Theory Of Operation; Microwave Operating Sequence - KitchenAid KOMS155MBL Technical Education

MICROWAVE OPERATING SEQUENCE

OFF CONDITION
Closing the door activates the secondary (door
sensing) interlock switch, and the primary in-
terlock switch. The monitor switch contacts are
opened.
When the oven is plugged in, 120 VAC is
supplied to the control unit (see the illustration
below).
1. The display will show "WELCOME." To
set any program or set the clock, you must
first touch the STOP/CLEAR keypad. The
display will clear, and a colon ( : ) will
appear.
POWER LEVEL (P-0 TO P-90)
COOKING
When "Variable Cooking Power" is pro-
grammed, 120 VAC is supplied to the power
transformer intermittently through the contacts
of relay RY2, which is operated by the control
unit within an interval second time base.
NOTE: " " indicates components with potential above 250V.
CAVITY
TEMPERATURE FUSE
A1
FUSE
20A
GRN
GND
120 V AC.
60 Hz
HL

THEORY OF OPERATION

MAGNETRON
TEMPERATURE FUSE
CONTROL UNIT
N.O.
RY3
SECONDARY
INTERLOCK
OVEN LAMP
RELAY
RELAY
RY1
RY4
N.O. COM.
A3 A5
HOOD
LAMP
HL
OL
Oven Schematic-Off Condition
Microwave power operation is as follows (the
indicated power is approximate):
VARI-MODE
HIGH (100% power)
P-90 (90% power)
P-80 (80% power)
P-70 (70% power)
P-60 (60% power)
P-50 (50% power)
P-40 (40% power)
P-30 (30% power)
P-20 (20% power)
P-10 (10% power)
P-0 (0% power)
NOTE: The ON/OFF time ratio does not corre-
spond with the percentage of microwave
power, because approximately 3 seconds are
needed for heating of the magnetron filament.
COM.
B1
DOOR
SENSING
SWITCH
B2
RY2
F1
F2
F3
FM
TTM
PRIMARY
INTERLOCK
SWITCH
3-1
ON TIME OFF TIME
32 sec. 0 sec.
30 sec. 2 sec.
26 sec. 6 sec.
24 sec. 8 sec.
22 sec. 10 sec.
18 sec. 14 sec.
16 sec. 16 sec.
12sec. 20 sec.
8 sec. 24 sec.
6 sec. 26 sec.
0 sec. 32 sec.
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CLOCK APPEARS ON DISPLAY.
POWER
TRANSFORMER
HIGH VOLTAGE
CAPACITOR
1.0 F/ AC2300V
HIGH VOLTAGE
RECTIFIER