M: Relay Test; N: Procedures To Be Taken When The Foil Pattern On The Printed Wiring Board (Pwb) Is Open; O: Ah Sensor Test - Sharp R-380LS Service Manual

Microwave oven

Table of Contents

[13] M: RELAY TEST

CARRY OUT 3D CHECKS.

Remove the outer case and check voltage between the cabinet side terminal of the relay RY1 and the lower side terminal of the relay RY2 on the

power unit with an A.C. voltmeter. The meter should indicate 230 - 240 volts, if not check oven circuit.

RY1 and RY2 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

RY1

RY2

CARRY OUT 4R CHECKS.

[14] N: PROCEDURES 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.

CARRY OUT 3D CHECKS.

STEPS

The rated AC voltage is not present between the cabinet side terminal of the

relay RY1and the lower side terminal of the relay RY2.

The rated AC voltage is present to primary side of low voltage transformer.

Only pattern at "a" is broken.

Pattern at "a" and "b" are broken.

NOTE: *At the time of making these repairs, make a visual inspection of the varistor.

Check for burned damage and examine the transformer with a tester for the

presence of layer short-circuit (check the primary coil resistance). If any abnor-

mal condition is detected, replace the control unit.

CARRY OUT 4R CHECKS.

[15] O: AH SENSOR TEST

Checking the initial sensor cooking condition

WARNING: The oven should be fully assembled before following procedure.

1) The oven should be plugged in at least two minutes before sensor cooking.

2) Room temperature should not exceed 35°C.

3) The unit should not be installed in any area where heat and steam are generated. The unit should not be installed, for example, next to a conven-

tional surface unit. Refer to the "INSTALLATION Instructions".

4) Exhaust vents are provided on the back of the unit for proper cooling and air flow in the cavity. To permit adequate ventilation, be sure to install so

as not to block these vents. There should be some space for air circulation.

5) Be sure the exterior of the cooking container and the interior of the oven are dry. Wipe off any moisture with a dry cloth or paper towel.

6) The Sensor works with food at normal storage temperature. For example, chicken pieces would be at refrigerator temperature and canned soup at

room temperature.

7) Avoid using aerosol sprays or cleaning solvents near the oven while using Sensor settings. The sensor will detect the vapor given of by the spray

and turn off before food is properly cooked.

8) After the oven is started on sensor cooking condition, if the sensor has not detected the vapor of the food, ERROR will appear and the oven will

shut off.

Water load cooking test

WARNING: The oven should be fully assembled before following procedure.

Make sure the oven has been plugged in at least two minutes before checking sensor cook operation. The cabinet should be installed and screws

tightened.