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Old 04-08-2017, 09:37 PM
AirHound AirHound is offline
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 99
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Originally Posted by RFSchaller View Post
I got about 400 hours out of my first VR, and I wonder if I overreacted to a low bus voltage after start. I'm not sure that ROTAX and Vans deserves the condemnation focused on them for the VRs.

I do carry spare spark plugs, VR and electric fuel pump when I am on the road since they are not readily available at Podunk Airport, USA!
Expecting the unexpected I see...

A mechanical pump?

What's the plan for a flat?
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Old 04-08-2017, 09:42 PM
AirHound AirHound is offline
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 99

Originally Posted by MMiller View Post
4/8/2017 update

This improvement may cause other issues...see post 78 below


Iíve been giving a lot of thought to your question about improving the regulator while itís opened up. We know these regulators fail from stresses in the power component leads. I always assumed these were operationally induced stresses. Iím beginning to rethink this theory. Yesterday I took apart a regulator (from the Sport Cruiser community) that was sent to me last week. This was a real eyeopener into the poor build quality by Ducati. Iím now wondering if these stresses were loaded on the components during manufacturing. With the new pliable gel potting compound the Operational vibrations induced on these pre-stressed leads may be enough to fracture the solder joints. This could explain why some last 10 hours and some hundreds of hours. Anyway, back to your question. There is a screw that holds down the bridge rectifier. My thought is to remove the screw, add an insulator and a washer to the screw and clamp both the PCB and the bridge. Then resolder the bridge and SCR leads to relieve any stresses. This will prevent any relative movement between these two parts.

As for that Sport Cruiser regulator

Thinking hi-adventure for those mounted in the cockpit which smoke and sputter to a short...
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Old 04-21-2017, 02:39 AM
omerward omerward is offline
Join Date: Jul 2005
Posts: 17
Default VR repair

Mike, I can't thank you enough for your thorough analysis of the VR failures. Mine had a burned G pin just like your photo. I opened it up and the solder connection from the pin to the PCB was cracked. I made a good solder connection on both G pins and it is working fine so far. Thanks again for your analysis.
Sam Ward/Conroe, TX KCXO/RV-12 Flying
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Old 04-21-2017, 08:00 PM
MMiller MMiller is offline
Join Date: Oct 2010
Location: Babylon NY
Posts: 50

Great job Sam, You're welcome and thanks for the feedback.
One suggestion, to increase the current carrying capacity of the G pins, donít use the black Rotax plug. Connect the fastons directly to the regulator. This will give you 100% mating contact.

Vanís, Rotax, Ducati, if you are listening...The Rotax 965-349 Ducati 362001 rectifier regulator is not a lost cause, but you need to deal with the design and manufacturing deficiencies if you want to put this behind you;

1) Eliminate the manufacturing induced lead stress on the power components.
2) The potting compound is too soft, and it's unstable over the rated operating temperature of the regulator. (95 Shore A to 30 Shore A)
3) Operating stresses (vibration) acting on the pre-stressed leads (item 1), in a potting compound that softens with temperature (item 2), over time results in PCB solder joint separation failures.
4) PCB connections that were never soldered indicate a poor (or nonexistent) inspection/QC process.
5) Insufficient clearance between an un-fused, high current carrying PCB trace and the rectifierís grounded metal case. The design relies on the insulating value of the PCB's solder mask layer.
6) Poor connector/plug/tab length design. The design of this 22 amp connection only allows about 80% of mating capacity between the connectorís male tab and female AMP fast-on.
7) The material for the male tab is 7.5mm thick, this equals .0295", the AMP faston is designed for an .032" tab thickness. The design falls 8% below optimum thickness.


Last edited by MMiller : Yesterday at 08:19 PM.
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