Sharp R-4H55 Service Manual page 13

TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value
A
T of
(10 -t 2)"C.
5. Stir the water to equalize temperature throughout the vessel.
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.
Initial temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tl = 11 'C
Temperature after (47+2)= 49 sec. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . T2 = 21 "C
Temperature difference Cold-Warm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AT1 =
10°C
Measured output power
The equation is '!P= 90 x AT"
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P= 90 x 10°C = 900 Watts
JUDGMENT: The measured output power should be at least + 15 % of the rated output
power.
CAUTION: 1 C CORRESPONDS TO 90 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
l5d
Heat up for 49 sec.
MICROWAVE OUTPUT POWER (2 Litre water load)
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (with outer case fitted).
Microwave output power from the magnetron can be measured by way of substitution, i.e. it can be
measured by using a water load how much it can be absorbed by the water load. To measure the
microwave output power in the microwave oven, the relation of calorie and watt is used.
On the other hand, if the temperature of the water with V(ml) rises AT ("C) during this microwave
heating period, the calorie of the water is V x AT.
The formulae is as follows;
P =8330xAT/t
Our condition for the water load is as follows:
Room temperature . . . . . . . . . . . . . . ...23+ 2°C
Power supply Voltage . . . . . . . . . . . . . . . . . . Rated voltage.
Water load
. . . . ...2000
ml
Initial temperature . . . . . . . 23 & 1 "C Heating time .,.. 1 min. 51 sec.
P=75xAT
Measuring method:
A) The two water containers must be prepared.
The water container must be one (1) litre beaker made of Pyrex glass and its diameter approxi-
mately 12cm.
B) Put the one (1) litre water into each beaker (Each beaker has one litre water). The initial tempera-
ture of the water should be 23-C.
C) Mark Tl on the one beaker and mark T2 on the other one. And stir the water and measure the
temperature of water the thermometer and note them. The graduation of the thermometer must be
scaled by 0.1 "C at minimum and an accurate mercury thermometer is recommended.
D) Place the two (2) beakers as touching each other in the centre of the oven cavity.
E) Set the timer to 1 minute and 51 seconds and then start the oven at HIGH.
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