voltage transformer. It is very dangerous to work
near this part when the oven is on. NEVER make any voltage measurements
of the high-voltage circuits, including the magnetron filament.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
Measuring condition:
1. Container
1. Container
The water container must be a cylindrical borosilicate glass vessel having a maximum material
thickness of 3 mm and an outside diameter of approximately 190 mm.
thickness of 3 mm and an outside diameter of approximately 190 mm.
2. Temperature of the oven and vessel
The oven and the empty vessel are at ambient temperature prior to the start the test.
3. Temperature of the water
The initial temperature of the water is (10
±
1)
°
C.
4. Select the initial and final water temperature so that the maximum difference between the final water
temperature and the ambient temperature is 5
°
C.
5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
6. The graduation of the thermometer must be scaled by 0.1
6. The graduation of the thermometer must be scaled by 0.1
°
C at minimum and be an accurate
thermometer.
7. The water load must be (1000
±
5) g.
8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heat-
up time is not included.
NOTE: The operation time of the microwave oven is “t + 3” sec. (3 sec. is magnetron filament heat-up time.)
Measuring method:
1. Measure the initial temperature of the water before the water is added to the vessel.
1. Measure the initial temperature of the water before the water is added to the vessel.
(Example: The initial temperature T1 = 11
°
C)
2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value
∆
T of
10˚C.
5. Stir the water to equalize temperature throughout the vessel.
6. Measure the final water temperature. (Example: The final temperature T2 = 21
6. Measure the final water temperature. (Example: The final temperature T2 = 21
°
C)
7. Calculate the microwave power output P in watts from above formula.
Room temperature ....................... To = 21˚C
Initial temperature .................... T1 = 11
°
C
Temperature after (42 + 3) = 45 sec. ..................................................................... T2 = 21
°
C
Temperature difference Cold-Warm ....................................................................
∆
T1 = 10
°
C
Measured output power
The equation is “P = 100 x
The equation is “P = 100 x
∆
T” ................................................ P = 100 x 10
°
C = 1000 Watts
JUDGMENT: The measured output power should be at least
±
15 % of the rated output power.
CAUTION: 1
°
C CORRESPONDS TO 100 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
Heat up for 45 sec
1000g
1000g
1000g
T1˚C
T2˚C
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