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 TM 55-1905-220-14-9
4-48. ALARM SWITCHBOARD - MAINTENANCE INSTRUCITONS (Continued).
CAUTION
No oil of any kind should be used anywhere on the two line units or the
assemblies of which these units are composed. These units are energized
with 120V A.C. and depend upon the minimum electrical clearances for
insulation. Oil used anywhere on the assemblies in very likely to break down
these clearances and cause flashovers and short circuits.
(3)
Alarm Panel.
(a) The alarm panel door should be opened periodically and all electrical connections checked for
proper tightness. Wiring should be checked a the same time for chafing.
(b) All lamps should be kept in operating condition. Defective bulbs should be replaced
immediately upon discovery. All lamps except the type NE 79 (Neon) "Test Light", PL1, are Type VG-7 (Neon)
lamps. Sockets for these lamps should be checked occasionally to see that the socket contacts are clean and
making good contact with the lamps. The trouble buzzer, Z, should be tested periodically and kept in proper
adjustment. All securing screws should be kept tight.
g. The following is a index of the maintenance instructions.
DESCRIPTION
PARAGRAPH
Alarm Switchboard
2-Line Alarm Panel
4-1237/(4-1238 blank)
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