Sharp R-771(W)N - Page 20

TEST
PROCEDURES
(CONT'D)
I
ce
ae
Ee
PROCEDURE
LETTER
ae
O
RELAY
TEST
CARRY
OUT
3D
CHECKS.
COMPONENT
TEST
.
6
Remove
the
outer
case
and
check
voltage
between
Pin
Nos.
1
and
3
of
the
4
pin
connector
(E)
on
the
control
unit
with
an
A.C.
voltmeter.
The
meter
should
indicate
230
volts,
if
not
check
oven
circuit.
Relay Test
Check
voltage
at
the
relay
coil
with
a
D.C.
voltmeter
during
the
microwave
cooking
operation.
convection
cooking
operation
or
grill
operation.
DC.
voltage
indicated
..........
Defective
relay.
DC.
voltage
not
indicated
....
Check
diode
which
is
connected
to
the
relay
coil.
If
diode
is
good,
contro!
unit
is
defective.
OPERATIONAL
VOLTAGE
CONNECTED
COMPONENTS
Approx.
18.0V
D.C.
-Oven
lamp
/
Turntable
motor
Approx.
18.0V
D.C.
High
voltage
transformer
Approx.
24.0V
D.C.
Grill
heating
element
(Top
grill)
|
]
Approx,
24.0V
D.C.
Bottom
heating
element
npprox
240V0..
|
_Fanmowr
=
| RELAY SYMBOL
CARRY
OUT
48
CHECKS.
P
PROCEDURES
TO
BE
TAKEN
WHEN
THE
FOIL
PATTERN
ON
THE
PRINTED
WIRING
BOARD
(PWB)
IS
OPEN.
To
protect
the
electronic
circuits,
this
model
is
provided
with
afine
foil
pattern
added
to
the
input
circuit
®
onthe
PWB,
this
foil
pattern
acts
as
a
fuse.
Ifthe
foil
pattern
is
open,
follow
the
troubleshooting
guide
given
below
for
repair.
Problem:
POWER
ON,
indicator
does
not
fight
up.
CARRY
OUT
3D
CHECKS.
STEPS[___
OCCURANCE
GRUSE
OR
CORRECTION
6
rated
AC
voltage
Is
not
present
at
eck
supply
voltage
and
oven
power
cord.
Power
terminal
of
CPU
connector
(CN-A).
@
fated
AC
voltage
Is
present
at
primary
Ow
vollage
transformer
or
secondary
circuit
detective.
re
side
of
low
voltage
transformer.
Check
and
repair.
Only
pattern
at
"a"
Is
broken.
hsert
jumper
wire
Ji
and
solder.
|
|
(CARRY
OUT
3D
CHECKS
BEFORE
REPAIR)
d
Patiemn
at
a”
and
b"
are
broken.
nsert
the
coil
A
OUSYAZz
between
“c"
and
“a
(CARRY
OUT
3D
CHECKS
BEFORE
REPAIR)
NOTE:
*At
the
time
of
these
repairs,
make
a
lee
rs
om
visual
inspection
ofthe
varistor
for
burn-
Res
ix
ing
damage
and
examine
the
trans-
former
with
tester
for
the
presence
of
layer
short
circuit
(check
primary
coil
resistance).
if
any
abnormal
condition
is
detected,
replace
the
defective
parts.
CARRY
OUT
4R
CHECKS.
R-771 - 20