On 8/30/2011 4:43 AM, Chuck Norcutt wrote:
> ...
>
> And this from Clint Rumbo 10 years ago.
>
> -------------------------------------------------------------
> Date: Sat, 10 Feb 2001 11:15:31 -0600
> From: clintonr@xxxxxxxxxxxxxxxx
> Subject: Re: [OM] Update: Resetting an OM-PC
>
> "Magnets -- why is it always magnets...."
>
> No, the PC doesn't have a "reset" position.
>
> The PC has 3 electromagnets -- one to control the exposure time, one to
> control the aperture arm in program mode, and one to release the first
> curtain. Any of them can get "sticky" -- sounds to me like the last
> one, the first curtain release magnet, is sticky.
>
> The only long-term reliable solution is to have the camera disassembled
> and get this magnet assembly cleaned -- a full overhaul, of course.
Starting with the second version of the OM-10, and continuing through the OMPC,
the internal structure under the mirror
box was changed. The location of the magnets was changed so that it's pretty
easy to clean that magnet by removing the
bottom cover of the mirror box.
Clint again, on Mark's hardware site, "By far, the vast majority of "battery
drain" complaints on the PC/40 are due to a
sticky electromagnet -- trust me, they are. It's an easy fix -- pull of the
front edge of the mask below the mirror and
clean the surfaces between the magnet and armature _carefully_. Then replace
the plate w/contact cement. In normal
circumstances, good silver oxide batteries (use no substitutes!) _will_die_ in
6-12 months. If a dedicated flash is
used, battery life will decline substantially. Lithium or alkaline batteries
will die in a few weeks. Period, end of story."
> But you _might_ get it to break loose for a while by smacking the camera
> firmly against the palm of your hand. (Now, now, now -- it's a sturdy
> beast, a firm>>whack<< or two (or ten!) won't hurt it! Just don't
> leave a lens on it when you do!)
The electromagnets have smooth, mating surfaces. If they get oil, especially
old, sticky oil, on those surfaces, the
spring can be unable to pull them apart when the current shuts off. Any solvent
that cuts oil may be used. I like
alcohol or naphtha (lighter fluid). It's easy to see if they are stuck when the
bottom of the mirror box is pulled off.
Moose
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