0 0 0 0 0
0 0 0 0 0 0 0
5101 ISU
Fig. 5 9 - Location of 440A (MD) or 4788 KTU,
TOUCH-TONE Adapter
A 8
c
0
E
F
G
H
0
0
0
0
0
0
0
0
24
1
RS I
0
*
CG
0
024
P/0 C O N N B L K I
* FA C T O RY PROV I D E D ST RA P
Fig. 60-Removal of RS1 to CG Strap for TOUCH-TONE
Intercom
5. GENERAL MAINTENANCE
5.01
Maintenance of the 7 A Communication System
is limited to normal station repairs and
wiring checks of the KSU and replacement of
defective components.
5.02
For more detailed maintenance information,
refer to Part 6 of this practice.
5.03
When trouble is encountered,
first make
a thorough check of all connections,
then make the following checks before replacement
of KTUs, power unit, or KSU is considered.
ISS 3, SECTION 5 1 8-450-1 00
5.04
Check as follows:
570A KSU
•
Fuses in place and not blown.
•
Lamps not burnt out.
•
KTUs securely mounted in proper connectors
with retainers and/or guide asemblies in
place.
•
Check wiring on connecting blocks.
EXTERNALLY MOUNTED UNITS
A. 33A Voice Coupler
•
Fuses not blown and positioned properly.
•
COAM music source operative and meets
requirements in 4.37.
B. 20A-49 Apparatus Unit
•
Volume control (potentiometer) not turned
off on unit.
•
Volume control (potentiometer) not turned
off on K8 loudspeakers.
C. 22A-49 Apparatus Unit
•
Unit fastened securely and mounted in a
vertical position.
D. Loudspeakers
•
Check wiring and connections.
No field maintenance is to be performed on the
externally mounted units.
KTUs
•
Securely placed
m
proper connectors.
•
Replace a suspected KTU with one known
to be in good working order to determine
whether trouble is in KTU or external to
it.
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