Autopilot Servo

[Bob Cook]

Gmas

there should not be any difference in semiconductors as they are all silicon. Secondly, the gain is not a real issue in this circuit.

PAUL
Get an ohmeter and check for shorts in Q7 and Q8 to start. If there is a short then replace. Lots of radio shops still have the original part numbers in stock including autopilot central.

Secondly
The potentiometer. We do not know if it is any good. put an ohmeter between pin K and H and then move the aileron. You should see the DC resistance change!
We are trying to determine the problem here and we are not eliminating anything.

There should be a reference 10 volts at pin C (when the electronics are plugged in. Can't measure voltages without these being back in place. It should be seen on top of r18.
CR1 is a zener diode.

If the pot does is bad then the same symptoms can occur.

so
1) check q 7,8
2) check pot R13 for continuity and value.
3) check CR1 / and check for 10 volts on CR1 adn top of r15.
4) you should see a voltage on pin K which is potentiometer output (all electronics back in place).
5) if no voltage in 4 then CR1 is shorted and i will give you the value.

Now lets go back and systmatically resolve these questions or get a technician and have him check these things out. Lets not guess and waste time.

I will scan the necessary diagrams or if you have a technician call me I will discuss the problem with him. Print out this email and give it to him as well..

We will get this fixed...................... somehow!

Bob