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R-9ZOO
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, an.d wedged
open.
3)
Discharge
high voltage capacitor.
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-
i
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 3D 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
4R
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
3IJ
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 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 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 up-
per latch switch
- lower latch switch
-
monitor
switch
- monitor
resistor
cir-
cuit,
check
the
upper
latch
switch,
lower latch switch,
monitor
switch
and
monitor
resistor
before
replacing
the
fuse M8A.
5
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