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1950-51 Theatre Catalog, 9th Edition, Page 445 (421)

1950-51 Theatre Catalog, 9th Edition
1950-51 Theatre Catalog
1950-51 Theatre Catalog, 9th Edition, Page 445
Page 445

1950-51 Theatre Catalog, 9th Edition, Page 445

to remove the carbide deposit which remains.

Rust spots which remain on unpainted surfaces should be polished off with steel wool or crocus cloth and re-oiled. Where rust has started on finished surfaces, due to chipped paint, it should be thoroughly removed before a touch-up job is done. Painting over corroded surfaces does not stop the rust, for it continues to form and eventually causes the paint to peel.

All oil-bath gear boxes, intermittents, etc., should be drained, flushed, and refilled in accordance with the recommendations of the manufacturer. Similarly all grease-packed gear boxes should likewise be drained, flushed, and repacked with the proper grade of grease. Sound head scanners and/or flywheels should be thoroughly cleaned and relubricated. The projectionist should then go over' and readjust the projector completely, as well as clean and check the projection lenses and the lamp houses. Motors, generators, exhaust fans, and other rotating equipment should also be cleaned and serviced under the supervision of competent motor maintenance


Sound Equipment

The sound equipment, due to its delicate nature, requires more than ordinary attention.

Starting at the film path, the optical system is checked for damage to lens and slit assemblies, mirror silver-ing, exciter lamps and lamp bracket assemblies, along with the condition of the photo-cell. Under extreme adverse wine ter conditions the optical components are often removed for storage in a more favorable location, but, in either case, a check on the accuracy of adjustments or readjustment must be made with specialized equipment described in detail below.

Continuing in the sound head, the scanner, sprockets, rollers, tension pads, etc., are inspected and adjustments reviewed and worn or defective parts are replaced. Sound head wiring must be examined for possible damage to insulation by oil*a very potent trouble source. Necessary repairs or replacement should be effected at 'that time.

Proceeding from the sound head to the pre-amplifier, volume controls and changeover devices are then checked. ,Tubes are removed for testing and contact cleaning. Amplifier chassis are best cleaned by air blast, heated if possible. closely adjacent contacts, such as those at tube sockets, must be examined for possible short-circuit paths. Volume controls are cleaned, and a special lubricant applied. Changeover switch contacts are burnished and checked for ilfollowll in Operation.

Advancing to the Voltage and power amplifiers, tubes are also tested and visual examination made for poor connections and unwanted leakage paths. In the case of the power amplifiers, operating voltages approaching 2,000 volts are often present at various points in the circuit. Transformers and condensers in these high-voltage circuits are necessarily large and expensive. It is extremely important that the amplifiers are not turned on until the service


YOUR .SERVXCE CONTRACT will take care oi all projection and sound equipment. Above. Altec Inspector making adjustments in amplifier. and examining sound head while projectionist adjusts lamp. Below. the projectionist cleans and services the motor generator, and inspector McLean checks the junction boxes and the speakers for flaws or loose connections.

inspector, using his test equipment and technical knowledge, has determined that no leakage path that might damage components exists.

Exciter power supplies are examined in a manner similar to that used for the amplifiers. After the system is turned on, any emergency section of the supplies is adjusted so as to provide exciter filament voltages equal to that of the regular supply. .

The next checking point will normally be the ramp control panel, wherein switches must be burnished and adjusted for proper pressure. Normally, it is desirable to replace all fuses in the power circuits, since deterioration, resulting in lowered carrying capacity, can occur under damp conditions. The various line voltages, under load, should be checked and adjusted to assure that power service is normal. Should line voltage conditions be abnormal the local power company should be consulted.

While the foregoing is in progress, it is usually economical to have the previously tested in-car speakers reconnected.

The system is then turned on and allowed to warm up thoroughly while preparation is made for the transmission test. Included in the requirements for this test will be a calibrated multifrequency film, lens loop, buzz-track, flutter film, a volume-indicating meter, and a decabridge. If results of the test indicate a need for readjustments or other investigation, an audio-oscillator, nutter bridge, ohmmeter, and/or voltmeter might be required.

The transmission test is an all-embrasive method, positive but requiring a minimum of time, which provides a check on the optical system settings and performance of the tubes and amplifiers to assure that amplifier and speaker connections are arranged for the best possible volume and quality at each speaker. The inspector has only to refer to the previous transmission test report or the manufacturers recommendations to evaluate quickly the overall condition and determine what corrections are required to overcome system component deterioration or changes in the recording art.

Once the system response is satisfactory, a regular sound reel or the SMPTE ASTR-4 reel should be run to allow checking on operation of all ine car speakers and to permit the projectionists to re-familiarize themselves with the system controls and settings.


It is essential that the importance of the foregoing recommendations to satisfactory operation of the equipment be recognized by the drive-in exhibitor when he is reopening his theatre. The time required will be repaid many times in reduced operating troubles and savings in costly repairs and equipment replacement.

During the operating season, routine servicing, coupled with emergency service as required, has proven its Worth through hundreds of thousands of hours of operation, in hundreds of drive-in theatres. Under present economic conditions, made more acute by impending material shortages, it is sheer folly on the part of the outdoor theatre operator to be guilty of negligence in this 'regard.
1950-51 Theatre Catalog, 9th Edition, Page 445