Operation Sequence - Sharp R-5L16 Service Manual

R-5L16
OFF CONDITION
1. When the timer knob is at "
2. Closing the oven door activates the primary latch switch
SW1, the 2nd latch switch SW2, and the 3rd latch switch
SW3.
IMPORTANT:
When the oven door is closed, the contacts COM-NC of the
monitor switch SW5 must be open.
Figure O-1 on page 22
3. When the microwave oven is plugged in a wall outlet
(220-230V, 50Hz), the noise filter is energized.
4. When the oven door is opened, the oven lamp lights.
MICROWAVE COOKING CONDITION
HIGH COOKING
When the door is closed, the contacts COM-NO of the
primary latch, 2nd latch and 3rd latch switches SW1 + SW2
+ SW3 are activated.
When the microwave power control is set to " HIGH " position
and cooking time is selected by turning the timer and push
the start button, the following operations occur: (Figure 0-2)
1. The contacts of the timer motor and vari switch are closed.
2. The contacts (COM-NO) of the cook switch are closed.
3. Then following components are energized.
Oven lamp
Timer motor
Turntable motor
Surge relay RY2
The line voltage is supplied to the primary winding of the
high voltage transformer. The voltage is converted to
about 3.3 volts A.C. on the filament winding, and
approximately 2000 volts A.C. on the secondary winding.
4. The 3.3 volts filament winding voltage heats the magnetron
filament and the 2000 volts secondary winding voltage is
sent to a voltage doubler circuit, where it is doubled to a
negative voltage of approximately DC 4000 volts.
5. The 2450MHz microwave energy produced in the
magnetron generates a wave length of 12.24 cm. This
energy is changed through the waveguide (transport
channel) into the oven cavity, where the food is placed to
be cooked.
6. Upon completion of the selected cooking time, the timer
bell rings, and contacts of the timer are open, then the
activated components as item 2 are de-energized.
7. When the door is opened during a cooking cycle, the
switches come to the following positions.
Switch Contact
primary latch Switch COM-NO
COM-NC
2nd latch switch COM-NO
Monitor Switch COM-NC
3rd latch switch COM-NO

OPERATION SEQUENCE

•
", the oven is OFF condition.
High voltage transformer
Fan motor .
Magnetron
Relay RY1
Condition
Durning Oven Door
Cooking Open(No cooking)
Closed Opened
Opened Closed
Closed Opened
Opened Closed
Closed Opened
8. MONITOR SWITCH CIRCUIT
The monitor switch SW5 is mechanically controlled by the
oven door and monitors the operation of the relay RY1.
8-1. When the oven door is opened during or after a cooking
cycle, the primary latch switch SW1 and the 3rd latch
switch SW3 must open their contacts (COM-NO) first.
After that the contacts (COM-NC) of the monitor switch
SW3 can be closed and the 2nd latch switch SW2 must
open its contacts (COM-NO). And then the cook switch
SW4 must open its contacts (COM-NO).
8-2. When the oven door is closed, the contacts (COM-NC)
of the monitor switch SW5 must be opened.
8-3. When the oven door is opened and the contacts of the
relay RY1 remain closed, the fuse F6.3A F1 will blow,
because the contacts (COM-NC) of the monitor switch
SW5 are closed and a short circuit is caused through the
relay RY1, the monitor resistor R1 monitor switch SW5,
and the fuse F6.3A F1
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, the 220-230 volts A.C. power is supplied to the high
voltage transformer intermittently within a 26.4-second time
base through the vari switch. The following levels of micro-
wave power are given.
SETTING
26.4 sec. ON
HIGH
20.4 sec. ON
MEDIUM HIGH
14.5 sec. ON
MEDIUM
8.6 sec. ON
MEDIUM LOW
4.4 sec. ON
LOW
Note: The ON/OFF time ratio does not exactly correspond
to the percentage of microwave power, because
approx. 3 seconds are needed for heating up the
magnetron filament.
4
6 sec. OFF
Approx. 70%
11.9 sec. OFF
Approx. 50%
17.8 sec. OFF
Approx. 30%
22 sec. OFF
Approx. 10%