VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Avionics / Interiors / Fiberglass > Electrical Systems
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-25-2018, 06:09 PM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 185
Default Transient Short Indicator -- Dynon, EarthX, VP-X

Need some help from the brain trust.

First my setup.

I got a standard alternator (for IO360 M1B from Vans) an EarthX battery a VP-X pro and a Dynon (including there transponder) as well as a Garmin SL40 radio.

This setup has been working without any issues for close to 4 years now.

So about a week ago the Dynon gave me a warning that I had a short on my transponder which is mounted in the back of my RV-8 with the VP-X in the front.

Couldn't reproduce it on the ground no matter what I tried. As those things usually don't fix themselves I took the panels off and checked the connectors (took them apart) on both side as well as the wire. Couldn't find anything. (checked it twice ...).

So I put everything back together and did another testflight. Worked all fine on the ground but when I was up in the air the transponder indicated short on the VP-X again.

Now I couldn't even reset the short via a Dynon on the VP-X. Then I noticed one thing. If I switched the alternator off I could reset the transponder and it would not trip again.

When I switched the alternator back on not only the transponder showed a short, the radio which has a 100% diverse wiring path showed one too.

When I experimented a bit more I noticed that when the current from the alternator is low there are no issues but if it's high (like the first few minutes after you start the engine and it recharges the battery) there is an issue.

So at this point I am inclined to believe there is no real short and the problem is either with the alternator, the VP-X or the ErathX. Here the 3 theories:

1. VP-X is broken (I have a request in with VP-X support to see what they think).
2. The Alternator is somehow broken and causes the VP-X to be confused triggering there short protection.
3. The protection circuit on the EarthX is somehow broken causing the alternator to cause spikes which confuses the VP-X

Question is what to do next?

Thx

Oliver
__________________
Oliver Spatscheck
RV-8 & J-3
N-2EQ & NC-49762
http://www.spatscheck.com/oliver
Reply With Quote
  #2  
Old 08-25-2018, 06:21 PM
JosephineJ79 JosephineJ79 is offline
 
Join Date: Jul 2010
Location: OSH WI
Posts: 9
Default

Replace VP-X with fuses. They are light weight, inexpensive, and easy to replace without sending unit back to manufacturer.
Reply With Quote
  #3  
Old 08-26-2018, 10:21 AM
maus92 maus92 is offline
 
Join Date: Nov 2013
Location: Annapolis MD
Posts: 387
Default

Replacing the VP-X is not the solution.

I have a similar setup, except mine is a G3X. What CB value are you using for the transponder, what is the draw for the transponder, and is it the only device on the circuit? What gauge is the wiring to the transponder? How many power leads are there for the transponder? (Mine has two, but are fed from the same circuit atm.) Is there any correlation between the circuit tripping and the ack reply by the transponder? What is the ammeter telling you when the see the ack reply? Are you seeing any voltage spikes? What do the Dynon logs say? Have you checked the transponder antenna and cabling? I always check everything, even tangential stuff when I troubleshooting just to get a baseline.

Do you have a spare alternator you can swap in?


Good luck.
__________________
CA
2000 RV-8A | O-360, SDS CPI, FP, G3X Touch, VP-X, EarthX | Eastern Shore | KESN

Last edited by maus92 : 08-26-2018 at 10:31 AM.
Reply With Quote
  #4  
Old 08-26-2018, 01:40 PM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 185
Default

Quote:
Originally Posted by maus92 View Post

Replacing the VP-X is not the solution.

I have a similar setup, except mine is a G3X. What CB value are you using for the transponder, what is the draw for the transponder, and is it the only device on the circuit? What gauge is the wiring to the transponder? How many power leads are there for the transponder? (Mine has two, but are fed from the same circuit atm.) Is there any correlation between the circuit tripping and the ack reply by the transponder? What is the ammeter telling you when the see the ack reply? Are you seeing any voltage spikes? What do the Dynon logs say? Have you checked the transponder antenna and cabling? I always check everything, even tangential stuff when I troubleshooting just to get a baseline.

Do you have a spare alternator you can swap in?


Good luck.
Couple of answers. I am using:

a Dynon SV-XPNDR-261

http://www.dynonavionics.com/mode-s-transponders.php

with whatever setting Dynon configures it by default.

It's the only device on the circuit. Wire is 18G with a single lead. Breaker is set to 3A based on Dynon install guide it's on a 5A VP-X port.

I did check the trasnsponder cabling to the Dynon as well as the power leads (multiple times). Didn't check the antenna cable but it's about 1 foot long entirely visible and I didn't see any external damage. Will add that to my list.

Typical current << 0.5A . Don't recall what the spikes are during ACK replies and if that correlates. Something else to check.

Now one thing is that it worked flawless for 4 years. So something changed recently and I didn't change anything ... .

I don't have voltage spikes tripping the VP-X but that doesn't mean there aren't any... . They could be to short to trip the VP-X. I am wondering actually if that is what's going on but I don't have the correct instrument to measure those... .

Good tip with the Dynon logs. I didn't even think about those... . Wonder if the VP-X has any logs too.

I don't have a spare alternator will see if I can borrow one at the airport.

Thx

Oliver
p.s. and yes replacing the VP-X it is not an option... . There are so many benefits to this setup... . It's like saying to somebody who's fuel injector is acting up why don't you fly a glider ... . Never had engine problems while flying those ... .
__________________
Oliver Spatscheck
RV-8 & J-3
N-2EQ & NC-49762
http://www.spatscheck.com/oliver
Reply With Quote
  #5  
Old 08-26-2018, 09:05 PM
maus92 maus92 is offline
 
Join Date: Nov 2013
Location: Annapolis MD
Posts: 387
Default

Quote:
Originally Posted by spatsch View Post
Couple of answers. I am using:

a Dynon SV-XPNDR-261

http://www.dynonavionics.com/mode-s-transponders.php

with whatever setting Dynon configures it by default.

It's the only device on the circuit. Wire is 18G with a single lead. Breaker is set to 3A based on Dynon install guide it's on a 5A VP-X port.

I did check the trasnsponder cabling to the Dynon as well as the power leads (multiple times). Didn't check the antenna cable but it's about 1 foot long entirely visible and I didn't see any external damage. Will add that to my list.

Typical current << 0.5A . Don't recall what the spikes are during ACK replies and if that correlates. Something else to check.

Now one thing is that it worked flawless for 4 years. So something changed recently and I didn't change anything ... .

I don't have voltage spikes tripping the VP-X but that doesn't mean there aren't any... . They could be to short to trip the VP-X. I am wondering actually if that is what's going on but I don't have the correct instrument to measure those... .

Good tip with the Dynon logs. I didn't even think about those... . Wonder if the VP-X has any logs too.

I don't have a spare alternator will see if I can borrow one at the airport.

Thx

Oliver
p.s. and yes replacing the VP-X it is not an option... . There are so many benefits to this setup... . It's like saying to somebody who's fuel injector is acting up why don't you fly a glider ... . Never had engine problems while flying those ... .
You might want to check with Dynon to see if they have any history with their transponder and the VP-X. I know my EI vendor specifically said to "oversize" (over value) the VP-X ECB, even though the EI draws very little.
Apparently quick transients in the EI system could cause the VP-X to trip - not good for an ignition system, ahem. You *might* be able to uprate the circuit to 5A and test that out without damaging the 18AWG wiring.

I understand that this issue recently began after 4 years of trouble-free ops - that's why I suggested to swap the alt as an experiment since you noticed a difference with the alt on vs. off.

Good luck.
__________________
CA
2000 RV-8A | O-360, SDS CPI, FP, G3X Touch, VP-X, EarthX | Eastern Shore | KESN
Reply With Quote
  #6  
Old 08-27-2018, 05:59 AM
VNS VNS is offline
 
Join Date: Apr 2011
Location: New Zealand
Posts: 49
Default

No 2 - Voltage regulator triggering OV protection in the VPX. Swap out the VR/Alt assembly and test
__________________
Patrick ZK VNS
RV 9A
Reply With Quote
  #7  
Old 08-27-2018, 06:48 AM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 185
Default

Yes the alternator is on the top of my list too. So will try that and see what happens.

Just to be clear though it doesn't trigger the over voltage on the VP-X it triggers the short on the transponder circuit.

Oliver
__________________
Oliver Spatscheck
RV-8 & J-3
N-2EQ & NC-49762
http://www.spatscheck.com/oliver
Reply With Quote
  #8  
Old 08-27-2018, 08:49 AM
rv7charlie rv7charlie is online now
 
Join Date: May 2006
Location: Pocahontas MS
Posts: 3,154
Default

Transponders are 250 watt+ transmitters. 250W/14V=17.8 amps. Duration is very, very short, so you can get away with the recommended *circuit breaker*, which is typically very slow acting. The VPX's current detection time constant is unknown by anyone out here in the real world.

Just something to chew on....
Reply With Quote
  #9  
Old 08-27-2018, 11:38 AM
spatsch spatsch is offline
 
Join Date: Nov 2014
Location: Randolph, NJ
Posts: 185
Default

Quote:
Originally Posted by rv7charlie View Post
Transponders are 250 watt+ transmitters. 250W/14V=17.8 amps. Duration is very, very short, so you can get away with the recommended *circuit breaker*, which is typically very slow acting. The VPX's current detection time constant is unknown by anyone out here in the real world.

Just something to chew on....
Interesting. Time is 3ms.

I would totally go for this explanation if they system hadn't worked just fine for 4 years... . So why now ... .

Thx

Oliver
__________________
Oliver Spatscheck
RV-8 & J-3
N-2EQ & NC-49762
http://www.spatscheck.com/oliver
Reply With Quote
  #10  
Old 08-27-2018, 12:14 PM
Mich48041 Mich48041 is offline
 
Join Date: Apr 2008
Location: Riley TWP MI
Posts: 2,722
Default

If there is a high resistance connection, avionics with a switching power supply will draw more current to compensate.
__________________
Joe Gores
RV-12 Flying
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 11:40 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.