6
R-1870
R-1871
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
The following is a description of component functions
duringovenoperation.
OFF CONDITION
Closing the door activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switchcontactsare opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
controlunit.(FigureO-1).
1. The display will show SHARP, SIMPLY, THE, BEST,
PRESS, CLEAR, and PRESS, CLOCK.
Toset anyprogram or setthe clock,youmust firsttouch
the STOP/CLEAR pad. The display will clear, and " : "
willappear.
COOKING CONDITION
Programdesiredcookingtime touchingtheNUMBER
pads. When the START pad is touched, the following
operationsoccur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(Fordetails,refertoFigure O-2)
RELAY CONNECTEDCOMPONENTS
RY1 Ovenlamp
RY2 Powertransformer/Stirrermotor
RY4 Turntablemotor
RY5 Fanmotor
2. 120 volts A.C. is supplied to the primary winding of the
powertransformerandisconvertedtoabout3.3voltsA.C.
output on the filament winding, and approximately 2000
volts A.C. on the high voltage winding.
3. Thefilamentwindingvoltageheatsthemagnetronfilament
andtheH.V.winding voltageissentto avoltagedoubler
circuit.
4. The microwave energy produced by the magnetron is
channelled through the waveguide into the cavity feed-
box, and then into the cavity where the food is placed to
becooked.
5. Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generationofmicrowaveenergyisstopped.Theovenwill
revert to the OFF condition.
6. When the door is opened during a cook cycle, monitor
switch,doorsensingswitch,primaryswitchandsecondary
switch and secondary interlock relay are activated with
thefollowingresults.Thecircuitstothe stirrermotor,the
cooling fan motor, the turntable motor, and the high
voltage components are de-energized, and the digital
read-outdisplaysthetimestillremaininginthecookcycle
whenthedoorwasopened.
7. Themonitorswitchiselectricallymonitoringtheoperation
of the primary and secondary switch and secondary
interlock relay and is mechanically associated with the
door so that it will function in the following sequence.
(1) When the door opens from a closed position, the
secondaryinterlockrelay,doorsensingswitch, primary
and secondary switch open their contacts, and then
the monitor switch contacts close.
(2) When the door is closed from the open position, the
monitor switch contacts first open, and then the
contactsof the primaryand secondary switchclose.
If the primary switch, secondary switch and secondary
interlock relay fail with their contacts closed when the door
is opened, the closing of the monitor switch contacts will
form a short circuit through the monitor fuse, secondary
switch switch, primary switch and secondary interlock
relay, causing the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
WhenVariableCookingPowerisprogrammed,the120
volts A.C. 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.Microwave power operation is asfollows:
VARI-MODE ON TIME OFF TIME
Power10(P-HI) 32 sec. 0 sec.
(100%power)
Power9(P-90) 30 sec. 2 sec.
(approx.90%power)
Power8(P-80) 26 sec. 6 sec.
(approx.80%power)
Power7(P-70) 24 sec. 8 sec.
(approx.70%power)
Power6(P-60) 22 sec. 10 sec.
(approx.60%power)
Power5(P-50) 18 sec. 14 sec.
(approx.50%power)
Power4(P-40) 16 sec. 16 sec.
(approx.40%power)
Power3(P-30) 12 sec. 20 sec.
(approx.30%power)
Power2(P-20) 8 sec. 24 sec.
(approx.20%power)
Power1(P-10) 6 sec. 26 sec.
(approx.10%power)
Power0(P-0) 0 sec. 32 sec.
(0%power)
Note: TheON/OFFtimeratiodoesnotcorrespondwiththe
percentageofmicrowavepower,becauseapprox.2
seconds are needed for heating of the magnetron
filament.
