Figure 2-3.—Starter unit for 12-inch mercury-xenon searchlight

Operation To start the light, close the remote manual switch, then turn the starter counterclockwise on the rear of the starter unit. (See fig. 2-3.) Release the starter switch as soon as the lamp arcs. Be sure the starter switch returns to its previous position; otherwise, the higher current required to start the lamp may damage electrical components. Initially, the lamp burns only at about 25 percent of designed intensity. It takes 2 to 3 minutes to reach maximum brilliance. The light should not be elevated or depressed more than 10 degrees for extended periods of time because the life of the lamp is reduced considerably at extreme angles. Operate the shutters the same as you would the incandescent lamp shutters. To turn off the lamp, open the remote manual switch. Maintenance The 12-inch mercury-xenon arc searchlight should be inspected and checked monthly. All screws, especially those of the reflector clamps, focusing mount, and lamp support, should be examined for looseness. All screws and fastenings should be checked after ship's guns have been fired. Trunion and yoke bearings should be lubricated with grease; see the MRC for the type of grease. Replacement of the lamp must be performed as explained in the applicable manufacturer's manual, observing all precautions given. When the return action becomes sluggish, the shutter bearing and links should be lubricated. The lubricant should be used sparingly and should not be allowed to contact the envelope of the mercury-xenon lamp. Should the shutters remain sluggish, replace the shutter springs. The reflector and glass cover should be cleaned as required by the MRC. When considered necessary, the cover of the ballast box should be removed and the five resistors examined and tightened in their sockets. Wiring should be checked and terminal screws tightened as required. The packing glands at the cable entrances should be kept secure and watertight. Focusing is performed by means of a sliding plunger at the rear of the focusing box on top of the searchlight. Maintenance is basically the same for the manual-starting and automatic-starting, 12-inch, mercury-xenon searchlights. For detailed differences in the construction and operation of these two types, see the applicable manufacturer's manual. Electrical maintenance should be left to the electricians unless a member of the signal gang is qualified to do it by the engineer officer. Figure 2-3.—Starter unit for 12-inch mercury-xenon searchlight. 2-4