Keep all electrical contacts clean and bright.
on which is hinged, to provide access for relamping or
cleaning.
Check electrical leads daily an replace them as
XENON AND MERCURY-XENON ARC
soon as defects appear.
LAMPS.-- Mercuty-xenon gas-filled arc lamps operate
Lubricate trunnion bearings and stanchion
on 60-hertz alternating current or, with some change in
sockets according to PMS requirements.
the starter circuit and ballast resistor, on 400-hertz
alternating current. The light produces a concentrated
Adjust the two shutter stop screws, located next to
arc of intense brilliance, which provides sharp focusing.
the handles to compensate for wear in the leather
Searchlights with mercury-xenon arc lamps are
bumpers. These bumpers cushion the shock of the
normally used for signaling, but they may also be used
shutter vanes closing. The bumpers should just touch
for illumination. The 12-inch mercury-xenon arc
the stop adjustment when the vanes are closed to prevent
searchlight includes the following parts:
the shaft from twisting. Check the shutter vanes
1. 1,000-watt lamp
frequently to ensure that all screws are tight.
2. Drum
Clean the reflector weekly or more often to remove
dust. Remove salt spray from the lens and reflector as
3. Back dome
necessary. You should use the following instructions to
4. Signaling shutter
clean the reflector:
5. Mounting yoke
Ensure that the surface is cool. Touching a hot
6. Focusing device
surface with your bare skin can result in a serious
7. Automatic lamp starting circuit (attached to the
burn.
lower part of the drum)
Use standard Navy brightwork polish.
8. Screening hood with various colored falters
Use a soft, lint-free cloth, or clean the reflector
The wiring diagram of the 12-inch mercury-xenon
in accordance with the PMS MRC.
arc searchlight is shown in figure 4-32.
Use a radial motion from the center to the rim of
Automatic Starting Circuit.-- A high-voltage
the reflector. Do not use a circular motion.
pulse type of circuit is used When the searchlight is
Do not paint bolts, locking nuts, and other parts
turned on, the booster transformer supplies 130 volts to
the primary of the transformer, which in turn provides a
necessary for access to the interior or over
series of pulses of about 50,000 volts generated by
nameplate data. Keep oiling holes free of
high-frequency discharges through a spark gap.
paint.
When the main arc in the lamp is established, the
Only qualified Electrician's Mates should replace
voltage in the primary of the transformer drops to 65
the lamp or adjust the focusing unless a member of the
volts. This voltage is not high enough to cause the
signal gang is qualified. The light source must be at the
secondary voltage of the transformer to break down the
focusing point of the reflector for minimum beam
spark gap. Thus, the high-voltage pulses to the lamp
spread and maximum intensity. Some types of 12-inch
automatically y stop.
incandescent searchlights are provided with focusing
Ballast Circuit.-- Five parallel-connected resistors
adjustment screws. Other types can be adjusted by
are connected in series with the lamp as shown in figure
loosening the screws that hold the lamp-socket support
4-32. These resistors limit the current at starting and
plate in position. The entire socket assembly can be
during operation, supplying the correct electrical values
moved toward or away from the reflector until the
to the lamp.
beam has a minimum diameter at a distance of 100
feet or more from the light. The screws must be
MAINTENANCE ON 8- AND 12-INCH
retightened after the final adjustment. The diameter of
SEARCHLIGHTS.-- These searchlights are main-
the beam must be checked with the rear door clamped
tained by following the same practice that relates to all
tightly shut.
electrical and mechanical equipment:
4-34
