Changeovers.....How to do it
(Editor: The following text from an old 35mm
Standard exchange prints all have leader at the beginning of the reel with numerals marked on the turn at every foot with two exceptions. The twelfth foot is marked "Start" instead of "12" and "1" and "2" are not printed so that the first number next to the picture is "3".
The following instructions should be put into operation before a show is run so that the operator will become proficient in making changeovers. Thread machine No. 1 (left machine is No. 1, right machine No. 2) with a reel from a feature. Thread machine No.2 so that "8" on the leader is close to the film gate. Remember the changeover cues take the form of black dots in the upper right hand corner of the screen.
When ½" layer of film is left on the upper reel of machine N0. 1 (approximately one minute running time) take a position between the two projectors in such a manner that with the left hand on the switches of machine No. 1, the switches of machine No.2 can be manipulated with the right hand. In this position the picture must be seen through the observation port.When the first (motor) cue appears, approximately 8½ seconds before the end of the reel, with the right hand throw motor switch of machine No. 2 "On" Immediately thereafter, put the right hand on the lamp switch. Place the left hand on the lamp switch of projector No. 1. Seven seconds after the first cue, the second (changeover) cue will appear. At that moment, simultaneously throw lamp switch of machine No. 2 "On" and lamp switch of machine No. 1 "Off" and continue over with the left hand to the amplifier and throw changeover switch to the right to "2". Be instantly ready to turn amplifier volume control up or down and to frame picture in the event either is necessary.
As soon as the film in projector No. 1 has run out, stop machine, thread same with another reel and follow the above procedure on the next changeover. The footage number threaded in the aperture depends on the acceleration of the motor and as this acceleration varies with different motors, the two projectors may have to be threaded with different numbers. However, after the number for each machine has been determined, it should be marked on the threading diagram on the inside of the projector door for the benefit of operators not familiar with the equipment.
Numbers flashing on the screen after the changeover indicates that less leader must be used when threading. For example, if "3" should flash on the screen, thread the machine the next time with ''7'' at the aperture gate (bearing in mind that the machine was originally threaded with "8" at the gate.)if just the opposite results and the changeover is made in the middle of a sentence or the continuity of the picture is interrupted, more leader must be used when threading. Thread projector with "9" at the aperture and make a changeover. It the above condition persists, try "10" and so on until a perfect changeover is made.
It is imperative that the clutch mechanisms on the lower magazines be properly adjusted at all times. The take-up belts also should not be allowed to become so loose that they slip on the take-up pulleys. During a changeover, the operator cannot always watch to see that the lower reel is taking up properly.