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D-039: AVIA Guide PAPI
10-3
Replacement of Red / Flashing IR LED Module
Place the power toggle switch on the Power Control Unit (PCU) control panel to the "OFF" position, see
Section 5-1. Disconnect the LHA cable at the PCU. For greatest safety power to the PCU should be
disconnected.
Remove the LHA weather cover by following the procedure in Section 10-1.
The red LED modules (meaning modules with both the red light LEDs and the flashing IR LEDs) are
located on the bottom row of the optical head assembly. Disconnect the cables to the module that is to be
replaced.
Remove the aluminum tape that is a seal around the red LED module that is being replaced. Mark the
position, relative to the optical head, of the red LED module, so that the replacement module can be placed
in the same position. Use a 3/32-inch hex wrench to loosen the six screws that hold the white LED module
to the optical head. Remove all of these screws. Hold on to the LED module while removing the screws.
Store the screws in a clean, dry place.
Separate the LED module from the optical head assembly. Remove the gasket (if there is a new gasket
available).
Obtain a replacement red LED module.
Replace the gasket.
Place the red LED module against the optical head assembly so that all six slots are aligned with their
corresponding screw holes. Replace the six socket head cap screws that hold the LED module to the
optical head assembly. Do not tighten yet. Move the LED module up and down until it is in the same
location as the LED module that was removed. Note that the location of the original LED module was
marked before the screws were loosened. Tighten these screws with a 3/32-inch hex wrench. Use
aluminum tape to seal around the red LED module.
Connect the cables.
orientation.
Note that the connector is keyed so that it cannot be inserted in an incorrect
Perform the checks in Section 9-2.1 to ensure that the module is functioning properly.
Replace the weather cover by reversing the steps in Section 10-1.
Tools Needed:
phillips screwdriver
3/32-inch hex wrench
Spare Part Needed:
red LED module, CH6399
gasket for LED module, CH6520
aluminum tape
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