Garmin APOLLO GX SERIES, Service Manual

Page: 48 / 166

Garmin AT Rev --
7-10 GX Service Manual © 2004 Garmin AT
2. VDI Output (Not present on GX55/65)
Description:
The VDI output is a differential output intended for driving a meter movement with
a maximum load of 200 ohms.
Setup:
If the TST-10 test station is not available, connect a standard VDI (or equivalent
meter) to the Up/Down outputs.
Operation:
Select the VDI down, mid, and up outputs using the VDI Output page in test
mode.
Verification:
Verify the up/down indication as follows:
Down: meter full down
Mid: meter centered
Up: meter full up
Alternate:
Connect the unit to nominal input supply voltage. Connect a 200 ohm load
between the VDI+ Up and VDI+ Down outputs.
Verification:
Verify the differential output voltage between the VDI+ Up and VDI+ Down
outputs as follows:
Down: -150 mV ± 4 mVDC
Mid: 0 mV ± 2.0 mVDC
Up: +150 mV ± 4 mVDC
Verify the VDI+ Down output to ground is 2.05 volts ± 0.1 VDC.
3. TO/FROM Flag Output
Description:
The TO/FROM flag output is a differential output intended for driving a meter
movement with a maximum load of 200 ohms
Setup:
If the TST-10 test station is not available, connect a standard CDI with TO/FROM
flag (or equivalent meter) to the TO/FROM outputs.
Operation:
Select the Off, To, and From outputs using the To/From Flag page in test mode.
Verification:
Verify the TO/FROM indication as follows:
Off: Off indication
TO: TO indication
FROM: FROM indication
Alternate:
Connect the unit to nominal input supply voltage. Connect a 200 ohm load
between the To + and From + outputs.
Verification:
Verify the differential output voltage between the TO and FROM outputs as
follows:
Off: 0 mV ± 5 mVDC
TO: +250 mV ± 15 mVDC
FROM: -250 mV ± 15 mVDC
Verify the FROM+ output to ground is 2.05 volts ± 0.1 VDC.