1. Turn off power to the system.
2. Remove and inspect sampling tube filters.
3. If filters are heavily coated with dirt, replace them with
new filters. If they are not heavily coated, use a vacuum
cleaner or compressed air nozzle to remove dust, then
install the filters.
4. Remove the detector from the housing. (See Figure 8.)
Photo Units
5. Remove the detector cover by inserting a small-bladed
screwdriver into the slot located approximately 90
degrees from the MOD400 test jack. Rotate the cover
counterclockwise to remove it. See Figure 10.
6. Lift the screen from the photo chamber. Vacuum the
screen and cover before using clean, compressed air to
loosen and blow out any remaining debris (replacement
screens are available, part no. RS24).
7. Vacuum the photo chamber. Then, use clean compressed
air to blow it clean.
8. Replace the screen by aligning the arrow on top with the
test slot in the base of the detector. Press the screen into
place. It should fit tightly in the chamber.
Ion Units
9. See Figure 11. Remove the cover and screen assembly
by depressing the three lock prongs on the top of the
cover and rotating the cover counterclockwise. The
CRT400 Cover Removal Tool makes cover removal
easier.
10. Carefully pull the screen out of the cover.
11. Clean the screen thoroughly with a soft brush or vacu-
um cleaner (replacement screens, part no. RS14).
12. Brush or vacuum the inside of the cover. The cover
may then be blown out using clean compressed air.
13. Vacuum the sensing chamber before using clean,
compressed air to loosen and blow out any remaining
debris.
14. Press the screen back into the cover.
15. Replace the detector cover on the sensing chamber.
Rotate it clockwise to lock it in place.
Both Types Of Units
16. Reinstall the detector in its housing.
17. Restore system power.
18. Put detector into alarm using appropriate method
described in STEP 7.
Perform Detector Check
19. Notify the proper authorities that testing has been
completed and the smoke detector system is back in oper-
ation.
20. Other checks that should be made during maintenance
procedures:
— Holes or cracks in duct work near vicinity of detec-
tor.
— Air leaks where detector housing or sampling tubes
are attached to duct.
— Dust accumulations in or on sampling tubes.
— Wiring terminal screw tightness.
Figure 10. Photo head exploded view:
LOCK PRONG
REMOVABLE SCREEN
(P/N RS14)
REMOVABLE
COVER
FOR
CLEANING
SENSING CHAMBER
H0246-00
Figure 11. Ion head, exploded view:
REMOVABLE HEAD COVER
CLEANABLE SCREEN
HEAD COVER
REMOVAL SLOT
TEST SLOT
VANED CHAMBER
P/N RS24 (W/O THERMAL)
H0261-00
D500-07-00
9
I56-432-11R
