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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