15
R-209HK
R-209HW
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
When testing is completed,
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) Reconnect all leads removed from components during testing.
5) Re-install the outer case (cabinet).
6) Reconnect the power supply cord after the outer case is installed.
7) Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
J
KEY UNIT 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.
Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check the circuit
between the pins of the key unit that correspond to the STOP/CLEAR pad. When the pad is pressed, the
ohmmeter should indicate short circuit. When the pad is released, the ohmmeter should indicate open
circuit. If incorrect readings are obtained, the key unit is faulty and must be replaced. About the other pads,
the above method may be used.
5. Reconnect all leads removed from components during testing.
6. Re-install the outer case (cabinet).
7. Reconnect the power supply cord after
the outer case is installed.
8. Run the oven and check all functions.
1
2
3
4
5
6
7
8
9
0
POWER
LEVEL
MINUTE
PLUS
COOK
DEFROST
POPCORN
REHEAT
START
TIMER
CLOCK
G 1
G 2
G 3
G 4
G 5
G 6
G 7
G 8
G 9
G10
STOP
CLEAR
Pin
NO. G1
Pin
NO. G10
Key unit ribbon cable
Key unit (Membrane Switch) front view
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
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 12.0V D.C.
Oven lamp / Turntable motor / Cooling fan motor
RY2
Approx. 12.0V D.C.
Power transformer
K
RELAY TEST
