Sharp R-230HW Service Manual - Page 18

R-203HW R-220HW R-230HW TEST PROCEDURES PROCEDURE LETTER K RELAY TEST COMPONENT TEST 1. Disconnect the power supply cord and then remove outer case. 2. Open the door and blocked 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. 3 of the 2 pin connector (A) and the normal open terminal of the relay RY2 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 good, control unit is defective. RELAY SYMBOL RY1 RY2 OPERATIONAL VOLTAGE Approx. 12.0V D.C. Approx. 12.0V D.C. CONNECTED COMPONENTS Oven lamp / Turntable motor / Cooling fan motor Power transformer 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. L 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, the number pad " 2 " for selecting " Steaks/Chops " and the number pad " 5 " for enterring 0.5 lbs in weight. And then touch the " START " pad. (3) The oven is in Defrost cooking condition. (4) The oven will operate as follows. MENU DEFROST 0.5lb 1ST STAGE LEVEL TIME 70% 35sec. 2ND STAGE LEVEL TIME 50% 52sec. 3RD STAGE LEVEL TIME 30% 45sec. (5) If improper operation is indicated, the control unit is probably defective and should be checked. M 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. 16