Garmin APOLLO GX SERIES Service Manual page 49

Garmin AT
4. Annunciator Outputs
The GX50/60 includes six annunciator outputs intended for turning incandescent
Description:
lamps on/off. The six outputs are MSG, PTK, GPS, OBS/HLD, APPRCH, and
ACTIVE.
The GX55/65 includes two annunciator outputs intended for turning incandescent
lamps on/off. The two outputs are MSG and PTK. These are open collector
outputs capable of sinking 400 mA.
If the TST-10 test station is not available, connect the annunciator outputs to
Setup:
incandescent lamps, and the other side of the lamps to aircraft supply voltage
(Vac).
Using the Lamp Outputs page in test mode, select on and off for each of the six
Operation:
outputs by rotating the small knob.
Verify that the lamps connected turn on and off as indicated on the GX display.
Verification:
Connect the unit to nominal input supply voltage. Connect a 400 mA load
Alternate:
between each of the annunciator outputs and aircraft supply voltage (Vac). (If
Vac = 13.6 volts, then a load resistor of 33 ohms can be used.)
The load resistor is computed by:
(Vac - Vcesat) / Ioad = (13.6 volts - 1 volt) / 400 mA = 31.5 ohms.
(Rounding to 33 ohms is OK)
Verify the output voltage of the six annunciator outputs as follows:
Verification:
Lamp on:
Lamp off:
5. Hold Input (Not present on GX55/65)
The waypoint sequencing hold input is a discrete input intended for connection to
Description:
a momentary button to aircraft ground.
If the TST-10 test station is not available, connect the unit to nominal input supply
Setup:
and connect a momentary switch from the Hold input to ground.
Using the Lamp Outputs page in test mode, rotate the small knob to select the
Operation:
Push WPT SEQ To Toggle OBS/HLD page. Press the Wpt Seq momentary
switch several times.
Verify the OBS/HLD annunciator and the GX display change when pressing the
Verification:
momentary switch.
© 2004 Garmin AT
1.0 VDC max
Vac ± 0.1 VDC min
GX Service Manual
Rev --
7-11