6
R-2275
R-2285
FUSE F6.3A 250V F2
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 when 1st latch switch SW1 remains
closed with the oven door open and when the monitor
switch SW4 closes.
ASYMMETRIC RECTIFIER AND WEAK POINT /
FUSE WP1 WP2
The asymmetric rectifier is solid state device that prevents
current flow is both directions. And it prevents the tempera-
ture rise of the high voltage transformer by blowing the weak
point / fuse WP1 or WP2 when the high voltage rectifier is
shorted.
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 asymmetric
rectifier or high voltage rectifier are shorted when the each
peak reverse voltage goes beyond the each rated peak
reverse voltage. (The process of the blowing the weak point
/ fuse WP1 or WP2)
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
voltage doubler circuit.
A
B
C
D2
D1
ASYMMETRIC
RECTIFIER
HIGH VOLTAGE RECTIFIER
3. D2 of the rectifier is shorted.
4. The large electric currents flow through the high voltage
winding of the high voltage transformer.
5. The large electric currents flow through the primary
winding of the high voltage transformer.
6. The weak point / fuse WP1 or WP2 blows by the large
electric currents.
7. The power supplying to the high voltage transformer is
cut off.
THERMISTOR (EXHAUST)
The thermistor is a negative temperature coefficient type.
The temperature in the exhaust duct is detected through the
resistance of the thermistor.
If the temperature rises about 120˚C, the control panel will
display “EE 7” and the oven will stop to avoid overheating
and catching fire.
THERMISTOR (AIR INTAKE)
This thermistor detects air flow around it. When air intake
filter is blocked by dust or blower motor is stalled, an air flow
reduces and the touch control panel shows “FILTER” on
display. To cancel “FILTER” indication, touch the START
pad.
SURGE RELAYS RY-S1 AND RY-S2 AND
SURGE RESISTORS R1 AND R2
When the START key is touched the contacts of the surge
relays RY-S1 + RY-S2 close and the surge current flows
through the surge resistors R1 + R2 for 200 msec after 20
msec. since the START key is touched the surge relays RY-
S1+RY-S2 closes and supply the high voltage transformer
with the line voltage. After 200 msec. the surge relays RY-S1
+ RY-S2 open their contacts and gets out of function.
The surge resistors R1 + .R2 lets the current (peak current)
flow when the oven is switched on. If surge resistors are
defective, the home fuse or circuit breaker may break down
when the oven is switched on.
CAUTION; THE SURGE RELAYS RY-S1+RY-S2 CLOSE
FOR ONLY 200 MSEC. JUST WHEN THE OVEN
GETS RESTARTED, BUT OPENS AGAIN.
WITHIN THIS 200 MSEC., THE RELAYS RY-3
+ RY-4 MUST CLOSE.
BLOWER MOTOR BM
The blower motor drives a blade which draws external cool
air. This cool air is directed through the air vanes surrounding
the magnetrons and cools the magnetrons. This air is chan-
nelled through the oven cavity to remove steam and vapours
given off from the heating foods. It is then exhausted through
the exhausting air vents at the oven cavity.
MG THERMAL CUT-OUTS 145˚ TC1, TC2
These thermal cut-outs protect the magnetrons against
overheat. If their temperature go up higher than 145˚C
because the blower motor is interrupted, the ventilation
openings are blocked, the thermal cut-outs TC1+TC2 will
open and the line voltage to the high voltage transformer
T1+T2 will be cut off and the operations of the magnetrons
MG1+MG2 will be stopped. The thermal cut-outs TC1+TC2
will close their contacts again when their temperatures go
down lower than -20˚C.
BLOWER MOTOR THERMAL CUT-OUT 115˚C
TC3
This thermal cut-out protect the blower motor against over-
heat. If its temperature goes up higher than 115˚C because
the blower motor is locked or the ventilation openings are
blocked, the contacts of the thermal cut-out TC3 will open
and the line voltage to the control unit will be cut off and the
operation of the oven will be stopped. The thermal cut-out
TC3 will be close its contacts again when its temperature
goes down lower than -20˚C.
OVEN TEMP. FUSE 150˚C TF
This temp. fuse protects the oven against overheat. If the
temperature goes up higher than 150˚C because the food
catches fire, the contacts of temp. fuse TF will open and the
line voltage to the control unit will be cut off and the operation
of the oven will be stopped. The defective temp. fuse must be
replaced with a new rated one.
