Service manual

14
KB-5121KS/K/W
1. Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER
DISASSEMBLY" page 32.
2. Open the drawer 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 covers and check voltage between Pin Nos. 1 and 3 of the 2 pin connector (CN-B) on the
power unit with an A.C. voltmeter.
The meter should indicate 116 or 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. 18V D.C. Oven lamp / Stirrer motor
RY2 Approx. 18V D.C. Power transformer
RY3 Approx. 18V D.C. Oven common relay
RY4 Approx. 18V D.C. Top heater
RY5 Approx. 24V D.C. Fan motor (Microwave)
RY6 Approx. 24V D.C. Fan motor (Oven)
RY7 Approx. 24V D.C. Oven lamp (Oven)
RY8 Approx. 24V D.C. Door lock motor (Oven)
RY9 Approx. 24V D.C. Convection motor
RY10 Approx. 24V D.C. Warmer (Cook top)
RY11 Approx. 24V D.C. Switching power supply
RY-B Approx. 24V D.C. Bottom heater
RY-C Approx. 24V D.C. Convection heater
C RELAY TEST
4) Reconnect all leads removed from components during testing.
5) Re-install the covers.
6) Reconnect the power source after the outer case is installed.
7) Run the oven and check all functions.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
B KEYBOARD UNIT TEST
1. Disconnect the power source, and then disassemble as per "COOK TOP/MICROWAVE DRAWER
DISASSEMBLY" page 32.
2. Open the drawer and block it open.
3. Discharge high voltage capacitor.
4. If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the wire harness and
connectors are making good contact between the control unit and the keyboard, verify that the door
sensing switch operates properly; that is the contacts are closed when the door is closed and open
when the door is open.
5. Remove the old keyboard unit and install the new keyboed unit (as the normal keyboard unit).
6. Reconnect the wire harness to the keyboard unit.
7. If the control unit responds by clearing with a beep when the stop/clear pad is touched, the old keyboard
unit is faulty and must be replaced. If the control unit does not respond, it is faulty and must be replaced.
If a specific pad does not respond, the above method may be used (after clearing the control unit) to
determine if the control unit or keyboed unit is at fault.
8. Reconnect all leads removed from components during testing.
9. Re-install the covers.
10.Reconnect the power source after the outer case is installed.
11.Run the oven and check all functions.