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. An Improved Wrench for Allen and Bristo Set Screws Tightening the Allen set screws on motor couplings, and Bristo screws on Erpi motor couplings requires the use of an Allen or a Bristo wrench and usually a pair of pliers. There is little room to work in and it is an awkward job. Recently I purchased a 6-inch fairly heavy screw driver with a plastic handle. I sawed off the blade, chucked the handle in a lathe and drilled a hole in the shank of proper size to take the Allen or Bristo wrench. Then I cut off the short end of the wrench, and after insertion in the shank of the screw driver I brazed it in place. If the work is done carefully, the temper of the Allen wrench is not lost. Total cost was 45c for the screw driver and 50c for the use of the lathe and torch. Now I am sure all of my motor coupling set screws will be kept tight. — Ted DeVore. RCA. Removing Excess End Play in Soundhead Motors An excellent and permanent method of removing excessive end play in soundhead motors is to remove the dust plug from the end bell and cut a thin slab of cork the desired thickness, oil it and place it between the dust plug in the armature shaft. Since it will constantly be oiled from the bearing, it will outwear several metal shims. — H. W. Prosser, RCA. Correct Method of Using Stranded Wire Most if not all stranded wire is twisted counter-clockwise when made. Practically all right-handed people twist the wire clockwise to tighten the strands before soldering or connecting. If the wire is twisted counter-clockwise, not the normal way, connections hold up better since breakage tendency is lessened, particularly in cases where removal of connection is frequent. — R. H. Bisbee, RCA. Emergency Replacement Spring Recently I had occasion to change a broken half-moon spring in the MI-9050 soundhead. These springs are also used in the lower and upper idlers of the MI-9050 and MI-9001 soundheads. I did not have a new spring on hand, so I made a very good substitute by removing the point and clip from a safety pin and bending both ends. This worked satisfactorily until a new spring was obtained. — Joseph Miller, RCA. Lubrication Hint Solder a wire in the end of the oilcan spout. This will guide the drop of oil to the exact point desired and the wire can be bent to guide it into the hard-toget-to spots. — R. H. Hecht, RCA. Eye Protection for Projectionists A small piece of colored gelatin placed over the tiny mirror that reflects the image of the carbon arc to the paper screen on the top of the lamphouse will ERRATUM To the Editor of I. P.: As my old friends in Altec may be embarrassed by an erroneous statement which appeared in one of their contributions to the "At Your Service" page of the July 1944 issue of I. P., I am pointing it out simply because of the rarity of errors in our standby — I. P. Most of my old cronies and working buddies believe what they read in your worthy magazine down to the last dot, so I think a note on the correction would be in order, eh? On page 29 of the July issue, under the heading "Strobo Disc for Checking Speed on Machines," there appears a calculation for a negative six revolutions per minute of 354 — 6 the disc as follows: x 90 r= 88.5 360 feet per minute. The expression should 360 — 6 have been x 90 = 88.5 feet per 360 minute. Your publication is improving steadily on its excellent old-time standard, and I still receive immense benefit from reading it. Keep up the great work. Jos. F. Holt, (Member L. U. 692) Signal Sec. Sub. Depot. Co. APO 869, c/o PM, Miami, Fla. [A salute to Brother Holt for discovering this error. As a matter of fact the Altec item as submitted to this office contained the correct, expression, noted above, but the error was due to faulty proof-reading. — Ed.]. have little effect on the brilliance of the image, but will soften it to a point where it will not be irritating to the eyes. It is suggested that a light green be used for greatest eye protection — C. R. Shep ARD, RCA. Correction of Intermittent Increase in Volume All field engineers are familiar with the complaint of intermittent dropping of volume, but when one gets a complaint that the volume is soaring to uncontrolled heights, when you still get too much volume on zero, then that's a horse of another color. In one instance the trouble was finally located as an intermittent capacitor in the feed back circuit. When the capacitor, which was used as a coupling capacitor in this circuit was working properly, it held the overall output down to normal and the volume could be controlled nicely with the volume control amplifier controls. But when the capacitor opened up, the overall volume of the system increased 20% to a point where the volume controls couldn't handle it. A new capacitor corrected this condition and things are now back to normal. — C. R. Shepard, RCA. Improving Scanner Action on the 209 W. E. Soundhead Uneven scanner in the No. 209 W. E. soundhead was traced directly to the drive belt on which, after being in service for about three weeks, a high spot would show itself. This belt was replaced with a 13 x 16 Gates Truex belt which has been in service for the past four months with excellent results. — G. E. Reiger, RCA. Emergency Exciter Lamp Supply Upon answering an emergency call recently, I found the primary burned out of the exciter lamp transformer on the soundhead. Being in a remote area, I was unable to obtain a new transformer immediately to replace the damaged one. By connecting the exciter lamp across the voltage taps in the primary of the transformer on the arc rectifier, I was able to obtain the necessary 8.5 volt a.c. — L. W. Jones, RCA. SEPTEMBER 1944 23