REFLECTOR: S-tec servo was IVO Repair?

[John Dibble]

I just took a short flight and happy to report that the S-tec is tracking both the
gps and vor very well.
Sid, you may want to check if your A/P needs centering.  What you do is turn on the
A/P with the gps and radios off.  Then put the A/P in nav mode and see if the stick
moves (may take several seconds to notice any movement).  It should not move.  If
it does there is a centering adjustment you can adjust to stop the movement.  It
will take several minutes to get it in just the right spot.  Worked for me.

John

John Dibble wrote:

> It tracks the heading bug fine.  S-tec told me that the heading bug signal is
> stronger and that may be why it works with that and not the gps or radio.  They
> told me that the servo should  run at a minimum voltage of 1.5, so I connected
> a D cell battery to the motor terminals and it ran fine, so the servo is ok.
> There is also a centering adjustment on the A/P.  Turns out that needed
> adjustment.  Also whenever I turn on the A/P with the engine off, I hear the
> roll servo running.  I understand that should not be happening.  When I
> adjusted the centering adjustment, the servo got much quieter, so I'm hopeful
> it will work better.  I plan to fly later and see.
> When I bought my plane, my A/P would not track the gps either.  One time during
> a business trip, I had an avionics shop check it.  The next day they had it
> working with the gps.  I agree the heading bug is all you need (for VFR), but
> the gps will really spoil you.
>
> John
>
> sbjknox wrote:
>
> > ----- Original Message -----
> > From: "John Dibble" <aminetech at bluefrog.com>
> > To: "sbjknox" <sbjknox at earthlink.net>; "Velocity Aircraft Owners and
> > Builders list" <reflector at tvbf.org>
> > Sent: Friday, June 17, 2011 8:41 AM
> > Subject: Re: REFLECTOR: IVO Repair?
> >
> > [snip]
> >
> > >   My S-tec autopilot quit tracking gps and vor signals.
> > > I've been told to send in the servo, but I plan to do some checking on
> > > this as well.
> > >
> > > John
> > >
> > Does it track the heading gyro ok?  If so, it is not the servo.
> > My S-tec has never tracked the GPS or VOR... that's the way it was when I
> > bought the plane ten years ago but it tracks the gyro well and that's all I
> > really need.
> >
> > I just re-read that last sentence... thinking about how I navigate
> > cross-country, I actually prefer to set the heading by hand.  That way I
> > have an active thought process (such as it is) and a hand action to
> > determine my heading.  And changing the heading bug on the gyro is easier
> > than changing a GPS waypoint or tuning a VOR receiver.
> >
> > $0.02
> > Sid