crkckr
Well-Known Member
This is a long post but please bear with me. Does anyone know, exactly, what is inside the Ducati ignition module used on a Rotax 447 engine? More specifically, I want to know how to kill one. The reason for this is that I have two that are dead, one of which was new and never even run but now appears to be as dead as the original!
I did take ohm readings on it when I first got it but it turns out my VOM was in the process of dying (miserable leaking alkaline batteries… I swear I’ll never use one again on anything important!). I didn’t realize it at the time, so the readings I got are not valid (nor did they match the readings that the CPS website says they should). I didn’t get a chance to check it until after I’d tried to start the airplane and got nothing, but the readings I get now, with a new meter, show opens where there should be none, and where there should be opens, there are low readings.
I’ve read that running the engine with one plug disconnected can cause problems (can a 447 even run on one cylinder? I’ve no idea.) and quickly overheat the module but that has certainly never happened in my case.
Here is what happened: When I first bought my airplane it started easily. Very quickly things went from easy to hard and then to impossible. I checked everything I could, traced all the wiring and decided to check the ignition switch. When I removed it, it came apart in my hands, so I assumed that was the source of the problem.
When I replaced the switch, I inadvertently soldered one of two ground wires (one ground to the engine, the other to the tach) to the ignition cutoff wire on the module and of course, was unable to start the engine. I finally traced the problem down and corrected the wiring. I can’t see how that could have caused any problems with the module, since it did nothing more than shut it down as it would normally be shut down, by grounding the yellow/black wire on the ignition module. This would explain not begin able to start the engine but not how the new module could get fried, as it apparently has. It's also possible that I had the tach ground wire soldered to the ignition cutoff wire, but as the cutoff wire checked ok with the meter, I don't think that is the case.
I read somewhere (I cannot remember where at the moment) that checking the module with an ohm meter can cause problems but I can’t see how that could be possible, since the meter is working with an output of no more than 3v and at most, 4000 mAh. But then, I have yet to take a module apart and don’t know what all is inside.
That’s on my list of things to do, is take one apart and find out what’s in it’s guts. I’ve seen videos’ and pictures of other types of modules and there seem to be a lot of transistors and such on a board, along with capacitors and probably diodes but I’d like to try and trace down exactly what it is that’s gone bad and perhaps fix it (ok, I admit, there’s not really much chance of that happening, but I’m going to give it a shot. It won’t cost me anything but time.)
So that’s where I am at the moment. I’m waiting on a used, but known good, module, which should be here any day now. I'll admit to being somewhat afraid to put it on the engine and try it, if there's something wrong with the engine I'm not aware of and might fry the new module as well. But until I get it, I really would like to know what’s possibly wrong with my engine that is causing these modules to die. If anyone has any ideas (other than gremlins… I’ve have found no signs of furry little critters eating away at my airplane!) as to why these modules are dying as they are, I’d sure like to hear it. I’ve considered the possibility that perhaps there’s something with the stator that’s off kilter but don’t have a clue what it could be. I do know my trigger is good and the gap is set correctly at .020” (although I’m told by people that should know that .018” is better) I’m currently at a complete loss and would welcome any ideas.
Thanks,
Mike
I did take ohm readings on it when I first got it but it turns out my VOM was in the process of dying (miserable leaking alkaline batteries… I swear I’ll never use one again on anything important!). I didn’t realize it at the time, so the readings I got are not valid (nor did they match the readings that the CPS website says they should). I didn’t get a chance to check it until after I’d tried to start the airplane and got nothing, but the readings I get now, with a new meter, show opens where there should be none, and where there should be opens, there are low readings.
I’ve read that running the engine with one plug disconnected can cause problems (can a 447 even run on one cylinder? I’ve no idea.) and quickly overheat the module but that has certainly never happened in my case.
Here is what happened: When I first bought my airplane it started easily. Very quickly things went from easy to hard and then to impossible. I checked everything I could, traced all the wiring and decided to check the ignition switch. When I removed it, it came apart in my hands, so I assumed that was the source of the problem.
When I replaced the switch, I inadvertently soldered one of two ground wires (one ground to the engine, the other to the tach) to the ignition cutoff wire on the module and of course, was unable to start the engine. I finally traced the problem down and corrected the wiring. I can’t see how that could have caused any problems with the module, since it did nothing more than shut it down as it would normally be shut down, by grounding the yellow/black wire on the ignition module. This would explain not begin able to start the engine but not how the new module could get fried, as it apparently has. It's also possible that I had the tach ground wire soldered to the ignition cutoff wire, but as the cutoff wire checked ok with the meter, I don't think that is the case.
I read somewhere (I cannot remember where at the moment) that checking the module with an ohm meter can cause problems but I can’t see how that could be possible, since the meter is working with an output of no more than 3v and at most, 4000 mAh. But then, I have yet to take a module apart and don’t know what all is inside.
That’s on my list of things to do, is take one apart and find out what’s in it’s guts. I’ve seen videos’ and pictures of other types of modules and there seem to be a lot of transistors and such on a board, along with capacitors and probably diodes but I’d like to try and trace down exactly what it is that’s gone bad and perhaps fix it (ok, I admit, there’s not really much chance of that happening, but I’m going to give it a shot. It won’t cost me anything but time.)
So that’s where I am at the moment. I’m waiting on a used, but known good, module, which should be here any day now. I'll admit to being somewhat afraid to put it on the engine and try it, if there's something wrong with the engine I'm not aware of and might fry the new module as well. But until I get it, I really would like to know what’s possibly wrong with my engine that is causing these modules to die. If anyone has any ideas (other than gremlins… I’ve have found no signs of furry little critters eating away at my airplane!) as to why these modules are dying as they are, I’d sure like to hear it. I’ve considered the possibility that perhaps there’s something with the stator that’s off kilter but don’t have a clue what it could be. I do know my trigger is good and the gap is set correctly at .020” (although I’m told by people that should know that .018” is better) I’m currently at a complete loss and would welcome any ideas.
Thanks,
Mike
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