"position unknown"

[anthonyxritchie]

I have a skyview display that's fed a GPS signal from a Garmin GTN 650. I have about 15 hours with this this setup but just recently during a fuel stop when I started back up, the map page reads "position unknown." and has ever since (the rest of that flight and the next one, about 2+ flight hours). The GTN appears to be working normally and in the info for the the Dynon display it seems to show that its receiving a GPS position from the Garmin. Plus the Dynon ads-b transponder is using the same GPS source and is also working fine.

Any ideas why the map is unable to show the airplanes position on the map or what other troubleshooting steps to take?

 

[skysailor]

Take a look at the serial port where the position data comes from the Garmin. Make sure it is showing traffic on the port and no errors. Do you by chance have a Dynon GPS antenna (even the VFR only one)? If so check the assignment of the serial ports and make sure your Dynon shows POS1 for the port receiving the ADSB position data from the Garmin.

 

[anthonyxritchie]

Well this is interesting: I don’t have anything set up in the serial set up for position data. Port 5 has “dynon sv-gps-250” for “pos 1” (a device that I don’t have). the arinc-429 is set to receive nav 1 on input 2 and nothing on input 1.

I had a shop set this up so I’m not up to scratch on how this is supposed to work and seems weird if these internal settings would be working fine and then just stop during a fuel stop.

I do not have a second gps receiver.

 

[SV_Classic]

If it was already working I'd also suggest checking all of the connectors at each of the Dynon components.

Good luck with it

 

[anthonyxritchie]

Update on this. Everything is tight and looks like it always has but the gps position hasn’t come back up. Now the map screen stays blank with a red X and it says “no GPS position”

Any ideas on where to start troubleshooting this would be appreciated.

 

[swatson999]

Update on this. Everything is tight and looks like it always has but the gps position hasn’t come back up. Now the map screen stays blank with a red X and it says “no GPS position”

Any ideas on where to start troubleshooting this would be appreciated.

Have you gone through the Installation Manual section on the ARINC connections and configurations?

 

[SV_Classic]

Update on this. Everything is tight and looks like it always has but the gps position hasn’t come back up. Now the map screen stays blank with a red X and it says “no GPS position”

Any ideas on where to start troubleshooting this would be appreciated.

You said earlier that you had a shop set it up. I'd start with a call to the shop to see if they're willing to help. There's always the chance if they screwed it up that they won't be able to fix it but I'd at least call to see what they have to say.

Depending on how much time you have and, since you've already looked into the serial port assignments, you could troubleshoot each of the serial assignments as swatson suggested. Maybe configuring it from scratch will get the GPS signal to recover but it's weird that it worked and now it doesn't. I wouldn't guess it's configuration related but anything's possible I guess.

If I had to throw a w.a.g. out there I'd guess there's a soldered connection that has had enough after 15 hours and broke.

 

[CanardMulti]

Some basic thoughts on trouble shooting this situation:

1. Something that did work does not function correctly any more. A very useful starting place is determining with relative certainty whether the fault lies within your Skyview unit or with its peripherals.

2. It sounds like Skyview's preferred serial input for GPS, #5, is not in use. If so:

3. Time is money. If you can get the use of a Dynon GPS unit to temporarily connect to serial port #5, you will most likely quickly get an answer to #1 above. You will have to follow the simple process in the installation manual to tell Skyview it is there.

Even a GPS 250 will serve the purpose. If the shop who did your set up does not have one (as the result of a customer's upgrade to a GPS 2020 for ADSB-out compliance) a used 'working when removed' unit is likely available from someone who had to upgrade to a GPS 2020 for not much more than $100. How many hours of expensive avionics shop time - or your time - is that worth?

Worst case, a new one from Dynon costs $256 full retail. You could even later permanently install it as a backup.

Good luck!

Ken

 

[anthonyxritchie]

This is all helpful (I didn't realize the GPS receiver was so cheap. that might be a worthwhile backup).

So far I've eliminated wire continuity as a culprit. All 7 wires between the GPS and the ARNIC are continuous (and also are not shorting to ground).

The ARNIC config page I CHANGED and set GPS 1 in input 1 (previously input 1 was empty) I left NAV 1 in input 2. That apparently brought the map back up (as opposed to the black screen with the red X) and will display flight plan routes from the Garmin.

A couple things are not very clear still.

1. There's settings on the ARNIC page that are shown in the manual but I don't see in under SETUP>SYSTEM SETUP>ARNIC-429 in. The manual specifies "EFIS Format 2" for in 1 and "GAMA format 2" for out (I'm supposing these are synonymous with "high") . The other missing one is "SDI: Common"

2. Do any serial port settings need to be configured. It looks like the SV 250 is in port 5 by default and it seems like I would need to get some position info from the serial ports but the manual doesn't mention configuring the serial ports. (also there's no preset for a Garmin GTN as an option for the serial ports)

Otherwise, as far as I can tell, all the internal settings are consistent with the manual.

I do have a call into Dynon to see if they can help out. The shop that did the work was about 10 years ago (that's how long it took to finish my build), they are not local and I was underwhelmed (to say the least) with their service and professionalism so I'm going to avoid going to them for help if I can.

 

[maartenversteeg]

The term "EFIS Format 2" and "GAMA Format 2" appear under the heading Garmin settings . So these you probably would have to search in the Garmin setup. Although I don't have a Garmin 6XX/7XX, a similar issue appears in the Garmin 430

 

[swatson999]

Are you looking in
Third-Party Device Connection and Configuration Reference Guide
?

 

[anthonyxritchie]

Well newer update is that Dynon called me back and we talked though all the settings that needed to be checked. They were all correct. (I did realize the thing of the GTN setting while the phone call but didn't change anything)

While were on the phone I pulled the plane back outside (to get GPS reception) knowing that it wouldn't work because we didn't change anything and... it worked... so I guess it's just one of those things.

I am now sold on getting the Dynon GPS receiver for redundancy (and battery backup navigation in case of electrical failure).

 

[swatson999]

FWIW, my Dynon GPS-2020 gets really good signal reception in the hangar (bifold doors up), but the GNS-430W I have won't see squat until it's pulled out of the hangar.

knowing that it wouldn't work because we didn't change anything

but you *did* change something...

The ARNIC config page I CHANGED and set GPS 1 in input 1 (previously input 1 was empty) I left NAV 1 in input 2.

(Just to note...it's ARINC, not ARNIC . Aeronautical Radio, Inc.).

 

[SV_Classic]

@anthonyxritchie glad to hear you were able to work through it and get it up and running again. Thanks for coming back to post the follow up

 

[airguy]

FWIW, my Dynon GPS-2020 gets really good signal reception in the hangar (bifold doors up), but the GNS-430W I have won't see squat until it's pulled out of the hangar.

Same - with my Avidyne 440, it won't get a position in the hangar but my Skyview will.

 

[anthonyxritchie]

but you *did* change something...

No I had changed that way earlier. This was my 3rd or 4th time pulling it out and checking it with no luck (I had even gone for a flight after I had made that change).

I had already planned to add the Dynon ADS-B in system so I'll probably throw in the GPS antenna whenever I get to that.

 

[swatson999]

So since it seems to be working now, I guess the best course of action is to go fly until it fails again (if it ever does). If it *does* fail, I'd suggest the following things:
Don't touch or change anything
Immediately dump a diagnostic file, the user logs, and all configuration files onto a memory stick.
Get screenshots of all the appropriate menu pages on the Skyview (debug data, serial port data, etc.) and the Garmin (all the configuration pages/settings)
Then, after you have all of these, compare them carefully to the instructions and described settings in the manuals.
From there, if everything looks ok, contact Dynon (and provide the diagnostic file).

You say the Garmin was working fine, but no data coming to the Skyview. It's likely one of the following, in what I'd say is the order of likelihood:
You have a bad wire either between the Garmin and the Arinc box, or the Arinc box and the SV (or power to the Arinc box); could be a bad crimp, broken solder, pin not fully inserted, or some other cause of intermittent connection.
Bad configuration on one side or the other (they can be subtle...e.g., on the 430W at least, there's a difference between something like, IIRC, Aviation and Aviation+, or maybe it was GAMA and GAMA+, whatever...just check carefully)
Bad Arinc box; only Dynon would likely be able to sort this out, but if you have access to another box that you could swap out (from a friend?), that would help.

My money is configuration, but I wouldn't rule anything else out, especially connections.