Ray Allen Pitch Trim Wiring

[MJKTuck]

I have a Dynon HDX system. My standard pitch trim for the aircraft has been a simple panel mounted Ray Allen rocker switch connected to a tail mounted Ray Allen servo. It has worked well, the rocker switch is a momentary switch which moves the servo while the rocker switch is held in the appropriate direction for either up or down pitch trim. Release the switch and the servo stops.

I have recently added a SV-AP-PANEL and although I have yet to add Dynon autopilot servos, wanted to wire up the normal the pitch trim through the SV-AV-PANEL so that it will be ready for auto-trim one day. I followed the wiring diagram on page 18-7 of the installation guide. I did not provide power to the rocker switch (that will come from Pin 9), but I did join the black/white ground wire so that it provided ground to the rocker switch and Pin 2 of the SV-AP-Panel. The white wires coming from the switch went to Pins 3 and 4 and the the white wires from pins 7 & 8 went to the trim servo.

So the problem I have is that when I push the rocker switch, the trim servo operates but continues to run even when I release the rocker switch. The only way to make it stop is to dab the rocker switch in the opposite trim direction and it will stop. This is the same for either trim direction. Somehow, once power to the trim servo is initiated, Pin 9 continues to provide power (and ground presumably the ground from Pin 2 is by-passing the switch) until 'signaled' by a dab of opposite direction trim switch.

Maybe I have misunderstood the internal workings of the rocker switch - but I just cannot figure it out, probably because I need to see the internal wiring of the SV-AP-Panel to understand the current flow. Any help would be greatly appreciated.

 

[XPRSAV8R]

I know this isn't much help, but the desired configuration does work. I have my both pitch and roll trim wired to the SV-AP-PANEL and are auto-trimmed with the AP activated. I also have a hat-switch on my control stick that allows me to manually move the trim tabs, too. It's critical to be able to manually configure your trim settings after disabling the AP because the AP won't re-centre or return to default position, and I'm sure you may have different trim positions for landing.

I'll have to look for my wiring diagram, but don't give up.

 

[Sparky51]

I can't offer any help, but do have a question regarding the wiring of the trim servos through the SV-AP-Panel and stick grip hat switch. Does this need to go trough a relay deck or does the Skyview serve as the relay deck?

 

[Raymo]

I can't offer any help, but do have a question regarding the wiring of the trim servos through the SV-AP-Panel and stick grip hat switch. Does this need to go trough a relay deck or does the Skyview serve as the relay deck?

Once the SV-AP-Panel is installed, it provides relay functionality so the pre-existing relays would need to be removed from the circuit.

 

[MJKTuck]

Ok, so I figured out the problem. The wiring inside the Ray Allen rocker switch is quite different from what the kit plane manufacturer showed in it's wiring diagram. I took the rocker switch apart and disconnected the white/red wire and then rewired the ground wires from the '3' position to the '2' position. This way the micro-switches provided on/off ground when the switch was pressed. So basically converted the Ray Allen rocker switch wiring to match the Dynon wiring diagram. All works great now.

 

[Jaque]

I do not have the LED and trim rocker switch as I am wiring directly to the EMS for position and to the AP-PANEL for trim control. My question is that the manual has you wire in the EMS 5 volt supply to the trim motor for potentiometer power. I have the Ray Allen T2-7A and the wiring there notes only the 12-14 volt supply, no mention of a 5 volt position indicator supply. Can someone explain and or confirm the requirement for the 5 vplt supply here?

 

[Jaque]

Yes I understand but one of the 3 wires for the trim position is the 5 volt from pin 18 on the EMS. The trim motor and original LED position indicator that came with it have no reference to a 5 volt circuit, hence my question as to why it is required when the LED indicator is not used. Trying to get my head square on the circuit requirements.

 

[maartenversteeg]

The motor (two white wires on the ray alan) runs from 12 Volt. But the sensing potmeter is supplied form the 5 Volt so that the return sense line retunes a variable voltage between 0 and 5 Volt for the position indication.

 

[maartenversteeg]

So the 5 Volt supply for the potmeter is purely an Dynon EMS issue as this wants the returned position signal, that goes into the EMS be in the range from 0 to 5 volt

 

[Jaque]

That makes sense. Thanks, cob web in the brain is gone now!

 

[Jaque]

Off topic. Can the AP head be used to manually trim? The manual says the nose up, down feature is based on VS or IAS which I’m not clear on. I was hoping to have stick trim buttons in the pilot stick only and not the copilot stick.

 

[Raymo]

Off topic. Can the AP head be used to manually trim? The manual says the nose up, down feature is based on VS or IAS which I’m not clear on. I was hoping to have stick trim buttons in the pilot stick only and not the copilot stick.

When previously asked, Dynon said you cannot manually trim with the AP button panel. I have never tried, thanks to having trim on my Infinity grips.

 

[Jaque]

Thanks for all the info.
Just figuring out the stick grip wiring now. Looks like just the up, down wires and a ground. Any heads up on this?

 

[Raymo]

The stick ground outputs go to the AP panel. If you have roll trim, it will also go there. See figure 199 in the installation manual, rev AF.

 

[Jaque]

Just got a reply from Do. Doesn’t matter as long as the panel and stick share the same ground point. All my grounds go to a forest of tabs so should be good. Makes for an easier install as I have my 15 pin dsub complete.