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Advice needed on Trutrak Altrak and Digitrak

Geeman

Well Known Member
I purchase a used digitrak and a used altrak several months ago for my RV-6. The system was originally in a Defiant. I purchased a wiring harness from Stein and a hardware install kit from Trutrak. I looked at install pictures and installed similiar to many builders here. Roll servo mounted under pilot seat pan and altrak behind luggage bulkhead. No issues with overtravel.

Digitrak Problem

The torque is set to the highest setting and I have tried senstivities from high to low. I have a Garmin 696 wired in with baud rate set at 9600 on the 696 and 9600 on the digitrak. If the airplane wants to turn left due to uneven fuel burn (even a very small amount) the digitrak will loose heading, ie slow turn to left over time. The digital GPS track will come up when I engage the autopilot and it will try to hold heading, then the GPS track will go off and the heading hold symbol comes back on. After a few seconds in the left turn, the GPS heading will come back on the display and it will be 10-15 degrees from the initial heading. It will continue to do this and make big left turns. Does the same thing if the fuel loads want the airplane to turn right. I have discussed with Digitrak and they have given me several setting to try, but it always does the same thing. I am about to start my annual and was thinking of sending them the head unit and the servo so they can bench test it.

Altrak Problem
I have tried wiring the sensitivity to 12V, 0V, and ground. I get basicall the same results. If I am in choppy air the altrak does ok. If I am in smooth air when I engage, the plane will pitch down pretty hard and will then correct and pitch up hard and will never settle out. I sent the head unit to them and they said it checked out OK.

Since I will be down for my annual, I figure I would pull both units and both servos and send it to them. I have discussed my problems with Trutrak and they have been very helpful, but I wanted to see if someone on the VAF had any suggestions to try before I pull everything out.
 
Hi Kyle,

Your Digitrak issue sounds like a problem I had several years ago. It turned out to be one of the connector pins (or sockets, don't recall) was creating an intermittent signal. However, I seem to recall that if the system "degraded" from GPS steering to internal magnetometer steering it would not return to GPS unless you specifically told it to - in which case it would then try to hold the current GPS course.

Only other problem I had that caused gremlins like that was when I keyed the mic the pitch would react in an unsettling manner. That was ultimately fixed with an in-line filter - search the older posts for "filter" and "Trutrak," you should find that solution.
 
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