International projectionist (Jan 1943-Dec 1944)

ifcfii««^«:.,,. This department is a collection of random thoughts and some not so random; fact, fancy and opinion relating to the man behind the man behind the gun — the serviceman. The prime purpose of this section is to promote a closer relationship between serviceman and projectionist based on a better understanding of their mutual problems through an exchange of news and views, kinks and kicks. To this end, contributions relative to any phase of the serviceman's activities are invited. MANY PROJECTIONISTS are troubled at present because of their inability to obtain the asbestos-covered wire lead used on projection arc lamps. Owing to WPB Limitation Order governing the sale of wire of nearly all types, this wire is impossible to obtain without priority. Bare spots usually occur within the lamphouse, and the heat is such that friction tape, rubber tape, or other common insulation fails to hold up. The insulation that is bad within the lamphouse may be stripped from the wire, which will usually be found in good shape, and Pyrex beads of the proper diameter slipped over the bare wire and threaded on to the wire closely to form the desired insulation. When threaded and held closely together, this forms a perfect insulation from heat and metallic contact and allows maximum flexibility. In lamphouses where the heat does not go too high, it may be found that ordinary glass beads of the proper diameter will do the work. — C. R. Shepard, RCA, Pittsburgh. • • • In 2,000-ft. magazines, it is not easy to raise the reel-end alarm film trolley. Fasten a bracket to the top magazine door near the hinge so it extends above the top edge of the magazine, then a string is attached to it and to the drop-hammer arm on the opposite edge of the magazine and so adjusted in length that when the door is opened the drop will raise the full travel. In this manner, no fumbling past the edge of the full reel is necessary to raise the guide arm when the reel is placed on the top spindle. If the parts are properly located, the string does not catch between the door and the inside edge of the magazine so there is no fire danger. Only 10 inches of string is neejfed for each magazine. — L. W. Leidy, RCA, Cleveland, and C. H. Atchisson, RCA, Kansas City. • • • I recently had occasion to improvise a stage microphone riser drive motor for remote operation, where the only motor available was a one-quarter horse, split phase, with centrifugal type starting switch. The starting and main winding leads were brought out to a double-pole, double-throw switch to provide for reversal and the operation was quite satis factory, except that the repeated "inching" of the motor in this particular service proved rather disastrous to the centrifugal switch contacts. This difficulty was overcome by connecting a 75 watt 110 volt lamp across the starting switch contacts. The cold resistance of the Mazda lamp is low enough to assure ample starting torque while the hot resistance is high enough to prevent damage to the starting winding. While I have not had occasion to use this little stunt in an emergency, it appears that it would be a very satisfactory emergency expedient for operation of projector drive motors or motor generators suffering from starting switch ailments. — E. G. Himenway, ALTEC, Roanoke, Va. On a recent service call inspection of the visual oil level gauges on the MI1050 soundheads showed the oil level to be even with the line engraved on each gauge glass. However, when one of the soundheads was started, the oil level did not drop as it should normally. Investigation disclosed that the oil gauge nipple had been bent downward, resulting in a false level in the gauge. When the nipple was straightened the true oil level was found to be about 3/16" below the mark, and not high enough to reach the holdback shaft gear. Soundhead gear box oil level should be checked by observing the change in oil level when the soundhead is started after having been idle for several minutes. If the proper amount of oil is in the compartment, the level will drop about 3/16" when the above test is made. — J. D. Steely, RCA, Pittsburgh. • • • Remove and check drive gear shafts for dirt, sludge and other foreign material in oil passageway of shaft. This passageway sometimes becomes clogged. Thus, drive pinion and shaft do not have proper lubrication causing undue wear. — E. E. Reiger, RCA, Pittsburgh. • • • A small screw top glass bottle such as a mayonnaise jar makes an excellent oil drainage collector for MI-1040 soundheads. Remove left rear motor mounting bolt, poke hole through bottle cap and place bolt in mounting bracket.. Screw on bottle, fasten small length of tube on to drainage lip of the MI-1040 oil drainage pan, poke hole in bottle cap and insert lower end of tube. Bottle hangs downward from left rear mounting bolt similar to oil collection bottle of MI-9050-30 soundheads.— S. M. Reed,. RCA, Kansas City. • • • Snap switches such as used in W.E. 42, 46, 43, 87 amplifiers, and 706, 708-A and 709 type motor control cabinets,, become stiff and do not operate properly after being in use for several years. By applying oil to all moving contacts, and, shaft, an apparently worn-out switch will resume full operating capabilities, eliminating need for a replacement. — E. D.. Van Duyne, RCA, Philadelphia. • • • In a number of cases, I have found that new tubes and those in service for a short time gave an "open filament" or "burnedout" test on tube checker. These tubes can often be restored to normal operation by heating the filament prongs with a soldering iron, cleaning the filament and leads and inside of filament prongs, then resoldering. Some tubes will actually give a filament continuity test but will not light due to poor contact. — R. T. Bisbee^ RCA, New York. • • • When purchasing chassis lubricant "S" from a Texaco bulk plant, it was found that with no change in name or designation, this grease can be bought in twoforms, one having a consistency of cup grease while the other is stringy. The cup-grease type will not cling to the gears and should be avoided when purchasing this grease. — P. N. Connet, RCA, Kansas City. • • • A case was recently encountered whereuneven take-up action was, corrected by using sandpaper to improve the seating of the fibre disc. This was done by removing the take-up and inserting a circle of sandpaper, cut slightly larger than the friction surfaces, between the fibre disc and the adjoining clutch face. The pulley was then rotated by hand, causing the sandpaper to remove all high spots from the fibre, forming a perfect seat. — J. D. Steely, RCA, Pittsburgh. JANUARY 1943 15