TM 11-6625-648-12
Item No.
Checks and corrective measures
Probable trouble
Trouble symptom
Higher category
a. No audio in H-91A/U
3_ _ _ _ _ _ _ _
maintenance is
is inoperative.
when talking into
required.
microphone, but
1,600-cps tone is heard
with ORDERWIRE
switch operated to SIG.
H-91A/U is inoperative.
Substitute for operable
b. No audio in H-91A/U
H-91A/U.
w h e n talking into
Higher category
Receiver amplifier is
microphone with
maintenance is required.
inoperative.
ORDERWIRE switch
at TALK.
Higher category
Antiring circuit is faulty.
c. CALL lamp flickers while
maintenance is required.
talking.
Interchange test cable
Poor cable connection
a. TEST METER fails to
1
c o n n e c t o r s and repeat
or faulty internal
deflect for either
step. If not corrected,
circuit.
CAP test or RES test
h i g h e r category
while DISTANCE TO
maintenance is
FAULT switch is
required.
operated.
Higher category
b. TEST METER fails to
maintenance is
portion of bridge
deflect during CAP
required.
circuit is faulty.
test, but does deflect
during RES test.
Higher category
c. T E S T METER fails to
maintenance is
part of bridge circuit
deflect during RES
required.
is faulty.
test, but does deflect
during CAP test.
Higher category
Faulty bridge circuit_ _ _ _ _ _ _ _ _
d. DISTANCE TO FAULT
maintenance is
control does not
required.
indicate cable length
within 250 feet.
Substitute for a pair of
One or both orderwire
a. CALL indicator lamp
2_____
operable order-wire probes
probes are defective.
fails to become
and repeat the step.
illuminated, buzzer
fails to sound, and
and audio cannot be
h e a r d on headphone.
Replace indicator lamp.
CALL indicator lamp is
b. CALL indicator lamp
faulty.
fails to become
illuminated, but
buzzer sounds.
Higher category
Buzzer is faulty_ _ _ _ _ _ _ _ _ _ _
c. Buzzer fails to sound,
maintenance is
but CALL lamp
required.
becomes illuminated.
Substitute an operable
Pcm probe or PROBE
TEST METER fails to
3-------
probe. Check PROBE
connector is faulty.
indicate properly.
connector. If fault is not
corrected, higher category
maintenance is required.
4-6. Repairs and Adjustments
or the lamp in the call indicator. The pro-
Operator and organization repairs and ad-
cedure to be followed for replacing the BA-
justments for the AN/PTM-7 are limited to
replacement of the H-91A/U, probes, batteries,
4-5