On Mon, 9 Oct 2000 02:09:08 EDT, Tim wrote:
>The following may help you diagnose your problem, especially if you know a
>bit about electronics!
>
>Background:
> I don't have the official OM1N schematic but assuming it is
>similar to the the OM2N in so far as the flash is concerned then the OM1N has
>two sets of sync switches one for FP and one for X. The FP switch circuit and
>coaxial flash connector is isolated by a commonly available 1N400(6?) series
>diode from the X sync circuit. The X/FP selector either connects the X and FP
>trigger switch contacts in series (X mode) or shorts one end of the FP switch
>to ground (FP mode) It ony operates on the coaxial connector ** unlike the
>OM1**.
I have a copy of an OM1 manual and, according to that, there is no
diode isolation circuit (unlike the OM2). There are two contacts in
series, the FP one "nearest" the socket and the X one to ground. In
the FP/X switch is a simple shorting switch that shorts the link
between the two contacts to ground when in FP position, and is open
when in X position. When the shutter is fired the FP contact closes
just before the first blind starts moving and remains closed
throughout the shutter operation. The X contact closes as soon as the
first blind is fully open.
In FP position, the flash contact shorts to ground as soon as the FP
contact closes and so an electronic flash fires too soon. When the
switch is open (X position) the circuit is made through the FP contact
but finally shorts to ground when the X contact closes. The manual
specifically mentions a fault condition of poor insulation across the
X contact so that the charge in the trigger circuit of the gun leaks
away in the few milliseconds between the closure of the FP contact and
the closure of the X contact.
Unfortunately it looks as this may be happening in your camera. I
would not have thought its repair would be too difficult, though.
Regards
John Gruffydd (Mold, Wales, UK)
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