Position Source 1 fail -Diagnosing the problem / how to use different GPS source in the interim

[Rocky_W]

Hello

I couple of weeks ago I got a caution: Position Source 1 Fail. The caution then disappeared and only reared it's ugly head again this weekend. However now it doesn't go away anymore and I keep losing GPS connection, but it is still intermittent.

This is not a new install. The system is from 2011. I am curious to know:

1. How likely is it that the fault sits within the sealed unit? (e.g. I need to replace the unit.)
2. Apart from physically checking the D-Sub connection / wires for damage, how would I best diagnose the problem?
3. I do have a Garmin 696 connected to the Skyview. Can I use the GPS signal from the 696 instead of the signal coming from the SV-GPS-250 and how would I set the system to use that?

Thanks

Roger

 

[Dynon]

1. Hard to say... They're pretty reliable, but it's not impossible for them to fail (as with any electronics)
2. Checking for physical connectivity is a good first step, but you might pair that up by wiggling wires while you're looking in the serial port menu, where you can see when the data flow is coming in or not from moment to moment. The RX counter (raw data coming ing) and Good Sentences (well-formatte data) are the two lines to pay attention to.
3. Yes. Connect to a serial port (sounds like it's already connected?), make sure the role is set to GPS X of your choosing, and also mak sure that you have the data rate set to "normal" under the 696's advanced NMEA setup menu.

 

[mikelupo]

Hello

I couple of weeks ago I got a caution: Position Source 1 Fail. The caution then disappeared and only reared it's ugly head again this weekend. However now it doesn't go away anymore and I keep losing GPS connection, but it is still intermittent.

This is not a new install. The system is from 2011. I am curious to know:

1. How likely is it that the fault sits within the sealed unit? (e.g. I need to replace the unit.)
2. Apart from physically checking the D-Sub connection / wires for damage, how would I best diagnose the problem?
3. I do have a Garmin 696 connected to the Skyview. Can I use the GPS signal from the 696 instead of the signal coming from the SV-GPS-250 and how would I set the system to use that?

Thanks

Roger

Realizing of course that this is a pretty old post, I wonder how you @Rocky_W resolved your issue?

I have a Dynon HDX install from 2024. Today I was flying and received that same message:
Position Source 1 fail, No ADS-B Out: GPS Lost
I have the SV-GPS-2020 wired up to a dual display HDX.
After I landed (have not flown again to try), I did cycle power everything including my 430w. There were no warnings.
Fingers crossed that it was a reception anomaly.
Thanks,
Mike

 

[GKC Aviation]

I have had several of the Garmin GPS antennas fail over the last year.
If you get the message, have a look at your 430W satellites page.
If you have no satellites all of a sudden, then your antenna is toast.
It starts intermittently, where all the sats drop off, but are fairly quickly regained, and it gets worse as time goes on.
Could also be the coax cable of course, but I have replaced four in the last 12 months for doing exactly this.

 

[mikelupo]

Hi @GKC Aviation, thank you for your reply.
This isn't the Garmin antenna that's involved (though I could at least confirm satellites that are visible there).
This has to do with the SV-GPS-2020 GPS antenna. That antenna wires directly to Serial Port 5 on the back of the HDX display unit. So it's either the HDX Internals, or the wires, or the antenna itself.

 

[maartenversteeg]

It probably would be better to talk about the SV-GPS-2020 as a receiver (in contrary to the Garmin which truly is just an antenna, so there is an analog signal traveling over the COAX cable). The Dynon module is not just an antenna but the whole GPS decoding happens in the module and out comes, in an RS232 serial datastream, the calculated position, time, satellites used, RDOP etc.

 

[GKC Aviation]

Oh, OK. I was thinking the 430W was providing your position source.
No worries

 

[GT3]

I also posted on another thread but I'm having the same issue, GPS Fix Status looks good even while the error is happening.
New install, dual screens, not impossible that it's wiring but not likely. I downloaded the log file if that helps, trying to get an answer from the forum before bothering the Tech Team... Also, I'm in Canada if that helps, just on the edge of the border but not in great range for US ADSB antennas.

 

[jakej]

I also posted on another thread but I'm having the same issue, GPS Fix Status looks good even while the error is happening.
New install, dual screens, not impossible that it's wiring but not likely. I downloaded the log file if that helps, trying to get an answer from the forum before bothering the Tech Team... Also, I'm in Canada if that helps, just on the edge of the border but not in great range for US ADSB antennas.

GT3 -
I have seen a similar issue in the past & in 1 case is was caused by too much ‘handling’ of the 2020 before install. The antenna is supplied with a reasonably long ‘tail’ of 4 core twisted 22g wire resulting in a fair bit of weight hanging at the bottom of the antenna. That weight can cause the wire connection, at the base, to be fractured with excessive/casual rough handling before install- I don’t know of a test for this other than ‘borrowing’ another unit.
My ‘fix’ to mitigate the chance of this happening is to cut the bundle (then adding a 4 pin connector during completion of the install) about 12” from the antenna as soon as I receive them ( I’ve done a lot of Dynon installs on Experimental Aircraft).
You don’t say where your antenna is mounted - if it is forward of firewall (under the cowl) then that, most likely, will eventually cause a failure of the 2020 antenna. How do I know ? I had mine mounted there for a few years & figured it was ok - then it too failed now I’m a believer in NOT mounting anywhere near engine heat - & a little poorer.
Others have had similar issues so your feedback as to the cause/solution would be appreciated by others, I’m sure..

 

[GT3]

Thanks for the intel Jake, all valid possibilities but they don’t apply in my case. Antenna is mounted on the top of the aluminum fuselage, harness has a good service loop but I like your connector idea.