+3A55
1 .Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following pre-
cautions should be strictly followed. CMOS LSI have ex-
tremely high impedance at its input and output terminals.
For this reason, it is easily influenced by the surrounding
high voltage power source, static electricity charge in
clothes, etc, and sometimes it is not fully protected by the
built-in protection circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap them
in aluminium foil. Also wrap all 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.
2.Shapes of Electronic Components
d&2 /
approx 1 M ohm
3.Servicing of Touch Control Panel
Transistor
D-I-Al 14ES
DTBl43ES
DTDi 43ES
2SA933S
We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the
precautions you must take when doing so. To perform
the servicing, power to the touch control panel is avail-
able either from the power line of the oven itself or from
an external power source.
(1)Servicing the touch control panel with power sup-
ply of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE MI-
CROWAVE OVEN IS STILL LIVE DURING SERVIC-
ING PRESENTS A HAZARD.
Therefore, when checking the performance of the touch
control panel, put the outer cabinet on the oven to avoid
touching the high voltage transformer, or unplug the pri-
mary terminal (connector) of the high voltage trans-
former to turn it off; the end of such connector must 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 between the
SERVICING
touch control panel and the oven itself is so short that the
two can’t be separated. For those models, check and re-
pair all the controls (sensor-related ones included) of the
touch control panel while keeping it connected to the
oven.
B. On some models, the power supply cord between the
touch control panel and the oven proper is long enough
that they may be separated from each other. For those
models, therefore, it is possible 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 op-
erational state that is equivalent to the oven door being
closed. As for the sensor-related controls of the touch
control panel, checking them is possible if dummy
resistor(s) with resistance equal to that of the controls
are used.
(2)Servicing the touch control panel with power sup-
ply from an external power source:
Disconnect the touch control panel completely from the
oven properand short both ends of the door sensing
switch (on PWB) of the touch control panel,which brings
about an operational state that isequivalent to the oven
door being closed. Connect an external power source to
the power input terminal of the touch control panel, then
it is possible to check and repair the controls of the touch
control panel it is also possible to check the sensor-re-
lated controls of the touch control panel by using the
dummy resistor(s).
4.Servicing Tools
Tools required to service the touch control panel assem-
biv.
I j’ Soldering iron: 30W
ilt is recommended to use a soidering iron with a
grounding terminai.)
2) Oscilloscope: Single beam. frequency range: DC-
1 OMHz type or more advanced model.
3; Others: Hand tools
5.0ther Precautions
1) i3efore turning on the power source of the control unit,
remove the aluminium foil applied for preventing
static electricity.
2) Connect the connector of the key unit to the control
unit being sure that the lead wires are not twisted.
3) After aluminium foil is removed, be careful that abnor-
mal voltage due to static electricity etc. is not applied
to the input or output terminals.
4) Attach connectors, electrolytic capacitors, etc. to
PWB. making sure that all connections are tight.
5) Be. sure to use specified components where high pre-
cision is required.
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