AP 74 Connection Lost

[Glastar41]

Hi
Hope you can shed some light on my A/P I have a D100 and
D120 with an AP74 and two servos, configured the DSAB
It found all 5 dynon components,I did the servo test and it worked fine, set up the servos all ready then when I press the
Trim elivator all the lights on the AP74 come on and stay on
Then a warning says AP74 connection lost and err err comes
Up in the bottom left corner of the screen then in turn the warning says pitch servo connection lost and roll servo connection lost. So I checked to see what software version
The D120 and D100 had in and the EFIS is version 5.4 but the
EMS has 5.4.3 don't know if this is a problem.or is it interference from the trim motor wires????
Hope you can help
Kurt

 

[Dynon]

The versions not being the same isn't how things should be, but that's not going to be the cause of your issue. Yes, you likely have some energy from the power going to the trim wires that's affecting your DSAB wires. Are your DSAB wires all twisted pair to minimize external interference? Are there any runs of DSAB that are in close proximity to the the current-carrying wires that go to the trim motors?

 

[Glastar41]

Thank you for coming back to me, all the DSAB wires are twisted but the trim wires do run in the same loom as the DSAB wires?? Should I separate them, and how far away
Do they need to be and is there any thing I can do such as
A ferrite on the trim wires??
Cheers
Kurt

 

[Dynon]

Yes, separate them. It's hard to say exactly the distance you'll need, but I suspect a few inches would really help. You'll need to experiment a bit.

 

[Glastar41]

Hi dynon
Spent the day at the airfield today to try and sort this auto pilot out but no joy I separated the trim wires and re routed
Them away from the DSAB wires but the problem is still there
Also I noticed today when I switch on the auto pilot the EMS
Disconnects from the EFIS only for a couple of seconds then re connects? Don't know if this is anything to do with the software
Being different, thinking about fitting some kind of suppression
To help with the spike coming from the trim motor???
Do you think it's worth trying or could it be somthing else?
Sorry for all these questions Iam running out of ideas
Kurt

 

[Glastar41]

Hi
Just to let you know I have two relays in the trim wiring so only
One control stick can be operated at once wondered if this had any thing to do with the problem

Cheers. Kurt

 

[Dynon]

A few more questions: What kind of airplane is this in? Where are you in the world? And what is the full complement of Dynon components? You might try to see if the issue can be traced back to a particular Dynon component by removing them from the network. The easiest ones to remove/isolate (by unplugging them) will probably be the AP74, each autopilot servo, the HS34 (if equipped), and possibly the EMS while testing on the ground.

 

[Glastar41]

The airplane is a Glastar and iam in the UK, I have two servos
An ap74 and a d100 and d120 also a garmin 496 GPS
I will try un plugging each component and see if this helps
Thanks for your reply
Kurt

 

[Glastar41]

Hi
Went up to the airfield today and as you asked I tried disconnecting each auto pilot component one at a time but made no difference. So I had some MOV varistors (metal oxide varistors) and I put them across the relays for the trim and
A presto cured the problem so it must of been some sort of interference a back EMF or somthing, anyway going to put it all
Back together tomorrow and take her for a flight I will let you know how it goes
Thanks. Kurt