AT&T Bell System Plant Series Installation And Maintenance Manual page 5

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(a)
Cleaning
• Clean plastic covers, housings, and hand-
set with water dampened KS-2423 cloth or
equivalent.
• Do not use scouring powders or cleansers
on colored apparatus .
• Do not allow excess water to enter grills
of loudspeaker units.
• If cleaning does not produce the desired
effect, replace the component.
(b)
Inspecting
• Housings or covers should not be warped
or discolored.
• Turnbuttons and volume controls should
work freely without binding or sticking.
• Wiring and mounting cords should be
checked for damage to the insulating
covering and should not be placed to pre-
sent a hazard to customer or equipment.
• Screen behind louvers of control unit cover
should
be
intact and free of obstructions.
(c)
Troubleshooting
• Table B provides
a
list of the more com-
mon troubles encountered with 2A farm
interphone and their probable causes with
recommended corrective action.
(d)
Connection Index
Fig. 2- Line and Ringer Connections
Fig. 3 - 54A (MD) Control Unit, Sche-
matic Showing Modification Us-
ing D-180117 Kit of Parts
Fig. 4- 54B Control Unit, Schematic
(e)
Replaceable Apparatus
(1) 54-Type Control Unit
• KS-16935, List 11 Cord (power)
• P-15E918 Cover Assembly
• RM-784064 Fuse (3/4-amp.)
ISS 5, SECTION 512-515-200
(f)
Tests and Adjustments
(1) When system is installed, or mainte-
nance is accomplished on any compo-
nent, test each station in the system for
proper operation of central office line pickup
and hold as well as the interphone features.
Make no adjustments on the 54-type con-
trol unit.
(2) Test monitor station output with one or
more remote stations being received at
full volume. Using volume control, lower
the output of the monitor loudspeaker. If
factory furnished volume control (100 ohm
potentiometer) does not lower audio output
sufficiently, a 1000-ohm P-25E020 potentiom-
eter may be substituted. Assure that volume
cannot be cut off completely. •
Note: Customer should be forewarned that
hands-free operation at the monitor station
will be affected by the increase in volume
control resistance and that it will be neces-
sary to increase volume when transmitting
for satisfactory results.
(3) In cases of radio frequency interference,
proceed as follows :
a. If a series one amplifier is used
(marked P-12E487 SER 1 or P-20F193
SER 1), place a KS-13814, List 1 capacitor
( 0.05 p.f) between terminals 3 and 4 of
the 2563C transformer in the control unit.
b. If interference is still encountered, pro-
ceed as follows:
• If interference is heard in the handset
when it is used for monitoring, with
neither push-to-talk bar depressed nor
the quieting relay actuated, connect an
additional KS-13814, List 1 (0.05 p.f)
capacitor between terminals C and 81
of the control unit terminal strip.
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