Sharp R-9320 Service Manual page 28

UPPER AND LOWER LATCH SWITCHES
The upper latch switch is mounted in the upper latch hook
and the lower latch switch is mounted in the lower latch
hook. They are activated by the latch heads on the door.
When the door is opened, the switches interrupt the circuit
to all components except the oven lamps.
A cook cycle cannot take place until the door is firmly
closed thereby activating both switches.
MONITOR SWITCH
The monitor switch mounted on the upper latch hook is
activated (the contacts opened) by the latch
head
on the
door while the door is closed, refer to Figure 5. The
switch is intended to render the oven inoperative by means
of blowing the fuse when the contacts of the upper latch
switch fail to open when the door is opened.
Functions;
1. When the door is opened, the monitor switch contacts
close (to the ON condition) due to their being a
normally closed. At this time the upper latch switch is
in the OFF condition (contacts open) due to its being a
normally open contact switch.
2. As the door goes to a closed positron, the monitor
switch contacts are first opened and then the upper latch
switch contacts close. (In case of opening the door, each
of the two switches operate inversely.)
3. ,lf the door is opened and the upper latch switch con-
tacts fail to open, the fuse blows simultaneously with
the ciosrng of the monitor switch contacts.
CAUTION:
BEFORE REPLACING A BLOWN FUSE,
TEST THE UPPER LATCH SWITCH AND
MONITOR SWITCH FOR PROPER OPERA-
TION (REFER TO THE TEST PROCE-
DURE ON PAGE 33.)
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UPPER
r ,'
LATCH
I
I
I
/
t
/
I
I
I
1
I
I
LATCH ,/'
HOOK
1 LATCH
HEAD
LiPPER
LATCH
SWITCH
LOWER
LATCH
HOOK
LOWER
LATCH
SWITCH
Figure 5. Latch Switches and Monitor Switch
26