New reply from Spike Spencer
<p>Having been involved with certification of aircraft equipment required to operate in a Marine environment, I have difficulty in agreeing that HANSA servo equipment is "pretty reliable".</p>
<p>While it may be acceptable in their original automotive arena I don't understand the logic of using tin-plated connector pins in a Marine environment. Especially as loss of boat control is "Safety Critical" for our sailors. "The chaps in Australia" may make replacement easy; it would be better if that responsiveness were directed more at product improvement.</p>
<p>With reference to failure mode "3" in Paul's post above, as well as shorting the motor outputs when a relay is energised, it is also possible for a misguided volunteer to plug the battery "Y" lead into either of the motor drive cables. This takes both battery poles to ground across the relaxed relay contacts and the end result is the same – vaporisation of pcb tracks with that very distinctive electrical burning smell. A costly mistake !</p>
<p>While "KISS" is laudable, having to clean relay contacts is just no longer acceptable. It would only be a temporary solution and the problem (inrush current and switch-off arcing causing pitting) will soon bring those symptoms back. I'll post details of solid-state motor drivers in another thread soon.</p>
Original Post by paulbenn
Liberty Mk 2 controller wiring diagram (courtesy Barry Ring)
Attached is the wiring diagram for the Liberty Mk 2 controller, it’s reprinted by permission of Barry Ring, the system designer. Barry has given much advice in the past but in my experience the systems are pretty reliable with faults falling into 3 main groups.
1 – multiway connector between relay box and joystic box has intermittent connection. This can give a range of faults, power failure, failure of one servo or more. The chaps in Australia can supply pre-wired looms making replacement much easier, especially as they use an exotic pairing of Utilux pins and Molex bodies.
2 – Dirty or damaged relay contacts, often characterised by just one servo failing, sometimes just in one direction (i.e. the jib will only sheet in). This can be remedied by cleaning the contacts or replacing the relay if the damage is severe.
3 – Tracks on the pcb vaporised due to short circuit. There’s no fuse in the system so if you get a short on the servo side of things the track gets zapped by the high current. If you’re at this level you already know what to do…! If you don’t please feel free to contact me.