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DOOR LOCK OPERATION
MFS25 and MFS35 models:
There are two switches, two direct current
(d.c.) solenoids and mechanical interlatches
involved in closing and locking the door.
As the door is closed:
At the handle side of the door, a tongue on
the door handle lever enters the door lock
housing and straddles a roller pin as the door
closes. As this door lever tongue moves over
the door lock roller pin it moves in and pivots
around the door roller pin, providing a
"toggle" action that pulls the door fully
closed, and at the same time causes the tip of
the door handle tongue to lift a flat "leaf"
spring clear of the door handle lock arm. This
lock arm is moved by the door lock solenoid
to lock the door when the machine is
11
in
cycle". Additionally, an alignment pin on the
door lines up with and enter a socket (hole)
just below the door lock roller pin. As this
pin enters the socket, the end presses the
actuator leaf on the door closed switch
(SQ2). SQ2 is in series with the current
overload protectors on the contactors and
the thermal overload circuits in the motors. If
these series circuits are closed, there is
continuity from J4.1 on the control board to
J4.6 on the control board, supplying current
for RL20 on the control board. Refer to the
wiring diagram of the machine for help in
understanding the door closed switch circuit.
At the start of a cycle, RL8 on the control
board closes and supplies current to the
bridge rectifier GU2, which converts the 208-
240 volts AC to DC voltage and powers the
door lock solenoid and the bimetal in the
door lock assembly.
With current on the door lock solenoid, the
plunger pulls into the solenoid, forcing the
lock arm under the door handle tongue,
locking the door securely and activating the
door lock microswitch (S01). Atthe same
time, the blocking arm is pushed into posi-
tion behind the plunger of the door lock
solenoid by the bimetal, preventing the door
from unlocking in the case of component
failure or power loss. The bimetal will allow
the door to be opened after a delay of ap-
proximately one minute if the power is not
restored to the door lock circuit.
At the end of the cycle, RL 18 is switched off
and RL 16 is switched on. RL 16 supplies 208-
240 volts AC to bridge rectifier GU 1, which
supplies DC current to the door unlock
solenoid, forcing the blocking arm upward.
With the blocking arm upward, the plunger of
the door lock solenoid retracts, unlocking the
door.
Note:
At the end of the cycle, the display on
the control board shows "Unload Now" and
DC current is applied to the door unlock
solenoid until both SOT and SQ2 are open.
With the door both unlocked and opened the
display changes to "Select
Process'~
MFS50 models:
The operation of the door lock is essentially
the same as the MFS25 and MFS35 except
the MFS50 (and larger) model does not have
a bimetal in the door lock assembly. When
the machine is started, a spring forces the
blocking arm downward, preventing the
plunger of the door lock solenoid from
retracting (unlocking the door) in the case of
a power failure.
At the end of the cycle, the door unlock
solenoid is powered and forces the blocking
arm upward, allowing the door lock plunger
to retract and unlocks the door.
MFS75/80-125 models, as the door is closed:
At the handle side of the door, a tongue on
the door handle lever enters the door lock
housing and rotates the locking cam down-
ward as the door closes. As this door lever
moves downward the door lever roller moves
against a nylon block inside the door lock
assembly, pulling the door gasket tight
against the shell front lip and fully closes the
door. The door is held in a closed position as
the roller drops into a notch in the nylon
block. With the locking cam in the downward
position S01 is closed. Additionally, an
alignment pin on the door lines up with and
enters a socket (hole) in a nylon block
16009607
©1999 Mayt
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Section 2. Service Procedures
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