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TURN THE CENTER FOCUSING SECTION of the bulb positioning control counterclock-
wise until a small black spot is projected onto the wall. It may be best to run this adjustment both directions
to permit positive identification of the spot.
LOOSEN THE TWO THUMB SCREWS, one on either side of the center focusing section,
just enough to permit manual movement of the complete assembly. The bulb positioning control will now
move around these two thumb screws, and as this control is shifted, the smooth shadow of the bulb electrode
can be seen ex t ending beyond the projected center hole in the reflector. The shadow of the electrode (black
spot) must be centered in the projected hole of the reflector (shaded, less dense dark area).
MOVE THE CONTROL SECTION around the two screws until the black spot is as round as
possible to project. It may be necessary to again turn the focus control to project a sharply defined black spot.
AFTER THE BLACK SPOT is as even around the outside as possible to project, and appears
centered in the shaded reflector center hole (Spot "A"), tighten the two large thumb screws to lock the position
of the mechanism. Turn the center focus control to obtain the brightest light with the best light distribution (Spot
"B") and continue to the defocused position (Spot "C") to verify that the bulb is centered in the reflector.
IF THE CENTER BRIGHT SPOT tracks off to the left, right, top, or bottom, it may be neces-
sary to reposition the front bulb support yoke to compensate. Loosen the set screw in the support casting and
reset the yoke as required. The hex nut may be used to lock the height of the yoke. Secure the yoke with the
set screw after the bulb tracks on a straight axis. Return the focus control to the desired Spot "B," and rotate
the spot focus control knob, located at the extreme front of the lens mechanism, to obtain the sharpest edge
possible on the projected spot.
THE SECOND METHOD of focusing the xenon bulb is to project the spot to the stage, and
working with the above lamphouse controls, adjust these controls to obtain a "hot spot" on the projected spot.
Center this "hot spot" on the projected light by moving the entire control section around the two thumb screws.
Once this "hot spot" is centered in the projected light, lock the control in position with the two thumb screws
and turn the center section to obtain a spot with an even distribution of light. Rotate the lens spot focus control
knob to obtain a sharp edge on the projected spot.
THESE ADJUSTMENTS should not be disturbed until after replacing or rotating the xenon
bulb. At that time, the procedure on obtaining a smooth, round black spot, or "hot spot," may have to be re-
peated. Replace the cover plate over the bulb positioning controls and tighten the (2) thumbscrews.
BECAUSE OF NORMAL BULB AGING, and manufacturing tolerances b etween individual
xenon bulbs, it may be necessary to operate different lamps at slightly higher or lower current settings to
achieve balanced, uniform light output when two or more spotlights are used in one installation. This entails
a slight current output adjustment at the xenon power supplies. See the power supply manual.
XG4/010
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