3-3
3.4
Exciter Lamp Level Confirmation and Adjustment
The output voltage of the lamp power supply is factory-set to be between 9.5 and 10
volts. Lamp intensity has a direct relationship to the video signal voltage. The acceptable
range for the peak video signal voltage (of unobstructed light through the perf hole) is
between 2.7 and 5 volts (see figure in Section 3.3). Under normal circumstances, the lamp
power supply voltage will never need adjustment to achieve the acceptable video voltage
range. However, some combinations of individual lamp intensity and projector speed
may result in a video signal outside the 2.7 to 5 volt range. In that case, it may be
necessary to adjust the lamp power supply. See diagram for adjustment location (VR1).
Do not adjust voltage above 10 volts at output of power supply.
If the top of the video waveform is not reasonably flat (+/–1 division), check for dirt,
dust, or other obstruction to the light path, and clean (see Section 7).
[VR1]
Voltage Adjust
3.5
Film Path Alignment
The film path is aligned during manufacture and should not require adjustment during
installation. The procedure for confirming or adjusting the film path follows.
The flanged guide roller on the top tension arm (the spring loaded roller between the
sprocket and drum) is the only film guide with provision for lateral adjustment. The
specification for its position is based on nominal film position. The film should be guided
so that the inner edge of the film is 25.4mm (+0.1-0.1mm) from a machined reference
surface on the soundhead housing (19mm diameter unpainted spot between the sprocket
boss and the light pipe). The outer edge of the flange on the guide roller therefore should
measure 61.9mm from the reference surface. To adjust the position of the guide, the rear
panel of the soundhead, the flywheel, and the tension arm spring must be removed. See
the diagram below for the location of the two screws that control the position of the
roller. Before loosening the clamp screw, note the angular position of the spring arm with
respect to the tension arm on the front of the soundhead (return the arm to the same
angular relationship prior to tightening). The lateral adjustment screw can be turned
after the clamp screw is loosened. A quarter turn of the adjusting screw will move the
lateral guide roller approximately 0.1mm.
