Northern Airborne Technology LD12 - Manual (Page 13)

SM15 Rev. 4.00 LD12 Lamp Dimmer Manual
Nov 21, 2003 Page 2-3
ENG-FORM: 805-0104.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.3.6 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, make sure internal trimpot is set for minimum voltage output (rotated fully
counterclockwise).
2.3.7
Optional Emergency Bypass Switch
This is an optional external SPST toggle switch; it can be used to route an external
voltage to the lamps if the dimmer should fail.
2.3.8 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.
2.3.8.1 Voltage/Resistance Checks
Do not attach the LD12 until these conditions are met.
a)
At the airframe connector, check P1 pin 1 for +28 VDC relative to ground and
pin 34 for continuity to ground (below 0.5 ohms).
b)
Ensure that no short circuits exist on any lamp line (lamp hi to lamp lo or to
ground), and that no press-to test lamp holders have been used. These can
cause the lamp line(s) to be shorted to ground, which may damage the internal
circuitry of the LD12.
2.3.8.2 System
Checks
a) Install the LD12 and power up the ship’s systems. Select the TEST position on
the dimmer switch and check that all lamps are functioning.
b)
Select the BRIGHT position on the dimmer switch; lamps that are activated
should be fully illuminated.
c)
Select the DIM position on the dimmer switch and adjust the dimmer pot; the
active lamps should track the dimmer pot.
d)
Make sure unit is securely fastened and that the connector locks are correctly
mated before any flight is attempted.