Sharp R-24AT Memory IC, Servicing, Figure T-2. Relation between Pin Nos, and Signals, Description

R-22AT

R-24AT

2-2 Memory IC (I-2)

CAT24WC16PI is a 4K-bit, serial memory, enabling CMOS to be erased/written electrically. This memory is constructed with 512 registers x 8bits, enabling individual access, read and write operations to be performed. Details of input/output signal for IC2 are as shown in the following diagram.

		TOP VIEW
A0	1	8	VCC
A1	2	7	TEST
A2	3	6	SCL
VSS	4	5	SDA

FUNCTIONAL DIAGRAM

(3) Vcc
(4) Vss			START CYCLE	H.V. GENERATION
				TIMING
				& CONTROL
(5) SDA	START
	STOP
	LOGIC
		CONTROL
		LOGIC		E 2PROM
			64
	SLAVE ADDRESS			512 x 8
			XDEC
(6) SCL	REGISTER
	COMPARATOR
	LOAD	INC
	WORD
	ADDRESS		1	64
	COUNTER		5
	R/W		3	YDEC
			CK	8
		PIN			Dout
				DATA REGISTER
	Dout
	ACK

Figure T-2. Relation between Pin Nos, and Signals

Pin No.	Signal	I/O	Description
1-3	A0-A2	IN	Connected to GND.
4	VSS	IN	Connected to VC(-5V).
5	SDA	IN/OUT	Serial data input/output : input/outputs data to I-1.
6	SCL	IN	Clock signal input : input/outputs serial data at every one pulse.
7	TEST	IN	Connected to VC(-5V).
8	VCC	IN	Connected to GND.

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 pre- cautions 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 electric- ity 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.

approx. 1M ohm

2. Shapes of Electronic Components

				Transistor
2 3	B			KIA79L05P
				DTB143ES
	C
1	E		B	DTD143ES
Transistor	Transistor	E C		KRA101M
2SB953	2SB1238

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 from an external power source.

(1)Servicing the touch control panel with power supply of the oven:

CAUTION: THE HIGH VOLTAGE TRANSFORMER OF THE MICROWAVE OVEN IS STILL LIVE DURING SERVICING PRESENTS A HAZARD.

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 in- cluded) 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, 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

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