Door Lock Function - Electrolux W4400H Service Manual

150
Door lock function
The door is locked by means of an electrome-
2
chanical, bistable locking device. The lock has
two stable states; one when the lock pin which
locks the door handle is extended (the door
lock is locked), the other when the lock pin is re-
tracted (the lock is unlocked). This means that,
in the event of a loss of power to the machine,
the lock will remain in the same state as before
the loss of power.
When the locking arm has closed the door, the
switch cam is actuated and it closes micros-
witch S. The program control unit monitors the
status of S, and when S closes, the program
control unit can give the command for door
closing.
The door lock control unit checks that there is
no water in the drum and that the drum is at a
standstill. After that the door lock control unit
locks the door lock by activating the solenoid, to
make the lock pin enter a slot in the lock plate.
When the lock pin is fully home in this slot, swit-
ches S4A and S4B both close. Only now, when
S, S4A and S4B are all closed, will the outputs
on the I/O boards which control the machine's
functions be energised, and the wash program
can begin.
When the program control unit requests that
the door be unlocked, the door lock control
unit checks that there is no water in the drum
and that the drum is not rotating. After that the
solenoid is activated, now with polarity reversed,
to make the lock pin disengage and to allow the
door to be opened.
Door and door lock
2
I/O board 1
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Phase to I/O outputs
Closed door status
indication
Neutral to I/O outputs
4129