Olympus OM-1 Repair Manual page 46

B-25
Do not attempt checking too frequently, since it may cause for strings for
curtains to come off the pulley.
FP-Contact:
The FP contact has to be switched in within 10 ms. prior to complete
opening of the first curtain. Thus, normally, the signal is received from
the mirror driving mechanism. In case of MDS, the signal notifying the
mirror rising is transmitted to the shutter which in turn makes the switch
work by 8439.
When the mirror rises, 8439 moves in the arrowed direction to switch the
EP contact on.
(8439)
X-Contact:
Since the X contact is to be switched IN immediately upon completion of
the first curtain opening, the switching action is carried out by the first
curtain cam and the first curtain brake.
In case of MDS, it is switched in by 8578 of the first curtain brake lever.
Immediately prior to completion of the first curtain opening, 8578 starts
rotating in the arrowed direction, thus effecting the brake. The X contact
is made effective immediately after completion of the first curtain opening.
The brake is kept effective until completion of the film advancement. In •
the meantime, the X contact is also kept effective.
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