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A manual dowser would have the plate attached to a handle that can be manually activated. Virtually all xenon lamphouses have a manual dowser.

The "changeover" is the electro-mechanical device that controls the "changeover dowser". Generally, the dowser blade itself is part of the projector, while the changeover can be provided optionally from various manufacturers.

Don't see too many fire dowsers (also called "fire shutters") on projectors anymore, with the advent of safety film and efforts to reduce costs. A lot of projectors don't even have them available. Our Simplex Studio lines still have fire dowsers that are activated by a spring-loaded governor assembly on the vertical shaft. The dowser blade itself is weighted so it drops into the light path when the projector goes below a certain speed. When running normally, the governor opens the dowser.

So that's Strong's terminologies (hope I got it right, Jim...). The dowser itself is whatever blocks the light, there are several types of dowsers and different ways to activate them. In today's automated operations, the changeover dowser is probably the most common one we have to deal with, so "changeover" and "dowser" have almost become interchangeable even though they refer to two different components.

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Pat

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The problem I have had with the Christies is the aperature changer. Although the machines were maintained spotlessly clean, the aperature plate would have to be "helped along" while it was changing.

As far as the arguement is concerned, who cares what it is called? The average monkey-brain does not know the difference anyway, and more often that not, they call it a "Flippy Thingys"

I call them "Change-over Dowsers" some people call the change-over dousers, dousers, Flippy Thingys, Zippers, and whatever else comes to mind. Although I do believe in correct terminology, I don't always use it, either.

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There are two styles of Christie change-overs for these machines.

The early style was a real pain...they never stayed locked open. Lord knows how many times they dropped during shows and never kept their adjustment.

Christie came out with an improved design that works quite well...basically it is some parts to upgrade/convert and improve the older design. The new upgrades are now standard equipment, and the parts are available in kit form so that you can conduct the upgrade/conversion on the older units. I forgot the kit part #, so ask Bevan Wright.

Every once in a while they will need adjustment, and the best that I can say is that it is all by feel, but quite simple. If the cable does not travel smooth in the tube, then make very small "tweeks" on the tube until the cable is on center...then it will work like a charm. The new style uses a set screw spring ball plunger assembly that locks the douser open. This might also need occasional adjustment. Basically, just enough engagement is needed to hold the douser open...too much engagement will impede operation. And when tightening the locking jamb nut...just barely tighten it...torquing is not necessary and can damage the locking ball plunger assembly.

I did encounter someone who gooped the entire assembly (including the tube and cable) down with everyones favorite Lubriplate. This is NOT NECESSARY AND ONLY MAKES A MESS!

Speaking of Lubriplate. I have to get the specifics, but it is a product of Detroit, and one use is as a lubricant in machining and lapping brass.....

The Christie's douser was completly removed. The holes are show here. (When the pictures was taken the belts were being changed)


We must be carefull aligning the Christie's douser hole with the universal bell crank where we've done a new appropiate hole. We've took the strip from a solder electrode.