TM 55-4920-390-13&P
6-5. FUNCTIONAL TESTS . If
resistance Checks are OK, proceed as
follows. Refer to
Voltage Check Chart, Table 6-3,
as required.
a) Plug Strobex into 28 VDC source. Observe polarity. Pilot light will not light if polarity is reversed.
b) If light does not light, check fuses and pilot light bulb, cables, connector,etc.
c) Set "Vernier" on rear of hand-held lamp full CCW (internal oscillator off). Depress trigger in pistol grip handle
and listen for a 3 KHz. hum (singing). Check that current drawn by the Strobex (with no pulsing) is between .3
and .6 amps. A greater current drain indicates a faulty power supply section.
NOTE
If 28 VDC source does not include an ammeter, use the ammeter section of the voltohmmeter in
series with 28 VDC line to make above current measurements.
NOTE
If 3 KHz tone is heard and current drain is OK, proceed to Step f.
NOTE
Test Point 1 should read about 27 VDC when trigger is not depressed, and about .2 VDC when
pulled.
d) Apply 28 VDC and try again. If hum is still absent, remove power, and "lift" one end of each of the four diodes,
D5, D6, D7 and D8. Check the diodes for forward and reverse resistance.
e) While diodes are disconnected as in d, pull trigger. Three KHz. Should be heard and current should be .3 to .6
amps. Restore diodes, replacing as required.
This should check out the power supply section.
Proceed to Step f.
f) Connect 28 VDC supply and apply a 1 volt RMS (2.8 V peak to peak) sine wave at 20 Hz. to the signal input
cable ("+" to pin A and "-" or ground to pin B). Turn "Vernier" on rear of hand-held lamp full CCW to turn internal
"oscillator" off. Turn "Gain" full CW, depress trigger on hand-held lamp. Lamp should flash at 20 flashes per
second.
6-5