Panasonic NN-8508 - Page 15

NN-8508, NN-8558
NN-8808, NN-8858
NN-8808P
CAUTIONS TO BE OBSERVED WHEN TROUBLESHOOTING
Unlike
many
other
appliances,
the
microwave
oven
is
high-voltage,
high-current
equipment.
Though
it
is
free
from
danger
in
ordinary
use,
.
extreme
care
should
be
taken
during
repair.
CAUTION
Servicemen
should
remove
their
watches
whenever
working
close
to
or
replacing
the
magnetron.
1. Check the grounding
Do
not
operate
on
a
2-wire
extension
cord.
The
microwave
oven
is
designed
to
be
used
when
grounded.
It
is
imperative,
therefore,
to
make
sure
it
is
grounded
properly
before
beginning
repair
work.
2.
Warning
about
the
electric
charge
in
the
high
voltage
capacitor
(Fig.
15)
For
about
30
seconds
after
the
oven
is
turned
off,
an
electric
charge
remains
in
the
high
voltage
capacitor.
When
replacing
or
checking
parts,
remove
the
power
plug
from
the
outlet
and
short
the
terminal
of
the
high
voltage
capacitor
(terminal
of
lead
wire
from
diode)
to
chassis
ground
with
an
insulated
handle
screwdriver
to
discharge.
WARNING
There
is
high-voltage
present,
with
high-current
capa-
bilities
in
the
circuits
of
the
high
voltage
winding
and
filament
winding
of
the
high
voltage
transformer.
It
is
extremely
dangerous
to
work
on
or
near
these
circuits
with
oven
energized.
DO
NOT
measure
the
voltage
in
the
high
voltage
circuit
including
filament
voltage
of
magnetron.
WARNING
Never
touch
any
circuit
wiring
with
your
hand
nor
with
an
insulated
too!
during
operation.
3.
When
parts
must
be
replaced,
remove
the
power
plug
from
the
outlet.
4.
When
the
15
Amp
fuse
is
blown
due
to
the
operation
of
short
switch:
WARNING
When
the
15
Amp.
fuse
is
blown
due
to
the
operation
of
short
switch,
you
must
replace
latch
switch
A
and
short
switch.
For
U.S.A.
models,
also
replace
power
relay
B
when
the
continuity
check
reads
shorted
contacts (1-2).
(A)
This
is
mandatory.
Refer
to
page
23
for
the
necessary adjustments
for
these switches.
(B)
When
replacing
the
fuse,
confirm
that
it
has
the
appropriate
rating
for
these models.
(C)
When
replacing
faulty
switches,
be
sure
mounting
tabs
are
not
bent,
broken
or
otherwise
deficient
in
their
ability
to
hold
the
switches.
5.
Avoid
inserting
nails,
wire,
etc.
through
any
holes
in
the
unit
during
operation.
Never insert a wire, nail or any other metal object through the lamp
holes on the cavity or any other holes or gaps, because such objects
may
work
as
an
antenna
and
cause
microwave
leakage.
15A
FUSE
HIGH
VOLTAGE
CAPACI TOR
Touch chassis side first then short to the high voltage capacitor
terminal.
6. Confirm after repair Bes?
(A) After repair or replacement of parts, make sure that the screws of the
oven, etc. are neither loose nor missing.
Microwaves might leak if screws are not properly tightened.
(B) Make sure that all electrical connections are tight before inserting the
plug into the wall outlet.
(C) Check for microwave energy leakage. (Refer to procedure for
measuring microwave energy leakage on page 24.)