Sharp R-771(W)N - Page 16

ot Henan dene renee
+EST
PROCEDURES
(CONT'D)
COMPONENT
TEST
PROCEDURE
LETTER
CARRY
OUT
4R
CHECKS.
|
@
NOTE:
FOR
MEASUREMENT
OF
THE
RESISTANCE
OF
THE
RECTIFIER,
THE
BATTERIES
OF
THE
MEASURING
INSTRUMENT
MUST
HAVE
A
VOLTAGE
AT
LEAST
&
VOLTS,
BE-
&
CAUSE
OTHERWISE
AN
INFINITE
RESISTANCE
MIGHT
BE
SHOWN
IN
BOTH
DIREC-
TIONS.
D
WIGH
VOLTAGE
CAPACITOR
TEST
CARRY
OUT
3D.
CHECKS.
A.
\solate
the
high
voltage
capacitor
from
the
circuit.
B.
Continuity
check
must
be
carried
out
with
measuring
instrument
which
is
set
to
the
highest
resistance
range.
C.
Anormal
capacitor
shows
continuity
for
a
short
time
(kick)
and
ihen
a
resistance
of
about
10M
after
it
has
been
charged.
D.
A
short-circuited
capacitor
shows
continuity
all
the
time.
E.
An
open
capacitor
constantly
shows
&
resistance
about
10
MQ
because
of
its
internal
10M&2
resistance.
=.
When
the
internal
wire
is
opened
in
the
high
voltage
capacitor
shows
an
infinite
resistance.
G.
The
resistance
across
all
the
terminals
and
the
chassis
must
be
infinite
when
the
capacitor
is
normal.
lf
incorrect
reading
are
obtained,
the
high
voltage
capacitor
must
be
replaced.
CARRY
OUT
48
CHECKS.
E
SWITCH
TEST
CARRY
OUT
3D
CHECKS.
.
isolate
the
switch
to
be
tested
and
using
an
ohmmeter
check
between
the
terminals
as
described
in
the
following
table.
Table:
Terminal
Connection
of
Switch
@
COM;
Common
terminal,
Released
—Spen
creuit
|
__Shorterouit__|
NO;
Normally
open
terminal
Depressed
her
crout
|
__Openccrouft__|
NC;
Normally
close
terminal
\f
incorrect
readings
are
obtained,
make
the
necessary
switch
adjustment
or
replace
the
switch.
CARRY
OUT
48
CHECKS.
F
THERMAL
CUT-OUT
TEST
CARRY
OUT
3D
CHECKS.
©
Disconnectthe
leads
from
the
terminals
of
the
thermal
cut-out.
Then
using
an
ohmmeter,
make
a
continuity
test
across
the
two
terminals
as
described
in
the
below.
Table:
Thermal
Cut-out
Test
Temperature
of
"ON"
condition
(closed
circuit).
|
condition
(open
circuit).
°C)
CC)
Thermal
cut-out
125°C
Above
125°C
if
incorrect
readings
are
obtained,
replace
the
thermal
cut-out.
Indication
of
ohmmeter
(Whenroom
temperature
is
approx.
20°C.)
.
Parts
Name
Closed
circuit
Closed
circuit
An
open
circuit
thermal
cut-out
C1
(MG)
indicates
that
the
magnetron
has
overheated,
this
may
be
due
to
resistricted
ventilation,
cooling
fan
failure
or
a
fault
condition
within
the
magneiron
or
HV.
circuit.
An
open
circuit
thermal
cut-out
TG2
(OVEN)
indicates
that
the
food
in
the
oven
cavity
may
catch
fire,
this
may
be
due
to
over
heating
produced
by
improper
setting
of
the
cooking
timer
or
failure
of
the
@:
control
panel.
4
CARRY
OUT
4R
CHECKS.
@
R-771
-
16
a ens
A Tt P
= recat ee keep tte ee