SECTION 8 SENSITIVITY ADJUSTMENT (cont) - TM-55-1930-209-14P-17

SECTION 8 SENSITIVITY ADJUSTMENT (cont) - TM-55-1930-209-14P-17_1021

TM-55-1930-209-14P-17 Water Purification Barges (NSN 1930-01-234-2165) Miscellaneous Equipment Dayroom Workshop Access and Sanitation Systems Manual
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8.8 Remove an individual module smoke as follows: a. Loosen the two thumb screws top and bottom. Screws are captive type and do not come all the way out. b. Grasp the two screws and pull towards you. c. The module will slide out, revealing a printed circuit board with two potentiometers, one along the edge of the metal framework and one closer to the center section of the board. The potentiometer near the edge of the board is sealed at the factory and represents the standardization calibration of the device made in the UL qualified smoke detector chamber. CAUTION Under no circumstances must be factory adjusted potentiometer be changed. This is a supercritical adjustment made under very controlled conditions and can NEVER be re-established in the field. 8.9 Make adjustments with a non-metallic, narrow screwdriver (TV front-end tuning wand). Adjust the potentiometer (with a single turn positive stop in each direction). As shipped, it will be turned all the way counterclockwise. Turn it about halfway clockwise and return the module to the housing. 8.10 Removal of the module produces a trouble signal. Re-inserting the module will eliminate the trouble signal and will produce an immediate alarm signal because the photoelectric cell in the detector has been exposed to ambient light conditions while being adjusted. CAUTION Do not attempt to reset the panel immediately since the photoelectric cell takes some time to restore. Wait approximately five minutes and then operate the switch. The panel should now reset completely. (If you are doing more than one adjustment or adjusting more than one module, it is advisable to make all the adjustments first and then reset five minutes after the reinsertion of the last module. 8.11 When re-inserting the module, it is essential that the assembly seats firmly and the thumb screws are turned down tightly to produce a positive air seal under the module front. Occasionally, the use of a non-petroleum lubricant will improve the sealing qualities. 8.12 The modules are equipped with light brown sealing gaskets to prevent moisture from being drawn into the cabinet, causing false alarms. 8-2

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