Sharp R-1482 Service Manual page 21

PROCEDURE
LETTER
N RELAY TEST
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 No. 7 of the 4 pin connector (A) and the
common terminal of the relay RY1 on the control unit with an A.C. voltmeter.
The meter should indicate 120 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
RELAY SYMBOL
RY1
RY2(COOK)
RY3
RY4
RY5
8.Disconnect the power supply cord, and then remove outer case.
9.Open the door and block it open.
10.Discharge high voltage capacitor.
11.Reconnect all leads removed from components during testing.
12.Re-install the outer case (cabinet).
13.Reconnect the power supply cord after the outer case is installed.
14.Run the oven and check all functions.
O COMPU DEFROST TEST
(1) Place one cup of water in the center of the turntable tray in the oven cavity.
(2) Close the door, touch the " COMPU DEFROST " pad once and touch the Number pad "1" and touch
the Number pad "5". And then touch the "START" pad.
(3) The oven is in Compu Defrost cooking condition.
(4) The oven will operate as follows
WEIGHT
0.5lbs
(5) If improper operation is indicated, the control unit is probably defective and should be checked.
P FOIL PATTERN ON THE PRINTED WIRING BOARD TEST
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.
1. Foil pattern check and repairs.
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) Follow the troubleshooting guide given below for repair.
TEST PROCEDURES
COMPONENT TEST
good, control unit is defective.
OPERATIONAL VOLTAGE
Approx. 24.0V D.C.
Approx. 24.0V D.C.
Approx. 24.0V D.C.
Approx. 24.0V D.C.
Approx. 24.0V D.C.
1ST STAGE 2ND STAGE
LEVEL TIME LEVEL
70% 35sec. 0%
19
CONNECTED COMPONENTS
Oven lamp / Fan motor / Stirrer motor
Power transformer
Turntable motor
Hood motor
Hood motor (HIGH /LOW selection)
3RD STAGE
TIME LEVEL TIME
40sec. 50% 30sec.
R-1480
R-1481
R-1482
4TH STAGE
LEVEL TIME
30% 35sec.