We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
surprising to find, a neglected piece of mechanism that is not properly lubricated and will cause rapid wearing of the bearings and unnecessary friction and drag on the upper spindle of the upper magazine.
We will briefly explain the action of the takeup mechanism. At the start of the lower reel, the film roll is, of course, very small, and the reel rotates at a very high speed; very gradually it slows down as the film roll gets larger and larger. Now, in order to provide for this continuous change in speed, the takeup mechanism provides a slippage between the driving pulley and takeup spindle. There is provision for adjusting the discs to compensate for this slippage and turn the reel, without excessive tension, until it is full. The tension should be adjusted so that the rotation, when the reel is full, can be stopped by a slight touch of the finger on the rim of the reel.
CHECK FOR TENSION
However, there should be enough tension to diive the reel without danger of it stopping. Only house reels with large hubs should be used to keep down any extra tension on the film when it first starts to rewind.
The upper magazine spindle should be occasionally checked for tension. Every modern projector is equipped with some sort of device to supply tension on the upper magazine reel spindle to hold it in retard. There should be just enough tension on the spring that acts as a brake to keep it from “racing” after the machine is stopped and also provide even speed of the film as it leaves the reel down to the upper feed sprocket. Smooth operation of the upper reel is of paramount importance, so that there will be no jerky action when the reel is started and stopped.
Another source of film damage is firetrap rollers. Time and time again, we have checked the operation of these in theatres and found them not turning freely and full of dirt and pieces of film. If these rollers do not turn all the time, they will develop flat sp>ots and cause damage to the edges of the film. Use a short piece of film and run this through the rollers, cleaning out all accumulations of dirt and broken pieces of film; then place a few drops of oil on the screws that hold them in the housing, removing any surplus oil.
SCREWS MUST FIT TIGHTLY
In modern projectors the upper portion of the fire-trap roller casting is curved to fit the contour of the magazine body, making connection of the magazine to soundhead much better and more solid. Screws that hold this assembly should fit tightly, and magazines should be perfectly aligned so that the film from the top magazine travels in a straight line down through the projector mechanism; likewise, the lower magazine should be carefully aligned so that the film will enter straight onto the lower takeup reel and not ride sides of assembly. Modern brands of projectors have much larger (wider) magazines, so that there is no problem of slightly bent reel (should use good house reels) scraping the sides or door of the magazines.
Frequently check your upper feed sprocket and, if badly worn (undercut) , replace immediately, as it might cause tearing out of the sprocket holes in the film
and jerky pull-down action of the upper reel. Be sure to also check the “stripper” plates on the upper, lower and soundhead constant-speed sprockets and see that they just clear the face of the sprockets, in order to keep the film from winding around the sprocket in case it should come apart at any one of these sprockets.
TENSION SHOES FLATTEN FILM
The correct tension on gate and tension shoes is of paramount importance. First, the primai-y function of the tension shoes is to flatten out the film as it passes through the projector film gate, so that there will be no tendency for the film to move while it is projected on the screen, nor in-and-out focus condition. Now, if excessive tension is made on the film it will cause damage and rapid wearing of the intermittent sprocket.
To determine the proper degree of shoe tension that should be applied to film in various conditions to produce maximum screen results and minimum wear on film (after many long tests by manufacturers) the following tensions have been recommended by most leading engineers and manuf actui’ers : For new film, tests proved that a pressure sufficient to cause a film pull tension of eight ounces would produce best results. Similar tests were made with prints that had passed the first-run stage, and it was found that a tension of 12 ounces was most desirable. Very badly buckled film often required 20 to 24 ounces of tension to keep it steady on the screen. But in no case use more than necessary film shoe tension to hold the film firm.
Many of the modern projectors have a screw adjustment, with numbers on small plate for obtaining the correct tension, but with old-type mechanisms it is necessary to bend the springs slightly by hand to obtain necessary tensions. This is not always an easy task with some types of gates, as it is necessary to remove some parts to do so, so in this case it is best to try to set the tension as nearly correct as possible for new and old prints.
The importance of furnishing, in their projectors, a variable shoe tension device capable of operation while the projector is running has been recognized by most leading manufactimers of projection machines.
Remember that film track shoes are subject to very heavy wear, and as soon as there is appreciable wear they should be removed and replaced with new ones, otherwise they might cause some scratching and will cause out-of-focus effect, more so, if one side should wear faster than the other — and this often happens!
ADJUSTING IDLER SHOES
On older types of mechanisms, particularly on standard Simplex mechanisms, one should use extreme care in adjusting the intermittent sprocket idler shoes. These shoes are part of a cradle (cradle shoe) held in a steel apron attached to the film gate, or door. This cradle can be formed, if necessary, so that the shoes fit perfectly against the film and intermittent sprocket. They should be kept free of film particles and dirt, and there should be just enough tension on the flat cradle spring to hold the shoes snugly against the film. If set too far away from the face of the sprocket.
Continued on following page
THEHTRG SERUIIE CREIRS
ISO POIRTS
RCA’S COMPREHENSIVE SERVICE CHECKLIST INCLUDES:
El SPEAKERS El SOUNDHEADS El AMPLIFIERS El POWER SUPPLIES El SOUND CONTROLS El MOTORS
El FREQUENCY RESPONSE El SOUND QUALITY ANALYSIS
The RCA Theatre Service Program is planned to be thorough . . . planned to be complete . . . planned to produce superior performance. Thousands of exhibitors enjoy this better service program —why don’t you?
TECHNICAL PRODUCTS SERVICE
RCA SERVICE COMPANY
A Division of Radio Corporation of America Camden 8, N. J.
BOXOFFICE :: November 5, 1962
17