Sharp R-1880LS Service Manual page 29

PROCEDURE
LETTER
S RELAY TEST
1. Disconnect the power supply cord, and then remove outer case.
. 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. 5 of the 3-pin connector (A) and the common
terminal of the relay RY1 on the control unit with an A.C. voltmeter. The meter should indicate 10 volts, if
not check oven circuit.
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
RELAY SYMBOL
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.
1. 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.
T TIMED DEFROST TEST
1. Place one cup of water in the center of the turntable tray in the oven cavity.
. Close the door, touch the " DEFROST " pad four times.
3. Touch the number 5 pad.
4. Touch " START " pad.
5. The oven will operate as follows.
MENU
CHICKEN
PIECES
6. If improper operation is indicated, the control unit is probably defective and should be checked.
TEST PROCEDURES
defective.
OPERATIONAL VOLTAGE
RY1 Approx. 4.0V D.C.
RY(COOK) Approx. 4.0V D.C.
RY3 Approx. 4.0V D.C.
RY4 Approx. 4.0V D.C.
RY5 Approx. 4.0V D.C.
RY6 Approx. 4.0V D.C.
RY7 Approx. 4.0V D.C.
RY8 Approx. 4.0V D.C.
RY9 Approx. 4.0V D.C.
RY10 Approx. 4.0V D.C.
WEIGHT 1ST STAGE
(LBS) LEVEL TIME
0.5 70% 8sec.
COMPONENT TEST
CONNECTED COMPONENTS
Oven lamp
Power transformer / Stirrer mootor
Heating element
Turntable motor
Fan motor
Damper motor
Convection motor
Hood lamp
Hood motor
Hood motor (HIGH / LOW selection)
ND STAGE
LEVEL TIME LEVEL
50% 5sec. 30%
9
3RD STAGE
TIME
1min.8sec.
R-1880LS/LST