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  #61  
Old 03-20-2017, 04:28 AM
salto salto is offline
 
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Location: Wee Waa Australia
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We had a lot of failures with the electrical system in our fleet of radial powered crop dusters due mainly to demands we put on the system driving the night lights during spraying ops.
We found a fix by hooking an 80 uf capacitor onto the alternator. Smoothed out the spikes and no more electrical failures. Simple fix and resolved a very frustrating problem.
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Last edited by salto : 03-20-2017 at 05:14 AM.
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  #62  
Old 03-20-2017, 04:53 AM
PCHunt PCHunt is offline
 
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Location: San Diego, CA
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Quote:
Originally Posted by salto View Post
We had a lot of failures with the electrical system in our fleet of radial powered crop dusters due mainly to demands we put on the system driving the night lights during spraying ops.
We found a fix by hooking an 80 mf capacitor onto the alternator. Smoothed out the spikes and no more electrical failures. Simple fix and resolved a very frustrating problem.
I would be very interested in the wiring diagram for that! What two terminals did you attach the capacitor to? Voltage rating? Part number?

Thanks in advance.....
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  #63  
Old 03-20-2017, 05:11 AM
salto salto is offline
 
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Going back a bit Pete and the electrical gurus can certainly correct me but I think it was as simple as a bridge between positive and negative on the alternator. We just secured the capacitor to the engine frame.
We've been all turbine since late 90's.
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  #64  
Old 03-20-2017, 03:45 PM
Hotscam Hotscam is offline
 
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You cannot connect a 80 uF capacitor across an AC generator.
Do it if you are keen on cowling explosions.
You can do this on an old DC unit, but these are not used for the last 10 years
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  #65  
Old 03-20-2017, 04:48 PM
salto salto is offline
 
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Can't find anything to support what you are saying Jack.
If that had been an issue I would know about it.
We were running alternators not generators.
Turbine aircraft run generators.
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  #66  
Old 03-20-2017, 04:59 PM
Mich48041 Mich48041 is offline
 
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This is the RV-12 forum. RV-12s have AC generators (dynamos). They do not put out DC. Most electrolytic capacitors are polarity sensitive. If they are connected backwards or to AC voltage, they may self destruct.
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  #67  
Old 03-22-2017, 11:34 AM
Hotscam Hotscam is offline
 
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An interesting test for non believers is to stick a capacitor in a 115 V socket.
It will explode like a fire cracker.

I think the capacitor is connected behind the rectifier across the DC voltage.
A lot of AC generators have a built-in rectifier so DC comes out.
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  #68  
Old 03-22-2017, 01:34 PM
rv7charlie rv7charlie is online now
 
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We're mixing apples & pomegranates.

I don't know of any field wound alternators (which *are* AC creators) that don't have the diode (rectifier) array built into the case of the alternator, so that the output on the B lead is DC (with ripple).

The only automotive/aircraft alternators I've ever heard of that actually output AC are the permanent magnet 'dynamos' that are likely the actual subject of discussion, since this is the -12 forum and I'm guessing they are on Rotax 9xx's. That design is always mated to a 'regulator' which is actually a combination of the diode block & regulator in one box.

So the poster who mentioned the capacitor could have made it more clear if he'd mentioned placing the cap on the output of the rectifier/regulator module. I'd bet he assumed it was understood where to place the cap.
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  #69  
Old 03-26-2017, 08:54 PM
MMiller MMiller is offline
 
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Location: Babylon NY
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Default How to repair a Rotax 965-349 / Ducati 362001 Rectifier Regulator.

How to repair a Rotax 965-349 / Ducati 362001 Rectifier Regulator.

This procedure only applies to regulators made after 2009, these are marked with the number 362001.

The failures are mechanical, caused by lead stress and fretting of the power component at the PCB. Usually they are easily repaired.

This work is not permitted on regulator that will be installed in an S-LSA, unless you get authorization from Vans.

To remove the potting compound;
- cut along case/potting compound edge with a utility knife. Do all four sides.
- pry between the case and the potting compound to separate it from the PCB.
- use an orange wood or ice cream stick to separate the compound from the PCB
- start from the corner shown in the picture
- the entire process takes 10 minuets
- the removed potting compound can be reused when you are done...if you were careful




Inspect and resolder these eight locations




The removed plug of potting compound can be reattached with high temp RTV.

The total cost $0.00...if you donít have buy the solder or RTV

Here is the link for a complete photo documentation of the repair to this regulator sample;

https://drive.google.com/open?id=0By...2FnUTRab2hYM0k

The test fixture is only required for troubleshooting, (and testing if desired.) This test fixture was built from built from material on hand, total cost $0.00.

Mike
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  #70  
Old 03-26-2017, 09:01 PM
DHeal DHeal is online now
 
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Location: Windsor, California
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As usual Mike, great stuff! Thank you. -- David
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