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  • Re: 80 HP 912UL will not start

    by » 9 years ago


    Thanks for the response but I actually don't see it as ambitious at all but a rather simple project judging by the simplicity of the module itself. Could it be made more reliable, absolutely! That's already been determined. It's just sad that for a few pennies the module could be made far better and more reliable given the responses from the other electrical engineers that have inspected the unit and its components.

    I understand that this is not a Rotax built part but built "for" Rotax by Ducati. This module worked for your purposes and this is what you chose. And yes we are all aware of the service letter.

    What's really frustrating is that Rotax wants nearly $2000 from me to replace both of these modules. Given what we now know is inside and how easy they can be reverse engineered and duplicated for a mere fraction of that, do you think this is a fair price to us owners? Look at it this way, Rotax is asking for us to pay 11% of the costs of a brand new engine to replace the little ignition modules. Does that seem logical?

    If it's a known issue that these 2006-2007 model year modules go bad why does Rotax no offer up a program to swap these out? Is Rotax working on a "better mouse trap"? Seems like there are more and more people recently with this same issue.

    I'm not pointing blame at anyone specific but rather just venting at the cost of these modules when there is no way they should cost this much. I love my plane and the Rotax engine in it. It's the best engine out there for the LSA market in my opinion.

    Why did Rotax stop the program where they offered the advanced start module "kit" with the 2 modules and easy start built in? I've searched high and low and can't find this anywhere. I'd gladly pay $931.12 for this "kit" with 2 modules if I could find one.

    Can you offer me this same deal for the "kit" so I can repair my plane and enjoy flying again? These modules seem to be on backorder everywhere.

    Thank you

  • Re: 80 HP 912UL will not start

    by » 9 years ago


    You have done what i will do if i have the same problem , i will not pay $2000 for these modules that cost $400 the most.

    Thank you for the information.
    Chris

  • Re: 80 HP 912UL will not start

    by » 9 years ago


    Hi Shawn,

    I am more than happy to share all of the data that I have given that I am unlikely to do anything with it myself. I have a circuit diagram, parts list and even a PCB layout in Proteus (can supply Gerber files). I have sourced the connectors for the 4 pin and 6 pin variants.

    The following need to be considered if making one of these ignition modules:
    1. Can you construct it to a suitable IPC class?
    2. How are you going to test it?
    3. Are you going to improve it?
    4. How are you going to mitigate common mode failure?
    5. How are you going to indemnify yourself against any losses resulting form a unit failure?


    It sounds like some of us have the capability to fulfil the construction requirement so that is no problem.

    You cannot just put the module in the plane, start the engine and conclude that it works correctly. Without the original test specification you would have to determine suitable limits for the pick-up amplitude, supply voltage, load, etc. You may also want to do some temperature testing and some form of temperature cycling soak test.

    Some form of test fixture capable of driving the modules with different amplitude and frequency trigger signals whilst evaluating the performance of the output switch will be needed.

    Given that the current design has problems, are you going to try to identify where the weak points are and change them?

    If you build yourself 2 new modules then in some ways you have a potential common mode failure - you and your assumptions about how to build the modules ;-)

    The most difficult issue I see is how to defend yourself against potential claims following an accident where it is discovered that you have built the ignition modules yourself. I am guessing that in some countries you may be allowed to make your own components and your insurance will cover you. In other countries you would need approval from your governing body for the 'modification'. This could be more problematic.

    All of the above is possible, I do it for a living in a safety related industry but it is all non-trivial to do properly. I dare say that with appropriate evidence you could convince the various approval bodies to accept your module as a suitable replacement. The rub is that all this 'development' would have cost you a fair premium and if you included your time then it would likely cost you more than buying the Rotax units :-(

    Don't get me wrong, I love building and repairing things but you have to look at the whole problem. I think that the approach that the Dutch guys have taken at Carmo Electronics is interesting. They seem to have a test fixture where they can run the units and then determine what has failed, they then repair just that part of the circuit. That is probably more defendable than building an entirely new circuit.

    To proceed any further I think that you need to build a test fixture and that is not a 5 minute job. You need to be able to generate the trigger signals with the correct phasing and adjustable amplitude. This would allow you to investigate how a working unit operates as well as investigate a faulty unit. The circuit is simple, so once you can see what is not happening you can probably de-pot just the relevant section of the circuit and repair it.

    I am open to other suggestions and ideas...

    Kevin

    Thank you said by: RotaxOwner Admin

  • Re: 80 HP 912UL will not start

    by » 9 years ago


    Hi Shawn

    The original modules made by Ducati do fail regularly and I was looking at upgrading the components that fail. BUT the new modules like I have on my 912 are made by Motorini and they do not fail. I have searched the world looking for a dud Motorini unit and as yet have not found one single unit. The later version like mine has the softstart built in BUT you dont have to use it. The softstart option is only for the later 912 engines that have the updated timing on the flywheel sensors. If you do not enable the softstart option and this is just a matter of 2 wiring pins then the Motorini module is fine for use on the older 912 that do not have the modified timing. This is why I didnt go any further. I have all the circuits for the older one and was going to make one but why do that when it would be much better to make the later version that does both older and later motors and also is super reliable. So be on the lookout for the later Motorini modules and that is the one I want to pull apart

    Mark

  • Re: 80 HP 912UL will not start

    by » 9 years ago


    Thanks Kevin and Mark.....

    I am excited to pick up this project where you all left it. I have access to a perfectly good 2009 912ULS on a test stand. I can pull any and all measurements from this running engine with known good Ducati dual 6 pin modules. This is a good start, no pun intended.

    Mark, do the Motorini modules look different? Can you post a pic?

    Kevin, I have the files you posted but they are only PDF's of the board files. I use Eagle but a friend of mine uses Proteus and Altium. Are you willing to share files? My email is srmack68 at gmail dot com if so.

    I'm going to be taking several readings in the next week or so. This will be a great start as to what the little engine is doing.

    I am also going to send my defective units to Carmo for repair and then determine what they repaired or replaced.

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