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Omega
C760 Enlarger
Service Advisory |
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1.
Focus Mechanism Assembly |
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This issue
applies only to Omega C760 enlargers manufactured during the first two years of
production.
The early
C760 enlargers
used a focus mechanism incorporating polyurethane friction rollers.
The nature of this material provided compensation for any wear and maintained tension with no adjustment.
However, it was subsequently discovered that these rollers decompose with age, eventually crumbling and/or
liquefying.
The amount of use is not a factor. When the rollers deteriorate, the
enlarger becomes unusable as it can no longer be focused. Beginning in 1982, Omega fitted C760s with a
different design using solid rollers with adjustable spring tensioners,
so later enlargers will not have this problem.
Initially, the repair for
the early type was to replace the entire focus assembly with one of the later type, and the majority of early C760s have been upgraded in this
manner. However, not all owners were aware of this problem and some
enlargers have not yet been upgraded. A number of these are
appearing on the used equipment market. With the C760 now out of
production for several years, Omega is no longer able to supply
replacement focus assemblies. KHB Photografix can upgrade old
assemblies to the newer specification, but because this involves
fabrication of custom parts and machining of the old assembly, the
repair is somewhat costly and it's best to avoid C760s with this
problem. |
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2.
Elevation Drive Rollers and Brake Pad
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This issue potentially applies to all C760
enlargers.
The C760 elevation assembly uses
drive rollers
made from a type of rubberized plastic, press fitted to a splined
shaft. The fine elevation adjustment knobs are fitted to the ends
of this shaft. With age and use, these rollers can crack, at which
point the rollers no longer grip the splines and the adjustment knobs
turn loosely with no effect. This does not completely disable the
enlarger as the carriage can still be moved up and down the column in a
"lift and lock" fashion using
the larger inner knobs.
The
elevation brake pad was also manufactured of the same material and we
now find units with these pads cracked or missing altogether.
Because Omega is no longer able to supply
replacement parts, KHB Photografix has designed replacement rollers and
brake pads. Users with a little mechanical skill should be able to
install these replacements.
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3.
Condenser Lenses
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This issue
affects C760 condenser enlargers only.
While
the similar B-66 and C-67 condenser lamphouses used condenser lenses mounted in
metal frames, Omega switched to plastic frames for the C760. The
flexibility of the plastic frames can allow the two condenser surfaces
to contact and damage each other if the lamphouse is given a sufficient
jolt. In addition, the lower condenser lens is not secured in
place so that if the lamphouse is tilted or inverted as is likely to
happen during shipping, the lower lens will impact the upper lens
causing damage to the convex surface of both lenses. To avoid such
damage, the condenser lenses should always be removed from the
lamphouse when the unit is being transported.
Replacements
are available, but since they are relatively expensive, condenser lenses should be inspected carefully when appraising used C760
condenser enlargers. |
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