KFC-150 Self test

[rocketman]

After my recent annual on my 1982 201, the KFC-150 quit working. It seems like it had no power to it. So I went ahead and replaced the KC-192 (head) with another one that was operating when removed from another airplane. I even paid to have it bench tested before installation and everything was fine. After I installed it, the power came on fine but the seft test button on the KC-192, when depressed does absolutely nothing - the light stays lit and the unit does not go into the self test mode. After doing tons of research on this, I was pointed to the pitch servo and so I replaced that unit as well. The problem was still the same - the test light just stares at me like the unit is trying to tell me that it is too old for me to mess with. Well, I am not ready to give up on this just yet and to replaced it with a new digital Garmin unit. Any ideas of the problem? I don't think it can be in the servo's since the self test doesn't even begin checking the system. 

[alextstone]

I do not have any advice on troubleshooting but I do have several servos that I have for sale - cheap.  If you find you need another one, please let me know....

 

Alex 

601-470-7092

[Jake@BevanAviation]

Did you transfer the top and bottom board modules from your original unit to the new as removed unit?

[Fly Boomer]

5 minutes ago, Jake@BevanAviation said:

Did you transfer the top and bottom board modules from your original unit to the new as removed unit?

Would your advice be the same for a KAP-150?

[Jake@BevanAviation]

@Fly Boomer Yep, the flight computer needs to have the top and bottom modules installed to start a PFT test.  Checked this on the bench with a test KC191 (KAP-150). Without the modules the unit will not PFT.  Only the trim annunciation stays lit. 

[rocketman]

1 hour ago, Jake@BevanAviation said:

Did you transfer the top and bottom board modules from your original unit to the new as removed unit?

We verified that the two boards had the same modules including part numbers. So we kept the two boards the unit came with. Should I go ahead and replace these with the boards from my old unit?

 

[Jake@BevanAviation]

@rocketman if the top and bottom adapter modules match the specific modules needed for the aircraft in theory you should not need to swap.  However, it would be nice to know if when the unit was bench check was the aircraft modules installed or were the test modules used?  The only servo the system cares about for PFT functions is the trim servo.  Specifically, the regulated trim voltage and the feedback from the drive motor.

It might be worth it to swap the modules as you have no known history of the ones in the as removed unit.  If the modules in the as removed unit had broken pins it could explain why the unit will not PFT.  If the shop used the "test modules" there is a good chance the unit worked just fine.

[rocketman]

1 hour ago, Jake@BevanAviation said:

@rocketman if the top and bottom adapter modules match the specific modules needed for the aircraft in theory you should not need to swap.  However, it would be nice to know if when the unit was bench check was the aircraft modules installed or were the test modules used?  The only servo the system cares about for PFT functions is the trim servo.  Specifically, the regulated trim voltage and the feedback from the drive motor.

It might be worth it to swap the modules as you have no known history of the ones in the as removed unit.  If the modules in the as removed unit had broken pins it could explain why the unit will not PFT.  If the shop used the "test modules" there is a good chance the unit worked just fine.

Thanks - I am going to try that.