The OM-1/1n and 2/2n both use CdS cells to control the meter needles. Being
photo-resistive (rather than photo-voltaic, for example selinium cells),
they are much less prone to "aging". But I'm sure it's possible for them to
"drift" over time, though we haven't seen this to be a problem.
Basically, the meter in the OM1's and 2's is a simple galvanometer circuit
with fixed adjusting/compensating resistors. All the other inputs are
mechanical, such as the ASA and aperture, and (on the 1's) the shutter
speed. This is why they're so reliable -- no VR's to wear out like so many
other cameras of this era.
When things go bad, they usually just die -- coil springs inside the meter
(galvanometer) break, windings in the glavo's coil open, that sort of
thing. Occasionally the lead going to the galvo breaks (it flexes every
time the galvo moves, as with aperture movement), or a coil spring will
"loop" over a counter weight inside the glavo. These problems and almost
everything else are repairable.
John Hudson wrote:
> Has anyone experienced the meter in their OM2n seemingly wear out over
> the passage of time such that the camera's meter readings are
> consistently over exposing their photos? By "wearing out" I am referring
> to what happens to a Western Master IV or V meter which does not have a
> battery but where the meter's light cell loses its potency over time and
> at the end of the day, actually after many years, is simply inoperative.
>
> John Hudson
>
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