Hi David.
One thing to bear in mind is that there are, as I understand it, several
modes of failure of the Ducatti unit the most benign being that it just
stops charging the battery and feeding the services.
This is as you describe and as I also suffered ( why does this happen mid
channel?) but I believe it can fail and possibly allow high voltage DC or
AC onto the bus giving your expensive radio and other clever stuff a real
hard time !
In the UK there is very little difference in cost between the Schicke and
the Ducatti they are very similar in size and the wiring is only slightly
changed , one wire not connected, and the generator fail light has to
become an LED.
Tim
On 21 January 2014 19:13, David Joyce <davidjoyce@doctors.org.uk> wrote:
> davidjoyce@doctors.org.uk>
>
>
> Nigel, Fascinating and impressively erudite. You have totally convinced m
e
> that the way all new builders should go is with a Mofset bit of kit.
> However my personal solution is to take the odd Ducatti at sale price of
f
> anyone not planning to fit them and fly with a spare! In 1000hrs I have h
ad
> one failure. That was inconveniently 1/3 way between Holland and Clacton,
> but there was enough juice in the battery to get me all the way home with
a
> bit of thoughtful systems management. I currently fly with Rowland's
> spurned new Ducatti in my spares department under pax seat, but am prepar
ed
> to offer a modest price for another unwanted Ducatti!
> Regards, David
>
> "nigel_graham@m-tecque.co.uk" <nigel_graham@m-tecque.co.uk> wrote:
>
>>
>> I have followed this discussion with great interest and with an
>> increasing sense of D=E9j=E0 vu.
>> When the issue of regulator/rectifier failures occur withing the Rotax
>> community, the standard fix seems to be to simply replace like with like
>> (at elevated Rotax pricing) and fly on until the next unit fails.
>>
>> Up until about five years ago, nearly all modern Japanese motorcycles
>> used the same technology as that found on the Rotax 91x series engines,
>> permanent-magnet generators controlled by SCR rectifier/regulators. It
may
>> come as some surprise that for an industry renowned for precision and
>> reliability, nearly all of these major motorcycle manufactures have at s
ome
>> time, been plagued by problems with their SCR based rectifier/regulators
>> failing and burning out alternators and wiring, cooking batteries and in
>> extreme cases, squirting unregulated AC into the wiring loom and blowing
up
>> ECUs. It was just such a failure that "sparked" my interest :-(
>>
>> Known as "Shunt Regulators" the SCR technology runs extremely hot and
>> requires more cooling air than modern styling and space allows.
>> The solution was a move towards MOSFET controlled regulators and the
>> numerous web-based one-make discussion groups were full of information a
nd
>> advice on the reasons for failure, the benefits of the change and practi
cal
>> advice on how to convert.
>>
>> It was by trawling these groups that I was able to build up a good
>> understanding of how these R/Rs worked, what was causing the problem and
>> what the potential solution might be. I compiled what I considered to be
>> the best informed snippets of information into the attached document.
>> The first half gives an overview of a typical design of an SCR
>> Rectifier/Regulator for use on a permanent-magnet generating system and
the
>> second half discussed the relative merrits of SCR versus MOSFET.
>>
>> It would be interesting to know which technology the the after-market
>> Schicker and Silent-Hektic R/Rs use.
>>
>> Nigel
>>
>
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