R-7N76(W)M
R-7N76(B)M
27
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following
precautions should be strictly followed. CMOS 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
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.
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 models, 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
operational state that is equivalent to the 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 are 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 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-10MHz
type or more advanced model.
3) Others: Hand tools
5. Other Precautions
1) Before turning on the power source of the control unit,
remove the aluminium foil applied for preventing static
electricity.
2) Connect the connectors of the indicator and key unit to
the control unit taking care that the lead wires are not
twisted.
3) After aluminium foil is removed, take extra care that
abnormal voltage due to static electricity etc. is not
applied to the input or output terminals.
4) Attach connectors, electrolytic capacitors, etc. to PWB,
taking care that all connections are tight.
5) Be sure to use specified components where high precision
is required.
SERVICING
2) When soldering, ground the technician as shown in the
figure and use grounded soldering iron and work table.
approx. 1M ohm
2. Shapes of Electronic Components
E
C B
E
C
B
Transistor
DTA143ES
DTB143ES
DTD143ES
Transistor
2SB910M
3. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the touch
control panel of the microwave oven and the cautions you
must considre 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.
(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 SERVICING.
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
transformer to turn it off; and the end of such connector 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 between the touch
control panel and the oven proper is so short that they can’t
