Garmin AT
Rev --
© 2004 Garmin AT
GX Service Manual
7-13
8. Valid Flag Outputs
Description:
The GX50/60 includes two low-level valid flag outputs - NAV valid and VDI valid.
The GX55/65 includes one low-level valid flag output - NAV valid. These are
differential outputs intended for driving a meter movement with a maximum load
of 200 ohms.
Setup:
If the TST-10 test station is not available, connect standard NAV and VDI valid
flags (or equivalent meters) to the valid flag outputs.
Operation:
Using the Valid Flag Pages page in test mode, rotate the small knob to select the
two valid flag outputs, each flagged and not flagged.
Verification:
Verify indication as follows:
Flagged: Flagged
indication
Not flagged:
Valid indication
Alternate:
Connect the unit to nominal input supply voltage. Connect a 200 ohm load
between each of the low-level valid flag outputs to ground.
Verification:
Verify the differential output voltage between the NAV+ Valid and NAV/VDI Valid
flag ground and VDI+ Valid and NAV/VDI Valid flag ground outputs as follows:
Off (Flagged):
0 mV ± 5 mVDC
On (Not flagged): +290 mV ± 15 mVDC
9. Serial Ports
Description:
The GX50/60 includes two serial ports. The GX55/65 includes one serial port.
Setup:
If the TST-10 test station is not available, connect the unit to nominal input supply
voltage and connect the TxD output to the RxD input.
Operation:
Using the Serial Port Test page in test mode, rotate the small knob to select the
two serial ports.
Verification:
Verify both serial ports pass the port test
10. GPS Antenna Voltage
Description:
The GPS antenna is an active device receiving power from the GPS receiver
PCB.
Setup:
If the TST-10 test station is not available, connect a 100 ohm load to the GPS
BNC connector at the back of the GX unit.
Operation:
With power to the unit on, measure the voltages at the GPS antenna BNC
connector on the back of the unit.
Verification:
Verify that the output voltage at the rear GPS BNC connector, with a 100 ohm
load connected to ground, is >4.6 VDC.
Summary of Contents for APOLLO GX SERIES
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