R-953/963M - 8
DOOR OPEN MECHANISM
The door can be opened by pushing the open button on the
control panel. When the open button is pushed, the open
lever is pushes lower latch head on the door upward. The
upper latch head is linked with the lower latch head, so
now, the door can be opened.
Figure D-1. Door Open Mechanism
MONITORED LATCH SWITCH
1. When the oven door is closed, the contacts (COM-NO)
of the switch must be closed. And the contacts (COM-
NC) must be opened.
2. When the oven door is opened, the contacts (COM-
NO) of the switch must be opened. And the contacts
(COM-NC) must be closed.
STOP SWITCH
1. When the oven door is closed, the contacts (COM-NO)
of the switch must be closed.
2. When the oven door is opened, the contacts (COM-
NO) of switch must be opened.
MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the
upper latch head on the door while the door is closed. The
switch is intended to render the oven inoperative by means of
blowing the fuse F8A when the contacts of the monitored
latch switch fail to open when the door is opened.
Function
1. When the door is opened, the contacts (COM-NC) of
monitor switch close (to the ON condition) due to their
being normally closed and contacts (COM-NO) open.
At this time the contacts (COM-NO) of monitored latch
switch is in the OFF condition (contacts open) due to
their being normally open contact switches.
2. As the door goes to a closed position, the monitor
switch contacts (COM-NC) are opened and contacts
(COM-NO) closed and then contacts (COM-NO) of
monitored latch switch and stop switch are closed. (On
opening the door, each of these switches operate
inversely.)
3. If the door is opened and the monitored latch switch
contacts (COM-NO) fail to open, the fuse F8A blows
immediately after closing of the monitor switch (COM-
NC) contacts.
CAUTION: BEFORE REPLACING A BLOWN FUSE F8A,
TEST THE MONITORED LATCH SWITCH
AND MONITOR SWITCH FOR PROPER
OPERATION. (REFER TO CHAPTER “TEST
PROCEDURE”).
FUSE 20A 250V
If the wire harness or electrical components are short-
circuited, this fuse 20A blows to prevent an electric shock
or fire hazard.
FUSE F8AH 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 when the monitored latch switch
remains closed with the oven door open and when the
monitor switch contact (COM-NC) closes.
3. The fuse also blows when the asymmetric rectifier,
H.V. rectifier,. H.V. wire harness, H.V. capacitor,
magnetron or secondary winding of high voltage trans-
former is shorted.
TC TRANSFORMER
T/C transformer converts A.C. line voltage into low voltage
to drive the control unit.
THERMAL CUT-OUT 125˚C (MG)
This thermal cut-out protects the magnetron against over-
heat. If the temperature goes up higher than 125˚C be-
cause the fan motor is interrupted or the ventilation open-
ings are blocked, the thermal cut-out will open and switch
off all the electrical parts. The defective thermal cut-out
must be replaced with a new one.
THERMAL CUT-OUT 170˚C (GRILL)
This thermal cut-out protects the oven against the over-
heat during grill cooking, convection cooking or dual
cooking. If the temperature rises above 170˚C because
the fan motor is interrupted, the air inlet duct is blocked or
the ventilation openings are obstructed, the thermal cut-
out opens and switches off all the electrical parts. When
the cools itself down to the operating temperature of
155˚C, the contacts of the thermal cut-out will close again.
THERMAL CUT-OUT 170˚C (CONV.)
This thermal cut-out protects the convection motor against
the overheat. If the temperature of the thermal cut-out
rises above 170˚C because the convection fan is inter-
rupted, the ventilation openings are obstructed or the
other abnormal matter occurs, the thermal cut-out opens
and switches off the convection heating element and the
other electrical parts. When the cools itself down to the
operating temperature of 155˚C, the contacts of the ther-
mal cut-out will close again.
ASYMMETRIC RECTIFIER
The asymmetric rectifier is solid state device that prevents
current flow is both directions. And it prevents the tem-
perature rise of the high voltage transformer by blowing
the fuse F8A when the high voltage rectifier is shorted.
FUNCTION OF IMPORTANT COMPONENTS
Latch hook
Door
Stop switch
Latch
Heads
Monitor switch
Monitored
latch switch
Tab
