Electrical Help with Omega 5x7 Enlarger
I'd appreciate some thoughts on some electrical components for my enlarger, as I'm only qualified as dangerous in this area. Back in the late 60's I bought a new Omega E-6XL enlarger (5x7) that included the Power Lift and Power Focus accessories, all long discontinued. The Power Focus device has abruptly become so sluggish as to be useless. It was necessary for making large prints with the head raised very high - out of reach when focusing with a grain focuser. The location of the fault is not obvious, whether it's in the motor (not likely because of the sudden nature of the failure) or in the controller's buttons for coarse/fine adjustments. Then there's the gizmo (transformer?) mounted on the baseboard next to the column, inline between the controller and the motor, that may be the problem source. The enlarger is still in fine condition otherwise, so if there's no hope of salvaging the Power Focus device I'll just figure out a means of operating the manual focus knob, similar to that sold by KHB Photografix (at a price that exceeds today's market value of the enlarger).
Last edited by silveror0; 06-25-2011 at 04:10 PM. Click to view previous post history.
The sluggish Power Focus might be because of gummed up lubrication on rails or gears or whatever the mechanism. I'm not familiar at all with the enlarger, but the fault might not be electrical at all.
I don’t think that sudden failure precludes the motor as the source of trouble. If the motor is of the graphite brush/commutator variety, the brushes might have worn to the point of loosing electrical contact with the commutator.
If that’s the case, simply replacing the brushes and cleaning any graphite deposits from the commutator—especially the gaps between the conductive segments might restore operation.
If the motor needs replacing, then you should be able to find one of the correct size and specifications. Simmon Brothers or Berkey Marketing Companies, whichever was the owner at the time of your enlarger’s manufacture, almost certainly didn’t make electric motors, but bought them from a vendor just as it did for almost all of the inner components.
The focusing control is likely easily analyzed and understood by someone with experience with electrical devices. I’d expect that the heart of a fine focusing control as you’ve described it was some sort of variable resistor to slow the motor so as to “creep” the focus slowly without overshooting.
That or a reduction drive might have been used. I haven’t specific knowledge of the system used for the electrically-driven fine focus so I’m necessarily speculating on how the fine focus is driven on this machine.
Enlisting the aid of a competent electrical or electronics technician might make the source and particular cause of the fault readily apparent. At least in that way you wouldn’t be aimlessly speculating as to the cause of the problem.
In most cases, when such devices are opened and investigated it turns out that all the components are off-the-shelf industrial products that in most cases can still be obtained provided one knows where to look.
Usually, the only proprietary parts (custom fabricated for one particular product) are circuit boards and sometimes integrated circuits (but a custom IC isn’t likely for a simple motor controller).
Post #2 makes a good point. Make sure that there isn’t gummed lubricant on the rails as that could turn any lubricant into varnish after 40 years or more. Dried lubricant might be inside some part of the unit causing the problem. You won’t know until you investigate.
This might take some research and possibly assistance from someone knowledgeable in electrical matters.
It almost certainly can be made to work again.
Ian C, thanks for the info and a ray of hope. I'll open things up and have a look.