Bell System Practices 1A Installation And Maintenance page 3

• Transmitting volume is preset at the time
of manufacture and should not be changed.
• Make sure that all features of any key
plan when used with the IA speakerphone
system operate properly.
• The IA speakerphone system should be
able to transfer from a regular call using
the handset to the speakerphone and back
to the handset.
• The OFF button should restore the circuit
to normal and all features of any key plan
should be returned to normal.
2.08
Fluorescent lights, transformers, motors,
or other similar apparatus on the cus-
tomer's premises may cause an inductive noise in
the loudspeaker. Grounding the amplifier chassis
may eliminate this noise. In certain areas local
ordinances may not permit grounding. Be guided
by local instructions.
2.09
In some cases the amplifier may pick up an
inductive hum from 60-cycle ac power sup-
ply located near the IA speakerphone system. A
special modified RC3 receiver is substituted for
the regular modified VI receiver to correct this~
See the section entitled IA Speakerphone System,
Maintenance.
2.10
Where radio interference is experienced
in the telephone set, a suppressor may be
installed. See section entitled Radio Signal Sup-
pression in Telephone Sets.
3. MAINTENANCE
592-Type Telephone Set
3.01
In maintaining the 592-type telephone set,
refer to the appropriate section for those
items that are common to all 500-type sets.
3.02
By visual means inspect and, if found
defective, replace:
• Window-strip assembly
• Volume-control knob
• Key buttons
ISS. B, SECTION S 12-61 0-200CA
3.03
Clean exterior of. set with a soft, water-
dampened cloth. Check wiring for loose
connections and for obstructions to movable parts.
3.04
With the cover assembled, the set shall
meet the following requirements:
• The key buttons shall be free and shall
return to their unoperated positions after
being depressed fully.
• The volume-control knob shall be free to
rotate over its entire range of operation.
A failure of either of these requirements usually
can be corrected by shifting the key assembly; if
this does not clear the trouble, replace the set.
3.05
The contacts that make on operating the
ON and OFF keys shall have a perceptible
follow. If defective:
• Adjust springs by making bends at spring
pile-up with a 363 tool.
• Clean contacts by using 265C tool with
clean burnisher blade.
3.06
The flanged edge of the. soft neoprene
gasket around the 655A transmitter (VI-
type receiver) shall not be cut or deformed.
Replace entire transmitter in case of defect.
R ~ Where the regulaT 655A tTansmitter
R
~ (Vl-type receiver') is tr'oubled by induc-
;, tive inteTference from power source, the
D
trouble may be remedied by using a
658A tr'ansmitter (HC3 r'eceiver with a
cold-Tolled steel s7:deld). These tmns-
mitteTs are completely interchangeable
b'ut available only on a maintenance
basis by special order'.
4. 6S6A TRANSMITTER
4.01
When performing maintenance on 656A
transmitter, proceed as follows:
• Replace chipped or cracked housing.
• Replace any soiled or missing friction pads.
• Clean exterior of transmitter with a soft,
water-dampened cloth.
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