R-657SL (serv.man15). Operation Sequence - Sharp Home Appliance User Guide / Operation Manual

r-657sl (serv.man15) user guide / operation manual
Model
R-657SL (serv.man15)
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2 Few pages! See other manuals at the bottom of the first or last page.
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Document
User Guide / Operation Manual
Brand
Device
Home Appliance / Microwave Oven / Operation Sequence
File
r-657sl-sm15.pdf
Date

Read Sharp R-657SL (serv.man15) User Guide / Operation Manual online

R657(W)
5 – 1
R657(W)
Service Manual
 
CHAPTER 5. 
OPERATION SEQUENCE
[1] MICROWAVE OFF CONDITION
Closing the door activates the door interlock switch (monitored latch
switch).
IMPORTANT
When the oven door is closed, the the monitor switch contacts
COM-NC must be open. When the microwave oven is plugged in a
wall outlet (230 - 240V / 50Hz), the noise filter is energised.
                                            Figure O-1 on page 13-1 
NOTE: When the oven door is opened, the oven lamp comes on at
this time.
[2] MICROWAVE COOKING CONDITION
1. HIGH COOKING
Enter a desired cooking time by touching the time keys and start the
oven by touching START key.
Function sequence 
                           Figure O-2 on page 13-1
1. The line voltage is supplied to the primary winding of the high volt-
age transformer. The voltage is converted to about 3.3 volts A.C.
output on the filament winding and high voltage of approximately
2000 volts A.C. on the secondary winding.
2. The filament winding voltage (3.3 volts) heats the magnetron fila-
ment and the high voltage (2000 volts) is sent to the voltage dou-
bling circuit, where it is doubled to negative voltage of
approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the magnetron gen-
erates a wavelength of 12.24 cm. This energy is channelled
through the waveguide (transport channel) into the oven cavity,
where the food is placed to be cooked.
4. When the cooking time is up, a signal tone is heard and the relays
RY1 + RY3 + RY4 go back to their home position. 
The circuits to the oven lamp, high voltage transformer, fan motor
and turntable motor are cut off.
5. When the oven door is opened during a cooking cycle, the switches
come to the following condition.
The circuit to the high voltage transformer, fan motor and turntable
motor are cut off when the monitored latch switch is open. The oven
lamp remains on even if the oven door is opened after the cooking
cycle has been interrupted, because the relay RY1 stays closed.
Shown in the display is the remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by the oven door,
and monitors the operation of the monitored latch switch, the relay
RY1 and the relay RY3.
1) When the oven door is opened during or after the cycle of a
cooking program, the monitored latch switch and stop switch
must open their contacts (COM-NO) first. After that the contacts
(COM - NC) of the monitor switch can be closed.
2) When the oven door is closed, the contacts (COM - NC) of the
monitor switch must be opened first. The contacts (COM - NO)
of the monitored latch switch and stop switch are closed after.
3) When the oven door is opened and the contacts of the moni-
tored latch switch, the relay RY1 and the relay RY3 remain
closed, the fuse F8A will blow, because the monitor switch is
closed and a short circuit is caused.
2. MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking power, the
line voltage is supplied to the high voltage transformer intermittently
within a 32-second time base through the vari contact. The following
levels of microwave power are given.
SETTING;
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.
[3] GRILL COOKING CONDITION
1. GRILL (Figure O-3)
In this condition the food is cooked by the grill heating element energy.
Enter the grilling time by touching the time keys. And then touch the
GRILL key and start the oven by touching the START key.
 The following operations occur:
1. The numbers on the display start the count down to zero.
2. The oven lamp, cooling fan motor and turntable motor are ener-
gized. 
3. The relay RY2 is energized and the main supply voltage is applied
to the grill heating element.
4. Now, the food is cooked by the grill heating element.
[4] DUAL COOKING CONDITION
1. DUAL GRILL (Figure O-4)
In this condition the food is cooked by the microwave energy and grill
heating element energy. Enter the desired cooking time by touching
the time keys. And then touch the DUAL GRILL key, and start the oven
by touching the START key.
 The following operations occur:
1. The numbers on the display start the count down to zero.
2. The oven lamp, cooling fan motor and turntable motor are ener-
gized. 
CONNECTED COMPONENTS
RELAY
Oven lamp, Turntable motor 
RY1
High voltage transformer 
RY3
Fan motor, 
RY4
          CONDITION
SWITCH CONTACT 
DURING 
COOKING
DOOR OPEN 
(NO COOKING)
Monitor switch        
COM-NC
Opened
Closed
Monitored latch 
switch 
COM-NO Closed 
Opened
Stop switch   
COM-NO 
Closed 
Opened
100P(HIGH)
32 sec. ON
70P
(MEDIUM HIGH)
Approx. 70%
100%
24 sec. ON
8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
50P(MEDIUM)
Approx. 50%
18 sec. ON
30P
(MEDIUM LOW)
Approx. 30%
12 sec. ON
10P(LOW)
Approx. 10%
6 sec. ON
R657(W)
5 – 2
3. The relay RY2 is energized and the main supply voltage is applied
to the grill heating element.
4. The relay RY3 is energized and the microwave energy is generated
by magnetron.
5. Now, the food is cooked by the magnetron and the grill heating ele-
ment.
[5] FAN MOTOR OPERATION (in Grill and
Dual Grill)
Upon completion of the selected cooking time, the fan motor continues
to operate for 2 minutes (in case that the oven has been operated for
more than 3 minutes in Grill or Dual Grill cooking condition).
Page of 2
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