Sharp R-4P58 - Page 12

——_: - os
circuited,
this
fuse
E2
blows
to
prevent
an
electric
shock
of
fire
hazard.
FUSE E3 F8A 250V
1.
Ifthe
wire
harness
or
electrical
components
are
short-
circuited,
this
fuse
F3
blows
to
prevent
an
electric
shock
of
fire
hazard.
2.
The
fuse
F3
also
blows
when
asymmetric
rectifier,
H.V.
rectifier,
H.V.
wire
harness,
H.V.
capacitor,
magnetron
or
secondary
winding
of
high
voltage
transformer
is
shorted.
ASYMMETRIC RECTIFIER
The
asymmetric
rectifier
is
a
solid
state
device
that
pre-
vents
current
flow
in
both
directions.
And
it
prevents
the
temperature
rise
of
the
high
voltage
transformer
by
blow-
ing
the
fuse
F3
F8A
when
the
high
voltage
rectifier
Is
shorted.
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE RECTIFIER
The
rated
peak
reverse
voltage
of
D1
of
the
asymmetric
rectifier
is
6
KV.
The
rated
peak
reverse
voltage
of
D2
of
the
asymmetric
rectifier
is
1.7
KV.
D1
and
D2
of
the
asymmetric
rectifier
or
high
voltage
rectifier
are
shorted
when
the
each
peak
reverse
voltage
goes
beyond
the
each
rated
peak
reverse
voltage.
(The
process
of
blowing
the
fuse
F3
F8A.)
1.
The
high
voltage
rectifier
is
shorted
by
any
cause
when
microwave
cooking.
2.
The
peak
reverse
voltage
of
D2
of
the
rectifier
goes
beyond
the
rated
peak
reverse
voltage
1.7
KV
in
the
voitage
doubler
circuit.
3. D2 of the rectifier is shorted.
4,
The
large
electric
currents
flow
through
the
high
voit-
age
winding
of
the
high
voliage
transformer.
5.
The
large
electric
currents
beyond
8A
flow
through
the
primary
winding
of
the
high
voltage
transformer.
6.
The
fuse
F3
blows
by
the
large
electric
currents.
7.
The
power
supply
to
the
high
voltage
transformer
is
cut
off.
THERMAL CUT-OUT TC4 125°C (MG)
This
thermal
cut-out
protects
the
magnetron
against
over-
heating. If the temperature goes up higher than 125°C
because
the
fan
motor
is
interrupted
or
the
ventilation
openings
are
blocked,
the
thermal
cut-out
[C1
will
open
and line voltages to the high voltage transformer will be cut
off
and
the
operation
of
the
magnetron
will
bestopped.
The
thermal cut-out will cut back in at 95°C.
THERMAL CUT-OUT TG2 150°C (OVEN)
The thermal cut-out located on the side of the air guide
ductis designed to prevent damage to the oven ifthe foods
in the oven catch fire due to over heating produced by
improper
setting
of
the
cooking
time
or
failure
of
control
unit.
Under
the
normai
operation,
the
oven
thermal
cut-out
TC2
remains
closed.
However,
when
abnormally
high
temperature are reached within the oven cavity, oven
thermal cut-out TC2 will open at 150°C causing the oven
io
shut
down.
The
thermal
cut-out
will
cut
back
in
at
120°C.
TURNTABLE MOTOR TTM
The turntable motor drives the turntable rojler assembly to
rotate the turntable.
FAN MOTOR EM
The
fan
motor
drives
ablade
which
draws
external
cool
air.
This
cool
air
is
directed
through
the
air
vanes
surrounding
the
magnetron
and
cools
the
magnetron.
This
air
is
chan-
nelled
through
the
oven
cavity
to
remove
steam
and
vapours
given
off
from
heating
food.
It
is
then
exhausted
through
the
exhausting
air
vents
of
the
oven
cavity.
NOISE FILTER
The
noise
filter
assembly
prevents
radio
frequency
inter-
ference
that
might
flow
back
in
the
power
circuit.
GRILL
HEATING
ELEMENT
(TOP
GRILL)
GH1
The grill heating element GH71 is located on the top of the
oven
cavity
assembly.
The
grill
heating
element
GH1
sends out heat to grill foods.
BOTTOM
HEATING
ELEMENT
GH2
The
bottom
heating
element
GH2
is
located
on
the
floor
of
the
oven
cavity
assembly.
The
bottom
heating
element
GH2
sends
out
heat
to
grill
foods.
TROUBLESHOOTING
GUIDE
When
troubleshooting
the
microwave
oven,
it
is
helpful
to
follow
the
Sequence
of
Operation
in
performing
the
checks.
Many
of
the
possible
causes
of
trouble
will
require
that
a
specific
test
be
performed.
These
tests
are
given
a
proce-
dure
letter
which
will
be
found
in
the
“Test
Procedure”
section.
IMPORTANT: If the oven becomes inoperative because
of a blown fuse F1 (Ti60mA) in the pri-
mary latch switch ~ monitor switch - moni-
tor resistor circuit, check the primary latch
switch, monitor switch and monitor resis-
tor (mounted on noise filter) before replac-
ing the fuse Fi (T160mA).
ity