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688 HANDBOOK OF PROJECTION FOR
bracket. Be sure you tighten both these screws after raising shaft into place. Next place shutter on shaft with hub out as shown in P-3, with screw 739, P-6, in V groove in shaft.
Should travel ghost (streaks up and down from letters of titles, or flashes of white up and down from white object in pictures) develop at any time, it may be eliminated by resetting the shutter. Loosen one of the screws 790 and slack off on the other one until shutter ran be slipped by applying some pressure. If streaks are up hold flywheel stationary and revolve the top of the shutter away from you slightly, and, with a title having white letters on an opaque background, try it. If the streaks are down, pull top of shutter towards you. Keep slipping shutter slightly and trying until streaks disappear. Then tighten up screws 790. When travel ghost develops., first be sure screw 739, P-6, is set up tight. To set a new shutter, proceed as follows : Place shutter on shaft as shown in P-6, with hub towards end of shaft. Set screw 739, P-6, in groove and tighten it. Loosen screws 790, P-6, so that shutter revolves freely on inner hub. Open gate and turn flywheel forward until intermittent sprocket is just at point of moving. Set shutter as shown in P-6 and tighten one of 790 slightly. Then proceed as directed for travel ghost. For very short focal length lenses the Nicholas Power Company will supply a special shutter on application. Their two-blade shutter should always be used on 60-cycle A. C. The blade with stamp B, P-6, on it is the master blade, and the only one to be considered at all in setting the shutter.
Travel ghost may be caused by (a) screw 739, P-6, being loose, (b) Collars 638, P-4, not set up snugly against bearing, thus allowing end play in shutter shaft, (c) Gear 680, P-3, loose on its shaft, (d) Gear 633, P-4, loose on its shaft, (e) Badly worn gears. Any one of these things, or all combined, may cause travel ghost. Screws clamping shutter blade in flanges of hub being loose might also be responsible for it.
TRAVEL GHOST may also be caused by master blade being too narrow, in which case it may be removed by moving the shutter to a position where it will cut the light beam at a point where it has less diameter, if there is such a point, or by making the blade itself wider.
NOTICE. — On mechanisms equipped with adjustable shutter bracket Knob A-figure 249 should be turned until the Fork D is located centrally between bearings C and E. Having done this you may make the roughly correct adjustment of the shutter as before directed, completing the final adjustment by turning Knob A, figure 249 in the required direction after the projector is running.