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Faults and probable causes for them. Taken from "Practical Telephone Hand-book and Guide to Telephonic Exchange"
by T. S. Baldwin, M.A., written in the USA in 1902.


Possible Cause

Speech is received OK but transmission is weak.

Speaker too far away from transmitter.
Batteries weak or worn out.
Carbon packed.

Speech indistinct with grating or scratching noise.

Loose connection.
Battery too strong.
Zinc or carbon connection bad.

Bells ring feebly.

Bells need adjusting.
Bad connection.
Too many instruments on line.
Partial earth fault.
Poor adjustment of generator.
Weak generator.

Bells ring irregularly.

Loose connection.
Striker needs adjustment.

Bells will not ring.

Bad connection.
Broken wire.
Bells short-circuited.
Generator armature open circuit.

Receives and transmits ring feebly.

Broken line or ground wire.
Short circuit.

Bells ring OK to incoming ring but generator will not ring own bells.

Wire broken in generator.
Armature short-circuited.
Generator springs need adjustment.

Bells ring OK but generator rings other bells feebly.

Generator magnets weak.
Bad connection on generator.
Generator armature partially short-circuited.

No ring received or sent to line.

Wire broken.
Line short-circuited.

Bell rings without apparent cause.

Swinging connection to other lines.

Bell rings and generator rings other bells OK but you cannot talk.

Receiver cord broken.
Bad connections.
Gravity hook does not go to fully upward position.
Weak or worn out battery.
Transmitter dead.

Receiver weak.

Coil partly short-circuited.
Diaphragm bent or dirty.
Position of diaphragm not correct.
Permanent magnet weak.
Changes in temperature cause change to hard
rubber shell thus changing adjustments.
Receiver cord reversed.

Can hear but cannot be heard.

Transmitter circuit open or short circuited.

Call but get no answer.

Exchange relays open circuit or out of adjustment.
Open circuit lamp.
Short circuit in condenser.

Common battery transmitter speech received is good but transmission is poor.

Too much resistance in line circuit.
Diaphragm corroded.
Bad induction coil.
Low resistance transmitter.

Searching for a fault: When searching for a fault make a careful inspection as follows: First, examine the battery, replacing any zincs that may be unduly eaten away, and see that each cell has plenty of solution in it. Try all connecting screws or binding posts to see that none are loose. Next inspect the generator then check that the gravity switch works freely and all contacts make and break correctly. Inspect the ringer and check that the striker is not out of adjustment. Then inspect the transmitter looking for cracked diaphragm. Tap the transmitter lightly to make sure the granules are not packed. Next check the receiver to ensure there are no particles between the pole pieces and the diaphragm and that the diaphragm is not bent and that the spools are not loose on the pole pieces and that the cord is sound.

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