Sharp MMD24B, MMD24S manual Test Procedures, Component Test, Letter, B Key Unit Test, C Relay Test

MMD24S
MMD24B	TEST PROCEDURES
PROCEDURE	COMPONENT TEST
LETTER

4)Reconnect all leads removed from components during testing.

5)Re-install the covers.

6)Reconnect the power supply cord after the covers are installed.

7)Run the oven and check all functions.

BKEY UNIT TEST

1.Disconnect the power supply cord, and then remove outer case.

2.Open the drawer and block it open.

3.Discharge high voltage capacitor.

4.If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable is making good contact, verify that the door sensing switch (stop switch) operates properly; that is the contacts are closed when the drawer is closed and open when the drawer is open. If the door sensing switch (stop switch) is good, disconnect the flat ribbon cable that connects the key unit to the control unit and make sure the drawer sensing switch is closed (either close the drawer or short the door sensing switch connecter). Use the Key unit matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and must be replaced. If the control unit does not respond, it is faulty and must be replaced. 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.

5.Reconnect all leads removed from components during testing.

6.Re-install the outer case (cabinet).

7.Reconnect the power supply cord after the outer case is installed.

8.Run the oven and check all functions.

CRELAY TEST

	6	9
	1	8
	2	3
	7	4
	SENSOR	OPEN
	COOK
	SENSOR	SENSOR
	REHEAT	POPCORN
REHEAT	DEFROST	MICRO
		WARM
STOP/	START/
	EASY
CLEAR
	MINUTE

TIMER

CLOCK

0 5

POWER LEVEL

SET UP/ HELP

CONTROL LOCK ON/OFF

CLOSE

1.Disconnect the power supply cord, and then remove outer case.

2.Open the door and block it open.

3.Discharge high voltage capacitor.

4.Disconnect the leads to the primary of the power transformer.

5.Ensure that these leads remain isolated from other components and oven chassis by using insulation tape.

6.After that procedure, re-connect the power supply cord.

7.Remove the outer case and check voltage between Pin Nos. 5 and 7 of the 4 pin connector (CN-A) on the power unit with an A.C. voltmeter.

The meter should indicate 120 volts, if not check oven circuit. RY1, RY2, 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. 26V D.C.	Oven lamp / Common
RY2		Approx. 25V D.C.	Power transformer
RY3		Approx. 26V D.C.	Stirrer motor
RY4		Approx. 26V D.C.	Fan motor
RY5		Approx. 26V D.C.	Switching regurator for drawer motor

8.Disconnect the power supply cord, and then remove outer case.

9.Open the door and block it open. 10.Discharge high voltage capacitor.

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