Section IV
T.O. 33A1-3-358-11/TM 11-6625-842-15
Paragraphs 4-24 to 4-28
NAVAIR 16-30APM239-2
4-24. FAULT ISOLATION METER CHECK. The fault isolation meter should be checked for accuracy once
a month in accordance with the following procedure. Accurate standard voltage sources of +20-volts d-c
and 6.3-volts a-c, 400HZ are required to check this meter. If the check indicates that the meter is inaccurate, the meter should
be replaced.
Place the fault isolation meter selector switch to the +20 VDC position.
a.
b.
Apply the +20-volts d-c standard across pins A (+) and M (-) of connector J1 of the meter.
c.
Observe that the meter reads 20 A 1.0-volts.
d.
Disconnect the +20-volts d-c standard and place. the selector switch to the 6.3 VAC position.
Apply the 6.3-volts a-c, 400Hz standard across pins D and M of connector J1.
e.
f.
Observe that the meter reads 6.3 0.3-volts.
Disconnect the 6.3-volts a-c standard.
g.
4-24A. FAULT ISOLATION METER CHECK (AIR FORCE). Forward meter to PMEL at 6 month intervals.
4-25. VOLTMETER AND AMMETER CHECK: The meters must be removed and forwarded to the PMEL at one (1) year
intervals. Calibration of these meters will be in accordance with T.O. 33K1-4-1-17, Section 1611.
CAUTION
INSURE THE LINE VOLTAGE is removed from the test set prior to
removing or installing these meters.
WARNING
Use care when working on the 115-volt a-c line connections. Serious
injury or loss of life may result from contact with this voltage.
a.
Connect the ac-dc differential voltmeter between one terminal of the 2 AMP AC fuse F1 fuseholder
and ground (chassis). Place the METER SELECT switch in the AC position.
b.
Turn on power and adjust the AC CONTROL autotransformer until the ac-dc differential volt-
meter reads 115 volts.
c.
Observe that the test set voltmeter reads 115 volts 4.5 volts.
d.
Turn off power and disconnect the ac-dc differential voltmeter.
e.
Remove 10 AMP DC fuse F2.
f.
Connect the Weston ammeter across the terminals of the F2 fuseholder (XF2) using alligator clips.
terminal connects to the center terminal of XF2 and the - meter terminal connects to the side ter-
The + meter
minal of XF2.
Connect a suitable transponder set receiver-transmitter to TRANSPONDER connector J2 using
g.
the appropriate cable.
h.
Turn on power and energize the receiver-transmitter.
i.
Place the METER SELECT switch in the DC position.
Observe that the test set ammeter reads within 4% of the Weston ammeter reading.
j.
k.
Turn off power, disconnect the Weston ammeter, and replace 10 AMP DC fuse F2. Disconnect
the receiver-transmitter from J2.
4-26. TROUBLESHOOTING.
4-27. GENERAL. Paragraphs 4-28 and 4-29 cover trouble shooting of the test set components. Trouble shoot-
ing should be performed systematically to minimize down-time.
4-28. VISUAL INSPECTION. If the test set fails to operate properly, a visual check should first be performed.
Check for improper control settings, poor cable connections, burned out or charred components or insulation,
and obvious mechanical defects. If the cause of the trouble is not evident, proceed to the localization proce-
dures.
C h a n g e 5 4-5
