Saturday, 6 December 2014

Tiller pilot lives again

The trusty (untrustworthy more like)  tiller pilot had stopped working during our trip to Devon in the summer. After an initial glance over it I decided that I didn't have the time or inclination to sort it there and then so it got thrown in the Forepeak and forgotten about... I'm thinking of renaming the Forepeak as 'The Oubliette'
Anyway after a chat with Sparrow Steve yesterday the sorry thing came back to my shed of a head. so this morning I dug it out and set about either fixing it or binning it.
My initial thoughts where that it had blown a power transistor, apparently a coming fault on these. That was also wishful thinking as I already had some spare transistors after getting some for a friends Tiller pilot.  I did quick check with the multi-meter confirmed the ones on the PCB were ok.  I delved further and took apart the gearbox.  Success, I could instantly see that the drive had wound the rod back so far that it had jammed solid and the motor could not push it out.  I freed the screw thread and reassembled the gearbox.  Before restringing and reassembling the unit I decided to power it up with the Bench Supply, Damn, It wouldn't drive.  I took it apart again, the motor would spin up and change direction with changes from the flux gate, the compass control on the unit, but the slightest touch from my finger would stop it.  
I was scratching my head now and the only option was to request help on the PBO Forum.  So that done I put the kettle on and went back for another gander... 'You plank' is all I could think,  The display on the Bench PSU was showing minimal Amps while trying to operate the motor.  I'd set it up to test the on board components, as I increased the power from the psu the rod started to drive.  I've never been so glad to have been so dumb.
Restrung and reassembled it looks to be working fine again.  Going to be a while before I get a chance to test it in anger.