Northern Airborne Technology LD12-002 - Manual (Page 8)

LD12-002 LED Dimmer
SM85 Installation and Operation Manual
Section 2 Rev: 1.00 Issue 1 Page 2-3
ENG-FORM: 805-0121.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.4 Lighting Mode Switch
The normal installation of the LD12-002 assumes the installation of a remote momentary SPDT centre-off
toggle switch, used to select from the following modes:
MODE SWITCH POSITION FUNCTION
DIM Selects night flying LED levels. See section 2.5
NORM Selects day flying LED levels (full brightness).
TEST Tests functionality of all LEDs. All LEDs ON (full brightness).
The centre-off position of the switch should correspond to the NORM position.
The mode switch should be spring loaded in the TEST position so that it will return to the NORM position
when released. Alternatively, the DIM function can be selected by a separate switch, or tied into another
switch function, and the LED test can be activated by a momentary pushbutton switch.
The DIM position can also have a level control connected in series with the switch, to permit local
adjustment of the night flying LED level. The switch may also be integral with the level control to
conserve panel space.
2.4.5 Optional Dimmer Adjustment
Inserting a 10 k
Ω, 1/2 W linear taper potentiometer between the dimmer input and ground will allow
external adjustment of the dimming voltage. If using an external adjustment, ensure that the internal
trimpot is set for minimum voltage output (rotated fully ccw).
2.4.6 Optional Emergency Bypass Switch
An optional external single-pole single-throw toggle switch can be installed to route an external voltage to
the LEDs if the dimmer should fail.
2.4.7 Post-Installation Checks
Before the unit is mounted, make all functional tests and trimpot adjustments. Be sure the harness has
enough clearance to permit the unit to be pulled out for re-adjustment, if needed later.
2.4.7.1 Voltage/Resistance Checks
Do not attach the LD12-002 until the following conditions are met.
Check the following:
a) Check P1 pin <1> for +28 Vdc relative to ground.
b) Check P1 pin <34> for continuity to ground (less than 0.5
Ω).
c) Check J1 pin<2> for 28 Vdc LED power from lighting bus.
d) Ensure that no short circuits exist on any line (Lamp HI to lamp LO or to ground).