Dear Europa community:
I am experiencing a strange electrical phenomenon:
After engine start (Rotax 912ULS) and showing up usually at first higher RP
M (run up or later, during cruise), my MGL V6 radio freezes. I first though
t it is a radio problem but on the ground, engine OFF it works great, and f
or extended period of time. Frozen means frequencies dialed will show on LC
D screen but pushing any buttons will not work and radio is incapacitated.
It remains in this state until engine is OFF. I am operating a handheld, sa
me frequency which does NOT show any distorted reception or TX problems whi
le VX is frozen. The V6 does not RX and TX when frozen.
I have a good set of headphones and hear no unfamiliar background noise eit
her. However, I discovered that on my GRT Glass, engine monitor graphic ana
lyzer, formerly drawing smooth curves for all 4 EGT and CHT sensor temps,al
l 4 parallel temp curves have now sharp steep triangular positive and negat
ive =93spikes=94, approximately every second or so, in irregular patterns +
/- and different amplitudes. At higher RPM the amplitudes increase, at idle
they are hardly visible. But, no clicking or noise in the headphones.
I have a straight forward EXP-2 Bus system which worked flawless from day #
1 until 65 hours FT.
What really got me confused, and the radio suspect questioned is that my el
ectric VSI is now freezing as well or freezing at alarming altitude data di
splay (23,000feet last time). Where is my oxygen mask?
I have talked to ROTAX Canada but they had no clue yet.
Just in case, I ordered a new rectifier unit and capacitor in the hope of r
emedying the problem this way. Parts have not arrived yet.
Any ideas what the issue can be or how to trouble shoot this?
Thanks,
Christoph Both
EUROPA C-GPEL
75+ hours, Waterville, Nova Scotia, Canada
From: Bud Yerly <budyerly@msn.com<mailto:budyerly@msn.com>>
Date: Saturday, January 18, 2014 at 8:47 PM
Subject: Re: Europa-List: Other items on the Silent-hektik web site
Graham and other Regulator Haters:
The Silent-hektik (SH) may be just the ticket guys.
The GR6 I am sure is fine, but for the bucks it is not a credit card buy an
d plug and play as is the SH. It is LAA approved though.
I have had two Regulator failures in 12AY. The first was a result of a sho
rted stator. Not the Regulators fault.
The second due to a nasty bad habit which weakened the fragile innards of t
he poor Ducati. Others were lost due to high current load.
Recently I had a hard week of learning as Gary Leinberger and I did some mo
ds to his electrical, adding a gear driven B&C Alternator to his airplane a
nd splitting the buss to reduce the load on his Ducati/Rotax alternator.
We immediately found trouble with the newly installed Ducati. It would ove
rvolt, then the OVP would kill the alternator field or Control voltage. Wh
ich is really ODD.
In Normal Troubleshooting:
Typically I look for a C wire problem with the Ducati. If the voltage outp
ut is out of tolerance at 3-4000 RPM I go down to Lockwood and use their te
st bench. You can do it on the aircraft also. Hook up a 15 amp load ( I u
se three H4 auto driving lights for about 150Watts hooked up to the alterna
tor stud and don't power up any avionics or other bus related items) and ch
eck the voltage output on regulator. I check the R and B+ volts against th
e C wire (Control) and jot the info down. I put a rag or towel around the
Ducati to check how hot the unit is getting (always fun around a whirling p
ropeller). Usually it is only slightly warm. If the two voltages are the
same, at about 13.5-13.8 and the lights are nice and bright. Good to go.
If you have your ammeter set up as a load meter and another as an charge me
ter, you can easily do the same using your power hungry panel and lights.
The objective is to have a steady draw on the alternator and to check the o
utput and control voltages which should be the same... At Lockwood I drink
coffee and watch.
High voltage output is not common and as has been reported in this thread a
s far back as 2006, if the C voltage is low, this can drive the output volt
age up, trying to get the battery voltage back to its 12.0. Our problem wa
s not that. The C volts to B+ was within 0.1 volts. Why the high voltage?
I found through Lockwood that the RV12 community was having a similar pro
blem in their electronic busses... It is bus related.
Basic Ducati understanding has been commented on before by smarter people t
han I:
The Ducati is a switching regulator using Thyristors, which are nothing mor
e than fast acting switches, along with diodes to output and control DC vol
tage. Remembering back to my younger days with point controlled regulators
, I knew that the entire system (battery, resistance and voltage output of
the dynamo all had to meet specs for the regulator to cycle its switching r
elay properly to control the battery voltage for charging. Since the Ducat
i converts AC current to DC via a set of diodes, (making a pulsed and a som
ewhat noisy signal), it then adjusts the voltage by simply cutting off the
power pulses shutting off the current (dumping it to ground) through the Th
yristors and are controlled by a clever set of transistors and resistors wh
ich feed the dump signal (or switch signal) to the Thyristors. As the volt
age drops, the Thyristors again switch off, and power is restored and the c
ycle continues in this on and off scenario. Thyristors pulse really fast (
100,000 times per minute) and don't wear out normally. However, they do
get abused by either drawing too much current than designed when locked in
the on position, trying to charge a poor battery, or the bus voltage is too
low being supplied back to the C terminal causing the Thyristors to again
stay open too long.
For proper performance, the battery voltage must be up to spec. There can
be no voltage drop between the C and R+. And the current draw on the bus c
annot exceed the rated output or the regulator, lest components get hot or
just burn out.
The light circuit is really a neat thing. It is C voltage run through a di
ode that goes to L spade then to the bulb (there is more to it than that bu
t simply put, it is slightly lower voltage than C). The other leg of the b
ulb goes to the C. With R/B+ and C equal, and only getting battery voltage
, the Light goes on because of the voltage difference between C and L. Ess
entially, as the alternator supplies power, the voltage of the L leg and C
leg become equal and the bulb extinguishes as it has equal power to each le
g. Of course it is important to note that if the transistor regulator circ
uit goes bad, you don't get voltage regulation or C control (unit shuts dow
n) and the light is inoperative. So the only real means of knowing if your
alternator has failed is an ammeter and a voltmeter in this failure mode.
This is common in all regulators.
Back to our problem:
I contacted a long time producer of electronic busses, Control Vision (Anyw
heremap) and talked to their lead engineer. It seems that our Ducatis do n
ot play well with a PTC controlled circuit. I don't know that much about P
TCs but essentially they are a PNPN type silicone transistor of sorts that
as voltage is applied, internal resistance in the PTC builds (causing heat)
and if too high of a current is applied, it hits its switching temp and th
e resistance in the PTC goes up exponentially. Effectively shutting off po
wer due to high resistance. Once power is removed from the PTC, it resets
itself. Kind of like a Thyristor, and like a switch. These items are affe
cted by bus voltage, panel temperature, power pulses and because they have
internal resistance can lower the C voltage causing the regulator to overvo
lt.
Since most of these automatic busses have over voltage protection (OVP) if
the regulator puts out too much voltage due to the control voltage drop, th
en the buss shuts down the C voltage to the regulator to stop the overvolta
ge condition. The Alt warning light comes on (no volts at the C terminal)
and the regulator is shut off.
The only way to reset the Alternator Control PTC is shut off the Master Swi
tch, killing power to the bus. NOT my favorite thing to do at night or wit
h an EFIS, as all goes tumbling into the night until we get power back. (T
hat=92s why its smart to have a battery back up.)
Our solution was to wire the Alternator and Battery leads from the firewall
studs to the EXP bus. Eliminating the OVP protection but safe as the Duca
ti/Rotax just can't produce over 15 volts. Then run a wire from the R+/B f
rom the stud to the alternator switch and then to the C. This allows for i
ndependent control of the regulator should it have to be shut down in fligh
t. Once the Volts from the fresh battery and the resistance of the PTC alt
ernator supply spade and OVP was removed from the control circuit, all is w
ell so far even with a 12.5 volt Odyssey battery in the system.
One other problem, which is my nasty habit, is after engine start, I immedi
ately engage the avionics bus switch (EFIS and Garmin 430s take a while to
boot). I was chastised by an automotive friend of mine. After engine star
t, the battery is of course down for a few seconds. At idle, the the Rotax
alternator is supplying very little power, and the regulator circuits go w
ide open delivering power to the battery for charging. Normally a good bat
tery in summertime takes 10-15 seconds to recover at 13.6 volts, but our li
ttle birds can barley meet 12 sometimes unless we spin up the RPM to 2500.
In winter, more time is necessary for the battery to recover. So the regu
lator stays in wide open mode trying to supply voltage it can't, and it pre
heats the regulator circuit. He commented that a little patience (somethin
g I do not have) by checking of the engine instruments after start and then
the status of charging on the Ammeter and volt meter would show me the bat
tery state before I slammed the bus on. So I am now going to spool up the
engine to 2500 and let it run there until the amps fall off and the volts s
tabilize, then turn on the avionics goodies. I tried the operation on Gary
's plane and sure enough, the battery took a good 10 seconds to recover fro
m start. Then I spun up the engine, smacked on the avionics (10 amps or so
) and the regulator took it all in stride. 12 AY also responded quite well
to the same procedure and cured my EFIS hang-up during start.
In a nutshell, Ducatis are a bit fragile. Keep the battery well charged (a
nd properly charged by the battery manufacture's recommendation), have a li
ttle patience and let the battery recover before turning on all the power h
ogs. Pay attention to the R/B+ to C voltage on panel install to avoid prob
lems.
If the Ducati is expected to produce 15 amps below 5000 RPM, you may in fac
t find that they only last a year or so. SH seems to know all this, but th
e translation is a bitch.
I hope to test one of these units and see how they hold up soon.
Odyssey battery owners should check out the www.odysseybattery.com<http://w
ww.odysseybattery.com> site for proper storage, charging (and chargers) and
recovery of these batteries. Trickle chargers are not the best for these
batteries.
Regards,
Bud Yerly
----- Original Message -----
From: GRAHAM SINGLETON<mailto:grahamsingleton@btinternet.com>
ister<mailto:paul.the.aviator@gmail.com>
Sent: Friday, January 17, 2014 6:11 PM
Subject: Re: Europa-List: Other items on the Silent-hektik web site
That looks very nice! Bout time too!
Graham
________________________________
From: houlihan <houlihan@blueyonder.co.uk<mailto:houlihan@blueyonder.co.uk>
>
Sent: Friday, 17 January 2014, 22:30
Subject: Europa-List: Other items on the Silent-hektik web site
Following on from the regulator item have a look at this on their web site
http://www.silent-hektik.com/UL_912_1.htm
My German is non existent so I may have got this all wrong.
Tim
httphttp://www.matronics.com/contribution===========
=
<http://forums.matronics.com/>
<http://forums.matronics.com/>
href="http://www.matronics.com/Navigator?Europa-List";>http://www.matronhr
ef="http://forums.matronics.com";>http://forums.matronics.com<http://forum
s.matronics.com/>
href="http://www.matronics.com/contribution";>http://www.matronics.com/c
|