MAINTENANCE 147 



Receiver cap should be fairly tight. 



Bent, dented, or rusted diaphragm of receiver should be replaced. 



Dirt on or under diaphragm should be removed. 



All wiring inside of instrument should be in good condition. 



Generator should ring the bell clearly with switch open. 



Generator crank should not bind when turned. When binding comes on gradually 

 some operators do not know the difference. It is caused by grounds or lack of oil. 

 Short circuits may cause either gradual or sudden binding of the generator. 



Contacts of the switch-hook should be clean. 



Generator should be fastened in the instrument securely. 



Contact points of the generator (left side) should make good connection. 



All screws inside the instrument should be tight. 



Adjusting nuts on bell 'should be tight. 



Resistance of all ringer coils should be the same. 



Nuts on protector should be tight. 



Protector blocks should 'be free from soot, smoke, or dust. 



Protector blocks should be metal, not carbon. 



Protector should be connected as shown in Fig. 45. 



Protector should be screwed (not nailed) to wall. 



!Micas should not be cracked or otherwise injured. 



Nuts on cut-off switch should be tight (if switches are installed). 



Blades of cut-off switch should make good contact with springs. 



Instrument should be screwed (not nailed) to wall. 



Ground rod should be standard. 



Ground wire should be soldered k> ground rod. 



Ground rod should be driven into ground within 8 in. of its full length. 



Line wires and inside wires should be soldered where they connect with each 

 other. 



Splices in insulated wire should be taped. 



Entering wires should run through circular loom or porcelain tubes. 



All wiring outside should be insulated properly from buildings by being attached 

 to knobs or insulators. 



Insulation should be good on all inside wires. 



All battery connections should be tight. 



Transmitter arm should be screwed tightly to box. 



Transmitter arm should be tight enough to hold it in proper position. 



All nuts and screws on transmitter should be tight. 



Metal parts of battery should not touch each other. 



Are batteries good? Should be three. 



The following instructions may be of value to officers who have occasion to test 

 instruments and hunt for faults : 



(1) Test the batteries with the battery gauge to determine whether or not they 

 are exhausted. 



(2) Clean all battery connections, post terminals, and ends of all connecting 

 wires that have become corroded. See to it that all battery terminals, nuts, or screws 

 on the binding-posts are thoroughly tightened. 



(3) Follow up the wires from the battery to the instrument. Repair them where 

 damaged, and staple if they have become loosened. 



(4) Tighten all loose connections 1 in the telephone instrument. 



(5) See to it that the switch-hooks work freely. Note carefully that a good con- 

 nection between the contact springs of the receiver hook is made when the receiver 

 is off the hook and the lever is up, and that the contact is broken when the receiver 



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