|Audio-visual Communication Handbook (Peace Corps, 1989, 134 p.)|
The difficulties encountered with audiovisual materials and equipment over-seas generally center around the physical environment. Extreme temperatures, moisture, sand and dust, insects, fungus, and bright sunlight all cause specific problems. In addition, electrical power sources vary widely and the equipment you use must match, or be adapted to match the local power sources. Some familiarity with the problems that can be caused by unusual conditions and ways to combat these problems will help you keep your equipment and materials in good condition.
Problems: High temperatures will cause equipment to overheat which in turn may dry up lubricants, cause rubber parts such as belts and drive wheels to deteriorate, and melt wax and plastic insulation. Similarly, dry cell batteries are damaged by heat.
High temperatures will cause films and other sensitized materials to deteriorate very rapidly. Six days at 120° will produce roughly the same aging as six months at 75°. Films will lose speed and contrast, and mottled spots are likely to result. Color reproduction will be noticeably poorer with all color films.
Remedy: Store equipment in as cool a place as possible. When traveling in hot areas, a styrofoam picnic chest is an ideal place to store equipment. For ventilation during storage and operation, allow air space around equipment. Be sure that ing to the instruction booklet or service manual. Be sure equipment, especially lenses, is clean before storing. This will help avoid fungus growth.
Try to purchase film that is fresh and tropically packed. Information on the box will help you know what you are buying. Fresh film will have a date a year or more in the future. Always store film in a cool place. The shelves of a refrigerator are ideal for storing unopened packages, but once opened, packages should not be put back as moisture will be equally damaging. The ideal temperature for storage is about 55°. After removing a package of film from a refrigerator, allow it to warm up before opening to avoid condensation. On a hot sunny day a closed car or glove compartment is probably the worst possible place to store film either in or out of the camera. This common habit should be avoided at all times.
Problem: Below-freezing temperatures can cause rubber and some plastic parts to become brittle and eventually to break. The lubricants in projectors, tape recorders or other equipment with moving parts will thicken in extreme cold and slow down the running speed.
Remedy: Protect equipment from the cold. Where possible, oil moving parts with special low temperature lubricants.
Problem: When equipment is taken from a cold place to a warm humid room, moisture will condense on cold metal. This is damaging to any precision equipment.
Remedy: Protect equipment from the cold. Cameras, film and small equipment can be carried inside your coat where body heat will keep it warm. Try to prevent condensation by avoiding rapid temperature changes. If condensation does occur, carefully wipe off the condensed moisture. If condensation has formed when there is film in the camera and you want to take pictures, wait until the moisture on the outside has evaporated, then wait a bit longer. This is a good indication that moisture on the inside of the lens has cleared. Lens cleaning tissue should be used on optics, but any soft tissue can be used if you are careful to avoid rubbing.
Problem: Moisture and audio-visual equipment are incompatible. Moisture can cause electrical problems, oxidize metal, promote fungus growth, and cause leather to deteriorate.
Remedy: Protection from all moisture is excellent insurance. A plastic bag around equipment is probably the best way to keep things dry. Wrap the equipment in a clean cloth before putting it in a plastic bag. A very light coat of thin oil on exposed surfaces and a coat of wax or leather preservative on leather surfaces can reduce problems.
Despite care, sometimes you may get rain water or even salt water on equipment. As quickly as possible, wipe all the water off exposed surfaces and oil lightly. If you suspect that salt water has seeped into your camera, rinse in fresh water (distilled if possible), then send it to the nearest professional repairman or to the factory for cleaning.
Problem: High humidity can be as damaging as direct water and usually is not noticed as quickly. It will cause the same equipment problems as other moisture.
Remedy: Humidity can be controlled in several ways. A storage closet with a dehumidifier is ideal if available. A good substitute is a closet with a small heater or a lamp near the floor and ventilation holes at the top. Slatted shelves and careful placement of equipment to allow air circulation will help reduce moisture still further. Small equipment can also be stored in a sealed container with a desiccant such as silica gel, calcium chloride, or dried rice. Silica gel is sold in small cloth bags which have a moisture indicator on the outside. Place the desiccant bag and your camera or other small equipment in a largemouth jar with a screw top. When the indicator shows the desiccant is saturated, it can be placed in an oven at a temperature of 400 degrees for a couple of hours to dry it out. Stir silica gel occasionally while drying. It will look pink/white when saturated and blue when dry.
Larger pieces of equipment can be stored in a box with a tight fitting lid and some desiccant. A picnic chest is ideal. Do not store leather cases with your camera as the leather probably holds a potentially damaging amount of moisture, and usually holds fungus spores.
Problem: High humidity is equally damaging to many graphic and photographic materials. Moisture on film will cause problems similar to those produced by heat.
Remedy: Use tropically packed film and store it in a cool, dry place until used. After a package of film has been opened, use it and have it processed as soon as possible. If it must be stored, use a closed container with a desiccant.
Graphic materials such as paper, cardboard, and mounting materials should be kept dry. A closet with slatted shelves and some means of drying and circulating the air will work well. Processed films are very susceptible to moisture damage. Negatives and slides should be protected by storage in a cool, dry place. Slides mounted in aluminum or plastic mounts are less likely to be damaged by moisture than those in cardboard mounts because the cardboard itself absorbs moisture. Glass mounts increase the chance of fungus growth. Filmstrips should be placed in a metal or plastic container with a loose-fitting top (or the top removed) and stored in a dry container. Be careful to avoid all finger marks on slides or filmstrips.
Sand and Dust
Problem: Sand and dust can get into almost any equipment and cause faulty operation of volume controls, tone controls, switches, shutters, and timers. Even small amounts of dust and dirt will cause film scratching in cameras and projectors and will cause excessive wear of tape recorder heads and all moving parts.
Remedy: When not in use, store all equipment in dust-proof cases or plastic bags. Clean equipment frequently! Cleaning should be done with a soft cloth or a soft brush. Lenses should be cleaned with a lens brush and lens tissue. Other soft tissues can be used, but never use silicone-treated tissues which damage the surface of coated lenses used in most modern cameras. If sand does get into a camera shutter or projector mechanism, do not try to operate until it has been thoroughly cleaned.
Problem: Fungus growth, usually associated with warm, humid conditions, can damage lenses, leather goods, paper products, photographic materials, projection screens, and other materials.
Remedy: The general rules for equipment care in tropical climates will help you avoid fungus damage. Keep all equipment and materials dry and reasonably cool. Anti-mildew powders are available, but they may affect photographic materials. Prevention is much better than cure. If fungus does start to grow on lenses, color slides, or other materials, clean them as quickly as possible. A soft cloth and a film-cleaning solution, available from most photo dealers, will remove light fungus if caught in time. Plastic projection screens can be washed with warm soapy water and dried thoroughly. Projecting films and slides occasionally and keeping all equipment clean and dry is the best deterrent to fungus growth.
Problem: Insects can cause a variety of problems to many kinds of equipment. They can jam delicate mechanisms in cameras, projectors and tape recorders. They can eat insulation on electrical equipment causing short circuits, and they can damage projection screens with stains that are difficult to remove.
Remedy: Keeping equipment in closed containers and dusting lightly with insecticide can help prevent insect damage. Ventilation holes in equipment can be covered with fine mesh screen to prevent insects from entering, but be careful not to block off all air circulation. Do not roll up a projection screen immediately after an evening film showing. Insects rolled up in the screen cause stains that are difficult to remove.
Problem: Excessive, intense sunlight can cause damage by bleaching colors in paper, cloth and photographic materials. Dial markings on some equipment and many plastics can be damaged by continued exposure to strong sunlight.
Remedy: Protect equipment and materials from direct sun whenever possible.
There are a few general suggestions regarding equipment that will help you to avoid many problems.
1. Obtain simple, rugged equipment rather than complicated equipment even if it means sacrificing some versatility.
2. Transistorized electronic equipment generates less heat and is lighter in weight than tube-type equipment. However, transistorized electronic equipment is also a bit more difficult to repair.
3. All photographic materials should be kept dry and cool (not frozen) and processed as soon as possible after shooting. In most places, sending film to the lab by air will reduce the chance of damage. If you must leave film in the camera, keep it in a desiccated container in a cool place.
4. All electronic equipment is susceptible to moisture. Keep it dry. Electronic flash units can be purchased that use rechargeable batteries or disposable batteries. The rechargeable units tend to be more delicate, but they are more economical when many flash pictures are to be taken and correct power sources are available for charging. Disposable units are less susceptible to damage, but batteries must be replaced occasionally and are sometimes difficult to find.
Whenever possible, use sealed, dry batteries in your electronic equipment. They have longer life and are less likely to leak. Always remove exhausted batteries from equipment to prevent damage from leakage.
5. Lenses of all kinds should be well protected. Covers are essential when not in use. When in use, a haze or ultraviolet filter over the lens will protect it from moisture and dust.
6. Keep tape recorder heads clean, and remove dust and oxide carefully with a recommended tape recorder cleaning solution or alcohol (spirits). Do not use alcohol on the pressure roller as it will cause the rubber to deteriorate.
7. When buying projection bulbs try to get bulbs that are rated higher than the normal line voltage, i.e., order 230 volt bulbs if the line voltage is normally 220 volts. Order 11 5-volt bulbs if the line voltage is normally 110 volts. This will reduce damage due to up" ward voltage surges.
8. Always read instruction books carefully.
The electrical requirements for most audio-visual equipment can be understood easily even though they are sometimes clouded in seemingly meaningless nomenclature. A few guidelines can help you avoid problems of blown fuses or burned out motors and lamps.
- There are tour characteristics of electrical power supplies that need to be considered.
1. The kind of current expressed as AC (alternating) or DC (direct) current. Most generator plants produce alternating (AC) current. Dry cells, car batteries, and some generators furnish direct (DC) current.
2. The pressure or voltage of the current.
3. The amount of current available or used by a piece of equipment or appliance measured in amperes.
4. The frequency of alternating power sources expressed in cycles per second.
- You must match the electrical requirements of the equipment you are using to the available source. The instruction booklet and the nameplate on most equipment states the amount and kind of voltage required, the current consumption in amperes and the cycles, if applicable.
1. Use the proper kind of power. If you operate motors, heaters, amplifiers or lamps on the wrong kind of current (AC instead of DC, or vice versa), they may not operate and they can be seriously damaged.
2. Match source voltage to equipment requirements. With low voltage most equipment will not operate properly and can be damaged. Excessively high voltages will almost always cause serious damage. Transformers can be used to reduce the 220 voltage found in many places to the 110 volts required for most United States' equipment. It is well to note that the voltage of electricity supplies can vary widely. A shortage of generating equipment in many countries results in overloads and decreased voltage during periods of high use. It is entirely possible that voltage can vary from less than 100 volts to as much as 240 volts in a few hours.
3. Check to be sure there is ample current available to run your equipment. The current available usually depends on the fuses that are in the circuit. A fuse is a safety device that will burn out if the circuit is overloaded with too many lamps, motors, heaters, etc. If there were no fuses, the wiring or even the generator might burn out causing power failure and/or a fire. Most circuits in schools, houses, and offices are fused for about 15 amperes. The amperage used by a piece of equipment is usually on the nameplate. Sometimes wattage is given instead. In that case divide the wattage by the voltage to find the amperes. For example, a 500-watt projector on a 110 volt line will use about 5 amperes. Remember that equipment in several rooms of a building may be operating on one circuit. The total amperes being used is equal to the sum of the amperes of the individual pieces of equipment in use.
4. Using current of the wrong number of cycles will not damage equipment, but motors will run at the wrong speed. A 50-cycle tape recorder will run 20 per cent faster if operated on a 60-cycle line.
- Try to purchase equipment that is designated for the electrical sources available to you. Many items are now available with relatively simple adjustments to adapt to varying voltages and cycles.
- Carry a stock of adapters that will enable you to use your equipment with a variety of wall receptacles. In some places as many as four different receptacles can be found in the same building. It is always a good idea to carry an extension cord as they are needed frequently.
- Carry spare bulbs, fuses, batteries and other items with a short life.
- Always be careful where electricity is concerned. Never use makeshift electrical connections. A mistake can be fatal.