Table of Contents
Advertisement
R-9ZOO
TEST
PROCEDURES
PROCEDURE
LETTER
COMPONENT
TEST
A
MAGNETRON
TEST
' NEVER TOUCH
ANY PART IN THE CIRCUIT
WITH YOUR HAND OR AN INSULATED
!-
TOOL WHILE THE OVEN IS IN OPERATION.
-1
-----
CARRY OUT 3D CHECKS
Isolate the magnetron
from the high voltage circuit
by removing
all leads connected
to the filament
terminal.
To test for an open circuit
filament
use an ohmmeter
to make a continuity
test between
the
magnetron
filament
terminals,
the meter should show a reading of less than 1 ohm.
To test for a short circuit
filament
to anode condition,
connect
ohmmeter
between
one of the fil-
ament terminals
and the case of the magnetron
(ground).
This test should
be indicated
an infinite
resistance.
If a low or zero resistance
reading is obtained
then the magnetron
should be re
(R lz
laced.
82AOl
U)
MICROWAVE
OUTPUT
POWER
(2 liter
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.
When
P(W)
heating
works for t(second),
approximately
P x t/4.2
calorie
is generated.
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 formula
is as follows;
P x t / 4.2 = V x AT
P (W) = 4.2 x V x AT/t
Our condition
for the water load is as follows:
Room temperature
. . . . . . . . . . . . . . . . . . . . . around 20°C
Power supply Voltage . . . . . . . . . . . . . Rated voltage
Water load . . . ...2000
ml
Initial temperature
. . . . . . . 1 O+ 1 "C
Heating time . . . . . . 1 min. 45 sec.
P=80xAT
Measuring
method:
A) Use two 1 litre Pyrex beakers with a diameter of approximately
of 12cms.
B) Place 1 litre of 10°C water in each beaker.
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 beakers as touching
each other in the centre of the cavity.
E) Set the timer to 1 minute and 45 seconds,
at 100% power
(the time required
to raise the water
temperature
10 degrees C.)
F) The time must be measured with stopwatch
or wristwatch.
G) After 1 minute and 45 seconds,
stop the oven by opening
the door.
H) Remove the two beakers from the oven and measure the temperature
of the water by stiring the
water with the thermometer
and noting
the readings.
Example
Initial temperature
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tl
= 10°C
T2 = 11 "C
Temperature
after 1 min. 45 set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tl
= 20°C
T2 = 21 "C
Temperature
difference
Cold-Warm
s..........................................
AT1
= 10°C
AT2
= 10°C
Mean temperature
rise AT
. . . . . . . . AT
= (AT1
+AT2)
/ 2 = (IO'C
+ IO'C)
/ 2 = 10°C
Measured
output
power
The equation
is "P= 80 x AT"
*.........t....*.*.................................
P= 80 x 10°C = 800 Watts
NOTE:
The
measured
output
power
should
be at least
+I5
% of the
rated
output
power.
CAUTION:
1 "C CORRESPONDS
TO 80 WATTS.
REPEAT MEASUREMENT
IF THE POWER IS INSUFFICIENT.
8
Advertisement
Table of Contents
