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(4) Ensure that these leads remain isolated from other
components and oven chassis by using insulation tape.
After that procedure, re -connect the power supply cord.
(1) After checking the performance of the touch control
panel,
(2) Disconnect the power supply cord.
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).
Re -connect the power supply cord after the outer case
is installed.
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 proper is so 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, checking them is
possible if the 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).
3. Servicing Tools
Tools required to service the touch control panel assembly.
1) Soldering iron: 60W
(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
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 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 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
.
PRECAUTIONS FOR USING LEAD-FREE SOLDER
1. Employing lead-free solder
The "Main PWB" of this model employs lead-free solder. This is indicated by the "LF" symbol printed on the PWB and in the service
manual. The suffix letter indicates the alloy type of the solder.
Example:
Indicates lead-free solder of tin, silver and copper
2. Using lead-free wire solder
When repairing a PWB with the "LF" symbol, only lead-free solder should be used. (Using normal tin/lead alloy solder may result in
cold soldered joints and damage to printed patterns.)
As the melting point of lead -free solder is approximately 40ºC higher than tin/lead alloy solder, it is recommend that a dedicated bit is
used, and that the iron temperature is adjusted accordingly.
3. Soldering
As the melting point of lead-free solder (Sn-Ag-Cu) is higher and has poorer wettability, (flow), to prevent damage to the land of the
PWB, extreme care should be taken not to leave the bit in contact with the PWB for an extended period of time. Remove the bit as
soon as a good flow is achieved. The high content of tin in lead free solder will cause premature corrosion of the bit. To reduce wear
on the bit, reduce the temperature or turn off the iron when it is not required.
Leaving different types of solder on the bit will cause contamination of the different alloys, which will alter their characteristics, making
good soldering more difficult. It will be necessary to clean and replace bits more often when using lead-free solder. To reduce bit wear,
care should be taken to clean the bit thoroughly after each use.
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