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2-415
Step 3
Step 2
Power
switch
Shutter actuator lever operates the power SW and B(bulb) SW.
B SW
turns
''on'' when
the lever
is in its original position.
With the shutter
dial set at B,
B SW
close a short circuit from
the source
to the capacitor,
C1.
(Refer to Fig. 2-21)
The power
SW turns
"'on'"' before
the shutter mechanism
starts
ope-
ration in order to supply a current
to the circuit beforehand.
Actuator
pin on the diaphragm
checker
hook keeps the power
SW
"'on",
even when
the actuator
lever returns
to the original position (taking the finger off
the shutter button) during low-speed
exposure.
The safety lever which
changes
its direction depending
on the position
of the diaphragm
charge
coupler lever,
shifts the engagement
between
the
shutter actuator
lever and hook to ''on" or "'off"',
as shown
in Fig.2:21.
SHUTTER ACTUATOR
LEVER
SHUTTER
ACTUATOR
HOOK
SAFETY LEVER
POSITION b
DIA. CHARGE
RELEASED,
COUPLER LEVER
;
pale
Fig.2=21
POSITION,
COCKED
SHUTTER
CURTAIN BOUNCE
PREVENTION
Unlike the other types of Pentax,
both the
lst and 2nd curtains
have
their respective
bounce
prevention
system
in this Pentax
6x7.
Asa
bounce
prevention,
the friction disk absorbs
the kinetic energy
of the
shutter
curtains
that has passed
over
the picture frame.
The prevention
system
starts
its operation (the curtain
speed
starts
decreasing)
shortly
before the curtain
edger reaches
the end of the picture frame.
This
system
also determines
the original position of the respective
curtain.
The
system mainly consists
of friction disks,
ratchets,
damper
gears andarms.
The
ratchet makes
the damper
arm
free from
the
fri-
ction disk when the arms
are re-set.
—
Although the operational principle of the bounce prevention system
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