SOI 03.06 FV
27/38
599 36 78-45
SERVICING
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. Servicing of Touch Control Panel
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 available either from the
power line of the oven itself or from an external
power
source.
(1) Servicing the touch control panel with
power line of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF
THE MICROWAVE OVEN IS STILL LIVE
DURING SERVICING AND PRESENTS A
HAZARD.
Therefore, before checking the performance of
the touch control panel,
1) Disconnect the power supply cord, and then
remove outer case.
2) Open the door and block it open.
3) Discharge high voltage capacitor.
4) Disconnect the leads to the primary of the
power
transformer.
5) Ensure that these leads remain isolated from
other components and oven chassis by using
insulation
tape.
6) After that procedure, re-connect the power
supply
cord.
After checking the performance of the touch
control panel,
1) Disconnect the power supply cord.
2) Open the door and block it open.
3) Re-connect the leads to the primary of the
power
transformer.
4) Re-install the outer case (cabinet).
5) Re-connect the power supply cord after the
outer case is installed.
6) Run the oven and check all functions.
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 is
long enough that they may be separated from
each other. For those models, it is possible to
check and repair the controls of the touch
control panel while keeping it apart from the
oven; in this case you must short both ends of
the door sensing switch (on PWB) of the touch
control panel with a jumper, which activates an
operational state that is equivalent to the oven
door being closed.
(2) Servicing the touch control panel with
power supply from an external power
source:
Disconnect the touch control panel completely
from the oven, and short both ends of the door
sensing switch (SW3: STOP SWITC on PWB
CNB connector 1 and 2) of the touch control
panel, which activates 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.
3. Servicing Tools
Tools required to service the touch control panel
assembly.
1) Soldering iron: 30W
(It is recommended to use a soldering iron with
a grounding terminal.)
2) Others: Hand tools
4. 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 key unit to the
control unit being sure that the lead wires are
not
twisted.
3) After aluminium foil is removed, be careful 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, making sure that all connections are
tight.
5) Be sure to use specified components where
high precision is required.
approx. 1 M ohm
