Olympus OM-1 Repair Manual page 45

B-24
(16) Flash Synchronization Circuit:
In a single reflex, normally it takes the mechanism wherein the X contact
is always kept ON and/or it is switched on again when the film is advanced.
This causes an explosion at the time of the film advance. Therefore,
normally the X contact piece is made movable to prevent it. However,
because it means unstable positioning of the contact piece, FP and X are
connected parallelly in case of MDS.
To check the insulation resistance of the contact piece, in case of X
contact, set the shutter dial at 1/1 and release it. While the 1/1 governor
is in operation, move the film advance lever for about half a stroke.
See if the needle of the Insulation Resistance Meter) shows over 30nn.
A check can then be carried out.
In case of FP turned ON and X being OFF, when the film advance lever
is moved for a full stroke, curtains will make their runs and will return
to the normal position. A check can then be carried out.
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