Quantcast Sound-Powered Telephone Maintenance

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Replacing Handset Cords.-- To replace the cord
switchboard or switchbox line cutout switches will
on a sound-powered handset, you should use the
allow isolation of a faulty unit. For string circuits, you
following procedure:
should disconnect each set in sequence to isolate the
faulty unit.
1. Remove the faulty cord by unscrewing the
bushing and disconnecting the wires from the terminals.
LOSS OF SENSITIVITY.-- Loss of sensitivity, or
weakening of the transmission sound, is a gradual
2. Place the threaded bushing, washer, and
process and seldom is reported until the set becomes
grommet on the new cord.
practically inoperative. When a sound-powered
3. Insert the cord into the handset and connect the
telephone is in good condition electrically yet the sound
wires to the terminals.
is weak you should replace the transmitter unit. If this
4. Screw the bushing into the handset tightly to
procedure does not remedy the trouble, then you should
secure the cable.
replace the receiver units.
5. Test the set for proper operation.
To test a headset for loss of sensitivity, you should
Replacing Tinsel Cords.-- To replace a tinsel cord
depress the talk switch and blow into the transmitter. If
on a sound-powered telephone headset-chestset, you
the set is operating properly, you will hear a hissing
should use the following procedure:
noise in the receiver units. You should listen to one
receiver unit and then the other. In most cases, the loss
1. Open each unit connected to the cord that is to
in sensitivity is in the transmitter unit and might be
be replaced.
caused by a displacement of the armature from the exact
2. Before disconnecting the cord, make a diagram
center of the air gap between the pole pieces.
showing the color coding of the wires.
To test a handset for loss of sensitivity, you should
3. Disconnect both ends of the cord.
blow air into the transmitter. It is not necessary to press
4. Remove the screw that holds the tie cord, or
the talk switch because the transmitter and receiver are
untie the cord if it is secured to an eyelet.
permanently connected in parallel. If no sound is heard,
5. Unscrew the entrance bushing, if provided, and
either the transmitter or the receiver is defective. The
pull the cord through the port.
easiest method to determine which unit is defective is to
have someone talk into another phone on the circuit
6. Place the threaded entrance bushing, metal
while you listen to both the transmitter and receiver of
washer, and rubber gasket on the new cord and insert
the cord into the entrance port. The cord should be long
the handset. If the talker's voice is heard on one of the
units but not the other, you should replace the unit on
enough to allow slack after it is connected.
which the voice is not heard because it is defective. If
7. Secure the tie cord so that it takes all the strain
the talker's voice cannot be heard on either unit, and the
off the connections; otherwise the wires might be pulled
telephone circuit being used is known to be good, the
from their terminals.
fault may be traced to the line cord, switch, or internal
8. Connect the wires to the terminals.
handset circuits.
9. Screw the entrance bushing on the entrance port,
REPLACING CORDS.-- When replacing cords,
drawing the bushing up tightly to secure the cable and
you should always use prepared cords, if possible.
to seal the port.
Handset cords fitted with terminals at both ends are
10. Close the unit after all connections have been
available through standard stock. Tinsel cord cut to the
visually checked.
proper lengths and fitted with terminals for use with the
11. Test the set for proper operation.
various types of headset-chestset transmitter and
receiver units are also standard stock items. DCOP 1 1/2
If prepared cords are not available for repairing
headset-chestsets, you can make them from bulk tinsel
cord is used between the junction box and the plug on a
cord using the following procedure:
sound-powered headset-chestset.

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