Sharp Carousel II R-3A54 Service Manual - Page 9

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R-3A54
R-3E54
SERVICING
WARNING
TO SERVICE
PERSONNEL
Microwave
ovens contain
circuitry
capable of producing
very high voltage and current, contact
with any part
of the high voltage
circuit
will result in electrocuition.
REMEMBER
TO CHECK
3D
1)
Disconnect
the supply.
2)
Door opened, and wedged
open.
3)
Discharge
high voltage
capacitor.
I-
WARNING
AGAINST
THE CHARGE
OF THE
HIGH-VOLTAGE
CAPACITOR
The high-voltage
capacitor
remains
charged
about
60 seconds
after the oven
has been
switched
off. Wait for 60 seconds
and then
short-circuit
the
connection
of
the
high-voltage
capacitor
(that
is, of the con-
necting
lead
of the
high-voltage
rectifier)
against
the chassis with
the use of an insu-
lated screwdriver.
Sharp
recommend
that
wherever
possible
fault-finding
is carried out with
the supply
discon-
nected.
It may
in, some
cases,
be necessary
to
connect
the supply
after the outer
case has been
removed, in this event carry out 3lJ checks and then
disconnect
the leads to the primary
of the power
transformer.
Ensure that these leads remain isolated
from other components
and the oven chassis.
(Use
insulation
tape if necessary.)
When
the testing
is
completed
carry out 3D checks
and reconnect
the
leads to the primary of the power transformer.
REMEMBER
TO CHECK
$lJ
1)
Reconnect
all leads removed from components
during
testing.
2)
Replace the outer case (cabinet).
3)
Reconnect
the supply.
4)
Run the oven. Check all functions.
Microwave
ovens should
not be run empty. To test
for the
presence
of microwave
energy
within
a
cavity,
place
a cup
of cold
water
on the
oven
turntable,
close
the door
and set the microwave
timer for two
(2) minutes.
Set the power
level to
HIGH and push the START button.
When the two
minutes
has elapsed
(timer at zero) carefully
check
that the water is now hot. If the water remains cold
carry
out
3lJ
checks
and
re-examine
the
con-
nections
to the component
being tested.
When all service work is completed,
and the oven is fully
assembled,
the microwave
power output
should
be checked and a microwave
leakage test carried out.
TROUBLESHOOTING
GUIDE
When
troubleshooting
the
microwave
oven,
it
is
helpfull
to follow
the Sequence
of Operation
in per-
forming
the checks.
Many
of the possible
causes of
trouble
will
require
that a specific
test be performed.
These tests are given a procedure
letter which
will
be
found
in the "Test Procedure"section.
IMPORTANT:
If the oven
becomes
inoperative
be-
cause of a blown
fuse
(M8A)
in the
1 st latch switch
-
2nd latch switch
-
monitor
switch
-
monitor
resisitor cir-
cu-it, check
the 1st latch
switch,
2nd
latch
switch,
monitor
switch
and
monitor
resistor
before
replacing
the
fuse (M8A).