Sharp R-961 (W) - Page 19

TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
Initial temperature
Temperature
after
(42
+
3)
=
45
SOC.
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T2
=
21°C
Temperature
difference
Cold-Warm
AT1
=
10°C
Measured output power
The equation is “P = 100 x AT”
JUDGMENT:
The
measured
output
power
should
be
at
least
+
15
%
of
the
rated
output
power.
CAUTION:
1°C
CORRESPONDS
TO
100
WATTS.
REPEAT
MEASUREMENT
IF
THE
POWER
IS
INSUFFICIENT.
Heat up for 45 sec.
B H T TRANSFORMER TEST
WARNING:
High
voltages
and
large
currents
are
present
at
the
secondary
winding
and
filament
winding
of
the
high
voltage
transformer.
It
is
very
dangerous
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
high
voltage
transformer.
Disconnect
the
filament
and
secondary
winding
connections
from
the
rest
of
the
HV
circuitry.
Using
an
ohmmeter,
set
ona
low
range,
it
is
possible
to
check
the
continuity
of
all
three
windings.
The
following
readings
should
be
obtained:
a. Primary winding 1.3 ohms approximately
b. Secondary winding 85 ohms approximately
c. Filament winding less than 1 ohm
if
the
reading
obtained
are
not
stated
as
above,
then
the
high
voltage
transformer
is
probably
faulty
and
should
be
replaced.
CARRY OUT 4R CHECKS.
Cc HIGH VOLTAGE RECTIFIER ASSEMBLY TEST
HIGH VOLTAGE RECTIFIER TEST
CARRY OUT 3D CHECKS.
Isolate
the
high
voltage
rectifier
assembly
from
the
HV
circuit.
The
high
voltage
rectifier
can
be
tested
using
an
ohmmeter
set
to
its
highest
range.
Connect
the
ohmmeter
across
the
terminal
B+C
ofthe
high
voltage
rectifier
and
note
the
reading
obtained.
Reverse
the
meter
leads
and
note
this
second
reading.
The normal
resistance
is
infinite in
one
direction
and
more than
100
kQ
in the
other
direci on.
CARRY OUT 4R CHECKS
ASYMMETRIC
RECTIFIER
CARRY
OUT
3D
CHECKS.
C/
HIGH
VOLTAGE
RECTFIER
ASYMMETRIC RECTIFIER TEST
R-961 - 17