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TEST
PROCEDURES
(CONT'D)
PROCEDURE
LETTER
COMPONENT
TEST
~~~
Measuring
method:
1. Measure
the initial
temperature
of the water
before
the water
is added
to the vessel.
(Example:
The initial
temperature
Tl
= 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
D T of
(10 fr 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. Caluculate
the microwave
power
output
fl in watts
from
above
formula.
/
Initial
temperature
~..................~.......~.........................................~...............................
Tl
=ll"C
'
Temperature
after
(49
+ 2)=
51 sec. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*........................*......
T2 = 21°C
Temperature
difference
Cold-Warm
/
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AT1
=
Measured
output
power
10°C
I
The equation
is "P=
85 x
AT" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
P= 85 x 10°C
= 850 Watts
/
JUDGMENT:
The
measured
output
power
should
be at least
+I5
% of the
rated
output
power.
CAUTION:
1°C CORRESPONDS
TO 85 WATTS.
REPEAT
MEASUREMENT
IF THE
POWER
IS
INSUFFICIENT.
I)
T2'C
Heat up for 51 sec.
(RDEkA03lJ)
6
POWER
TRANSFORMER
TEST
WARNING:
High
voltages
and large
currents
are present
at the secondary
wind-
ing and filament
winding
of the
power
transformer.
It is very
dan-
gerous
to work
near this part when
the oven is on.
NEVER
make any
voltage
measurements
of
the
high-voltage
circuits,
including
the
magnetron
filament.
CARRY
OUT 3D CHECKS.
Disconnect
the leads to the primary
winding
of the power
transformer.
Disconnect
the filament
and secondary
winding
connections
from the
rest of the HV circuitry.
Using
an ohmmeter
set
on a low
range,
it is possible
to check
the
continuity
of all three
windings.
The
follo&ing
readings
should
be obtained
:-
a.
Primary
winding
----------I
.20 ohms
approximately.
b.
Secondary
winding
- - - - - - -75.5
ohms
approximately.
c.
Filament
winding
---------less
than
1 ohm.
If the reading
obtained
are not as stated
above,
then
the power
transformer
is probabiy
faulty
and should
be replaced.
CARRY
OUT 4R CHECKS
7
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