SHARP R-343(W)M
Manual de Servicio

TOUCH CONTROL PANEL ASSEMBLY
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 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.
approx. 1M ohm

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). 4. 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) Oscilloscope: Single beam, frequency range: DC 10MHz type or more advanced model. 3) Others: Hand tools

2. Shapes of Electronic Components

CB E

Transistor 2SA1267Y KRA101M KRC101M KRC105M

3. 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 5. Other Precautions from an external power source. 1) Before turning on the power source of the control unit, remove the aluminium foil applied for preventing (1) Servicing the touch control panel with power static electricity. supply of the oven : 2) Connect the connector of the key unit to the control CAUTION: unit being sure that the lead wires are not twisted. THE HIGH VOLTAGE TRANSFORMER OF THE 3) After aluminium foil is removed, be careful that MICROWAVE OVEN IS STILL LIVE DURING SERVabnormal voltage due to static electricity etc. is not ICING AND PRESENTS A HAZARD . applied to the input or output terminals. 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 transformer to turn it off; the end of such connector must 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 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. R343M - 11 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.