Sharp R-3A54 User Manual

R-3A54
R-3E54
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM
The door can be opened by pushing the door open
button on the control panel. When the door open but-
ton is pushed, the switch lever is moved upward, op-
erating the latch head.
The latch head is moved
upward, and released from the latch hook. Now, the
door can be opened.
Door--&+
Switch
lever
Stop switch
‘.
‘. .\
*.
‘.
Figure D-l. Door Open Mechanism
IST LATCH, 2ND LATCH AND STOP SWITCHES
1. When the oven door is closed, the contacts (COM
2. When the oven door is opened, the contacts (COM
-NO) must be opened.
-NO) must be closed.
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 1st and 2nd latch switches fail
to open, the fuse M8A blows simultaneously with
closing the contacts (COM -NC) of the monitor
switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE F
M8A TEST THE IST AND 2ND LATCH
SWITCHES, MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION.
MONITOR RESISTOR R 0.8 I2 20W
The monitor resistor prevents the fuse M8A bursting
when the fuse M8A blows due to the operation of the
monitor switch.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is a solid state device that
prevents current flow in both directions. And it pre-
vents the temperature rise of the power transformer by
blowing the fuse M8A when the high voltage rectifier
is shorted.
The rated peak reverse voltage of Dl of the asymmetric
rectifier is 6 KV The rated peak reverse voltage of D2
of the asymmetric rectifier is 1.7 KV. Dl 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
blowing the fuse M8A.)
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.
6. The fuse M8A blows by the large electric currents.
7. The power supply to the all electrical parts is cut
off.
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 6.3A flow
through the primary widing of the power transfor-
mer.
FUSE M8A
1. The fuse M8A blows when the contacts
(COM -NO) of the 1 st latch switch and 2nd latch
switch remain closed with the oven door open and
when the monitor switch closes.
2. The fuse M8A also blows when asymmetric rectifier,
H.V. rectifier, H.V. wire harness, H.V. capacitor,
magnetron or secondary winding of power trans-
former is shorted.
3. If the wire harness or electrical components are
short-circuited, the fuse M8A blows to prevent an
electric shock of fire hazard.
THERMAL CUT-OUT 145°C (MG)
This thermal cut-out protects the magnetron against
overheat. If this temperature goes up higher than
145°C because the fan motor is interrupted, the venti-
lation openings are blocked, the thermal cut-out will
open and the line voltages to the power transformer
will be cut off and the operation of the magnetron will
be stopped.
The defective thermal cut-out must be
replaced with new one.

Sharp R-3A54 Specifications

General

Brand	Sharp
Model	R-3A54
Category	Microwave Oven
Language	English