TM 11-6625-928-35
conjunction with testing the microphone ampli-
2. The audio from this switching circuit is ampli-
fier and transmit audio and control signals of
fied by its associated headset amplifier and ap-
comm cent No. 2 under test.
p l i e d back through the maintenance kit and
f. With COMM CONT TEST switch S3 set to 3,
HEADSETS 2 connectors J16-B and D to the
a n audio generator output signal is applied
h e a d s e t . A multimeter connected to COMM
through COMM CONT TEST INPUT connector
CONT TEST OUTPUT connector J20 can moni-
J 1 9 , switch S3A, cable CX-10893/AR, and
tor comm cent No. 2 headset amplifier audio with
COMM CONT NO. 2 connector J3 to COMM
COMM CONT TEST switch S3 set to 3, 4, 5, 6,
CONT NO. 2 connectors J1-EE, KK, SS, FP,
7, 8, 9 or 10.
MM and UU of comm cent No. 2 under test (fig.
d. COMM CONT TEST switch S3 permits ad-
ditional tests of the comm cent No. 2 under test.
switch set to 1, 2, 3, 4 or 5, or comm cent No. 2
The following paragraphs discuss the circuit dif-
receiver toggle switch 1, 2, 3, 4, or 5 set to ON,
ferences as switch S3 is rotated from one posi-
am input is applied to the headset amplifier. To
tion to the next.
obtain an input at comm cent No. 2 connector
e. With COMM CONT TEST switch S3 set to
J1-UU, the AUX switch on comm cent No. 2
1 or 2, the output of the audio generator con-
under test must be set to ON. The output from
nected to COMM CONT TEST INPUT connector
t h e audio generator is applied through the
J19 is applied to the microphone amplifier in the
switching circuit in comm cent No. 2 under test
unit under test (fig. 53 ). The microphone am-
to the headset amplifier. The output of the head-
plifier under test is enabled when HEADSETS 2
set amplifier can be monitored on a multimeter
switch S7 is held at INTERCOM. The output of
c o n n e c t e d to COMM CONT TEST OUTPUT
the microphone amplifier can be monitored on a
connector J20 with COMM CONT TEST switch
multimeter connected to COMM CONT TEST
S3 set to 3, 4, 5, 6, 7, 8, 9 or 10. This output can
OUTPUT connector J20 only when switch S3 is
also be monitored on a headset connected to
set to 1. With COMM CONT TEST switch S3
HEADSETS 2 connector J16.
set to 2, HEADSETS 2 switch S7 held at TRANS-
g. With COMM CONT TEST switch S3 set to
MIT and the selector switch on comm cent No.
4, an audio generator output signal is applied
2 under test changed from ICS to 1, 2, 3, 4 or 5,
through COMM CONT TEST INPUT connec-
the output from the microphone amplifier of the
tor J19, switch S3A, COMM CONT NO. 2 con-
u n i t under test is applied to COMM CONT
nector J3h, cable CX10893/AR, the comm
T E S T OUTPUT connector J20. With switch
cent No. 2 connector J1HH directly into the
S7 held at TRANSMIT, a ground from E15 is
headset amplifier (fig. 5-4). This input is ap-
applied through TB3-6, 5, 4, 3 and 2 to the
plied independently of any switch position on
comm cent No. 2 under test through COMM
the unit under test, The headset amplifier output
CONT NO. 2 connector J3-M, cable CX-10893/
circuit is the same as previously discussed in f
AR, COMM CONT NO. 2 connector J1M, con-
above.
nector J1K, connector J3-K, closed contacts 2
h. Additional audio input circuits of comm cent
and 3 of switch S7, connector J3B, and connec-
No. 2 under test can be checked as the audio in-
tor J1B to the microphone transmit control line.
put is changed from comm cent No. 2 connector
This ground activates a relay in the switching cir-
J1-HH to comm cent No. 2 connectors J1WW,
cuit and enables the microphone amplifier. The
VV, DD, RR, LL and FF by rotating COMM
amplifier transmit audio output is applied to
CONT TEST switch S3 to 5, 6, 7, 8, 9 and 10, re-
COMM CONT NO, 2 connector J1F, L, P, R or
spectively (fig. 54 ). When the audio is applied
V, depending on the position of the selector
to comm cent No. 2 connector J1-WW or W,
switch of comm cent No. 2 under test. The
the NAV switch of comm cent No. 2 under test
ground applied to connector J1B is reapplied,
must be set to ON if the output of the headsets
through an isolation diode in the unit under test,
amplifier is to be monitored.
to connector J1-J, N, T, X or BB as the transmit
signal output to CONTROL SIGNAL light DS2,
2-5. Automatic Direction Finder Circuit
depending on the position of the comm cent No.
Analysis
2 selector switch. A ground appearing at one of
these five pins causes CONTROL SIGNAL light
a. The automatic direction finder tests that are
DS2 on the maintenance kit to light with COMM
performed using the maintenance kit require that
CONT TEST switdh S3 set to 2. COMM CONT
the maintenance kit be inserted between connec-
TEST switch S3 positions 1 and 2 are used in
tor 1J2 on the adf receiver and connector 2J1 on
2-6
Change 3
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