Boxoffice (Oct-Dec 1963)

CARE OF SCREEN A MUST' Continued from preceding page the screen, brushing downward slowly to the bottom each time. Don’t push hard with the brush when cleaning as it might cause a dent in the screen. Use a brush with a long handle. After you have finished your cleaning job, wrap the brush up with a clean cloth and keep it where no one will use it for some other purpose. Supply dealers keep brushes in stock but, if not, send to the manufacturer. Sometimes it is a good idea, when cleaning the back of a screen, to use a vacuum cleaner to draw out the dust from the perforations, but this must be done very, very carefully so as not to damage the screen surface. Never use a vacuum cleaner on the front side of the screen, only a screen brush. We have received many letters asking how to remove candy or other kinds of spots from a screen. Frankly, there is no way to remove a bad spot except to have the screen refinished. If you try to paint a spot with screen paint, you make matters worse and have a “sun” spot where you have used screen paint. MORE VOLUME REQUIRED Why should perforations be kept open? Some may think that partial plugging of perforations will do little to sound output but, if they are not kept cleaned, the sound, in time, will become “muffled” and it will require more volume. In most high-quality sound screens the perforations approximate 10 per cent of the total area of the screen surface. Perforations have been made standard in distance by most leading screen manufacturers. The reason for this is to cut down light loss and still not cut down sound output and quality of sound reproduction. We find that most modem screens consist of a plastic material, some have a cloth backing to reinforce the material and make it much stronger. However, most manufacturers use a very high-grade plastic material that will give long service. And the very finest material is used for coating that will retain its reflective powers a long time. However, any type of screen finish will gradually deteriorate with age and should be replaced with new or refinished surface after four or five years. TRAVELER CURTAIN PROTECTS FROM DUST We are strong for a traveler curtain that can be closed when the theatre is not in operation and will help to keep dust off the screen surface. Considerable dust settles on the surface when the auditorium is being cleaned and sometimes this dust is not cleaned off for months. It takes only about an hom to clean most screens and one should take pride enough in his screen presentation to do this at least once a month. It is not wise to accept any statement from a high-pressure salesman that his particular screen could be cleaned and always retain its same high reflective powers. Cleaning frequently with a good camel-hair brush will help, of course, but as the screen ages it will lose some of its reflective power with each successive cleaning. We know, from long experience and maintenance of theatre cleaning. Tests with precision meters have proved this conclusively. Therefore, good screen maintenance is a “must” in any theatre if one expects better projection. In conclusion, a clean, bright picture, such as every theatre owner desires to bring before his patrons, requires a combination of projectors, lenses, arc lamps, rectifiers or generator, all in good operating condition — and a new screen. Everyone conversant with motion pic tures knows that the screen plays a most appreciable part in improving picture definition, and bringing out the highlights and beautiful colors in color photography. So, while buying a new screen is more important than ever today, buying the right kind of screen surface and type is equally important. Don’t just buy a screen — or just don’t pick your screen on price alone. Look for the fabrics that will give long service and will not puncture easily. The right kind of plastic material will give longer service. And buy one that best complements the projection angles and auditorium width and will have the least fadeaway at the sides. The finish will depend on the type of arc lamps and the width of the auditorium. Again, keep the perforations in your screen free of dust; clogged perforations will cut down sound transmission and the quality of sound output. Clogged perforations will many times muffle the sound — especially so, on high frequencies. Screen manufacturers have standardized on hole size and distance spacing, so, if you buy a well-known make of screen you will be assured of good sound transmission if you do your part in keeping your screen clean. TRUE ECONOMY IN NEW SCREEN WHEN NEEDED We realize that the average theatre owner wants to use his equipment just as long as he possibly can, and we have no quarrel with him for it, for we are just as much a believer in true economy as the next fellow. Note that we say true economy. When your screen sprouts a thick crop of fuzz, it’s high time to contact your equipment dealer and get a new one. Don’t put up with inferior projection because of spending a few dollars. Keep your patrons happy with better projection and high-quality sound reproduction. It pays off at the boxoffice! General Maintenance of Xenon Projection Lamps First, let us present a few instructions on handling the xenon bulb. The xenon bulb, when outside of the lamphouse, must be encased in its plastic protective shell. The projectionist should always wear the protective shield when opening the lamphouse or when handling the bulb. Play safe and avoid accidents. The bulb should always be inserted into the lamphouse while still encased in its protective shell. The shell can be removed when all the necessary cable connections have been made. Keep this in mind: When removing the bulb from the lamphouse it should always be encased in the shell and then all cable connections removed. Don’t touch the glass envelope of the bulb; fingerprints will burn in the glass and dull the bulb, thereby slightly cutting down light output. If fingerprints are made the bulb should be cleaned with methyl alcohol. Use a soft, lintless cloth for cleaning. CAUTION: Never open the lamphouse door when the bulb is in operation. Wait at least ten or 15 minutes for bulb to cool. Keep interior of the lamphouse clean and all the electrical connections tight and clean. You will obtain longer service from your bulb, if you will follow our instructions. Be sure to dispose of unusable bulbs, immediately, in the following manner: Wrap the bulb with several layers of canvas or very heavy cloth and smash it with a hammer before depositing in a refuse container. Always keep a supply of extra bulbs on hand and in a safe place where no one will handle them until needed. Always encase the bulb in its protective cover when cleaning the interior of the lamphouse. OPERATION TIPS As a xenon bulb ages, its light output, of course, will diminish. The slow aging of a xenon bulb in one projection lamp will cause an imbalance of screen light at projector changeovers. Now, to maintain screen light balance, increase the current of the lamp giving low light output; or you can decrease current of the lamp giving high light output; or adjust the current equally in both lamps. This should be carefully watched and the check made while running both projectors without any film. Checking the light output should be done at least once a month and as the bulbs age, this check should be made more frequently. When placing the plastic protective shell on the xenon bulb make sure that the plastic case fits over the lip on the anode and cathode base. Only the anode and cathode base should protrude from the plastic shell. Adjust the rectifier dial switches and internal line taps to obtain 63 amperes as indicated on ammeter, when bulbs are new. The xenon lamp requires very little maintenance to keep it in good working order. The same care, with the extra precaution in handling, should be given as with arc lamps. If you remove the reflectors for cleaning or any other purpose, check to see that they are again adjusted for maximum light output after reinstalling. Cleaning should be done as outlined in the writer’s Service Manual as special procedure should be adhered to so as not to damage the surface of the reflector. Imbalance of screen light at projector changeover. Remedy: Adjust as per instructions above. Lamp fails to light. Check for defective bulb. (Buzzing sound is heard when ignition button is pushed.) Replace with new lamp. It may be defective quench sparkgap (no buzzing sound heard when ignition button is pushed). Replace this part as it has become defective and bulb will not light, of course. — Wesley Trout 28 The MODERN THEATRE SECTION