Zeroing filters on Beseler Dichro 45s head

[Mike Bates]

I was practically given a Beseler 45mxt with a Dichro 45s head. I'm cleaning and aligning it. This is the head with the analog dial filter controls.

The filter dials won't stay at zero, especially Cyan. Opening the top of the head you can see the filter plates moving vertically, each with a spring. Turning the filter dial to zero moves the filter up and stretches the spring a bit. It seems the springs pull the filters down slightly. When I turn the Cyan filter to zero and let go, it moves to about 4C. Watching the light, I can see a slight color shift when I turn the dial from the resting 4C position to 0C and hold it. Of course, once I let go it returns to about 4C.

The dichro filter plates are sandwiched in the head and there are three 5/16ths nuts holding the sandwich together. I tried tightening the nuts to provide more friction to hold against the springs. I might have helped a little, but I didn't want to over-tighten them, especially if that's not the solution.

Any ideas? Keep tightening the sandwich nuts?

 

[skeller]

The manual talks about this, and states that a being couple of units off does not need to be compensated for. It also gives a procedure for calibration starting on page 11.

You can find a PDF of the manual at: http://backglass.org/duncan/darkroom/beseler_dichro_45_head.pdf

Hope this helps.

Steve

 

[Mike Bates]

Thanks. My head isn't the computerized model, so I don't have the calibration controls described in the manual.

I suspect the problem is a mechanical one of old lubrication that has dried. I'm not sure I want to tackle disassembly as there look to be a lot of small parts just waiting to fly apart. I may simply live with it like it is.