Servicing, Shapes of Electronic Components

R-8580

SERVICING

1. Precautions for Handing Electronic Components

This unit uses PMOS LSl in the integral part of the circuits. When handing these parts, the following precautions should be strictly followed.

PMOS 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 charged in clothes, etc,and sometimes it is not fully protected by the built-in protection circuit.

,order to protect PMOS LSI.

:; When storing and transporting, thoroughly wrap them in aluminum 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.

k appror.lMSl

2.Shapes of Electronic Components

Transistor	Transistor	Transistor	1	16 (R112)
2SB793	2SA937	DTA143ES	Resistor	Block.
	DTD143A	DTA114YS	R50, R90, R 110

DTC114ES	R112

3.Servicing of Touch Control Panel

We describe the procedures to permit servicing the touch control panel of the microwave oven and the cautions you must consider when doing so.

To carry the servicing, power supply to the touch control panel is available either from the power line of the oven proper itself of from an external power source.

(I ) Servicing the touch control panel with power supply from the oven proper:

CAUTION:

THE HIGH VOLTAGE TRANSFORMER OF

THE MICROWAVE OVEN IS STILL ALIVE

TO GIVE YOU DANGER DURING SER- VICING.

Therefore, when checking the performance of the touch control panel,put the outer cabinet on the oven proper to keep from touching the high voltage transformer, or unplug the primary terminal (connector) of the high voltage trans- former to turn it off; and the end of such con- nector shall 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 be- tween the touch control panel and the oven proper is so short that they can’t be separated from each other.

For those models, therefore, check and repair all the controls (with the sensor-related ones included) of the touch control panel while keeping it in contact with the oven proper.

B.On some models, on the other hand, the power supply cord between the touch control panel and the oven proper is so long that they may be separated from each other. For those mod- els, therefore, it is allowed 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 that with the oven door being closed.

As to the sensor-related controls of the touch control panel, their checking is allowed if the dummy resistor(s) whose resistance is equal to

that of those controls is 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 opera- tional state that is equivalent with the oven door being closed. And connect an external power source to the power input terminal of the touch control panel, and then it is allowed to check and repair the controls of the touch control panel;as in the case of (1 )-B above, it is here also possible to check the sensor-related controls of the touch control panel by using the dummy resistor(s).

4. Servicing Tools

Tools required when servicing the touch control panel assembly.

1)Soldering iron: 30W

(To prevent leaking current, it is recommended to use a soldering iron with a grounding terminal.)

2)	Oscilloscope:	Single	beam, frequency range:
		DC - IOMHz type or more ad-
		vanced	model.
3)	Others:	Hand	tools

5. Other Precautions

1)Before turning on the power source of the control unit, remove the aluminum foil applied

for preventing static electricity.

2)Connect the connectors of the indicator and key units to the control unit taking care that the lead wires are not twisted.

3)After aluminum foil is removed, take extra care that abnormal voltage due to static electricity etc. is not applied to the input or output termi- nals.

4)Attach connectors, electrolytic capacitors, etc. to PWB, taking care that all connections are tight.

5)Be sure to use specified components where high precision is required.

(RD94ZAZU)