Skyview Trim position indication

Hello everyone,

Finishing wiring of my Skyview System on my RV-7 with:
2 Skyview Touch, AP module and VP-X, pitch and roll electric trim (Ray allen servos)

I'm connecting the Ray Allen servos to the Dynon EMS to have the auto-trim function.
Everything is connected, trim motors (pitch and roll) are working fine.
I have set up the Dynon and did the calibration to show trim positions.
The roll trim indication is fine, but the pitch trim indication doesn't work...
I initially did a temporary connection to check that things were working as expected and it did: trim running with trim buttons, and good trim position indication on the Skyview.
But after I finished the permanent connections the pitch indication isn't working anymore...
I re-checked all my connections and even re-did the wiring but I can't find anything wrong.
When I go in the Skyview Menu, EMS setup, sensor debug data I see that the values for pin 4 (pitch trim) don't change when I move the trim. The roll trim values are changing when I trim left or right.

I don"t know what to do next...

Any suggestions please.

Thanks,
Alain.

It is possible that the position data stopped coming out of the servo, but it is more likely that one of the wires is not connected, either position, power or ground for the position sensor. Those Ray Allen servos use 26AWG wire, so it is quite fragile. I would verify you have good voltage and ground back by the servo, then try to verify all of your connections at the servo.

Skyview

Alain,
Jesse is the man To answer this one! Me+skyview problem= trip to Saint Aviation. Jesse is like the Dynon Wisperer
Robert

Auto trim is a function of the Dynon AP knob panel and associated wiring. The trim position goes through the EMS and associated wiring.

As Jesse said, you likely have a wire loose somewhere but I wanted to be sure you are looking at the right wires

An open wire is one possibility. Another possibility is that two wires have been interchanged. The Ray Allen servo contains a POT (potentiometer) that senses trim position. The pot has 3 wires: 5 volts, ground, and signal. Measure the voltage on those 3 wires at the servo using aircraft ground a reference point. The signal wire should have a voltage somewhere between 5 and 0. And that voltage should change with trim position.
Another test is a resistance check of the pot with the 3 wires disconnected from the aircraft. Two wires will have unchanging resistance between them as the servo motor runs. The 3rd wire is the signal wire.

Good wires

Gents,
I have the two white wires connected directly to the Dynon AP module and the trims are moving correctly with the stick hat switch.
The three other wires are connected to the Dynon EMS.
I checked the blue (ground), orange (5V) wires and they are good at the servo.
For the blue wire (position) it has a constant 4.98 Volts! When I check that on the roll servo the blue wire voltage varies with trim position.
So I think maybe there is something wrong inside the pitch servo and the electronics that is sending the position to the EMS. But I want to confirm everything here bfore going further and maybe change the trim servo.
Thanks.

On the debug page, is the value stuck at 5V (or 4.999), 0V, or something else? This will tell us a lot.

You either have a bad sensor on the trim motor or you have swapped the +5V and the sense wire somewhere.

dynonsupport said:

On the debug page, is the value stuck at 5V (or 4.999), 0V, or something else? This will tell us a lot.

Click to expand...

Yes it's stuck at 4.98 Volts...

The Blue wire is ground, NOT position.
The Green wire is position (signal).
To verify the above and to check the operation of servo position, cut all 3 wires.
-
Connect an ohmmeter to the servo blue and orange wires. Operate the trim motor. The resistance should NOT change.
-
Connect the ohmmeter to the servo blue and green wires. Operate the trim motor. The resistance SHOULD change.
-
Connect the ohmmeter to the servo orange and green wires. Operate the trim motor. The resistance SHOULD change.

If the grounded wire going to servo pot is broken, then there will always be 5 volts on the signal wire.

Mich48041 said:

The Blue wire is ground, NOT position.
The Green wire is position (signal).
To verify the above and to check the operation of servo position, cut all 3 wires.
-
Connect an ohmmeter to the servo blue and orange wires. Operate the trim motor. The resistance should NOT change.
-
Connect the ohmmeter to the servo blue and green wires. Operate the trim motor. The resistance SHOULD change.
-
Connect the ohmmeter to the servo orange and green wires. Operate the trim motor. The resistance SHOULD change.

Click to expand...

That's correct: blue=ground, green=position, orange=5Volt
I made a small mistake in my message above...
It's all wired correctly and the voltage does not change, it stays at just under 5Volts.
I'll check what you say, but it's now late here and I'm leaving early tomorrow for a week away for work.
I will work again on the plane end of next week.
In the meantime I'll continue to check here ...

Thanks for the replies.

Alain

5V all the time indicates that either the signal wire to the SkyView EMS box is broken, or that the ground wire for the position sensor is broken.

Easy check. At the position sensor, use a voltmeter between the blue and green wires with SkyView powered on.

If you have 0V, your ground wire is broken
If you have <5V, then your signal wire is broken.
If you have 5V there, then electricity is broken...

Faulty potentiometer on servo?

I've redone my whole wiring.
Problem persists...

On the skyview sensor debug data page, and on my multimeter :
when the servo is in full down position it shows 4.99 Volts,
when the servo is in full up position it shows 0.13 volts
BUT it goes to 0.13 volts only when the servo is full up,
any other intermediate position shows 4.99 volts.

This leads me to believe that the potentiometer inside the servo is faulty.

Is my reasoning correct??

Alain.

Sounds like the pot is bad.