"Tom Jackson" wrote in
news:Qexzb.408939$HS4.3307083@attbi_s01:

Sometimes, it holds for a while, then "lets go" and the plane starts a
very slow circle to the right. If I cycle the autopilot switch on/off
several times, sometimes it starts to hold again (sometimes it
doesn't.) It also seems that the more I use it, the more reliable it
gets.
Would any of these potentiometer adjustments help here (specifically
the one that has to do with gain/threshold?) Any other ideas?

"Let's go"? Does it actually drop off line, or just stop holding the
heading? If the former, it's probably a problem with the electromagnet
behind the switch. It can build up enough crud to keep the pull plate from
making good contact. Then the slightest vibration can sometimes cause it
to switch HDG mode off.

But I suspect that you mean that it just sometimes starts "going it's own
way." If so, and coupled with the "the more I use it the more reliable it
gets" comment, then I suspect you have an electrolytic that is shot (a very
common problem with these older units). That's going to need standard
electronic troubleshooting skills - i.e. figure out which one and replace
it.

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James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
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