Sharp R-200BK Service Manual page 9

SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. LIGHT UP DIAL ON.
C/T FUSE
A3
CONTROL UNIT
120V AC
60 Hz
DOOR OPEN MECHANISM
The door is opened by pulling the door, refer to the Figure
D-1.
Latch Heads
Secondary
Door
Interlock
Switch
Figure D-1. Door Open Mechanism
DOOR SENSING AND SECONDARY INTERLOCK
SWITCHES
The secondary interlock switch is mounted in the lower
position of the latch hook and the door sensing switch in the
primary interlock system is mounted in the upper position of
the latch hook. They are activated by the latch heads on the
door. When the door is opened, the switches interrupt the
power to all high voltage components. A cook cycle cannot
take place until the door is firmly closed thereby activating
both interlock switches. The primary interlock system con-
sists of the door sensing switch and primary interlock relay
located on the control circuit board.
MAGNETRON
THERMAL CUT-OUT
COM.
(RY-1)
PRIMARY
INTERLOCK
RELAY
A1 A3
DOOR
SENSING
SWITCH
SECONDARY
INTERLOCK
SWITCH
Figure O-2. Oven Schematic-Cooking Condition
DESCRIPTION AND FUNCTION OF COMPONENTS
Latch Hook
Door
Sensing
Switch
Monitor
Switch
N.O.
OL TTM
FM
MONITOR
SWITCH
TURN-
OVEN
FAN
LAMP TABLE
MOTOR
MOTOR
MONITOR SWITCH
The monitor switch is activated (the contacts opened) by the
latch head on the door while the door is closed. The switch
is intended to render the oven inoperative, by means of
blowing the C/T fuse, when the contacts of the primary
interlock relay (RY1) and secondary interlock 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 normally
closed. At this time the primary interlock relay (RY1) and
secondary interlock switch are in the OFF condition
(contacts open) due to its being normally open contact
switches.
2. As the door goes to a closed position, the monitor switch
contacts are first opened and then the door sensing
switch and secondary interlock switch contacts close.
3. If the door is opened, and the primary interlock relay
(RY1) and the secondary interlock switch contact fail to
open, the C/T fuse blows simultaneously with closing of
the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN C/T FUSE,
TEST THE DOOR SENSING SWITCH, PRI-
MARY INTERLOCK RELAY (RY1), SECOND-
ARY INTERLOCK SWITCH AND MONITOR
SWITCH FOR PROPER OPERATION. (RE-
FER TO CHAPTER "TEST PROCEDURE").
NOTE: C/T FUSE AND MONITOR SWITCH ARE
REPLACED AS AN ASSEMBLY
7
R-200BK
R-200BW
POWER
TRANSFORMER
CAPACITOR
0.72 F
RECTIFIER
MAGNETRON