Autopilot Servo

[Bob Cook]

The electronics portion can come out without taking the motor out if I remember correctly.
You should be able to get the unit number off the equip list (original).

There are two large transistors that is probably one is the culprit.
One controls one direction and the other, the other direction. I am sure one of these are blown.

If you have an electronics person you can check using a voltmeter in which a control voltage determines direction. You can check this at the plug. There is a p/n tag on the unit giving model, revision number of the unit. From this I can give you the correct pinouts and semi conductor part numbers. You should be able to ground test it by putting engaging autopilot and trying to assist the wheel while turning the roll command pot (console). If your assisting helps and the motor appears to be working then it may be the clutch that is not working properly.

Ground test first and listen for noises and report back. Also check trim servo and if this is normal you know the main computer power supply is working properly. The main computer had +/- pwr supply problems.

You need to eliminate the servo first as it is the simplest to test then work backwards.

It is not that difficult if you can isolate the problem. There are three major components and it is hard for a radio shop to trouble shoot the system out of the aircraft. Many times the problem is in the wiring and not in the electronics portion. In fact it can be dirty connectors at the servo causing the problem.

let me know how you make out.

Bob