S-Tec 30 issue

[xcrmckenna]

I have my electric trim working but now the altitude hold isn’t working on my auto pilot. The alt hold, trim up, and trim down lights are not lighting up on start up and my manual says they are suppose to. There is no action when I press the alt hold button on the yoke in flight. I was wondering if there is a fuse or something that could have that part of the autopilot shut down? But every other aspect of the ap is working. It follows the heading bug, track in GPSS and standard.

 

 

 

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[cbarry]

I had a similar issue several years ago and it turned out to be the pitch servo had gone out.  I had it repaired by Autopilots Central in Tulsa and they fixed that problem.  

[Cruiser]

Yes, there is a fuse mounted on the circuit board of the pitch computer module. 

This is a common problem and at some point I believe S-tec put out a service bulletin to increase the rating of this component. The fuse is soldered on the circuit board.