International projectionist (Jan 1943-Dec 1944)

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. Head-Sets Connected to Sound Systems We have had several calls recently due to defective head-sets or cords. If you have any head-sets in your theatres which are used regularly by the projectionists, connect a 500-ohm resistor in each side of the head-set leads. This will act as a limiting resistor and unquestionably will save some calls. — D. L. Turner, ALTEC. Handling Preview Dater Strips While many ways have been devised for the handling of preview dater strips, here is one of the neatest and best I have seen. Take ordinary gummed paper tape like that used for sealing cartons, about \x/± inches wide, and by rolling it up with several thicknesses into a paper tube about an inch in diameter, you will have a convenient tube for each dater. They are then labeled on the outside and placed in neat rows in a cigar box or other suitable container where they are free from dust and damage. — C. R. Shepard, RCA. Drive-In Theatre Equipment Kept Dry Each fall, when we shut down for the year, we close the amplifier racks into a small room with half a dozen layers of heavy wrapping paper. We then take about three sets of electric heater units and connect three units in series, making a total of nine units so connected that they just show red in the dark, so there is no danger of their burning out. These units are placed inside the little boxed-in space to keep them dry and warm. It is possible to run a show, as far as sound is concerned, within fifteen minutes of opening up the equipment when re-opening the theatre after the winter shut-down. — R. H. Hecht, RCA. Adjusting Changeover Knob on RCA PG-139 System The PG-139 voltage amplifier changeover switching knob that is mounted in the door of the voltage amplifier is engaged to the switch by two pins that engage adjacent slots. I recently ran across a case where these pins were not extending far enough so as to engage. Also, occasionally the sound changeover would be missed and the projectionist would have to run to the other cabinet to make the changeover. I found that there were two nuts on the back of this mounting and by installing one of the nuts on the front of the assembly, or by using a washer, the pins could be made to engage further into the slots. — H. M. Morrow, RCA. Breakage of Pyrex Deflectors in E-7 Rear Shutters Breakage of deflectors is an expensive and dangerous condition, some projection rooms encountering more of it than others. The projectionist in a theatre that had considerable of this trouble discovered a simple and very effective means for overcoming this condition. He purchased sheet asbestos, the type that is used on hot air furnace pipes, and cut two circles the diameter of the deflector glass, and then cut out the center leaving a ring about one-half inch deep. A ring of the asbestos was placed on either side of the deflector which was then mounted in the holder, thus no metal touches the glass and breakage is avoided. — H. M. Morrow, RCA. Fixing Stripped Threads in Stud Hole For Pad Roller on 206 Jobs A very satisfactory repair was effected in the case of a 206-type reproducer set that had stripped threads in the pad roller stud holes. One of the vented pipe plugs used in 709 drives was drilled out and tapped to fit the stud and the head cut off even with the last thread. A slot was cut across the plug to fit a large screwdriver. The reproducer set CUT OFF i I I 1 DRILL 6 TM* FOR STUD casting was drilled and tapped for a %" pipe plug, the tapping progressing carefully until the modified plug was flush with the surface when screwed in tightly. —P. J. Aubry, ALTEC. Repairing Tungar Bulb Sockets In an effort to get perfect contact, some projectionists screw in the tungar bulbs so tight that they literally uproot the screw shell of the socket, pulling it loose from under its mountings and sometimes shorting out the filament secondary so that it becomes impossible to use the emergency a.c. winding. These • sockets can be repaired in the field by obtaining a cleat base porcelain receptacle, and by boring out the rivets the screw shell can be removed from it. With slight modifications to allow the center to straddle the horseshoe mounting cleat, this shell will fit perfectly and make a nice clean job. At the time it is installed, I also solder a jumper from the wire terminal direct to the side of the shell, which will by-pass any possible loose connections caused by the retaining screws. — C. R. Shepard, RCA. Eliminating Soundhead Drive Motors Pound Recently we had trouble with a drive motor pounding. We found the rear bearing rough and replaced it. The motor still continued to pound. On rechecking, we found that the first ball bearing had locked causing the inner race to slip on the shaft and wear it down a little so that the new bearing was loose on the shaft. If the inner ball race is not tight on the rotor shaft, the motor will pound. Since I have experienced the above trouble, I have checked the drive motors on several other soundheads and found that the same condition in the front bearing will make these motors run noisy. The proper way to have this condition corrected is to have a motor repair shop build up the shaft and turn it down to the correct size. — R. 0. Northrup, RCA. Emergency Gear Repairs Here are two practical methods for effecting temporary repairs to broken gears where a replacement is not immediately available. The first, applicable to metallic gears, is to fill in the damaged section with brazing metal, and with a hack saw and (Continued on page 27) OCTOBER 1944 21