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1.
2.
R-9380
SERVICING
Precautions
for
Handing
Electronic
Components
This unit uses PMOS LSI in the integral
part of the
circuits.
When handling
these parts, the following
precautions
should
be strictly
followed.
PMOS
LSI have extremely
high
impedance
at its
input
and output
terminals.
For this
reason,
it is
easily influenced
by the surrounding
high voltage
power
source, static electricity
charged
in clothes,
etc,and
sometimes
it is not fully
protected
by the
built-in
protection
circuit.
In order to protect
PMOS LSI.
1 ) When
storing
and
transporting,
thoroughly
wrap them in aluminum
foil.
Also
wrap
PW
boards
containing
them
in
aluminium
foil.
2)
When
soldering,
ground
the
technician
as
shown
in
the
figure
and
use
grounded
soldering
iron and work table.
.
appmx.
1 MR
h
/
m
Shapes
of Electronic
Components
Transistor
DTA143ES
Regurator
IC
IC2
AN79Ll2
8
ECB
Transisotr
DTCl14EA
1 : QUT Terminal
2 : COMMON
Terminal
Hybrid
!C
3 : IN Terminal
IC 3
3.
Servicina
of Touch
Control
Panel
We describe the procedures
to permit servicing
the
touch control
panel of the microwave
oven and the
cautions
you must consider
when doing so.
To carry the servicing,
power
supply
to the touch
control
panel is available
either from the power line
of the oven proper itself or from an external
power
source.
(1) Servicing
the
touch
control
panel
with
power
supply
from
the oven
proper:
CAUTION:
THE HIGH
VOLTAGE
TRANSFORMER
OF
THE
MICROWAVE
OVEN
IS STILL
ALIVE
TO
GIVE
YOU
DANGER
DURING
SER-
VICING.
Therefore,
when
checking
the performance
of
the touch
control
panel,put
the outer cabinet
on the oven proper to keep from touching
the
high voltage
transformer,
or unplug
the primary
terminal
(connector)
of the high voltage
trans-
former to turn it off; and the end of such con-
nector
shall
be insulated
with
an insulating
tape.
After
servicing,
be sure to repiace
the
leads ~0 their original
locations.
A.
On some models,
the power
supply
cord
be-
tween
the touch
control
panel
and the oven
proper
is so short that they can't be separated
from each other.
4.
Servicing
Tools
Tools
required
when
servicing
the touch
control
panei assembly.
1) Soldering
iron: 30W
(To prevent
leaking
cur-
rent, it is recommended
to use a soldering
iron with
a grounding
terminal.)
2)
Oscilloscope:
Single
beam, frequency
range:
DC - IOMHz
type
or more ad-
vanced model.
3)
Others:
Hand tools
5.
Other
Precautions
For those
models,
therefore,
check
and repalr
all the controls
(with
the sensor-related
ones
included)
of the
touch
control
panel
while
keeping
it in contact
with the oven proper.
6.
On some models, on the other hand, the power
supply
cord between
the touch
control
panel
and the oven proper
is so long that they may
be separated
from each other.
For those mod-
els, therefore,
it is allowed
to check and repair
the controls
of the touch
control
panel while
keeping
it apart from the oven
proper;in
this
case you
must
short
both
ends
of the stop
switch
(on PWB)
of the touch
control
panel
with
a Jumper, which
brings
about
an opera-
tional
state that is equivalent
to that with
the
oven door being closed.
As to the sensor-related
controls
of the touch
control
panel, their checking
is allowed
if the
dummy
resistor(s)
whose
resistance
is equal to
that of those controls
is used.
(2) Servicing
the
touch
control
panel
with
power
supply
from
an
external
power
source:
Disconnect
the touch
control
panel completely
from the oven proper,and
short
both
ends of
the stop switch
(on PWB) of the touch control
panel,which
brings
about
an operational
state
that
is equivalent
with
the oven
door
being
closed.
And connect
an external
power source
to the power input terminal
of the touch control
panel, and then it is allowed
to check and repair
the controls
of the touch control
panel;as in the
case of (1 )-B above, it is here also possible
to
check the sensor-related
controls
of the touch
control
panei by using the dummy
resistor(s).
1)
Before
turning
on the
power
source
of the
control
unit, remove the aluminum
foil applied
for preventing
static electricity.
2)
Connect
the connectors
of the indicator
and
key units to the control
unit taking care that the
lead wires are not twisted.
3)
After aluminum
foil is removed,
take extra care
that abnormal
voltage
due to static
electricity
etc. is not applied
to the input or output
termi-
nals.
4)
Attach
connectors,
eiectrolytic
capacitors,
etc.
to PWB, taking
care that all connections
are
tight.
5)
Be sure to use speclfled
components
wnere
high precision
is required.
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