TM 55-4920-390-13&P
WARNING
When the Signal Cable is plugged into the magnetic pickup, it passes in the area of vital moving
parts and IT MUST BE SECURED so as to guarantee that it cannot foul the mechanism. It should
be secured with tie-wraps or equal, and must have sufficient slack to permit full articulation and
motion of the swash plate.
e) Turn up the helicopter. As soon as the 28 VDC receptacle, into which the Strobex has been plugged is hot, the
Strobex "Pilot" light will light. Operation of the Strobex and its oscillator can now be verified by depressing the
pistol grip trigger (the vernier must be turned at least part way CW). The light should flash at a constant rate as
determined by setting of Multiturn Dial.
As soon as the rotor is turning, the adequacy of the locking pulse from the magnetic pickup can be verified. Turn
vernier control full CCW, thus disabling the oscillator, depress the trigger, and the light should flash once per rev
(very slowly). (If not, turn Gain Pot full CCW. Then advance knob CW until steady flashing results. Advance
knob only 10-20farther to assure "solid" input while not introducing "noise" and extraneous signals. If flash is
still not proper, check the gap between pickup and wiper (ten to twenty thousandths), continuity of wiring, etc.)
f) With operation of the light thus verified, direct the hand-held light from within the helicopter toward the blade tip
path. With the vernier control full CCW (oscillator disabled) depress the trigger to cause the light to flash once-
per-rev. Sweep the light slowly in azimuth until a retro-reflective tip target is seen. Now turn the vernier control
CW. This activates the oscillator and the flashing rate of the light will increase to "n" times the one-per-rev rate
(assuming "n" blades). Adjust the vernier control (thus oscillator rate) so that all targets are superimposed or
"stacked". Now the vernier can be adjusted slightly to spread the pattern left or right to suit the preference of the
operator.
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