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1.
Precautions for Handling Electronic Components:
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following precau-
tions should be strictly followed. CMOS LSI have ex-
tremely high impedance at its input and output terminals.
For this reason, it is easily infl uenced 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 fi gure and use grounded soldering iron and work
table.
NOTE: For Control Panel Removal See Page 4-8.
2.
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:
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:
a)
Disconnect the power supply cord, and then re-
move outer case.
b)
Open the door and block it open.
c)
Discharge high voltage capacitor. (Figure 4-1)
d)
Disconnect the leads to the primary of the power
transformer.
e)
Ensure that these leads remain isolated from
other components and oven chassis by using
insulation tape.
f)
After that procedure, re-connect the power supply
cord.
After checking the performance of the touch con-
trol panel:
a)
Disconnect the power supply cord.
b)
Open the door and block it open.
c)
Re-connect the leads to the primary of the power
transformer.
d)
Re-install the outer case (cabinet).
e)
Re-connect the power supply cord after the outer
case is installed.
f)
Run the oven and check all functions.
Drawer Microwave
TOUCH CONTROL PANEL SERVICING
4-5
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-re-
lated 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, 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 activates an operational 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
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 activates an operational state that is equiva-
lent 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 con-
trols of the touch control panel by using the dummy
resistor(s).
3. 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 grounding terminal.)
2)
Oscilloscope: Single beam, frequency range: DC-
4-50MHz type or more advanced model.
3)
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 specifi ed components where high
precision is required.
Access & Removal
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