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Model
R-216 (serv.man2)
Pages
32
Size
1.05 MB
Type
PDF
Document
Service Manual
Brand
Device
Home Appliance / Microwave Oven / Complete
File
r-216-sm2.pdf
Date

Sharp R-216 (serv.man2) Service Manual ▷ View online

R-216(W)
3
APPEARANCE VIEW
OVEN
CONTROL PANEL
7. Coupling
8. Control panel
9. Waveguide cover
10. Power supply cord
11. Turntable
12. Roller stay
1. Ventilation openings
2. Oven lamp
3. Door hinges
4. Door safety latches
5. See through door
6. Door seals sealing surfaces
NOTE: The oven is fitted with a safety feature. If the TIMER remains at the "0" position for more than 3 minutes,
the oven door must be opened or the MICROWAVE POWER LEVEL button must be pressed before the
dial can be operated again.
9
2
5
4
4
7
11
3
6
8
12
10
1
POWER LEVEL indicator
MICROWAVE POWER LEVEL button
ILLUMINATED TIMER (0 - 30 Min.)
DEFROST / COOK GUIDE
4
R-216(W)
OPERATION SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(monitored latch switch and 2nd. interlock relay control
switch).
IMPORTANT
When the timer knob is at "0" the oven in the OFF
condition.
When the oven door is closed, 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 and the control panel are
energized.
Figure O-1 on page 22
MICROWAVE COOKING CONDITION
HIGH COOKING
When the door is closed, the contacts (COM-NO) of the
monitored latch switch  and the monitor switch  are closed.
When the microwave power is set to HIGH position by
pressing the microwave power level button and cooking
time is selected by turning the timer knob, the following
components are energized: H.V. transformer, Magnetron,
Oven lamp, Turntable motor and Fan motor.
Function sequence
Figure O-2 on page 22
CONNECTED COMPONENTS
RELAY
Oven lamp, Fan motor, Turntable motor
RY1
High voltage transformer
RY2
1. 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. 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 filament and the high voltage (2000 volts) is
sent to the voltage doubling circuit, where it is doubled
to negative voltage of approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the
magnetron generates a wave length 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+RY2 open. The circuits to the oven
lamp, high voltage transformer, fan motor and turnta-
ble motor are cut off.
5. When the door is opened during a cook cycle, the
switches come to the following condition.
          CONDITION
DURING
DOOR OPEN
SWITCH
CONTACT
COOKING
(NO COOKING)
Monitored latch switch
COM-NO
Closed
  Open
Monitor switch
COM-NC
Open
  Closed
2nd. interlock relay
control switch
COM-NO
Closed
  Open
The circuits to the 
high voltage
 transformer, fan motor
turntable motor, and the oven lamp are cut off when the
monitored latch switch  and 2nd. interlock relay control
switch are made open.
6. MONITOR SWITCH CIRCUIT
The monitor switch  is mechanically controlled by oven
door, and monitors the operation of the monitored latch
switch.
6-1 When the oven door is opened during or after the
cycle of a cooking program, the monitored latch
switch  and 2nd. interlock relay control switch  must
open their contacts first. After that the contacts (COM-
NC) of the monitor switch  can be closed.
6-2. When the oven door is closed, the contacts (COM-
NC) of the monitor switch  must be opened first.  After
that the contacts (COM-NO) of the monitored latch
switch and 2nd. interlock relay control switch are
closed.
6-3. When the oven door is opened and the contacts
(COM-NO) of the monitored latch switch  remain
closed, the fuse T6.3A will blow, because the con-
tacts (COM-NC) of the monitor switch are closed and
a short circuit is caused.
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-seconds time base
through the relay contact which is coupled with the cur-
rent-limiting relay RY2. The following levels of microwave
power are given.
SETTING;
NOTE: The ON/OFF time ratio does not exactly corre-
spond to the percentage of microwave power,
because approx. 3 seconds are needed for heat-
ing up the magnetron filament.
POWER OUTPUT REDUCTION
After 100% power cooking mode is carried out for more
than 20 minutes, the power output is automatically reduced
to 70%. Even if the cooking time is shorter than for 20
minutes, the power output is reduced to 70% after total
cooking time over 20 minutes when the oven is started in
100% power cooking mode again within 1 minute and 35
seconds.
HIGH
32 sec. ON
MEDIUM HIGH
Approx. 70%
100%
24 sec. ON
8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
MEDIUM
Approx. 50%
18 sec. ON
MEDIUM LOW
Approx. 30%
12 sec. ON
LOW
Approx. 10%
6 sec. ON
R-216(W)
5
FUNCTION OF IMPORTANT COMPONENTS
THERMAL CUT-OUT 125˚C (OVEN)
The thermal cut-out located on the top of the oven cavity
is designed to prevent damage to the oven if the foods in
the oven catch fire due to over heating produced by
improper setting of cook time or failure of control unit.
Under normal operation, the thermal cut-out remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the thermal cut-out will
open at 125˚C, causing the oven to shut down. The
defective thermal cut-out must be replaced with a new
one.
THERMAL CUT-OUT 95˚C (MAGNETRON )
The thermal cut-out located on the top of the oven cavity
is designed to prevent damage to the magnetron if an over
heated condition develops in the tube due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the thermal cut-out will
open at  95˚C, causing the oven to shut down. When the
magnetron has cooled  to 75˚C, the thermal cut-out closes
and cook cycle will resume.
TURNTABLE MOTOR
The turntable motor drives the roller stay to rotate the
turntable.
FAN MOTOR
The fan motor drives a blade which draws external cool air.
This cool air is directed through the air vanes surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and
vapours given off from the heating foods. It is then ex-
hausted through the exhausting air vents at the oven
cavity.
NOISE FILTER
The noise filter prevents the radio frequency interference
that might flow back in the power circuit.
DOOR OPEN MECHANISM
The door is opened by pulling the door, refer to the Figure
D-1.
Figure D-1. Door Open Mechanism
MONITORED LATCH SWITCH  AD 2ND. INTER-
LOCK RELAY CONTROL SWITCH
1. When the oven door is closed, the contacts (COM-NO)
must be closed.
2. When the oven door is opened, the contacts (COM-
NO) must be opened.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COM-
NC) must be closed.
3. If the oven door is opened and the contacts (COM-NO)
of the monitored latch switch fail to open, the fuse
T6.3A blows simultaneously with closing the contacts
(COM-NC) of the monitor switch .
CAUTION: BEFORE REPLACING A FUSE TEST THE
MONITORED LATCH SWITCH AND
MONITOR SWITCH   FOR PROPER OP-
ERATION. (REFER TO CHAPTER "TEST
PROCEDURE".)
FUSE T6.3A
1. The fuse T6.3A blows when the contacts (COM-NO) of
the monitored latch switch remain closed with the oven
door open and when the monitor switch   closes.
2. If the wire harness or electrical components are short-
circuited, the fuse T6.3A blows to prevent an electric
shock of fire hazard.
HIGH VOLTAGE FUSE
The high voltage fuse blows when the high voltage rectifier
or the magnetron is shorted.
Latch Heads
Latch Hook
Door
Monitor
Switch
Monitored
Latch
Switch
2nd. Interlock
Relay Control
 Switch
6
R-216(W)
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the
checks. Many of the possible causes of trouble will require
that a specific test be performed. These tests are given a
procedure letter which will be found in the "Test Procedure
"section.
IMPORTANT: If the oven becomes inoperative because
of a blown fuse T6.3A in the monitored
latch switch  - monitor switch  circuit, check
the monitored latch switch and monitor
switch  before replacing the fuse T6.3A.
TROUBLESHOOTING GUIDE
MAGNETRON
HIGH VOLTAGE TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE WIRE
HIGH VOLTAGE CAPACITOR
MONITORED  LATCH SWITCH
2ND. INTERLOCK RELAY CONTROL SWITCH
MONITOR SWITCH
THERMAL CUT-OUT 125˚C (OVEN)
THERMAL CUT-OUT 95˚C (MG)
FAN MOTOR
TURNTABLE MOTOR
FUSE T6.3A
CONTROL PANEL
TACT SWITCH
RELAY 
RY1,
RELAY 
RY2,
FOIL PATERN ON P.W.B.
POWER SUPPLY CORD
SHORTED WIRE HARNESS
OPENED WIRE HARNESS
OVEN LAMP
WALL OUTLET
MISADJUSTMENT SWITCH
HOME FUSE OR BREAKER
BLOCKED COOLING FAN
BLOCKED VENTILATION
NOISE FILTER
H.V. FUSE
Home fuse blows when power
supply cord is plugged into wall
outlet.
FUSE T6.3A blows when
power supply cord is plugged
into wall outlet.
Oven does not start when the
timer is set.
Oven lamp does not light (Other
function is normal.)
Fan motor does not operate.
(Other function is normal.)
Turntable motor does not op-
erate. (Other function is nor-
mal.)
Oven or any electrical parts
does not stop when cooking
time is 0.
Oven seems to be operating
but little or no heat is produced
in oven load. (Microwave
power level is set at HIGH)
Oven does not seems to be
operating properly when
MEDIUM HIGH, MEDIUM,
MEDIUM LOW or LOW is set.
(Oven operates properly at
HIGH.)
Oven goes into cook cycle but
shuts down before end of cook-
ing cycle.
Oven lamp, turntable motor
and fan motor do not operate.
The microwave power level can
not be changed.
OFF
CONDITION
PROBLEM
CONDITION
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
ON
CONDITION
CK = Check / RE = Replace
A B C
CK
D E E E F   F   G  G   H   K   L M M N
RECKCKRE CKCKCK CK CK
I J
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