Fig. 108.
Inspect for contact of lightning-arrester carbons: a piece of writing-paper should pass between them easily. See that the ends of the line and ground wires do not touch any other part after passing through the binding-posts.
Disconnect the line and ground wires. If the bell rings now, (1. Short circuit on line) is clearly indicated, but if it does not ring and still turns hard, (3. Short circuit in phone) is indicated.
If the handle does not turn hard, the operator takes up (2. Mechanical trouble in the bell) and sees that the striker is not bound by the metallic cap over it or by the wood of the box, also that the armature can be moved by hand and that the striker will touch the gongs when the armature is so moved. The first trouble can be remedied; the others should be reported.
(4. Open circuit in the phone). Open the magneto box, see that contact is made between shaft and spring at U and between the springs at V when the handle is turned. The last may fail because the shaft is caught at some place, as where it enters the box or the collar on the shaft may have slipped or the springs may be bent. The spring at U may be held against the end of the shaft with a pencil, during a test, to insure good contact. A spark seen at U or V indicates poor contact. If the operator cannot easily correct these faults, he should report as nearly as practicable what trouble he found.
Test for (5. Magneto does not generate) by moistening the tips of the fingers and touch terminals of magneto. Turn the handles, and if no shock is felt, a failure to generate is indicated.
2d. Bell is not rung by distant magneto.
Analysis:
1. Home phone out of order.
2. Distant phone out of order.
3. Line out of order.
Operator's test:
(a) Test for (1. Home phone out of order) by detaching the line and ground wires and turning the handle.
(b) Test for (2. Distant phone out of order) at the distant phone in a manner entirely similar to (1. Home phone out of order).
(c) See expert's test for line troubles.
Can hear but cannot be heard.
Analysis: