R-950A
8
TURNTABLE MOTOR
The turntable motor drives the turntable supporting plate
to rotate the turntable.
CONVECTION MOTOR
The convection motor drives the convection fan and
provides the heated air.
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 va-
pours given off from the heating foods. It is then exhausted
through the exhausting air vents at the oven cavity.
CONVECTION HEATER
The convection heater is located at the left side of the oven
cavity. It is intended to heat air driven by the convection
fan. The heated air is kept in the oven and force-circulated
and reheated by the convection heater.
GRILL HEATER
The grill heater is provided to brown the food and is located
on the top of the oven cavity.
CONVECTION COOKING SYSTEM
This oven is designed with a hot air heating system where
food is not directly heated by the convection heater, but is
heated by forced circulation of the hot air produced by the
convection heater. The air heated by the convection
heater is circulated through the convection passage pro-
vided on the outer casing of the oven cavity by means of
the convection fan which is driven by the convection
motor. It then enters the inside of the oven through the vent
holes provided on the left side of the oven. Next, the hot air
heats the food on the turntable and leaves the oven cavity
through the vent in the oven cavity left side wall. Without
leaving the oven, this hot air is reheated by the convection
heater, passes through the convection passage and en-
ters the inside of the oven cavity again, in a continuing
cycle. In this way, the hot air circulates inside the oven
cavity to raise its temperature and, at the same time,
comes into contact with the food being cooked. When the
temperature inside the oven cavity reaches the selected
temperature, the convection heater is de-energized. When
the temperature inside the oven cavity drops below the
selected temperature, the convection heater is energized
again. In this way, the inside of the oven cavity is main-
tained at approximately the selected temperature.
When the convection time reaches 0, the convection
heater is de-energized and the convection fan stops
operating and the oven shuts off. Upon completion of the
cooking time, the audible signal will sound, and oven lamp,
turntable motor, cooling fan motor and convection motor
are de-energized. At the end of the convection cycle, if the
cavity air temperature is above 118˚C, the circuit to RY6
will be maintained (by the thermistor circuit) to continue
operation of the cooling fan motor until the temperature
drops below 118˚C, at which time the relay will be de-
energized, turning off the fan motor. Relay RY5 will how-
ever, open as soon as the convection cycle has ended,
turning off the convection fan motor. This will now cool and
allow the damper door to open.
fan motor is interrupted, the air inlet duct is blocked or the
ventilation openings are obstructed, the fuse blows and
cuts off the power supplying to all electrical parts. The
defective fuse must be replaced with new rated one.
FUSE M10A 250V
1. If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock or
fire hazard.
2. The fuse also blows when1st. latch switch and 2nd.
interlock relay remain closed with the oven door open
and when the monitor switch closes.
3. The fuse M10A also blows when asymmetric rectifier,
H.V. rectifier, H.V. wire harness, H.V. capacitor,
magnetron or secondary winding of power transformer
is shorted.
FUSE 20A
If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock or fire
hazard.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that pre-
vents current flow ins both directions. And it prevents the
temperature rise of the power transformer by blowing the
fuse M10A when the high voltage rectifier is shorted.
D2 D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE
RECTIFIER
The rated peak reverse voltage of D1 of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2 of the
asymmetric rectifier is 1.7 KV. D1 and D2 of the asymmet-
ric rectifier or high voltage rectifier are shorted when the
each peak reverse voltage goes beyond the each rated
peak reverse voltage. (The process of blowing the fuse
M10A.) .
1. The high voltage rectifier is shorted by any causes
when microwave cooking.
2. The peak reverse voltage of D2 of the rectifier goes
beyond the rated peak reverse voltage 1.7 KV in the
voltagedoubler circuit.
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high voltage
winding of the power transformer.
5. The large electric currents beyond 10A flow through
the primary winding of the power transformer.
6. The fuse M10A blows by the large electric currents.
7. The power supply to the power transformer is cut off.
THERMISTOR
The thermistor is a negative temperature coefficient type.
The temperature in the oven cavity is detected through the
resistance of the thermistor, and then the control unit
causes the heating element relay to operate, thus the
current to the heating element is turned ON/OFF.
MONITOR RESISTOR
The monitor resistor prevents the fuse M10A 250V burst-
ing when the fuse M10A 250V blows due to the operation
of the monitor switch.
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