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TM 11-5820-890-20-2
2-129
2.2.
TROUBLESHOOTING FLOWCHARTS. Continued
Chart 36
NO RT-A MODULATION FROM CREWMEMBER C 2298.
(Sheet 4 of 6)
Set up multimeter as an ac voltmeter.
Use the lowest range. Connect meter
probes between signal line or a test
point and chassis ground. Key the
handset and whistle into the mic. Look
at the meter and note any change in the
ac voltage. The change indicates the
presence of the talk signal. The reading
will be less than 1 volt.
V
U
T
S
R
P
N
M
L
K
J
H
F
E
D
C
B
A
AM 1780 J501, J505, J506, J507
C 2297 J901
F
K
J
A
D
H
E
C
B
NO
YES
AC VOLT
CHANGE
?
1. CONNECT CX 7060 TO AM 1780 J505 J507
AND CX 13300 TO AM 1780 J501.
2. OBSERVE CHANGE IN AC VOLTAGE AT
C 2297 J901, PIN K TO PIN A (GND) (SEE
NOTE).
3. PRESS PTT AND WHISTLE SHARPLY INTO
HS.
REPLACE C 2297.
1. REMOVE CX 13300 AT AM 1780 J501.
2. REMOVE SUSPECT CX 4723/7060 FROM
AM 1780 J505 J507.
3. CHECK CONTINUITY AT AM 1780
J505 J507, PIN K TO J501, PIN U.
NO
YES
C 2297
SUSPECT
?
6
SH 5
7
SH 6
NO
YES
OPEN
?
REPLACE AM 1780.
4
SH 4
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