![background image](http://html1.mh-extra.com/html/federal-signal-corporation/224xsthi/224xsthi_installation-and-service-instructions-manual_3813590005.webp)
-4-
5.
Loosen the retaining ring fastening screws approximately 1/2-turn. The retaining
ring can then be turned counterclockwise approximately 1/2-turn. The retaining ring can then be
lifted free of the unit. The interior lens can now be removed from the unit.
6.
Grasp the flash tube by its base and pull it out of the socket, using a gentle
“rocking” motion. Install new flash tube, ensuring that the flash tube is fully seated in the socket.
7.
Reinstall interior lens.
8.
Before replacing the dome, ensure that the gasket is properly seated and shows no
signs of cracking or other deterioration. Replace the gasket if it is damaged or shows signs of
deterioration.
9.
Place the dome over the base, aligning the recesses inside the dome lip with the
four pins on the base. Push down on the dome and turn clockwise until it locks in place [approxi-
mately 3/4-inch (19mm)].
10.
Replace the screw into the bottom of the dome.
11.
Test the light for proper operation.
B.
Circuit Board Replacement.
High voltages are present inside the light assembly. Wait at least 5 minutes after
shutting off the power before servicing unit.
1.
Disconnect power.
2.
Remove the setscrew located at the bottom of the dome.
3.
Grasp the top of the dome and push down while turning the dome counterclockwise
approximately 3/4-inch (19mm).
4.
Gently lift dome away. Ensure that the gasket between the dome and base is not
lost.
5.
Loosen the retaining ring fastening screws approximately _ turn. The retaining
ring can then be turned counterclockwise approximately _ inch (13mm), allowing the retaining to be
lifted free of the unit. The interior lens can now be removed from the unit.
6.
Remove and retain the screws and heat sink clip, which secures the power supply
circuit board to its mounting plate. Remove the power connector(s) from the P.C.B. Since some
strobes are polarity sensitive, connect matching colored wires together.
7.
Secure the new circuit board to the mounting plate with the previously removed
screws and reattach heat sink clip.
8.
Install flash tube as described in Section III.A. (Flash Tube Replacement). Ensure
that the flash tube is fully seated in the socket.
9.
Reinstall interior lens.
10.
Before replacing the dome, ensure that the gasket is property seated and shows no
signs of cracking or other deterioration. Replace the gasket if it is damaged or shows signs of
deterioration. Replace the gasket if it is damaged or shows signs of deterioration.
11.
Place the dome over the base, aligning the recesses inside the dome lip with the
four pins on the base. Push down on the dome and turn clockwise until it locks in place [approxi-
mately 3.4-inch (19mm)].