R
-7A53
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
A
T
of
(IO
+
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
p
in
watts
from
above
formula.
I
Initial
temperature
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.._._......................................................................
Tl
=
11
“C
/
Temperature
after (49
+
2)
=
51
sec.
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T2
=
21
“C
Temperature
~
M
difference Cold-Warm
=
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AT1 10°C
easured
output
power
!
The
equation
is
“P=
85
x
AT”
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...’
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P= 85
x
10°C
=
850
Watts
JUDGMENT: The measured output power should be at least
f15
%
of
t?he
rated
.
output power.
CAUTION:
1°C
CORRESPONDS
TO
85
WATTS. REPEAT
MEASUREMENT
IF
THE POWER
IS
INSUFFICIENT.
1
ooog
+
T2’C
Heat
up
for
51
sec.
(RDE
\03U)
B
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
3LJ
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
following
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
probably
faulty
and
should
be
replaced.
CARRY
OUT
4R
CHECKS
6
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