Sharp R-2397 service manual Test Procedures Contd, Component Test, Letter, Relay Test

R-2397

	TEST PROCEDURES (CONT'D)
PROCEDURE	COMPONENT TEST
LETTER
	If a specific pad does not respond, the above method may be used (after clearing the control unit)
	to determine if the control unit or key pad is at fault.
P	RELAY TEST
	CARRY OUT 3D CHECKS.
	Remove the outer case and check voltage between Pin Nos. 5 and 7 of the connector (A) on the
	control unit with an A.C. voltmeter. The meter should indicate 230 volts, if not check control unit
	circuity.

RY1, RY3 and RY4 Relay Test

These relays are operated by D.C. voltage.

Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.

DC. voltage indicated		Defective relay.
DC. voltage not indicated		Check diode which is connected to the relay coil. If
		diode is good, control unit is defective.
RELAY SYMBOL	OPERATIONAL VOLTAGE		CONNECTED COMPONENTS
RY1	APPROX. 19.0V D.C.		Oven lamp, Blower motor and Stirrer motor
RY3	APPROX. 16.0V D.C.		Power transformer 1
RY4	APPROX. 18.0V D.C.		Power transformer 2

CARRY OUT 4R CHECKS.

QPROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD (PWB) IS OPEN

To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given below for repair.

Problem: POWER ON, indicator does not light up.

CARRY OUT 3D CHECKS.

STEPS	OCCURANCE	CAUSE OR CORRECTION
1	The rated AC voltage is not present at	Check supply voltage and oven power cord.
	POWER terminal of CPU connector (CN-A).
2	The rated AC voltage is present at primary	Low voltage transformer or secondary circuit defective.
	side of low voltage transformer.	Check and repair.
3	Only pattern at "a" is broken.	*Insert jumper wire J24 and solder.
		(CARRY OUT 3D CHECKS BEFORE REPAIR)
4	Pattern at "a" and "b" are broken.	*Insert the coil RCILF2003YAZZ between "c" and "d".
		(CARRY OUT 3D CHECKS BEFORE REPAIR)

NOTE: *At the time of these repairs, make a visual inspection of the varistor for burning damage and examine the transformer with tester for the presence of layer short-circuit (check primary coil resistance). If any abnormal condition is detected, replace the defective parts.

CARRY OUT 4R CHECKS.

			d		(J29)
			(J24)	VRS1
	RY1	a			(VRS2)
			b
3(1)	5(3)	(J23)	c	9(7)	(9)

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