5 mm. speed,, The shot arrival time evaluator (see paragraphs 108 through 

 114 below) should be used to check the time index interval for both speeds, 



operati 



Inserting Paper Tape 



52» Just to the left of the clutch control system is the index relay and 

 writing stylus carriage assembly (Fig„ 23) „ Normally, the carriage is 

 latched into place, the latch control lever being just to the right of 

 the relay coil„ When it becomes necessary to insert a new roll of paper, 

 the carriage assembly must be unlatched by gently pulling the latch control 

 lever to the left and at the same time raising the assembly which is pivoted 

 at the left-hand side To prevent the writing pen from dropping from its 

 guide, with possible injury to its sapphire writing tip, it must be set at 

 20 on the writing scale before the carriage is lifted o Place a new roll 

 of paper on the spindle behind the carriage, being sure that the holes 

 along the paper edge are properly lined up over the drive sprockets located 

 in front of the carriage assembly, When the paper is in place j, gently 

 lower the carriage assembly and make certain that it latches properly <> It 

 will be noted that along the lower side of this carriage assembly is a row 

 of short, pointed pins which are spring loaded (Fig, 24) ,. These pins engrave 

 equally spaced db division lines along the length of the paper, so that the 

 level of the signal with respect to background, etc., can be determined,, 



53° Mounted on the upright metal strip which shields the tubes from the 

 paper-drive system just described is another relay. This relay operates 

 on 115 volts AC and controls the indexing relay on the carriage assembly. 

 Its coil is connected across the recorder motor and it is thus activated 

 by the MOTOR switch,, It was installed to prevent the indexing relay from 

 operating when paper is not being fed through the machine^ causing the 

 indexing stylus to dig into the stationary paper and stopping the paper 

 from feeding freely at the arrival of a shot Make certain that the cables 

 to this relay do not impair the paper tape feed D 



the Signal J]npjitJ?otejgtiome ter 



54o To the left of the carriage assembly is a box With two small knurled 

 knobs and two binding posts at one end,, This is the signal input potentio- 

 meter, across which the signal from the bus is applied,, The potentiometer 

 can be removed by unscrewing the two knurled fastening knobs and lifting 

 up Pins are located on the bottom of the potentiometer to facilitate re- 

 placement, When changing the potentiometer do not sere?; the knurled knobs 

 too tightly or the sliding arm will binds 



14 - 



