R -8580
SERVICING
1. Precautions for Handing Electronic
Components
This unit uses PMOS LSl in the integral part of the
circuits. When handing 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.
:;
2)
,
order to protect PMOS LSI.
When storing and transporting, thoroughly
wrap them in aluminum foil.
Also wrap PW boards containing them in
aluminium foil.
When soldering, ground the technician as
shown in the figure
and use grounded
soldering iron and work table.
. .
appror.lMSl
k
/
2. Shapes of Electronic Components
AT
Transistor Transistor Transistor
2SB793
2SA937 DTA143ES
1
16 (R112)
DTD143A DTA114YS
Resistor Block.
DTC114ES
R50, R90, R 110
R112
3. Servicing 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 of from an external power
source.
(I ) 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 replace the
leads to 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.
For those models, therefore, check and repair
all the controls (with the sensor-related ones
included) of the touch control panel while
keeping it in contact with the oven proper.
B. 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 door
sensing switch (on PWB) of the touch control
panel with a jumper, which brings about an
operational 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 door sensing switch (on PWB) of the touch
control panel,which brings about an opera-
tional 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 panel by using the
dummy resistor(s).
4. Servicing Tools
Tools required when servicing the touch control
panel assembly.
1) Soldering iron: 30W
(To prevent leaking current, 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
1)
2)
3)
4)
5)
Before turning on the power source of the
control unit, remove the aluminum foil applied
for preventing static electricity.
Connect the connectors of the indicator and
key units to the control unit taking care that the
lead wires are not twisted.
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.
Attach connectors, electrolytic capacitors, etc.
to PWB, taking care that all connections are
tight.
Be sure to use specified components where
high precision is required.
(RD94ZAZU)
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