Meter resistance should be around 1.35K. If the meter is mounted in the
plastic housing, there is a second ground connection that can fail which is
under the meter, where the ground strap is clamped under the gear plate. If
meter is off 2 stops at all light levels, use eccentric on top of meter
housing to adjust it out. If eccentric doesn't give you enough swing, you'd
have to changed string timing on the bottom of the meter.
John Hermanson
Camtech Photo Services, Inc.
21 South Lane,
Huntington, NY, 11743-4714,
631-424-2121, www.zuiko.com
_________________________________
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Monday, October 04, 2004 12:47 AM
Subject: [OM] Re: Troubles with OM1n meter
> Ing. Radovan Faltus wrote:
>
>>Hi fellows, I've problem with exposure meter of my OM-1n, when i bought
>>it, it didn't measure correctly, so resoldered resistors and reassemled
>>main switch and it went OK.
>>But now i see the same problem again. The needle shows 2 stops less than
>>it should (results in overexposure)
>>
> You have the right, healthy battery?
>
>>and it moves even when the light is constant which makes me think about
>>wrong connection somewhere, but couldn't find anything except one junction
>>which i didn't check: meter coil - ground.
>>Can anybody tell me what is coil resistance to check this last place?
>>How to solve it if the problem was there?
>>
> Here are some pieces of past posts on the subject:
>
> From Clint,
>
> If you have a newer style meter (where the meter frame is separate from
> the eyepiece, mostly on 1n's), check the ground -- touch from the metal
> frame of the meter to the body and see if the meter doesn't jump up. If
> so, lift out the meter/frame assy and clean the foil grounding strip
> w/acetone to remove the glue. Also, you might want to scrape away any
> paint from the body around the screw hole where the foil strip is held.
>
> On others, wick off the solder on the circuit board and reapply -- and
> while you're at it, gently wiggle the resistors, sometimes they'll crack
> so that you can't tell until they're moved.
> --------------------------------------------------------------------------
> From Mark,
> You can easily check the meter resistance. Desolder the blue wire from
> the
> circuit board and measure the resistance between it and the case. I
> believe
> it should be about 1.5K. If it isn't then follow Clint's instructions for
> cleaning the ground contact. You should also check that the brown wire
> gives no resistence between where it connects on the circuit board and the
> battery tab.
> --------------------------------------------------------------------------
> From Clint,
> Only by removing the top cover. On the earlier versions of the OM-1, the
> meter,
> eyepiece and meter circuit were held in a frame that went from one side of
> the
> prism to the other. On the later versions OM-1 (as well as the 1n) the
> meter,
> eyepiece and meter circuit could be removed independently of one another.
> A
> common problem with this style was that the meter (being in a plastic
> frame) was
> grounded by a thin foil strip which was glued in place on the underside of
> the
> frame. Occasionally the glue would seep between the foil and body, or the
> body
> would be painted where the foil strip was placed, so that the ground would
> be poor
> to non-existant. Cleaning and scraping solved the problem.
> --------------------------------------------------------------------------
> From John,
> Meter coil could be open or meter ground loose. If it is the type of
> movement mounted in a plastic housing, tighten the screw at the edge of
> the
> housing at the back of the camera. If there is a thin metal strap running
> from the back edge of the metal meter (old style) tighten the screw over
> each end of the strap. Don't tighten the screw going through the brass
> meter shell too much as it goes into plastic and it is becoming more
> common
> for the plastic to crack or crumble into dust.
>
> Moose
>
>>
>>Thanks,
>>Radek
>>
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>>
>
>
>
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