24
R-22GV
R-22GT
R-23GT
R-24GT
SERVICING
3. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the pre-
cautions you must take when doing so. To perform the
servicing, power to the touch control panel is available
either from the power line of the oven itself or from an
external power source.
(1) Servicing the touch control panel with power supply
of the oven:
CAUTION:
THE HIGH VOLTAGE TRANS-
FORMER OF THE MICROWAVE OVEN IS
STILL LIVE DURING SERVICING
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
primary terminal (connector) of the high voltage trans-
former to turn it off; the end of such connector must be
approx. 1M ohm
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 itself is so short that the two
can’t be separated. For those models, check and repair 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 operational state that is
equivalent to the oven door being closed. As for the
sensor-related controls of the touch control panel, check-
ing 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 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 operational state that is equivalent 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-related
controls of the touch control panel by using the dummy
resistor(s).
4. Servicing Tools
Tools required to service the touch control panel assem-
bly.
1) Soldering iron: 30W
(It is recommended to use a soldering iron with a ground-
ing 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) After aluminium foil is removed, be careful that abnormal
voltage due to static electricity etc. is not applied to the
input or output terminals.
3) Attach connectors, electrolytic capacitors, etc. to PWB,
making sure that all connections are tight.
4) Be sure to use specified components where high precision
is required.
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.
2) When soldering, ground the technician as shown in the
figure and use grounded soldering iron and work table.
2. Shapes of Electronic Components
E
C B
IC
KIA7805P1
3
2
1
Transistor
DTA123ES
DTB143ES
DTD143ES
KRA101M
KRC101M
