MGL Avionics User Forum

I cannot get the my Odessey to communicate with the Servos .They are connected to Com ex.The Comex is flashing 2/sec as required .Checked There is power to the servos. Message is AP disconnected and no Rx. I think their something basic I'm. Missing. Anybody have a test procedure.?
David

Do you have internal autopilot selected in the auto pilot setup menu, if so are the trio servos selected as well?

Mike

Internal ap + flight director and Trio selected
David

Just quick thing to check, USB lead running form EFIS to Coms Ext.
In my situation, if this USB lead is not connecting properly, I get similar diagnostics to this.

Try unplug and re-plug the USB cable into the another EFIS USB port.
As well at some stage, I was told a USB power mod was done to bridge power across to one of the PCB in one of my Voyagers, it was done to boost the USB power to the Coms Ext and then signal to my Trio Gold servos.

This outline of USB mod may not be totally correct, but it will do until someone can shed better light on that mod for us.


Cheers
JimJab

Thanks Jim i will try that, interestingly Paul has also said there was a previous issue with the USB ports. It would be good if someone could enlighten us on the mod.
David 8

The USB host ports on the EFIS supplies 5V power to connected devices. In this case the extender.
A dedicated 5V regulator is used in the EFIS for this. The regulator is on the same PCB that holds the host connectors.
It gets supplied by 12V from your power input. This is routed on the actual backboard (which is a large PCB). A solder joint connects the 12V to the board holding the regulator. This joint is right between the two host connectors (easy to spot).
We found that if you press the USB connector in very hard it is possible to break this connection. In later versions this was replaced with a wired connection.
Should you have an older version - remaking the solder joint is simple - just reflow the existing solder (you can add a bit more if you like).

However, in your case your Extender is flashing its LED. That means it is getting power. So no point looking at this.

Are you sure your RS232 to Trio servo wiring is correct (both RX and TX wired correctly, you have a ground connected (possibly with a small value resistor like 100 ohms between to protect against ground faults) and finally - your servos have power and ground ?

Hi Rainier

I have a client with the Voyager 1 and Trio Gold servos. The autopilot works but it is very violent when making turns etc. The aircraft is an RV 8 which is does travel at 155kts. it only needs a very small amount of movement to make it turn or go up and down. The autopilot makes too bigger movements and throws the plane around. What can we do to fix this issue.
Sorry if it has been discussed before.

Reduce the servo magnitude for bank if the control is too much.
With the Trio servos watch out for clutch slipping and excessive gear play. The clutch can be adjusted (you need to remove the cover).

Normally in my experience with the Trio servos the bank was good but the pitch dicey on some aircraft - could not get the required accuracy out of the servo for very small corrections with the aircraft I was flying at the time - the MGL servo sorted that out. The main issue was a significant dead band - move the arm in one direction then when it has to move the other there is a lot of gear slack that has to be taken up before things start to happen. This would obviously be something that can vary between servos - there are quite a lot of gears in there.

Just to close off on the original post ,we found a wiring issue and the Servos are now serviceable. Thanks for your help.
David 8