Relay Test - KitchenAid KOMS155MBL Technical Education

1. Disconnect the power supply cord.
2. Remove the unit from the wall (see page
2-1).
3. Remove the cabinet (see page 4-2).
4. Open the door and block it open.
5. To discharge the high voltage capacitor,
wait for 60 seconds.
6. Disconnect the leads to the primary of the
power transformer. Ensure that these leads
remain isolated from other components and
oven chassis by taping them using insula-
tion tape.
7. Reconnect the power supply cord.
8. Check the voltage between the normally-
open terminal of relay RY2, and the nor-
mally-open terminal of relay RY1 on the
control unit with an AC voltmeter. The meter
should indicate 120 volts. If not, check the
oven circuit.
RELAY SYMBOL
RY1
RY2(COOK)
RY3
RY4

RELAY TEST

OPERATIONAL VOLTAGE
Approx. -26.3V D.C.
Approx. -25.3V D.C.
Approx. -26.3V D.C.
Approx. -26.3V D.C.
RY1, RY2, RY3 & RY4 RELAYS
These relays are operated by DC voltage.
Check the voltage at the relay coil with a DC
voltmeter during the microwave cooking op-
eration.
If a DC voltage is indicated, the relay is defec-
tive. If a DC voltage is not indicated, check the
diode that is connected to the relay coil. If the
diode is good, the control unit is defective.
1. Disconnect the power supply cord.
2. Open the oven door and block it.
3. To discharge the high voltage capacitor,
wait for 60 seconds.
4. Reconnect all of the leads that were re-
moved from components during testing.
5. Reinstall the cabinet.
6. Reconnect the power supply cord.
7. Run the oven and check all the functions.
CONNECTED COMPONENTS
Oven lamp / Fan motor / Turntable motor
Power transformer
Hood lamp
Hood lamp
6-4