Sharp R-8R51 - Page 17

We
R-8RS1(W)
R-8R51(8)
TEST PROCEDURES (CONT’D)
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 + 2) K.
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.
| Initial temperature (T1 = 11°C
uel
Temperature after IT2 = 21°C
(49 + 2) = 51 sec.
Temperature difference Cold-Warm | AT = 10°C
Mean temperature rise AT | =
Measured output power P= 85x10°C |
The equation is as follows: = 850 Watts
P= 85 x AT
JUDGMENT: The measured output power should be at least +15 % of the rated
output power.
CAUTION: 1°C CORRESPONDS TO 85 WATTS. REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
HAWINIHH
—
=
=
—
—
a
|
|
Heat up for 51 sec.
B POWER TRANSFORMER TEST
WARNING:
High
voltages
and
large
currents
are
present
at
the
secondary
winding
and
filament
winding
of
the
power transformer.
It
is
very
dangerous
to
work
near
this
part
when
the
oven is
on.
NEVER
make
any
voltage
measurements at the high-vitage circuits, including the magnetron fila-
ment.
CARRY OUT 3D CHECKS.
Disconnect
the
jeads
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 ---------- 0.94 ohms approximately.
b. Secondary winding ------- 61.6 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
15