m a g n e t
LEADS
Figure 96
Figure 97
SHUTTER-COCKING
LEVER ENGAGES
OPENING-BLADE
DRIVING LEVER
HERE
TRIGGER-SWITCH
LEAD ------------
TRIGGER-
SWITCH
1 ECCENTRIC
g r o u n d
]
.LEAD
Figure 98
Simulate the release action by pulling
down the opening-blade driving lever,
Fig. 96. As the opening-blade set moves
down, it uncovers the aperture. The
shutter-cocking lever then latches and
holds the opening-blade driving lever,
Fig. 96.
Next disengage the closing-blade latch
and pull down the closing-blade driving
lever. When the closing-blade driving
lever reaches the position shown in Fig.
97, it strikes the latch on top of the
opening-blade driving lever.
Disengaging the latch frees the opening-
blade driving lever. The return spring then
drives the opening-blade driving lever in a
counterclockwise direction. And the open
ing blade returns to the raised position,
covering the focal-plane aperture.
On reassembly, leave the shutter dry —
no lubrication. Remember, oil quickly
works its way to the shutter blades and to
the electromagnet. Also, before you in
stall the shutter on the mirror cage, you
m ight double-check the operation of the
trigger switch. Connect an ohmmeter
between the black-wire terminal, Fig. 81,
and a metal portion of the shutter. W ith
the shutter cocked, you should read
direct continuity. You should read infinite
resistance w ith the shutter released.
TIM IN G CIRCUIT FOR ADJUSTING
THE SEIKO SHUTTER
Earlier, we mentioned that you can
build a timing circuit for adjusting the trig
ger switch. Just connect the timing cir-
'c u it to the shutter's lead wires as shown
Figure 99
in Fig. 98. There's only one problem —
you disconnect the shutter leads to
remove the shutter.
If you're also removing the flex circuit,
you can leave the shutter leads connected
to the shutter-terminal board, Fig. 98.
Disconnect the other ends of the wires
from the flex. Otherwise, you'll have to
temporarily solder wires to the shutter-
terminal board.
Then connect the test-circuit leads to
the shutter leads, Fig. 99. The magnet
leads connect to the tw o wires going to
the electromagnet — red and brown.
Now the test circuit supplies the power to
hold open the shutter. The trigger-switch
lead connects to the wire going to the
trigger switch, and the ground lead con
nects to any metal part of the shutter.
The trigger-switch lead and the ground
lead now connect across the shutter's
trigger switch. Remember, the trigger-
switch eccentric pin is a ground connec
tion. In some Seiko shutters, however,
you'll find that the eccentric pin does not
connect to ground. Instead, a separate
wire goes to the eccentric pin. In that
case, connect the trigger-switch lead of
the test circuit to one of the wires going
to the trigger switch; connect the ground
lead to the second trigger-switch wire.
W hen you now release the shutter, the
trigger switch tells the timing circuit to
start timing the exposure. You can then
use a shutter-speed tester to measure the
exposure time. The shutter should deliver
1/1000 second w ith the timing circuit
connected. If not, simply adjust the
trigger-switch eccentric, Fig. 98.
The timing circuit in the test box
