Procedure L: Relay Test; Procedure M: Defrost Test; Procedure N: Foil Pattern On The Printed Wiring Board Test - Sharp R-220KK Service Manual

G1 G2
6
3
TIMER
COOK
CLOCK
SOFTEN 9
[14] Procedure L : 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. 1 of the 3 pin connector (A) and the normal open terminal of the relay RY2 on the con-
trol 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 good, control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE
RY1
RY2
8. If any abnormal condition is defected, replace the control unit.
9. Disconnect the power supply cord and then remove outer case.
10.Open the door and block it open.
11.Discharge high voltage capacitor.
12.Reconnect all leads removed from components during testing.
13.Re-install the outer case (cabinet).
14.Reconnect the power supply cord after the outer case is installed.
15.Run the oven and check all functions.
[15] Procedure M : 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 "DEFROST " pad once.
3. The oven is in Defrost cooking condition.
4. The oven will operate as follows.
MENU 1ST STAGE
Steaks/
LEVEL TIME
Chops
0.5lb 70% 1min 2sec.
5. If improper operation is indicated, the control unit is probably defective and should be checked.
[16] Procedure N : 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.
G3 G4 G5
2
WARM
DEFROST
REHEAT
POWER
4
5
POPCORN
LEVEL
0 1
CLEAR
START
8 7
MELT
MINUTE PLUS
Approx. 12.5V D.C. Oven lamp / Turntable motor / Cooling fan motor
Approx. 11.2V D.C. Power transformer
2ND STAGE 3RD STAGE
LEVEL TIME LEVEL
0% 50sec. 50%
G6
Pin NO. G1
G7
G8
STOP
G9
G10
CONNECTED COMPONENTS
4TH STAGE
TIME LEVEL TIME
37sec. 30% 40sec.
8 – 6
Pin NO. G10
Key unit ribbon
cable
Key unit (Membrane Switch) front view
R220KW